2D/2D phosphorene/BiOI S-scheme heterojunction for subminute photocatalytic water disinfection under real sunlight

Domain: chemistry
Published: 2026-02-02
Editorial outcome: major_revision

Abstract
Solardisinfection(SODIS),asapoint-of-use(POU)waterdisinfectionstrategy forcontrollingwaterbornemicroorganisms,servesmillionsofresidentsdaily inover50low-tomiddle-incomecountrieslackingbasicdrinkingwaterser- vices.However,SODISistimeconsuming(6-48hofsunlightexposure)dueto itsstrongdependenceonUVphotons,whichaccountforonly~4%ofthesolar energy.Thus,itisdesirabletocaptureadditionalenergyfromvisible-light photons(~50%ofthesolarenergy)toacceleratetheslowkinetics.Here,weuse phosphorenenanoflakes(PNs)andBiOInanosheets(BS)asmodelmaterialsto constructaheterojunctionphotocatalyst,illustratingthatsimultaneously modulatingtheinterfacialinteractionandbandalignmentbetweenthehet- erojunctioncomponentscanachieveadualoptimizationofthekineticand thermodynamicconstraintsinphoto-inducedchargecarriers,effectively enhancingtheutilizationofvisible-spectrumenergyformicrobialinactivation. Notably,asubminutephotocatalyticwaterdisinfectionperformanceis demonstratedbythePNs/BSheterojunction,completelyinactivating7logof E.coliwithin45sunderrealsunlight.Thisresultsinafirst-orderdisinfection rate~221timesgreaterthanthatofcommercialP25TiO .Thisworkprovides 2 insightsintothedesignofpotentantimicrobialphotocatalystsforPOUwater disinfectionapplications.

Introduction
Even today, over 800 million individuals, primarily living in low- to threat of waterborne pathogens,despite their limited effectiveness. middle-income countries, continue to endure the absence of basic Amongthese,solardisinfection(SODIS)iswidelyadopted,providing drinking water services, which typically include centralized water dailyservicestomillionsofpeopleinover50countries5.Thisisdueto treatmentanddistributionsystems1,2.Intheseregions,upto80%of its inherent simplicity and minimal infrastructure requirement, as it diseasescanbetracedtowaterbornemicroorganisms,withdiarrheal onlynecessitatesexposingmicrobe-contaminatedwaterintranspar- diseases alone accounting for over 480,000 deaths annually3,4. ent containers to sunlight, thereby enabling microbial inactivation. Unfortunately, this adverse situation shows a limited prospect of However,SODISgenerallydemonstratesarelativelylowdisinfection resolutionintheforeseeablelongduration,asthedeploymentofbasic efficacy,requiringatime-consumingexposureperiodof6–48hunder drinking water services is impeded by exorbitant capital expenses naturalsunlight5.ThisresultsfromtheheavydependenceofSODISon requiredandthelackofpre-existinginfrastructures(suchaselectrical UV photons, which constitute only ~4% of the solar energy and grids)intheseareas4.Consequently,fornow,theresidentsinthese experiencerapidattenuationastheypropagatethroughwater6. regions are compelled to rely on point-of-use (POU) disinfection To accelerate the slow kinetics, one approach is leveraging technologies at the household or community levels to mitigate the advanced forms of SODIS, such as photocatalysis, to capture additionalenergyfromvisible-lightphotons(~50%ofthesolarenergy) forwaterdisinfection7.Generally,aphotocatalystwithanappropriate bandgap can harness visible light to generate electron-hole pairs, which initiate redox reactions, leading to the formation of reactive oxygenspecies(ROS).Theoretically,theredoxpotentialsrelevantto ROSformationare−0.33V(O /(cid:129)O −)and0.28V(O /HO )forelectron- 2 2 2 2 2 drivenoxygenreduction,and1.90V(H O/(cid:129)OH)forhole-drivenwater 2 oxidation,allreferencedtoNHEatpH7(seerefs.7,8).TheseROScan subsequently disrupt the essential macromolecules of pathogens, affectingmultiplelevelssuchasmembraneintegrityandmetabolism, antioxidantenzymeactivity,andgeneticmaterial,therebyaccelerat- ing their photoinactivation8–10. To gain photocatalytic antimicrobial materials with strong visible-light-harvesting abilities, a universal strategyinvolvestheconstructionofheterojunctionsbyintegrating semiconductorcomponentswithcomplementarybandgaps11–17.How- ever,effectivelyutilizingabsorbedvisiblelightformicrobialinactiva- tion requires minimizing energy losses both during charge carrier transfer across the heterojunction interfaces and during the sub- sequent ROS generation by these carriers, a limitation that current heterojunctions remain unable to overcome. Specifically, for most existing heterojunctions: (i) the restricted interfacial interaction betweencomponentsleadstoaslowchargecarriertransferprocessat theinterfaceregions,causingenergylossfromakineticperspective; (ii)thelimitedredoxcapabilitiesofchargecarrierspreventthesuffi- cient generation of ROS, resulting in energy loss from a thermo- dynamic perspective. Consequently, the disinfection rates of heterojunctionsreportedtodateremainunsatisfactory,necessitating lightexposureoftenstohundredsofminutestoachievea5-to-7-log inactivationofbacteria3,18.

Inthisstudy,weusevisible-light-responsivephosphorenenano- flakes(PNs)andBiOInanosheets(BS)asillustrativematerialstoshow that optimizing the compatibility between the macroscopic geo- metricarchitectureandmicroscopicbandstructureofheterojunction components can effectively address both the kinetic and thermo- dynamic constraints of photo-induced charge carriers (see Supple- mentaryInformationforadditionalinformationonthepropertiesof thesetwocomponents).Ononehand,bothPNsandBSpossessa2D nanostructure,enablingthemtoformintimate“facetoface”contacts withrobustinterfacialinteractionsforfastchargecarriertransfer(2D/ 2Dheterojunctionsprovidelargerinterfacialcontactareasthanother counterparts,e.g.,0D/2Dor1D/2D)19.Ontheotherhand,awell-defined S-schemebandalignmentresultsintheaccumulationofelectronsand holes with enhanced redox abilities for elevated ROS generation. Benefiting from this dual-level optimization, the energy losses of visible-lightenergyareeffectivelysuppressedfrombothkineticand thermodynamicperspectives.Withanoptimalcontentof0.8wt%PNs, the resulting PNs/BS heterojunction exhibits a subminute photo- catalyticwaterdisinfectionability,achievingacompleteinactivationof 7log of E. coli within 45s under real-sunlight illumination. Further- more,integratingthephotocatalystintoacontinuous-flowfixed-bed reactor enables sustainable water purification for up to 24h, high- lightingitspotentialforpracticalPOUwaterdisinfectionapplications.

Results
Design,preparation,andcharacterizationofPNs/BS heterojunction

Amongthetwoillustrativeheterojunctioncomponentsselectedinthis study,specialfocusshouldbeplacedonthedesignandsynthesisof PNs.Asdistinctfrommostsemiconductormaterials(includingBiOI), phosphorenedemonstratesauniquelayer-dependentdirectbandgap accompanied by tunable redox capabilities of its charge carriers20. Thus, we initiate our study by employing density functional theory (DFT) calculations toinvestigate the bandgapenergy(E ) of PNs to g instruct the reasonable control over their layer thickness, thereby optimizingtheirperformanceasacomponentintheheterojunction. OurinvestigationrevealsthattheE valuesassociatedwithPNs,for g layersnumberingone,two,three,andfour,are1.70,1.48,0.93,and 0.66eV, respectively (Supplementary Fig. 1). This indicates that the controloverthelayernumberofPNsismorenecessarycomparedto BS.Giventhat,whileensuringthefullutilizationoftheentirevisible- light spectrum, a reduced number of layers in PNs can lead to enhancedredoxcapabilitiesofchargecarriers.Moreover,thesynth- esis of ultrathin PNs is expected to enhance their contact with BS, which is beneficial for strengthening the interfacial interaction betweenthetwocomponents.

Nevertheless,themostcommonlyusedliquidexfoliationmethod for PNs production frombulkblackphosphorus (BP) proves inade- quate in fulfilling this requirement, as multilayers are typically obtained (e.g., 5–8 phosphorene atomic layers using N-methyl-2- pyrrolidone(NMP),andeventhickerwithothersolvents)21–26.Thisis duetothesurfaceenergyofphosphorene(~58.6mJ/m2)ismismatched withthatofthewidelyemployedexfoliationsolvents,suchasNMP, acetone,ethanol,isopropanol(IPA),anddimethylformamide(DMF), hindering the enthalpy minimization of the mixed system27,28. How- ever, considering water’s significantly higher surface energy of ~102mJ/m2 and its miscibility with the aforementioned organic sol- vents, an organic-water mixture with an optimal surface energy for effectivePNsproductionisachievable.Thus,weinvestigatetheexfo- liationefficienciesof21distinctorganic-watermixturesforPNspro- duction employing the Lambert-Beer law as a fundamental analysis principle(SupplementaryFig.2).Asanticipated,weascertainadiverse range of mixtures exhibiting exceptional exfoliation performances, enabling the highly efficient generation of PNs. According to the experimentalresults,theoptimalsolventsareidentifiedasanethanol/ water system (V /V =50%) and a NMP/water system (V / ethanol water NMP V =80%).Giventhepotentialchallengeencounteredinremoving water NMPwithahighboilingpoint,theethanol/watersystemisselectedfor PNs production (see Supplementary Information for details of analysis).

Through the liquid exfoliation of bulk BP in the determined ethanol/water system, the outcome yields PNs characterized by a superior crystalline state, as validated by selected-area electron dif- fractionandRamanassessments(SupplementaryFig.3).Asdepicted inSupplementaryFig.4,theverticalextentdataextractedalongthe markedlinesrevealathicknessof~1.7–2.1nm,whichcorrespondsto 2–3atomiclayers,confirmingthesuccessfulproductionofultrathin PNs29.PNs/BSmaterialsarethenpreparedbyawetchemistrymethod, in which PNs are mixed with BS precursors (KI and Bi(NO) ·5H O), 3 2 enablingtheinsitugrowthofBSonPNs.Accordingtotheweightratios ofPNstoBS(xwt%),thesamplesaredenotedasxPNs/BS.Asshownin SupplementaryFig.5,theX-raydiffraction(XRD)patternof0.0PNs/BS clearlyindicatesitsalignmentwiththetetragonalphaseofBiOI(JCPDS No.10-0445).AcomparisonoftheXRDpatternsbetween0.0PNs/BS and0.8PNs/BSunderscoresthattheincorporationofPNshasaneg- ligibleimpactonthecrystallinestructureofBS.Moreover,itisnote- worthy that the XRD peaks associated with BP are conspicuously absentwithinthepatternof0.8PNs/BS.Thisabsenceisattributedto the fact that PNs are loaded at a relatively low concentration and exhibitaremarkabledegreeofdispersion.Thetransmissionelectron microscope(TEM)imageofPNsrevealsathin2Dflake-likestructure withwell-definededgesandsleekexternalsurfaces,whereastheTEM imageof0.0PNs/BSdisplaysa2Dsheet-likearchitecturemarkedby irregular edges and rough external surfaces (Fig. 1a, b). These 2D morphologicalfeaturesarefurthercorroboratedbyscanningelectron microscope(SEM)observations(SupplementaryFigs.6and 7).The high-resolution TEM (HRTEM) images of PNs and 0.0PNs/BS unveil their high crystalline quality (Supplementary Fig. 8). The image in Fig.1cillustratesaTEMviewof0.8PNs/BS,revealingthestackingofBS ontothesurfaceofultrathinPNs,establishinga“face-to-face”contact between the two 2D materials. The HRTEM image of 0.8PNs/BS demonstrateslatticefringesthatareconsistentwiththe(002)facetof BPandthe(110)facetofBiOI(Fig.1d)30,31.TheenergydispersiveX-ray spectroscopy(EDS)andX-rayphotoelectronspectroscopy(XPS)sur- veyresultsof0.8PNs/BSconcurwiththefindingsofTEMandHRTEM by confirming the elemental composition of Bi, O, I, and P in the material (Supplementary Fig. 9). The high-angle annular dark field- scanning transmission electron microscope (HAADF-STEM) image alongwiththecorrespondingelementalmappingimagesof0.8PNs/BS provideadditionalevidenceoftheconsistenthybridizationofPNsand BS in a uniform manner (Supplementary Fig. 10).Therefore, all the aforementionedresultsstronglyvalidatethesuccessfulpreparationof aheterojunctionofPNs/BS.

Stronginterfacialinteractionforimprovedchargecarrier transfer

The observed “face to face” contact between the two 2D compo- nents,PNsandBS,withintheconstructedheterojunction,isantici- patedtocreateastronginterfacialinteractionbetweenthelayers.To confirm this, synchrotron-based X-ray absorption near-edge struc- ture(XANES)analysisisemployed.TheBiL -edgeabsorptionedge 3 position of 0.8PNs/BS shows a negative shift compared to that of 0.0PNs/BS,suggestingtheoccurrenceofelectrontransferfromPNs to BS within the heterojunction (Fig. 2a). To further validate the electron transfer between the two materials, DFT calculations are performed. Figure 2b shows the differential charge density of the compositesystem,withblueandyellowregionsrepresentingcharge depletionandaccumulation,respectively.Theresultindicatesthat the surface of BS attracts electrons from neighboring PNs. Such electrontransferbehaviorisoftenassociatedwiththeestablishment ofanintimateelectronicinteractionbetweendistinctheterojunction moieties. To rationalize this observation, the work function (Φ) valuesofthetwocomponentsarecalculated,resultingin4.61eVfor phosphoreneand5.89eVforBiOI(Fig.2c,d).ThedisparityinΦ,in theory,canpromoteadirectionalelectrontransferbetweenPNsand BS,therebyestablishinganinternalelectricfieldthatinducesinter- layerelectroniccoupling.Moreimportantly,suchastronginterfacial electronicinteractionisexpectedtofacilitateafastchargetransfer processbetweenthetwomaterials.

Buildingonthisexpectation,femtosecondtransientabsorption spectroscopy is carried out. As illustrated inFig. 2e, f, excitation at 350nm induces distinct positive peaks for both 0.0PNs/BS and 0.8PNs/BSinthetimescaleof0.5–200ps,indicatingthedominanceof excited-state absorption during this interval. In contrast, the time range of 500ps–3ns ischaracterized by prominent negative peaks, demonstratingthatthegradualrelaxationofexcited-statepopulation backtogroundstateovertime.Interestingly,for0.8PNs/BS,inaddi- tiontoaground-statebleachingpeakat~526nm,astrongernegative featureisevidentonthelongerwavelengthside.Thiscanbeattributed to the stimulated emission resulting from the electron-hole recombinationbetweenPNsandBS.Figure2gillustratesthenormal- ized recovery kinetics of 0.0PNs/BS at 520nm (fitted using a two- exponential function), reflecting the interband diffusion and the trappingbyshallowtrapstatesofphoto-inducedelectrons.Theinte- gration of PNs with BSgives riseto anadditional ultrafastpathway (~2.1ps), which can be attributed to the transfer of photo-induced electronsbetweenthetwocomponents(Fig.2h).Thisultrafasttransfer processisanticipatedtomitigatetherecombinationofelectronsand holes occurring within each individual component, effectively pre- ventingphotonenergylossfromakineticperspective.

To validate this, the charge carrier separation efficiencies of 0.0PNs/BS and 0.8PNs/BS are systematically investigated using a range of characterization techniques. First, transient photo-current (TPC) response measurement is conducted. As depicted in Supple- mentary Fig. 12a, the TPC response of 0.8PNs/BS, which is sig- nificantly higher than that of 0.0PNs/BS, suggests an improved efficiency in the separation of electron-hole pairs upon the incor- poration of PNs with BS. Additionally, the results from electro- chemicalimpedancespectroscopy(EIS)measurementdemonstratea smallersemicircleradiusintheNyquistplotof0.8PNs/BScompared withthatof0.0PNs/BS,implyingareducedchargetransferresistance for 0.8PNs/BS, thereby promoting more efficient charge carrier separation(SupplementaryFig.12b).Furthermore,thesteady-state photoluminescence(PL)resultsofthesamplesrevealareducedPL intensityfor0.8PNs/BSincontrastto0.0PNs/BS,suggestingasup- pressedchargecarrierrecombinationin0.8PNs/BS(Supplementary Fig.12c).Moreover,thetransient-statePLresultsshowninSupple- mentary Fig. 12d exhibit an increase in average PL lifetime, from 19.8nsfor0.0PNs/BSto23.9nsfor0.8PNs/BS.Thisfurthersupports the higher electron-hole separation efficiency of 0.8PNs/BS, in agreementwiththeTPC,EIS,andsteady-statePLresults.Hence,all theabove-mentionedexperimentalfindingscollectivelyvalidatethat the energy loss during charge transfer process is effectively mitigated.

BoostedredoxcapacityforelevatedROSproduction

Theseparatedphoto-inducedchargecarrierscansubsequentlyparti- cipate in catalytic redox reactions for ROS generation. The redox capacitiesofthesechargecarriersaredeterminedbythebandalign- menttypeoftheheterojunction,which,inturn,governstheenergy efficiency of the ensuing ROS generation process.Considering this, band-structure characterizations are performed for the two hetero- junctioncomponents.First,theE ofBSisderivedfromtheplotof g (αhν)nversushνshowninSupplementaryFig.13a,whereαrepresents absorption coefficient, h stands for Planck constant, and ν denotes lightfrequency32.Inthisequation,nissetto1/2duetotheindirect bandgapnatureofBS.Consequently,thedeterminedE valueofBS g standsat1.68eV.Subsequenttothis,XPSvalence-bandspectroscopy analysisisconductedforBS.AsillustratedinSupplementaryFig.13b, thevalence-bandvalueofBSisobservedtobe1.36VversusNHE.This leadstothecalculationoftheconduction-bandvalueofBS,whichis foundtobe−0.32VversusNHE(SupplementaryTable1).Furthermore, theE ofPNsisascertainedthroughUV–visible(UV–vis)absorption g spectroscopyanalysis.AsshowninSupplementaryFig.13c,theiden- tifiedabsorptionedgeofPNsat731nmcorrespondstoanE valueof g 1.70eV. We then execute a Mott-Schottky test, revealing the n-type semiconductorcharacteristicofPNs(SupplementaryFig.13d).Thus, theflat-bandpotentialofPNs,extractedfromtheMott-Schottkyresult, canofferaroughestimationfortheconduction-bandvalue.Conse- quently,theconduction-bandvalueofPNsisestablishedat−0.44V versusNHE,andthevalence-bandvalueisthencalculatedtobe1.26V versusNHE(SupplementaryTable1).

Combining the band structures of PNs and BS with the above experimental and DFT findings on the electron transfer direction betweenthem,atypicalS-schemebandalignmentisexpectedatthe PNs/BSinterface(Fig.3a–c).Inthisbandalignment,PNs,characterized byamorenegativeconduction-bandposition,actasthereduction- typecomponent,whileBS,withamorepositivevalence-bandposition, function as the oxidation-type component. In the absence of light irradiation, electrons spontaneouslytransfer fromPNs to BS,estab- lishing an internal electric field across the heterojunction directed fromPNstoBS.Underlightirradiation,thisbuilt-infieldfacilitatesthe recombinationofphoto-excitedelectronsintheconductionbandof BS with photo-induced holes in the valence band of PNs. Conse- quently,energeticallyfavorablechargecarriersarepreservedinthe conductionbandofPNsandthevalencebandofBS.SuchanS-scheme bandalignmentisanticipatedtoaugmenttheROS-productionabilities of charge carriers, effectivelymitigating photon energy lossfroma thermodynamicperspective.

To confirm this,the visible-light-induced ROS generation ofthe samples is evaluated using specific reactions involving probe mole- cules. Specifically, nitroblue tetrazolium (NBT) can react with (cid:129)O−, 2 leading to a reduction in the absorption intensity at 259nm. As depicted in Fig. 3d, 0.8PNs/BS demonstrates the highest NBT con- sumptionamongthetestedsamples,correspondingtoa(cid:129)O−steady- 2 stateconcentrationof4.90×10−9Minitsreactionsystem,significantly surpassing the concentration observed in 0.0PNs/BS system (1.25×10−9M).Furthermore,furfurylalcohol(FFA),awidelyacknowl- edgedprobefor1O generation,ismonitoredforitsdecaytoquanti- 2 tativelyassessthe1O-generationactivitiesofthesamples(Fig.3e).The 2 1O steady-stateconcentrationin0.8PNs/BSsystemisdeterminedtobe 2 2.02 ×10−13M,exceedingthecorrespondingvaluein0.0PNs/BSsystem (1.38×10−13M). Moreover, p-chlorobenzoic acid (pCBA) is used as a reactiveagenttoevaluatethe(cid:129)OH-generationabilitiesofthematerials. As shown in Fig. 3f, 0.8PNs/BS exhibits the highest (cid:129)OH-production capacity, as evidenced by its more rapid pCBA decomposition com- paredtotheothertestedsamples.Thecorresponding(cid:129)OHsteady-state concentrationisdeterminedtobe5.20×10−14M,surpassingthevalue observedin0.0PNs/BSsystem(2.17×10−14M).Theresultsofelectron spin resonance (ESR) spectroscopy further support these findings, offeringadditionalevidenceoftheenhancedgenerationactivitiesof (cid:129)O−,1O,and(cid:129)OHover0.8PNs/BSrelativeto0.0PNs/BS(Supplemen- 2 2 taryFig.14).WethenexaminetheH O-productioncapacitiesofthe 2 2 samplesusingiodometricanalysis(Fig.3g).After60minofreaction, the accumulated HO concentrations in 0.0PNs/BS and 0.8PNs/BS 2 2 systemsarequantifiedtobe3.3and6.6μM,respectively,indicatingthe superior HO production activity of 0.8PNs/BS. Collectively, these 2 2- experimentalfindingsunequivocallyconfirmtheeffectivemitigationof energylossduringROSgenerationprocess.

Visible-lightphotocatalyticwaterdisinfectionperformance

An assessment of the photocatalytic disinfection activities of the samplesisthencarriedout.Gram-negativebacteriumE.coli,withan initial concentration of 7log, is used as a process indicator in all experimentsunlessotherwiseindicated.Visiblelightwithanoptical power density of ~100mW cm−2 isgeneratedusingasolarsimulator.As depictedinSupplementaryFig.15,PNsdemonstrateaminimalpho- tocatalyticdisinfectioneffectagainstE.coli,withbacterialconcentra- tion decreasing by less than 1log after 60min of illumination. Nonetheless, their incorporation markedly improves the photo- catalytic antibacterial performance of BS across varying loading amounts (Fig. 4a). Notably, 0.8PNs/BS shows the highest photo- catalyticwaterdisinfectionperformance,achievingacomplete7-log inactivation of E. coli (> 99.99999% disinfection efficiency) in only 5min of visible-light irradiation. In contrast, control experiments conducted under solely visible-light exposure or inthe presence of 0.8PNs/BS under a dark condition result in disinfection efficiencies below0.25logafter120min,demonstratingthatbacterialinactivation isattributedtovisible-lightphotocatalysis(0.8PNs/BScanharvestthe entire visible-light spectrum, as evidenced by UV–vis diffuse reflec- tance spectroscopy) (Supplementary Fig. 16). The contributions of variousROSduringthedisinfectionprocessofE.coliareinvestigated through a scavenger study. The experimental results illustrated in SupplementaryFig.17indicatetheparticipationoffourdistinctROS forbacterialinactivation,withcontributionsof(cid:129)O −>1O >H O >(cid:129)OH. 2 2 2 2 TheseROScontributetoE.coliinactivationbydisruptingcellmem- brane permeability, inhibiting energy metabolism, and damaging intracellularcomponents(SupplementaryFig.18).Themechanismof photocatalytic water disinfection by 0.8PNs/BS is shown in Supple- mentary Fig. 19. The broad-spectrum photocatalytic antibacterial activityof0.8PNs/BSisthendemonstratedbyitseffectivedisinfection of other waterborne bacteria, including E.faecalis,S.aureus,and P. aeruginosa(SupplementaryFig.20).Notably,theapproachproposed inthisstudy,whichstrategicallyoptimizesthecompatibilitybetween the macroscopic geometric architecture and microscopic band structureofheterojunctioncomponents,exhibitsbroadapplicability, asevidencedbythesignificantlyenhancedphotocatalyticantibacterial activitiesobservedupontheintegrationofPNswithBiOBrorBiOCl nanosheets(SupplementaryFigs.21and 22).

Thephotocatalyticantibacterialperformanceof0.8PNs/BS,witha 7-loginactivationofE.coliwithin5minundervisible-lightillumination, isconsideredoneofthemostremarkablebasedonathoroughreview oftheexistingliterature,particularlyintermsoftheextentofthelog reductioninbacterialconcentrationandtherapidityofdisinfection process(Fig.4bandSupplementaryTable2).Comparedwiththose thatachieveacompleteinactivationofE.coliwithin30min,suchas (Al O @v-MoS )/Cu,Cu-MoS ,andF-g-C N -30-EP,thebacterialcon- 2 3 2 2 3 4 centrationreductionachievedby0.8PNs/BSsurpassesthemby1-2log. Asfordisinfectionsystemscontaininganinitialbacterialconcentra- tionof7log,thereportedantimicrobialmaterialsthusfarnecessitatea minimumof60mintoachievethetotalinactivationofE.coli,whereas thesematerials,suchasSGO-ZnO-Ag,areaccompaniedbyacertain degree of biological intolerance. To the best of our knowledge, no previously reported photocatalysts have demonstrated such an extraordinarydisinfectionefficacywhenconfrontedwithaninitialE. coliconcentrationof7log.

Moreover, the photocatalytic water disinfection efficacy of 0.8PNs/BS is compared with that of the widely-studied P25 TiO 2 (20nm).AsshowninFig.4c,0.8PNs/BSoutperformsP25TiO under 2 real-sunlight irradiation (10:00 AM, local time, September 6, 2023, NortheastNormalUniversity,43.83°N,125.43°E),achievingacomplete inactivationof7logofE.coliinonly45s.Thiscorrespondstoafirst- orderdisinfectionrate(k)of9.30min−1(R2=0.97),whichexceedsthat ofP25TiO (k=0.042min−1,R2=0.95)byapproximately221-fold.More 2 importantly,0.8PNs/BSdemonstratesitsapplicabilityinacontinuous- flow fixed-bed reactor, enabling water purification for up to 24h, underscoringitspromiseforpracticalPOUwaterdisinfectionappli- cations(Fig.4d).

In conclusion, by utilizing PNs and BS as model materials, we demonstratethatoptimizingthecompatibilitybetweenthemacro- scopic geometric architecture and microscopic band structure of heterojunction components can effectively overcome both the kinetic and thermodynamic limitations of photo-induced charge carriers. Experimental findings, supported by DFT calculations, revealastronginterfacialinteractionbetweenthetwocomponents, enablinganultrafastelectrontransferprocess(~2.1ps).Furthermore, the established S-scheme band alignment promotes the efficient accumulation of electrons and holes with enhanced redox cap- abilities. Consequently, the energy from visible spectrum is effec- tively utilized for bacterial inactivation. Under real sunlight, the synthesized 0.8PNs/BS exhibits a subminute photocatalytic water disinfectionability,achievingacompleteinactivationof7-logE.coli within 45s. This delivers E. coli inactivation ~221 times faster than commercialP25TiO .Additionally,incorporating0.8PNs/BSintoa 2 continuous-flowfixed-bedreactorallowsforsustainablewaterpur- ification for up to 24h, underscoring its suitability for practical POUwaterdisinfection.

Methods
Chemicals
Iodine and tin were supplied by Guangfu Technology Development Co.,Ltd.(Tianjin,China).RedphosphoruswasobtainedfromHengx- ingChemicalReagentManufacturingCo.,Ltd.(Tianjin,China).KI,KBr, KCl,andpotassiumhydrogenphthalatewerepurchasedfromKermel Chemical Reagent Co., Ltd. (Tianjin, China). Bi(NO) ·5HO was pur- 3 2 chased from Aladdin Biochemical Technology Co., Ltd. (Shanghai, China).NMPwaspurchasedfromDamaoChemicalReagent(Tianjin, China). Ethanol, acetone, IPA, DMF, and FFA were purchased from FuyuFineChemicalCo.,Ltd.(Tianjin,China).NBT,pCBA,L-histidine, andP25TiO weresourcedfromRhawnTechnologyDevelopmentCo., 2 Ltd. (Shanghai, China). Ethylenediamine tetraacetic acid (EDTA) dis- odium salt was purchased from Beijing Chemical Works (Beijing, China). 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy (TEMPOL) was suppliedbyAcrosOrganics(NewJersey,USA).Allchemicalsemployed inthisstudywereofanalyticalgrade.

Synthesisofmaterials
SynthesisofbulkBP:AbulkBPcrystalwassynthesizedusingawell- establishedmethod12.Inastandardexperimentalsetup,commercial red phosphorus (2g) was dispersed in 15mL of H O and hydro- 2 thermallytreatedat200°Cfor12htoremovesurfaceoxidelayers,and thendriedinanoven9.Avacuum-sealedquartztubewasloadedwith 30mgofiodine,80mgoftin,and500mgofredphosphorus.This quartztubewassubsequentlypositionedwithinamufflefurnaceand subjected to a controlled temperature program. Specifically, the temperature was elevated to 600°C utilizing a controlled heating ramprateof3°C/min,andsubsequentlymaintainedatthistempera- turefor120min.Thesubsequentphaseinvolvedacontrolledcooling process,graduallyloweringthetemperatureto490°Cwithacooling rate of 0.4°C/min, and holding it at this temperature for 120min. Then, the temperature was progressively reduced to 120°C with a coolingrateof0.9°C/min.Finally,thequartztubewasallowedtocool naturallytoroomtemperature,culminatingintheformationofbulk BPcrystal.

Solventsurvey-informedPNssynthesis:Inastandardprocedure, 10mgofBPpowdersweredispersedin20mLofthecorresponding solvents,whichincludedNMP,acetone,ethanol,IPA,andDMF,aswell as their respective aqueous solutions. The resulting mixtures were subjectedtoanultrasonicexfoliationprocessforadurationof90min, utilizingawaterbath sonicator.Subsequently,thedispersions were subjectedtoacontrolledcentrifugationprocessat45×gforaduration of 30min. Following centrifugation, the supernatant samples con- tainingexfoliatedmaterialswerecollectedforfurtheranalysis,usinga UV–vis spectrophotometer (Hitachi U-2900). To ensure optimal accuracyandcomparability,theabsorbanceofthesampleswasmea- sured at 665nm, since all selected solvents demonstrated near- completetransparencyatthiswavelength.Basedontheexperimental results of solvent survey, an ethanol/water system (V / ethanol V =50%)wasselectedastheexfoliatingmediumforPNsproduc- water tion. PNs synthesis involved a sequential process of tip sonication followedbyice-bathsonicationofbulkBP.Initially,40mgofbulkBP was ground and subsequently introduced into the ethanol/water exfoliatingmedium(40mL).ThedispersionwasthensubjectedtoN 2 bubblingfor5min,followedbyatipsonicationtreatmentoperatingat anice-cooledenvironmentfor4h.Thesonicatorwasoperatedin1s on/2.5soffcycles.Subsequently,theobtaineddispersionunderwenta further ice-bath sonication for 2h (the purpose of ice bath is to maintainaconstanttemperature).Followingthis,thedispersionwas centrifugedat2862×gfor10mintoeliminateanynon-exfoliatedbulk BP,leadingtotheformationofPNsdispersion(0.128mgmL−1).

