Substituent-induced oxidation-reduction molecular organic junction for interfacial hydrogen peroxide photosynthesis

Domain: biology
Published: 2026-03-25
Editorial outcome: major_revision

Abstract
The distribution of catalytic active sites critically dictates photocatalytic efficiency, but existing catalyst design operate at the same or adjacent sites still remain limitations toward photocatalytic reaction. To address this, a kind of spatially separable oxidation-reduction assignment in fluorine substituted molecular organic junction catalyst (covalent triazine framework, CTF-TF-0.5) is constructed. By modulating the coordination of F-substituted benzene linkers, we controlled the redox nature of triazine ring in CTFs to obtain the separable oxidation-reduction assignment. It achieves a interfacial hydrogen peroxide (H2O2) photosynthesis rate of 4664 µmol g−1 h−1 at triphasic interface with simulated sunlight and ultrasonic forces. With external forces, the photogenerated-holes allow to transfer to the oxidation site (triazine connected two benzene and a F-substituted benzene) and photogenerated-electrons to the reduction site (triazine connected a benzene and two F-substituted benzene) via benzene bridges for a dual-pathway of water oxidation and oxygen reduction reactions to synthesize H2O2. Additionally, this heterogeneous interfacial reaction system exhibits efficient purification capability for arsenic-containing mining wastewater. This study using the separable oxidation-reduction sites for addressing the coupling reaction at manipulable active sites to improve overall catalytic efficiency via molecular junction catalyst.

Introduction
In heterogeneous catalysis, the nature and arrangement of active sites critically dictate catalyst performance by governing the recognition, activation, and transformation of reactants1–3. Conventional catalyst design typically relies on single-component active sites, such as metal nanoparticles or oxide surfaces, which are highly effective for isolated chemical processes or simple reactions4,5. However, in complex redox reactions, where reactants undergo multiple, sequential oxidation-step sequential oxidation-reduction steps, single active sites always fail to accommodate the diverse mechanistic requirements6. Moreover, their catalytic efficiency is frequently limited by inherent geometric and electronic constraints7,8. In contrast, many natural systems, including photo-synthesis and biodegradation, exploit the cooperative interplay of multiple active sites to achieve efficient, multi-step conversions9,10. Such system provides compelling inspiration for the development of artificial catalysts that harness synergistic interactions with multiple active centers.

The design of artificial catalysts featuring multiple active sites remains a significant challenge due to the minute spatial scale and challenging operability. Conventional strategies, such as heterostructure engineering and metal loading11,12, seek synergy by combining metals, oxides, or organic ligands through simple mixing or bonding. Although these approaches have modestly enhanced catalytic performance, they always suffer from uneven active site distribution and limited control over synergistic interactions13. As catalytic reactions occur at the nanoscale interface between catalyst and reactants, precise control of active sites at the atomic and molecular levels offers a route to achieve the cascade and control of complex redox reactions, driving functional catalytic materials from macroscopic composites toward microscopic manipulation.

Molecular junction catalyst, assembled by molecular structure composed of multiple functional groups, such as oxidative and reductive groups, represents an ideal platform for designing artificial catalysts with multiple active sites14,15. With exceptional design flexibility, it enables precise modulation of catalytic activity, selectivity, and efficiency through tailored adjustments to the redox center and linker chemistry, and their modular architecture allows for optimization across a wider range of reactions, enhancing performance metrics such as turnover frequency and reaction rates16–18. Specifically, designing redox centers at the molecular level enables controlled regulation of active sites, particularly in constructing their spatial distribution (Fig. 1a). This molecular junction catalyst facilitates highly efficient coordination of oxidation and reduction reactions at the molecular level, avoids interference between active sites, and enhances the selectivity and efficiency of complex reactions.

Inspired by these, here we modulated the substituent coordination number of covalent triazine framework (CTF), a representative molecular organic junction, to manipulate the redox properties of adjacent triazine rings, thereby promoting a typical heterogeneous catalytic reaction—hydrogen peroxide (H2O2) interfacial synthesis via oxygen reduction reaction (ORR) and water oxidation reaction (WOR) at independent oxidation and reduction centers. In particular, CTFs and fluorine-substituted CTFs (CTF-TF) were synthesized via a low-temperature approach based on our previous reports19. By precisely modulating the number of different precursors of triazine, benzene, and F-substituted benzene, CTF-1, CTF-TF-0.5, CTF-TF were obtained, and the coordination number of F-substituted benzene linkers to affect the redox nature of the triazine ring in CTFs, thereby presenting separable oxidation-reduction assignment in the conjugated skeleton of CTFs. Based on theoretical calculations, we found that the triazine connected a benzene and two F-substituted benzene exhibits as reduction site, while the triazine connected two benzene and a F-substituted benzene exhibits as oxidation site (Fig. 1b). With a gradual increase in the number of F substitutions in CTFs, only CTF-TF-0.5 exhibits a clear separation of oxidation-reduction assignment, relative to CTF-1 and CTF-TF (Fig. 1c). Under external forces, the photogenerated-holes allow to transfer to the oxidation site and photogenerated-electrons to the reduction site via benzene ring bridges. Then, O2 and H2O are adsorbed at the N active sites of triazine connected a benzene and two F-substituted benzene and triazine connected two benzene and a F-substituted benzene in CTF-TF-0.5 for H2O2 synthesis at the gas-liquid-solid triphasic interface. This separable oxidation-reduction assignment in the molecular junction catalyst enables the cascade and control of complex redox reactions at the molecular level, and provides opportunities for designing functional artificial catalysts with multiple active sites.

Results
Spatial distribution of oxidation-reduction sites in CTFs
We began to explore the spatial distribution of oxidation-reduction sites of all CTFs by using density functional theory (DFT) simulations. For catalytic reactions, the energy band positions of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) determine the oxidation and reduction capacities, and their spatial distribution determines the distribution of oxidation-reduction site on the catalyst molecular20. As shown in Fig. 2a, CTF-TF-0.5 exhibited a clear separated spatial distribution of HOMO and LUMO. Specially, its HOMO is localized at the triazine connected two benzene and a F-substituted benzene (N1), while LUMO is localized at the triazine connected a benzene and two F-substituted benzene (N2). In contrast, both CTF-1 and CTF-TF showed irregular and overlapping spatial distributions of LUMO and HOMO. This difference in HOMO-LUMO spatial distribution indicated that CTF-TF-0.5 showed a clear spatial distribution of oxidation-reduction assignment due to the modulation of F-substituted number, which is further confirmed through electron-hole distribution simulation with time-dependent DFT calculations (Fig. S1).

To further verify the feasibility of H2O2 photosynthesis in CTFs with different oxidation and reduction sites, the projected density of states (PDOS) was carried out in Fig. S2. Compared to CTF-1 and CTF-TF, the PDOS of the VB and CB edge (HOMO and LUMO) in CTF-TF-0.5 simultaneously present more nitrogen orbital contributions, suggesting that the VB and CB in CTF-TF-0.5 mainly originate from N on the triazine ring and trace amounts of C. Furthermore, to distinctly distinguish the contributions of N1 and N2 on the triazine ring for HOMO and LUMO, a single CTF-TF-0.5 single unit was selected for PDOS analysis. As shown in Fig. S3, the N1 2p orbital contributed the more HOMO, while the N2 2p orbital contributed the more LUMO. This also help confirm that N1 and N2 in CTF-TF-0.5 serve as oxidation and reduction sites, respectively. Furthermore, we also investigated the thermodynamics of the WOR and ORR to produce H2O2 at all sites on CTF-1, CTF-TF-0.5, and CTF-TF by analyzing Gibbs free energy (ΔG) and intermediate configurations (Figs. 2b and S4–S11). The results revealed that CTF-TF-0.5_N2 exhibited the lowest free energy for ORR to H2O2, accompanied by a sequential transition of reactive oxygen intermediates (*O2− to *OOH), followed by proton coupling to form H2O2. Meanwhile, CTF-TF-0.5_N1 showed the lowest free energy for WOR to H2O2, with a reactive oxygen intermediate (*OH), which then two *OH combines to produce H2O2. These confirmed that the N1 site of CTF-TF-0.5 serves as the oxidation center for WOR, while the N2 site acts as the reduction center for ORR. Moreover, CTF-TF-0.5 facilitates more efficient bulk charge separation of photogenerated carriers into distinct molecular units, enhancing H2O2 overall photosynthesis compared to CTF-1 and CTF-TF.

Structural characterization
CTF-1, CTF-TF-0.5, and CTF-TF were synthesized via direct cyclotrimerization of aromatic aldehydes using NH4I (Fig. S12)19. The resulting nanosheet-like morphologies were confirmed by scanning electron microscopy and transmission electron microscopy (Figs. S13 and S14). The X-ray diffraction pattern of CTF-1 revealed two diffraction peaks at 7.5° and 18.2°, corresponding to the (100) and (210) planes, respectively, indicating a moderate degree of crystallinity, while that of CTF-TF-0.5 and CTF-TF exhibited no obvious diffraction peaks, showing that both of them are amorphous (Fig. S15)19. The pore structures and surface areas of CTFs were characterized by N2 adsorption-desorption measurements (Fig. S16). All samples displayed significant nitrogen adsorption in the low-pressure region (P/P0 < 0.1), and the Brunauer–Emmett–Teller surface areas of CTF-1, CTF-TF-0.5, and CTF-TF were determined to be 301, 426, and 385 m2 g−1, respectively.

The chemical environment and structural integrity were explored using solid-state NMR (13C, 1H, and 19F) spectroscopy. In the CP-MAS 13C-NMR spectrum (Fig. 3a), the CTF-1 demonstrates the obvious carbon signals from the triazine units at 170.4 ppm (a) and the phenyl carbons (b and c) at 138.8 ppm and 128.7 ppm. In the CTF-TF, the carbon signal of triazine rings shifts to 159 ppm because of the introduction of fluorine atoms (a’), and the carbon signal of fluorinated benzene rings are located at 145.1 ppm (c’). Moreover, the carbon atoms connected with triazine rings display a peak at 119 ppm (b’). Note that the CTF-TF-0.5 simultaneously displayed the carbon signals (a and a’) from the triazine units without and with fluorine atoms and the phenyl carbons (b and c), and the carbon signal (c’) of fluorinated benzene rings, and the carbon atoms connected with triazine rings (b’), which indicated that CTF-TF-0.5 contains both benzene ring and fluorine-substituted benzene ring19. The solid-state 1H NMR spectra of CTF-1 and CTF-TF-0.5 exhibit a signal at approximately 7.5 ppm, originating from H atom on the benzene ring (Fig. S17a), while the solid-state 19F NMR spectra of CTF-TF-0.5 and CTF-TF exhibit a signal at approximately −144 ppm, originating from F atom on fluorine-substituted benzene ring (Fig. S17b).

The chemical bonding characteristics of CTF-1, CTF-TF-0.5, and CTF-TF were investigated using Fourier transform infrared spectroscopy (FT-IR) (Fig. 3b). All samples exhibited two characteristic vibration signals associated with triazine units, appearing in the range of 1300–1600 cm−1. For CTF-1, sharp peaks at 1356 and 1510 cm−1 corresponded to triazine unit vibrations, while the peak at 813 cm−1 is attributed to benzene rings. Similarly, CTF-TF-0.5 and CTF-TF displayed peaks at about 1356 and 1515 cm−1, indicative of triazine units, along with an additional peak at 983 cm−1, assigned to the stretching vibrations of C−F bonds21, confirming the formation of CTF-TF and CTF-TF-0.5. Meanwhile, as the number of F substituents increases, the peak at 813 cm−1 gradually decreases, indicating that the benzene ring is progressively substituted by F as the amount of F substitution increases. These results revealed the successful synthesis of CTF-TF-0.5 with our previous report19, which was further corroborated by simulated FT-IR spectra with using Gauss (Figs. 18 and S19) and X-ray photoelectron spectroscopy analyses (Figs. S20–23 and Table S1).

The optical absorption properties of the samples were investigated using UV–visible diffuse reflectance spectroscopy. All samples exhibited an absorption edge around 600 nm (Fig. S24). As the F content increased, the yellow color of CTF gradually deepened, and the light absorption range broadened. This enhancement is attributed to extended electron delocalization and increased n–π* electronic transitions22,23. Electron paramagnetic resonance (EPR) spectroscopy was employed to probe the presence of unpaired electrons (Fig. 3c). CTF-TF-0.5 exhibited the strongest single Lorentzian signal at g=2.005, indicative of delocalized electrons on the triazine ring24,25. This is likely due to the enhanced asymmetry introduced by the F-substituted benzene in CTF-TF-0.5, which strengthens the electronic delocalization on the triazine ring.

Charge behaviors promoted by F substituent coordination
By tuning the number of F substitutions on CTFs, distinct spatial distributions of oxidation-reduction sites were achieved to enhance the piezoelectric effect. To further explore the modulation of surface charges, Kelvin probe force microscopy was employed to map the surface piezoelectric potential distribution of all samples (Figs. S25 and S26). The contact potential difference (VCPD) of CTF-TF-0.5 ranged from −51 to −14 mV, significantly lower than that of CTF-1 (3.07 to 17.2 mV) and CTF-TF (−18 to 0.82 mV). Additionally, VCPD values were calculated using the following equation26:
VCPD = φtip − φsample / e (1)
where φtip and φsample represent the work functions of the probe and the sample, respectively, and e represents the electron charge. Through this relationship, we found that CTF-TF-0.5 exhibited a higher work function than CTF-1 and CTF-TF, which indicated that electrons don’t escape easily without light27. Moreover, under illumination, CTF-TF-0.5 demonstrated an average surface potential enhancement of approximately 57 mV, while those of CTF-1 and CTF-TF showed almost no change under light. This enhancement is attributed to the spatially separated oxidation-reduction sites of CTF-TF-0.5, which allow for photogenerated electrons to escape from the surface, significantly boosting surface potential.

The piezoelectric properties of all samples were further evaluated using piezoresponse force microscopy. The phase-voltage hysteresis loop for all CTFs (blue line, Fig. 3d–f) displayed a clear hysteresis with a 180° phase shift at 5 V, indicating distinct local polarization switching behavior28. Moreover, the amplitude-voltage butterfly loop for CTF-TF-0.5 exhibited a remarkable amplitude of approximately 4.74 nm, significantly surpassing the 0.495 nm of CTF-1 and 0.733 nm of CTF-TF (red line), demonstrating the superior piezoelectric performance of CTF-TF-0.5. These results strongly confirmed that the spatial distribution of oxidation-reduction assignment in CTFs plays a crucial role in enhancing the local piezoelectric properties of CTF-TF-0.5.

Charge migration behavior with separated oxidation-reduction assignment
As previously noted, CTF-TF-0.5 exhibits separated redox assignments resulting from the modulation of F substitution on the benzene ring, which significantly promotes directed bulk electron-hole separation within the catalyst. Moreover, structural reorganization of piezoelectric materials under external force leads to an enhanced local dipole moment, further facilitating carrier migration29. To probe the structural changes under high pressure, in-situ FT-IR spectroscopy was employed on all CTFs (Fig. 4a–c). As pressure increased, the characteristic peaks of the triazine ring exhibited a gradual blue shift. At approximately 15 GPa, the triazine ring peaks in CTF-1 shifted from 1357 cm−1 and 1519 cm−1 to 1420 cm−1 and 1567 cm−1, respectively, while the benzene ring peaks at 811 cm−1 remained nearly unchanged. Upon incorporating F substitution, the triazine ring peaks in CTF-TF-0.5 shifted from 1356 cm−1 and 1504 cm−1 to 1421 cm−1 and 1566 cm−1, whereas CTF-TF exhibited a shift from 1501 cm−1 to 1554 cm−1. The C-F peaks of both CTF-TF-0.5 and CTF-TF also displayed a slight blue shift under pressure (Fig. 4b). The calculated blue-shift rates for the triazine rings (triazine-1 and triazine-2) were 3.26 and 3.34 cm−1 GPa−1 in CTF-1, 3.73 and 3.68 cm−1 GPa−1 in CTF-TF-0.5, and 3.38 cm−1 GPa−1 (triazine-2) in CTF-TF. For C-F, the blue-shift rates were 1.21 cm−1 GPa−1 in CTF-TF-0.5 and 1.29 cm−1 GPa−1 in CTF-TF (Fig. 4c). The more pronounced blue-shift rates observed in CTF-TF suggest shorter bond length changes during structural reorganization under pressure, which serve to enhance the local dipole moment (Fig. 4d)30. These variations in blue-shift magnitudes underscore the distinct mechanical responsiveness of the samples and demonstrate that the separated oxidation-reduction sites in CTF-TF-0.5 significantly enhanced its piezoelectric properties under pressure.

