Rahman et al. BMC Chemistry(2024) 18:135
https://doi.org/10.1186/s13065-024-01250-y

BMC Chemistry

RESEARCH

Open Access

Effect of CdS loading on the properties
and photocatalytic activity of MoS2
nanosheets
Ashmalina Rahman1, Fazlurrahman Khan2,3,4, James Robert Jennings5,6, Ai Ling Tan1, Young-Mog Kim3,4,7 andMohammad Mansoob Khan1,6*
Abstract
Molybdenum sulfide (MoS2) and modified MoS2 with different percentages of CdS (10%, 30%, and 50% CdS@MoS2)
were successfully synthesized and characterized. The photocatalytic performance of the MoS2 and CdS@MoS2 wasevaluated by degrading brilliant green (BG), methylene blue (MB), and rhodamine B (RhB) dyes under visible lightirradiation. Amongst the synthesized photocatalysts, 50% CdS@MoS2 exhibited the highest photocatalytic activity,
degrading 97.6%, 90.3%, and 75.5% of BG, MB, and RhB dyes, respectively within 5 h. The active species involvedin the degradation processes were investigated. All trapping agents inhibited BG and MB degradation to a similar
extent, indicating that all of the probed active species play an important role in the degradation of BG and MB. In
contrast, h+ and O2•− were found to be the main reactive species in the photocatalytic RhB degradation. A potential
mechanism for the photocatalytic degradation of dyes using CdS@MoS2 has been proposed. This work highlights
the potential of CdS@MoS2 as a photocatalyst for more efficient water remediation applications.
Keywords MoS2, CdS, CdS@MoS2, Photocatalysis, Trapping agents, Pollutants*Correspondence:
Mohammad Mansoob Khan
mmansoobkhan@yahoo.com; mansoob.khan@ubd.edu.bn
1
Chemical Sciences, Faculty of Science, Universiti Brunei Darussalam,Jalan Tungku Link, Gadong, BE 1410, Brunei Darussalam
2
Institute of Fisheries Science, Pukyong National University, Busan
48513, Republic of Korea
3
Marine Integrated Biomedical Technology Center, The National Key
Research Institutes in Universities, Pukyong National University,
Busan 48513, Republic of Korea
4
Research Center for Marine Integrated Bionics Technology, Pukyong
National University, Busan 48513, Republic of Korea
5
Applied Physics, Faculty of Science, Universiti Brunei Darussalam, Jalan
Tungku Link, Gadong, BE 1410, Brunei Darussalam
6
Optoelectronic Device Research Group, Universiti Brunei Darussalam,
Brunei Darussalam, Jalan Tungku Link, Gadong, BE
1410, Brunei Darussalam
7
Department of Food Science and Technology, Pukyong National
University, Busan 48513, Republic of Korea

Introduction
Photocatalysis is a promising approach for the total mineralization of organic and inorganic pollutants because
it can be performed under ambient conditions. It is also
an energy-efficient, cost-effective, and simple methodthat does not produce secondary byproducts except CO2
and H2O [1, 2]. One of the widely used methods for the
degradation of dyes and organic contaminants is thesemiconductor-based photocatalysis process [3, 4]. Thisis because semiconductor-based materials have suitableband structures, and when the material is irradiated with
an appropriate light source (where the photon energy
is greater than the band gap energy of the semiconductor), electrons (e−) and positively charged holes (h+) are
generated, which can produce superoxide (O2•−) radicals
and hydroxyl (•OH) radicals, respectively [5, 6]. These© The Author(s) 2024. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use,sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) andthe source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in thisarticle are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not includedin the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you willneed to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The
Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available
in this article, unless otherwise stated in a credit line to the data.

Rahman et al. BMC Chemistry(2024) 18:135

reactive species are responsible for the degradation oforganic dyes and other pollutants.
Semiconductors of the type MX2 are known as transition-metal dichalcogenides, where M is a transition metal
and X is a chalcogen (S, Se, or Te) [7]. These chalcogenides have recently been recognized as potentially efficientphotocatalysts, paving the way for the development of
low-cost and earth-abundant photocatalysts. Molybdenum sulfide (MoS2) is a transition-metal dichalcogenide
that has emerged as a remarkable photocatalyst for thephotocatalytic degradation of pollutants among otherchalcogenides [8, 9]. MoS2 exhibits good semiconducting properties and has a hexagonal structure similar tographene with a narrow band gap in the range of 0.9–1.9eV [10]. However, MoS2 exhibits an electron mobility of
only 217 cm2 s− 1 V− 1, which increases the e−/h+ recombination rate when irradiated with light [11]. When MoS2
is irradiated by light with photon energies greater thanor equal to the band gap energy, e− are excited from thevalance band (VB) to the conduction band (CB) and h+
are formed in the VB, as shown in equation (R1).
+−
MoS2 (ground state) −hν−→ecb (MoS2 ) + hvb (MoS2 ) (R1)