Synthesis of BS: In a standard procedure, both 35mL of KI (11.4mM) and 35mL of Bi(NO ) ·5HO (11.4mM) were prepared as 33 2 aqueoussolutionsandthenmixed.Theresultingmixturewasstirred for1hatroomtemperature.Followingthis,themixturewasheatedat 80°Cfor4hinaprogrammabletemperaturechamber.Theresulting materialswerecollectedthroughsuctionfiltrationandsubsequently driedinanovenat60°C,yieldingBS.

SynthesisofBiOBrandBiOClnanosheets:BiOBrnanosheetswere synthesizedusingamethodanalogoustothesynthesisofBS,except thatKIaqueoussolutionwasreplacedby35mLofKBr(11.4mM)aqu- eous solution. BiOCl nanosheets were synthesized using a method analogoustothesynthesisofBS,exceptthatKIaqueoussolutionwas replacedby35mLofKCl(11.4mM)aqueoussolution.

Synthesis of PNs/BS: In a standard procedure, 35mL of KI (11.4mM) aqueous solution was combined with varying amounts of PNsdispersion,whichwasthenblendedwith35mLofBi(NO ) ·5H O 33 2 (11.4mM)aqueoussolution.Theresultingmixturesunderwentstirring atroomtemperaturefor1h.Followingthis,themixturesweresub- jectedtoheatingat80°Cfor4hwithinaprogrammabletemperature chamber.Theresultantmaterialswerecollectedviasuctionfiltration andsubsequentlydriedat60°Cinanoven,resultingintheformation ofPNs/BSsamples.TheweightratiosofPNstoBSweresetat0.0,0.1, 0.5,0.8, and 1.0wt%,leading to the corresponding PNs/BS samples designated as 0.0PNs/BS, 0.1PNs/BS, 0.5PNs/BS, 0.8PNs/BS, and 1.0PNs/BS,respectively.

SynthesisofPNs/BiOBrandPNs/BiOCl:PNs/BiOBrsampleswith varyingPNsloadinglevelsweresynthesizedusingamethodanalogous to the synthesis of PNs/BS, with the sole exception of replacing KIaqueoussolutionby35mLofKBr(11.4mM)aqueoussolution.PNs/ BiOCl samples were synthesized using a method analogous to the synthesisofPNs/BS,withthesoleexceptionofreplacingKIaqueous solutionby35mLofKCl(11.4mM)aqueoussolution.

Characterizationofmaterials
Raman data were collected with a Horiba LabRAM HR Evolution spectrometer.Atomicforcemicroscope(AFM)imageswereacquired utilizingaBuskerDimensionICONinstrument.XRDdatawererecor- dedusingaBrukerD8Advancediffractometer.TEMandHAADF-STEM images were acquired using a JEOL 2100F instrument. SEM images wereobservedwithaHitachiSU8600instrument.XPSmeasurements wereperformedusingaThermoFisherScientificEscalab250Xispec- trometer.XANESanalysiswascarriedoutusingaSuperPhotonRing-8 GeVsynchrotronfacility.Femtosecondtransientabsorptionspectro- scopy measurements wereconducted with an UltrafastSystem LLC Heliospump-probesystem.Steady-stateandtransient-statePLspectra were recorded on an Edinburgh Instruments FSL980spectrophotometer.UV–visdiffusereflectancespectrawere recordedusingaShimadzuUV3600spectrometer.

Computationalmethod
DFTcalculationswereperformedusingaPWmatcode,withexchange- correlation interaction modeled through generalized gradient approximation(GGA)withPerdew–Burke–Ernzerhof(PBE)functional. Computationalparametersincludedanenergycutoffof70Rydanda Monkhorst-Packk-pointmeshof4×4×1.Geometryoptimizationwas conductedwithconvergencethresholdssetto1.0×10−5eVforenergy and0.01eV/Åforforce.Surfacemodelswereconstructedwitha30Å vacuumlayertopreventtheinteractionbetweenperiodicreplicas.To accountforVanderWaalsinteraction,theDFT-D2methodofGrimme wasemployed.Φwasdeterminedasthedifferencebetweenvacuum levelandE.
f

Electrochemicalandphotoelectrochemicalmeasurement
TPC,EIS,andMott-Schottkyanalyseswerecarriedoutemployingan electrochemicalworkstation(EC550,WuhanGaossUnionTechnology Co., Ltd.) in conjunction with a conventional three-electrode cell configuration.Inthisconfiguration,aPtplateservedascounterelec- trode, while a Ag/AgCl (saturated KCl) electrode was utilized as referenceelectrode.Theelectrolytesolutionusedwasa0.5MNa SO 2 4 aqueoussolution.Thepreparationofworkingelectrodeinvolvedthe followingsteps.Initially,anindium-tinoxide(ITO)glasswascleanedby ultrasonication using ethanol and IPA for 10min each, and subse- quentlydriedat60°Cinanoven.Then,1mgofmaterialwasdispersed in anethanol solution (V /V =50%),and 5μL of Nafion was ethanol water introduced.Thismixtureunderwentultrasonicationfor5mintoyield a homogeneous suspension. A 10μL aliquot of thissuspension was depositedontotheITOglasssubstrate.Afterward,theITOglasswas heated at 80°C for 30min to ensure optimal adhesion. Following coolingtoroomtemperature,theresultingproductwascatalyst-ITO working electrode. EIS and Mott-Schottky measurements were per- formed under dark conditions, while TPC measurements were con- ductedunderilluminationprovidedbya300WXelamp(PLS-SXE300, Beijing Perfect Light Technology Co., Ltd.). All measurements were carriedoutatroomtemperature.

ROSmeasurement
In a typical procedure, a material concentration of 1mg/mL was employed,withatotalreactionvolumeof30mL.A300WXelamp (PLS-SXE300,BeijingPerfectLightTechnologyCo.,Ltd.),coupledwith a400nmUV-blockingfilter,servedasthelightsource(opticalpower densityof~100mWcm−2). To determine the steady-state concentra- tionsof(cid:129)O −,1O ,and(cid:129)OH,weanalyzedthedecaykineticsofspecific 2 2 probemolecules9.NBTwasemployedtodetect(cid:129)O −,FFAwasusedas 2 anindicatorfor1O ,andpCBAactedasareactiveagentfor(cid:129)OH.The 2 rateconstantsforthereactionsbetween(cid:129)O −andNBT,1O andFFA,as 2 2 wellas(cid:129)OHandpCBAweredeterminedtobe5.9×104,1.2×108,and 5.2×109M−1s−1, respectively. Notably, to accurately ascertain the steady-state concentration of 1O , 1mM of IPA was introduced to 2 quench(cid:129)OH,takingintoaccountthesecond-orderreactionratecon- stantof1.5×1010M−1s−1between(cid:129)OHandFFA33.
ThequantificationofaccumulatedH O wasachievedthroughan 2 2 iodometric methodology34. Under an acidic condition, H O could 2 2 precipitate I− to form I −, yielding a distinctive absorption peak at 3 350nm.Atypicalexperimentalprocessinvolvedamixtureof1mLof KI solution (0.4M), 1mL of potassium hydrogen phthalate solution (0.1M),and3mLofreactionsolution.Thismixturewasshieldedfrom lightandallowedtoincubatefor30min.Subsequently,theresulting solution was analyzed using a Hitachi U-2900 UV–vis spectro- photometer,withafocusonmeasuringtheabsorbanceat350nm.All ROS measurement experiments were performed in triplicate to enhancethestatisticalrigorofthefindings.
ABruker A300spectrometer wascarried outforESRmeasure- ment.Toachievethis,10mgofphotocatalystwasuniformlydispersed inwaterormethanolthroughultrasonication.Subsequently,200µLof the resulting mixed solution wascombined with 100µL oftrapping agentsolutionandloadedintoacapillarytubeforESRtesting.Forthe ESRanalysesof(cid:129)O −and(cid:129)OH,5,5-dimethyl-1-pyrroline-N-oxide(DMPO) 2 wasemployedasatrappingagent.Meanwhile,theESRassessmentof 1O utilized2,2,6,6-tetramethylpiperidine(TEMP)asatrappingagent. 2 Notably, methanol-dispersed photocatalyst was used for (cid:129)O − ESR 2 testing, while water-dispersed photocatalyst was employed for (cid:129)OH and1O ESRevaluations.
2

Disinfectionperformance
E. coli K-12 was chosen as a process indicator to assess the photo- catalytic water disinfection activities of the synthesized materials. BacterialcellswereculturedinNutrientBrothat37°Cfor16htoreach a logarithmic growth phase. Subsequently, they were collected via centrifugationat2862×gfor10min,washedwithdeionized(DI)water, andre-suspendedinfreshDIwatertoachieveaconcentrationof~107 cfu/mL.Foralldisinfectionexperiments,amaterialdosageof1mg/mL wasapplied,alongwithabacterialsuspensionvolumeof30mL.Dis- infectionwasconductedusinga300WXelamp(PLS-SXE300,Beijing Perfect Light Technology Co., Ltd.) equipped with a 400nm UV- blocking filter. Its optical power density was maintained at ~100mWcm2,correspondingtothesolarirradianceintensityatthe Earth’s surface. A water cooling system was used to maintain the bacterial suspension at a constant temperature of ~25°C. At pre- determinedintervals,theE.coliconcentrationofthesuspensionwas assessed using the plate counting method. All bacterial inactivation experiments were performed in triplicate to enhance the statistical rigorofthefindings.

Scavengerstudy
Todeterminethecontributionsof(cid:129)O −,1O ,(cid:129)OH,andH O toE.coli 2 2 2 2 inactivation, four scavengers were used, including TEMPOL (2mM, targeting(cid:129)O −),L-histidine(0.5mM,targeting1O ),IPA(1mM,target- 2 2 ing(cid:129)OH),andFe-EDTA(0.5mM,targetingH O ).
2 2