Compared to CTF-1 and CTF-TF, the enhanced performance of CTF-TF-0.5 for H2O2 production suggests that rapid electron migration occurs during the photocatalytic process. To explore the charge migration behavior, the fundamental energy band structures of all samples were determined using Tauc plots and Mott-Schottky plots (Figs. S27–29). Additionally, in-situ pressure-dependent UV‒vis absorption spectra were measured to examine the force-induced shifts in the absorption edges of all CTFs. As shown in Figs. 4e and S30–32, with increasing pressure from 0 to 15 GPa, the absorption edges of all samples exhibited significant redshifts, with the color of the samples gradually transitioning from yellow to brown. The band gap of CTF-1 decreased from 2.20 to 1.73 eV, CTF-TF-0.5 from 2.16 to 1.84 eV, and CTF-TF from 2.12 to 1.74 eV (Figs. S33 and S34). Upon releasing the pressure to 0 GPa, the bandgaps of CTF-1, CTF-TF-0.5, and CTF-TF increased to 2.18, 2.15, and 2.03 eV, respectively (Fig. 4f). These observations indicated that pressure application effectively modulates the local energy bands, enhancing the migration and transport of photocatalytic charge carriers.

To understand the charge carrier behavior in CTF-TF-0.5 with separated oxidation-reduction site, the solid-state photoluminescence (PL) spectra were analyzed. As shown in Fig. S35, CTF-TF-0.5 exhibited a lower PL intensity than other samples with a quenching efficiency of 88.8% relative to CTF-1 and that of 87.8% relative to CTF-TF. These results suggested that the separated oxidation-reduction site in CTF-TF-0.5 effectively suppress photogenerated charge recombination. The peak position of PL emission peak displayed slight red-shifted, perhaps due to the narrowing of energy band after adding F substitution. The charge carrier migration properties were further explored through electrochemical techniques, including transient photocurrent, electrochemical impedance spectroscopy, and linear sweep voltammetry (Figs. S36–S38).

To investigate the charge migration process in photoexcited CTFs under an external force, in-situ pressure-dependent PL spectroscopy was conducted. With pressure increased from ambient to 15 GPa, all CTFs exhibited a color change from yellowish to colorless (Figs. S39–41). As shown in Figs. 4g, h and S42, the PL peak positions of all samples exhibited a noticeable redshift with increasing pressure, while the PL intensity of CTF-TF-0.5 was significantly lower than those of CTF-1 and CTF-TF. Notably, the decrease rate of intensity in CTF-TF-0.5 was more pronounced than in the other samples. Upon pressure release to 0 GPa, the peak position reverted, though the peak intensity remained diminished, suggesting that structural damage under applied pressure weakened the material’s luminescence31. The exciton binding energy (Eb), determined from temperature-dependent PL spectra, and the emission peak intensities from steady-state PL spectra followed the order: CTF-1 > CTF-TF > CTF-TF-0.5 (Figs. S43–S45). This indicated that exciton dissociation is most efficient in CTF-TF-0.5, followed by CTF-TF and CTF-1. These all findings confirm that external pressure enhances charge separation efficiency in photoexcited CTFs, along with CTF-TF-0.5 exhibiting the highest charge separation efficiency. Therefore, this separated oxidation-reduction assignment could improve efficiently charge migration behavior.

Heterogeneous interfacial H2O2 photosynthesis pathway via separated oxidation-reduction assignment
To explore the role of the separated oxidation-reduction site in H2O2 photosynthesis, CTF-1, CTF-TF-0.5, and CTF-TF were tested in a reactor under both ultrasonic (Us) force and simulated sunlight (Fig. 5a). As shown in Figs. 5b, S46, and S47, the photocatalytic performance of CTF-1, CTF-TF-0.5, and CTF-TF in various scenarios after 60 min followed the order: CTF-TF-0.5/Us/light > CTF-1/Us/light > CTF-0.5/light > CTF-TF/Us/light > CTF-TF/light > CTF-TF-0.5/Us > CTF-1/light > CTF-1/Us > CTF-TF/Us. Notably, the H2O2 yield of CTF-TF-0.5 showed only a slight increase relative to CTF-TF and CTF-1 under Us or light alone. However, when both Us and light are applied simultaneously, the H2O2 yield of CTF-TF-0.5 (3.28 mmol g−1 h−1) was 2.43 times higher than with light alone, 4.75 times higher than with Us alone, and 2.13 and 2.69 times higher than the yields from CTF-1 and CTF-TF under Us and light, respectively. In addition, the mass transfer of reactants to the surface of photocatalyst is also an important factor affecting the reaction efficiency, which will be studied in our subsequent research. Note that the H2O2 yield is governed by both the formation rate (kf) and the decomposition rate (kd), and the reaction kinetics can be described by the equation [H2O2] = (kf/kd) {1-exp(-kd t)}, where kf and kd are derived from zero-order and first-order kinetics (Figs. S48 and S49)32. These analyses demonstrated that CTF-TF-0.5/Us/light exhibits the highest kf, suggesting that this condition leads to the highest H2O2 yield compared to other conditions (Fig. S50). The apparent quantum yield (AQY) of CTF-TF-0.5 was calculated at specific wavelengths and shown to approximately match the UV–Vis spectrum (Fig. S51), which demonstrated the excellent AQY at 420 nm compared to the reported catalysts (Table S2). Special attention need to be paid to the fact that the current yield shows a high value among most of the reported COF-based photocatalysts and piezocatalysts and is even higher than that of most piezo-photocatalysts (Table S3).

It is worth noting that CTF-TF-0.5 floated on the surface of water to react during the photosynthesis, which was very favorable for direct sunlight irradiation and direct mass transfer of O2 from the gas to catalyst without passing through water (Fig. 5a). To identify the role of gas-solid-liquid triphase in H2O2 production, the photocatalytic performance of CTF-TF-0.5 in three-phase and two-phase systems were investigated (Figs. 5c, S52, and S53). By using cyclohexane, a liquid with a density lower than that of CTFs and water, to covering CTF-TF-0.5 to prevent transfer mass of O2 from air to catalyst, the H2O2 photosynthesis performance of diphase rapidly decreased by about 64.5% relative to that of triphase. Water contact angles were further used to explore the interface state of triphasic system using CTF-1, CTF-TF-0.5, and CTF-TF (Fig. S54). With the increase of F content, contact angel of CTF-TF-0.5 and CTF-TF increased by ~20°, relative to that of CTF-1. This suggests that the increase of F contents significantly enhance the hydrophobicity of CTFs, which is more favorable to the formation of three-phase interfaces. These indicated that the floating CTF-TF-0.5 via separated oxidation-reduction assignment effectively enhanced H2O2 photosynthesis.

Widespread practical application of piezo-photocatalysts requires several factors, including the solar-to-chemical conversion (SCC) efficiency, stability, and suitability in various media. The photocatalytic H2O2 production using the AM-1.5G filter with Us was carried out and the SCC efficiency of CTF-TF-0.5 with mechanical force was also calculated to 0.16% (Fig. S55 and Table S4), surpassing the typical photosynthetic efficiency of plants of 0.10%33, which demonstrated the excellent SCC compared to the reported catalysts (Table S5). Moreover, H2O2 production over CTF-TF-0.5 for a wide pH range (pH=1~11) were also explored (Fig. S56), and the optimum pH is 3. CTF-TF-0.5 exhibited good stability over 6 h, and then it gradually decreased and eventually stabilized at 10 h with about 24 mmol g−1 (Figs. 5d and S57). Furthermore, the H2O2 production rate in various water samples was examined. As shown in Fig. 5e, the H2O2 yield from CTF-TF-0.5 consistently exceeded 1.6 mmol g−1 h−1 across the different real water samples, despite slightly lower performance than pure water due to the impact of a large number of ions or organics in the real water on H2O2 production. These results underscored the practical potential of CTF-TF-0.5 as an effective catalyst for H2O2 photosynthesis, making it a promising candidate for environmental application.

Heterogeneous interfacial H2O2 photosynthesis pathway via CTF-TF-0.5
The intrinsic electronic structure of CTFs plays a pivotal role in determining catalytic activity and provides insights into the microscopic processes at the catalytic active sites. To elucidate the localized electron distribution profiles, the electron localization function was computed. As shown in Fig. S58, the electron cloud distribution in CTF-1 and CTF-TF exhibited symmetric spatial patterns, while CTF-TF-0.5 displayed an asymmetric distribution, attributed to its separated oxidation-reduction sites. Upon applying pressure, all CTFs showed a similar trend of slightly increased electron cloud density (Fig. S58). The strong charge interactions between adsorbed O2 and nitrogen atoms in the CTFs were further explored through charge density difference (Figs. S59 and S60). In the case of F-substituted CTFs, electron accumulation on O atoms and depletion at the N edges became more pronounced under applied pressure, confirming the activating influence of F substitution. Notably, CTF-TF-0.5 and CTF-TF exhibited higher electron transfer and adsorption energies under pressure. These findings highlighted that the separated oxidation-reduction sites in CTF-TF-0.5 enhance electron activity and O2 activation, thereby boosting catalytic performance, and O2 adsorption capacity of CTF-TF-0.5 was demonstrated through O2 temperature-programmed desorption (Fig. S61).

As demonstrated in Fig. 2b, CTF-TF-0.5 exhibits a higher propensity for H2O2 production via both ORR and WOR compared to CTF-1 and CTF-TF. To further elucidate the reaction pathways, H2O2 production was investigated under varying O2/N2 atmospheres. As shown in Fig. S62, the H2O2 production rate was significantly higher in an O2 atmosphere than in air, while production in N2 was markedly lower, remaining at approximately 1.3 mmol g−1. The outstanding 2e− ORR of CTF-TF-0.5 for H2O2 production with high selectivity (~85%) was further evaluated by rotating ring-disk electrode analysis (Fig. S63)34. Various sacrificial agents experiment revealed that *O2− predominantly contribute to H2O2 production, whereas *OH play a lesser role (Fig. S64). The generation of *O2− and *OH was further corroborated by EPR spectroscopy (Figs. S65 and S66). Isotopic labeling experiments provided additional insights into the reaction pathways (Table S6). In a system with H216O and 18O2, the 18O signal in the produced H2O2 under light irradiation was significantly higher than that without light, confirming the contribution of ORR35. Similarly, in a system with H218O and 16O2, the presence of 18O signals in the produced H2O2 under light further confirmed the contribution of WOR. These results provide compelling evidence that CTF-TF-0.5 achieves efficient H2O2 production through a dual-pathway mechanism leveraging both ORR and WOR in our catalytic system36,37. The H2O2 production via WOR pathway was also been proved through isotope experiments using Gas chromatography-mass spectrometry (Fig. S67).

To investigate the intermediates involved in photocatalytic H2O2 production using CTF-TF-0.5 under Us, in-situ EPR experiments were performed (Figs. S68 and 5f, g) to understand the dynamic reaction processes. DMPO was employed to capture the in-situ generated *O2−, *OOH, and *OH intermediates. For the ORR intermediates (Fig. 5f), the *O2− signal emerged at 72 s under Us and light, increasing steadily until approximately 216 s, with a peak concentration of 1.63 × 10−4 M. Subsequently, *O2− was rapidly converted to *OOH by protonation and continues to grow to 376 s, with optimum concentration of 3.07 × 10−4 M, and it also maintained to 600 s. For the WOR intermediates (Fig. 5g), the *OH signal appeared at 123 s, progressively increasing and stabilizing within the range of 1.52 × 10−5 to 3.24 × 10−5 M by 600 s. These findings indicated that H2O2 production occurs through a combination of an indirect 2e− ORR and a 1e− WOR process. The full EPR spectra with a sweep time of 4 s per sample were provided in Figs. S69 and S70 for detailed analysis. Figure S71 illustrates the simulated EPR spectra of *O2−, *OOH, and *OH.

According to the findings of this study, we proposed a mechanism for separated oxidation-reduction site in F-substituted CTFs to promote H2O2 overall photosynthesis (Fig. 5h). Initially, due to F substitutions in CTFs, a separated oxidation-reduction site is formed in the CTFs-TF-0.5 plane. Under Us/light conditions, this separated oxidation-reduction center allows the photogenerated electrons and holes to undergo directional migration. Then, the O2 is easily adsorbed on the surface of N2 atoms and the adequate electrons localized at N2 reduces O2 to undergo ORR through an indirect 2e− transfer pathway with intermediates of *O2− and *OOH to form H2O2. Meanwhile, the positive holes localized at N1 oxidized H2O to form *OH, which subsequently combined to produce H2O2 through 1e− WOR.

Evaluation of the environmental applications of heterogeneous interfacial H2O2 photosynthesis system
It is well known that arsenic (As)-containing wastewater from acid mine drainage and metallurgical industries remain a huge challenge for water pollution control due to its biotoxicity and bioaccumulation38. Here, we used CTF-TF-0.5 with separated oxidation-reduction sites for acidic wastewater containing As(III) purification. As shown in Figs. 6a and S72a, CTF-TF-0.5 showed the highest oxidation capacity of As (III) (63.5%) relative to CTF-1 (26.8%) and CTF-TF (40.6%), while the concentration of As(V) of all CTFs gradually increased. During the degradation, the production of H2O2 also shows a positive correlation with its oxidation rate of As(III) (Fig. S72b, c). Interestingly, the adsorption of As(V) in CTF-TF-0.5 was significantly higher than those of CTF-1 and CTF-TF, which was attributed to the excellent adsorption capacity of CTF-0.5 for As (V) (Fig. S72d). Furthermore, the As (III) oxidation of CTF-TF-0.5 was extended to a long time reaction (Fig. 6b). The concentration of As(III) was oxidized by about 95.7% within 3 h, while the concentration of As(V) was about 806 mg L−1. During 3 h reaction, it also exhibits a continuously increasing H2O2 concentration, reaching 244.5 μM at 3 h (Fig. S73). The effect of different pH on As oxidation was also evaluated in the Fig. 6c, the concentration of As(III) was completely oxidized within 90 min at pH=3 and displayed a highest oxidation rate of 0.0527 min−1 than those at pH=7 and pH=10 (Fig. S74a). During 3 h reaction, it also exhibits a continuously increasing H2O2 concentration at pH=3, reaching 471.5 μM at 3 h, which was significantly higher than that at pH=7 and pH=10 (Fig. S74b, c). The adsorption of As (V) in CTF-TF-0.5 at pH=3 was significantly higher than those at pH=7 and pH=10, which was due to the adsorption of As (V) could be promoted under acid condition (Fig. S74d). The effect of initial concentration of As(III) oxidation and the in-situ generation of H2O2 was also explored (Figs. S75 and S76). Furthermore, scavengers were added to the initial solution to investigate the reaction mechanism of photocatalytic As(III) oxidation with Us. TBA for *OH have no effect on As(III) oxidation, while p-BQ for *O2− have some effect for that. Note that catalase for H2O2 mainly contribute to As(III) oxidation, due to that the addition of catalase resulted in its near total loss of oxidation capacity (Fig. S77). These results demonstrate that As(III) oxidation via piezo-photocatalysis was directly utilized for the oxidation of As(III), without conversion into other reactive species.