These e−/h+ may recombine (equation R2) or react withO2 (equation R3) and OH− (equation R4) to produce O2•−and •OH radicals, which subsequently react with anddegrade organic pollutants [12]. Such reactive species
will not be generated if the e−/h+ recombines rapidly, andthis will result in a reduction in the efficiency of the photocatalytic processes.
+e−cb (MoS2 ) + hvb (MoS2 ) → MoS2 (ground state) (R2)
•−
e−
(R3)
cb + O2(ads) → O2−•h+vb + OH (ads) → . OH (R4)Fast e−/h+ recombination of MoS2 can be hindered bymany approaches such as decoration with metals, nonmetal doping, metal doping, and coupling with othersemiconductors to form composites, which have been
widely and intensively attempted in recent years [1, 13–15]. The fabrication of composite heterostructures withother semiconductors is one of the most effective ways toimprove the separation of photogenerated charge carriers and hinder the recombination of these carriers. The
appropriate combination of MoS2 with other semiconductors to fabricate heterostructures can significantly
enhance the separation of photogenerated carriers andenhance its photocatalytic performance. Various MoS2based heterostructures such as MoS2/WS2 [16], MoS2/
ZnS [17] MoS2/ZnO [18] and MoS2/g-C3N4 [19] have

Page 2 of 15

been fabricated as promising materials for photocatalytic
reactions. Among these combinations, cadmium sulfide(CdS) has recently received considerable interest owing
to its suitable direct band gap of 2.4 eV [20] which canbe excited by visible photons to generate charge carriers.
CdS has been extensively used in wastewater treatment[21] organic dye degradation [22] water splitting [23, 24]
and CO2 reduction [25]. However, pristine CdS is unable
to satisfy the requirements of practical applications dueto photocorrosion and the rapid recombination of photogenerated charge carriers. Fortunately, these limitations
can be partly overcome by combining CdS with MoS2,
resulting in a material with substantially improved photocatalytic efficiency.
In this study, the photocatalytic activity of CdS@MoS2
composite heterostructure synthesized via a hydrothermal method was investigated. The effect of CdS on the
structural and optical properties of the obtained MoS2
was characterized using X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared
spectroscopy, Raman spectroscopy, UV-visible diffuse
reflectance spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, and BrunauerEmmett-Teller surface area analysis. By combining MoS2
with CdS, the recombination rate of photogenerated
carriers was significantly reduced and an enhancementin the photocatalytic degradation of three different dyeswith a low photocatalyst dosage was achieved. A further
in-depth study of the active species responsible for thedye degradation was also performed, providing insights
into the underlying degradation mechanisms.

Experimental section
Chemicals

All reagents were used without further purification. For the synthesis, ammonium heptamolybdate((NH4)6Mo7O24, 98%) as the Mo source was purchased from BDH Chemical Ltd, UK. Cadmium sulfate(CdSO4·8/3H2O, 98%) as the Cd source, and thiourea(NH2CSNH2, ≥ 99%) as the sulfur (S) source were purchased from Merck, Germany. For the photocatalytic
application tests, methylene blue (MB) was obtained
from Merck, while rhodamine B (RhB) and brilliant
green (BG) were obtained from Sigma-Aldrich. The distilled water was purified using Aquatron, England, andethanol was purchased from Duksan Pure Chemicals Co.
Ltd, South Korea. For the active species trapping experiments, isopropanol was purchased from Merck, benzoquinone was from Acros, and ethylenediaminetetraacetic
acid disodium salt dihydrate (EDTA-2Na) was purchasedfrom Fluka.