Dataavailability
SourcedataareprovidedwiththispaperandareavailableinFigshare repository with the identifier https://doi.org/10.6084/m9.figshare. 3064586035.Alltherawdatarelevanttothestudyareavailablefrom thecorrespondingauthoruponrequest.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "The authors have attempted to optimize the compatibility between the macroscopic geometric and microscopic band structures of the heterojunction components to address the kinetic and thermodynamic limitations of photo-induced charge carriers. However, several critical issues remain unresolved. The resulting materials do not exhibit a well-ordered structure, and electron microscopy images fail to reveal any remarkable or novel features. Furthermore, the performance data presented do not demonstrate any significant improvement over previously reported results, raising concerns about the novelty and impact of the work. Given these limitations, I am unable to recommend this manuscript for publication in its current form. The work may be more suitable for submission to a more specialized journal rather than a broad scientific journal like Nature Communications.", "reviewer_2": "This manuscript reported the subminute water disinfection under real sunlight and the result is interest. Before it can be accepted, follow questions should be clarified.\n1. Based fig1, it is very difficult to know the thickness of BS and PNs, AFM results should be provided.\n2. In general, the interfacial building-in-field will be produced between BS/PNs. The author should provided the result about the interfacial building-in-field for BS/PNs samples.\n3. The ROS species are produced via photocatalysis of BS/PNs samples, this manuscript should provided the light absorbtion result and band level of BS/PNs samples,\n4. For P25 TiO2, it only has the activity under UV irradiation and BS/PNs samples has the visible activity, it is not appropriate to compare the performance under solar light irradiation.\n5. Because it is lack of many basic result on photocatalysis, active species, it is very difficult to judge this manuscript.", "reviewer_3": "Manuscript Number: NCOMMS-25-15152\nTitle: Dual Optimization of KineticandThermodynamic ConstraintsinPhoto-induced Charge CarriersforSubminute Water\nDisinfectionunderReal\nRecommendation: Reject\nGeneral Comments:\nThe authors of this paper studied Dual Optimization of KineticandThermodynamic ConstraintsinPhoto-induced Charge\nCarriersforSubminute Water DisinfectionunderReal.In addition, Summary tables of results should be added. Recycling\nperformance should be performed. Add new References.The content is not well categorized.\nDetailed comments\n1- Please write the name of the process ( photocatalytic activity) in the title.\n2- Write the name of the synthesized compound in the title of the article and Keywords.\n3- This sentence “ Additionally, the developed catalyst can be incorporated into a continuous-flow fixed-bed reactor,\nsustaining water purification for up to 24 h, demonstrating its potential for practical POU disinfection applications.” can be\ndeleted from ABSTRACT and written in the conclusion section.\n4- In ABSTRACT, you can write your analysis techniques ( XRD, EIS ,…)\n5- The words pathogens, with waterborne gastroenteritis are specialized biological words. Can you replace them with\nanother sentence?\n6- Write the relationship between POU and SODIS .\n7- In the introduction, you can write more specialized information about your work.\n8- Please write about bismuth-based compounds (properties, applications).\n9- Please write about the advantages and disadvantages of water disinfection.\n10- Explain the relationship between redox reactions and subsequently disrupt the essential macromolecules of pathogens.\n11- Draw the Graphical Abstract ( A graphical abstract is a single image that visually represents all the key aspects and\nmessages of your work) .\n12- This sentence (ii) the limited redox capabilities of charge carriers prevent the sufficient generation of ROS, resulting in\nenergy loss from a thermodynamic perspective \" is examined in terms of what thermodynamic point of view and\nthermodynamic parameters ?\n13- In the introduction, use the topic ( Nanomaterials are categorized into 0D, 1D, 2D and 3D based on their nanostructures)\nand write some content.\n14- What happens in the dark phase of the photocatalytic process?\n15- Please write about bismuth-based compounds (properties, applications).\n16- You have written this sentence: This gives a first-order disinfection rate ~221 times higher than that of commercial P25\nTiO2) several times. Please correct it.\n17- Provide a table of the history of published articles related to the topic of your work.\n18- Please write about phosphorene nanoflakes (PNs) (properties, applications).\n19- Why did you choose BiOI- BiOBr or BiOCl?\n20- Does the layered structure of bismuth compounds contribute to their photocatalitic activity?\n21- Explain more about the effects of compound morphology on the process.\n22- How many allotropes does phosphorus have?\n23- Write the properties of BP.\n24- Did you do part of the Synthesis of bulk BP (hydrothermally purified for 10 hours at 200°C to remove oxide layers)?\n25- Why did you choose the temperature of muffle furnace 600?\n26- Does calcination temperature and time have any effect on morphology?\n27- Why did you investigate the role of solvents? What is the most important point?\n28- What is the advantage of the method ultrasonic exfoliation process?\n29- What is the role of ice-bath sonication in synthesis?\n30- What solvent (Ethylene glycol or Ethanol, … )was used in the synthesis of BiOX ( X= I,Br,Cl)?\n31- Why was 35 mL of KI (11.4 mM) used? Why didn't you use the precursor BiCl3?\n32- Did you calculate the band gap energy of BS using the DFT method? Because of this sentence ( This indicates that the\ncontrol over the layer number of PNs is more necessary compared to BS.)\n33- Why do commonly used stripping solvents such as NMP, acetone, ethanol, isopropanol (IPA), and dimethylformamide\n(DMF) prevent minimizing the enthalpy of the mixed system? What parameters are influential?\n34- Introduce this parameter ( ΔH, Vmix, δ, φ, and Tbulk ).\n35- Increase the font of Raman spectra of bulk BP and PNs.\n36- Check again ) the Raman peak at 362 cm−1 is attributed to the out-of-plane vibration mode A1).\n37- Please write the JCPS standard card and Miller Index for (a) 0.0PNs/BS, (b) BP, and 0.8PNs/BS.\n38- Add the FESEM image of the compounds in the article. Explain Figure S4 more.\n39- What are the results of the thickness measurement? How did you draw this graph by AFM ? (Figure S4-b )\n40- How do you prove this (002) BP face and (110) BiOI face in the HRTEM image (Fig. 1d)?\n41- Please change XPS spectra, for example, examine the BS separately.\n42- What does the accumulation of lines in Figure 2. (e),(f) indicate?\n43- Does the number of layers have any effect on the results of (XANES) analysis?\n44- Is the wavelength of 520 nm ( Figure 2g( related to the excitation wavelength in PL Analysis? (electron-hole separation\nefficiency)\n45- Add a section with this title ( Photoelectrochemical measurements) to the article.\n46- What electrolyte was used in the Electrochemical impedance spectroscopy (EIS) analyses?\n47- What reference electrode was used in the Electrochemical impedance spectroscopy (EIS) analyses?\n48- Check all sources again.\n49- What is your reason for writing this sentence “Upon light illumination, this electric field can drive the photo-induced\nelectrons in the conduction band of BS to consume the photo-induced holes in the valence band of PNs”.\n50- Does p-type of PNs exist? Is BS type n or p? Please use Mott-Schottky for BS.\n51- It is suggested that you prepare all the energy of the bandgap that you have calculated using different methods in a table.\n52- Does the type of BS affect plan S-scheme ?\n53- In Figure 4. (a), the blue and yellow lines are the same, how do you explain?\n54- What is the reason for the number 45 s in Figure 4. (c)?\n55- What is the concept of absorption edge in the analysis of UV-vis DRS?\n56- Explain Electron spin resonance spectra further.\n57- Does PNs have an absorption edge in UV-vis diffuse reflectance spectroscopy?\n58- What is your reason for writing this sentence “ In this band alignment, PNs, characterized by a more negative\nconduction-band position, act as the reduction-type component, while BS, with a more positive valence-band position,\nfunction as the oxidation-type component”.\n59- Are synthesized samples reusable ( Recycling performance )? Please Perform XRD analysis even after recovery\n(reuse).\n60- Please include kinetic curve data( Ln (C/C0) = − kt ) for all analyses in the text.\n61- Do the degradation behaviour follow the first-order kinetics equation?"}, "author_response": "The authors are grateful for the editor’s and reviewers’dedicated efforts in improving\nthis paper. This manuscript has been revised to address all the issues raised by the\nreviewers. Reviewers’suggestions are in black italictype and our responses are indent\nand in normal font. The revised text as it appears in the manuscript is in blue.\nResponses to thecomments and suggestions are listed below.\nReviewer#1\nComments: The authors have attempted to optimize the compatibility between the\nmacroscopic geometric and microscopic band structures of the heterojunction\ncomponents to address the kinetic and thermodynamic limitations of photo-induced\ncharge carriers. However, several critical issues remain unresolved. The resulting\nmaterials do not exhibit a well-ordered structure, and electron microscopyimages failto reveal anyremarkableor novel features. Furthermore, the performance data\npresented do not demonstrate any significant improvement over previously reported\nresults, raising concerns about the noveltyandimpact ofthe work. Given these\nlimitations, I am unable to recommend this manuscript for publication in its current\nform. The work may be more suitable for submission to a more specialized journal\nrather thanabroadscientificjournallikeNatureCommunications.\nResponse: We sincerely thank the reviewer for the rigorous and thoughtful\ncomments. We fully understand your concerns regarding the structural order of the\nmaterial and its disinfection performance. After several months of careful\nconsideration and revision, we have provided detailed clarifications on these two\naspects below. If our efforts still fall short of your expectations, we would be deeply\ngrateful for more specific guidance, which would allow us to further improve and\nrefine themanuscript withyour valuable assistance.\n1. Regarding “The resulting materials do not exhibit a well-ordered structure, and\nelectron microscopyimages failto reveal anyremarkableor novel features”.\nResponse: In response to the reviewer’s comment on the absence of a\nwell-ordered structure in the TEM images, we provide the following clarification.\nIndeed, electron microscopy images of many heterojunction systems often reveal a\ncertain degree of ordering, particularly in 0D/2D or 0D/3D composite materials. This\nis largely attributable to the small size and distinct morphological feature of the 0D\ncomponents, which offer strong contrast and clear geometric distinction when\ndispersed on 2D or 3D substrates.As a result, such composites tend to exhibit visually\nrecognizable ordering. For example, the 0D/3D composite reported in Nature\nCommunications (2024, 15: 4807) clearly illustrates this phenomenon:\n[Figure Redacted]\nFigureR1.ElectronmicroscopyimagesofIn O /Nb O heterojunctionillustratingthedeposition\n2 3 2 5\nof0Dmaterialsontoa3Dsubstrate.\nHowever, the observation of well-defined ordering in 2D/2D heterostructures\nremains a well-known and intrinsicchallenge, not specific to our system. In our study,\nboth PNs and BS possess characteristic 2D features and exhibit comparable lateral\ndimensions. The inherently limited morphological contrast between the two\ncomponents makes it intrinsically difficult to resolve ordered interfaces at the\nnanoscale. More importantly, physical perturbations during material preparation\nfurther compromise structural ordering. For instance, the ultrasonic exfoliation\nprocess for PNs production inevitably leads to fragmentation and edge irregularities;\nand during the assembly of PNs and BS, random stacking orientations—such as\ndisplacement, twisting, and slight curling of nanosheets—are essentially unavoidable.\nThese factors collectively diminish the likelihood of obtaining a well-ordered\ncompositestructure.\nRecently, we have extensively surveyed the literature, including numerous\nrepresentative studies on 2D/2D heterojunctions. It is found that similar structural\nfeatures are widely reported across the field: even in seminal works, electron\nmicroscopy images typically show coexisting nanosheets without consistent stacking\norientations and rarely display pronounced long-range ordering. For example, the\n2D/2D composite reported in Journal of the American Chemical Society (2017, 139:\n13234-13242) illustrates nanosheets with irregular orientations and no apparent\nlong-range order:\n[Figure Redacted]\nFigureR2.TEMimageof2D/2Dg-C N /BP.\n3 4\nThe 2D/2D composite reported in Advanced Materials (2018, 30: 1800128)\nillustrates similar randomly oriented nanosheets:\n[Figure Redacted]\nFigureR3.TEMimageof2D/2Dg-C N /phosphorene.\n3 4\nHence, we believe our structural characterizations are consistent with what can\nreasonably beexpected from this class ofmaterials.\nNonetheless, this comment prompts us to further strengthen our experimental\nevidence. We have added SEM images to characterize the morphology of each\ncomponents individually, clearly demonstrating that both PNs and BS exhibit\nwell-defined 2D structures in their monomeric states, particularly with identifiable\nordering. While, as discussed above, the ordered nature of the final 2D/2D composite\ncannot be guaranteed, this does not detract from the key claim of our paper that “PNs\nand BS are compatible in terms of their macroscopic geometric structures”.\nAdditionally,TEM analysis of the composite reveals interfacial stacking between PNs\nand BS, and the elemental mappings indicate a high degree of spatial co-localization,\nfurther supporting the assertion of our paper that “PNs and BS form intimate\n“face-to-face” contacts”. We hope that this clarification and the newly included data\nadequately address thisconcern.\nFigureS6.SEMimagesofBP.\nFigureS7.SEMimagesof(a)BSand(b)0.8PNs/BS(theextremelylowPNsloadingof0.8wt%\nprecludestheirclearobservationintheSEMimage).\nFigure1.TEMimagesof(a)PNs,(b)BS,and(c)0.8PNs/BS.(d)HRTEMimageof0.8PNs/BS.\nFigure S10. (a) HAADF-STEM image and (b) the corresponding elemental mapping images of\n0.8PNs/BS.\n2. Regarding “Furthermore, the performance data presented do not demonstrate any\nsignificant improvement over previously reported results, raising concerns about the\nnoveltyandimpact ofthe work”.\nResponse: Thanks for your comment. In response, we would like to clarify that\nwe have comprehensively demonstrated the superior performance of the developed\nmaterial from two perspectives. First, we compare the 0.8PNs/BS material with some\nof the most efficient photocatalysts reported in the literature, which are carefully\nselected after extensive review rather than arbitrarily chosen. Since the disinfection\nefficiency in most of these studies is evaluated under visible light, we conduct\ncomparable tests under the same visible-light condition to ensure a fair comparison.\nPleasesee pages 17-18lines 331-344 in therevised manuscript as follows:\nThe antibacterial performance of 0.8PNs/BS, with a 7-log inactivation of E. coli\nwithin 5 min under visible-light illumination, is considered one of the most\nremarkable based on a thorough review of the existing literature, particularly in terms\nof the extent of the log reduction in bacterial concentration and the rapidity of\ndisinfection process (Figure 4b and Table S2). Compared with those that achieve a\ncomplete inactivation of E. coli within 30 min, such as (Al O @v-MoS )/Cu,\n2 3 2\nCu-MoS , and F-g-C N -30-EP, the bacterial concentration reduction achieved by\n2 3 4\n0.8PNs/BS surpasses others by 1-2 log. As for disinfection systems containing an\ninitial bacterial concentration of 7 log, the reported antimicrobial materials thus far\nnecessitate a minimum of 60 min to achieve the total inactivation of E. coli, whereas\nthese materials, such as SGO-ZnO-Ag, are accompanied by a certain degree of\nbiological intolerance. To the best of our knowledge, no previously reported\nphotocatalysts have demonstrated such an extraordinary disinfection efficacy when\nconfronted with an initialE. coli concentration of7log.\nIn addition, under real-sunlight illumination, the 0.8PNs/BS shows a first-order\ndisinfection rate that is 221 times higher than that of commercial P25 TiO , the most\n2\nextensively studied and benchmarked photocatalyst. Please see page 18 lines 345-351\ninthe revised manuscript as follows:\nMoreover, the disinfection efficacy of 0.8PNs/BS is compared with that of the\nwidely-studied P25 TiO (20 nm). As shown in Figure 4c, 0.8PNs/BS outperforms\nof7 log of E. coli in only 45 s.This corresponds to a first-order disinfection rate (k)of\n9.30 min−1 (R2 = 0.97), which exceeds that of P25 TiO by approximately 221-fold (k\n2\n=0.042,R2= 0.95).\nFigure 4. (a) Visible-light photocatalytic disinfection activities of PNs/BS materials. (b)\nVisible-light photocatalytic disinfection performance comparison of 0.8PNs/BS with the literature\nvaluesofotherphotocatalysts.TheplotgivestheloginactivationefficiencyofE.coliwithrespect\nto illumination time: (1) 0.8PNs/BS (this work), (2) (Al O @v-MoS )/Cu (ref. 33), (3)\n2 3 2\nSGO-ZnO-Ag (ref. 34), (4) Cu-MoS (ref. 7), (5) F-g-C N -30-EP (ref. 35), (6) CoFe O /HTCC\n2 3 4 2 4\n(ref. 8), (7) g-C N -TiO (ref. 13), (8) BiVO nanotube (ref. 36). (c) Disinfection performance\n3 4 2 4\ncomparison between 0.8PNs/BS and P25 TiO under real-sunlight illumination. (d) Visible-light\n2\nphotocatalyticdisinfectionactivityofacontinuous-flowfixed-bedreactorbasedon0.8PNs/BS.\nWe believe these results support the claim of significant improvement over\npreviously reported results.\nReviewer#2\nComments: This manuscript reported the subminute water disinfection under real\nsunlight and the result is interest. Before it can be accepted, follow questions should\nbeclarified.\nResponse:Thanks for thepositivecomment.\n1. Based fig1, it is very difficult to know the thickness of BS and PNs, AFM results\nshould beprovided.\nResponse: Thanks for the comment. As suggested, AFM results have been\nprovided, and the corresponding thickness values are presented. Please see page 7\nlines 130-133 intherevised manuscript as follows:\nAs depicted in Figure S4, the vertical extent data extracted along the marked line\nreveal a thickness of 1.7-2.1 nm, which corresponds to 2-3 atomic layers, confirming\nthesuccessful productionof ultrathinPNs [29].\nFigureS4.(a)AFMimageofPNswith(b)thecorrespondingthicknessmeasurementresults.\n2. In general, the interfacial building-in-field will be produced between BS/PNs. The\nauthor should provided the result about the interfacial building-in-field for BS/PNs\nsamples.\nResponse: Thanks for the comment. The presence of an interfacial\nbuilding-in-field for PNs/BS is confirmed through XANES analyses, differential\ncharge density calculations, and work function calculations. Please see pages 9-10\nlines 174-190in therevised manuscript as follows:\nTo confirm this, synchrotron-based X-ray absorption near-edge structure (XANES)\nanalysis is employed. The Bi L -edge absorption edge position of 0.8PNs/BS shows a\n3\nnegative shift compared to that of 0.0PNs/BS, suggesting the occurrence of electron\ntransfer from PNs to BS within the heterojunction (Figure 2a). To further validate the\nelectron transfer between the two materials, DFT calculations are performed. Figure\n2b shows the differential charge density of the composite system, with blue and\nyellow regions representing charge depletion and accumulation, respectively. The\nresult indicates that the surface of BS attracts electrons from neighboring PNs. Such\nelectron transfer behavior is often associated with the establishment of an intimate\nelectronic interaction between distinct heterojunction moieties. To rationalize this\nobservation, the work function (Φ) values of the two components are calculated,\nresulting in 4.61 eV for phosphorene and 5.89 eV for BiOI (Figure 2c and d). The\ndisparity in Φ, in theory, can promote a directional electron transfer between PNs and\nBS, thereby establishing an internal electric field that induces interlayer electronic\ncoupling.More importantly,such a strong interfacial electronic interaction is expected\ntofacilitatea fast charge transfer process between thetwomaterials.\nFigure2.(a)XANESBi-L edgesof0.0PNs/BSand0.8PNs/BS.(b)Side-viewdifferentialcharge\n3\ndensity map of PNs/BS, with yellow and blue regions representing the areas of net electron\naccumulation and depletion, respectively.Average potential profiles along Z-axis direction for (c)\nphosphorene and (d) BiOI. Transient absorption spectra of (e) 0.0PNs/BS and (f) 0.8PNs/BS\nrecorded at specified delay times. Corresponding kinetic decay curves of (g) 0.0PNs/BS and (h)\n0.8PNs/BS.\n3. The ROS species are produced via photocatalysis of BS/PNs samples, this\nmanuscript should provided the light absorbtion result and band level of BS/PNs\nsamples.\nResponse: Thanks for your suggestion. In response, UV-vis diffuse reflectance\nspectroscopy and band-structure data (including bandgap values and band edge\npositions) have been added to the revised manuscript. Please see pages 15-16 lines\n302-307in therevised manuscript as follows:\nIn contrast, control experiments conducted under solely visible-light exposure or in\nthe presence of 0.8PNs/BS under a dark condition result in disinfection efficiencies\nbelow 0.25 log after 120 min, demonstrating that bacterial inactivation is attributed to\nvisible-light photocatalysis (0.8PNs/BS can harvest the entire visible-light spectrum,\nas evidenced byUV-vis diffusereflectance spectroscopy) (FigureS16).\nFigure S16. (a) Dark and (b) light control experiments. (c) UV-vis diffuse reflectance\nspectroscopyresultsofthesamples.\nPleasesee pages 12-13 lines 237-252in therevised manuscript as follows:\nFirst, the E of BS is derived from the plot of (αhν)n versus hν shown in Figure S13a,\ng\nwhere α represents absorption coefficient, h stands for Planck constant, and ν denotes\nlight frequency [32]. In this equation, n is set to 1/2 due to the indirect bandgap nature\nof BS. Consequently, the determined E value of BS stands at 1.68 eV. Subsequent to\ng\nthis, XPS valence-band spectroscopy analysis is conducted for BS. As illustrated in\nFigure S13b, the valence-band value of BS is observed to be ~1.36 V versus NHE.\nThis leads to the calculation of the conduction-band value of BS, which is found to be\n−0.32 V versus NHE (Table S1). Furthermore, the E of PNs is ascertained through\ng\nUV-vis absorption spectroscopy analysis. As shown in Figure S13c, the identified\nabsorption edge of PNs at ~731 nm corresponds to an E value of 1.70 eV. We then\ng\nexecute a Mott-Schottky test, revealing the n-type semiconductor characteristic of\nPNs (Figure S13d). Thus, the flat-band potential of PNs, extracted from the\nMott-Schottky result, can offer a rough estimation for the conduction-band value.\nConsequently, the conduction-band value of PNs is established at −0.44 V versus\nNHE, and the valence-band value is then calculated to be 1.26 V versus NHE (Table\nS1).\nFigureS13.(a)(αhν)nversushνcurveand(b)XPSvalence-bandspectrumofBS.(c)UV-vis\nabsorbancespectrumand(d)Mott-SchottkyplotofPNs(theconduction-bandvalueofPNsis\n−1.05VversusAg/AgCl,correspondingto−0.44VversusNHE).\nTableS1.E valuesandbandedgepositionsoftheheterojunctioncomponents.\ng\nComponent E value(eV) Valenceband(V) Conductionband(V)\ng\nBS 1.68 1.36 −0.32\nPNs 1.70 1.26 −0.44\n4. For P25 TiO , it only has the activity under UV irradiation and BS/PNs samples\n2\nhas the visible activity, it is not appropriate to compare the performance under solar\nlightirradiation.\nResponse: We appreciate this comment, but we take a different position. P25\nTiO serves as a universally accepted benchmark photocatalyst. It is routinely\n2\nevaluated and applied under natural sunlight conditions in both academic research and\nindustrial practice. Thus, its inclusion provides a standardized reference that allows\nmeaningful comparison across different photocatalytic systems, regardless of spectral\nresponse ranges. Many influential studies in the field have adopted this comparative\nframework to contextualize the performance of novel photocatalytic materials (Nat.\nNanotechnol. 2016, 11, 1098-1104; Nat. Commun., 2019, 10, 2177). We hope the\nabove clarification addresses thisconcern.\n5. Because it is lack of many basic result on photocatalysis, active species, it is very\ndifficultto judgethismanuscript.\nResponse: Thanks for the comment. In response, we have conducted extensive\nqualitative and quantitative investigations on the ROS involved in our system.\nSpecifically, the generation of •O −, 1O , and •OH is confirmed by electron spin\n2 2\nresonance spectroscopy. Furthermore, the steady-state concentrations of these ROS\nare quantitatively determined through specific reactions involving probe molecules.\nThe accumulation of H O is also measured using iodometric analysis. These\n2 2\nquantitative measurements are not limited to the PNs/BS systems, we also evaluate\nthe steady-state or accumulated concentrations of ROS in PNs/BiOBr and PNs/BiOCl\nsystems. We hope these data can addresses this concern. Please see pages 14-15 lines\n267-291in therevised manuscript as follows:\nTo confirm this, the visible-light-induced ROS generation of the samples is evaluated\nusing specific reactions involving probe molecules. Specifically, nitroblue tetrazolium\n(NBT) can react with •O −, leading to a reduction in the absorption intensity at 259\n2\nnm.As depicted in Figure3b, 0.8PNs/BS demonstrates thehighest NBT consumption\namong the tested samples, corresponding to a •O −steady-state concentration of 4.90\n2\n× 10−9M in its reaction system, significantly surpassing the concentration observed in\n0.0PNs/BS system (1.25 × 10−9 M). Furthermore, furfuryl alcohol (FFA), a widely\nacknowledged probe for 1O generation, is monitored for its decay to quantitatively\n2\nassess the 1O -generation activities of the samples (Figure 3c). The 1O steady-state\n2 2\nconcentration in 0.8PNs/BS system is determined to be 2.02 × 10−13M, exceeding the\ncorresponding value in 0.0PNs/BS system (1.38 × 10−13 M). Moreover,\np-chlorobenzoic acid (pCBA) is used as a reactive agent to evaluate the\n•OH-generation abilities of the materials.As shown in Figure 3d, 0.8PNs/BS exhibits\nthe highest •OH-production capacity, as evidenced by its more rapid pCBA\ndecomposition compared to the other tested samples. The corresponding •OH\nsteady-state concentration is determined to be 5.20 × 10−14 M, surpassing the value\nobserved in 0.0PNs/BS system (2.17 × 10−14 M). The results of electron spin\nresonance spectroscopy further support these findings, offering additional evidence of\nthe enhanced generation activities of •O −, 1O , and •OH over 0.8PNs/BS relative to\n2 2\n0.0PNs/BS (Figure S14). We then examine the H O -production capacities of the\n2 2\nsamples using iodometric analysis (Figure 3e). After 60 min of reaction, the\naccumulated H O concentrations in 0.0PNs/BS and 0.8PNs/BS systems are\n2 2\nquantified to be 3.3 and 6.6 μM, respectively, indicating the superior H O production\n2 2-\nactivity of 0.8PNs/BS. Collectively, these experimental findings unequivocally\nconfirm theeffective mitigation of energy loss during ROSgeneration process.\nFigure 3. (a) Schematic illustration of the S-scheme band alignment at the PNs/BS interface.\nSteady-state concentrations of (b) •O −, (c) 1O , and(d) •OH, and accumulated concentrations of\n2 2\nH O overdifferentPNs/BSheterojunctions.\n2 2\nFigureS14.Electronspinresonancespectraof0.0PNs/BSand0.8PNs/BSwithvisible-light\nirradiationforthedetectionof(a)•O −,(b)1O ,and(c)•OH.\n2 2\nElectron spin resonance spectroscopy is widely regarded as a reliable approach for\nprobing ROS. To confirm the generation of •O −, 1O , and •OH over 0.8PNs/BS, two\n2 2\nspin-trapping agents, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and\n2,2,6,6-tetramethylpiperidine (TEMP) are employed. As shown in Figure S14, only\nweak signals corresponding to DMPO-•O − 2,2,6,6-tetramethylpiperidine-N-oxyl\n2\n(TEMPO), and DMPO-•OH adducts are detected for 0.0PNs/BS, suggesting that\nlimited ROS are formed. In contrast, 0.8PNs/BS exhibits significantly stronger\nresonance features, demonstrating a substantial increase in ROS generation. Moreover,\nno detectable signal is observed under dark conditions, confirming that ROS\nproduction originates exclusively from thephotocatalytic process.\nPleasesee pages 31-32in therevised Supporting Information as follows:\nFigure S20. (a) Visible-light photocatalytic disinfection activities of BiOBr and PNs/BiOBr\nheterojunctions toward E. coli. Steady-state concentrations of (b) •O −, (c) 1O , and(d) •OH for\n2 2\nBiOBrandPNs/BiOBrphotocatalyticsystems.(e)AccumulatedconcentrationsofH O forBiOBr\n2 2\nandPNs/BiOBrphotocatalyticsystems.\nFigure S21. (a) Visible-light photocatalytic disinfection activities of BiOCl and PNs/BiOCl\nheterojunctions toward E. coli. Steady-state concentrations of (b) •O −, (c) 1O , and(d) •OH for\n2 2\nBiOClandPNs/BiOClphotocatalyticsystems.(e)AccumulatedconcentrationsofH O forBiOCl\n2 2\nandPNs/BiOClphotocatalyticsystems.\nReviewer#3\nComments: The authors of this paper studied dual optimization of kinetic and\nthermodynamic constraints in photo-induced charge carriers for subminute water\ndisinfection under real. In addition, summary tables of results should be added.\nRecycling performance should be performed. Add new references. The content is not\nwellcategorized.\nResponse: Thank you very much for your constructive comments and valuable\nguidance on our work.After several months of careful consideration and revision, we\nhave made substantial improvements to the manuscript. With your valuable guidance,\nwe believe that the overall quality of the manuscript has been greatly enhanced\nrelative to the earlier version. We sincerely appreciate your valuable suggestions, as\nthey have not only contributed to the improvement of this manuscript, but also\nprompted us, in the process of addressing them one by one, to systematically\nreorganize and reflect more deeply on the relevant principles. This has allowed us to\ngain a more thorough and solid understanding of the underlying concepts and to\nachieve a morerigorous and comprehensive grasp oftherelevant knowledge system.\n1.Pleasewritethename ofthe process(photocatalytic activity)inthetitle.\nResponse: Thanks for the comment. We have revised the title as suggested.\nPleasesee thetitlepage intherevised manuscript.\n2. Write the name of the synthesized compound in the title of the article and\nKeywords.\nResponse: We appreciate the reviewer’s suggestion. However, we are concerned\nthat including the full name of the synthesized compound (phosphorene\nnanoflakes/BiOI nanosheets heterojunction) in the title would make it excessively\nlengthy. Instead, we have explicitly listed both components in the Keywords section,\nas you suggested. We hope this arrangement is acceptable, and we would be glad to\nfurther adjust it if the reviewer deems it necessary. Please see page 1 lines 21-22 in\ntherevised manuscript as follows:\nKeywords: water disinfection; photocatalysis; heterojunction; phosphorene\nnanoflakes; BiOI nanosheets\n3. This sentence “Additionally, the developed catalyst can be incorporated into a\ncontinuous-flow fixed-bed reactor, sustaining water purification for up to 24 h,\ndemonstrating its potential for practical POU disinfection applications.” can be\ndeleted fromABSTRACTandwritten inthe conclusion section.\nResponse: Thanks for the comment. The sentence has been removed from the\nAbstract section and appropriately placed intheConclusion section as advised.\n4.InABSTRACT,you can writeyour analysis techniques (XRD, EIS,…).\nResponse: Thanks for the comment. The key analysis technique has been added\nto the Abstract section as recommended. Please see page 1 lines 8-15 in the revised\nmanuscript as follows:\nHere, we use phosphorene nanoflakes (PNs) and BiOI nanosheets (BS) as model\nmaterials to construct a heterojunction, illustrating that simultaneously modulating the\ninterfacial interaction and band alignment between the heterojunction components can\nachieve a dual optimization of the kinetic and thermodynamic constraints in\nphoto-induced charge carriers (as confirmed by advanced characterizations, e.g.,\nfemtosecond transient absorption spectroscopy), effectively enhancing the utilization\nofvisible-spectrum energy for microbial inactivation.\n5. The words pathogens, with waterborne gastroenteritis are specialized biological\nwords.Can you replacethemwith anothersentence?\nResponse: We appreciate the reviewer’s suggestion. The terms “pathogens” and\n“waterborne gastroenteritis” have been replaced with more easily understood words.\nPleasesee page 2lines26-28 in therevised manuscript as follows:\nIn these regions, up to 80% of diseases can be traced to waterborne microorganisms,\nwithdiarrheal diseases alone accounting forover 480,000deaths annually [3,4].\n6.Writethe relationshipbetween POUandSODIS.\nResponse: Revised as suggested. Please see page 1 lines 2-4 in the revised\nmanuscript as follows:\nSolar disinfection, as a point-of-use (POU) water disinfection strategy for controlling\nwaterborne microorganisms, serves millions of residents daily in over 50 low- to\nmiddle-incomecountries lacking basic drinkingwater services.\n7.Intheintroduction, you can writemorespecialized information about your work.\nResponse: Thanks for the comment. We have added more specialized\ninformation about our latest research work in the Introduction section as\nrecommended (Water Research. 2026, 288, 124558). Please see page 3 lines 52-55 in\nthe revised manuscript as follows:\nThese ROS can subsequently disrupt the essential macromolecules of pathogens,\naffecting multiple levels such as membrane integrity and metabolism, antioxidant\nenzyme activity, and genetic material, thereby accelerating their photoinactivation\n[8-10].\n[10] Zhou,Y., He, D., Lei,Y., Leung, K. S., Zhang,Y., Qu, J.,Yang, X. Bacterial inactivation by\ndichloride radical in water: Molecular-level reaction kinetics and disinfection mechanism. Water.\nRes.288,124558(2026).\n8.Pleasewriteabout bismuth-based compounds (properties, applications).\nResponse: Thanks for your suggestion. In the revised version, we have added a\nsummary of the fundamental physicochemical properties of bismuth oxyhalides\n(BiOX, X = Cl, Br, I) in the Supporting Information. Please see page 1 in the revised\nSupportingInformation as follows:\nBismuth oxyhalides (BiOX, X = Cl, Br, I) are a class of V−VI−VII ternary oxide\nsemiconductors characterized by a layered tetragonal matlockite structure, in which\npositively charged [Bi O ] slabs alternate with double halogen layers and are held\n2 2\ntogether through weak van der Waals forces [4]. BiOX exhibit several advantageous\nphysicochemical properties: (i) an indirect bandgap, where the k-space displacement\nhinders the direct recombination of electrons and holes, (ii) an intrinsic internal\nelectric field along the (001) orientation, facilitating efficient charge separation [4].\nOwing to these attributes, BiOX compounds have been investigated for various\nphotocatalytic processes, including water purification and N fixation [5, 6]. Among\n2\nthe BiOX family, BS (BiOI is generally present in the form of nanosheets) possess the\nnarrowest bandgap, which generally translates into enhanced photocatalytic\nperformance undervisible-light irradiation [7].\nIn addition, for BS specifically, we have experimentally characterized the\nphysicochemical properties that are most relevant to its photocatalytic behavior in the\nmain text. For example, for the charge carrier separation efficiency of BS, please see\npages 11-12 lines 208-224 in therevised manuscript as follows:\nTo validate this, the charge carrier separation efficiencies of 0.0PNs/BS and\n0.8PNs/BS are systematically investigated using a range of characterization\ntechniques. First, transient photo-current (TPC) response measurement is conducted.