It is worth that the pH of acidic As-containing wastewater from mine drainage always ranges from 2.0 to 3.539. Thus, our proposed catalytic system was also used to treat real As-containing acidic mine wastewater with pH=2.8 (Fig. 6d). First, CTF-TF-0.5 did not exhibit significant adsorption under natural conditions for 20 min. With the reaction beginning, about 34 μg L−1 As(III) was completely oxidized within 3 h, and about 6 μg L−1 of As(V) at initial solution and As(V) converted via As(III) was completely adsorbed within 30 min. These results fully demonstrated the application potential of CTF-TF-0.5 with separated oxidation-reduction site in real As-containing acidic mine wastewater. It is also expected to be a key component for mine wastewater treatment in the future (Fig. S78).

Methods
The material, instruments, other experiments and characterizations are discussed in Supplementary Information (Texts S1–S8).

H2O2 photosynthesis at a triphasic interface
Five milligram catalyst was added in 40 mL pure water and the suspension was dispersed by ultrasonication. The reactor was maintained at 25 ± 0.5 °C using a cooling circulating water system and irradiated with full-spectrum light from a 300 W Xe lamp (PLS-SXE300D, Beijing Perfectlight Technology Co., Ltd) at an intensity of 150 mW cm−2. Simultaneously, the suspension was subjected to react using an ultrasonic cleaner (40 kHz, 100 W, Jielimei, Kunshan, China). For light-only control experiments, the reactor was placed under the Xe lamp with stirring. The concentration of H2O2 was determined using the KI colorimetric method40. One milliliter of freshly prepared KI reagent A (0.4 M KI, 0.05 M NaOH, 1.6 × 10−4 M (NH4)6Mo7O24·4H2O) and 1 mL reagent B (0.1 M KHC8H4O4) were mixed with 1 mL the above samples. The absorbance of the above mixture was measured at 350 nm by a UV‒Vis spectrophotometer (JASCO V-770, Japan).

In-situ high-pressure FT-IR, UV–Vis absorption, and PL spectra
High-pressure experiments were conducted using a symmetric diamond anvil cell equipped with ultra-low fluorescence diamond anvils featuring a culet diameter of 400 µm. A T301 stainless steel gasket was pre-indented to a thickness of 45 µm and laser-drilled to create a 150 µm diameter sample chamber, which housed both the sample and a ruby ball for pressure calibration. The pressure was determined using the ruby fluorescence technique by monitoring the shift of the R1 line of ruby fluorescence. Silicon oil was employed as the pressure-transmitting medium to ensure hydrostatic conditions41. All high-pressure experiments were performed at room temperature.

High-pressure PL measurements were conducted using a custom-built optical measurement system. The pressure-dependent PL spectra were obtained with a semiconductor laser at an excitation wavelength of 355 nm. To ensure consistency, parameters such as laser intensity and luminous flux were fixed during each high-pressure PL experiment, minimizing potential variations in PL intensity for CTFs. Absorption spectra were recorded in the exciton absorption band region using a deuterium-halogen light source. Both high-pressure PL and absorption spectra of CTFs were acquired using an Ocean Optics QE65000 optical fiber spectrometer. For in situ high-pressure infrared (IR) experiments, KBr was employed as the pressure-transmitting medium. IR spectroscopy of TriPE was performed using a Nicolet iN10 microscope spectrometer (ThermoFisher Scientific, USA) equipped with a liquid nitrogen-cooled detector41.