Rahman et al. BMC Chemistry(2024) 18:135

Instrumentation

Powder X-ray diffraction (XRD, MiniflexII; Rigaku,
Japan) was used to examine the crystal structure andphase purity of the synthesized materials with step sizeof 0.0262° in the range of 10 to 80°. The determination of
the chemical states and elemental compositions of thesynthesized materials was carried out using X-ray photoelectron spectroscopy (XPS, Kratos Analytical, AXIS
Nova). The XPS analytical chamber was pumped down
to ultra-high vacuum (4.6 × 10− 9 Torr) and energies
were referenced to the adventitious carbon C1s peak at
284.8 eV. The vibrational modes present in the synthesized materials were identified using Fourier transform
infrared spectroscopy (FT-IR) via the KBr pellet method.
The FT-IR spectra of these materials were recorded using
an IRspirit FTIR spectrometer (Shimadzu, Japan) in therange of 400–4000 cm− 1. Raman spectra were obtainedusing a Micro Raman Spectrometer (JASCO NRS-5100,
Japan) equipped with a 532.06 nm laser. The opticalband gap of the materials was examined using Ultraviolet-visible diffuse reflectance spectroscopy (UV-visible
DRS, Shimadzu UV-2600i, Japan). A photoluminescence(PL) study was carried out using an F-7000 Fluorescence
spectrophotometer (Hitachi High Tech, Japan) with an
excitation wavelength of 400 nm. The morphology andcrystallographic information of the synthesized materials were analyzed using field-emission transmission electron microscopy (FE-TEM) with an acceleration voltage
of 200 kV and selected area electron diffraction (SAED)
conducted with JEM-F200 (JEOL Ltd., Tokyo, Japan).
The surface area analysis of MoS2 and 50% CdS@MoS2
was measured by a surface area analyzer (Quantachrome
autosorb-iQ, Austria). For photocatalytic studies of thesynthesized materials, the experiments were carried out
in a Toption (TOPT-V) photochemical reactor with a
300 W Xe lamp as the light source (wavelength > 350 nm).
The intensity of the light at the location of the reaction
vessel was ~ 14 mW/cm2, as measured by a Thorlabs
PM100D power meter with a S401C thermal sensor.
The distance between the reaction vessels and the water
jacket surrounding the Xe lamp was 5 cm. A Shimadzu
UV-1900 UV–visible spectrophotometer was utilized tomonitor the absorbance of BG, MB, and RhB dyes over a
wavelength range of 200–800 nm.
Preparation of MoS2

MoS2 was prepared using a hydrothermal method. In atypical synthesis, 0.3309 g of (NH4)6Mo7O24 and 0.5707 gof thiourea were added into a polytetrafluoroethylene(PTFE) container filled with 20 mL of distilled water.
The mixture was then purged with N2 gas, sonicated for
5 min, and sealed in a stainless steel autoclave. The autoclave was then heated at 200 °C for 6 h and later cooled
to room temperature. The black powder product wasPage 3 of 15

collected by centrifugation and washed with distilledwater and ethanol three times. Finally, the obtained product was dried at 60 °C for 4 h.
Preparation of CdS

CdS was synthesized using a hydrothermal method. Typically, 0.1142 g of thiourea and 0.3848 g of CdSO4·8/3H2O
were dissolved in 20 mL of distilled water. The reaction solution was purged with N2 gas and sonicated for
5 min in the PTFE container. The PTFE container wasthen sealed in the stainless-steel autoclave and heatedat 200 °C for 6 h. After that, it was cooled to room temperature, and a bright yellow product was collected bycentrifugation. The product was washed three times with
distilled water and ethanol. Finally, it was dried at 60 °C
in a drying oven.
Preparation of CdS@MoS2 composites

For the synthesis of CdS@MoS2 composites, a well-dispersed and stable black suspension was prepared by sonicating 0.2 g of the synthesized MoS2 powder in a PTFE
container filled with 20 mL of H2O. To investigate theeffect of CdS loading amount on photocatalyst performance, different weight percentages of CdS from 10 to
50% were used. Appropriate amounts of CdSO4·8/3H2O
and thiourea were added into the PTFE container.
The mixture was then purged with N2 gas, sonicatedfor 5 min, and sealed in a stainless steel autoclave. The
mixture was reacted hydrothermally at 200 °C for 6 h
to obtain a series of composites. The reaction mixture
was then cooled to room temperature and the collected
CdS@MoS2 composites were washed with distilled waterand ethanol three times. The obtained CdS@MoS2 samples were labeled as 10% CdS@MoS2, 30% CdS@MoS2,
and 50% CdS@MoS2.
Photocatalytic degradation of dyes

The photocatalytic activity of the pristine MoS2, CdS,
10% CdS@MoS2, 30% CdS@MoS2, and 50% CdS@MoS2
was evaluated by degrading different dyes (BG, MB, andRhB) at room temperature under visible light irradiation.
A typical process was carried out as follows: 5 mg of synthesized materials were sonicated in 50 mL of 10 ppm
BG, MB, or RhB aqueous solution. Then, the suspension was kept stirred in the dark for 3 min to achieve theadsorption-desorption equilibrium of dye on the surfaceof the synthesized materials before exposing it to visible
light. Approximately 3 mL suspension was transferred
into a centrifuge tube every 1 h to separate the photocatalysts and the dye pollutant. The clear aliquots were analyzed using a UV–visible spectrophotometer in the rangeof 200 to 800 nm. The photocatalytic activity of synthesized pristine MoS2, CdS, 10% CdS@MoS2, 30% CdS@
MoS2, and 50% CdS@MoS2 was estimated by measuringRahman et al. BMC Chemistry(2024) 18:135

the percentage of dyes degradation using the following
relation (1):% degradation =A0 − At× 100 (1)A0where A0 denotes the initial absorbance (the absorbanceat time t = 0 h) and At denotes the absorbance of aqueous
dye solution after time t of treatment. Both A0 and At arerecorded at the absorbance maximum (λmax) of the dye.
The λmax of BG, MB, and RhB, is 620, 658, and 553 nm,
respectively.
Active species trapping experiments