\nAs depicted in Figure S12a, the TPC response of 0.8PNs/BS, which is significantly\nhigher than that of 0.0PNs/BS, suggests an improved efficiency in the separation of\nelectron-hole pairs upon the incorporation of PNs with BS. Additionally, the results\nfrom electrochemical impedance spectroscopy (EIS) measurement demonstrate a\nsmaller semicircle radius in the Nyquist plot of 0.8PNs/BS compared with that of\n0.0PNs/BS, implying a reduced charge transfer resistance for 0.8PNs/BS, thereby\npromoting more efficient charge carrier separation (Figure S12b). Furthermore, the\nsteady-state photoluminescence (PL) results of the samples reveal a reduced PL\nintensity for 0.8PNs/BS in contrast to 0.0PNs/BS, suggesting a suppressed charge\ncarrier recombination in 0.8PNs/BS (Figure S12c). Moreover, the transient-state PL\nresults shown in Figure S12d exhibit an increase in the average PL lifetime decay,\nfrom 19.8ns for 0.0PNs/BS to 23.9ns for 0.8PNs/BS.This further supports the higher\nelectron-hole separation efficiency of 0.8PNs/BS, in agreement with the TPC, EIS,\nand PLresults.\nFigureS12.(a)TPC,(b)EIS,(c)steady-statePL,and(d)transient-statePLresultsof0.0PNs/BS\nand0.8PNs/BS.\nFor the band structure of BS, please see pages 12-13 lines 237-244 in the revised\nmanuscript as follows:\nFirst, the E of BS is derived from the plot of (αhν)n versus hν shown in Figure S13a,\ng\nwhere α represents absorption coefficient, h stands for Planck constant, and ν denotes\nlight frequency [32]. In this equation, n is set to 1/2 due to the indirect bandgap nature\nof BS. Consequently, the determined E value of BS stands at 1.68 eV. Subsequent to\ng\nthis, XPS valence-band spectroscopy analysis is conducted for BS. As illustrated in\nFigure S13b, the valence-band value of BS is observed to be ~1.36 V versus NHE.\nThis leads to the calculation of the conduction-band value of BS, which is found to be\n−0.32Vversus NHE (Table S1).\nFigureS13.(a)(αhν)nversushνcurveand(b)XPSvalence-bandspectrumofBS.(c)UV-vis\nabsorbancespectrumand(d)Mott-SchottkyplotofPNs(theconduction-bandvalueofPNsis\n−1.05VversusAg/AgCl,correspondingto−0.44VversusNHE).\nTableS1.E valuesandbandedgepositionsoftheheterojunctioncomponents.\ng\nComponent E value(eV) Valenceband(V) Conductionband(V)\ng\nBS 1.68 1.36 −0.32\nPNs 1.70 1.26 −0.44\n9.Pleasewriteabout theadvantages anddisadvantages ofwater disinfection.\nResponse: Thanks for your suggestion. For the advantages of photocatalytic water\ndisinfection, please see page 3lines 47-55 intherevised manuscript as follows:\nGenerally, a photocatalyst with an appropriate bandgap can harness visible light to\ngenerate electron-hole pairs, which initiate redox reactions to produce reactiveoxygen\nspecies (ROS). Theoretically, the redox potentials relevant to ROS formation are\n−0.33 V (O /•O −) and 0.28 V (O /H O ) for electron-driven oxygen reduction, and\n2 2 2 2 2\n1.78 V (H O/•OH) for hole-driven water oxidation, all referenced to NHE [7, 8].\naffecting multiple levels such as membrane integrity and metabolism, antioxidant\nenzyme activity, and genetic material, thereby accelerating their photoinactivation\n[8-10].\nFor the disadvantages of photocatalytic water disinfection, please see page 3\nlines 59-62 in therevised manuscript as follows:\nHowever, the effective utilization of absorbed visible light for microbial inactivation\nrequires the simultaneous reduction of energy losses in the processes of charge carrier\ntransfer and their generation of ROS, a challenge that currently-available\nheterojunctionsfail toaddress.\n10. Explain the relationship between redox reactions and subsequently disrupt the\nessential macromolecules of pathogens.\nResponse: We thank the reviewer for the comment. During the photocatalytic\nprocess, redox reactions generate ROS, which subsequently disrupt the essential\nmacromolecules of pathogens, leading to their inactivation. Please see page 3 lines\n47-55in therevised manuscript as follows:\nGenerally, a photocatalyst with an appropriate bandgap can harness visible light to\ngenerate electron-hole pairs, which initiate redox reactions to produce reactiveoxygen\nspecies (ROS). Theoretically, the redox potentials relevant to ROS formation are\n−0.33 V (O /•O −) and 0.28 V (O /H O ) for electron-driven oxygen reduction, and\n2 2 2 2 2\n1.78 V (H O/•OH) for hole-driven water oxidation, all referenced to NHE [7, 8].\naffecting multiple levels such as membrane integrity and metabolism, antioxidant\nenzyme activity, and genetic material, thereby accelerating their photoinactivation\n[8-10].\n11. Draw the Graphical Abstract (A graphical abstract is a single image that visually\nrepresentsall thekey aspects andmessages of your work).\nResponse: Thanks for your suggestion. The graphical abstract has been prepared as\nrequested. Pleasesee it below:\n12. This sentence “(ii) the limited redox capabilities of charge carriers prevent the\nsufficient generation of ROS, resulting in energy loss from a thermodynamic\nperspective” is examined in terms of what thermodynamic point of view and\nthermodynamic parameters?\nResponse: We thank the reviewer for the comment. From a thermodynamic\nperspective, the generation of ROS during photocatalysis is governed by the redox\npotentials of the relevant reactions relative to the semiconductor’s conduction and\nvalence band edges. If the conduction band minimum or valence band maximum of\nthe photocatalyst does not possess sufficient potential to drive the desired redox\nreactions, the formation of ROS is thermodynamically limited, leading to energy loss.\nAs you noted, the relevant thermodynamic parameters essentially correspond to\nwhether the semiconductor’s conduction and valence band edges are sufficiently\npositioned to drive the desired redox reactions. In response, we have supplemented\nthe manuscript with the corresponding analysis. Please see page 3 lines 50-52 in the\nrevised manuscript as follows:\nTheoretically, the redox potentials relevant to ROS formation are −0.33 V (O /•O −)\n2 2\nand 0.28 V (O /H O ) for electron-driven oxygen reduction, and 1.78 V (H O/•OH)\n2 2 2 2\nforhole-driven water oxidation,all referenced to NHE [7,8].\n13. In the introduction, use the topic (Nanomaterials are categorized into 0D, 1D, 2D\nand3Dbased ontheir nanostructures)andwritesome content.\nResponse: Revised as suggested. Please see page 4 lines 76-79 in the revised\nmanuscript as follows:\nOn one hand, both PNs and BS possess a 2D nanostructure, enabling them to form\nintimate “face to face” contacts with robust interfacial interactions for fast charge\ncarrier transfer (2D/2D heterojunctions provide larger interfacial contact areas than\nothercounterparts, e.g., 0D/2Dor 2D/3D).\n14.What happens in thedarkphase ofthe photocatalyticprocess?\nResponse: Thanks for the comment. In the dark phase of the photocatalytic\nprocess, no significant reaction occurs. This has been confirmed both by previous\nreports and by our own experiments. This work has also examined the reaction under\ndark conditions, please see pages 15-16 lines 302-307 in the revised manuscript as\nfollows:\nIn contrast, control experiments conducted under solely visible-light exposure or in\nthe presence of 0.8PNs/BS under a dark condition result in disinfection efficiencies\nbelow 0.25 log after 120 min, demonstrating that bacterial inactivation is attributed to\nvisible-light photocatalysis (0.8PNs/BS can harvest the entire visible-light spectrum,\nas evidenced byUV-vis diffusereflectance spectroscopy) (FigureS16).\nFigure S16. (a) Dark and (b) light control experiments. (c) UV-vis diffuse reflectance\nspectroscopyresultsofthesamples.\n15.Pleasewriteabout bismuth-based compounds (properties, applications).\nResponse: Thanks for your suggestion. In the revised version, we have added a\nsummary of the fundamental physicochemical properties of bismuth oxyhalides\n(BiOX, X = Cl, Br, I) in the Supporting Information. Please see page 1 in the revised\nSupportingInformation as follows:\nBismuth oxyhalides (BiOX, X = Cl, Br, I) are a class of V−VI−VII ternary oxide\nsemiconductors characterized by a layered tetragonal matlockite structure, in which\npositively charged [Bi O ] slabs alternate with double halogen layers and are held\n2 2\ntogether through weak van der Waals forces [4]. BiOX exhibit several advantageous\nphysicochemical properties: (i) an indirect bandgap, where the k-space displacement\nhinders the direct recombination of electrons and holes, (ii) an intrinsic internal\nelectric field along the (001) orientation, facilitating efficient charge separation [4].\nOwing to these attributes, BiOX compounds have been investigated for various\nphotocatalytic processes, including water purification and N fixation [5, 6]. Among\n2\nthe BiOX family, BS (BiOI is generally present in the form of nanosheets) possess the\nnarrowest bandgap, which generally translates into enhanced photocatalytic\nperformance undervisible-light irradiation [7].\nIn addition, for BS specifically, we have experimentally characterized the\nphysicochemical properties that are most relevant to its photocatalytic behavior in the\nmain text. For example, for the charge carrier separation efficiency of BS, please see\npages 11-12 lines 208-224 in therevised manuscript as follows:\nTo validate this, the charge carrier separation efficiencies of 0.0PNs/BS and\n0.8PNs/BS are systematically investigated using a range of characterization\ntechniques. First, transient photo-current (TPC) response measurement is conducted.\nAs depicted in Figure S12a, the TPC response of 0.8PNs/BS, which is significantly\nhigher than that of 0.0PNs/BS, suggests an improved efficiency in the separation of\nelectron-hole pairs upon the incorporation of PNs with BS. Additionally, the results\nfrom electrochemical impedance spectroscopy (EIS) measurement demonstrate a\nsmaller semicircle radius in the Nyquist plot of 0.8PNs/BS compared with that of\n0.0PNs/BS, implying a reduced charge transfer resistance for 0.8PNs/BS, thereby\npromoting more efficient charge carrier separation (Figure S12b). Furthermore, the\nsteady-state photoluminescence (PL) results of the samples reveal a reduced PL\nintensity for 0.8PNs/BS in contrast to 0.0PNs/BS, suggesting a suppressed charge\ncarrier recombination in 0.8PNs/BS (Figure S12c). Moreover, the transient-state PL\nresults shown in Figure S12d exhibit an increase in the average PL lifetime decay,\nfrom 19.8ns for 0.0PNs/BS to 23.9ns for 0.8PNs/BS.This further supports the higher\nelectron-hole separation efficiency of 0.8PNs/BS, in agreement with the TPC, EIS,\nand PLresults.\nFigureS12.(a)TPC,(b)EIS,(c)steady-statePL,and(d)transient-statePLresultsof0.0PNs/BS\nand0.8PNs/BS.\nFor the band structure of BS, please see pages 12-13 lines 237-244 in the revised\nmanuscript as follows:\nFirst, the E of BS is derived from the plot of (αhν)n versus hν shown in Figure S13a,\ng\nwhere α represents absorption coefficient, h stands for Planck constant, and ν denotes\nlight frequency [32]. In this equation, n is set to 1/2 due to the indirect bandgap nature\nof BS. Consequently, the determined E value of BS stands at 1.68 eV. Subsequent to\ng\nthis, XPS valence-band spectroscopy analysis is conducted for BS. As illustrated in\nFigure S13b, the valence-band value of BS is observed to be ~1.36 V versus NHE.\nThis leads to the calculation of the conduction-band value of BS, which is found to be\n−0.32Vversus NHE (Table S1).\nFigureS13.(a)(αhν)nversushνcurveand(b)XPSvalence-bandspectrumofBS.(c)UV-vis\nabsorbancespectrumand(d)Mott-SchottkyplotofPNs(theconduction-bandvalueofPNsis\n−1.05VversusAg/AgCl,correspondingto−0.44VversusNHE).\nTableS1.E valuesandbandedgepositionsoftheheterojunctioncomponents.\ng\nComponent E value(eV) Valenceband(V) Conductionband(V)\ng\nBS 1.68 1.36 −0.32\nPNs 1.70 1.26 −0.44\n16. You have written this sentence: This gives a first-order disinfection rate ~221\ntimes higher than thatof commercialP25 TiO )several times. Please correct it.\nbeen removed from themanuscript.\n17. Provide a table of the history of published articles related to the topic of your\nwork.\nResponse: Thanks for your suggestion. As suggested, we have provided a table\nsummarizing the most representative studies related to the topic of our work. In\naddition, we have included a comparative figure alongside the table to benchmark the\ndisinfection performance of our work against these works. Please see pages 17-18\nlines 331-344in therevised manuscript as follows:\nThe antibacterial performance of 0.8PNs/BS, with a 7-log inactivation of E. coli\nwithin 5 min under visible-light illumination, is considered one of the most\nremarkable based on a thorough review of the existing literature, particularly in terms\nof the extent of the log reduction in bacterial concentration and the rapidity of\ndisinfection process (Figure 4b and Table S2). Compared with those that achieve a\ncomplete inactivation of E. coli within 30 min, such as (Al O @v-MoS )/Cu,\n2 3 2\nCu-MoS , and F-g-C N -30-EP, the bacterial concentration reduction achieved by\n2 3 4\n0.8PNs/BS surpasses others by 1-2 log. As for disinfection systems containing an\ninitial bacterial concentration of 7 log, the reported antimicrobial materials thus far\nnecessitate a minimum of 60 min to achieve the total inactivation of E. coli, whereas\nthese materials, such as SGO-ZnO-Ag, are accompanied by a certain degree of\nbiological intolerance. To the best of our knowledge, no previously reported\nphotocatalysts have demonstrated such an extraordinary disinfection efficacy when\nconfronted with an initialE. coli concentration of7log.\nFigure 4. (a) Visible-light photocatalytic disinfection activities of PNs/BS materials. (b)\nVisible-light photocatalytic disinfection performance comparison of 0.8PNs/BS with the literature\nvaluesofotherphotocatalysts.TheplotgivestheloginactivationefficiencyofE.coliwithrespect\nto illumination time: (1) 0.8PNs/BS (this work), (2) (Al O @v-MoS )/Cu (ref. 33), (3)\n2 3 2\nSGO-ZnO-Ag (ref. 34), (4) Cu-MoS (ref. 7), (5) F-g-C N -30-EP (ref. 35), (6) CoFe O /HTCC\n2 3 4 2 4\n(ref. 8), (7) g-C N -TiO (ref. 13), (8) BiVO nanotube (ref. 36). (c) Disinfection performance\n3 4 2 4\ncomparison between 0.8PNs/BS and P25 TiO under real-sunlight illumination. (d) Visible-light\n2\nphotocatalyticdisinfectionactivityofacontinuous-flowfixed-bedreactorbasedon0.8PNs/BS.\nTable S2. Visible-light photocatalytic disinfection performance comparison of g-C N -600 with\n3 4\ntheliteraturevaluesofotherphotocatalysts.\nMaterial Bacteriastrain Performance\n0.8PNs/BS E.coliK-12 ~7login5min\n(Al O @v-MoS )/Cu E.coliK-12 ~5.73login3min\n2 3 2\nSGO-ZnO-Ag E.coli ~7login20min\nCu-MoS E.coliK-12 ~5login20min\n3 4\nCoFe O /HTCC E.coliK-12 ~7login60min\n2 4\ng-C N -TiO E.coliK-12 ~7login180min\n3 4 2\nBiVO nanotube E.coliK-12 ~5.3login300min\n4\n18.Pleasewriteabout phosphorenenanoflakes (PNs)(properties, applications).\nResponse: Thanks for your suggestion. In the revised version, we have added a\nsummary of the fundamental physicochemical properties of PNs in the Supporting\nInformation.Please seepage 1in therevised SupportingInformation as follows:\nPNs, known as the few-layer form of BP, have recently garnered significant attention\nowing to the unique physicochemical properties: (i) a high surface-to-volume ratio\nwithabundant accessible activesites; (ii)adistinctivelayer-dependent direct bandgap,\ncoupled with tunable redox properties of charge carriers; (iii) a broad light absorption\ncapacity across the entire visible-light region [2]. Benefiting from these characteristics,\nPNs have been explored in diverse photocatalytic applications, including water\nsplitting, pollutant degradation, and H O production [2, 3].\n2 2\nIn addition, for PNs, we have experimentally characterized the physicochemical\nproperties that are most relevant to its photocatalytic behavior in the main text. For\nexample, for the band structure of PNs, please see page 13 lines 244-252 in the\nrevised manuscript as follows:\nFurthermore, the E of PNs is ascertained through UV-vis absorption spectroscopy\ng\nanalysis.As shown in Figure S13c, the identified absorption edge of PNs at ~731 nm\ncorresponds to an E value of 1.70 eV. We then execute a Mott-Schottky test,\ng\nrevealing the n-type semiconductor characteristic of PNs (Figure S13d). Thus, the\nflat-band potential of PNs, extracted from the Mott-Schottky result, can offer a rough\nestimation for the conduction-band value. Consequently,the conduction-band value of\nPNs is established at −0.44 V versus NHE, and the valence-band value is then\ncalculated tobe1.26Vversus NHE (TableS1).\nFigureS13.(a)(αhν)nversushνcurveand(b)XPSvalence-bandspectrumofBS.(c)UV-vis\nabsorbancespectrumand(d)Mott-SchottkyplotofPNs(theconduction-bandvalueofPNsis\n−1.05VversusAg/AgCl,correspondingto−0.44VversusNHE).\nTableS1.E valuesandbandedgepositionsoftheheterojunctioncomponents.\ng\nComponent E value(eV) Valenceband(V) Conductionband(V)\ng\nBS 1.68 1.36 −0.32\nPNs 1.70 1.26 −0.44\n19.Whydid you chooseBiOI- BiOBr or BiOCl?\nResponse: Thanks for the comment. We chose BiOI, BiOBr, and BiOCl because\nour study aims to demonstrate that optimizing the compatibility between the\nmacroscopic geometric structures of heterojunction components can effectively\novercome the kinetic constraint in photo-induced charge carrier. PNs have a typical\n2D structure, and all members of the BiOX (X = I, Br, Cl) family likewise crystallize\nin2D layered structures, making themsuitable candidates to probethis concept.\nThe core of this work is to investigate 2D/2D heterojunctions (composed of BS\nand PNs) to demonstrate the underlying scientific hypothesis. To further validate the\nhypothesis, it is desirable to examine other 2D/2D materials. However, if the second\n2D component differs too much in intrinsic properties—such as using carbon nitride\nwith very different band structure and surface chemistry—the results could be\ndominated by these property mismatches, making it difficult to isolate the effect of\n2D/2D structural compatibility itself. In contrast, selecting chemically and structurally\nsimilar materials like BiOBr or BiOCl preserves comparable electronic and surface\ncharacteristics while maintaining the 2D morphology. This allows a more direct and\nconvincing demonstration that the observed enhancements arise from geometric and\ninterfacial compatibility, rather than other confounding material differences. For the\nphotocatalytic ROS generation and bacterial inactivation over PNs/BiOBr and\nPNs/BiOCl,please see pages 31-32 in therevised SupportingInformation as follows:\nFigure S20. (a) Visible-light photocatalytic disinfection activities of BiOBr and PNs/BiOBr\nheterojunctions toward E. coli. Steady-state concentrations of (b) •O −, (c) 1O , and(d) •OH for\n2 2\nBiOBrandPNs/BiOBrphotocatalyticsystems.(e)AccumulatedconcentrationsofH O forBiOBr\n2 2\nandPNs/BiOBrphotocatalyticsystems.\nFigure S21. (a) Visible-light photocatalytic disinfection activities of BiOCl and PNs/BiOCl\nheterojunctions toward E. coli. Steady-state concentrations of (b) •O −, (c) 1O , and(d) •OH for\n2 2\nBiOClandPNs/BiOClphotocatalyticsystems.(e)AccumulatedconcentrationsofH O forBiOCl\n2 2\nandPNs/BiOClphotocatalyticsystems.\n20. Does the layered structure of bismuth compounds contribute to their\nphotocataliticactivity?\nResponse: Thanks for the comment. You are correct. The morphology of BiOX\nplays a crucial role in the photocatalytic disinfection performance of the resulting\ncomposites. Before the systematic study in this work, we conducted a series of\npreliminary experiments. When layered BiOI was combined with PNs, the complete\ninactivation of 7 log bacteria could be achieved under visible-light irradiation within 5\nmin. In contrast, when spherical BiOI was used, the same level of bacterial\ninactivation required at least 1 h. These results clearly demonstrate that the layered\nstructure significantly enhances the photocatalytic efficiency of the obtained\nmaterials.\n21.Explain moreabout theeffects of compound morphology ontheprocess.\nResponse: Thanks for the comment. The compatibility between the macroscopic\ngeometries of the heterojunction components primarily enables the formation of\nintimate “face-to-face” contacts with strong interfacial interactions. This was\nconfirmed through XANES characterization. Please see page 9 lines 172-178 in the\nrevised manuscript as follows:\nThe observed “face to face” contact between the two 2D components, PNs and BS,\nwithin the constructed heterojunction, is anticipated to create a strong interfacial\ninteraction between the layers. To confirm this, synchrotron-based X-ray absorption\nnear-edge structure (XANES) analysis is employed. The Bi L -edge absorption edge\n3\nposition of 0.8PNs/BS shows a negative shift compared to that of 0.0PNs/BS,\nsuggesting the occurrence of electron transfer from PNs to BS within the\nheterojunction(Figure2a).\n22.How manyallotropes does phosphorus have?\nResponse: Thanks for the comment. Phosphorus has several allotropes, the most\ncommon being white, red, and black phosphorus. Among these, black phosphorus is\nthe thermodynamically most stable form. Please see page 1 in the revised Supporting\nInformationas follows:\nElemental phosphorus occurs in several allotropes, including white, red, and black\nphosphorus (BP), withBPbeingthemost thermodynamically stable form [1].\n23.Writethe properties of BP.\nResponse: Revised as suggested. Please see page 1 in the revised Supporting\nInformationas follows:\nElemental phosphorus occurs in several allotropes, including white, red, and black\nphosphorus (BP), with BP being the most thermodynamically stable form [1]. PNs,\nknown as thefew-layer form ofBP, have recently garnered significant attention owing\nto the unique physicochemical properties: (i) a high surface-to-volume ratio with\nabundant accessible active sites; (ii) a distinctive layer-dependent direct bandgap,\ncoupled with tunable redox properties of charge carriers; (iii) a broad light absorption\ncapacity across the entire visible-light region [2]. Benefiting from these characteristics,\nPNs have been explored in diverse photocatalytic applications, including water\nsplitting, pollutant degradation, and H O production [2, 3].\n2 2\n24. Did you do part of the Synthesis of bulk BP (hydrothermally purified for 10 hours\nat200°C to removeoxide layers)?\nResponse: Thanks for the comment. We did not perform this step. Based on our\nexperience, the hydrothermal purification at 200℃ for 10 h is more suitable for red\nphosphorus rather than the BP used in our work (Environmental Science &\nTechnology.2015,49,6264-6273).\n25.Whydid you choosethe temperatureofmufflefurnace 600?\nResponse: Thanks for the comment. We chose 600℃ based on extensive prior\nresearch in our group on BP synthesis. Through systematic optimization, this\ntemperature was found to be most favorable for obtaining high-quality BP crystals.\n(Chemical Engineering Journal. 2020, 384, 123258). The choice of this synthesis\ncondition is now supported by literature. Please see page 3 in the revised Supporting\nInformationas follows:\nA bulk BP crystal was synthesized in accordance with a previously established\nprocedure [8].\n26.Does calcination temperatureandtimehave anyeffect onmorphology?\nResponse:Thanks for the comment. In the synthesis of BP,temperature primarily\nserves to ensure that the starting materials (red phosphorus, iodine, and tin) can\nsublimate and react, forming the P-Sn-I compounds that act as nucleation sites. The\nheating and cooling process mainly controls the sequential stages of red phosphorus\ngas generation, deposition, and crystallization.As long as the temperature is sufficient\ntoenable complete sublimation of red phosphorus and interaction with themineralizer,\nthe overall morphology of BP does not fundamentally change. Therefore, temperature\nis not the sole determinant of morphology but must meet the basic requirements for\nprecursor sublimation and mineralizer-assisted growth. Given the extensive studies on\nBP synthesis and the fact that our group has already identified a suitable preparation\nmethod, this aspect is not the primary focus of the present work (Crystal Growth\nDesign.2016,16,1096-1103).\n27.Whydid you investigatetheroleof solvents? What is themost important point?\nResponse: We appreciate the reviewer’s comment. Unlike most 2D nanosheet\nmaterials, PNs are generally obtained by first synthesizing bulk crystals, which are\nthen exfoliated into nanosheets. The most common approach for this exfoliation is\nliquid-phase exfoliation. Therefore, the choice of solvent is crucial, as it directly\naffects the efficiency of exfoliation. Theoretically, efficient exfoliation can be\nachieved when the surface energy of the solvent matches with that of the material,\nbecause the enthalpy of the mixed system is minimized according to the equation of\nΔH /V ≈ 2(δ - δ )2φ/T (ΔH, V , δ, φ, and T are the enthalpy of mixing,\nmix mix G sol bulk mix bulk\nvolume of the dispersion, square root of the component surface energy, nanosheet\nvolume fraction, and average thickness of the nanosheet, respectively) (Nature\nNanotechnology. 2008, 3, 563-568). Please see pages 12-13 in the revised Supporting\nInformationas follows:\nLiquid exfoliation process generally involves dispersing bulk materials in a selected\nexfoliating medium and utilizing the energy from ultrasonication to disrupt the van\nder Waals force between the layers of bulk materials, thus obtaining few-layer 2D\nmaterials. This method does not require harsh chemical treatments or high\ntemperatures, which makes it widely adopted. During the exfoliation process, the\nchoice of exfoliating medium plays a crucial role in determining the quality of\nproduct. Theoretically, achieving efficient exfoliation is contingent on matching the\nsurface energy of solvent with that of material. This condition minimizes the enthalpy\nof the mixed system, as described by the equation ofΔH /V ≈ 2(δ − δ )2φ/T ,\nmix mix G sol bulk\nwhere ΔH, V , δ, φ, and T represent the enthalpy of mixing, the volume of\nmix bulk\ndispersion, the square root of component surface energy, the volume fraction of\nnanosheet, and theaverage thickness ofnanosheet, respectively [12, 13].\n28.What isthe advantageof themethod ultrasonicexfoliation process?\nResponse: We appreciate the reviewer’s comment. We have added relevant\ndiscussion.Pleasesee page 12in therevised Supporting Information as follows:\nThis method does not require harsh chemical treatments or high temperatures, which\nmakes it widely adopted.\n29.What isthe roleof ice-bath sonication in synthesis?\nResponse: Thanks for the comment. During our synthesis, prolonged ultrasonic\ntreatment in a water bath can lead to a rise in temperature. To maintain a stable and\ncontrolled temperature throughout the sonication, we employed an ice bath. Based on\nyour comment, we have revised the relevant content to enhance readability. Please see\npage 5intherevised Supporting Information asfollows:\nSubsequently, the obtained dispersion underwent a further ice-bath sonication for 2 h\n(thepurpose ofice bath istomaintain aconstant temperature).\n30. What solvent (Ethylene glycol or Ethanol, … ) was used in the synthesis of BiOX\n(X = I, Br,Cl)?\nResponse: Thanks for the comment. All of these BiOX materials were\nsynthesized in aqueous solution. Based on your comment, we have revised the\nrelevant content. Please see page 5-6 in the revised Supporting Information as\nfollows:\nSynthesis of BS\nBS were synthesized using a well-established protocol. In a standard procedure, both\n35 mL of KI (11.4 mM) and 35 mL of Bi(NO ) ·5H O (11.4 mM) were prepared as\n3 3 2\naqueous solutions and then mixed. The resulting mixture was stirred for 1 h at room\ntemperature. Following this, the mixture was heated at 80℃ for 4 h in a\nprogrammable temperature chamber. The resulting materials were collected through\nsuction filtration andsubsequently dried inan oven at 60℃,yielding BS.\nSynthesis of BiOBr andBiOClnanosheets\nBiOBr nanosheets were synthesized using a method analogous tothesynthesis of\nBS, except that KI was replaced by 35 mLof KBr (11.4 mM). BiOCl nanosheets were\nsynthesized using a method analogous to the synthesis of BS, except that KI was\nreplaced by35mLofKCl (11.4mM).\n31.Whywas 35mLof KI(11.4 mM) used? Whydidn’t you usetheprecursor BiCl ?\n(11.4 mM) was chosen to ensure the stoichiometric balance with 35 mL of\nBi(NO ) ·5H O (11.4 mM). Using KI allows precise control over the halide source\n3 3 2\nand ensures reproducible crystal growth, which is a well-established protocol for the\npreparation ofBS.Therefore, we didnot choose otherchemicals.\n32. Did you calculate the band gap energy of BS using the DFT method? Because of\nthis sentence (This indicates that the control over the layer number of PNs is more\nnecessarycomparedtoBS.)\nResponse: Thanks for the comment. You are correct in your observation. We did\nnot perform DFT calculations of the bandgap energy for BS, as this has already been\ncomprehensively reported in earlier literature (RSC Advance. 2017, 7: 24446-24452).\nNotably, the bandgap energy of BS exhibits only negligible variation with layer\nnumber (typically within ~0.1 eV for 1-5 layers), in sharp contrast to the pronounced\nlayer dependence observed in PNs. This weak layer dependence arises from the\nelectronic structure of BiOI, where the states near the band edges are predominantly\ncontributed by Bi-6p and O-2p/I-5p orbitals, and the interlayer coupling remains\nrelatively weak. As a result, thinning BS to few-layer or even monolayer form does\nnotlead to substantial bandgapmodulation comparable tothat in PNs.\n33. Why do commonly used stripping solvents such as NMP, acetone, ethanol,\nisopropanol (IPA), and dimethylformamide (DMF) prevent minimizing the enthalpy of\nthemixed system? What parameters areinfluential?\nResponse: Thanks for the comment. Theoretically, efficient liquid-phase\nexfoliation requires a close match between the surface energy of the solvent and that\nof the layered material. Under this condition, the enthalpy of mixing can be\nminimized,as described bytherelation:\nΔH /V ≈ 2(δ − δ )2φ/T\nmix mix G sol bulk\nWhere ΔH, V ,δ, φ, and T represent the enthalpy of mixing, the volume of\nmix bulk\ndispersion, the square root of component surface energy, the volume fraction of\nnanosheet, and the average thickness of nanosheet, respectively (Science. 2011, 331:\n568-571).\nIn practice, commonly used solvents such as NMP, acetone, ethanol, IPA, and\nDMF often do not perfectly match the surface energy of specific 2D materials like\nPNs. This mismatch increases the enthalpy of mixing, thereby reducing exfoliation\nefficiency.\n34.Introducethisparameter (ΔH,Vmix, δ,φ,andTbulk).\nResponse: Thanks for the comment. ΔH, V , δ, φ, and T represent the\nmix bulk\nenthalpy of mixing, the volume of dispersion, the square root of component surface\nenergy, the volume fraction of nanosheets, and the average thickness of nanosheets,\nrespectively.Please see pages 12-13 intherevised Supporting Information as follows:\nLiquid exfoliation process generally involves dispersing bulk materials in a selected\nexfoliating medium and utilizing the energy from ultrasonication to disrupt the van\nder Waals force between the layers of bulk materials, thus obtaining few-layer 2D\nmaterials. This method does not require harsh chemical treatments or high\ntemperatures, which makes it widely adopted. During the exfoliation process, the\nchoice of exfoliating medium plays a crucial role in determining the quality of\nproduct. Theoretically, achieving efficient exfoliation is contingent on matching the\nsurface energy of solvent with that of material. This condition minimizes the enthalpy\nof the mixed system, as described by the equation ofΔH /V ≈ 2(δ − δ )2φ/T ,\nmix mix G sol bulk\nwhere ΔH, V , δ, φ, and T represent the enthalpy of mixing, the volume of\nmix bulk\ndispersion, the square root of component surface energy, the volume fraction of\nnanosheet, and theaverage thickness ofnanosheet, respectively [12, 13].\n35.Increasethefont of Raman spectra ofbulkBPandPNs.\nResponse: Thanks for your suggestion. The font size of the Raman spectra for\nbulk BP and PNs has been increased accordingly in the revised Supporting\nInformationas follows:\nFigureS3.(a)Selected-areaelectrondiffractionofPNs.(b)RamanspectraofbulkBPandPNs.\n36. Check again the Raman peak at 362 cm−1 is attributed to the out-of-plane\nvibrationmodeA1.\nResponse: Thanks for your suggestion. We have rechecked this assignment by\nconsulting multiple prior studies, and confirmed that the attribution of the Raman\npeak at 362 cm−1 to the out-of-plane vibrational mode A1 is accurate and widely\ng\naccepted in the literature (Nano Letters. 2017, 17, 4311-4316; Advanced Energy\nMaterials.2017,7,1700396).\n37. Please write the JCPS standard card and Miller Index for (a) 0.0PNs/BS,\n(b) BP, and0.8PNs/BS.\nResponse: Thanks for your suggestion. Revised as requested, please see page 16\ninthe revised Supporting Information as follows:\nFigureS5.XRDpatternsof(a)0.0PNs/BS,(b)BP,and0.8PNs/BS.\n38.Add theFESEM imageof thecompounds in thearticle. Explain FigureS4more.\nResponse:Thanks for your suggestion. Wehave provided the SEM images of BS,\nBP, and PNs/BS samples. Please see pages 17-18 in the revised Supporting\nInformationas follows:\nFigureS6.SEMimagesofBP.\nFigureS7.SEM images of(a) BSand(b) 0.8PNs/BS(theextremely lowPNs loadingof 0.8wt%\nprecludestheirclearobservationintheSEMimage).\nAs for Figure S4, we have provided a detailed description in the main text of the\nmanuscript. Please seepage 7lines 130-133in therevised manuscript as follows:\nAs depicted in Figure S4, the vertical extent data extracted along the marked line\nreveal a thickness of 1.7-2.1 nm, which corresponds to 2-3 atomic layers, confirming\nthesuccessful productionof ultrathinPNs [29].\n39. What are the results of the thickness measurement? How did you draw this graph\nbyAFM ?(FigureS4-b)\nResponse:Thanks for the comment. For theresults of the thickness measurement,\nplease seepage 7lines 130-133in therevised manuscript as follows:\nAs depicted in Figure S4, the vertical extent data extracted along the marked line\nreveal a thickness of 1.7-2.1 nm, which corresponds to 2-3 atomic layers, confirming\nthesuccessful productionof ultrathinPNs [29].\nThe thickness is measured using Gwyddion, an open-source software specifically\ndesigned for the analysis of scanning probe microscopy data. The software enables\nquantitative extraction of nanosheet thickness by analyzing the height profiles\nobtained fromAFM images.\n40. How do you prove this (002) BP face and (110) BiOI face in the HRTEM image\n(Fig. 1d)?\nResponse: Thanks for the comment. Weconfirmed the lattice planes in Figure 1d\nby analyzing the high-resolution TEM image with Digital Micrograph software. The\nlattice spacings were measured and then compared with the standard crystallographic\ndata. The interplanar distance of ~0.22 nm corresponds well to the (002) plane of BP,\nwhile the spacing of ~0.28 nm matches the (110) plane of BiOI. This assignment is\nconsistent with the JCPDS reference patterns of BP and BiOI, allowing us to reliably\nidentify therespectivecrystal faces intheheterojunction.\n41.Pleasechange XPS spectra, forexample, examine theBSseparately.\nResponse: Thanks for your suggestion. Following your advice, we have\nconducted XPS measurement for BS and carried out a detailed analysis. The\ncorresponding spectra are provided as follows:\nFigureR1.XPSspectraof(a)Bi4f,(b)O1s,and(c)I3dforBS.\nIt is clear that, our results are highly consistent with previously reported data in\ntheliterature, and nonew or distinctivefeatures can be observed. Considering this, we\nbelieve that a detailed discussion related to the XPS results of BS may distract readers\nfrom thecentral focus ofthis work. Forthis reason, we have not included thesedata in\nthemain text.Wekindlyask foryour understanding and approval of thisarrangement.\n42.What does theaccumulation oflines in Figure2.(e),(f) indicate?\nResponse: Thanks for the comment. The data of Figure 2e and f can probe the\nultrafast dynamics of photo-excited charge carriers in 0.8PNs/BS system. By\nmonitoring ΔA over timescales from 0.5 ps to 3 ns, this technique allows us to\ndistinguish different processes: early-time positive signals reflect excited-state\nabsorption and carrier generation, while later-time negative signals correspond to\nground-state bleaching and stimulated emission, revealing carrier relaxation and\nrecombination. Importantly, the comparison between 0.0PNs/BS and 0.8PNs/BS\ndemonstrates enhanced stimulated emission in the latter, indicating more efficient\ncharge transfer across the heterojunction. Therefore, these data provide direct\nevidence of how the heterojunction affects charge separation and recombination\ndynamics, which is crucial for understanding and optimizingphotocatalyticactivity.\n43.Does thenumber of layers have anyeffect ontheresultsof (XANES)analysis?\nResponse: Thanks for the comment. To address your comment, we have\nundertaken a systematic study on this aspect, and our conclusions are summarized as\nfollows: The number of layers of PNs in the heterostructure is not expected to\nsignificantly affect the qualitative conclusions drawn from XANES analysis. XANES\nprobes theunoccupied electronic states and local coordination environment of specific\nelements, which primarily reflects the chemical interaction and charge transfer\nbetween PNs and BS. While the absolute intensity of some features might vary\nslightly with layer thickness due to changes in absorption cross-section, the presence\nand position of key absorption edges and characteristic peaks, which indicate electron\ntransfer between the components, remain consistent. Therefore, the electronic\ninteraction between PNs and BS revealed by XANES is robust with respect to the\nnumberof phosphorene layers.