Arsenic containing acid mine wastewater treatment
Before the start of the experiment, As (III) standard solution (1000 mg L−1) was diluted stepwise into 1 mg L−1 As(III) solution. 1 mg CTFs was added to 40 mL As(III) solution (1 mg L−1) to form the reaction system. A mechanical stirrer was used for 20 min to stabilize the adsorption, then the reactor was kept at 25 ± 0.5 °C with cooling circulating water and was illuminated using the Xe lamp with a light intensity of 150 mW cm−2, and simultaneously subjected to ultrasonication by the ultrasonic cleaner without stirring. The pH was adjusted with 1 M HCl and NaOH to perform pH experiments. For acidic As-containing mining wastewater treatment, 40 mL wastewater was filtered to conduct the same experimental procedure. The concentration of As(III) and As(V) was determined by HPLC-AFS. With the instrument beginning, it was step-by-step cleaned with 30% methanol-water and the configured mobile phase (1.98 g (NH4)2HPO4 was dissolved in 1 L pure water, and then formic acid and ammonia was used to adjust the pH to 6 with ultrasound for 30 min) for 20 min. In addition, 3% potassium borohydride-5‰ sodium hydroxide solution was prepared as the reducing agent, and the gas was opened for 30 min. 5% HCl was used as the carrier solution.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "The authors constructed a covalent triazine framework (CTF)-based catalysts featuring spatially separated oxidation and\nreduction centers. These catalysts exhibit exceptional performance in the photocatalytic synthesis of H2O2 and facilitate the\ndirect oxidation of As3+ to As5+ using in-situ generated H2O2. However, several aspects require further attention:\n(1) Although the introduction outlines the design concept of spatially separated redox centers and identifies the\ncorresponding molecular structures, direct evidence confirming their respective roles as oxidation and reduction sites is\nlacking. Additional experimental or characterization data are necessary to substantiate this claim.\n(2) The reported H2O2 production activity was measured under simulated sunlight using a full-spectrum xenon lamp at 150\nmW·cm-2 without an AM 1.5G filter. To accurately reflect solar conditions, performance should be evaluated under standard\nAM 1.5G irradiation, and the solar-to-chemical conversion (SCC) efficiency should be calculated to enable comparison with\nother catalytic systems.\n(3) Given the light absorption of catalysts up to 600 nm, measuring the apparent quantum yield (AQY) at specific\nwavelengths across the 360-600 nm range is recommended. Comparative AQY values against established high-\nperformance catalysts would strengthen the performance assessment.\n(4) While the catalyst demonstrates high H2O2 production activity, direct comparative data with existing systems are not\nprovided. Inclusion of such comparisons would better contextualize its performance and highlight any competitive\nadvantages.\n(5) Although multiple characterization techniques were employed to verify the catalyst structure, solid-state NMR (13C, 1H,\nand 19F) spectroscopy could provide further insight into the chemical environment and structural integrity.\n(6) The authors suggest that the catalyst can adsorb O2 from air (Figure 4a). O2-temperature-programmed desorption (O2-\nTPD) experiments are recommended to quantitatively assess O2 adsorption capacity and offer more direct evidence.\n(7) Figure 4c indicates a high H2O2 production rate over 6 hours, with an approximately linear increase and no sign of\nplateau. Extending the reaction duration would help determine the maximum H2O2 yield, while post-reaction\ncharacterization of the catalyst would aid in evaluating its stability.\n(8) Although isotope labeling experiments confirm the H2O oxidation pathway for H2O2 formation, rotating ring-disk\nelectrode (RRDE) measurements are advised to determine the electron transfer number and H2O2 selectivity for the O2\nreduction pathway, thereby offering more comprehensive mechanistic insight.\n(9) The authors propose that H2O2 generation proceeds via indirect pathways involving radicals such as •OH or •O2-.\nScavenging experiments are recommended to further validate the contributions of these active species.\n(10) While the effect of pH on As3+ oxidation was examined, the influence of pH on the photocatalytic generation of H2O2\nshould also be investigated to fully assess the applicability of catalysts across varying reaction conditions.", "reviewer_2": "I have read the manuscript titled “Substituent coordination inducing oxidation-reduction molecular organic junction to boost\nheterogeneous interfacial hydrogen peroxide generation” by Li et al. with interest. The work addresses the construction of\nmolecular organic frameworks with spatially separated redox centers to enhance photocatalytic H₂O₂ generation and arsenic\nremoval. While the topic is relevant and potentially impactful, the manuscript suffers from conceptual, structural, and\nanalytical weaknesses that currently preclude publication in its present form. I recommend rejection at this stage, with the\npossibility of resubmission after major revision and significant additional experimental and analytical work.\nMy detailed comments are as follows:\nThe title is overly long and should be shortened for clarity and impact.\nThe abstract frames the problem unclearly and needs reorganization for logical flow.\nIn Fig. 1a, the schematic is confusing: the “reduction center” shows oxidation, and vice versa. The meaning of the arrows\nlinking electrons and holes is ambiguous—do they indicate recombination?\nThe abstract mentions arsenic-containing wastewater purification, but this is not discussed elsewhere. The connection\nbetween catalytic performance and As adsorption/oxidation must be clarified.\nIn Fig. 2a, CTF-TF shows delocalized HOMO–LUMO orbitals. What specific role does fluorine substitution play in\ndifferentiating active sites?\nThe WOR is presented as endergonic; even for the N₂ site, the reaction remains non-spontaneous. How does it proceed\nbeyond OH*? If via OH* dimerization, this step should be shown in the reaction coordinate diagram.\nThe claim that N₁ and N₂ are “confirmed” as oxidation and reduction centers is overstated. The evidence only suggests this\nassignment.\nOptical data (Fig. S19) should be complemented with wavelength-dependent photocatalytic tests to determine the active\nexcitation region.\nThe uniform distribution of active sites is asserted but not demonstrated. Structural or compositional evidence must be\nprovided, as monomer substitution changes redox behavior.\nThe catalyst morphology (micrometer scale) raises concerns about diffusion and porosity effects. Please discuss how mass\ntransport limits the rate and clarify what BET measurements truly probe.\nThe IR spectra (Fig. S14) and XPS fittings (Fig. S15) lack sufficient rigor. Clarify your peak identification and fitting criteria.\nThe XPS fits, in particular, appear unreliable and must be redone.\nH₂O₂ production data are not normalized by the number of active sites or surface area. Explain how variations in BET values\nare accounted for.\nThe non-linear dependence of reactivity on O₂ concentration (Fig. S56) needs explanation.\nRadical quantification (Fig. 4f–g) shows large uncertainty, especially for OH•, and the proposed 2e⁻ ORR + 1e⁻ WOR\nmechanism appears charge-imbalanced. Please revisit this analysis.\nThe paragraph on As(III)/As(V) processes (lines 367–369) mixes redox and adsorption effects in a confusing way. These\nphenomena should be separated and discussed clearly.\nThe role of pH on in-situ H₂O₂ formation and As(III) oxidation kinetics should be addressed explicitly.\nIn summary, the manuscript presents an interesting idea but lacks coherence in its mechanistic rationale and supporting\nevidence. The experimental data are not sufficiently robust or consistent to substantiate the claims. Substantial\nreorganization, additional experiments, and clearer mechanistic validation would be required for the work to reach\npublishable quality.", "reviewer_3": "I co-reviewed this manuscript with one of the reviewers who provided the listed reports. This is part of the Nature Communications initiative to facilitate training in peer review and to provide appropriate recognition for Early Career Researchers who co-review manuscripts.", "reviewer_4": "The paper from Li et al. proposes a fluorine substituted molecular organic junction catalyst for efficient hydrogen peroxide\nphotosynthesis. By tuning the coordination number of the F-substituted benzene linker, spatially separated oxidation-\nreduction centers were obtained to boost oxygen reduction and water oxidation reactions for hydrogen peroxide production.\nOverall, the paper is well written and proposes significant advancement to this field. Therefore, it is recommended for\npublication in Nature Communications after addressing the following minor issues.\nComments to authors\n1. The authors should provide some explanation for the observed reduction in H2O2 production rates in real water compared\nto pure water.\n2. The authors should add the important characterization data of CTF from Supplementary Information to main manuscript,\nsince the innovation of this paper lies in catalyst design.\n3. The authors should explain why the peak of FTIR will blue shift as pressure increases.\n4. In-situ EPR is an important method to capture the continuous generation process of active species, and thus detailed test\nprocedures and experimental photograph should be provided.\n5. The authors should standardize the writing of all free radicals."}, "author_response": "We highly appreciate the positive comments from the reviewer, and they are all considered in corrected manuscript.\n1. Although the introduction outlines the design concept of spatially separated redox\ncenters and identifies the corresponding molecular structures, direct evidence\nconfirming their respective roles as oxidation and reduction sites is lacking. Additional\nexperimental or characterization data are necessary to substantiate this claim.\nAuthor response: We appreciate the reviewer’s critical comments. I sorry that the\nprevious version did not mention the experimental evidence or characterization data\nregarding the oxidation and reduction sites in CTF-TF-0.5. Here, we have identified and\nreviewed a number of literatures on experimentally distinguishing oxidation and\nreduction sites. Currently, two primary experimental approaches are employed: i, TEM\nanalysis of oxidation or reduction sites. Specifically, noble metals (platinum particles)\nare typically deposited as reduction products, while lead oxide or manganese oxide\nare deposited as oxidation products. After they were successfully deposited, TEM\nanalysis was used to locate the position of these products to identify the respective\nsites where catalytic oxidation and reduction occur (Appl. Catal. B: Environ. 2021, 281,\n119479; Nat. Commun. 2023, 14, 3901); ii, Specific site poisoning experiments. By\nintroducing specific probe molecules to poison surface active sites, quantifying the\nproducts of corresponding oxidation and reduction reactions enables the assessment\nof the active role of oxidation and reduction sites (Angew. Chem. Int. Ed. 2021, 60,\n16607-16614).\nHowever, TEM analysis of oxidation or reduction sites is only applicable to lattice\nmaterials discernible under high-magnification TEM, such as materials with crystal\nfaces exhibiting different redox activities or heterojunction materials containing\ndistinct oxidation and reduction components. Specific site poisoning experiments are\nexclusively applicable to modified materials possessing specific active sites, such as\nactive metal sites or organic functional groups.\nHere, we conducted extensive literature research and considered using\nsupplementary experiments or characterization data to demonstrate their respective\nroles as oxidation and reduction sites (the triazine ring connecting two benzene rings\nand one fluorinated benzene ring acts as a oxidation site, while the triazine ring\nconnecting one benzene ring and two fluorinated benzene rings acts as an reduction\nsite) (Figure 1c). Unlike conventional oxidation and reduction sites, the redox sites in\nour proposed CTF-TF-0.5 are determined by the distinct chemical microenvironments\nsurrounding the triazine ring. Therefore, both the oxidation and reduction sites in CTF-\nTF-0.5 are the triazine ring. Consequently, it is challenging to distinguish between the\nsame structure using conventional methods such as TEM analysis of oxidation or\nreduction sites or specific site poisoning experiments. Existing techniques cannot\neffectively identify the active sites responsible for oxidation and reduction within the\nsame structure with different redox properties. Therefore, in the revised version, we\nfurther confirm the proposed structure and separable redox sites in CTF-TF-0.5\nthrough additional characterization and theoretical computational simulations,\nincluding solid-state NMR spectra, time-dependent density functional theory (TD-\nDFT) for electron-hole distribution and Density of states (DOS), combined with our\nprevious HOMO-LUMO analysis (Figure 2a) and G diagram (Figure 2b).\nFigure 1c, Gradual increase in the number of F substitutions to tune the oxidation-\nreduction sites of CTFs.\nHere, firstly, we demonstrate the chemical environment and structural integrity\nusing solid-state NMR (13C, 1H, and 19F) spectroscopy (Figure 3a and Figure S17). In the\nCP-MAS 13C-NMR spectrum, the CTF-1 demonstrates the obvious carbon signals from\nthe triazine units at 170.4 ppm (a) and the phenyl carbons (b and c) at 138.8 ppm and\n128.7 ppm. In the CTF-TF, the carbon signal of triazine rings shifts to 159 ppm because\nof the introduction of fluorine atoms (a’), and the carbon signal of fluorinated benzene\nrings are located at 145.1 ppm (c’). Moreover, the carbon atoms connected with\ntriazine rings display a peak at 119 ppm (b’). Note that the CTF-TF-0.5 simultaneously\ndisplayed the carbon signals (a and a’) from the triazine units without and with fluorine\natoms and the phenyl carbons (b and c), and the carbon signal (c’) of fluorinated\nbenzene rings, and the carbon atoms connected with triazine rings (b’), which\nindicated that CTF-TF-0.5 contains both a benzene ring and a fluorine-substituted\nbenzene ring (Nat. Commun. 2023, 14, 8114).\nThe solid-state 1H NMR spectra of CTF-1 and CTF-TF-0.5 exhibit a signal at\napproximately 7.5 ppm, originating from H atom on the benzene ring. The solid-state\n19F NMR spectra of CTF-TF-0.5 and CTF-TF exhibit a signal at approximately -144 ppm,\noriginating from F atom on fluorine-substituted benzene ring. All these\ncharacterizations fully indicate that CTF-1, CTF-TF-0.5 and CTF-TF was successfully\nsynthesized.\nFigure 3a Solid-state 13C NMR spectra and possible structural model representation.\nFigure S17: Solid-state 1H (a) and 19F (b) NMR spectra and possible structural model\nrepresentation (c).\nTime-dependent density functional theory (TD-DFT) calculations indicated that\nelectrons are primarily localized in the triazine-connected region comprising one\nbenzene and two F-substituted benzenes, while holes are predominantly localized in\nthe triazine-connected region comprising two benzenes and one F-substituted\nbenzene in CTF-TF-0.5 (Figure S1). In contrast, the electron and hole distribution\nregions on the surfaces of CTF-1 and CTF-TF exhibit no distinct characteristic patterns.\nFor catalytic reactions, the energy band positions of highest occupied molecular\norbital (HOMO) and lowest unoccupied molecular orbital (LUMO) determine the\noxidation and reduction capacities, and their spatial distribution determines the\ndistribution of oxidation-reduction site on the catalyst molecular. As shown in our\nmanuscript, CTF-TF-0.5 exhibited a clear separated spatial distribution of HOMO and\nLUMO. Specially, its HOMO is localized at the triazine connected two benzene and a F-\nsubstituted benzene (N1), while LUMO is localized at the triazine connected a benzene\nand two F-substituted benzene (N2). In contrast, both CTF-1 and CTF-TF showed\nirregular and overlapping spatial distributions of LUMO and HOMO (Figure 2a).\nFigure S1: Distribution of holes (blue) and electrons (green) in CTF-1, CTF-TF-0.5 and\nCTF-TF obtained through the time-dependent density functional theory (TD-DFT)\ncalculations (Isosurface value = 0.001). The white, red, cyan, brown and gray colors\nrepresent hydrogen, oxygen, fluorine, carbon and nitrogen.\nThe DFT calculations using the HSE06 hybrid functional were also carried out for\nCTF-1, CTF-TF-0.5 and CTF-TF, and the band structures and projected density of states\n(PDOS) are shown in Figure S2. In CTF-TF-0.5, the VB and CB edges (HOMO and LUMO)\nhave large DOS peaks, which are related to their molecular origin. The PDOS of the VB\nand CB edge simultaneously present more nitrogen orbital contributions. This suggests\nthat the VB and CB originate from N on the triazine ring and trace amounts of C in\nCTF-TF-0.5. However, the elemental orbital distributions of the VB and CB edges\n(HOMO and LUMO) in CTF-1 and CTF-TF do not exhibit characteristic distributions.\nIt can be observed that the microenvironments of the triazine ring in CTF-TF-0.5\ndiffer between N1 and N2. Furthermore, to accurately distinguish the contributions of\nN1 and N2 on the triazine ring to the VB and CB edges, we selected a single CTF-TF-0.5\nsingle unit for DOS analysis. As shown in Figure S3, the PDOS of HOMO has higher N1\n2p orbital contributions, while the LUMO has more N2 2p orbital contributions. This\nsuggests that the VB comes from the triazine connected two benzene and a F-\nsubstituted benzene (N1), while the CB edge comes from the triazine connected a\nbenzene and two F-substituted benzene (N2), which agrees with the molecular orbitals,\nas shown in Figure 2a, where the results of theoretical simulations of HOMO/LUMO\nand distribution of holes and electrons originate from the donor N2 and acceptor N1,\nrespectively.\nFigure S2 Density of states of CTF-1 (a), CTF-TF-0.5 (b) and CTF-TF (c). The inset show\nthe DOS regions for LUMO and HOMO in CTF-TF-0.5.