To further investigate the main reactive species responsible for the photocatalytic degradation of dyes using
50% CdS@MoS2 composite, trapping experiments werecarried out in the presence of three typical active species
trapping agents: isopropanol, benzoquinone, and EDTA2Na, which are utilized as scavengers of •OH, O2•−, andh+, respectively. These trapping agents were added separately to the aqueous dye solution at the beginning of thephotocatalytic reaction. This experiment was carried out
under the same conditions as described in sub-heading“Photocatalytic degradation of dyes”.

Page 4 of 15

Results and discussions
Powder X-ray diffraction analysis

XRD was employed to study the purity, phase, and crystal
structure of the synthesized materials. The XRD patterns
of pristine MoS2, CdS, 10% CdS@MoS2, 30% CdS@MoS2,
and 50% CdS@MoS2 are shown in Fig. 1. Pristine MoS2
exhibited peaks at 2θ values of 13.9°, 32.4°, 35.7°, and57.8°, corresponding to the (002), (100), (012), and (110)planes of 2 H/3R-MoS2 (as shown in Figure S1(a)), suggesting the formation of a mixed phase with respect tothe standard diffraction peaks found in JCPDS 37-1492[26] and JCPDS 17–0744 [27]. The “2H” and “3R” prefixes indicate hexagonal and rhombohedral symmetries,
respectively and the number represents the numberof layers in the unit cell. The diffraction peaks of MoS2
are quite broad and low in intensity, indicating that the
crystallite size is very small and has relatively poor crystallinity [28, 29]. The diffraction peaks of pristine CdS
shown in Fig. 1 could be indexed to hexagonal (JCPDS
65-3414) and cubic CdS (JCPDS 65-2887). The distinct
diffraction peaks at 2θ values of 24.9°, 26.6°, 28.3°, 36.6°,
43.8°, 47.9°, and 51.9° corresponds to the (100), (002),(101), (102), (110), (103), and (201) planes were attributed to hexagonal CdS. While peaks of (111) and (200)at 2θ values of 26.6 and 30.7 correspond to the cubic
CdS as shown in Figure S1(b). The diffraction patterns

Fig. 1 XRD patterns of MoS2, CdS, 10% CdS@MoS2, 30% CdS@MoS2, and 50% CdS@MoS2

Rahman et al. BMC Chemistry(2024) 18:135

of the CdS@MoS2 composites exhibited peaks characteristic of MoS2 and CdS. As the loading amount of CdS
increases from 10 to 50%, it is observed that the diffraction peaks of CdS become sharper and the diffraction
peaks of MoS2 become weaker. Moreover, for 50% CdS@
MoS2, additional diffraction peaks located at 24.6°, 26.5°,
28.3°, 36.7°, 43.8°, 47.9°, and 51.9° are observed, which
can be ascribed to the (100), (002), (101), (102), (110),(103), and (201) planes of hexagonal wurtzite CdS [30].
The overlapped peak centered at 26.5° and the presenceof a weak peak at 30.7° can be assigned as the (111) and(200) planes of cubic CdS, respectively, which implies
that the obtained 50% CdS@MoS2 material also consistedof a mixed phase of hexagonal and cubic CdS [31]. These
results indicate that CdS was successfully loaded onto thesurface of MoS2.
X-ray photoelectron spectroscopy