\n44.Is the wavelength of 520nm (Figure2g(related to theexcitation wavelength in PL\nAnalysis? (electron-holeseparation efficiency)\nResponse: Thanks for the comment. The ground-state bleaching peak in\nfemtosecond transient absorption spectroscopy is not equivalent to the PL peak. In\ntransient absorption measurements, upon photoexcitation, a portion of the\nground-state carriers are promoted to the excited state. Consequently, probe light\ncorresponding to these ground-state transitions can no longer be absorbed, resulting in\na negative signal inthe transient absorption spectrum. In contrast, the PLpeak reflects\nthephotons emitted during theradiative recombination ofexcited-state electrons.\nHowever, the two characterizations are somewhat related. The femtosecond\ntransient absorption mainly captures the carrier dynamics following photoexcitation,\non a timescale from ps to ns. In contrast, PL probes the steady-state radiative\nrecombination, where the intensity primarily depends on the number of carriers\nrecombining radiatively. The connection arises because faster carrier separation\nobserved in femtosecond transient absorption reduces the probability of radiative\nrecombination, resulting in weaker PL signals, which is consistent with our PL\nmeasurements. Pleasesee page 11lines 217-220in therevised manuscript as follows:\nFurthermore, the steady-state photoluminescence (PL) results of the samples reveal a\nreduced PLintensity for 0.8PNs/BS in contrast to 0.0PNs/BS,suggesting a suppressed\ncharge carrierrecombination in 0.8PNs/BS(FigureS12c).\nFigureS12.(a)TPC,(b)EIS,(c)steady-statePL,and(d)transient-statePLresultsof0.0PNs/BS\nand0.8PNs/BS.\n45.Add asection with thistitle(Photoelectrochemical measurements)to thearticle.\nResponse: Thanks for the comment. Revised as suggested. Please see pages 7-8\ninthe revised Supporting Information as follows:\nS3.4.Electrochemical andphotoelectrochemical measurement\nTPC, EIS, and Mott-Schottky analyses were carried out employing an\nelectrochemical workstation (EC 550, Wuhan Gaoss Union Technology Co., Ltd.) in\nconjunction with a conventional three-electrode cell configuration. In this\nconfiguration, a Pt plate served as counter electrode, while aAg/AgCl (saturated KCl)\nelectrode was utilized as reference electrode. The electrolyte solution used was a 0.5\nM Na SO aqueous solution. The preparation of working electrode involved the\n2 4\nfollowing steps: Initially, an indium-tin oxide (ITO) glass was cleaned by\nultrasonication using ethanol and IPAfor 10 min each, and subsequently dried at 60℃\nin an oven. Then, 1 mg of material was dispersed in an ethanol solution (V /V\nethanol water\n= 50%), and 5 μL of Nafion was introduced. This mixture underwent ultrasonication\nfor 5 min to yield a homogeneous suspension.A10 μLaliquot of this suspension was\ndeposited onto the ITO glass substrate. Afterward, the ITO glass was heated at 80℃\nfor 30 min to ensure optimal adhesion. Following cooling to room temperature, the\nresulting product was catalyst-ITO working electrode. Illumination was provided by a\nmeasurements were carried outat room temperature.\n46. What electrolyte was used in the Electrochemical impedance spectroscopy (EIS)\nanalyses?\nResponse: Thanks for the comment. 0.5 M Na SO aqueous solution was\n2 4\nselected as the electrolyte for the EIS measurements. Please see page 7 in the revised\nSupportingInformation as follows:\nTheelectrolyte solution usedwas a0.5M Na SO aqueous solution.\n2 4\n47. What reference electrode was used in the Electrochemical impedance\nspectroscopy(EIS) analyses?\nResponse: Thanks for the comment. The EIS measurements were conducted\nusing an electrochemical workstation (EC 550, Wuhan Gaoss Union Technology Co.,\nLtd.) with a conventional three-electrode setup. In this configuration, a Pt plate was\nemployed as the counter electrode, and aAg/AgCl (saturated KCl) electrode was used\nas the reference electrode. Please see page 7 in the revised Supporting Information as\nfollows:\nTPC, EIS, and Mott-Schottky analyses were carried out employing an electrochemical\nworkstation (EC 550, Wuhan Gaoss Union Technology Co., Ltd.) in conjunction with\na conventional three-electrode cell configuration. In this configuration, a Pt plate\nserved as counter electrode, while a Ag/AgCl (saturated KCl) electrode was utilized\nas reference electrode.\n48.Check allsources again.\nResponse: Thanks for your suggestion. We have thoroughly re-checked all cited\nreferences toensure accuracy,relevance, and consistency throughout themanuscript.\n49. What is your reason for writing this sentence “Upon light illumination, this\nelectric field can drive the photo-induced electrons in the conduction band of BS to\nconsume thephoto-induced holesinthevalence bandof PNs”.\nResponse: Thanks for the comment. The reason for this statement is that it\nreflects the fundamental mechanism of the S-scheme heterojunction, which has also\nbeen documented in previous studies (Chem, 2020, 6, 1543-1559). Specifically, the\nband alignment and the resulting built-in electric field determine the migration\npathways of the photo-generated carriers. Under light irradiation, electrons in the\nconduction band of BS preferentially recombine with holes in the valence band of\nPNs at the interface. This process is driven by the internal electric field and ensures\nthe selective retention of electrons with stronger reduction potential in the conduction\nband ofPNs and holes withstronger oxidation potential inthe valence band of BS.\n50.Does p-type of PNs exist? Is BS type nor p?Pleaseuse Mott-Schottkyfor BS.\nResponse: Thanks for the comment. Regardless of the number of layers, PNs\nconsistently exhibit n-type behavior, which is also confirmed by our Mott-Schottky\nmeasurement result (Figure S13d).As for BS, it is a typical p-type semiconductor. In\np-type semiconductors, the majority carriers are holes, and the hole density near the\nvalence band is relatively low. This can lead to nonlinearity or unstable slopes in the\nMott-Schottky plot, resulting in significant uncertainty in determining the flat-band\npotential and the conduction-band position.Therefore, for p-type semiconductors, it is\nmore common to directly determine the valence-band position using VB-XPS and\nthen deduce the conduction-band position. Please see pages 12-13 lines 237-244 in\ntherevised manuscript as follows:\nFirst, the E of BS is derived from the plot of (αhν)n versus hν shown in Figure S13a,\ng\nwhere α represents absorption coefficient, h stands for Planck constant, and ν denotes\nlight frequency [32]. In this equation, n is set to 1/2 due to the indirect bandgap nature\nof BS. Consequently, the determined E value of BS stands at 1.68 eV. Subsequent to\ng\nthis, XPS valence-band spectroscopy analysis is conducted for BS. As illustrated in\nFigure S13b, the valence-band value of BS is observed to be ~1.36 V versus NHE.\nThis leads to the calculation of the conduction-band value of BS, which is found to be\n−0.32Vversus NHE (Table S1).\nFigureS13.(a)(αhν)nversushνcurveand(b)XPSvalence-bandspectrumofBS.(c)UV-vis\nabsorbancespectrumand(d)Mott-SchottkyplotofPNs(theconduction-bandvalueofPNsis\n−1.05VversusAg/AgCl,correspondingto−0.44VversusNHE).\nTableS1.E valuesandbandedgepositionsoftheheterojunctioncomponents.\ng\nComponent E value(eV) Valenceband(V) Conductionband(V)\ng\nBS 1.68 1.36 −0.32\nPNs 1.70 1.26 −0.44\n51. It is suggested that you prepare all the energy of the bandgap that you have\ncalculated using different methods in atable.\nResponse: Revised as suggested. Wehave prepared a table summarizing theband\nstructures of the heterojunction components. Please see page 34 in the revised\nSupportingInformation as follows:\nTableS1.E valuesandbandedgepositionsoftheheterojunctioncomponents.\ng\nComponent E value(eV) Valenceband(V) Conductionband(V)\ng\nBS 1.68 1.36 −0.32\nPNs 1.70 1.26 −0.44\n52.Does thetype ofBS affect planS-scheme?\nResponse: Thanks for the comment. The construction of an S-scheme\nheterojunction mainly relies on two prerequisites: (i) the two semiconductors should\npossess appropriate band structures to achieve staggered alignment, and (ii) there\nshould be a sufficiently large Fermi level difference to drive the internal electric field\nfor directional charge transfer (Chem, 2020, 6, 1543-1559). These two aspects are the\ndecisive factors for establishing an S-scheme charge transfer pathway. Whether BS is\np-type or n-type does not play the primary role. In practice, even n-n or p-p\ncombinations can form an effective S-scheme charge transfer pathway, provided the\nabove two conditions are met.Therefore, the type of BS is not the dominant factor; its\nband edge positionsandFermi level alignment with PNsare thekey determinants.\n53.In Figure 4.(a), theblue and yellow lines are thesame, howdoyou explain?\nResponse: Thanks for the comment. Although the inactivation profiles of\n0.5PNs/BS and 1.0PNs/BS in Figure 4a look quite similar, they are not strictly\nidentical. Our systematic experiments indicate that the disinfection efficiency follows\na trend of first increasing and then decreasing with PNs loading, with the optimal\nperformance observed with a PNs content of 0.8 wt%. Therefore, the similar curves\nfor 0.5PNs/BS and 1.0PNs/BS suggest that both loadings are close to, but not at, the\noptimum, resulting in comparable inactivation efficiencies. The apparent overlap in\nthe plots reflects that both loadings show similar activity near the optimal range,\nrather than meaning thetwo samples perform exactly thesame.\n54.What isthereason forthenumber 45sin Figure 4.(c)?\nResponse: Thanks for the comment. In Figure 4(c), the value of 45 s was given\nbecause 0.8PNs/BS achieved complete bacterial inactivation within this very short\ntime. In contrast, P25 TiO required up to 160 min for complete inactivation. When\n2\nplotting both datasets in the same figure, the rapid inactivation caused the decay curve\nof the faster catalyst to appear almost vertically downward. We marked 45 s because\nthe bacteria were completely inactivated within this short period for 0.8PNs/BS.\nWithout explicitly labeling this point, the precise inactivation time could not be\nclearly identified from the nearly vertical decay curve. This allows the reader to\nrecognizetheexact timescaleofcomplete bacterial inactivation.\n55.What istheconcept ofabsorption edge intheanalysis ofUV-visDRS?\nResponse: Thanks for the comment. The absorption edge in UV-vis DRS refers\nto the inflection point at which the light absorption intensity shows a steep change\nwith wavelength. This feature is commonly employed to estimate the E of\ng\nsemiconductors. We have provided a more detailed explanation. Please see page 27 in\ntherevised SupportingInformation as follows:\nAs illustrated in Figure S16c, PNs exhibit a broad absorption spanning 200-800 nm,\nwhileBS displaya characteristicsemiconductor absorption edge at approximately 682\nnm. Following the integration of BS with PNs, a subtle red shift of the absorption\nedge isobserved, suggesting theformation of aheterojunction with anarrower E .\ng\n56.Explain Electron spinresonance spectra further.\nResponse: Revised as suggested. Please see page 25 in the revised Supporting\nInformationas follows:\nElectron spin resonance spectroscopy is widely regarded as a reliable approach for\nprobing ROS. To confirm the generation of •O −, 1O , and •OH over 0.8PNs/BS, two\n2 2\nspin-trapping agents, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and\n2,2,6,6-tetramethylpiperidine (TEMP) are employed. As shown in Figure S14, only\nweak signals corresponding to DMPO-•O − 2,2,6,6-tetramethylpiperidine-N-oxyl\n2\n(TEMPO), and DMPO-•OH adducts are detected for 0.0PNs/BS, suggesting that\nlimited ROS are formed. In contrast, 0.8PNs/BS exhibits significantly stronger\nresonance features, demonstrating a substantial increase in ROS generation. Moreover,\nno detectable signal is observed under dark conditions, confirming that ROS\nproduction originates exclusively from thephotocatalytic process.\n57.Does PNs have an absorption edge in UV-visdiffusereflectance spectroscopy?\nResponse: Thanks for the comment. In principle, PNs should exhibit an\nabsorption edge. However, obtaining such data through UV-vis diffuse reflectance\nspectroscopy is challenging. This is because few-layer PNs can only be stably\nmaintained in a dispersed liquid phase. Once removed from the liquid\nenvironment—as required for UV-vis diffuse reflectance spectroscopy measurements\nin the solid state—their morphology rapidly transitions away from the few-layer state,\nleading to a significant narrowing of the band gap. As a result, the absorption edge\nfeature becomes indistinct or absent in the UV-vis diffuse reflectance spectroscopy\nresults. To address this, we performed UV-vis absorbance spectroscopy on PNs\ndispersed in liquid, which clearly shows a discernible absorption edge. Notably,\nprevious studies have also relied on absorbance spectroscopy rather than diffuse\nreflectance spectroscopy to characterize the absorption edge of PNs (Angewandte\nChemie International Edition, 2017, 56, 10373-10377). For the UV-vis absorbance\nspectroscopy result of PNs, please see page 13 lines 244-246 in the revised\nmanuscript as follows:\nFurthermore, the E of PNs is ascertained through UV-vis absorption spectroscopy\ng\nanalysis.As shown in Figure S13c, the identified absorption edge of PNs at ~731 nm\ncorresponds to an E value of1.70eV.\ng\nFigureS13.(a)(αhν)nversushνcurveand(b)XPSvalence-bandspectrumofBS.(c)UV-vis\nabsorbancespectrumand(d)Mott-SchottkyplotofPNs(theconduction-bandvalueofPNsis\n−1.05VversusAg/AgCl,correspondingto−0.44VversusNHE).\n58. What is your reason for writing this sentence “In this band alignment, PNs,\ncharacterized by a more negative conduction-band position, act as the reduction-type\ncomponent, while BS, with a more positive valence-band position, function as the\noxidation-type component”.\nResponse: Thanks for the comment. The terminology of “reduction-type\ncomponent” and “oxidation-type component” reflects the distinct energetic positions\nof the two semiconductors and the functional roles of their surviving charge carriers\nunder illumination. Specifically, PNs possess a more negative conduction-band\nposition, so the photo-excited electrons that remain in the conduction band after\ninterfacial recombination exhibit strong reduction potential. Conversely, BS have a\nmore positive valence-band position, and the photo-induced holes preserved in its\nvalence band show strong oxidation capability. This reduction–oxidation\ncomplementarity is central to the S-scheme mechanism: the internal electric field\ndrives the recombination of low-energy carriers (electrons in BS and holes in PNs),\nwhile selectively retaining the high-energy electrons in PNs and high-energy holes in\nBS. As a result, the heterostructure maximizes the utilization of the intrinsic strong\nredox potentials of the two components. The rationale for writing the sentence you\nmentioned is now directly connected to the subsequent explanation in our manuscript.\nPleasesee pages 13-14 lines 258-266 in therevised manuscript as follows:\nIn the absence of light irradiation, electrons spontaneously transfer from PNs to BS,\nestablishing an internal electric field across the heterojunction directed from PNs to\nBS. Under light irradiation, this built-in field facilitates the recombination of\nphoto-excited electrons in the conduction band of BS with photo-induced holes in the\nvalence band of PNs. Consequently, energetically favorable charge carriers are\npreserved in the conduction band of PNs and the valence band of BS. Such an\nS-scheme band alignment is anticipated to augment the ROS-production abilities of\ncharge carriers, effectively mitigating photon energy loss from a thermodynamic\nperspective.\n59.Are synthesized samples reusable (Recycling performance)? Please Perform XRD\nanalysis even after recovery (reuse).\nResponse: Thanks for the comment. We would like to emphasize an important\nconsideration regarding the evaluation of catalyst reusability. While many previous\nstudies, including some of our own prior works, relay on repeated batch experiments\nto assess material recyclability, this approach has inherent limitations. Firstly, the\nseparation of photocatalyst powders from bacterial cells or bacterial residues is\ntechnically challenging and often incomplete, which can lead to misleading\nconclusions about material stability. Secondly,during repeated use,inevitable material\nloss may occur, leading to a decrease in the actual recovery yield and affecting the\naccuracy of performance evaluation. More importantly, powdered photocatalysts are\nprimarily research tools used to elucidate fundamental mechanisms, but are not\npractical for real-world water disinfection applications. Therefore, evaluating material\nstabilitysolely based onrepeated batch recycling tests lacks practical relevance.\nTo address this, we have pioneered the incorporation of our catalyst into a\ncontinuous-flow fixed-bed reactor, enabling the direct assessment of disinfection\nperformance stability over extended operation (Advanced Materials. 2025, 37,\n2410221). In the current work, our results demonstrate that after 24 h of continuous\noperation, the disinfection efficiency remains above 99.99%, confirming the excellent\nreusability ofthecatalyst ina realisticapplication setting.\n60.Pleaseinclude kineticcurve data(Ln (C/C )=−kt ) forall analyses in thetext.\n(0.0PNs/BS, 0.1PNs/BS, 0.5PNs/BS, 0.8PNs/BS, 1.0PNs/BS, and P25 TiO ) have\n2\nbeen summarized in a single table for clarity. Please see page 36 in the revised\nSupportingInformation as follows:\nTableS3.Summaryofthekvaluesofthesamples.\nMaterial Condition kvalue(min−1)\n0.0PNs/BS Visiblelight 0.36\n0.1PNs/BS Visiblelight 0.72\n0.5PNs/BS Visiblelight 0.71\n0.8PNs/BS Visiblelight 1.30\n1.0PNs/BS Visiblelight 0.72\n0.8PNs/BS Realsunlight 9.30\nP25TiO Realsunlight 0.042\n2\n61.Do thedegradation behaviour followthefirst-order kinetics equation?\nResponse: Thanks for the comment. R2 reflects the degree of agreement between\nthe experimental data and the fitted line. Values of R2 close to 1 indicate an excellent\nfit, meaning that the experimental data can be well described by the chosen kinetic\nmodel. As indicated in the manuscript, the high R2 values (0.97 for 0.8PNs/BS and\n0.95 for P25 TiO ) confirm that the experimental data are well described by the\n2\nfirst-order kinetic model. Please see page 18 lines 349-351 in the revised manuscript\nas follows:\nThis corresponds to a first-order disinfection rate (k) of 9.30 min−1 (R2 = 0.97), which\nexceeds that of P25TiO byapproximately 221-fold (k =0.042,R2= 0.95).\nThe authors are grateful for the editor’s and reviewers’ dedicated efforts in improving\nthis paper. This manuscript has been revised to address all the issues raised by the\nreviewers. Reviewers’ suggestions are in black italic type and our responses are indent\nand in normal font. The revised text as it appears in the manuscript is in blue.\nResponses to the comments and suggestions are listed below.\nReviewer #1\nComments: The authors have provided reasonable explanations for some of my\nconcerns, which I find acceptable.\nResponse: Thanks for your positive comment. We are pleased that the current\nversion meets your expectations.\nReviewer #2\nComments: After revised, this manuscript has clarified questions and it can be\nAccepted as current form.\nResponse: Thanks for your recommendation for acceptance.\nReviewer #3\nComments: The authors of this paper investigated the Dual Optimization of Kinetic\nand Thermodynamic Constraints in Photo-induced Charge Carriers for Subminute\nPhotocatalytic Water Disinfection under Real Sunlight. In addition, the graphic\nshould be added to the main text. There are still questions that need to be answered.\nIn light of this issue and the comments described below.\nResponse: We would like to express our sincere gratitude to Reviewer #3 for the\ncontinued effort and careful reading of our revised manuscript during the second\nround of review.\nIn this round of revision, we have thoroughly addressed each of your new\ncomments. Specifically, on one hand, some of your comments pertain to\nmodifications of the manuscript itself, and we have implemented all the changes you\nsuggested (only in a few cases, mainly, where your suggestions do not fully align with\nthe editor’s guidance, we try to find a balanced solution while still doing our best to\nrespect and incorporate your suggestions). On the other hand, some comments are\nfollow-up questions regarding certain statements or expressions in our previous\nresponses. We apologize if our earlier replies are overly concise and cause any\nconfusion. In this round, we provide more detailed explanations, cite relevant\nreferences, and include related figures for your convenience.\nthe manuscript into its currently improved form. We hope that the revised version now\nmeets your expectations and that our new responses address your remaining concerns.\n1. Please write the names of the synthesized compounds in the title to be specific and\ninformative.\nResponse: Thanks for your suggestion. In response, we have included the name\nof the synthesized material in the title. The title has been determined as “2D/2D\nphosphorene/BiOI S-scheme heterojunction for subminute photocatalytic water\ndisinfection under real sunlight”. Please see the title page in the revised manuscript.\n2. This sentence in comment 8 (Bismuth oxyhalides (BiOX, X = Cl, Br, I) are a class of\nV−VI−VII ternary oxide semiconductors characterized by a layered tetragonal\nmatlockite structure, in which…) needs to be changed.\nResponse: We thank the reviewer for pointing this out. In this round of your\ncomments, Comment 15 also refers to this sentence. Your original note is “This\nsentence should be corrected in comment 15 (Bismuth oxyhalides (BiOX, X = Cl, Br, I)\nare a class of V−VI−VII ternary oxide), Because BiOX is an oxyhalide compound, not\na simple oxide.” We agree that the sentence should be corrected, as bismuth\noxyhalides should not be simply classified as an oxide. In the revised version, based\non your comment, we now describe bismuth oxyhalides as “ternary semiconductor\ncompounds”, which is also consistent with the descriptions found in the literature\n(Environ. Sci-Nano, 2014, 1: 90-112). Please see page 1 in the revised Supplementary\nInformation as follows:\nBismuth oxyhalides (BiOX, X = Cl, Br, I) are important ternary semiconductor\ncompounds [4].\nReferences for Comment 2\n[1] Ye, L. et al. Recent advances in BiOX (X = Cl, Br and I) photocatalysts: synthesis,\nmodification, facet effects and mechanisms. Environ. Sci-Nano. 1, 90-112 (2014).\n2\n3. Please change this sentence in comment 8 from (BiOX exhibit several\nadvantageous physicochemical properties…) to (BiOX compounds exhibit several\nadvantageous physicochemical properties…).\nResponse: Thanks for your suggestion. We have made the revision in accordance\nwith your instruction. Please see page 1 in the revised Supplementary Information as\nfollows:\nBiOX compounds exhibit several advantageous physicochemical properties.\n4. This sentence in comment 9, Write the phrase to produse in leading to the\nformation.\nResponse: Thanks for your suggestion. In response, we have replaced “to\nproduce” with “leading to the formation of” to make the logical relationship between\nthe redox reactions and the formation of ROS clearer. Please see page 3 lines 47-50 in\nthe revised manuscript as follows:\nGenerally, a photocatalyst with an appropriate bandgap can harness visible light to\ngenerate electron-hole pairs, which initiate redox reactions, leading to the formation\nof reactive oxygen species (ROS).\n5. Did you check the effect of pH factor?\nResponse: We sincerely appreciate your insightful comment regarding the effect\nof pH. You are correct that in our original version this aspect is not clearly indicated.\nThe redox potentials relevant to ROS formation reported in the manuscript are\nreferenced to NHE at pH 7 (Nat. Nanotechnol, 2016, 11: 1098-1104; Angew. Chem.\nInt. Ed. Engl, 2020, 59: 5218-5225). We have revised the corresponding sentence to\nmake this explicit. Please see page 3 lines 50-53 in the revised manuscript as follows:\nTheoretically, the redox potentials relevant to ROS formation are −0.33 V (O /•O −)\n2 2\nand 0.28 V (O /H O ) for electron-driven oxygen reduction, and 1.90 V (H O/•OH)\n2 2 2 2\nfor hole-driven water oxidation, all referenced to NHE at pH 7 [7, 8].\nReferences for Comment 5\n3\n[1] Liu, C. et al. Rapid water disinfection using vertically aligned MoS nanofilms and\n2\nvisible light. Nat. Nanotechnol.11, 1098-1104 (2016).\n[2] Xia, P. et al. Designing a 0D/2D S-scheme heterojunction over polymeric carbon\nnitride for visible-light photocatalytic inactivation of bacteria. Angew. Chem. Int. Ed.\nEngl. 59, 5218-5225 (2020).\n6. In line 61 of the main article, what is the pronoun their (energy losses in the\nprocesses or charge carrier transfer)?\nResponse: Thanks for pointing this out. We have noticed that the pronoun “their”\ncould be misinterpreted. So we have revised the sentence to explicitly use “these\ncarriers” when referring to ROS generation, thereby eliminating the ambiguity caused\nby the previous pronoun “their”. Please see page 3 lines 59-62 in the revised\nmanuscript as follows:\nHowever, effectively utilizing absorbed visible light for microbial inactivation\nrequires minimizing energy losses both during charge carrier transfer across the\nheterojunction interfaces and during the subsequent ROS generation by these carriers,\na limitation that current heterojunctions remain unable to overcome.\n7. Which stage does this sentence (‘the simultaneous reduction of energy…’) refer to?\nResponse: We appreciate your careful reading and valuable question. The\nsentence refers to two consecutive stages following light absorption: (1) charge carrier\ntransfer across the heterojunction interfaces, and (2) subsequent ROS generation by\nthese carriers. The ambiguity may have arisen from the use of the term “simultaneous”\n(which has now been removed), which could imply that these two processes occur at\nthe same time. To clarify this point, we have revised the text by adding “subsequent”\nto indicate their temporal sequence. In addition, the revised sentence adopts the “both\nA and B” structure to explicitly emphasize the need to reduce energy losses in both\nprocesses. We hope these revisions help eliminate any potential ambiguities and\naddress your concerns. Please see page 3 lines 59-62 in the revised manuscript as\nfollows:\nrequires minimizing energy losses both during charge carrier transfer across the\nheterojunction interfaces and during the subsequent ROS generation by these carriers,\na limitation that current heterojunctions remain unable to overcome.\n8. Please put graphical abstract in the main text.\nResponse: Thanks for your suggestion. The journal editor has informed us via\nemail with the original note stated “regarding Comments 8 and 9, graphical abstract is\nnot permitted. In your rebuttal letter, you may wish to mention to Reviewer #3 that\nthis formatting guidance was provided by the editorial office.” Accordingly, it appears\nthat graphical abstracts are not allowed in Nature Communications.\nIn response, and out of respect for your valuable input, we have redefined this\nfigure as a schematic illustration of the photocatalytic water disinfection mechanism\nrather than a graphical abstract and placed it in the revised Supplementary\nInformation. We hope this modification addresses your concern while complying with\nthe journal’s requirements. Please see page 16 lines 313-314 in the revised manuscript\nas follows:\nThe mechanism of photocatalytic water disinfection by 0.8PNs/BS is shown in Figure\nS19.\nFigure S19. Schematic illustration of 0.8PNs/BS-mediated photocatalytic water disinfection.\n9. In the graphical abstract write the full names of the compounds.\nResponse: Thanks for your suggestion. As requested, we have incorporated the\n5\nfull names of the materials into the graphical abstract. However, the journal editor has\ninformed us via email with the original note stated “regarding Comments 8 and 9,\ngraphical abstract is not permitted. In your rebuttal letter, you may wish to mention to\nReviewer #3 that this formatting guidance was provided by the editorial office.”\nAccordingly, it appears that graphical abstracts are not allowed in Nature\nCommunications.\nIn response, and out of respect for your valuable input, we have redefined this\nfigure as a schematic illustration of the photocatalytic water disinfection mechanism\nrather than a graphical abstract and placed it in the revised Supplementary\nInformation. We hope this modification addresses your concern while complying with\nthe journal’s requirements. Please see page 30 in the revised Supplementary\nInformation as follows:\nFigure S19. Schematic illustration of 0.8PNs/BS-mediated photocatalytic water disinfection.\n10. Please explain this sentence (the formation of ROS is thermodynamically limited,\nleading to energy loss.) further in response to comment 12. Is real energy wasted or is\nit thermodynamically impossible?\nResponse: Thanks for your comment. The sentence you referred to originates\nfrom our previous response: “If the conduction band minimum or valence band\nmaximum of the photocatalyst does not possess sufficient potential to drive the\ndesired redox reactions, the formation of ROS is thermodynamically limited, leading\nto energy loss.” We understand that the phrase “thermodynamically limited” may\nappear ambiguous without further clarification. To address your concern, we would\n6\nlike to further clarify this point in more detail. We would like to cite a sentence from a\nclassic reference (Chem, 2020, 6: 1543-1559), as its explanation is more intuitive and\neasier to understand: [Redacted]. Please note that the “Figures 2B and 2C” mentioned\nin this paragraph corresponds to Figure R1 shown below.\n[Figure Redacted]\nFigure R1. A ball collided by another ball from (B) a high and (C) a low altitude.\nIn more detail, for example, in the case of O reduction to H O , the\n2 2 2\nthermodynamic driving force of this reaction depends on the difference between the\nconduction-band potential of a semiconductor and the redox potential of this reaction\n(O /H O , 0.28 V versus NHE). For instance, one semiconductor with a\n2 2 2\nconduction-band potential of 0.26 V versus NHE provides a stronger thermodynamic\ndriving force for this reaction than another semiconductor with a conduction-band\npotential of 0.27 V versus NHE. Conversely, if a semiconductor exhibits a\nconduction-band potential (e.g., 0.29 V versus NHE) that is less negative than the\nredox potential of the reaction (0.28 V versus NHE), the photo-generated electrons\nwould not have sufficient thermodynamic driving force to initiate this reduction\nreaction (in analogy to the example of the ball collision above, this situation is like\nwhen the red ball lies to the right of the green ball—it cannot strike the green ball to\nlift it to any height on the right). In this case, the photo-generated electrons excited by\nlight energy cannot produce H O . Their eventual fate is well-known: they recombine\n2 2\nwith photo-generated holes, releasing the absorbed solar energy as heat (ACS. Omega,\n7\n2020, 5: 31644-31656). This portion of energy is therefore wasted due to the absence\nof H O formation, which is what we mean by “the formation of ROS is\n2 2\nthermodynamically limited, leading to energy loss.” We hope this detailed explanation\nresolves your query.\nReferences for Comment 10\n[1] Teng, Z. et al. Edge-functionalized g-C N nanosheets as a highly efficient\n3 4\nmetal-free photocatalyst for safe drinking water. Chem.5, 664-680 (2019).\n[2] Hendi, A. H. et al. Visible light-driven photoelectrocatalytic water splitting using\nZ-scheme Ag-decorated MoS /RGO/NiWO heterostructure. ACS. Omega. 5,\n2 4\n31644-31656 (2020).\n11. Please provide 13 references for comment.\nResponse: We thank the reviewer for the comment. In our previous response to\nyour Comment 13, the modification we made lacks literature support. We have now\nincluded an appropriate reference (Chem. Commun, 2014, 50: 10768-10777). The\noriginal text from this work states: “In comparison with other 2D material based\ncomposites (i.e., 0D-2D and 1D-2D composites), a solid construction can be achieved\nby the 2D-2D layered composites due to the large contact surface between the sheets.\nMoreover, the large contact area of the 2D layered composite should lead to more\nefficient interfacial charge transfer.” We believe this statement strongly supports our\npoint. Please see page 4 lines 76-79 in the revised manuscript as follows:\nOn one hand, both PNs and BS possess a 2D nanostructure, enabling them to form\nintimate “face to face” contacts with robust interfacial interactions for fast charge\ncarrier transfer (2D/2D heterojunctions provide larger interfacial contact areas than\nother counterparts, e.g., 0D/2D or 1D/2D) [19].\n[19] Low, J., Cao, S., Yu, J., Wageh, S. Two-dimensional layered composite\nphotocatalysts. Chem. Commun. 50, 10768-10777 (2014).\n12. In comment 13, use the phrase on the other hand, instead of on one hand.\nComment 13, we have taken into account not only the revised sentence itself, but also\nits context within the surrounding text. Specifically, the sentence we revised is\nfollowed by a sentence beginning with “On the other hand...” In this context,\nbeginning our revised sentence with “On one hand...” is appropriate. Together, the\ntwo sentences clearly convey the different aspects intended by the “On one hand…\nOn the other hand…” construction. For your convenience, we have provided these\ntwo consecutive sentences below (they appear on page 4 lines 76-81 in the revised\nmanuscript):\nOn one hand, both PNs and BS possess a 2D nanostructure, enabling them to form\nintimate “face to face” contacts with robust interfacial interactions for fast charge\ncarrier transfer (2D/2D heterojunctions provide larger interfacial contact areas than\nother counterparts, e.g., 0D/2D or 1D/2D) [19]. On the other hand, a well-defined\nS-scheme band alignment results in the accumulation of electrons and holes with\nenhanced redox abilities for elevated ROS generation.\n13. In comment 14, does the photocatalytic process of adsorption and desorption\noccur on the surface of the photocatalyst in the dark phase?\nResponse: We thank the reviewer for raising this important question. In our\nprevious response, we may not have fully understood your concern. It appears that\nyou are asking whether adsorption and desorption of bacteria occur on the surface of\nthe photocatalyst in the dark.\nIn fact, you may also have noticed that, in studies on photocatalytic organic\npollutant degradation, the adsorption-desorption behavior of organic molecule on the\nphotocatalyst surface is an essential aspect that is systematically examined in almost\nall relevant literature (Appl. Catal. B-Environ, 2015, 176-177: 240-248). Researchers\nin this field, including our group, routinely investigate how organic molecules interact\nwith the catalyst surfaces through such adsorption-desorption processes.\nHowever, for photocatalytic bacterial inactivation, based on our research\nexperience and a thorough review of the literature, there is currently no research\n9\nframework analogous to “adsorption-desorption” applied to bacteria (Adv. Mater,\n2024, 37: 2410221; Nat. Nanotechnol, 2016, 11: 1098-1104; Nat. Water, 2023, 1:\n462-470). This is because adsorption refers to the accumulation of “molecules or ions”\nfrom gases or liquids on a solid surface, and bacteria, being much larger than such\nmolecules or ions, cannot be regarded as adsorption targets. To clarify, we directly\nquote the original text from an authoritative textbook (Environmental Organic\nChemistry, John Wiley & Sons: New York, 2002, p 277):\n[Redacted]\nBacteria are µm-sized living entities, as shown in Figure R2 below (Environ. Sci.\nTechnol, 2018, 52: 4774-4784). They are even much larger than the nm-sized\nphotocatalysts we prepare. Therefore, bacteria do not fall under the definition of\nmolecules or ions for adsorption. In summary, to the best of our knowledge, a\nresearch framework analogous to “adsorption-desorption” has not been applied to\nbacteria in previous studies related to photocatalytic water disinfection, and\naccordingly, it is not employed in our present work either (Adv. Mater, 2024, 37:\n2410221; Nat. Nanotechnol, 2016, 11: 1098-1104; Nat. Water, 2023, 1: 462-470).\n[Figure Redacted]\nFigure R2. SEM image of bacteria, highlighting that they are µm-sized living entities (scale bar:\n2\nµm).