\nFigure S3 Selected DOS analysis region for a single CTF-TF-0.5 unit (a). DOS of different\nN 2p with HOMO (b) and LUMO (c) region in single CTF-TF-0.5 unit.\nTo further verify the feasibility of H O photosynthesis in CTFs with different\n2 2\noxidation and reduction sites, we investigated the thermodynamics of the WOR and\nORR on CTF-1, CTF-TF-0.5 and CTF-TF by analyzing Gibbs free energy (ΔG) and\nintermediate configurations (Figures 2b and S4-S11). These results revealed that CTF-\nTF-0.5_N2 exhibited the lowest free energy for ORR to H O , accompanied by a\n2 2\nsequential transition of reactive oxygen intermediates (*O ⁻ to *OOH), followed by\n2\nproton coupling to form H O . Meanwhile, CTF-TF-0.5_N1 showed the lowest free\n2 2\nenergy for WOR to H O , with a reactive oxygen intermediate (*OH), which then\n2 2\ncombines to produce H O . These confirmed that the N1 site of CTF-TF-0.5 serves as\n2 2\nthe oxidation site for WOR, while the N2 site acts as the reduction site for ORR.\nMoreover, CTF-TF-0.5 facilitates more efficient bulk charge separation of\nphotogenerated carriers into distinct molecular units, enhancing H O overall\n2 2\nphotosynthesis compared to CTF-1 and CTF-TF.\nBased on the all above results, we proposed a spatially separable oxidation-\nreduction assignments in CTF-TF-0.5 that the N1 site of CTF-TF-0.5 serves as the\noxidation site for WOR, while the N2 site acts as the reduction site for ORR.\nOur modification to the manuscript: The corresponding description was added to the\nrevised manuscript (Pages 5 and 7, Figure 3a) and Supplementary Information\n(Figures S1-S3). The specific calculation process has also been added in Text S8.\n2. The reported H O production activity was measured under simulated sunlight using\n2 2\na full-spectrum xenon lamp at 150 mW cm-2 without an AM 1.5G filter. To accurately\nreflect solar conditions, performance should be evaluated under standard AM 1.5G\nirradiation, and the solar-to-chemical conversion (SCC) efficiency should be calculated\nto enable comparison with other catalytic systems.\nAuthor response: We appreciate the reviewer’s professional comments. Based your\nsuggestion, we have added the data on the photocatalytic H₂O₂ production\nperformance using the AM-1.5G filter with and without Us, and the solar-to-chemical\nconversion (SCC) efficiency with mechanical force was also calculated.\nFigure S55 Time profiles of CTFs for H O photosynthesis using the AM-1.5G filter with\n2 2\nand without Us. Experimental conditions: catalyst (0.125 g L−1) under Us and light, T =\n25°C, water.\n5 mg CTF-TF-0.5 was fully dispersed into the 100 mL beaker containing 40 mL\naqueous solution in dark before photocatalytic reaction ultrasound. Then, the\nphotocatalyst was stirred for 1 h in ambient condition under the irradiation by a xenon\nlamp (AM 1.5). The SCC efficiency (η) was calculated by [PNAS, 2021, 118,\ne2115666118]:\n𝜂(%) =\n𝐺𝐻2𝑂2  𝑛𝐻2𝑂2\ntir  Sir  IAM\nwhere 𝐺 is the free energy for H O production (117 × 103 J mol-1), 𝑛\n𝐻2𝑂2 2 2 𝐻2𝑂2\nis the amount of generated H O (mol) and t is the irradiation time (s). The overall\n2 2 ir\nirradiation intensity (I ) of the AM 1.5 global spectrum (300-2500 nm) is 0.1 W cm-2\nAM\nand the irradiation area (S ) is 3.14 × cm-2.\nir\nThe SCC of CTFs with and without mechanical force assistance was calculated in Text\nS7 and Table S4. CTF-TF-0.5 with mechanical force exhibited the highest SCC of 0.16%\nrelative to other scenarios, surpassing the typical photosynthetic efficiency of plants\nof 0.10% (Nat. Commun. 2025, 16, 7654), and this SCC demonstrated the excellent\nperformance compared to the reported catalysts (Table S5).\nTable S4. The comparison of the SCC efficiencies of CTF-1, CTF-TF-0.5 and CTF-TF.\nCatalytic system n (mol) SCC (η, %)\nH2O2\nCTF-TF-0.5/Us/Light 0.016 0.16\nCTF-TF/Us/Light 0.0057 0.059\nCTF-1/Us/Light 0.0075 0.077\nCTF-TF-0.5/Light 0.0073 0.075\nCTF-TF/Light 0.0030 0.031\nCTF-1/Light 0.0025 0.026\nTable S5. The comparison of the SCC efficiencies of CTF-TF-0.5 and other reported\npolymer photocatalysts.\nCatalysts SCC (%) Ref.\ng-C N /PDI 0.10 20\n3 4\ng-C N /BDI 0.13 21\n3 4\ng-C N /PDI/rGO 0.20 22\n3 4\n0.57\nCOF-TfpBpy 23\n1.08\nPM-CDs-30 0.21 24\nNv-C≡N-CN 0.23 25\nAPFac resins 0.54 78\nTPT-alkynyl-AQ 0.35 26\nrGO@MRF-0.5 1.23 79\nSA-TCPP 1.2 80\nCNIO-GaSA 0.4 27\nRF-base resins 0.5 28\nRF-acid-resins 0.7 81\nRF/P HT 1 29\nDE7-M 0.23 30\no-COF-TpPzda 0.46 46\nPyIm-COF 0.28 34\nTpPa/TpDz 1.34 35\nTpPm 1.84 36\nB[f]QCOF-1 0.23 37\nCOF-JLU90 1.52 38\nTBC-COF 0.77 49\nTTT-COF 0.32 41\nTAPT–FTPB COFs 1.22 52\nBTT-H3 COF 2.02 43\nBTTA-COF 0.48 54\ng-C N 0.14 76\n3 4\nPHI 0.18 76\nC N 2.6 76\n5 2\nCTF-TF-0.5 0.16 This work\nOur modification to the manuscript: The corresponding description was added to the\nrevised manuscript (Page 14) and Supplementary Information (Text S7, Figure S55 and\nTables S4-S5).\n3. Given the light absorption of catalysts up to 600 nm, measuring the apparent\nquantum yield (AQY) at specific wavelengths across the 360-600 nm range is\nrecommended. Comparative AQY values against established high-performance\ncatalysts would strengthen the performance assessment.\nAuthor response: We appreciate the reviewer’s professional comments.\n8/46\nApparent quantum yield measurements: For apparent quantum yield (AQY)\nmeasurements, 5 mg catalyst was dispersed in 40 mL. A 300 W Xe-lamp with a band-\npass filter of 380±15 nm, 420±15 nm, 450±15 nm, 500±15 nm, 550±15 nm and 600±15\nnm was used as the incident light source. The light intensity was adjusted to be 4.51\nmW cm-2, 3.21 mW cm-2, 3.56 mW cm-2, 5.93 mW cm-2, 7.45 mW cm-2 and 6.49 mW\ncm-2 cm-2, respectively. The irradiation area was controlled to be 3.14 cm2. The amount\nof H O production was analyzed after 1 h irradiation. AQY was calculated using the\n2 2\nfollowing equation:\nAQY% = 2 × (N ·N ·h·c) / (I·S·t·λ) ×100%\nH2O2 A\nwhere N was the amount of H O production (mol), N was the Avogadro\nH2O2 2 2 A\nconstant (6.022×1023 mol-1), h was the Planck constant (6.626×10-34 J·s), c was the\nspeed of light (3×108 m·s-1), I was the irradiation intensity (W·cm-2), S was the\nirradiation area (cm2), t was the irradiation time (s) and λ was the wavelength of\nincident light (m).\nThe AQY of CTF-TF-0.5 was calculated at specific wavelengths and shown to\napproximately match with the UV-Vis spectrum (Figure S51). CTF-TF-0.5 exhibited an\nAQY of H O production close to 23.9%, 24.1%, 17.6%, 6.9%, 4.3% and 3.4% at\n2 2\nwavelengths of 380 nm, 420 nm, 450 nm, 500 nm, 550 nm and 600 nm, respectively,\nwhich demonstrated the excellent AQY at 420 nm compared to the reported catalysts\n(Table S2). Overall, CTF-TF-0.5 exhibited the high photocatalytic activity of H O\n2 2\nproduction.\nFigure S51: Apparent quantum yield (AQY) of H O production at specific wavelengths\n2 2\nsuperimposed with its UV-Vis absorption curve.\nTable S2. The comparison of AQY of CTF-TF-0.5 at 420 nm and other reported polymer\nphotocatalysts.\nCatalysts AQY (%) Ref.\n9/46\ng-C N /PDI 2.6 20\n3 4\ng-C N /BDI 4.6 21\n3 4\n6.1 22\ng-C N /PDI/rGO\n3 4\nCOF-TfpBpy 8.1 23\nPM-CDs-30 0.98 24\nNv-C≡N-CN 1.8 25\nTPT-alkynyl-AQ 18 (425 nm) 26\nCNIO-GaSA 7.1 (459 nm) 27\nRF-base resins 7.8 28\nRF/P HT 10.6 29\nPor-HQ-COF 5.05 31\nPy-OH-Sa COF 5.78 32\n.ACOF-S-EtOH 13.3 33\nPyIm-COF 3.7 34\nTpPa/TpDz 55 35\nTpPm 22.7 36\nB[f]QCOF-1 8.9 (450 nm) 37\nCOF-JLU90 7.1 38\nAlCCOF-1 7.1 39\nCOF-OMe 6.5 (400 nm) 40\nTTT-COF 12 (400 nm) 41\nDT TA-TAPB 2.8 42\nBTT-H3 COF 17.7 (467 nm) 43\nCOF-N32 6.2 (459 nm) 44\nTTF@Por-COF-cya 14.98 45\nCTF-TF-0.5 24.12 This work\nOur modification to the manuscript: The corresponding description was added to the\nrevised manuscript (Page 13) and Supplementary Information (Text S6, Table S2 and\nFigure S51).\n10/46\n4. While the catalyst demonstrates high H O production activity, direct comparative\n2 2\ndata with existing systems are not provided. Inclusion of such comparisons would\nbetter contextualize its performance and highlight any competitive advantages.\nAuthor response: We appreciate the reviewer’s professional comments. Here, we\nprovided a direct comparative data with existing systems. Since there are few reports\non the production of H O by applying both external force and light, I summarized the\n2 2\nH O production performance reported covalent organic frameworks photocatalysts,\n2 2\nall piezoelectric catalysts and all piezoelectric photocatalysts. Therefore, we have\nfurther summarized the detailed reaction conditions including light intensity,\nultrasound power and frequency, and rotational speed in all reference lists (Table S3)\nfor further comparison. Overall, H O yield we reported exceeds that of most catalysts.\n2 2\nTable S3. H O production rates for CTF-TF-0.5 in this work compared with\n2 2\nrepresentative recently reported work.\nH O\n2 2\nLight Ultrasound Sacrificial\nCatal. Condition (µmol g-1 Ref.\nintensity conditions agent\nh-1)\nPor-HQ-COF Vis - - - 1525 31\nPy-OH-Sa\nLight - - 10% IPA 4780 32\nCOF\no-COF-\nVis - - O 4396 46\nCOF-M180 sunlight 98 mW cm−2 - O 12500 47\nAM 1.5G - - - 5440 33\nEtOH\nPyIm-COF Vis - - 5850 34\nmW·cm−2\nTpPa/TpDz Vis - - O 24420 35\nB[f]QCOFs Vis - - - 9025 37\n100 mW\nCOF-JLU90 AM 1.5 G - - 6432 38\ncm−2\n200 mW O\nAlCCOF-1 Light 2 16794.69 39\ncm−2 10% BA\n300 mW\nCOF-OH Vis - - 4458 40\ncm−2\nTBD-COF White LED 17 mW cm−2 - - 5448 49\nCOF/In S Light - - - 5713.2 50\n2 3\n100 mW\nTTT-COF AM 1.5 10% BA 29900 41\ncm−2\n11/46\nHz-TP-BT-\nVis - - - 5700 51\nCOF\nTAPT–FTPB\nAM 1.5 G - - - 3780 52\nCOFs\nDT TA-TAPB Vis 100 mW cm−2 - - 8587 42\nBTT-H2 Vis - - - 1588 43\n100 mW\nCOF-N32 Vis - - 605 44\ncm−2\n200 mW\nBTTA-COF Vis - - 2650 54\ncm−2\nPor-COF- cya Vis - - - 2290 45\nCNF/SCNF-\nUs/Stirring - 45KW - 62.8 55\nMS\nBTO NSs Us - 125.59 56\n35 kHz MeOH\nAu/BiVO Us - 4-CP 344.4 57\n4\n40 kHz\nTris-\nBiOCl Us - - buffered 420 58\nsolution\nSiO /PVDF- 300 W, 20 vol%\nHFP 40 kHz EtOH\nBiOCl Us/Stirring - - 560 60\n53 kHz\nC N -O Us - - - 615 61\n3 5-X\nC N Us/Stirring - - 680 62\n3 4\nkHz/ 300rpm\nUBTO-OV2 Us - 1611.2 63\n40 kHz EtOH\nBi O Cl Us - - 7760 64\n12 17 2\nkHz\n40 kHz, 240\nBON-M Us - 970.27 65\nW\nMOC-\nUs - 300 W - 120.21 66\nAuNP/gC N\n3 ₄\n40 kH, 200\nBF1.5 Us - - 1305 67\nW\nBC-10 Us - - 1299 68\nkHz\nBIO Us - - 9200 69\nkHz\n12/46\nLFZ Us/Vis - - 403 70\n40 kHz\nBi NbO Br Us/Vis - 792 71\n4 8\nkHz EtOH\nBulk-g-C N Us/Vis - 1080 72\n3 4\nkHz glucose\n100 mW cm– 150 W, 40 10 vol%\nBaTiO :Nb/C Us/Vis 1360 73\n3 2 kHz EtOH\nCOF-DH-Eth Us/Vis - 10W, 49KHz - 9212 74\n100 mW cm– 100 W, 40 10 vol%\nPCCN-10 Us/Vis 4610 75\n2 kHz EtOH\n100 mW cm– 400 W, 40\nC N Us/Vis - 1343.6 76\n5 2 2 kHz\nUiO-66-AQ Us/Light - - 7872.4 77\nkHz\nUs/\n150 mW cm– 100 W, 40 This\nCTF-TF-0.5 Simulating O 4664\n2 kHz 2 work\nsunlight\n100 mW cm– 100 W, 40 This\nCTF-TF-0.5 Us/AM-1.5G - 3114.4\n2 kHz work\n5. Although multiple characterization techniques were employed to verify the catalyst\nstructure, solid-state NMR (13C, 1H, and 19F) spectroscopy could provide further insight\ninto the chemical environment and structural integrity.\nAuthor response: We appreciate the reviewer’s professional comments. In the revised\nversion, we further demonstrate the chemical environment and structural integrity\nusing solid-state NMR (13C, 1H, and 19F) spectroscopy. The specific description has been\ndisplayed in our response to your Comment 1. See your Comment 1\nOur modification to the manuscript: The corresponding description was added to the\nrevised manuscript (Page 7, Figure 3a) and Supplementary Information (Figure S17).\n6. The authors suggest that the catalyst can adsorb O from air (Figure 4a). O -\n2 2\ntemperature-programmed desorption (O -TPD) experiments are recommended to\n2\nquantitatively assess O adsorption capacity and offer more direct evidence.\nto produce H O , O adsorption on the surface of the catalyst is the first step. The O\n2 2 2 2\ntemperature-programmed desorption (O -TPD) curve reveals that CTF-TF-0.5 has a\n2\nhigher O adsorption (0.65 m mol g-1) than CTF-1 (0.20 m mol g-1) and CTF-TF (0.14 m\n2\nmol g-1) (Figure S61).\n13/46\nFigure S61: O -TPD curves of CTF-TF-0.5, CTF-1 and CTF-TF.\nSupplementary Information (Figure S61).\n7. Figure 4c indicates a high H O production rate over 6 hours, with an approximately\n2 2\nlinear increase and no sign of plateau. Extending the reaction duration would help\ndetermine the maximum H O yield, while post-reaction characterization of the\n2 2\ncatalyst would aid in evaluating its stability.\nAuthor response: We appreciate the reviewer’s professional comments. CTF-TF-0.5\ndemonstrated excellent stability during the first six cycles. However, as the reaction\nprogressed, the accumulation of H₂O₂ within the system gradually increased and\nstabilized at approximately 23.65 mmol g⁻¹·h⁻¹. The H₂O₂ generation rate decreased\nfrom 3.13 mmol g⁻¹·h⁻¹ during the initial hour to 0.72 mmol g⁻¹·h⁻¹ over the subsequent\n10 h (Figures 5d). The FT-IR spectra showed little change before and after the reaction,\nfurther confirming its excellent stability for catalytic reactions (Figures S57).\nFigure 5d: Stability of CTF-TF-0.5 over 10 h.\n14/46\nFigure S57: FT-IR spectrum of fresh and used CTF-TF-0.5.\nOur modification to the manuscript: The corresponding description was added to the\nrevised Manuscript (Figure 5d) and Supplementary Information (Figures S57).\n8. Although isotope labeling experiments confirm the H O oxidation pathway for H O\n2 2 2\nformation, rotating ring-disk electrode (RRDE) measurements are advised to\ndetermine the electron transfer number and H O selectivity for the O reduction\n2 2 2\npathway, thereby offering more comprehensive mechanistic insight.\nAuthor response: We appreciate the reviewer’s professional comments. The electron\ntransfer pathway was evaluated by rotating ring-disk electrode (RRDE) analysis at 1600\nrpm in O saturated phosphate buffer solution (0.1 M, pH 7) (P. Natl. Acad. Sci. 2021,\n2\n118, e2103964118).. The ORR polarization curves are displayed in Figure S63.\nCompare with CTF-1 and CTF-TF, CTF-TF-0.5 shows the higher onset potential (0.38 V\nvs. 0.29 V and 0.23 V), and significant higher ring current (Figure S63a). A high H O\n2 2\nyield with 89% selectivity at 0.00 V (vs. RHE) is observed in CTF-TF-0.5 (Figure S63b).\nBesides, in contrast to CTF-1 and CTF-TF, CTF-TF-0.5 shows approximately two-electron\n(2e-) transfer (Figure S63c) from -0.2 V to 0.0 (vs. RHE). These results indicate triazole-\nbased CTF-TF-0.5 has outstanding 2e− ORR for H O production with high selectivity.\n2 2\n15/46\nFigure S63: The electrochemical production of H O . a, ORR polarization curves. b,\n2 2\nH O selectivity. c, the corresponding number of transferred electrons.\n2 2\nOur modification to the manuscript: The corresponding description was added to the\nrevised Manuscript (Page 15) and Supplementary Information (Figures S63).\n9. The authors propose that H O generation proceeds via indirect pathways involving\n2 2\nradicals such as *OH or *O -. Scavenging experiments are recommended to further\n2\nvalidate the contributions of these active species.\nAuthor response: We appreciate the reviewer’s professional comments. Based on\nyour suggestion, 1, 2 and 5 mM of scavengers were added to the initial solution in\nphotocatalytic H O production with Us. TBA for *OH have little effect on the\n2 2\nproduction of H O . It is clearly visible, p-BQ for *O − mainly contribute to H O\n2 2 2 2 2\nproduction, and with the increase of p-BQ, the production of H O gradually decreases.\n2 2\nFigure S64: Scavenger tests of CTF-TF-0.5 in photocatalytic H O production with Us at\n2 2\n60 min (TBA for *OH, p-BQ for *O –, C=1, 2, 5 mM).\n2\n16/46\nOur modification to the manuscript: The corresponding description was added to the\nrevised Manuscript (Page 15) and Supplementary Information (Figure S64).\n10. While the effect of pH on As3+ oxidation was examined, the influence of pH on the\nphotocatalytic generation of H O should also be investigated to fully assess the\n2 2\napplicability of catalysts across varying reaction conditions.\nAuthor response: We appreciate the reviewer’s professional comments. H O at\n2 2\nmillimolar level was produced over CTF-TF-0.5 over a wide pH range (pH 1–13), with\nhigher yields obtained at lower pH (down to pH 3.0) due to elevated proton\nconcentrations in acidic media (Figures S56). However, the H O production activity\n2 2\nsignificantly decreased when the pH was further lowered from pH=3 to pH=1, which\nmay be due to that the occurrence of the competitive reaction of H evolution\n2\n(2𝐻++2𝑒− → 𝐻 2 (0 V 𝑣𝑠.NHE)) along with the production of H 2 O 2 (Nat. Commun. 2023,\n14, 5742).\nFigure S56: Time profiles of photocatalytic H O production by CTF-TF-0.5 under Us\n2 2\nover a wide pH range (pH=1, 3, 7, 10 and 13).\nOur modification to the manuscript: The corresponding description was added to the\nrevised Manuscript (Page 14) and Supplementary Information (Figure S56).\nThank you very much again for your kind and appropriate comments. We are sure\nthat these comments help improve the quality of our manuscript significantly.\nSincerely yours,\nJunhao Qin\n17/46\nReviewer #2 (Remarks to the Author):\nSummary Comments: I have read the manuscript titled “Substituent coordination\ninducing oxidation-reduction molecular organic junction to boost heterogeneous\ninterfacial hydrogen peroxide generation” by Li et al. with interest. The work addresses\nthe construction of molecular organic frameworks with spatially separated redox\ncenters to enhance photocatalytic H₂O₂ generation and arsenic removal. While the\ntopic is relevant and potentially impactful, the manuscript suffers from conceptual,\nstructural, and analytical weaknesses that currently preclude publication in its present\nform. I recommend rejection at this stage, with the possibility of resubmission after\nmajor revision and significant additional experimental and analytical work. My\ndetailed comments are as follows:\nAuthor response: We appreciate the reviewer’s critical comments, which helped us to\nimprove the overall quality of the manuscript significantly. By following the reviewer’s\ncomments, we have revised the manuscript in a point-by-point manner. In particular,\nwe tried to add more details and clarify ambiguous claims. Our responses and\nmodifications are as follows:\n1. The title is overly long and should be shortened for clarity and impact.