The oxidation states and elemental composition of MoS2
and 50% CdS@MoS2 were determined using XPS. In
Fig. 2(a), the XPS survey reveals the presence of Mo, S,
and adventitious C elements for pristine MoS2, and thesame elements were also observed in the 50% CdS@
MoS2 with the addition of Cd indicating the co-existenceof MoS2 and CdS in the composite [32]. These results
corroborate the high purity of all samples corresponding to their XRD. For pristine MoS2, the characteristic
peaks for Mo 3d3/2 and Mo 3d5/2 were visible as a doublet at 2315 eV and 228.3 eV which indicated the presence of Mo4+. Moreover, the Mo 3d spectra of 50% CdS@
MoS2 display two peaks at 230.2 and 227.0 eV assigningto Mo4+ 3d3/2 and Mo4+ 3d5/2. It can also be observedthat the peaks are shifting to lower binding energy positions (Fig. 2(b)). Moreover, the peak centered at 224 eV
ascribed to S 2s is also observed [33]. The binding energy
shifts reflect changes in the electronic structures of theas-synthesized materials, further showing the strong
interaction between MoS2 and CdS [30, 34–36]. As
shown in Fig. 2(c) the peak located at 37.1 and 35.1 eV
corresponds to the Mo 4p peak of MoS2 and 50% CdS@
MoS2, respectively.
The spectrum of S 2p of pristine MoS2 (Fig. 2(d)) indicates that the peak can be deconvoluted into two peaks,
one located at 162.4 and the other at 161.2 eV with anenergy difference of 1.2 eV. Meanwhile, the binding energies of S 2p of 50% CdS@MoS2 are located at 161.0 and
159.8 eV with the same energy difference of 1.2 eV. Thesepeaks can be assigned to the typical S 2p1/2 peaks and S
2p3/2 of S2− in the as-synthesized materials. As seen in
Fig. 2(e) of 50% CdS@MoS2, two characteristic peaks
centered at the binding energy of 410.2 and 403.5 eV correspond to Cd 3d5/2 and Cd 3d3/2, respectively. The binding energy values and the splitting energy of 6.75 eV areconsistent with the reported results of Cd2+ in CdS. The

Page 5 of 15

typical C 1s spectra shown in Fig. 2(f ) were derived fromthe XPS instrument itself. Thus, the above XPS results
further confirmed the formation of the CdS@MoS2
composite.
Fourier transform infrared spectroscopy

The presence of different vibrational modes of the synthesized materials was examined by FT-IR spectroscopy.
Figure 3(a) shows the FT-IR spectra of MoS2, CdS, 10%
CdS@MoS2, 30% CdS@MoS2 and 50% CdS@MoS2. The
FTIR of MoS2 showed that the bands at 463 and 913 cm− 1
can be ascribed to the Mo-S and S-S bonds, respectively[18, 37, 38]. The band centered around 1390 cm− 1 canbe ascribed to the C-N vibration of thiourea [39]. The
bands located at 622, 1128, 1401, and 1633 cm− 1 canbe attributed to the characteristic IR absorption of the
Cd–S bond, confirming the formation of CdS [1, 32]. For
the FT-IR spectrum of CdS, the broad band centered at3307 cm− 1 can be assigned to the O–H stretching vibration of the adsorbed H2O from the atmosphere. A weakband at 463 cm− 1 corresponding to the Mo-S stretchingvibration can also be observed in the spectra of all CdS@
MoS2 composites. The FT-IR spectra of 10% CdS@MoS2,
30% CdS@MoS2, and 50% CdS@MoS2 exhibited similar
Cd-S bands at approximately 925 and 1633 cm− 1. Thisconfirms the presence of both MoS2 and CdS. Thus, FTIR
also validates the successful loading of CdS onto MoS2.
Raman spectroscopy

Raman spectroscopy was used to determine the presence of optical phonon vibrations in MoS2, CdS, 10%
CdS@MoS2, 30% CdS@MoS2, and 50% CdS@MoS2. From
Fig. 3(b), the two peaks observed at 372 and 402 cm− 1
were attributed to the E12g and A1g modes of MoS2 [40].
The two identified phonon modes in MoS2 are E12g and
A1g which correspond to in-plane opposite vibrationsof molybdenum/sulfur atoms and out-of-plane vibrations of sulfur atoms, respectively [41]. Between the two
noticeable peaks, there is a 30 cm− 1 difference in thefrequency [42]. In Figure S2, pristine CdS exhibited two
characteristic peaks at 292 and 589 cm− 1, corresponding to the hexagonal phase of CdS [33]. Moreover, theRaman active MoS2 peak at 403 cm− 1 with low intensity
was also observed in 10% CdS@MoS2, 30% CdS@MoS2,
and 50% CdS@MoS2 composites. There were two additional Raman active peaks centered at 292 and 589 cm− 1
observed in 10% CdS@MoS2, 30% CdS@MoS2, and 50%
CdS@MoS2 which could be attributed to the longitudinal
optical (LO) mode of the hexagonal CdS, 1LO and 2LO
respectively. The Raman spectra of the CdS@MoS2 composites showed the characteristic features of both MoS2
and CdS. Thus, these results also confirm the successfulformation of CdS, MoS2, and CdS@MoS2 composites.