\nReferences for Comment 13\n[1] Liang, R. et al. A simple strategy for fabrication of Pd@MIL-100(Fe)\nnanocomposite as a visible-light-driven photocatalyst for the treatment of\n10\npharmaceuticals and personal care products (PPCPs). Appl. Catal. B-Environ.\n176-177, 240-248 (2015).\n[2] Yang, H. et al. Visible‐light‐induced rapid elimination of antibiotic resistance\ncontaminations using graphitic carbon nitride tailored with carrier confinement\ndomains. Adv. Mater. 37, 2410221 (2024).\n[3] Liu, C. et al. Rapid water disinfection using vertically aligned MoS nanofilms and\n2\nvisible light. Nat. Nanotechnol.11, 1098-1104 (2016).\n[4] Wu, T. et al. Solar-driven efficient heterogeneous subminute water disinfection\nnanosystem assembled with fingerprint MoS . Nat. Water.1, 462-470 (2023).\n2\n[5] Schwarzenbach, R. P. et al. Environmental Organic Chemistry, John Wiley &\nSons: New York, p 277 (2002).\n[6] Wang, T. et al. Enhanced visible-light-driven photocatalytic bacterial inactivation\nby ultrathin carbon-coated magnetic cobalt ferrite nanoparticles. Environ. Sci. Technol.\n52, 4774-4784 (2018).\n14. How does the internal electric field cause efficient electron and hole separation?\nResponse: We thank the reviewer for this valuable comment. To carefully explain\nhow the internal electric field causes efficient electron-hole separation, we have\nselected a schematic illustration from a key literature (Nat. Commun, 2024, 15: 4807),\nas shown below:\n[Figure Redacted]\nFigure R3. Schematic illustration of the charge transfer mechanism in an S-type heterojunction.\nIn this figure, the band structure of a typical S-scheme heterojunction is depicted.\nThe light blue arrow indicates the direction of the internal electric field. The electric\nfield points from the positively charged region to the negatively charged region.\nUnder this field, electrons (negatively charged) experience a force opposite to the\n11\nfield direction, while holes (positively charged) are driven along the field direction.\nAs a result, the electric field facilitates the recombination of photo-excited electrons\nin the conduction band of the left-hand component with photo-induced holes in the\nvalence band of the right-hand component. As a result, photo-generated charge\ncarriers with strong redox capabilities in the conduction band of the right-hand\ncomponent and the valence band of the left-hand component are preserved, thereby\nenabling the so-called “efficient electron and hole separation.” This mechanism is\nconsistent with previously reported studies (Angew. Chem. Int. Ed. Engl, 2020, 59:\n5218-5225; Chem, 2020, 6: 1543-1559). We hope this explanation addresses your\nquestion.\nReferences for Comment 14\n[1] Deng, X. et al. Ultrafast electron transfer at the In O /Nb O S-scheme interface\n2 3 2 5\nfor CO photoreduction. Nat. Commun.15, 4807 (2024).\n2\n[2] Xia, P. et al. Designing a 0D/2D S-scheme heterojunction over polymeric carbon\nnitride for visible-light photocatalytic inactivation of bacteria. Angew. Chem. Int. Ed.\nEngl. 59, 5218-5225 (2020).\n[3] Xu, Q. et al. S-scheme heterojunction photocatalyst. Chem.6, 1543-1559 (2020).\n15. This sentence should be corrected in comment 15 (Bismuth oxyhalides (BiOX, X =\nCl, Br, I) are a class of V−VI−VII ternary oxide), Because BiOX is an oxyhalide\ncompound, not a simple oxide.\nResponse: Thanks for pointing this out. We agree that the sentence should be\ncorrected, as bismuth oxyhalides should not be simply classified as an oxide. In the\nrevised version, based on your comment, we now describe bismuth oxyhalides as\n“ternary semiconductor compounds”, which is also consistent with the descriptions\nfound in the literature (Environ. Sci-Nano, 2014, 1: 90-112). Please see page 1 in the\nrevised Supplementary Information as follows:\nBismuth oxyhalides (BiOX, X = Cl, Br, I) are important ternary semiconductor\ncompounds [4].\n1. Ye, L. et al. Recent advances in BiOX (X = Cl, Br and I) photocatalysts: synthesis,\nmodification, facet effects and mechanisms. Environ. Sci-Nano. 1, 90-112 (2014).\n16. Check reference 2 again in comment 18.\nResponse: We appreciate the reviewer’s reminder. The section in the\nSupplementary Information citing Reference 2 (Adv. Mater, 2018, 30: 1800128) reads\nas follows: “PNs, known as the few-layer form of BP, have recently garnered\nsignificant attention owing to the unique physicochemical properties: (i) a high\nsurface-to-volume ratio with abundant accessible active sites; (ii) a distinctive\nlayer-dependent direct bandgap, coupled with tunable redox properties of charge\ncarriers; (iii) a broad light absorption capacity across the entire visible-light region [2].\nBenefiting from these characteristics, PNs have been explored in diverse\nphotocatalytic applications, including water splitting, pollutant degradation, and H O\n2 2\nproduction [2, 3].”\nWe have carefully re-examined Reference 2, which states that “Recently,\nmetal-free phosphorene has attracted tremendous attention as an emerging 2D\nmaterial due to its unique features of i) thickness dependent band gap ranging from\n0.3 to 2.0 eV,[14,50-56] ii) high charge mobility of ≈ 1000 cm2 V−1 s−1 ,[51,53,56] and iii)\nlarge specific surface area with high ratio of exposed surface atoms. [14,53,56]” In\naddition, Reference 2 investigates the optical absorption properties of the materials by\nUV-vis diffuse reflectance spectroscopy and reports that “an increased light\nabsorption in the range of ≈ 460-800 nm is ascribed to the presence of phosphorene.”\nThus, the content of Reference 2 aligns well with our corresponding statements in the\nSupplementary Information: “PNs, known as the few-layer form of BP, have recently\ngarnered significant attention owing to the unique physicochemical properties: (i) a\nhigh surface-to-volume ratio with abundant accessible active sites; (ii) a distinctive\nlayer-dependent direct bandgap, coupled with tunable redox properties of charge\ncarriers; (iii) a broad light absorption capacity across the entire visible-light region\n13\n[2].”\nMoreover, Reference 2 reports on photocatalytic water splitting, which supports\nthe subsequent sentence in Supplementary Information mentioning “Benefiting from\nthese characteristics, PNs have been explored in diverse photocatalytic applications,\nincluding water splitting, pollutant degradation, and H O production [2, 3].”\n2 2\nTherefore, we believe that the citation of Reference 2 in this context is\nappropriate. We hope this clarification resolves your concern.\nReferences for Comment 16\n[1] Ran, J. et al. Metal-free 2D/2D phosphorene/g-C N Van der Waals heterojunction\n3 4\nfor highly enhanced visible-light photocatalytic H production. Adv. Mater. 30,\n2\n1800128 (2018).\n17. In comment 18, the expression (result, can offer a rough estimation for the\nconduction-band value) is used, which is a limited and imprecise value. Please check.\nResponse: We appreciate the reviewer’s reminder. We would like to clarify that\nthe expression “rough estimation” does not imply any inaccuracy or unreliability of\nour results. In fact, it follows the conventional terminology used in Mott-Schottky\nanalysis. For n-type semiconductors, the Mott-Schottky test determines the flat-band\npotential instead of directly measuring the conduction-band minimum. Therefore,\ndescribing it as a “rough estimation” accurately reflects the methodological nature of\nthis approach rather than any imprecision in the data itself. In fact, such phrasing is\nwidely adopted in authoritative literature, such as Nat. Commun, 2019, 10: 2177,\nwhere it is stated that “The Mott-Schottky measurements conducted at three different\nfrequencies give the n-type semiconductor nature of ZIF-8 and the flat band position\nof ZIF-8 at ~−1.2V vs. NHE, which roughly equals to the bottom of conduction band\n(Supplementary Fig. 11).” As can be seen, this article also uses similar wording\n“roughly equals.” Avoiding such phrasing would actually make the description less\naccurate.\nTo ensure the reliability of our result, we further compare the obtained\n14\nconduction-band value with reported data for phosphorene. The conduction-band\nposition determined in our work (−0.44 V versus NHE) is in close agreement with that\nreported in literature (Adv. Mater, 2018, 30: 1800128; −0.40 V versus NHE).\nTherefore, although the term “rough estimation” is employed to reflect the\nmethodological convention of Mott-Schottky analysis, the derived conduction-band\nposition is scientifically reasonable and consistent with literature value.\nReferences for Comment 16\n[1] Li, P. et al. Metal-organic frameworks with photocatalytic bactericidal activity for\nintegrated air cleaning. Nat. Commun.10, 2177 (2019).\n[2] Ran, J. et al. Metal-free 2D/2D phosphorene/g-C N Van der Waals heterojunction\n3 4\nfor highly enhanced visible-light photocatalytic H production. Adv. Mater. 30,\n2\n1800128 (2018).\n18. In comment 19, sentence (our study aims to demonstrate that optimizing the\ncompatibility between the macroscopic geometric structures), which parameter is it?\nLayer dimensions or number of layers or...\nResponse: We appreciate the reviewer’s question. In our study, the term\n“macroscopic geometric structure” describes the overall geometrical configuration of\nthe heterojunction components (e.g., 0D, 2D, or 3D). In this context, both PNs and\nBiOX belong to the 2D category, and therefore, their geometric structures exhibit\ncompatibility. This concept, in fact, is explained in the Introduction section of the\nmain text, which is refined under your guidance in the first round revision. Please see\npage 4 lines 76-79 in the revised manuscript as follows:\nOn one hand, both PNs and BS possess a 2D nanostructure, enabling them to form\nintimate “face to face” contacts with robust interfacial interactions for fast charge\ncarrier transfer (2D/2D heterojunctions provide larger interfacial contact areas than\nother counterparts, e.g., 0D/2D or 1D/2D) [19].\n19. In comment 20, what do you mean by bismuth being layered? Which factor plays a\n15\nmore important role? Layer thickness or number of layers or layer spacing or.....\nResponse: Thanks for the comment. We have located our response to your\noriginal Comment 20, in which the term “layered BiOI” is used, which may have\ncaused some confusion. In short, in our previous reply, the term “layered BiOI” is\nused solely to describe the 2D morphology of BiOI (its nanosheet-like structure), and\nis by no means intended to refer to properties like the number of layers. Below, we\nprovide a detailed explanation of why this term is used.\nIn your original comment, you ask, “Does the layered structure of bismuth\ncompounds contribute to their photocatalytic activity?” In our original response to this\ncomment, we use the term “layered BiOI” just to match the wording you used, so it\nwould be easier to follow. In fact, this “layered BiOI” is exactly the same material as\nthe BiOI nanosheets (BS) mentioned in the main text. In the literature, the term\n“layered XXX” is commonly used to describe 2D morphologies, such as\nnanosheet-like or nanoflake-like structures, which accurately reflect the layered nature\nof the 2D materials. For instance, for the well-known 2D material g-C N , some\n3 4\nstudies refer to it as “g-C N nanosheets” (J. Am. Chem. Soc, 2017, 139: 13234-13242)\n3 4\nwhile others describe it as “layered g-C N ” (Adv. Funct. Mater, 2018, 28: 1800668).\n3 4\nThis illustrates that both terminologies are commonly accepted to denote the same\nstructural feature. We hope this clears up any confusion regarding the terminology.\nReferences for Comment 19\n[1] Zhu, M. et al. Metal-free photocatalyst for H evolution in visible to near-infrared\n2\nregion: black phosphorus/graphitic carbon nitride. J. Am. Chem. Soc. 139,\n13234-13242 (2017).\n[2] Kong, L. et al. g-C N loading black phosphorus quantum dot for efficient and\n3 4\nstable photocatalytic H generation under visible light. Adv. Funct. Mater. 28,\n2\n1800668 (2018).\n20. In comment 21, the word anticipated is used. Does this mean that it has not been\nproven yet?\n“anticipated” is simply used to introduce the following content. The sentence is\nstructured as “XXXX is anticipated” followed by “To confirm this, XXXX”,\nindicating that the anticipation is immediately addressed and verified in the\nsubsequent text. Below, we provide a detailed explanation.\nIn the context of the original sentence: “The observed “face to face” contact\nbetween the two 2D components, PNs and BS, within the constructed heterojunction,\nis anticipated to create a strong interfacial interaction between the layers.”, the term\n“anticipated” indeed indicates that the strong interfacial interaction has not yet been\ndirectly proven at that point in the text. This sentence serves primarily as a transition\nto introduce the subsequent text: “To confirm this, synchrotron-based X-ray\nabsorption near-edge structure (XANES) analysis is employed.” Reading these two\nsentences together clarifies that the anticipated interaction is immediately followed by\nexperimental verification, providing both logical flow and supporting evidence. We\nhope this clarification resolves your concern.\n21. The reference in comment 24 is not valid. Please replace it.\nResponse: We apologize for the inconvenience caused in the first-round response,\nwhere all references cited in our comments are given in abbreviated form, which may\nhave made it difficult for you to assess their validity. We understand that the reviewer\nmay have concerns regarding the citation format or completeness. We also note that,\na similar issue is raised by you in Comment 31 of the current round. To address these,\nin the current round, all references cited in our responses are provided in full\nimmediately following each corresponding comment, including authors, title,\njournal, year, volume, and page numbers. We hope this practice resolves your concern.\nNow, the reference in our original Comment 24 corresponds to the following\npassage in page 20 lines 387-390 in the revised manuscript (we reference this work\nbecause our procedure for removing the oxide layers of red phosphorus follows the\nmethod described therein): “In a standard experimental setup, commercial red\nphosphorus (2 g) was dispersed in 15 mL of H O and hydrothermally treated at 200°C\n2\n17\nfor 12 h to remove surface oxide layers, and then dried in an oven [9].”\n[9] Xia, D., Shen, Z., Huang, G., Wang, W., Yu, J. C., Wong, P. K. Red phosphorus: an\nEarth-abundant elemental photocatalyst for “green” bacterial inactivation under\nvisible light. Environ. Sci. Technol. 49, 6264-6273 (2015).\n22. Comment 24: You wrote that you did not complete the step. How was the oxide\nlayer removed?\nResponse: We thank the reviewer for the comment. We realize that in our\nfirst-round response, we may have misunderstood your question. It seems that you are\nasking whether the oxide layers on red phosphorus are removed using the\nhydrothermal method. The current version now explicitly states that the commercial\nred phosphorus is indeed treated hydrothermally to remove surface oxide layers. This\nprocedure ensures the removal of surface oxide layers prior to subsequent\nexperiments. Please see page 20 lines 387-390 in the revised manuscript as follows:\nIn a standard experimental setup, commercial red phosphorus (2 g) was dispersed in\n15 mL of H O and hydrothermally treated at 200°C for 12 h to remove surface oxide\n2\nlayers, and then dried in an oven [9].\n23. In comment 26, you wrote sentence (the overall morphology of BP does not\nfundamentally change). Please write more precisely.\nResponse: Thanks for the comment. In your original Comment 26, you inquire\nwhether the calcination temperature would affect the morphology of BP. Our response\nis “As long as the temperature is sufficient to enable complete sublimation of red\nphosphorus and interaction with the mineralizer, the overall morphology of BP does\nnot fundamentally change.” This sentence may appear somewhat general. Here, we\nwould like to clarify it more precisely.\nFor example, in a previous study (Cryst. Growth. Des, 2016, 16: 1096-1103), the\nsynthesis of BP is conducted by heating red phosphorus, tin, and iodine from room\ntemperature to 863 K (589.85°C) and maintaining this temperature for 2 h, followed\n18\nby cooling to 758 K (484.85°C) for 2 h, and then to 393 K (119.85°C). The resulting\nBP exhibits a typical 2D layered morphology, as shown below:\n[Figure Redacted]\nFigure R4. SEM images of BP in the literature.\nIn contrast, in our work, the synthesis of BP is carried out by heating red\nphosphorus, tin, and iodine to 600°C, holding for 2 h, then cooling to 490°C and\nmaintaining for 2 h, followed by gradual cooling to 120°C. The obtained BP also\nshows a 2D layered morphology, as shown below:\nFigure S6. SEM images of BP.\nClearly, although the calcination temperature differ between the literature and\nour experiment, both prepared BP materials show a 2D morphology. Therefore, what\nwe intended to convey is that within the temperature range sufficient to ensure\ncomplete sublimation of red phosphorus and effective mineralizer-assisted growth,\nvariations in calcination temperature does not significantly alter the 2D morphology\nof BP. To make this statement more precise, the original sentence can be revised to\n“As long as the temperature is sufficient to ensure complete sublimation of red\nphosphorus and its interaction with the mineralizer, BP maintains its characteristic 2D\n19\nlayered morphology.” We hope that this clarification addresses your concern.\nReferences for Comment 23\n[1] Zhao, M. et al. Growth mechanism and enhanced yield of black phosphorus\nmicroribbons. Cryst. Growth. Des.16, 1096-1103 (2016).\n24. Please provide 27 references for comment.\nResponse: We thank the reviewer for the comment. In response to your original\nComment 27, two relevant references are cited. Please see pages 3-4 in the revised\nSupplementary Information as follows:\nLiquid exfoliation process generally involves dispersing bulk materials in a selected\nexfoliating medium and utilizing the energy from ultrasonication to disrupt the Van\nder Waals force between the layers of bulk materials, thus obtaining few-layer 2D\nmaterials. This method does not require harsh chemical treatments or high\ntemperatures, is broadly applicable to various 2D materials, and can potentially be\nscaled up, making it widely adopted [8, 9]. During the exfoliation process, the\nchoice of exfoliating medium plays a crucial role in determining the quality of\nproduct.\nTheoretically, achieving efficient exfoliation is contingent on matching the surface\nenergy of solvent with that of material. This condition minimizes the enthalpy of the\nmixed system, as described by the equation of ΔH /V ≈ 2(δ − δ )2φ/T , where\nmix mix G sol bulk\nΔH, V ,δ, φ, and T represent the enthalpy of mixing, the volume of dispersion,\nmix bulk\nthe square root of component surface energy, the volume fraction of nanosheet, and\nthe average thickness of nanosheet, respectively [8, 9].\n[8] Hernandez, Y. et al. High-yield production of graphene by liquid-phase exfoliation\nof graphite. Nat. Nanotechnol.3, 563-568 (2008).\n[9] Coleman, J. N. et al. Two-dimensional nanosheets produced by liquid exfoliation\nof layered materials. Science.331, 568-571 (2011).\n25. Write other (advantage of the method ultrasonic exfoliation process) in response\n20\nto comment 28.\nResponse: We thank the reviewer for the comment. Regarding the ultrasonic\nexfoliation process mentioned in original Comment 28, we have carefully revisited\nthe two classic references cited in the Supplementary Information (Nat. Nanotechnol,\n2008, 3: 563-568; Science, 2011, 331: 568-571). From these studies, we extract\nseveral advantages of the ultrasonic exfoliation method, including: (i) it does not\nrequire harsh chemical treatments or high temperatures, (ii) it can potentially be\nscaled up, (iii) it is broadly applicable to various layered materials, (iv) it allows\nrelatively simple and rapid preparation. Based on these points, we have revised our\noriginal description to better reflect the advantages of ultrasonic exfoliation. Please\nsee page 3 in the revised Supplementary Information as follows:\nThis method does not require harsh chemical treatments or high temperatures, is\nbroadly applicable to various 2D materials, and can potentially be scaled up, making\nit widely adopted [8, 9].\nReferences for Comment 25\n[1] Hernandez, Y. et al. High-yield production of graphene by liquid-phase exfoliation\nof graphite. Nat. Nanotechnol.3, 563-568 (2008).\n[2] Coleman, J. N. et al. Two-dimensional nanosheets produced by liquid exfoliation\nof layered materials. Science.331, 568-571 (2011).\n26. Please provide 28 references for comment.\nResponse: Thanks for the comment. Revised as suggested. Please see page 3 in\nthe revised Supplementary Information as follows:\nThis method does not require harsh chemical treatments or high temperatures, is\nbroadly applicable to various 2D materials, and can potentially be scaled up, making\nit widely adopted [8, 9].\n[8] Hernandez, Y. et al. High-yield production of graphene by liquid-phase exfoliation\nof graphite. Nat. Nanotechnol.3, 563-568 (2008).\n21\n[9] Coleman, J. N. et al. Two-dimensional nanosheets produced by liquid exfoliation\nof layered materials. Science.331, 568-571 (2011).\n27. In comment 33, do other parameters such as solvent viscosity and polarity also\nhave an effect?\nResponse: We appreciate the reviewer’s comment. Indeed, other solvent\nparameters can also influence the exfoliation process. Taking polarity, as you\nmentioned, as an example, it can affect the interactions between 2D materials and\nexfoliating mediums. As described in Science, 2011, 331: 568-571, the Hansen\nsolubility parameters provide an approach to quantify how exfoliating medium\ninfluences the exfoliation process. These parameters incorporate three contributions to\nthe cohesive energy density: dispersion, polar, and hydrogen-bonding interactions. In\npractice, effective exfoliation of a specific 2D material can only be achieved when all\nthree parameters (dispersion, polar, and hydrogen bond) of the solvent closely match\nthose of the 2D material. As can be seen, polarity is not an independent parameter,\nrather, it is inherently embedded within the Hansen parameter set. That is to say,\nalthough polarity is one of the parameters influencing exfoliation, its effect cannot be\nclearly isolated from other intermolecular interactions, making it methodologically\nchallenging to use polarity as an independent screening criterion. In other words,\nwhile polarity does play a role, it is not appropriate to treat it as a standalone indicator\nfor solvent selection.\nIn contrast, the surface energy is an independent parameter that has been widely\nand successfully used for initial solvent selection. Although other parameters may\ninfluence the exfoliation process, their existence does not undermine the validity of\nusing surface energy as a reliable descriptor, which is well supported by the\nexperimental results in this work. Also, many classical studies have employed surface\nenergy as a guiding parameter to identify suitable exfoliating mediums for various 2D\nmaterials (J. Am. Chem. Soc, 2013, 135: 18-21; ACS Nano, 2016, 10: 2745-2751; Nat.\nNanotechnol, 2008, 3: 563-568). We hope that this clarification addresses your\nconcern.\n[1] Coleman, J. N. et al. Two-dimensional nanosheets produced by liquid exfoliation\nof layered materials. Science.331, 568-571 (2011).\n[2] Zhang, X. et al. Enhanced photoresponsive ultrathin graphitic-phase C N\n3 4\nnanosheets for bioimaging. J. Am. Chem. Soc. 135, 18-21 (2013).\n[3] Han, Q. et al. Atomically thin mesoporous nanomesh of graphitic C N for\n3 4\nhigh-efficiency photocatalytic hydrogen evolution. ACS Nano. 10, 2745-2751 (2016).\n[4] Hernandez, Y. et al. High-yield production of graphene by liquid-phase exfoliation\nof graphite. Nat. Nanotechnol.3, 563-568 (2008).\n28. In comment 42, Explain accumulation of lines further. What does it represent?\nResponse: We appreciate the reviewer’s comment. In our previous response, we\nmay have provided an overly brief explanation. In this round, we offer a more detailed\nclarification regarding your question: “Explain accumulation of lines further. What\ndoes it represent?” In short: “Each curve in Figures 2e and f represents the absorption\nchange between the excited and ground states of the material (0.0PNs/BS or\n0.8PNs/BS) at a specific delay time (0.5, 1, 5, 10 ps......), and plotting multiple curves\non one figure simply visualizes the spectral evolution over time without implying any\n“accumulation” of the signal. A more detailed explanation is provided below.\nFor semiconductor heterojunctions, the key photophysical processes following\nlight excitation include excited-state absorption, ground-state bleaching, and\nstimulated emission. It is worth noting that while all these processes can occur, they\nevolve on different time scales. To facilitate understanding, we give an example: upon\nlight excitation, a molecule can undergo numerous distinct photophysical processes\n(such as fluorescence, phosphorescence, internal conversion, and so on), as depicted\nin the following schematic:\n23\n[Figure Redacted]\nAll these processes may take place within a photo-excited system, but their\ncharacteristic lifetimes differ by several orders of magnitude, ranging from fs-s, as\nshown below:\n[Figure Redacted]\nSimilarly, after light excitation, in semiconductor heterojunctions, processes such\nas excited-state absorption, ground-state bleaching, and stimulated emission also take\nplace on different time scales. To investigate these ultrafast photophysical processes,\nfemtosecond transient absorption spectroscopy, conducted in our study, is a\npowerful technique, as it allows direct tracking of the dynamic evolution of\nthese processes. The configuration of a femtosecond transient absorption\nspectrometer is illustrated as follows:\n[Figure Redacted]\nIn the above figure, the light emitted from the green instrument is used to excite\nthe sample, and after a very short delay (0.5, 1, 5, 10 ps......), a probe beam (from the\nblue instrument) monitors the changes in the sample’s absorption. Femtosecond\ntransient absorption spectroscopy can be understood as an “ultrafast version” of\nUV-vis absorption spectroscopy, recording the evolution of the sample’s absorption\nover time with femtosecond time resolution. However, when directly comparing\nabsorption spectra at, for example, 0.0 ps and 0.5 ps, it is difficult to visually discern\nsignificant differences, as the changes are typically very small. To facilitate\nobservation, the data in femtosecond transient absorption spectroscopy are plotted\nusing ΔA on the vertical axis, where ΔA = A − A , representing the difference\nexcited ground\nbetween the excited-state and ground-state absorption. The sign of ΔA can be used to\nidentify which photophysical process dominates at a given timescale. For instance,\nwhen ΔA < 0, this indicates the occurrence of ground-state bleaching. This is because\nthat, before excitation, most electrons in the semiconductor material reside in the\nground state. Upon light excitation, some of these electrons are promoted to the\nexcited state, reducing the population of ground-state electrons—that is, fewer\nelectrons are available to absorb the probe beam (from the blue instrument). As a\nresult, the measured absorption signal decreases, manifesting as a negative ΔA.\nIn summary, based on the detailed explanation above, we hope it is now clear\nwhat the curves in Figures 2e and f represent: each curve corresponds to the\nabsorption change between the excited-state and ground-state sample (0.0PNs/BS or\n0.8PNs/BS) at a specific delay time (0.5, 1, 5, 10 ps......). Plotting the curves measured\nat different delay times on one figure is simply a way to visually illustrate the spectral\nevolution over time (0.5, 1, 5, 10 ps......), and does not imply any “accumulation” of\nthe signal. We hope this explanation makes it clear.\n29. In comment 43, Sentence (The number of layers of PNs in the heterostructure is\nnot expected to significantly affect the qualitative…), do you have real data or are you\njust expecting it?\nResponse: Thanks for the comment. To be honest, our previous response is based\non a comprehensive review of relevant literature rather than on direct experimental\ndata from our current work. In practice, it is nearly impossible to precisely obtain or\n25\nisolate a dispersion containing phosphorene nanosheets with a single, fixed number of\nlayers. Liquid exfoliation typically produces phosphorene nanosheets within a certain\nlayer-number range, rather than nanosheets with a specific number of layers.\nFor instance, a representative literature (J. Am. Chem. Soc, 2017, 139: 13234-13242)\nstates : “Figure S1 shows the thickness of as-exfoliated BP nanoflakes ranging from\n1.8 to 5.1 nm, which are close to that of the 3~8 phosphorus atomic layers according\nto the monolayer thickness of 0.5-0.7 nm.” Also, Angew. Chem. Int. Ed, 2017, 56:\n10373-10377 reports: “A one-step liquid exfoliation approach followed by\nhigh-speed centrifugation was used to prepare BP nanosheet (BPS, 8-11 nm in\nthickness, 10-14 layers) and FPS (4-5 nm in thickness, 5-6 layers) as confirmed in\nFigures S3a-d and S4a-d, respectively.”\nTherefore, since the exfoliated samples inherently contain phosphorene\nnanosheets with a distribution of layer numbers, it is experimentally unfeasible, with\ncurrent scientific techniques, to systematically investigate the effect of the exact layer\nnumber of phosphorene nanosheets on the experimental results. We hope this\nclarification meets your expectations.\nReferences for Comment 29\n[1] Zhu, M. et al. Metal-free photocatalyst for H evolution in visible to near-infrared\n2\nregion: black phosphorus/graphitic carbon nitride. J. Am. Chem. Soc. 139,\n13234-13242 (2017).\n[2] Ran, J. et al. Phosphorene co-catalyst advancing highly efficient visible-light\nphotocatalytic hydrogen production. Angew. Chem. Int. Ed. 56, 10373-10377 (2017).\n30. In comment 44, Why aren’t curves EIS arc-shaped?\nResponse: Thanks for the comment. We apologize as this is our oversight, and a\nmore detailed description of the experimental procedure may have prevented this\nconcern. We clarify that the EIS measurements reported in our work are performed\nunder dark conditions. In the dark, no photo-generated carriers are present.\nConsequently, the population of mobile carriers available for interfacial charge\n26\ntransfer is limited, which can lead to non-ideal interfacial responses. This kind of\nnon-ideal behavior often makes the Nyquist plot to appear more like a quarter circle\ninstead of a semicircle. In fact, in many reported studies, the EIS measurements are\nalso conducted under dark conditions, and the resulting Nyquist plots similarly exhibit\na quarter-circle shape (Adv. Funct. Mater, 2018, 28: 1705407; Nat. Commun, 2023, 14:\n7115):\n[Figure Redacted]\nFigure R5. EIS Nyquist plots of BP, CN, and 10% BP/CN under dark conditions.\n[Figure Redacted]\nFigure R6. EIS Nyquist plots of BCN, PuCN, and Ni -PuCN under dark conditions.\nSAPs\nBy contrast, under illumination, the generation of abundant photo-generated\ncarriers increases the carrier density and reduces the charge-transfer resistance, so the\nNyquist plots tend to be closer to a semicircle. This dark vs. light distinction has been\nreported both in the literature and our previous work, and is consistent with our\nclarification above (J. Am. Chem. Soc, 2017, 139: 13234-13242; Chem. Eng. J, 2020,\n384: 123258):\n[Figure Redacted]\nFigure R7. EIS Nyquist plots of BP, CN, and BP/CN under dark and light conditions.\n27\n[Figure Redacted]\nFigure R8. EIS Nyquist plots of 6BP/CN under dark and light conditions. Note: In the original\nliterature, the plots for dark and light conditions are presented in separate figures. For your\nconvenience, we have combined the data into a single figure.\nTherefore, the observed EIS shape in our work is consistent with the typical\nsemiconductor behavior under dark conditions. Here we would also like to clarify that\nalthough in some of our earlier studies, EIS measurements are occasionally performed\nunder illumination to obtain more ideal Nyquist plots, in our present work we no\nlonger employ illumination to optimize the EIS data. This is because performing EIS\nmeasurements in the dark enables a direct evaluation of the material’s intrinsic\ninterfacial charge-transfer resistance while avoiding interference from\nphoto-generated carriers. In recent years, our group consistently follows this\nexperimental strategy in all photocatalysis-related studies.\nTo address your concern, we have clearly specified in the Methods section that\nEIS measurements are conducted in the dark. We hope this clarification meets your\nexpectations. Please see page 24 lines 483-486 in the revised manuscript as follows:\nEIS and Mott-Schottky measurements were performed under dark conditions, while\nTPC measurements were conducted under illumination provided by a 300 W Xe lamp\n(PLS-SXE300, Beijing Perfect Light Technology Co., Ltd.). All measurements were\ncarried out at room temperature.\nReferences for Comment 30\n[1] Zheng, Y. et al. Black phosphorus and polymeric carbon nitride heterostructure for\nphotoinduced molecular oxygen activation. Adv. Funct. Mater.28, 1705407 (2018).\n[2] Zhang, X. et al. Developing Ni single-atom sites in carbon nitride for efficient\nphotocatalytic H O production. Nat. Commun. 14, 7115 (2023).\n2 2\n28\n[3] Zhu, M. et al. Metal-free photocatalyst for H evolution in visible to near-infrared\n2\nregion: black phosphorus/graphitic carbon nitride. J. Am. Chem. Soc. 139,\n13234-13242 (2017).\n[4] He, D. et al. Black phosphorus/graphitic carbon nitride: a metal-free photocatalyst\nfor “green” photocatalytic bacterial inactivation under visible light. Chem. Eng. J. 384,\n123258 (2020).\n31. The reference in comment 49 is not valid. Check all sources again.\nResponse: We thank the reviewer for the comment. In our first-round response,\nthe sentence in our original Comment 49 includes a reference: “The reason for this\nstatement is that it reflects the fundamental mechanism of the S-scheme\nheterojunction, which has also been documented in previous studies (Chem, 2020, 6,\n1543-1559).” We understand that the reviewer may have concerns regarding the\ncitation format or completeness. We apologize for the inconvenience caused in the\nfirst-round response, where all references cited in our comments are given in\nabbreviated form, which may have made it difficult for you to assess their validity. To\naddress these, in the current round, all references cited in our responses are provided\nin full immediately following each corresponding comment, including authors, title,\njournal, year, volume, and page numbers. We hope this practice resolves your concern.\nThe full details of the reference cited in our original Comment 49 are given below.\nReferences for Comment 31\n[1] Xu, Q. et al. S-scheme heterojunction photocatalyst. Chem.6, 1543-1559 (2020).\n32. In comment 50, is this sentence (In p-type semiconductors, the majority carriers\nare holes, and the hole density near the valence band is relatively low.) correct?\nResponse: We sincerely apologize for the confusion caused by our oversight. You\nare correct in pointing out the issue in our previous response. The sentence of “In\np-type semiconductors, the majority carriers are holes, and the hole density near the\nvalence band is relatively low.” is indeed incorrect. The issue arises from the word\n29\n“low”. In p-type semiconductors, the hole density near the valence band is actually\nhigh, not low as we mistakenly write.\nWe have carefully checked our revised manuscript. It is found that this sentence\nappears only in our first-round response to your original Comment 50 and does not\nappear in the current main text. Nevertheless, we are very grateful for your careful\nreading and for pointing out this error. We sincerely apologize for this oversight.\n33. Write the synthesis section in the main text.\nResponse: We thank the reviewer for the suggestion. Following your instruction,\nthe synthesis procedures have been incorporated into the main text. Specifically, they\nare integrated into the Methods section, which is placed after the Results and\nDiscussion section, thereby also complying with the editor’s guidance. In the email,\nthe editor specifically suggests: “For Comment 31, the synthesis details may be\nplaced in the Methods section following the Results and Discussion. In your rebuttal\nletter, you may wish to mention to Reviewer #3 that this formatting guidance was\nprovided by the editorial office.” We hope that this practice meets your expectations.\n34. In comment 52, “Has it been tested experimentally or is it only theoretical?”