\nAuthor response: We appreciate the reviewer’s critical comments. The corresponding\ntitle has been revised using “Substituent-induced oxidation-reduction molecular\norganic junction for interfacial hydrogen peroxide photosynthesis”.\n2. The abstract frames the problem unclearly and needs reorganization for logical flow.\nAuthor response: We appreciate the reviewer’s professional comments. Based on\nyour suggestion, the corresponding abstract has been revised as follows:\n“The distribution of catalytic active sites critically dictates photocatalytic efficiency,\nbut existing catalyst design operate at the same or adjacent sites still remain\nlimitations toward photocatalytic reaction. To address this, a kind of spatially\nseparable oxidation-reduction assignment in fluorine substituted molecular organic\njunction catalyst (covalent triazine framework, CTF-TF-0.5) is constructed. …..”\nOur modification to the manuscript: The corresponding description was added to\nrevised manuscript (Page 1).\n3. In Fig. 1a, the schematic is confusing: the “reduction center” shows oxidation, and\nvice versa. The meaning of the arrows linking electrons and holes is ambiguous-do\nthey indicate recombination?\nAuthor response: We appreciate the reviewer’s professional comments. According to\nyour suggestions, the corresponding Figures and expressions have been modified in\nthe revised manuscript (Figure 1a).\n18/46\nFigure 1 | Concept of F substituent coordination inducing oxidation-reduction\nmolecular organic junction to promote carrier separation. a, Separated oxidation-\nreduction centers promoting catalytic reaction with carrier separation at the dual\nactive site. D and A: Donor and acceptor molecule. D+ and A−: Donor cation and\nacceptor anion. b, The proposed structures of oxidation-reduction sites. c, Gradual\nincrease in the number of F substitutions to tune the oxidation-reduction sites of CTFs.\nOur modification to the manuscript: The corresponding description was added to\nrevised manuscript (Page 4, Figure 1a).\n4. The abstract mentions arsenic-containing wastewater purification, but this is not\ndiscussed elsewhere. The connection between catalytic performance and As\nadsorption/oxidation must be clarified.\nAuthor response: We appreciate the reviewer’s professional comments. As you\nmentioned, I am very sorry that the previous version did not address the connection\nbetween catalytic performance and As adsorption/oxidation. Here, we further\ninvestigated the variation in in-situ H₂O₂ generation during all As oxidation processes.\nBy incorporating experiments with different concentrations of As and quenching\nexperiments during oxidation, we ultimately analyzed the relationship between As\nconcentration for oxidation and in-situ H₂O₂ generation. Additionally, we probed the\nreaction mechanism of CTF-TF-0.5 for piezo-photocatalytic oxidation of As (III).\nAs shown in Figures S75a and S75b, CTF-TF-0.5 showed the highest oxidation rate\nof As (III) (77.6%) at 500 g L-1 with the rapid oxidation rate constant relative to that at\n1000 g L-1 (58.8%) (Figure S75c), while the concentration of As (V) gradually increased.\nDuring the degradation, the production of H₂O₂ also shows a positive correlation with\nits oxidation capacity of As (III) (Figure S75d). The corresponding adsorption capacity\nwas also shown in Figure S76.\nFurthermore, we investigated the reaction mechanism of piezo-photocatalytic H₂O₂\n19/46\nproduction for As (III) oxidation. Scavengers were added to the initial solution in\nphotocatalytic As (III) oxidation with Us. TBA for *OH have no effect on As (III) oxidation,\nwhile p-BQ for *O − have some effect for that. Note that catalase for H₂O₂ mainly\n2\ncontribute to As (III) oxidation, due to that the addition of catalase resulted in its near-\ntotal loss of oxidation capacity (Figure S77). These results clearly demonstrate that As\n(III) oxidation via piezo-photocatalysis was directly utilized for the oxidation of As (III),\nwithout conversion into other reactive species.\nFigure S75: a and b, Time profiles (a) and degradation rate (b) of CTF-TF-0.5 in 1 h for\nAs (III) oxidation with different concentration. c, The first-order kinetics model of CTF-\nTF-0.5. d, in-situ generated H O ..\n2 2\nFigure S76: The oxidation amount of As (III) and the production and adsorption\namounts of As (V) of CTF-TF-0.5 at 1 h with different concentration.\n20/46\nFigure S77: a, Time profiles (a) of CTF-TF-0.5 in 1 h for As (III) oxidation with different\nsacrificing agents. b, The corresponding histograms of As (III) and As (V) at 60 min. (2\nmM TBA for *OH, 2 mM p-BQ for *O –, 500 U/mL catalase for H₂O₂).\nincreases, the catalytic performance of the in-situ generated H₂O₂ in the piezo-\nphotocatalytic oxidation of As (III) gradually decreases. Furthermore, the catalytically\ngenerated H₂O₂ was directly utilized for As (III) oxidation without being converted into\nany intermediate active species.\nOur modification to the manuscript: The corresponding description was added to\nrevised manuscript (Pages 18-19) and Supplementary Information (Figures S75-S77).\n5. In Fig. 2a, CTF-TF shows delocalized HOMO-LUMO orbitals. What specific role does\nfluorine substitution play in differentiating active sites?\nAuthor response: We appreciate the reviewer’s critical comments. The triazine ring\n(C₃N₃) is a nitrogen-rich aromatic heterocycle, endowing it with fundamental\nadvantages as a material building block. It inherently functions as an electron-deficient\naromatic ring. The highly electronegative nitrogen atoms on the ring induce electron\nwithdrawal from the ring via inductive and conjugation effects, making it a natural\nelectron reservoir (Chem. Rev. 2021, 121, 23, 14555-14593).\nAs shown in Figure 1c, unlike the bare CTF-1 without fluorine substitution, we\nobtained CTF-TF-0.5 and CTF-TF with varying degrees of fluorine substitution by\ncontrolling monomer substitution. As depicted in electrostatic potential in Figure\nanswering 1, the F site exhibits a strongly electron-rich localized region compared to\nboth the triazine and benzene rings. Consequently, the highly electronegative F atom\ninduces electron density toward itself. At the molecular level, when fluorine\nsubstitutes the benzene ring, the attracted electrons are primarily “locked” around the\nC-F bond (Nat. Commun. 2025, 16, 11024; Appl. Catal. B: Environ. Energy 2026, 384,\n126228). However, the triazine ring, acting as a bridge between the benzene ring and\nthe fluorinated benzene ring, possesses a specific position and unique delocalized\nelectron storage capacity. This allows the electrons locked at the C-F bond to rapidly\nencounter the entire -conjugated system. Therefore, the number of triazine-linked\nfluorinated benzene rings significantly influences the molecule's capacity for electron\nstorage and donation, thereby influencing the distribution of delocalized HOMO and\nLUMO orbitals.\n21/46\nAdditional evidence was also used to support the role of F replacement, including\nsolid-state NMR spectra, time-dependent density functional theory (TD-DFT) and\nDensity of states (DOS), etc. See our response to your Comment 9\nFigure 1c Gradual increase in the number of F substitutions to tune the oxidation-\nreduction center of CTFs.\nFigure answering 1 Electrostatic potential distribution of CTF-1, CTF-TF-0.5 and CTF-\nTF\n6. The WOR is presented as endergonic; even for the N₂ site, the reaction remains non-\nspontaneous. How does it proceed beyond OH*? If via OH* dimerization, this step\nshould be shown in the reaction coordinate diagram.\nAuthor response: We appreciate the reviewer’s professional comments. H₂O₂ is\nindeed formed through the dimerization of *OH. Here, combining our previous\nsacrificial agent experiments, gas shielding experiments, EPR, and in-situ EPR\nexperiments (Figure S62, S64, S66 and S71), we have demonstrated the role of *OH in\nWOR to synthesize H O via piezo-photocatalysis.\n2 2\nAccording to your suggestion, the step of *OH dimerization to form H O was\n2 2\nfurther simulated in the reaction coordinate diagram. Initially, after optimizing the\nadsorption sites of two *OH on all CTFs (Figures answering 2 and 3), the most stable\nadsorption conformations were selected (Red), and G diagram for the dimerization\nof two *OH was calculated and added in the reaction coordinate diagram (Figures 2b\nand S11).\n22/46\nFigure answering 2 The top view and side view of 2 *OH in different adsorption\nconformations on CTF-1 (a) and CTF-TF (b) (Red selected as the optimal adsorption\nconformation).\nFigure answering 3 The top view and side view of 2*OH in different adsorption\nconformations on CTF-TF-0.5_N1 (a) and CTF-TF-0.5_N2 (b) (Red selected as the\noptimal adsorption conformation).\n23/46\nFigure 2b: ΔG diagram of CTFs in the ORR and WOR reaction. The insets show the\ntransition state in the ORR and WOR, and the white, red, cyan, brown and gray colors\nrepresent hydrogen, oxygen, fluorine, carbon and nitrogen.\nFigure S11: Transition states of WOR for CTF-1, CTF-TF-0.5_N1, CTF-TF-0.5_N2 and\nCTF-TF.\nOur modification to the manuscript: The corresponding description was added to\nrevised manuscript (Page 5, Figure 2b) and Supplementary Information (Figure S11).\n7. The claim that N₁ and N₂ are “confirmed” as oxidation and reduction centers is\noverstated. The evidence only suggests this assignment.\nAuthor response: We appreciate the reviewer’s critical comments. Indeed, your\nsuggestions are crucial for deeply understanding of our proposed oxidation and\nreduction centers.\nIn previous versions, we used delocalized HOMO-LUMO orbitals simulations and the\nreaction energy barriers occurring at the respective N sites of O₂ and H₂O to verify the\nassignment of oxidation and reduction centers. Here, we have also attempted to use\nexperimental methods to substantiate our viewpoint by reviewing relevant reference.\nHowever, it is challenging to distinguish the redox sites-both of which are triazine rings-\ndue to the differing chemical environments surrounding them, which affect their\nintrinsic activity. The specific analytical process is presented in our response for the\n24/46\nComment 1 of Reviewer 1 and your Comment 9. Moreover, during this, we also added\nadditional characterization and theoretical calculations to further substantiate the\nevidence supporting this assignment, including solid-state NMR spectra, time-\ndependent density functional theory (TD-DFT) and Density of states (DOS), etc.\nTo present our proposed viewpoint more objectively, we will rephrase this\nstatement throughout the text using “oxidation and reduction assignment/site”.\nOur modification to the manuscript: The corresponding description was modified to\nrevised manuscript.\n8. Optical data (Fig. S19) should be complemented with wavelength-dependent\nphotocatalytic tests to determine the active excitation region.\nAuthor response: We appreciate the reviewer’s professional comments.\nApparent quantum yield measurements: For apparent quantum yield (AQY)\nmeasurements, 5 mg catalyst was dispersed in 40 mL. A 300 W Xe-lamp with a band-\npass filter of 380±15 nm, 420±15 nm, 450±15 nm, 500±15 nm, 550±15 nm and 600±15\nnm was used as the incident light source. The light intensity was adjusted to be 4.51\nmW cm-2, 3.21 mW cm-2, 3.56 mW cm-2, 5.93 mW cm-2, 7.45 mW cm-2 and 6.49 mW\ncm-2 cm-2, respectively. The irradiation area was controlled to be 3.14 cm2. The amount\nof H O production was analyzed after 1 h irradiation. AQY was calculated using the\n2 2\nfollowing equation:\nAQY% = 2 × (N ·N ·h·c) / (I·S·t·λ) ×100%\nH O A\n2 2\nwhere N was the amount of H O production (mol), N was the Avogadro\nH2O2 2 2 A\nconstant (6.022×1023 mol-1), h was the Planck constant (6.626×10-34 J·s), c was the\nspeed of light (3×108 m·s-1), I was the irradiation intensity (W·cm-2), S was the\nirradiation area (cm2), t was the irradiation time (s) and λ was the wavelength of\nincident light (m).\nThe AQY of CTF-TF-0.5 was calculated at specific wavelengths and shown to\napproximately match with the UV-Vis spectrum (Figure S51). CTF-TF-0.5 exhibited an\nAQY of H O production close to 23.9%, 24.1%, 17.6%, 6.9%, 4.3% and 3.4% at\n2 2\nwavelengths of 380 nm, 420 nm, 450 nm, 500 nm, 550 nm and 600 nm, respectively,\nwhich demonstrated the excellent AQY at 420 nm compared to the reported catalysts\n(Table S2). Overall, CTF-TF-0.5 exhibited the high photocatalytic activity of H O\n2 2\nproduction.\n25/46\nFigure S51: AQY of H O production at specific wavelengths superimposed with its UV-\n2 2\nVis absorption curve.\nOur modification to the manuscript: The corresponding description was added to the\nrevised manuscript (Page 13) and Supplementary Information (Text S6 and Figure S51).\n9. The uniform distribution of active sites is asserted but not demonstrated. Structural\nor compositional evidence must be provided, as monomer substitution changes redox\nbehavior.\nAuthor response: We appreciate the reviewer’s critical comments. I sorry that the\nprevious version did not mention the experimental evidence or characterization data\nregarding the oxidation and reduction sites in CTF-TF-0.5. Here, we have identified and\nreviewed a number of literatures on experimentally distinguishing oxidation and\nreduction sites. Currently, two primary experimental approaches are employed: i, TEM\nanalysis of oxidation or reduction sites. Specifically, noble metals (platinum particles)\nare typically deposited as reduction products, while lead oxide or manganese oxide\nare deposited as oxidation products. After they were successfully deposited, TEM\nanalysis was used to locate the position of these products to identify the respective\nsites where catalytic oxidation and reduction occur (Appl. Catal. B: Environ. 2021, 281,\n119479; Nat. Commun. 2023, 14, 3901); ii, Specific site poisoning experiments. By\nintroducing specific probe molecules to poison surface active sites, quantifying the\nproducts of corresponding oxidation and reduction reactions enables the assessment\nof the active role of oxidation and reduction sites (Angew. Chem. Int. Ed. 2021, 60,\n16607-16614).\nHowever, TEM analysis of oxidation or reduction sites is only applicable to lattice\nmaterials discernible under high-magnification TEM, such as materials with crystal\nfaces exhibiting different redox activities or heterojunction materials containing\ndistinct oxidation and reduction components. Specific site poisoning experiments are\nexclusively applicable to modified materials possessing specific active sites, such as\nactive metal sites or organic functional groups.\nHere, we conducted extensive literature research and considered using\n26/46\nsupplementary experiments or characterization data to demonstrate their respective\nroles as oxidation and reduction sites (the triazine ring connecting two benzene rings\nand one fluorinated benzene ring acts as a reduction center, while the triazine ring\nconnecting one benzene ring and two fluorinated benzene rings acts as an oxidation\ncenter) (Figure 1c). Unlike conventional oxidation and reduction sites, the redox\ncenters in our proposed CTF-TF-0.5 are determined by the distinct chemical\nmicroenvironments surrounding the triazine ring. Therefore, both the oxidation and\nreduction sites in CTF-TF-0.5 are the triazine ring. Consequently, it is challenging to\ndistinguish between these sites using conventional methods such as TEM analysis of\noxidation or reduction sites or specific site poisoning experiments. Existing techniques\ncannot effectively identify the active sites responsible for oxidation and reduction\nwithin the same structure with different redox properties. Therefore, in the revised\nversion, we further confirm the proposed structure and separable redox sites in CTF-\nTF-0.5 through additional characterization and theoretical computational\nsimulations, including solid-state NMR spectra, time-dependent density functional\ntheory (TD-DFT) and Density of states (DOS), combined with our previous HOMO-\nLUMO analysis (Figure 2a) and G diagram (Figure 2b).\nFigure 1c, Gradual increase in the number of F substitutions to tune the oxidation-\nreduction sites of CTFs.\nHere, firstly, we demonstrate the chemical environment and structural integrity\nusing solid-state NMR (13C, 1H, and 19F) spectroscopy (Figure 3a and Figure S17). In the\nCP-MAS 13C-NMR spectrum, the CTF-1 demonstrates the obvious carbon signals from\nthe triazine units at 170.4 ppm (a) and the phenyl carbons (b and c) at 138.8 ppm and\n128.7 ppm. In the CTF-TF, the carbon signal of triazine rings shifts to 159 ppm because\nof the introduction of fluorine atoms (a’), and the carbon signal of fluorinated benzene\nrings are located at 145.1 ppm (c’). Moreover, the carbon atoms connected with\ntriazine rings display a peak at 119 ppm (b’). Note that the CTF-TF-0.5 simultaneously\ndisplayed the carbon signals (a and a’) from the triazine units without and with fluorine\natoms and the phenyl carbons (b and c), and the carbon signal (c’) of fluorinated\nbenzene rings, and the carbon atoms connected with triazine rings (b’), which\nindicated that CTF-TF-0.5 contains both a benzene ring and a fluorine-substituted\nbenzene ring (Nat. Commun. 2023, 14, 8114).\n27/46\nFigure 3a Solid-state 13C NMR spectra and possible structural model representation.\nFigure S17: Solid-state 1H (a) and 19F (b) NMR spectra and possible structural model\nrepresentation (c).\nThe solid-state 1H NMR spectra of CTF-1 and CTF-TF-0.5 exhibit a signal at\napproximately 7.5 ppm, originating from H atom on the benzene ring, while the solid-\nstate 19F NMR spectra of CTF-TF-0.5 and CTF-TF exhibit a signal at approximately -144\nppm, originating from F atom on fluorine-substituted benzene ring. All these\ncharacterizations fully indicate that CTF-1, CTF-TF-0.5 and CTF-TF was successfully\nsynthesized.\nTime-dependent density functional theory (TD-DFT) calculations indicated that\nelectrons are primarily localized in the triazine-connected region comprising one\n28/46\nbenzene and two F-substituted benzenes, while holes are predominantly localized in\nthe triazine-connected region comprising two benzenes and one F-substituted\nbenzene in CTF-TF-0.5 (Figure S1). In contrast, the electron and hole distribution\nregions on the surfaces of CTF-1 and CTF-TF exhibit no distinct characteristic patterns.