Rahman et al. BMC Chemistry(2024) 18:135

Fig. 2 XPS spectra of MoS2 and 50% CdS@MoS2: (a) survey scan, (b) Mo 3d, (c) Mo 4p, (d) S 2p, (e) Cd 3d, and (f) C 1s

Page 6 of 15

Rahman et al. BMC Chemistry(2024) 18:135

Page 7 of 15

Fig. 3 (a) FT-IR spectra and (b) Raman spectra of MoS2, CdS, 10% CdS@MoS2, 30% CdS@MoS2, and 50% CdS@MoS2

Fig. 4 (a) Tauc plots constructed from Kubelka–Munk transformed diffuse reflectance spectra and (b) PL spectra of MoS2, CdS, 10% CdS@MoS2, 30%
CdS@MoS2, and 50% CdS@MoS2

UV-visible diffuse reflectance spectroscopy

UV-vis DRS spectroscopy was employed to determine
the optical properties of pristine MoS2, CdS, and CdS@
MoS2 composites with different loading amounts of CdS(from 10 to 50%). Due to their black nature, the pristine MoS2 exhibited a broad absorption peak instead ofa sharp absorption peak in the UV-visible region. Liu etal. reported similar absorption spectra of MoS2 [20]. For
pristine CdS, the absorption spectrum has a clear onset
around 520 nm, corresponding to a band gap energy of
2.4 eV. In contrast, pristine MoS2 exhibited a narrow
band gap energy of 1.03 eV. Figure S3 shows absorbance(computed as the negative logarithm of the reflectance)
spectra of pristine MoS2, CdS, 10% CdS@MoS2, 30%
CdS@MoS2, and 50% CdS@MoS2. The difference in theabsorption properties of the as-synthesized materials is
also reflected in the change of their color (see the inset
of Fig. 4).

The effective band gaps of 10% CdS@MoS2, 30% CdS@
MoS2, and 50% CdS@MoS2 were calculated by constructing Tauc plots from Kubelka–Munk transformed diffuse
reflectance data, as shown in Fig. 4(a). The direct bandgaps of 10% CdS@MoS2, 30% CdS@MoS2, and 50% CdS@
MoS2 were estimated to be 2.0, 2.2, and 2.3 eV, respectively. As the CdS content increases, the band gap energy
of CdS@MoS2 gradually increases from 2.0 eV to 2.3 eV.
To investigate the ability of these materials to harvest
visible light energy (due to their narrow band gaps) andeffectively utilize the photogenerated charge carriers, thephotocatalytic degradation of various dyes was studied,and the results were presented in Table 1 and discussed
in Sect. “Photocatalytic degradation of dyes”.
Photoluminescence spectroscopy

PL spectra were acquired to study the recombination andinterfacial transfer of charge carriers in the synthesizedmaterials. The PL spectra (excitation wavelength 400 nm)

Rahman et al. BMC Chemistry(2024) 18:135

Table 1 The effective band gap energy and photocatalytic
degradation efficiency of MoS2, CdS, 10% CdS@MoS2, 30% CdS@
MoS2, and 50% CdS@MoS2
Synthesizedmaterials

Band gap
energy
(eV)

MoS2
CdS
10% CdS@MoS2
30% CdS@MoS2
50% CdS@MoS2

1.03
2.40
2.00
2.20
2.30

Photocatalytic degradation (%)
Brilliant
MethyRhodagreen
lene blue mine B
45.9 ± 1.50 42.3 ± 5.96 30.0 ± 2.37
88.9 ± 4.13 26.7 ± 0.85 31.5 ± 2.29
46.3 ± 7.46 33.9 ± 1.42 25.6 ± 2.65
34.6 ± 1.50 23.0 ± 2.26 20.5 ± 0.53
97.6 ± 1.74 90.3 ± 3.79 75.5 ± 7.78

of MoS2, CdS, 10% CdS@MoS2, 30% CdS@MoS2, and
50% CdS@MoS2 are shown in Fig. 4(b). The pristine CdS
exhibits two PL peaks at 510 and 528 nm, while the pristine MoS2 exhibits no detectable PL peaks over the same
wavelength range. In contrast to pristine CdS, the spectraof the CdS@MoS2 composites only exhibit a single emission peak at 506 nm. The strong quenching of the 528 nm
PL peak in the composites indicates reduced recombination in the CdS, most likely due to charge transfer fromCdS to MoS2. Compared to other composites, 10% CdS@
MoS2 exhibited the lowest PL intensity possibly due tothe least amount of CdS loaded onto the MoS2 surface.
Whereas 30% CdS@MoS2 showed the highest PL intensity which generally reflects rapid recombination of
charge carriers and usually results in lower photocatalytic activity. Moreover, the 50% CdS@MoS2 displayed areduced PL intensity compared to 30% CdS@MoS2, indicating the effective separation of photo-induced charge
carriers at the CdS/MoS2 interface.