\nResponse: We thank the reviewer for the comment. In your original Comment 52,\nyou ask whether the type of semiconductor affects the design of S-scheme\nheterojunctions. Our statement is that the semiconductor type (n-type or p-type)\ndoes not influence the design of S-scheme heterojunctions. In this review round, you\nfurther ask, “Has it been tested experimentally or is it only theoretical?” We apologize\nfor the lack of clarity in our previous response. Here, we first provide a concise and\ndirect answer: our previous statement has been both experimentally validated and\ntheoretically supported. A more detailed explanation is provided below.\nFirstly, from a theoretical perspective, the construction of an S-scheme\nheterojunction primarily relies on two prerequisites: (i) the two semiconductors must\nhave appropriate band structures to achieve a staggered alignment, and (ii) there\nmust be a sufficiently large Fermi level difference to generate an internal electric field\nthat drives directional charge transfer. These two factors are decisive for establishing the\nare met, combinations of n-n, p-p, p-n, or n-p semiconductors can all form an\nS-scheme heterojunction. The above viewpoint is supported by numerous leading\nstudies. For your convenience, we provide below a relevant figure from a\nrepresentative literature (Adv. Mater, 2022, 34: 2107668):\n[Figure Redacted]\nFigure R9. Four types of S-scheme heterojunctions.\nSecondly, various experimental results have also confirmed our statement.\nExperimental studies show that, in practice, n-n, p-p, p-n, and n-p combinations, can\nform an effective S-scheme charge transfer pathway, provided the two prerequisites\n(as discussed in the above paragraph) are satisfied. For your convenience, we present\nhere some related works published very recently, illustrating the formation of\nS-scheme heterojunctions in n-n (J. Environ. Chem. Eng, 2025, 13: 118625), p-p (Sci.\nRep, 2025, 15: 10789), p-n (Small, 2024, 20: 2306563), and n-p (J. Mater. Sci.\nTechnol, 2024, 170: 200-211) combinations. Based on the discussion above, it can be\nconcluded that our statement has been both experimentally validated and theoretically\nsupported. We hope that our response addresses your concern.\nReferences for Comment 34\n[1] Zhang, L. et al. Emerging S-scheme photocatalyst. Adv. Mater. 34, 2107668\n(2022).\n[2] Nguyen, H. P. et al. Interfacial engineering of ZnSn(OH) /SnO S-scheme\n6 2\nheterojunctions for high-performance solar-light-driven photocatalytic nitric oxide\noxidation. J. Environ. Chem. Eng. 13, 118625 (2025).\n[3] Rezaei, M. M. et al. S-scheme heterojunction of MoO nanobelts and MoS\n3 2\n31\nnanoflowers for photocatalytic degradation. Sci. Rep. 15, 10789 (2025).\n[4] Hu, X. et al. Photoreduction of aqueous protons coupling with alcohol oxidation\non a S-scheme heterojunction photocatalyst MnO/carbon nitride. Small. 20, 2306563\n(2024).\n[5] Zhao, Y. et al. Bi WO /AgInS S-scheme heterojunction: efficient\n2 6 2\nphotodegradation of organic pollutant and toxicity evaluation. J. Mater. Sci. Technol.\n170, 200-211 (2024).\n35. In comment 53, is the difference between 0.5 and 1 due to experimental error?\nWrite another reason.\nResponse: We thank the reviewer for the comment. During the optimization of a\ncertain component’s doping level in a semiconductor photocatalyst, the photocatalytic\nactivity of the catalyst typically exhibits a “rise-and-fall” trend. It is therefore very\ncommon that samples with doping levels below and above the optimal value show\ncomparable photocatalytic activities, a phenomenon that has been widely reported in\nthe literature.\nFor example, in a study by Ran et al., a phosphorene/g-C N heterojunction with\n3 4\n0.6 wt% of phosphorene exhibits a H evolution rate of 139 μmol h−¹ g−¹, while a\n2\nphosphorene/g-C N heterojunction with 9.5 wt% of phosphorene shows a very\n3 4\nsimilar activity of 127 μmol h−¹ g−¹ (Adv. Mater, 2018, 30: 1800128). For your\nconvenience, we have included the relevant figure below, with the red boxes\nhighlighting the two samples that exhibit similar activities despite different\nphosphorene doping levels:\n[Figure Redacted]\nFigure R10. Photocatalytic H -production activities of the samples.\n2\n3 4\nCDots doping levels display nearly identical H evolution activities (Science, 2015,\n2\n347: 970-974). We have included the corresponding figure below, with the blue boxes\nmarking the two samples with similar activities but different CDots doping amounts:\n[Figure Redacted]\nFigure R11. Photocatalytic H -production activities of the samples.\n2\nalso be observed in other photocatalytic reactions, such as H O production, where,\n2 2\nwithin the range below and above the optimal doping level, different samples exhibit\ncomparable photocatalytic activities (Nat. Commun, 2023, 14: 2493):\n[Figure Redacted]\nFigure R12. Photocatalytic H O -production activities of the samples.\n2 2\nAlso, in photocatalytic disinfection reactions, similar trends are often observed.\nFor example, in one study, the photocatalytic disinfection activity of the catalyst\nreaches its maximum when the Bi MoO doping amount is 20 wt% in\n2 6\nBi MoO -g-C N composite. For materials with doping amounts below and above 20\n2 6 3 4\nwt%, the photocatalytic disinfection activities remain very close, which is reflected in\nthe figure by multiple curves highly overlapping (J. Hazard. Mater, 2017, 321:\n183-192). For your convenience, we have included the relevant figure below, with the\nred box highlighting the samples that exhibit similar activities despite different\nBi MoO doping levels:\n2 6\n33\n[Figure Redacted]\nFigure R13. Photocatalytic water disinfection activities of the samples.\nBased on your comment, we have carefully reviewed and summarized the above\nliterature, leading to a reasonable explanation: “when a certain component’s doping\nlevel is below the optimal value, limited interfacial contact restricts photocatalytic\nactivity, while excessive doping leads to overcoverage that suppresses the activity.”\nWe hope this explanation addresses your concern.\nReferences for Comment 35\n[1] Ran, J. et al. Metal-free 2D/2D phosphorene/g-C N Van der Waals heterojunction\n3 4\nfor highly enhanced visible-light photocatalytic H production. Adv. Mater. 30,\n2\n1800128 (2018).\n[2] Liu, J. et al. Metal-free efficient photocatalyst for stable visible water splitting via\na two-electron pathway. Science.347, 970-974 (2015).\n[3] Wang, W. et al. Photothermal-enabled single-atom catalysts for high-efficiency\nhydrogen peroxide photosynthesis from natural seawater. Nat. Commun. 14, 2493\n(2023).\n[4] Li, J. et al. In situ growing Bi MoO on g-C N nanosheets with enhanced\n2 6 3 4\nphotocatalytic hydrogen evolution and disinfection of bacteria under visible light\nirradiation. J. Hazard. Mater.321, 183-192 (2017).\n36. Which active species plays a key role?\nResponse: We thank the reviewer for the comment. Based on our experimental\nresults, •O − plays the most critical role in the photocatalytic disinfection process.\nThe experimental results illustrated in Figure S17 indicate the participation of four\n34\ndistinct ROS for bacterial inactivation, with contributions of •O − > 1O > H O >\n2 2 2 2\n•OH.\n35"}, {"round": 2, "reviewer_comments": {"reviewer_1": "The authors have provided reasonable explanations for some of my concerns, which I find acceptable.", "reviewer_2": "After revised，this manuscript has clarfied questions and it can be Accepted as current form.", "reviewer_3": "Manuscript Number: NCOMMS-25-15152\nJournal:\nTitle: Dual Optimization of Kinetic and Thermodynamic Constraints in Photo-induced Charge Carriers for Subminute\nPhotocatalytic Water Disinfection under Real Sunlight\nGeneral Comments:\nThe authors of this paper investigated the Dual Optimization of Kinetic and Thermodynamic Constraints in Photo-induced\nCharge Carriers for Subminute Photocatalytic Water Disinfection under Real Sunlight .In addition, the graphic should be\nadded to the main text. There are still questions that need to be answered. In light of this issue and the comments described\nbelow\nDetailed comments\n1- Please write the names of the synthesized compounds in the title to be specific and informative.\n2- This sentence in comment 8 ( Bismuth oxyhalides (BiOX, X = Cl, Br, I) are a class of V−VI−VII ternary oxide\nsemiconductors characterized by a layered tetragonal matlockite structure, in which…) needs to be changed.\n3- Please change this sentence in comment 8 from (BiOX exhibit several advantageous physicochemical properties … ) to (\nBiOX compounds exhibit several advantageous physicochemical properties …).\n4- This sentence in comment 9, Write the phrase to produse in leading to the formation.\n5- Did you check the effect of pH factor?\n6- In line 61 of the main article, what is the pronoun their ( energy losses in the processes or charge carrier transfer )?\n7- Which stage does this sentence (‘the simultaneous reduction of energy …’) refer to?\n8- Please put graphical abstract in the main text.\n9- In the graphical abstract write the full names of the compounds.\n10- Please explain this sentence (the formation of ROS is thermodynamically limited, leading to energy loss.) further in\nresponse to comment 12. Is real energy wasted or is it thermodynamically impossible?\n11- Please provide 13 references for comment.\n12- In comment 13, use the phrase on the other hand, instead of on one hand .\n13- In comment 14, does the photocatalytic process of adsorption and desorption occur on the surface of the photocatalyst in\nthe dark phase?\n14- How does the internal electric field cause efficient electron and hole separation?\n15- This sentence should be corrected in comment 15 (Bismuth oxyhalides (BiOX, X = Cl, Br, I) are a class of V−VI−VII\nternary oxide) , Because BiOX is an oxyhalide compound, not a simple oxide.\n16- Check reference 2 again in comment 18.\n17- In comment 18, the expression ( result, can offer a rough estimation for the conduction-band value) is used, which is a\nlimited and imprecise value. Please check.\n18- In comment 19, sentence( our study aims to demonstrate that optimizing the compatibility between the macroscopic\ngeometric structures) , which parameter is it? Layer dimensions or number of layers or...\n19- In comment 20, what do you mean by bismuth being layered? Which factor plays a more important role? Layer thickness\nor number of layers or layer spacing or.....\n20- In comment 21, the word anticipated is used. Does this mean that it has not been proven yet?\n21- The reference in comment 24 is not valid. Please replace it.\n22- Comment 24: You wrote that you did not complete the step. How was the oxide layer removed?\n23- In comment 26, you wrote sentence )the overall morphology of BP does not fundamentally change) . Please write more\nprecisely.\n24- Please provide 27 references for comment.\n25- Write other ( advantage of the method ultrasonic exfoliation process ) in response to comment 28.\n26- Please provide 28 references for comment.\n27- In comment 33, do other parameters such as solvent viscosity and polarity also have an effect?\n28- In comment 42, Explain accumulation of lines further. What does it represent?\n29- In comment 43, Sentence (The number of layers of PNs in the heterostructure is not expected to significantly affect the\nqualitative … ) , do you have real data or are you just expecting it?\n30- In comment 44 , Why aren't curves EIS arc-shaped?\n31- The reference in comment 49 is not valid. Check all sources again.\n32- In comment 50, is this sentence ( In p-type semiconductors, the majority carriers are holes, and the hole density near the\nvalence band is relatively low.) correct?\n33- Write the synthesis section in the main text.\n34- In comment 52, \"Has it been tested experimentally or is it only theoretical?\"\n35- In comment 53, is the difference between 0.5 and 1 due to experimental error? Write another reason.\n36- Which active species plays a key role?"}, "author_response": "ResponseLetter\nThe authors are grateful for the editor’s and reviewers’ dedicated efforts in improving\nthis paper. This manuscript has been revised to address all the issues raised by the\nreviewers. Reviewers’ suggestions are in black italic type and our responses are indent\nand in normal font. The revised text as it appears in the manuscript is in blue.\nResponses to the comments and suggestions are listed below.\nReviewer #1\nComments: The authors have provided reasonable explanations for some of my\nconcerns, which I find acceptable.\nResponse: Thanks for your positive comment. We are pleased that the current\nversion meets your expectations.\nReviewer #2\nComments: After revised, this manuscript has clarified questions and it can be\nAccepted as current form.\nResponse: Thanks for your recommendation for acceptance.\nReviewer #3\nComments: The authors of this paper investigated the Dual Optimization of Kinetic\nand Thermodynamic Constraints in Photo-induced Charge Carriers for Subminute\nPhotocatalytic Water Disinfection under Real Sunlight. In addition, the graphic\nshould be added to the main text. There are still questions that need to be answered.\nIn light of this issue and the comments described below.\nResponse: We would like to express our sincere gratitude to Reviewer #3 for the\ncontinued effort and careful reading of our revised manuscript during the second\nround of review.\nIn this round of revision, we have thoroughly addressed each of your new\ncomments. Specifically, on one hand, some of your comments pertain to\nmodifications of the manuscript itself, and we have implemented all the changes you\nsuggested (only in a few cases, mainly, where your suggestions do not fully align with\nthe editor’s guidance, we try to find a balanced solution while still doing our best to\nrespect and incorporate your suggestions). On the other hand, some comments are\nfollow-up questions regarding certain statements or expressions in our previous\nresponses. We apologize if our earlier replies are overly concise and cause any\nconfusion. In this round, we provide more detailed explanations, cite relevant\nreferences, and include related figures for your convenience.\nthe manuscript into its currently improved form. We hope that the revised version now\nmeets your expectations and that our new responses address your remaining concerns.\n1. Please write the names of the synthesized compounds in the title to be specific and\ninformative.\nResponse: Thanks for your suggestion. In response, we have included the name\nof the synthesized material in the title. The title has been determined as “2D/2D\nphosphorene/BiOI S-scheme heterojunction for subminute photocatalytic water\ndisinfection under real sunlight”. Please see the title page in the revised manuscript.\n2. This sentence in comment 8 (Bismuth oxyhalides (BiOX, X = Cl, Br, I) are a class of\nV−VI−VII ternary oxide semiconductors characterized by a layered tetragonal\nmatlockite structure, in which…) needs to be changed.\nResponse: We thank the reviewer for pointing this out. In this round of your\ncomments, Comment 15 also refers to this sentence. Your original note is “This\nsentence should be corrected in comment 15 (Bismuth oxyhalides (BiOX, X = Cl, Br, I)\nare a class of V−VI−VII ternary oxide), Because BiOX is an oxyhalide compound, not\na simple oxide.” We agree that the sentence should be corrected, as bismuth\noxyhalides should not be simply classified as an oxide. In the revised version, based\non your comment, we now describe bismuth oxyhalides as “ternary semiconductor\ncompounds”, which is also consistent with the descriptions found in the literature\n(Environ. Sci-Nano, 2014, 1: 90-112). Please see page 1 in the revised Supplementary\nInformation as follows:\nBismuth oxyhalides (BiOX, X = Cl, Br, I) are important ternary semiconductor\ncompounds [4].\nReferences for Comment 2\n[1] Ye, L. et al. Recent advances in BiOX (X = Cl, Br and I) photocatalysts: synthesis,\nmodification, facet effects and mechanisms. Environ. Sci-Nano. 1, 90-112 (2014).\n2\n3. Please change this sentence in comment 8 from (BiOX exhibit several\nadvantageous physicochemical properties…) to (BiOX compounds exhibit several\nadvantageous physicochemical properties…).\nResponse: Thanks for your suggestion. We have made the revision in accordance\nwith your instruction. Please see page 1 in the revised Supplementary Information as\nfollows:\nBiOX compounds exhibit several advantageous physicochemical properties.\n4. This sentence in comment 9, Write the phrase to produse in leading to the\nformation.\nResponse: Thanks for your suggestion. In response, we have replaced “to\nproduce” with “leading to the formation of” to make the logical relationship between\nthe redox reactions and the formation of ROS clearer. Please see page 3 lines 47-50 in\nthe revised manuscript as follows:\nGenerally, a photocatalyst with an appropriate bandgap can harness visible light to\ngenerate electron-hole pairs, which initiate redox reactions, leading to the formation\nof reactive oxygen species (ROS).\n5. Did you check the effect of pH factor?\nResponse: We sincerely appreciate your insightful comment regarding the effect\nof pH. You are correct that in our original version this aspect is not clearly indicated.\nThe redox potentials relevant to ROS formation reported in the manuscript are\nreferenced to NHE at pH 7 (Nat. Nanotechnol, 2016, 11: 1098-1104; Angew. Chem.\nInt. Ed. Engl, 2020, 59: 5218-5225). We have revised the corresponding sentence to\nmake this explicit. Please see page 3 lines 50-53 in the revised manuscript as follows:\nTheoretically, the redox potentials relevant to ROS formation are −0.33 V (O /•O −)\n2 2\nand 0.28 V (O /H O ) for electron-driven oxygen reduction, and 1.90 V (H O/•OH)\n2 2 2 2\nfor hole-driven water oxidation, all referenced to NHE at pH 7 [7, 8].\nReferences for Comment 5\n3\n[1] Liu, C. et al. Rapid water disinfection using vertically aligned MoS nanofilms and\n2\nvisible light. Nat. Nanotechnol.11, 1098-1104 (2016).\n[2] Xia, P. et al. Designing a 0D/2D S-scheme heterojunction over polymeric carbon\nnitride for visible-light photocatalytic inactivation of bacteria. Angew. Chem. Int. Ed.\nEngl. 59, 5218-5225 (2020).\n6. In line 61 of the main article, what is the pronoun their (energy losses in the\nprocesses or charge carrier transfer)?\nResponse: Thanks for pointing this out. We have noticed that the pronoun “their”\ncould be misinterpreted. So we have revised the sentence to explicitly use “these\ncarriers” when referring to ROS generation, thereby eliminating the ambiguity caused\nby the previous pronoun “their”. Please see page 3 lines 59-62 in the revised\nmanuscript as follows:\nHowever, effectively utilizing absorbed visible light for microbial inactivation\nrequires minimizing energy losses both during charge carrier transfer across the\nheterojunction interfaces and during the subsequent ROS generation by these carriers,\na limitation that current heterojunctions remain unable to overcome.\n7. Which stage does this sentence (‘the simultaneous reduction of energy…’) refer to?\nResponse: We appreciate your careful reading and valuable question. The\nsentence refers to two consecutive stages following light absorption: (1) charge carrier\ntransfer across the heterojunction interfaces, and (2) subsequent ROS generation by\nthese carriers. The ambiguity may have arisen from the use of the term “simultaneous”\n(which has now been removed), which could imply that these two processes occur at\nthe same time. To clarify this point, we have revised the text by adding “subsequent”\nto indicate their temporal sequence. In addition, the revised sentence adopts the “both\nA and B” structure to explicitly emphasize the need to reduce energy losses in both\nprocesses. We hope these revisions help eliminate any potential ambiguities and\naddress your concerns. Please see page 3 lines 59-62 in the revised manuscript as\nfollows:\nrequires minimizing energy losses both during charge carrier transfer across the\nheterojunction interfaces and during the subsequent ROS generation by these carriers,\na limitation that current heterojunctions remain unable to overcome.\n8. Please put graphical abstract in the main text.\nResponse: Thanks for your suggestion. The journal editor has informed us via\nemail with the original note stated “regarding Comments 8 and 9, graphical abstract is\nnot permitted. In your rebuttal letter, you may wish to mention to Reviewer #3 that\nthis formatting guidance was provided by the editorial office.” Accordingly, it appears\nthat graphical abstracts are not allowed in Nature Communications.\nIn response, and out of respect for your valuable input, we have redefined this\nfigure as a schematic illustration of the photocatalytic water disinfection mechanism\nrather than a graphical abstract and placed it in the revised Supplementary\nInformation. We hope this modification addresses your concern while complying with\nthe journal’s requirements. Please see page 16 lines 313-314 in the revised manuscript\nas follows:\nThe mechanism of photocatalytic water disinfection by 0.8PNs/BS is shown in Figure\nS19.\nFigure S19. Schematic illustration of 0.8PNs/BS-mediated photocatalytic water disinfection.\n9. In the graphical abstract write the full names of the compounds.\nResponse: Thanks for your suggestion. As requested, we have incorporated the\n5\nfull names of the materials into the graphical abstract. However, the journal editor has\ninformed us via email with the original note stated “regarding Comments 8 and 9,\ngraphical abstract is not permitted. In your rebuttal letter, you may wish to mention to\nReviewer #3 that this formatting guidance was provided by the editorial office.”\nAccordingly, it appears that graphical abstracts are not allowed in Nature\nCommunications.\nIn response, and out of respect for your valuable input, we have redefined this\nfigure as a schematic illustration of the photocatalytic water disinfection mechanism\nrather than a graphical abstract and placed it in the revised Supplementary\nInformation. We hope this modification addresses your concern while complying with\nthe journal’s requirements. Please see page 30 in the revised Supplementary\nInformation as follows:\nFigure S19. Schematic illustration of 0.8PNs/BS-mediated photocatalytic water disinfection.\n10. Please explain this sentence (the formation of ROS is thermodynamically limited,\nleading to energy loss.) further in response to comment 12. Is real energy wasted or is\nit thermodynamically impossible?\nResponse: Thanks for your comment. The sentence you referred to originates\nfrom our previous response: “If the conduction band minimum or valence band\nmaximum of the photocatalyst does not possess sufficient potential to drive the\ndesired redox reactions, the formation of ROS is thermodynamically limited, leading\nto energy loss.” We understand that the phrase “thermodynamically limited” may\nappear ambiguous without further clarification. To address your concern, we would\n6\nlike to further clarify this point in more detail. We would like to cite a sentence from a\nclassic reference (Chem, 2020, 6: 1543-1559), as its explanation is more intuitive and\neasier to understand: [Redacted]. Please note that the “Figures 2B and 2C” mentioned\nin this paragraph corresponds to Figure R1 shown below.\n[Figure Redacted]\nFigure R1. A ball collided by another ball from (B) a high and (C) a low altitude.\nIn more detail, for example, in the case of O reduction to H O , the\n2 2 2\nthermodynamic driving force of this reaction depends on the difference between the\nconduction-band potential of a semiconductor and the redox potential of this reaction\n(O /H O , 0.28 V versus NHE). For instance, one semiconductor with a\n2 2 2\nconduction-band potential of 0.26 V versus NHE provides a stronger thermodynamic\ndriving force for this reaction than another semiconductor with a conduction-band\npotential of 0.27 V versus NHE. Conversely, if a semiconductor exhibits a\nconduction-band potential (e.g., 0.29 V versus NHE) that is less negative than the\nredox potential of the reaction (0.28 V versus NHE), the photo-generated electrons\nwould not have sufficient thermodynamic driving force to initiate this reduction\nreaction (in analogy to the example of the ball collision above, this situation is like\nwhen the red ball lies to the right of the green ball—it cannot strike the green ball to\nlift it to any height on the right). In this case, the photo-generated electrons excited by\nlight energy cannot produce H O . Their eventual fate is well-known: they recombine\n2 2\nwith photo-generated holes, releasing the absorbed solar energy as heat (ACS. Omega,\n7\n2020, 5: 31644-31656). This portion of energy is therefore wasted due to the absence\nof H O formation, which is what we mean by “the formation of ROS is\n2 2\nthermodynamically limited, leading to energy loss.” We hope this detailed explanation\nresolves your query.\nReferences for Comment 10\n[1] Teng, Z. et al. Edge-functionalized g-C N nanosheets as a highly efficient\n3 4\nmetal-free photocatalyst for safe drinking water. Chem.5, 664-680 (2019).\n[2] Hendi, A. H. et al. Visible light-driven photoelectrocatalytic water splitting using\nZ-scheme Ag-decorated MoS /RGO/NiWO heterostructure. ACS. Omega. 5,\n2 4\n31644-31656 (2020).\n11. Please provide 13 references for comment.\nResponse: We thank the reviewer for the comment. In our previous response to\nyour Comment 13, the modification we made lacks literature support. We have now\nincluded an appropriate reference (Chem. Commun, 2014, 50: 10768-10777). The\noriginal text from this work states: “In comparison with other 2D material based\ncomposites (i.e., 0D-2D and 1D-2D composites), a solid construction can be achieved\nby the 2D-2D layered composites due to the large contact surface between the sheets.\nMoreover, the large contact area of the 2D layered composite should lead to more\nefficient interfacial charge transfer.” We believe this statement strongly supports our\npoint. Please see page 4 lines 76-79 in the revised manuscript as follows:\nOn one hand, both PNs and BS possess a 2D nanostructure, enabling them to form\nintimate “face to face” contacts with robust interfacial interactions for fast charge\ncarrier transfer (2D/2D heterojunctions provide larger interfacial contact areas than\nother counterparts, e.g., 0D/2D or 1D/2D) [19].\n[19] Low, J., Cao, S., Yu, J., Wageh, S. Two-dimensional layered composite\nphotocatalysts. Chem. Commun. 50, 10768-10777 (2014).\n12. In comment 13, use the phrase on the other hand, instead of on one hand.\nComment 13, we have taken into account not only the revised sentence itself, but also\nits context within the surrounding text. Specifically, the sentence we revised is\nfollowed by a sentence beginning with “On the other hand...” In this context,\nbeginning our revised sentence with “On one hand...” is appropriate. Together, the\ntwo sentences clearly convey the different aspects intended by the “On one hand…\nOn the other hand…” construction. For your convenience, we have provided these\ntwo consecutive sentences below (they appear on page 4 lines 76-81 in the revised\nmanuscript):\nOn one hand, both PNs and BS possess a 2D nanostructure, enabling them to form\nintimate “face to face” contacts with robust interfacial interactions for fast charge\ncarrier transfer (2D/2D heterojunctions provide larger interfacial contact areas than\nother counterparts, e.g., 0D/2D or 1D/2D) [19]. On the other hand, a well-defined\nS-scheme band alignment results in the accumulation of electrons and holes with\nenhanced redox abilities for elevated ROS generation.\n13. In comment 14, does the photocatalytic process of adsorption and desorption\noccur on the surface of the photocatalyst in the dark phase?\nResponse: We thank the reviewer for raising this important question. In our\nprevious response, we may not have fully understood your concern. It appears that\nyou are asking whether adsorption and desorption of bacteria occur on the surface of\nthe photocatalyst in the dark.\nIn fact, you may also have noticed that, in studies on photocatalytic organic\npollutant degradation, the adsorption-desorption behavior of organic molecule on the\nphotocatalyst surface is an essential aspect that is systematically examined in almost\nall relevant literature (Appl. Catal. B-Environ, 2015, 176-177: 240-248). Researchers\nin this field, including our group, routinely investigate how organic molecules interact\nwith the catalyst surfaces through such adsorption-desorption processes.\nHowever, for photocatalytic bacterial inactivation, based on our research\nexperience and a thorough review of the literature, there is currently no research\n9\nframework analogous to “adsorption-desorption” applied to bacteria (Adv. Mater,\n2024, 37: 2410221; Nat. Nanotechnol, 2016, 11: 1098-1104; Nat. Water, 2023, 1:\n462-470). This is because adsorption refers to the accumulation of “molecules or ions”\nfrom gases or liquids on a solid surface, and bacteria, being much larger than such\nmolecules or ions, cannot be regarded as adsorption targets. To clarify, we directly\nquote the original text from an authoritative textbook (Environmental Organic\nChemistry, John Wiley & Sons: New York, 2002, p 277):\n[Redacted]\nBacteria are µm-sized living entities, as shown in Figure R2 below (Environ. Sci.\nTechnol, 2018, 52: 4774-4784). They are even much larger than the nm-sized\nphotocatalysts we prepare. Therefore, bacteria do not fall under the definition of\nmolecules or ions for adsorption. In summary, to the best of our knowledge, a\nresearch framework analogous to “adsorption-desorption” has not been applied to\nbacteria in previous studies related to photocatalytic water disinfection, and\naccordingly, it is not employed in our present work either (Adv. Mater, 2024, 37:\n2410221; Nat. Nanotechnol, 2016, 11: 1098-1104; Nat. Water, 2023, 1: 462-470).\n[Figure Redacted]\nFigure R2. SEM image of bacteria, highlighting that they are µm-sized living entities (scale bar:\n2\nµm).\nReferences for Comment 13\n[1] Liang, R. et al. A simple strategy for fabrication of Pd@MIL-100(Fe)\nnanocomposite as a visible-light-driven photocatalyst for the treatment of\n10\npharmaceuticals and personal care products (PPCPs). Appl. Catal. B-Environ.\n176-177, 240-248 (2015).\n[2] Yang, H. et al. Visible‐light‐induced rapid elimination of antibiotic resistance\ncontaminations using graphitic carbon nitride tailored with carrier confinement\ndomains. Adv. Mater. 37, 2410221 (2024).\n[3] Liu, C. et al. Rapid water disinfection using vertically aligned MoS nanofilms and\n2\nvisible light. Nat. Nanotechnol.11, 1098-1104 (2016).\n[4] Wu, T. et al. Solar-driven efficient heterogeneous subminute water disinfection\nnanosystem assembled with fingerprint MoS . Nat. Water.1, 462-470 (2023).\n2\n[5] Schwarzenbach, R. P. et al. Environmental Organic Chemistry, John Wiley &\nSons: New York, p 277 (2002).\n[6] Wang, T. et al. Enhanced visible-light-driven photocatalytic bacterial inactivation\nby ultrathin carbon-coated magnetic cobalt ferrite nanoparticles. Environ. Sci. Technol.\n52, 4774-4784 (2018).\n14. How does the internal electric field cause efficient electron and hole separation?\nResponse: We thank the reviewer for this valuable comment. To carefully explain\nhow the internal electric field causes efficient electron-hole separation, we have\nselected a schematic illustration from a key literature (Nat. Commun, 2024, 15: 4807),\nas shown below:\n[Figure Redacted]\nFigure R3. Schematic illustration of the charge transfer mechanism in an S-type heterojunction.\nIn this figure, the band structure of a typical S-scheme heterojunction is depicted.\nThe light blue arrow indicates the direction of the internal electric field. The electric\nfield points from the positively charged region to the negatively charged region.\nUnder this field, electrons (negatively charged) experience a force opposite to the\n11\nfield direction, while holes (positively charged) are driven along the field direction.\nAs a result, the electric field facilitates the recombination of photo-excited electrons\nin the conduction band of the left-hand component with photo-induced holes in the\nvalence band of the right-hand component. As a result, photo-generated charge\ncarriers with strong redox capabilities in the conduction band of the right-hand\ncomponent and the valence band of the left-hand component are preserved, thereby\nenabling the so-called “efficient electron and hole separation.” This mechanism is\nconsistent with previously reported studies (Angew. Chem. Int. Ed. Engl, 2020, 59:\n5218-5225; Chem, 2020, 6: 1543-1559). We hope this explanation addresses your\nquestion.\nReferences for Comment 14\n[1] Deng, X. et al. Ultrafast electron transfer at the In O /Nb O S-scheme interface\n2 3 2 5\nfor CO photoreduction. Nat. Commun.15, 4807 (2024).\n2\n[2] Xia, P. et al. Designing a 0D/2D S-scheme heterojunction over polymeric carbon\nnitride for visible-light photocatalytic inactivation of bacteria. Angew. Chem. Int. Ed.\nEngl. 59, 5218-5225 (2020).\n[3] Xu, Q. et al. S-scheme heterojunction photocatalyst. Chem.6, 1543-1559 (2020).\n15. This sentence should be corrected in comment 15 (Bismuth oxyhalides (BiOX, X =\nCl, Br, I) are a class of V−VI−VII ternary oxide), Because BiOX is an oxyhalide\ncompound, not a simple oxide.\nResponse: Thanks for pointing this out. We agree that the sentence should be\ncorrected, as bismuth oxyhalides should not be simply classified as an oxide. In the\nrevised version, based on your comment, we now describe bismuth oxyhalides as\n“ternary semiconductor compounds”, which is also consistent with the descriptions\nfound in the literature (Environ. Sci-Nano, 2014, 1: 90-112). Please see page 1 in the\nrevised Supplementary Information as follows:\nBismuth oxyhalides (BiOX, X = Cl, Br, I) are important ternary semiconductor\ncompounds [4].\n1. Ye, L. et al. Recent advances in BiOX (X = Cl, Br and I) photocatalysts: synthesis,\nmodification, facet effects and mechanisms. Environ. Sci-Nano. 1, 90-112 (2014).\n16. Check reference 2 again in comment 18.\nResponse: We appreciate the reviewer’s reminder. The section in the\nSupplementary Information citing Reference 2 (Adv. Mater, 2018, 30: 1800128) reads\nas follows: “PNs, known as the few-layer form of BP, have recently garnered\nsignificant attention owing to the unique physicochemical properties: (i) a high\nsurface-to-volume ratio with abundant accessible active sites; (ii) a distinctive\nlayer-dependent direct bandgap, coupled with tunable redox properties of charge\ncarriers; (iii) a broad light absorption capacity across the entire visible-light region [2].\nBenefiting from these characteristics, PNs have been explored in diverse\nphotocatalytic applications, including water splitting, pollutant degradation, and H O\n2 2\nproduction [2, 3].”\nWe have carefully re-examined Reference 2, which states that “Recently,\nmetal-free phosphorene has attracted tremendous attention as an emerging 2D\nmaterial due to its unique features of i) thickness dependent band gap ranging from\n0.3 to 2.0 eV,[14,50-56] ii) high charge mobility of ≈ 1000 cm2 V−1 s−1 ,[51,53,56] and iii)\nlarge specific surface area with high ratio of exposed surface atoms. [14,53,56]” In\naddition, Reference 2 investigates the optical absorption properties of the materials by\nUV-vis diffuse reflectance spectroscopy and reports that “an increased light\nabsorption in the range of ≈ 460-800 nm is ascribed to the presence of phosphorene.”\nThus, the content of Reference 2 aligns well with our corresponding statements in the\nSupplementary Information: “PNs, known as the few-layer form of BP, have recently\ngarnered significant attention owing to the unique physicochemical properties: (i) a\nhigh surface-to-volume ratio with abundant accessible active sites; (ii) a distinctive\nlayer-dependent direct bandgap, coupled with tunable redox properties of charge\ncarriers; (iii) a broad light absorption capacity across the entire visible-light region\n13\n[2].”\nMoreover, Reference 2 reports on photocatalytic water splitting, which supports\nthe subsequent sentence in Supplementary Information mentioning “Benefiting from\nthese characteristics, PNs have been explored in diverse photocatalytic applications,\nincluding water splitting, pollutant degradation, and H O production [2, 3].”\n2 2\nTherefore, we believe that the citation of Reference 2 in this context is\nappropriate. We hope this clarification resolves your concern.\nReferences for Comment 16\n[1] Ran, J. et al. Metal-free 2D/2D phosphorene/g-C N Van der Waals heterojunction\n3 4\nfor highly enhanced visible-light photocatalytic H production. Adv. Mater. 30,\n2\n1800128 (2018).\n17. In comment 18, the expression (result, can offer a rough estimation for the\nconduction-band value) is used, which is a limited and imprecise value. Please check.