\nFor catalytic reactions, the energy band positions of highest occupied molecular\norbital (HOMO) and lowest unoccupied molecular orbital (LUMO) determine the\noxidation and reduction capacities, and their spatial distribution determines the\ndistribution of oxidation-reduction site on the catalyst molecular. As shown in our\nmanuscript, CTF-TF-0.5 exhibited a clear separated spatial distribution of HOMO and\nLUMO. Specially, its HOMO is localized at the triazine connected two benzene and a F-\nsubstituted benzene (N1), while LUMO is localized at the triazine connected a benzene\nand two F-substituted benzene (N2). In contrast, both CTF-1 and CTF-TF showed\nirregular and overlapping spatial distributions of LUMO and HOMO (Figure 2a).\nFigure S1: Distribution of holes (blue) and electrons (green) in CTF-1, CTF-TF-0.5 and\nCTF-TF obtained through the time-dependent density functional theory (TD-DFT)\ncalculations (Isosurface value = 0.001). The white, red, cyan, brown and gray colors\nrepresent hydrogen, oxygen, fluorine, carbon and nitrogen.\nThe DFT calculations using the HSE06 hybrid functional were also carried out for\nCTF-1, CTF-TF-0.5 and CTF-TF, and the band structures and projected density of states\n(PDOS) are shown in Figure S2. In CTF-TF-0.5, the VB and CB edges (HOMO and LUMO)\nhave large DOS peaks, which are related to their molecular origin. The PDOS of the VB\nand CB edge simultaneously present more nitrogen orbital contributions. This suggests\nthat the VB and CB originate from N on the triazine ring and trace amounts of C in\nCTF-TF-0.5. However, the elemental orbital distributions of the VB and CB edges\n(HOMO and LUMO) in CTF-1 and CTF-TF do not exhibit characteristic distributions.\n29/46\nIt can be observed that the microenvironments of the triazine ring in CTF-TF-0.5\ndiffer between N1 and N2. Furthermore, to accurately distinguish the contributions of\nN1 and N2 on the triazine ring to the VB and CB edges, we selected a single CTF-TF-0.5\nsingle unit for DOS analysis. As shown in Figure S3, the PDOS of HOMO has higher N1\n2p orbital contributions, while the LUMO has more N2 2p orbital contributions. This\nsuggests that the VB comes from the triazine connected two benzene and a F-\nsubstituted benzene (N1), while the CB edge comes from the triazine connected a\nbenzene and two F-substituted benzene (N2), which agrees with the molecular orbitals,\nas shown in Figure 2a, where the results of theoretical simulations of HOMO/LUMO\nand distribution of holes and electrons originate from the donor N2 and acceptor N1,\nrespectively.\nFigure S2: Density of states of CTF-1 (a), CTF-TF-0.5 (b) and CTF-TF (c). The inset show\nthe DOS regions for LUMO and HOMO in CTF-TF-0.5.\nFigure S3: Selected DOS analysis region for a single CTF-TF-0.5 unit (a). DOS of different\nN 2p with HOMO (b) and LUMO (c) region in single CTF-TF-0.5 unit.\n30/46\nTo further verify the feasibility of H O photosynthesis in CTFs with different\n2 2\noxidation and reduction sites, we investigated the thermodynamics of the WOR and\nORR on CTF-1, CTF-TF-0.5 and CTF-TF by analyzing Gibbs free energy (ΔG) and\nintermediate configurations (Figures 2b and S4-S11). The results revealed that CTF-TF-\n0.5_N2 exhibited the lowest free energy for ORR to H O , accompanied by a sequential\n2 2\ntransition of reactive oxygen intermediates (*O ⁻ to *OOH), followed by proton\n2\ncoupling to form H O . Meanwhile, CTF-TF-0.5_N1 showed the lowest free energy for\n2 2\nWOR to H O , with a reactive oxygen intermediate (*OH), which then combines to\n2 2\nproduce H O . These confirmed that the N1 site of CTF-TF-0.5 serves as the oxidation\n2 2\nsite for WOR, while the N2 site acts as the reduction site for ORR. Moreover, CTF-TF-\n0.5 facilitates more efficient bulk charge separation of photogenerated carriers into\ndistinct molecular units, enhancing H O overall photosynthesis compared to CTF-1\n2 2\nand CTF-TF.\nBased on the all above results, we proposed a spatially separable oxidation-\nreduction assignments in CTF-TF-0.5 that the N1 site of CTF-TF-0.5 serves as the\noxidation site for WOR, while the N2 site acts as the reduction site for ORR.\nOur modification to the manuscript: The corresponding description was added to the\nrevised manuscript (Pages 5 and 7, Figure 3a) and Supplementary Information\n(Figures S1-S3). The specific calculation process has also been added in Text S8.\n10. The catalyst morphology (micrometer scale) raises concerns about diffusion and\nporosity effects. Please discuss how mass transport limits the rate and clarify what BET\nmeasurements truly probe.\nAuthor response: We appreciate the reviewer’s critical comments. Based on your\nsuggestions, we have re-synthesized and tested the SEM (Figure S13) and specific\nsurface area of CTF-TF-0.5. Consequently, we normalized the synthesis performance\nof H O using specific surface area, demonstrating that catalytic performance does not\n2 2\nstem from specific surface area or pore effects, but rather from the influence of the\ncatalyst's molecular structure itself. Furthermore, your suggestion regarding the\nimpact of mass transfer rates on catalyst performance is excellent; we will\nsystematically present and analyze this in future work due to time constraints at\npresent.\nDuring the experiment, 5 mg catalyst was added in 40 mL pure water for subsequent\nexperiments. Therefore, the experimental specific surface area of CTF-1, CTF-TF-0.5\nand CTF-TF are 1.505, 2.130 and 1.925 m2, respectively. Compared to CTF-1, the BET-\ncharacterized specific surface area showed a slight increase with the gradual increase\nin the number of F coordination, and the specific surface areas of CTF-1, CTF-TF-0.5,\nand CTF-TF were similar. Furthermore, after normalizing the H₂O₂ production\nperformance based on specific surface area, CTF-TF-0.5 still exhibited the highest H₂O₂\nproduction performance. The results of the BET test are ultimately intended to\ndemonstrate that the specific surface area of different CTFs has little effect on H₂O₂\nproduction performance.\n31/46\nFigure S13: SEM images of CTF-1 (a), CTF-TF-0.5 (b) and CTF-TF (c).\nFigure S47: H₂O₂ production data normalized by surface area of all CTFs.\nOur modification to the manuscript: The corresponding description was added to the\nrevised manuscript (Page 13) and Supplementary Information (Figures S13 and S47).\n11. The IR spectra (Fig. S14) and XPS fittings (Fig. S15) lack sufficient rigor. Clarify your\npeak identification and fitting criteria. The XPS fits, in particular, appear unreliable and\nmust be redone.\nAuthor response: We appreciate the reviewer’s critical comments. Based on your\nsuggestions, we have retested the FT-IR and re-simulated the IR spectrum and\nfunctional group vibrational regions using Gauss. Meanwhile, I also retest and refit the\nXPS.\ni, IR spectra\nThe chemical bonding characteristics of CTF-1, CTF-TF-0.5, and CTF-TF were retested\nusing Fourier transform infrared spectroscopy (FT-IR) (Figure 3b). All samples exhibited\ntwo characteristic vibration signals associated with triazine units, appearing in the\nrange of 1300–1600 cm-1. For CTF-1, sharp peaks at 1356 and 1515 cm-1 corresponded\nto triazine unit vibrations, while the peak at 813 cm-1 is attributed to benzene rings.\nSimilarly, CTF-TF-0.5 and CTF-TF displayed peaks at 1356 and 1522 cm-1, indicative of\ntriazine units, along with two additional peak at 1484 and 983 cm-1, assigned to the\nstretching vibrations of C−F bonds (ACS Appl. Mater. Interf. 2017, 9, 37731-37738),\nconfirming the formation of CTF-TF and CTF-TF-0.5. Meanwhile, as the number of F\n32/46\nsubstituents increases, the peak at 812 nm gradually decreases, indicating that the\nbenzene ring is progressively substituted by F as the amount of F substitution increases\n(From CTF-1 to CTF-TF-0.5, then to CTF-TF).\nThen, we also re-simulated the IR spectrum and functional group vibrational regions\nusing Gauss (Figure S18 and S19). All simulated samples also exhibited two\ncharacteristic vibration signals associated with triazine units, appearing in the range of\n1300–1600 cm-1. For CTF-1, sharp peaks at 1395 and 1578 cm-1 corresponded to\ntriazine unit vibrations. Similarly, CTF-TF-0.5 and CTF-TF displayed peaks at 1395 and\n1578 cm-1, indicative of triazine units, along with two additional peak at 1511 and 1022\ncm-1, assigned to the stretching vibrations of C−F bonds. Overall, the FT-IR spectra\nobtained from experimental data and those derived from computational simulations\nexhibit consistent trends, although some peaks show a slight blue shift relative to the\nFT-IR spectra obtained experimentally.\nFigure 3b FT-IR spectra of all CTFs.\nFigure S18: Simulated FT-IR spectra with using Gauss.\n33/46\nFigure S19: Molecular structure model constructed using Gaussian software. Blue\nrepresents N atoms, gray represents C atoms, white represents H atoms, and cyan\nrepresents F atoms.\nOur modification to the manuscript: The corresponding description was added to the\nrevised manuscript (Page 7, Figure 3b) and the Supplementary Information (Figures\nS18-S19).\nii, XPS fitting\nBased on your suggestion, the corresponding XPS fitting has been redone and\nrefitted. The survey X-ray photoelectron spectroscopy (XPS) spectra are shown in\nFigure S20, which displays that the prepared CTF is composed of C and N, and the\nprepared CTF-TF-0.5 and CTF-TF is composed of C, N and F. The small amount oxygen\nis due to the adsorbed CO or H O on the material surface.\n2 2\nThe C 1s XPS spectrum for CTF-1 (Figure S21) shows a sharp peak at 287.07 eV\n(assigned to the N-C=N group) and a sharp peak at 284.8 eV, assigning to the sp2-hybrid\naromatic carbon in benzene ring. As the amount of F substitution gradually increases,\nthe N-C=N bond in CTF-TF-0.5 and CTF-TF was reduced by approximately 1.1 eV, and\nthe C-F gradually increases while the sp2-hybrid aromatic carbon in benzene ring\nprogressively diminishes.\nThe N 1s XPS spectrum (Figure S22) of CTF-1 shows two peaks centered at 398.8\nand 400.3 eV, corresponding to the N species in the triazine units and the N atoms\nfrom the triphenylamine moiety, respectively (Angew. Chem.Int. Ed. 2020, 59, 6007-\n6014; ChemSusChem 2019, 12, 4493-4499). As the F coordination number increases,\nthe two peaks of N 1s exhibit the trend of increased binding energy, and the C-F peak\nsignificantly increase (Figure S22 and S23).\nFigure S20: Survey XPS spectra of CTF-1 (a), CTF-TF-0.5 (b) and CTF-T (c).\n34/46\nFigure S21: C 1s high-resolution XPS spectra of CTF-1 (a), CTF-TF-0.5 (b) and CTF-TF\n(c).\nFigure S22: N 1s high-resolution XPS spectra of CTF-1 (a), CTF-TF-0.5 (b) and CTF-TF\n(c).\nFigure S23: F 1s high-resolution XPS spectra of CTF-1 (a), CTF-TF-0.5 (b) and CTF-TF\n(c).\nOur modification to the manuscript: The corresponding description was added to the\nSupplementary Information (Figures S20-S23).\n12. H₂O₂ production data are not normalized by the number of active sites or surface\narea. Explain how variations in BET values are accounted for.\n35/46\nAuthor response: We appreciate the reviewer’s critical comments. Based on your\nsuggestions, the corresponding H₂O₂ production data have been normalized by surface\narea. These results demonstrate that CTF-TF-0.5 still exhibits the highest H O\n2 2\nsynthesis performance under synergistic light and ultrasound conditions. During the\nexperiment, 5 mg catalyst was added in 40 mL pure water for subsequent experiments.\nTherefore, the experimental specific surface area of CTF-1, CTF-TF-0.5 and CTF-TF are\n1.505, 2.130 and 1.925 m2, respectively. Compared to CTF-1, the BET-characterized\nspecific surface area showed a slight increase with the gradual increase in the number\nof F coordination, and the specific surface areas of CTF-1, CTF-TF-0.5, and CTF-TF were\nsimilar. Furthermore, after normalizing the H₂O₂ production performance based on\nspecific surface area, CTF-TF-0.5 still exhibited the highest H₂O₂ production\nperformance. The results of the BET test demonstrated that catalytic performance\ndoes not stem from specific surface area or pore effects, but rather from the influence\nof the catalyst's molecular structure itself.\nThe specific description has been displayed in our response to your Comment 10.\nSee your Comment 10\nOur modification to the manuscript: The corresponding description was added to the\nSupplementary Information (Figures S16 and S47).\n13. The non-linear dependence of reactivity on O₂ concentration (Fig. S56) needs\nexplanation.\nAuthor response: We appreciate the reviewer’s critical comments. Nonlinear\ndependence can be interpreted as follows: We demonstrated that the mechanism of\nH O synthesis primarily involves the formation of H O through dual pathways of ORR\n2 2 2 2\nand WOR, which was also confirmed by EPR and quenching experiments (Figures S64-\n70). Therefore, even H O under N , WOR to synthesis H O (H₂O → *OH → H O ) still\n2 2 2 2 2 2 2\ncould occur, resulting in a small amount of H O was also generated under N .\n2 2 2\nFigure S62: Effect of dissolved oxygen on H O synthesis of CTF-TF-0.5 in 1 h.\n2 2\n36/46\n14. Radical quantification (Fig. 4f–g) shows large uncertainty, especially for OH•, and\nthe proposed 2e⁻ ORR + 1e⁻ WOR mechanism appears charge-imbalanced. Please\nrevisit this analysis.\nAuthor response: We appreciate the reviewer’s critical comments.\ni, Radical quantification (Fig. 4f–g) shows large uncertainty, especially for OH•\nThe instability and trace nature of signals are normal phenomena in detecting\ntransient radicals using DMPO spin-trapping EPR techniques. Furthermore, the\ncharacteristic DMPO-*OH quadruplet (Figures 5f–g) observed in the study confirms\n*OH generation, which was also validated through EPR software simulation. Moreover,\nin our work, the water oxidation reaction accounted for a low proportion of H₂O₂\nsynthesis (H O → *OH → H O ), which was proved with sacrificial agent and\n2 2 2\natmosphere experiments (Figure S62 and S64). Therefore, the weak signal from *OH\ngeneration in WOR aligns with theoretical expectations and does not undermine the\nreliability of this detection result.\nFigure S71: Simulated EPR spectrum (*O –, *OOH and *OH) during H O production\n2 2 2\nwith Us/light.\nii, the proposed 2e⁻ ORR + 1e⁻ WOR mechanism appears charge-imbalanced.\nThe proposed 2e⁻ ORR + 1e⁻ WOR mechanism refers to that the O is localized at\n2\nintermediates of *O - and *OOH to form H O . Meanwhile, the positive holes localized\n2 2 2\nat N1 oxidized H₂O to form *OH radicals in surface, which subsequently combined to\nproduce H O through a 1e- WOR. This phenomenon of charge imbalance was\n2 2\nattributed to competitive reactions occurring at the WOR site, such as the formation\nof *OH alongside WOR to produce O . Furthermore, we employed deuterated water\n2\nas the reactant and subjected it to vacuum conditions to detect the reaction products\nto explore the reaction pathway for WOR.\nSpecially, CTF-TF-0.5 (1 mg) was added to H 18O (2 mL) in a 20 mL glass tube which\n2\nwas sealed with a rubber stopper. After ultrasound for 1 h, the gaseous product was\nanalyzed by gas chromatography-mass spectrometry (GC-MS). The liquid phase\nproduct was then extracted and the catalyst was removed with a filter tip. MnO was\n2\nthen added to the liquid product and after 30 min, the gaseous product was analyzed\n37/46\nby GC-MS.\nTo investigate the H O production via WOR pathway, an isotopic-labeling\n2 2\nexperiments were carried out using CTF-TF-0.5 as the photocatalyst and H 18O as the\n2\nwater source. As shown in Figure S67a, after the piezo-photocatalysis, 18O existed in\n2\nthe reaction system as gaseous products, suggesting that H 18O could be oxidized to\n2\n18O via a 4e- oxidation pathway. Furthermore, H O generated by piezo-photocatalysis\n2 2 2\nwas decomposed by MnO produced the 18O (Figure S67b), indicating that H 18O was\n2 2 2\nthe raw material for piezo-photocatalytic H O in the WOR pathway, suggesting that\n2 2\nWOR could be also produce H O via *OH dimerization with 1e- WOR pathway,\n2 2\ncombining gas experiments (Figure S62) and quenching experiments (Figure S64).\nThese indicate that the WOR simultaneously undergoes competing reactions: the\noxidation of 4e- to form O and *OH dimerization with a 1e- WOR to form H O .\n2 2 2\nFigure S67: a, GC-MS data of gaseous phase after piezo-photocatalysis of CTF-TF-0.5\nwith H 18O (a) and gas products (b) after H O decomposition with MnO .\n2 2 2 2\nOur modification to the manuscript: The corresponding references has been added in\nthe revised manuscript (Page 15) and Supplementary Information (Figures S67 and\nS71).\n15. The paragraph on As(III)/As(V) processes (lines 367-369) mixes redox and\nadsorption effects in a confusing way. These phenomena should be separated and\ndiscussed clearly.\nAuthor response: We appreciate the reviewer’s critical comments. The redox and\nadsorption effects for As(III)/As(V) have been separated and discussed.\nAs shown in Figures 6a and S72a, CTF-TF-0.5 showed the highest oxidation rate\nof As (III) (63.5%) with the rapid oxidation rate constant relative to CTF-1 (26.8%) and\nCTF-TF (40.6%), while the concentration of As (V) of all CTFs gradually increased.\nDuring the degradation, the production of H₂O₂ also shows a positive correlation with\nits oxidation rate of As (III) (Figures S72b and S72c). Interestingly, the adsorption of As\n(V) in CTF-TF-0.5 was significantly higher than those of CTF-1 and CTF-TF, which was\nattributed to the excellent adsorption capacity of CTF-0.5 for As (V) (Figure S72d).\nThe effect of different pH on As oxidation was also evaluated in the Figure 6c, the\nconcentration of As (III) was completely oxidized within 90 min at pH=3 and displayed\na highest oxidation rate of 0.0527 min-1 (Figure S74a), while As(V) could be adsorbed\nup to 54.2% at 3h, which were both significantly higher than those at pH=7 and pH=10.