Fig. 5 TEM images of (a) MoS2 and (b) 50% CdS@MoS2 composite

Page 8 of 15

Transmission electron microscopy

The morphologies of the as-synthesized pristine MoS2
and 50% CdS@MoS2 were investigated by TEM, as
shown in Fig. 5. As can be seen in Fig. 5(a), the TEM
image of pristine MoS2 consists of thin nanosheets. Afterthe modification of MoS2 with 50% CdS, the morphology
remained mostly unchanged with some agglomeration.
In addition, HR-TEM was also used to further explore
the nanostructures of MoS2 and 50% CdS@MoS2. In Figure S4(a), the interplanar spacing of 0.27 nm observedin the MoS2 high-resolution TEM (HR-TEM) could be
ascribed to the (101) plane of 3R-MoS2 and (100) planeof 2 H-MoS2 [43, 44]. While the HR-TEM of 50% CdS@
MoS2, as shown in Figure S4(b), revealed the interplanar
spacing of 0.32 nm could be assigned to (101) plane ofhexagonal CdS and 0.34 nm could be assigned to (111)plane of cubic CdS. Additionally, the presence of 0.27 nm
spacing in the HR-TEM of 50% CdS@MoS2 confirms
the successful formation of CdS@MoS2 composites. The
selected area electron diffraction (SAED) shown in Figure S5 and Figure S6 confirms the polycrystalline natureof the MoS2 and 50% CdS@MoS2. Combined with the
XRD and XPS characterization, these results confirm theformation of and close contact between CdS and MoS2,
which is advantageous for interfacial charge separation.
Brunauer-Emmett-Teller surface area analysis

The surface area of MoS2 and 50% CdS@MoS2 was analyzed from N2 adsorption/desorption isotherm as shownin Figure S7 and the corresponding multipoint BET plot(inset graph in Figure S7). The adsorption/desorption

Rahman et al. BMC Chemistry(2024) 18:135

isotherms of the synthesized materials are the characteristic IV curves with prominent H3-type hysteresis
loops, illustrating the synthesized materials exhibited
porous structures [45]. The MoS2 exhibited a surface areaof 55.421 m2/g. With the introduction of 50% CdS onto
MoS2, the surface area increases to 63.542 m2/g. Thiscan reasonably explain why the formation of CdS@MoS2
composite is beneficial in increasing the surface area andthe number of active sites.

Photocatalytic degradation of dyes
The photocatalytic activity of pristine CdS, MoS2, andCdS@MoS2 composites with various CdS percentages(10, 30, and 50%) was investigated by monitoring thedegradation of BG, MB, and RhB under visible light irradiation. In order to study the stability of the dyes, the dyesolutions were first subjected to a photolysis process.
This was also carried out as a positive control experiment. The results show that only 4%, 3%, and 6% degradation were observed in aqueous BG, RhB, and MB blankdyes (in the absence of photocatalysts). This means thatthe photocatalyst is required for the acceleration of thephotocatalytic reaction.
From the photocatalytic degradation experiment, it
was found that pristine CdS degraded about 88.9% ±
4.13% of BG within 5 h while pristine MoS2 showed
high adsorption and poor photocatalytic activity (45.9%± 1.50%) as shown in Fig. 6(a). Using different percentages of CdS, the photocatalytic performance of MoS2 wasremarkably enhanced. The average degradation percentages were found to be 46.3% ± 7.46%, 34.6% ± 1.50%, and97.6% ± 1.74% for 10% CdS@MoS2, 30% CdS@MoS2 and
50% CdS@MoS2, respectively. The photocatalytic degradation of MB in aqueous solution under visible lightirradiation using MoS2, CdS, 10% CdS@MoS2, 30% CdS@
MoS2, and 50% CdS@MoS2 were shown in Fig. 6(c).
Both pristine CdS and MoS2 showed poor photocatalytic
activity with only 26.7% ± 0.85% and 42.3% ± 5.96% degradation of MB, respectively. The photocatalytic performance of MoS2 was remarkably enhanced as the amountof CdS loading increased from 10 to 50% and the average degradation percentages were about 33.9% ± 1.42%,
23.0% ± 2.26%, and 90.3% ± 3.79% for 10% CdS@MoS2,
30% CdS@MoS2, and 50% CdS@MoS2, respectively. The
photocatalytic activities of MoS2, CdS, 10% CdS@MoS2,
30% CdS@MoS2, and 50% CdS@MoS2 were also evaluated by degrading RhB in aqueous solution under visible light irradiation as shown in Fig. 6(e). Both pristine
CdS and MoS2 showed poor photocatalytic activity with
only 31.5% ± 2.29%, and 30.0% ± 2.37% degradation of
RhB, respectively. Using different percentages of CdS,
the photocatalytic degradation performance of MoS2
was remarkably enhanced and the average photocatalytic degradation percentages were about 25.6% ± 2.65%,