\nResponse: We appreciate the reviewer’s reminder. We would like to clarify that\nthe expression “rough estimation” does not imply any inaccuracy or unreliability of\nour results. In fact, it follows the conventional terminology used in Mott-Schottky\nanalysis. For n-type semiconductors, the Mott-Schottky test determines the flat-band\npotential instead of directly measuring the conduction-band minimum. Therefore,\ndescribing it as a “rough estimation” accurately reflects the methodological nature of\nthis approach rather than any imprecision in the data itself. In fact, such phrasing is\nwidely adopted in authoritative literature, such as Nat. Commun, 2019, 10: 2177,\nwhere it is stated that “The Mott-Schottky measurements conducted at three different\nfrequencies give the n-type semiconductor nature of ZIF-8 and the flat band position\nof ZIF-8 at ~−1.2V vs. NHE, which roughly equals to the bottom of conduction band\n(Supplementary Fig. 11).” As can be seen, this article also uses similar wording\n“roughly equals.” Avoiding such phrasing would actually make the description less\naccurate.\nTo ensure the reliability of our result, we further compare the obtained\n14\nconduction-band value with reported data for phosphorene. The conduction-band\nposition determined in our work (−0.44 V versus NHE) is in close agreement with that\nreported in literature (Adv. Mater, 2018, 30: 1800128; −0.40 V versus NHE).\nTherefore, although the term “rough estimation” is employed to reflect the\nmethodological convention of Mott-Schottky analysis, the derived conduction-band\nposition is scientifically reasonable and consistent with literature value.\nReferences for Comment 16\n[1] Li, P. et al. Metal-organic frameworks with photocatalytic bactericidal activity for\nintegrated air cleaning. Nat. Commun.10, 2177 (2019).\n[2] Ran, J. et al. Metal-free 2D/2D phosphorene/g-C N Van der Waals heterojunction\n3 4\nfor highly enhanced visible-light photocatalytic H production. Adv. Mater. 30,\n2\n1800128 (2018).\n18. In comment 19, sentence (our study aims to demonstrate that optimizing the\ncompatibility between the macroscopic geometric structures), which parameter is it?\nLayer dimensions or number of layers or...\nResponse: We appreciate the reviewer’s question. In our study, the term\n“macroscopic geometric structure” describes the overall geometrical configuration of\nthe heterojunction components (e.g., 0D, 2D, or 3D). In this context, both PNs and\nBiOX belong to the 2D category, and therefore, their geometric structures exhibit\ncompatibility. This concept, in fact, is explained in the Introduction section of the\nmain text, which is refined under your guidance in the first round revision. Please see\npage 4 lines 76-79 in the revised manuscript as follows:\nOn one hand, both PNs and BS possess a 2D nanostructure, enabling them to form\nintimate “face to face” contacts with robust interfacial interactions for fast charge\ncarrier transfer (2D/2D heterojunctions provide larger interfacial contact areas than\nother counterparts, e.g., 0D/2D or 1D/2D) [19].\n19. In comment 20, what do you mean by bismuth being layered? Which factor plays a\n15\nmore important role? Layer thickness or number of layers or layer spacing or.....\nResponse: Thanks for the comment. We have located our response to your\noriginal Comment 20, in which the term “layered BiOI” is used, which may have\ncaused some confusion. In short, in our previous reply, the term “layered BiOI” is\nused solely to describe the 2D morphology of BiOI (its nanosheet-like structure), and\nis by no means intended to refer to properties like the number of layers. Below, we\nprovide a detailed explanation of why this term is used.\nIn your original comment, you ask, “Does the layered structure of bismuth\ncompounds contribute to their photocatalytic activity?” In our original response to this\ncomment, we use the term “layered BiOI” just to match the wording you used, so it\nwould be easier to follow. In fact, this “layered BiOI” is exactly the same material as\nthe BiOI nanosheets (BS) mentioned in the main text. In the literature, the term\n“layered XXX” is commonly used to describe 2D morphologies, such as\nnanosheet-like or nanoflake-like structures, which accurately reflect the layered nature\nof the 2D materials. For instance, for the well-known 2D material g-C N , some\n3 4\nstudies refer to it as “g-C N nanosheets” (J. Am. Chem. Soc, 2017, 139: 13234-13242)\n3 4\nwhile others describe it as “layered g-C N ” (Adv. Funct. Mater, 2018, 28: 1800668).\n3 4\nThis illustrates that both terminologies are commonly accepted to denote the same\nstructural feature. We hope this clears up any confusion regarding the terminology.\nReferences for Comment 19\n[1] Zhu, M. et al. Metal-free photocatalyst for H evolution in visible to near-infrared\n2\nregion: black phosphorus/graphitic carbon nitride. J. Am. Chem. Soc. 139,\n13234-13242 (2017).\n[2] Kong, L. et al. g-C N loading black phosphorus quantum dot for efficient and\n3 4\nstable photocatalytic H generation under visible light. Adv. Funct. Mater. 28,\n2\n1800668 (2018).\n20. In comment 21, the word anticipated is used. Does this mean that it has not been\nproven yet?\n“anticipated” is simply used to introduce the following content. The sentence is\nstructured as “XXXX is anticipated” followed by “To confirm this, XXXX”,\nindicating that the anticipation is immediately addressed and verified in the\nsubsequent text. Below, we provide a detailed explanation.\nIn the context of the original sentence: “The observed “face to face” contact\nbetween the two 2D components, PNs and BS, within the constructed heterojunction,\nis anticipated to create a strong interfacial interaction between the layers.”, the term\n“anticipated” indeed indicates that the strong interfacial interaction has not yet been\ndirectly proven at that point in the text. This sentence serves primarily as a transition\nto introduce the subsequent text: “To confirm this, synchrotron-based X-ray\nabsorption near-edge structure (XANES) analysis is employed.” Reading these two\nsentences together clarifies that the anticipated interaction is immediately followed by\nexperimental verification, providing both logical flow and supporting evidence. We\nhope this clarification resolves your concern.\n21. The reference in comment 24 is not valid. Please replace it.\nResponse: We apologize for the inconvenience caused in the first-round response,\nwhere all references cited in our comments are given in abbreviated form, which may\nhave made it difficult for you to assess their validity. We understand that the reviewer\nmay have concerns regarding the citation format or completeness. We also note that,\na similar issue is raised by you in Comment 31 of the current round. To address these,\nin the current round, all references cited in our responses are provided in full\nimmediately following each corresponding comment, including authors, title,\njournal, year, volume, and page numbers. We hope this practice resolves your concern.\nNow, the reference in our original Comment 24 corresponds to the following\npassage in page 20 lines 387-390 in the revised manuscript (we reference this work\nbecause our procedure for removing the oxide layers of red phosphorus follows the\nmethod described therein): “In a standard experimental setup, commercial red\nphosphorus (2 g) was dispersed in 15 mL of H O and hydrothermally treated at 200°C\n2\n17\nfor 12 h to remove surface oxide layers, and then dried in an oven [9].”\n[9] Xia, D., Shen, Z., Huang, G., Wang, W., Yu, J. C., Wong, P. K. Red phosphorus: an\nEarth-abundant elemental photocatalyst for “green” bacterial inactivation under\nvisible light. Environ. Sci. Technol. 49, 6264-6273 (2015).\n22. Comment 24: You wrote that you did not complete the step. How was the oxide\nlayer removed?\nResponse: We thank the reviewer for the comment. We realize that in our\nfirst-round response, we may have misunderstood your question. It seems that you are\nasking whether the oxide layers on red phosphorus are removed using the\nhydrothermal method. The current version now explicitly states that the commercial\nred phosphorus is indeed treated hydrothermally to remove surface oxide layers. This\nprocedure ensures the removal of surface oxide layers prior to subsequent\nexperiments. Please see page 20 lines 387-390 in the revised manuscript as follows:\nIn a standard experimental setup, commercial red phosphorus (2 g) was dispersed in\n15 mL of H O and hydrothermally treated at 200°C for 12 h to remove surface oxide\n2\nlayers, and then dried in an oven [9].\n23. In comment 26, you wrote sentence (the overall morphology of BP does not\nfundamentally change). Please write more precisely.\nResponse: Thanks for the comment. In your original Comment 26, you inquire\nwhether the calcination temperature would affect the morphology of BP. Our response\nis “As long as the temperature is sufficient to enable complete sublimation of red\nphosphorus and interaction with the mineralizer, the overall morphology of BP does\nnot fundamentally change.” This sentence may appear somewhat general. Here, we\nwould like to clarify it more precisely.\nFor example, in a previous study (Cryst. Growth. Des, 2016, 16: 1096-1103), the\nsynthesis of BP is conducted by heating red phosphorus, tin, and iodine from room\ntemperature to 863 K (589.85°C) and maintaining this temperature for 2 h, followed\n18\nby cooling to 758 K (484.85°C) for 2 h, and then to 393 K (119.85°C). The resulting\nBP exhibits a typical 2D layered morphology, as shown below:\n[Figure Redacted]\nFigure R4. SEM images of BP in the literature.\nIn contrast, in our work, the synthesis of BP is carried out by heating red\nphosphorus, tin, and iodine to 600°C, holding for 2 h, then cooling to 490°C and\nmaintaining for 2 h, followed by gradual cooling to 120°C. The obtained BP also\nshows a 2D layered morphology, as shown below:\nFigure S6. SEM images of BP.\nClearly, although the calcination temperature differ between the literature and\nour experiment, both prepared BP materials show a 2D morphology. Therefore, what\nwe intended to convey is that within the temperature range sufficient to ensure\ncomplete sublimation of red phosphorus and effective mineralizer-assisted growth,\nvariations in calcination temperature does not significantly alter the 2D morphology\nof BP. To make this statement more precise, the original sentence can be revised to\n“As long as the temperature is sufficient to ensure complete sublimation of red\nphosphorus and its interaction with the mineralizer, BP maintains its characteristic 2D\n19\nlayered morphology.” We hope that this clarification addresses your concern.\nReferences for Comment 23\n[1] Zhao, M. et al. Growth mechanism and enhanced yield of black phosphorus\nmicroribbons. Cryst. Growth. Des.16, 1096-1103 (2016).\n24. Please provide 27 references for comment.\nResponse: We thank the reviewer for the comment. In response to your original\nComment 27, two relevant references are cited. Please see pages 3-4 in the revised\nSupplementary Information as follows:\nLiquid exfoliation process generally involves dispersing bulk materials in a selected\nexfoliating medium and utilizing the energy from ultrasonication to disrupt the Van\nder Waals force between the layers of bulk materials, thus obtaining few-layer 2D\nmaterials. This method does not require harsh chemical treatments or high\ntemperatures, is broadly applicable to various 2D materials, and can potentially be\nscaled up, making it widely adopted [8, 9]. During the exfoliation process, the\nchoice of exfoliating medium plays a crucial role in determining the quality of\nproduct.\nTheoretically, achieving efficient exfoliation is contingent on matching the surface\nenergy of solvent with that of material. This condition minimizes the enthalpy of the\nmixed system, as described by the equation of ΔH /V ≈ 2(δ − δ )2φ/T , where\nmix mix G sol bulk\nΔH, V ,δ, φ, and T represent the enthalpy of mixing, the volume of dispersion,\nmix bulk\nthe square root of component surface energy, the volume fraction of nanosheet, and\nthe average thickness of nanosheet, respectively [8, 9].\n[8] Hernandez, Y. et al. High-yield production of graphene by liquid-phase exfoliation\nof graphite. Nat. Nanotechnol.3, 563-568 (2008).\n[9] Coleman, J. N. et al. Two-dimensional nanosheets produced by liquid exfoliation\nof layered materials. Science.331, 568-571 (2011).\n25. Write other (advantage of the method ultrasonic exfoliation process) in response\n20\nto comment 28.\nResponse: We thank the reviewer for the comment. Regarding the ultrasonic\nexfoliation process mentioned in original Comment 28, we have carefully revisited\nthe two classic references cited in the Supplementary Information (Nat. Nanotechnol,\n2008, 3: 563-568; Science, 2011, 331: 568-571). From these studies, we extract\nseveral advantages of the ultrasonic exfoliation method, including: (i) it does not\nrequire harsh chemical treatments or high temperatures, (ii) it can potentially be\nscaled up, (iii) it is broadly applicable to various layered materials, (iv) it allows\nrelatively simple and rapid preparation. Based on these points, we have revised our\noriginal description to better reflect the advantages of ultrasonic exfoliation. Please\nsee page 3 in the revised Supplementary Information as follows:\nThis method does not require harsh chemical treatments or high temperatures, is\nbroadly applicable to various 2D materials, and can potentially be scaled up, making\nit widely adopted [8, 9].\nReferences for Comment 25\n[1] Hernandez, Y. et al. High-yield production of graphene by liquid-phase exfoliation\nof graphite. Nat. Nanotechnol.3, 563-568 (2008).\n[2] Coleman, J. N. et al. Two-dimensional nanosheets produced by liquid exfoliation\nof layered materials. Science.331, 568-571 (2011).\n26. Please provide 28 references for comment.\nResponse: Thanks for the comment. Revised as suggested. Please see page 3 in\nthe revised Supplementary Information as follows:\nThis method does not require harsh chemical treatments or high temperatures, is\nbroadly applicable to various 2D materials, and can potentially be scaled up, making\nit widely adopted [8, 9].\n[8] Hernandez, Y. et al. High-yield production of graphene by liquid-phase exfoliation\nof graphite. Nat. Nanotechnol.3, 563-568 (2008).\n21\n[9] Coleman, J. N. et al. Two-dimensional nanosheets produced by liquid exfoliation\nof layered materials. Science.331, 568-571 (2011).\n27. In comment 33, do other parameters such as solvent viscosity and polarity also\nhave an effect?\nResponse: We appreciate the reviewer’s comment. Indeed, other solvent\nparameters can also influence the exfoliation process. Taking polarity, as you\nmentioned, as an example, it can affect the interactions between 2D materials and\nexfoliating mediums. As described in Science, 2011, 331: 568-571, the Hansen\nsolubility parameters provide an approach to quantify how exfoliating medium\ninfluences the exfoliation process. These parameters incorporate three contributions to\nthe cohesive energy density: dispersion, polar, and hydrogen-bonding interactions. In\npractice, effective exfoliation of a specific 2D material can only be achieved when all\nthree parameters (dispersion, polar, and hydrogen bond) of the solvent closely match\nthose of the 2D material. As can be seen, polarity is not an independent parameter,\nrather, it is inherently embedded within the Hansen parameter set. That is to say,\nalthough polarity is one of the parameters influencing exfoliation, its effect cannot be\nclearly isolated from other intermolecular interactions, making it methodologically\nchallenging to use polarity as an independent screening criterion. In other words,\nwhile polarity does play a role, it is not appropriate to treat it as a standalone indicator\nfor solvent selection.\nIn contrast, the surface energy is an independent parameter that has been widely\nand successfully used for initial solvent selection. Although other parameters may\ninfluence the exfoliation process, their existence does not undermine the validity of\nusing surface energy as a reliable descriptor, which is well supported by the\nexperimental results in this work. Also, many classical studies have employed surface\nenergy as a guiding parameter to identify suitable exfoliating mediums for various 2D\nmaterials (J. Am. Chem. Soc, 2013, 135: 18-21; ACS Nano, 2016, 10: 2745-2751; Nat.\nNanotechnol, 2008, 3: 563-568). We hope that this clarification addresses your\nconcern.\n[1] Coleman, J. N. et al. Two-dimensional nanosheets produced by liquid exfoliation\nof layered materials. Science.331, 568-571 (2011).\n[2] Zhang, X. et al. Enhanced photoresponsive ultrathin graphitic-phase C N\n3 4\nnanosheets for bioimaging. J. Am. Chem. Soc. 135, 18-21 (2013).\n[3] Han, Q. et al. Atomically thin mesoporous nanomesh of graphitic C N for\n3 4\nhigh-efficiency photocatalytic hydrogen evolution. ACS Nano. 10, 2745-2751 (2016).\n[4] Hernandez, Y. et al. High-yield production of graphene by liquid-phase exfoliation\nof graphite. Nat. Nanotechnol.3, 563-568 (2008).\n28. In comment 42, Explain accumulation of lines further. What does it represent?\nResponse: We appreciate the reviewer’s comment. In our previous response, we\nmay have provided an overly brief explanation. In this round, we offer a more detailed\nclarification regarding your question: “Explain accumulation of lines further. What\ndoes it represent?” In short: “Each curve in Figures 2e and f represents the absorption\nchange between the excited and ground states of the material (0.0PNs/BS or\n0.8PNs/BS) at a specific delay time (0.5, 1, 5, 10 ps......), and plotting multiple curves\non one figure simply visualizes the spectral evolution over time without implying any\n“accumulation” of the signal. A more detailed explanation is provided below.\nFor semiconductor heterojunctions, the key photophysical processes following\nlight excitation include excited-state absorption, ground-state bleaching, and\nstimulated emission. It is worth noting that while all these processes can occur, they\nevolve on different time scales. To facilitate understanding, we give an example: upon\nlight excitation, a molecule can undergo numerous distinct photophysical processes\n(such as fluorescence, phosphorescence, internal conversion, and so on), as depicted\nin the following schematic:\n23\n[Figure Redacted]\nAll these processes may take place within a photo-excited system, but their\ncharacteristic lifetimes differ by several orders of magnitude, ranging from fs-s, as\nshown below:\n[Figure Redacted]\nSimilarly, after light excitation, in semiconductor heterojunctions, processes such\nas excited-state absorption, ground-state bleaching, and stimulated emission also take\nplace on different time scales. To investigate these ultrafast photophysical processes,\nfemtosecond transient absorption spectroscopy, conducted in our study, is a\npowerful technique, as it allows direct tracking of the dynamic evolution of\nthese processes. The configuration of a femtosecond transient absorption\nspectrometer is illustrated as follows:\n[Figure Redacted]\nIn the above figure, the light emitted from the green instrument is used to excite\nthe sample, and after a very short delay (0.5, 1, 5, 10 ps......), a probe beam (from the\nblue instrument) monitors the changes in the sample’s absorption. Femtosecond\ntransient absorption spectroscopy can be understood as an “ultrafast version” of\nUV-vis absorption spectroscopy, recording the evolution of the sample’s absorption\nover time with femtosecond time resolution. However, when directly comparing\nabsorption spectra at, for example, 0.0 ps and 0.5 ps, it is difficult to visually discern\nsignificant differences, as the changes are typically very small. To facilitate\nobservation, the data in femtosecond transient absorption spectroscopy are plotted\nusing ΔA on the vertical axis, where ΔA = A − A , representing the difference\nexcited ground\nbetween the excited-state and ground-state absorption. The sign of ΔA can be used to\nidentify which photophysical process dominates at a given timescale. For instance,\nwhen ΔA < 0, this indicates the occurrence of ground-state bleaching. This is because\nthat, before excitation, most electrons in the semiconductor material reside in the\nground state. Upon light excitation, some of these electrons are promoted to the\nexcited state, reducing the population of ground-state electrons—that is, fewer\nelectrons are available to absorb the probe beam (from the blue instrument). As a\nresult, the measured absorption signal decreases, manifesting as a negative ΔA.\nIn summary, based on the detailed explanation above, we hope it is now clear\nwhat the curves in Figures 2e and f represent: each curve corresponds to the\nabsorption change between the excited-state and ground-state sample (0.0PNs/BS or\n0.8PNs/BS) at a specific delay time (0.5, 1, 5, 10 ps......). Plotting the curves measured\nat different delay times on one figure is simply a way to visually illustrate the spectral\nevolution over time (0.5, 1, 5, 10 ps......), and does not imply any “accumulation” of\nthe signal. We hope this explanation makes it clear.\n29. In comment 43, Sentence (The number of layers of PNs in the heterostructure is\nnot expected to significantly affect the qualitative…), do you have real data or are you\njust expecting it?\nResponse: Thanks for the comment. To be honest, our previous response is based\non a comprehensive review of relevant literature rather than on direct experimental\ndata from our current work. In practice, it is nearly impossible to precisely obtain or\n25\nisolate a dispersion containing phosphorene nanosheets with a single, fixed number of\nlayers. Liquid exfoliation typically produces phosphorene nanosheets within a certain\nlayer-number range, rather than nanosheets with a specific number of layers.\nFor instance, a representative literature (J. Am. Chem. Soc, 2017, 139: 13234-13242)\nstates : “Figure S1 shows the thickness of as-exfoliated BP nanoflakes ranging from\n1.8 to 5.1 nm, which are close to that of the 3~8 phosphorus atomic layers according\nto the monolayer thickness of 0.5-0.7 nm.” Also, Angew. Chem. Int. Ed, 2017, 56:\n10373-10377 reports: “A one-step liquid exfoliation approach followed by\nhigh-speed centrifugation was used to prepare BP nanosheet (BPS, 8-11 nm in\nthickness, 10-14 layers) and FPS (4-5 nm in thickness, 5-6 layers) as confirmed in\nFigures S3a-d and S4a-d, respectively.”\nTherefore, since the exfoliated samples inherently contain phosphorene\nnanosheets with a distribution of layer numbers, it is experimentally unfeasible, with\ncurrent scientific techniques, to systematically investigate the effect of the exact layer\nnumber of phosphorene nanosheets on the experimental results. We hope this\nclarification meets your expectations.\nReferences for Comment 29\n[1] Zhu, M. et al. Metal-free photocatalyst for H evolution in visible to near-infrared\n2\nregion: black phosphorus/graphitic carbon nitride. J. Am. Chem. Soc. 139,\n13234-13242 (2017).\n[2] Ran, J. et al. Phosphorene co-catalyst advancing highly efficient visible-light\nphotocatalytic hydrogen production. Angew. Chem. Int. Ed. 56, 10373-10377 (2017).\n30. In comment 44, Why aren’t curves EIS arc-shaped?\nResponse: Thanks for the comment. We apologize as this is our oversight, and a\nmore detailed description of the experimental procedure may have prevented this\nconcern. We clarify that the EIS measurements reported in our work are performed\nunder dark conditions. In the dark, no photo-generated carriers are present.\nConsequently, the population of mobile carriers available for interfacial charge\n26\ntransfer is limited, which can lead to non-ideal interfacial responses. This kind of\nnon-ideal behavior often makes the Nyquist plot to appear more like a quarter circle\ninstead of a semicircle. In fact, in many reported studies, the EIS measurements are\nalso conducted under dark conditions, and the resulting Nyquist plots similarly exhibit\na quarter-circle shape (Adv. Funct. Mater, 2018, 28: 1705407; Nat. Commun, 2023, 14:\n7115):\n[Figure Redacted]\nFigure R5. EIS Nyquist plots of BP, CN, and 10% BP/CN under dark conditions.\n[Figure Redacted]\nFigure R6. EIS Nyquist plots of BCN, PuCN, and Ni -PuCN under dark conditions.\nSAPs\nBy contrast, under illumination, the generation of abundant photo-generated\ncarriers increases the carrier density and reduces the charge-transfer resistance, so the\nNyquist plots tend to be closer to a semicircle. This dark vs. light distinction has been\nreported both in the literature and our previous work, and is consistent with our\nclarification above (J. Am. Chem. Soc, 2017, 139: 13234-13242; Chem. Eng. J, 2020,\n384: 123258):\n[Figure Redacted]\nFigure R7. EIS Nyquist plots of BP, CN, and BP/CN under dark and light conditions.\n27\n[Figure Redacted]\nFigure R8. EIS Nyquist plots of 6BP/CN under dark and light conditions. Note: In the original\nliterature, the plots for dark and light conditions are presented in separate figures. For your\nconvenience, we have combined the data into a single figure.\nTherefore, the observed EIS shape in our work is consistent with the typical\nsemiconductor behavior under dark conditions. Here we would also like to clarify that\nalthough in some of our earlier studies, EIS measurements are occasionally performed\nunder illumination to obtain more ideal Nyquist plots, in our present work we no\nlonger employ illumination to optimize the EIS data. This is because performing EIS\nmeasurements in the dark enables a direct evaluation of the material’s intrinsic\ninterfacial charge-transfer resistance while avoiding interference from\nphoto-generated carriers. In recent years, our group consistently follows this\nexperimental strategy in all photocatalysis-related studies.\nTo address your concern, we have clearly specified in the Methods section that\nEIS measurements are conducted in the dark. We hope this clarification meets your\nexpectations. Please see page 24 lines 483-486 in the revised manuscript as follows:\nEIS and Mott-Schottky measurements were performed under dark conditions, while\nTPC measurements were conducted under illumination provided by a 300 W Xe lamp\n(PLS-SXE300, Beijing Perfect Light Technology Co., Ltd.). All measurements were\ncarried out at room temperature.\nReferences for Comment 30\n[1] Zheng, Y. et al. Black phosphorus and polymeric carbon nitride heterostructure for\nphotoinduced molecular oxygen activation. Adv. Funct. Mater.28, 1705407 (2018).\n[2] Zhang, X. et al. Developing Ni single-atom sites in carbon nitride for efficient\nphotocatalytic H O production. Nat. Commun. 14, 7115 (2023).\n2 2\n28\n[3] Zhu, M. et al. Metal-free photocatalyst for H evolution in visible to near-infrared\n2\nregion: black phosphorus/graphitic carbon nitride. J. Am. Chem. Soc. 139,\n13234-13242 (2017).\n[4] He, D. et al. Black phosphorus/graphitic carbon nitride: a metal-free photocatalyst\nfor “green” photocatalytic bacterial inactivation under visible light. Chem. Eng. J. 384,\n123258 (2020).\n31. The reference in comment 49 is not valid. Check all sources again.\nResponse: We thank the reviewer for the comment. In our first-round response,\nthe sentence in our original Comment 49 includes a reference: “The reason for this\nstatement is that it reflects the fundamental mechanism of the S-scheme\nheterojunction, which has also been documented in previous studies (Chem, 2020, 6,\n1543-1559).” We understand that the reviewer may have concerns regarding the\ncitation format or completeness. We apologize for the inconvenience caused in the\nfirst-round response, where all references cited in our comments are given in\nabbreviated form, which may have made it difficult for you to assess their validity. To\naddress these, in the current round, all references cited in our responses are provided\nin full immediately following each corresponding comment, including authors, title,\njournal, year, volume, and page numbers. We hope this practice resolves your concern.\nThe full details of the reference cited in our original Comment 49 are given below.\nReferences for Comment 31\n[1] Xu, Q. et al. S-scheme heterojunction photocatalyst. Chem.6, 1543-1559 (2020).\n32. In comment 50, is this sentence (In p-type semiconductors, the majority carriers\nare holes, and the hole density near the valence band is relatively low.) correct?\nResponse: We sincerely apologize for the confusion caused by our oversight. You\nare correct in pointing out the issue in our previous response. The sentence of “In\np-type semiconductors, the majority carriers are holes, and the hole density near the\nvalence band is relatively low.” is indeed incorrect. The issue arises from the word\n29\n“low”. In p-type semiconductors, the hole density near the valence band is actually\nhigh, not low as we mistakenly write.\nWe have carefully checked our revised manuscript. It is found that this sentence\nappears only in our first-round response to your original Comment 50 and does not\nappear in the current main text. Nevertheless, we are very grateful for your careful\nreading and for pointing out this error. We sincerely apologize for this oversight.\n33. Write the synthesis section in the main text.\nResponse: We thank the reviewer for the suggestion. Following your instruction,\nthe synthesis procedures have been incorporated into the main text. Specifically, they\nare integrated into the Methods section, which is placed after the Results and\nDiscussion section, thereby also complying with the editor’s guidance. In the email,\nthe editor specifically suggests: “For Comment 31, the synthesis details may be\nplaced in the Methods section following the Results and Discussion. In your rebuttal\nletter, you may wish to mention to Reviewer #3 that this formatting guidance was\nprovided by the editorial office.” We hope that this practice meets your expectations.\n34. In comment 52, “Has it been tested experimentally or is it only theoretical?”\nResponse: We thank the reviewer for the comment. In your original Comment 52,\nyou ask whether the type of semiconductor affects the design of S-scheme\nheterojunctions. Our statement is that the semiconductor type (n-type or p-type)\ndoes not influence the design of S-scheme heterojunctions. In this review round, you\nfurther ask, “Has it been tested experimentally or is it only theoretical?” We apologize\nfor the lack of clarity in our previous response. Here, we first provide a concise and\ndirect answer: our previous statement has been both experimentally validated and\ntheoretically supported. A more detailed explanation is provided below.\nFirstly, from a theoretical perspective, the construction of an S-scheme\nheterojunction primarily relies on two prerequisites: (i) the two semiconductors must\nhave appropriate band structures to achieve a staggered alignment, and (ii) there\nmust be a sufficiently large Fermi level difference to generate an internal electric field\nthat drives directional charge transfer. These two factors are decisive for establishing the\nare met, combinations of n-n, p-p, p-n, or n-p semiconductors can all form an\nS-scheme heterojunction. The above viewpoint is supported by numerous leading\nstudies. For your convenience, we provide below a relevant figure from a\nrepresentative literature (Adv. Mater, 2022, 34: 2107668):\n[Figure Redacted]\nFigure R9. Four types of S-scheme heterojunctions.\nSecondly, various experimental results have also confirmed our statement.\nExperimental studies show that, in practice, n-n, p-p, p-n, and n-p combinations, can\nform an effective S-scheme charge transfer pathway, provided the two prerequisites\n(as discussed in the above paragraph) are satisfied. For your convenience, we present\nhere some related works published very recently, illustrating the formation of\nS-scheme heterojunctions in n-n (J. Environ. Chem. Eng, 2025, 13: 118625), p-p (Sci.\nRep, 2025, 15: 10789), p-n (Small, 2024, 20: 2306563), and n-p (J. Mater. Sci.\nTechnol, 2024, 170: 200-211) combinations. Based on the discussion above, it can be\nconcluded that our statement has been both experimentally validated and theoretically\nsupported. We hope that our response addresses your concern.\nReferences for Comment 34\n[1] Zhang, L. et al. Emerging S-scheme photocatalyst. Adv. Mater. 34, 2107668\n(2022).\n[2] Nguyen, H. P. et al. Interfacial engineering of ZnSn(OH) /SnO S-scheme\n6 2\nheterojunctions for high-performance solar-light-driven photocatalytic nitric oxide\noxidation. J. Environ. Chem. Eng. 13, 118625 (2025).\n[3] Rezaei, M. M. et al. S-scheme heterojunction of MoO nanobelts and MoS\n3 2\n31\nnanoflowers for photocatalytic degradation. Sci. Rep. 15, 10789 (2025).\n[4] Hu, X. et al. Photoreduction of aqueous protons coupling with alcohol oxidation\non a S-scheme heterojunction photocatalyst MnO/carbon nitride. Small. 20, 2306563\n(2024).\n[5] Zhao, Y. et al. Bi WO /AgInS S-scheme heterojunction: efficient\n2 6 2\nphotodegradation of organic pollutant and toxicity evaluation. J. Mater. Sci. Technol.\n170, 200-211 (2024).\n35. In comment 53, is the difference between 0.5 and 1 due to experimental error?\nWrite another reason.\nResponse: We thank the reviewer for the comment. During the optimization of a\ncertain component’s doping level in a semiconductor photocatalyst, the photocatalytic\nactivity of the catalyst typically exhibits a “rise-and-fall” trend. It is therefore very\ncommon that samples with doping levels below and above the optimal value show\ncomparable photocatalytic activities, a phenomenon that has been widely reported in\nthe literature.\nFor example, in a study by Ran et al., a phosphorene/g-C N heterojunction with\n3 4\n0.6 wt% of phosphorene exhibits a H evolution rate of 139 μmol h−¹ g−¹, while a\n2\nphosphorene/g-C N heterojunction with 9.5 wt% of phosphorene shows a very\n3 4\nsimilar activity of 127 μmol h−¹ g−¹ (Adv. Mater, 2018, 30: 1800128). For your\nconvenience, we have included the relevant figure below, with the red boxes\nhighlighting the two samples that exhibit similar activities despite different\nphosphorene doping levels:\n[Figure Redacted]\nFigure R10. Photocatalytic H -production activities of the samples.\n2\n3 4\nCDots doping levels display nearly identical H evolution activities (Science, 2015,\n2\n347: 970-974). We have included the corresponding figure below, with the blue boxes\nmarking the two samples with similar activities but different CDots doping amounts:\n[Figure Redacted]\nFigure R11. Photocatalytic H -production activities of the samples.\n2\nalso be observed in other photocatalytic reactions, such as H O production, where,\n2 2\nwithin the range below and above the optimal doping level, different samples exhibit\ncomparable photocatalytic activities (Nat. Commun, 2023, 14: 2493):\n[Figure Redacted]\nFigure R12. Photocatalytic H O -production activities of the samples.\n2 2\nAlso, in photocatalytic disinfection reactions, similar trends are often observed.\nFor example, in one study, the photocatalytic disinfection activity of the catalyst\nreaches its maximum when the Bi MoO doping amount is 20 wt% in\n2 6\nBi MoO -g-C N composite. For materials with doping amounts below and above 20\n2 6 3 4\nwt%, the photocatalytic disinfection activities remain very close, which is reflected in\nthe figure by multiple curves highly overlapping (J. Hazard. Mater, 2017, 321:\n183-192). For your convenience, we have included the relevant figure below, with the\nred box highlighting the samples that exhibit similar activities despite different\nBi MoO doping levels:\n2 6\n33\n[Figure Redacted]\nFigure R13. Photocatalytic water disinfection activities of the samples.\nBased on your comment, we have carefully reviewed and summarized the above\nliterature, leading to a reasonable explanation: “when a certain component’s doping\nlevel is below the optimal value, limited interfacial contact restricts photocatalytic\nactivity, while excessive doping leads to overcoverage that suppresses the activity.”\nWe hope this explanation addresses your concern.\nReferences for Comment 35\n[1] Ran, J. et al. Metal-free 2D/2D phosphorene/g-C N Van der Waals heterojunction\n3 4\nfor highly enhanced visible-light photocatalytic H production. Adv. Mater. 30,\n2\n1800128 (2018).\n[2] Liu, J. et al. Metal-free efficient photocatalyst for stable visible water splitting via\na two-electron pathway. Science.347, 970-974 (2015).\n[3] Wang, W. et al. Photothermal-enabled single-atom catalysts for high-efficiency\nhydrogen peroxide photosynthesis from natural seawater. Nat. Commun. 14, 2493\n(2023).\n[4] Li, J. et al. In situ growing Bi MoO on g-C N nanosheets with enhanced\n2 6 3 4\nphotocatalytic hydrogen evolution and disinfection of bacteria under visible light\nirradiation. J. Hazard. Mater.321, 183-192 (2017).\n36. Which active species plays a key role?\nResponse: We thank the reviewer for the comment. Based on our experimental\nresults, •O − plays the most critical role in the photocatalytic disinfection process.\nThe experimental results illustrated in Figure S17 indicate the participation of four\n34\ndistinct ROS for bacterial inactivation, with contributions of •O − > 1O > H O >\n2 2 2 2\n•OH.\n35"}, {"round": 3, "reviewer_comments": {"reviewer_3": "I recommend acceptance of the revised article"}, "author_response": ""}]

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