\n38/46\nThese indicated that the oxidation of As (III) increased significantly and As (V) was\nadsorbed in large quantities with the decrease of pH. During 3 h reaction, it also\nexhibits a continuously increasing H₂O₂ concentration at pH=3, reaching 471.5 M at\n3 h, which was significantly higher than that at pH=7 and pH=10 (Figures S74b and\nS74c). The adsorption of As (V) in CTF-TF-0.5 at pH=3 was significantly higher than\nthose at pH=7 and pH=10, which was due to the adsorption of As (V) could be\npromoted under acid condition (Figure S74d).\nFigure 6 | Evaluation of environmental applications for mine wastewater treatment.\na and b, Time profiles of all CTFs in 1 h (a) and CTF-TF (b) in 3 h for heterogeneous\ninterfacial As (III) oxidation. c, The effect of different pH. d, As-containing mine\nwastewater treatment. The inset shows the photographs of wastewater during the\ndegradation process.\nFigure S72d: The oxidation amount of As (III) and the production and adsorption\namounts of As (V) of CTF-1, CTF-TF-0.5 and CTF-TF at 1 h.\n39/46\nFigure S74d: The oxidation amount of As (III) and the production and adsorption\namounts of As (V) of CTF-TF-0.5 at pH=3, 7 and 10 over 3 h.\nOur modification to the manuscript: The corresponding description was added in the\nrevised manuscript (Pages 18-19) to Supplementary Information (Figures S72d and\nS74d).\n16. The role of pH on in-situ H₂O₂ formation and As (III) oxidation kinetics should be\naddressed explicitly.\nAuthor response: We appreciate the reviewer’s professional comments.\nBased on your suggestion, we investigated the performance of in-situ H O\n2 2\ngeneration and As(III) oxidation during reaction at different pH. As shown in Figure 6c\nand Figure S74a, the concentration of As (III) was completely oxidized within 90 min\nat pH=3 and displayed a highest oxidation rate of 0.0527 min-1 than those at pH=7 and\npH=10. During 3 h reaction, it also exhibits a continuously increasing H O\n2 2\nconcentration at pH=3, reaching 471.5 M at 3 h, which was significantly higher than\nthat at pH=7 and pH=10 (Figures S74b and S74c).\nThese results indicated that low pH significantly enhanced in-situ H O production,\n2 2\nas the protonated environment promotes ORR to generate H O (O + 2H+ → H O ),\n2 2 2 2 2\nwhich was also seen in our response for the Comment 10 of Reviewer 1. (Nat. Commun.\n2023, 14, 5742). Concurrently, analysis of active species during the process of As (III)\noxidation reveals that H O serves as the primary active species to oxidize As (III),\n2 2\nwithout conversion into other reactive species (The specific description has been\ndisplayed in our response to your Comment 4. See your Comment 4). Therefore,\nlowering the pH efficiently produced H O through piezo-photocatalysis, thereby\n2 2\nenhancing the oxidation capacity of As(III) and accelerating the oxidation kinetics of As\n(III).\n40/46\nFigure 6 | Evaluation of environmental applications for mine wastewater treatment.\na and b, Time profiles of all CTFs in 1 h (a) and CTF-TF (b) in 3 h for heterogeneous\ninterfacial As (III) oxidation. c, The effect of different pH. d, As-containing mine\nwastewater treatment. The inset shows the photographs of wastewater during the\ndegradation process.\nFigure S74: CTF-TF-0.5 for piezo-photocatalytic As (III) oxidation at pH=3, 7 and 10.\nThe first-order kinetics model of As (III) oxidation (a). In-situ generated H O (b) and\n2 2\nthe corresponding zero-order kinetics model (c). The oxidation amount of As (III) and\nthe production and adsorption amounts of As (V) at 1 h (d).\nOur modification to the manuscript: The corresponding description was added in the\nrevised manuscript (Pages 18-19) and Supplementary Information (Figure S74).\nSummary Comments: In summary, the manuscript presents an interesting idea but\nlacks coherence in its mechanistic rationale and supporting evidence. The\nexperimental data are not sufficiently robust or consistent to substantiate the claims.\nSubstantial reorganization, additional experiments, and clearer mechanistic validation\nwould be required for the work to reach publishable quality.\nAuthor response: We highly appreciate the comments from the reviewer, and they are\nall considered in corrected manuscript. In the revised version, we further demonstrate\nour structure and claims using Solid state NMR, Time-dependent density functional\ntheory (TD-DFT) calculations, DOS calculations, GC-MS and additional extensive\nperformance testing.\nThank you very much again for your kind and appropriate comments. We are sure\nthat these comments help improve the quality of our manuscript significantly.\nSincerely yours,\nJunhao Qin\n42/46\nReviewer #3 (Remarks to the Author):\nSummary Comments: I co-reviewed this manuscript with one of the reviewers who\nprovided the listed reports. This is part of the Nature Communications initiative to\nfacilitate training in peer review and to provide appropriate recognition for Early\nCareer Researchers who co-review manuscripts.\nAuthor response: We appreciate the reviewer’s critical comments, which helped us to\nimprove the overall quality of the manuscript significantly. By following the reviewer’s\ncomments, we have revised the manuscript in a point-by-point manner. In particular,\nwe tried to add more details and clarify ambiguous claims in Reponses to Reviewer #2.\nThank you very much again for your kind and appropriate comments. We are sure\nthat these comments help improve the quality of our manuscript significantly.\nSincerely yours,\nJunhao Qin\n43/46\nReviewer #4 (Remarks to the Author):\nSummary Comments: The paper from Li et al. proposes a fluorine substituted\nmolecular organic junction catalyst for efficient hydrogen peroxide photosynthesis. By\ntuning the coordination number of the F-substituted benzene linker, spatially\nseparated oxidation-reduction centers were obtained to boost oxygen reduction and\nwater oxidation reactions for hydrogen peroxide production. Overall, the paper is well\nwritten and proposes significant advancement to this field. Therefore, it is\nrecommended for publication in Nature Communications after addressing the\nfollowing minor issues.\nAuthor response: We highly appreciate the positive comments from the reviewer, and\nthey are all considered in corrected manuscript.\n1. The authors should provide some explanation for the observed reduction in H O\n2 2\nproduction rates in real water compared to pure water.\nAuthor response: Thank you for the insightful suggestion. The reason of the lower rate\nof H O production could be attributed to due to the presence of numerous ions or\n2 2\norganic pollutant in real water. The corresponding statements are added in the revised\nmanuscript as follows:“As shown in Figure 5e, the performance of CTF-TF-0.5 in the\nphotocatalytic production of H O can still be maintained at a high level under\n2 2\ndifferent solute conditions, despite slightly lower performance than pure water due\nto the impact of a large number of ions or organics in the real water on H O\n2 2\nproduction.”\nOur modification to the manuscript: The corresponding description has been added\nin the revised manuscript (Page 14).\n2. The authors should add the important characterization data of CTF from\nSupplementary Information to main manuscript, since the innovation of this paper lies\nin catalyst design.\nAuthor response: We thank you for the reviewer’s constructive comment. The\ncorresponding important characterization data has been added to the revised\nmanuscript from Supplementary Information.\nOur modification to the manuscript: The corresponding description has been added\nin the revised manuscript, including Solid state NMR, FT-IR and Solid state EPR (Page\n8, Figure 3).\n3. The authors should explain why the peak of FTIR will blue shift as pressure increases.\nAuthor response: We appreciate the reviewer’s critical comments. Thank you very\nmuch for your professional suggestion. In the case of organic polymers, pressurization\nshortens the distance between molecules and increases intermolecular repulsive\nforces and interactions, resulting in a blue shift in the vibrational frequency of FT-IR [J.\nMol. Struc. 2008, 889, 1-11; J. Mol. Liq. 2002, 101, 149-158; J. Chem. Phys. 2002, 116,\n2928-2935]. Therefore, owning to the spatial separated redox site of in CTF-TF-0.5,\npressurization increases its molecular repulsion even more, resulting in a greater\ndegree of blue-shift of CTF-TF-0.5 relative to CTF and CTF-TF.\n44/46\n4. In-situ EPR is an important method to capture the continuous generation process of\nactive species, and thus detailed test procedures and experimental photograph should\nbe provided.\nAuthor response: We appreciate the reviewer’s professional comments. We added the\ncorresponding description in Figure S68 and Text S4. Electron paramagnetic resonance\n(EPR, Bruker Corporation, EMX nano) was used to explore the free radicals using at\nambient temperature. 100 µL DMPO was added to 5 mL reaction solution (Dimethyl\nsulfoxide (DMSO) was used as a solution to *O -, while water is used as a solution to\n2\ncapture *OH). Ultrasonic force and light were applied to the sample via an ultrasonic\ncleaner and a 300 W Xe lamp. During the reaction, solution from the reactor was\ntransferred at 20 rpm via a peristaltic pump to the EPR sample chamber for collecting\nsignals, then returned to the reactor. All the samples were measured under the same\nconditions (Mod Amp: 1.000 G, Mod Freq: 100 kHz, Res Center: 125 mm, Res Length:\n25 mm, Sweep time per sample: 30 s for offline samples and 2.5 s for samples in situ\nmeasurement ; Sample interval: 0.5 The spectra were fitting by EPR software.\nFigure S68: Photograph of in-situ EPR system for photocatalytic H O production with\n2 2\nUs.\nOur modification to the manuscript: The corresponding description has been added\nin the revised Supplementary Information (Figure S68 and Text S4).\n5. The authors should standardize the writing of all free radicals.\nAuthor response: We appreciate the reviewer’s professional comments. Thank you\nvery much for your professional suggestion. According to your suggestion, all free\nradical writing is uniformed.\nOur modification to the manuscript: The corresponding description was modified to\nthe revised manuscript and Supplementary Information.\nThank you very much again for your kind and appropriate comments. We are sure\nthat these comments help improve the quality of our manuscript significantly.\nSincerely yours,\nJunhao Qin\n46/46"}, {"round": 2, "reviewer_comments": {"reviewer_1": "The revised manuscript addressed all the raised issues satisfactorily and I have no further comments.", "reviewer_2": "We have revised both the updated version of the manuscript as well as the provided rebuttal letter and, although we\nacknowledge that the quality of the manuscript has improved, there are still two crucial points to address.\n1) In Figure 2B from the updated manuscript, authors present DFT calculations for ORR and WOR, in which the latter seems to be endergonic and thus, unfavoured for both active sites N1 and N2. Nonetheless, at figure S47, they show that for samples containing either full oxidation sites (CTF-1) or full reductive sites (CTF-TF), the H2O2 production does not seem to change dramatically, generating 0,2 and 0,15 mM for CTF-1 and CTF-TF, respectively. This has to be clarified experimentally witha\nprobe reaction (e.g. silver reduction) if the manuscript is to be evaluated for publication.\n2) When it comes to mass transport limitations, it is unclear whether reaction is occurring at the first layers (with plenty of material being\ninactive) or if the species diffuse in and out. The reason is because light could penetrate more than the reagents and the\nabsorption event could occur at places where the reagents can not access, which is certainly important for photocatalytic\napplications. I understand the time constraints but the authors should include a sentence on the manuscript mentioning\nthe likeliness of this effect.", "reviewer_3": "I co-reviewed this manuscript with one of the reviewers who provided the listed reports. This is part of the Nature Communications initiative to facilitate training in peer review and to provide appropriate recognition for Early Career Researchers who co-review manuscripts.", "reviewer_4": "The manuscript has been revised carefully according to comments and it is suitable for publication now."}, "author_response": "Reviewer #1 (Remarks to the Author):\nSummary Comments: The revised manuscript addressed all the raised issues\nsatisfactorily and I have no further comments.\nAuthor response: We appreciate for your recommendation of acceptance of this\nmanuscript.\nThank you very much again for your kind and appropriate comments.\nSincerely yours,\nJunhao Qin\n1/5\nReviewer #2 (Remarks to the Author):\nSummary Comments: We have revised both the updated version of the manuscript as\nwell as the provided rebuttal letter and, although we acknowledge that the quality of\nthe manuscript has improved, there are still two crucial points to address.\nAuthor response: We appreciate the reviewer’s critical comments, which helped us to\nimprove the overall quality of the manuscript significantly. By following the reviewer’s\ncomments, we have revised the manuscript in a point-by-point manner. In particular,\nwe tried to add more details and clarify ambiguous claims. Our responses and\nmodifications are as follows:\n1. In Figure 2B from the updated manuscript, authors present DFT calculations for ORR\nand WOR, in which the latter seems to be endergonic and thus, unfavoured for both\nactive sites N1 and N2. Nonetheless, at figure S47, they show that for samples\ncontaining either full oxidation sites (CTF-1) or full reductive sites (CTF-TF), the H O\n2 2\nproduction does not seem to change dramatically, generating 0,2 and 0,15 mM for\nCTF-1 and CTF-TF, respectively. This has to be clarified experimentally with a probe\nreaction (e.g. silver reduction) if the manuscript is to be evaluated for publication.\nAuthor response: We appreciate the reviewer’s critical comments. We fully\nunderstand your request to experimentally verify our claim regarding redox sites in\nCTF-TF-0.5 using a probe reaction (e.g., silver reduction). Here, we must first clarify\nthat neither CTF-1 nor CTF-TF exhibited discernible redox site distributions in any of\nour previous versions, and neither our textual descriptions nor experimental data\nsubstantiated this claim. We have only proposed that CTF-TF-0.5 exhibits separable\nredox site distribution: the oxidation site (triazine connecting two benzene rings and\none F-substituted benzene) and the reduction site (triazine connecting one benzene\nring and two F-substituted benzene rings) (Figure 1c). Therefore, it is inappropriate to\nstate that CTF-1 contains full oxidation sites (CTF-1) and CTF-TF contains full reductive\nsites. Note that the separable oxidation-reduction sites exists only in CTF-TF-0.5, as\npreviously demonstrated through Figures 2 and S1-S3. Consequently, conducting\nprobe experiments (e.g., silver reduction) to investigate their impact for all CTFs on\nH O production is not particularly meaningful.\n2 2\nFurthermore, we previously stated that existing techniques cannot effectively\nidentify the active sites responsible for oxidation and reduction within the same\nstructure with different redox properties in CTF-TF-0.5. The specific description has\nbeen displayed in our previous response to your Comment 9. We have confirmed the\nseparable redox sites in CTF-TF-0.5 through additional characterization and theoretical\ncomputational simulations, including solid-state NMR spectra, time-dependent\ndensity functional theory (TD-DFT) and Density of states (DOS), combined with our\nprevious HOMO-LUMO analysis and G diagram. We hope that in the future, with the\ndevelopment of the chemical discipline, more advanced in-situ experimental methods\ncan be developed to identify such active sites.\n2. When it comes to mass transport limitations, it is unclear whether reaction is\noccurring at the first layers (with plenty of material being inactive) or if the species\ndiffuse in and out. The reason is because light could penetrate more than the reagents\n2/5\nand the absorption event could occur at places where the reagents can not access,\nwhich is certainly important for photocatalytic applications. I understand the time\nconstraints but the authors should include a sentence on the manuscript mentioning\nthe likeliness of this effect.\nAuthor response: We appreciate the reviewer’s professional comments. Based on\nyour suggestion, the corresponding description has been revised as follows:\n“In addition, the mass transfer of reactants to the surface of photocatalyst is also\nan important factor affecting the reaction efficiency, which will be studied in our\nsubsequent research.”\nOur modification to the manuscript: The corresponding description was added to\nrevised manuscript (Page 10).\nThank you very much again for your kind and appropriate comments. We are sure\nthat these comments help improve the quality of our manuscript significantly.\nSincerely yours,\nJunhao Qin\n3/5\nReviewer #3 (Remarks to the Author):\nSummary Comments: I co-reviewed this manuscript with one of the reviewers who\nprovided the listed reports. This is part of the Nature Communications initiative to\nfacilitate training in peer review and to provide appropriate recognition for Early\nCareer Researchers who co-review manuscripts.\nAuthor response: We appreciate the reviewer’s critical comments, which helped us to\nimprove the overall quality of the manuscript significantly. By following the reviewer’s\ncomments, we have revised the manuscript in a point-by-point manner. In particular,\nwe tried to add more details and clarify ambiguous claims in Reponses to Reviewer #2.\nThank you very much again for your kind and appropriate comments. We are sure\nthat these comments help improve the quality of our manuscript significantly.\nSincerely yours,\nJunhao Qin\n4/5\nReviewer #4 (Remarks to the Author):\nSummary Comments: The manuscript has been revised carefully according to\ncomments and it is suitable for publication now.\nAuthor response: Thank you very much again for your kind and appropriate\ncomments.\nSincerely yours,\nJunhao Qin\n5/5"}]

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