Page 9 of 15

20.5% ± 0.53%, and 75.5% ± 7.78% for 10% CdS@MoS2,
30% CdS@MoS2, and 50% CdS@MoS2, respectively.
Based on these results, it can be observed that the photocatalytic activity of MoS2 increases and then decreases
when the amount of CdS loaded increases from 10
to 30% for BG, MB, and RhB dyes. This is owing to an
inadequate amount of CdS being loaded onto MoS2 inboth 10% and 30% CdS@MoS2 composites, indicating
the importance of CdS in the composites. On the other
hand, 50% CdS@MoS2 exhibited the highest photocatalytic efficiency against BG, MB, and RhB dyes comparedto the other synthesized materials. This may be ascribedto the high loading amount of CdS on the MoS2 surface. Figure 6(b, d, and f ) present C/C0 vs. time graphsthat provide a clearer understanding of the effect of CdS
loading on the photocatalytic performance of MoS2 forthe degradation of BG, MB, and RhB dyes, respectively.
The C/C0 metric is calculated as the ratio of the absorbance intensity at t = 0, 1, 2, 3, 4, and 5 h to the absorbance intensity at t = 0 h. Based on these plots, it can beobserved that as time progresses, the C/C0 decreases. The
photocatalytic activity of 50% CdS@MoS2 against BG,
MB, and RhB dyes was found to be substantially higher
than those of pristine MoS2, CdS, 10% CdS@MoS2 and
30% CdS@MoS2.
The first-order rate constants for the degradation of BG,
MB, and RhB dyes by 50% CdS@MoS2 were estimatedto be 0.0145, 0.0087, and 0.0038 min− 1, respectively, as
shown in Figure S8. The low photocatalytic degradation
activity of MoS2 could be attributed to the rapid recombination of e−/h+ pairs. The superior photocatalytic activityof 50% CdS@MoS2 is due to the presence of CdS on thesurface of MoS2 which may facilitate the separation andtransfer of the photogenerated electrons and holes effectively, hence, better photocatalytic degradation efficiency.
The improved photocatalytic activity of 50% CdS@MoS2
may also be due to its high surface area (63.542 m2/g)
and close interfacial contact, which enables the dye molecules to adsorb onto the photocatalyst (adsorption is aprerequisite for photocatalytic reactions [33]) and able todegrade these dyes upon light irradiation.
Based on these results, it is also observed that 50%
CdS@MoS2 could degrade more BG than MB and RhB
dye. In general, photocatalytic degradation is strongly
related to the adsorption affinity of dyes on the surfaceof the photocatalyst [33]. This indicates that BG dye has ahigher affinity towards 50% CdS@MoS2 when comparedto MB and RhB under the same conditions. This can beevident during the adsorption-desorption equilibrium at
0 h in which about 34.7%, 23.8%, and 16.5% of BG, MB,
and RhB could be adsorbed on 50% CdS@MoS2, respectively. Thus, high adsorption leads to more interaction
between dyes with the active sites of the 50% CdS@MoS2,
resulting in better photocatalytic degradation. Table 2

Rahman et al. BMC Chemistry(2024) 18:135

Page 10 of 15

Fig. 6 Photocatalytic efficiency and C/C0 plots of MoS2, CdS, 10% CdS@MoS2, 30% CdS@MoS2, and 50% CdS@MoS2 for (a, b) BG (c, d) MB, and (e, f) RhB
degradation under visible light irradiation, respectively

Rahman et al. BMC Chemistry(2024) 18:135

Page 11 of 15

Table 2 Previous studies on the photocatalytic degradation of dyes using CdS/MoS2-based composites
Synthesizedmaterials

Source oflight

Pollutant used

ZnS/Mn-CdS/
MoS2/TiO2
MoS2/CdS/
Bi2MoO6300 W of Xe
lamp
300 W Xelamp

10 ppm of methyl orange(100 mL)
10 ppm of rhodamine B, methyl
orange, methylene blue, and bromophenol blue (50 mL)

CdS@MoS2

500
W Xe lamp
300 W Xelamp

20 ppm of methylene blue
(50 mL)10 ppm of brilliant green, methylene
blue, and rhodamine B (50 mL)

CdS@MoS2

compares photocatalytic activity of the synthesized CdS@
MoS2 with previously reported work. Amongst them, thehydrothermally synthesized CdS@MoS2 reported by Liu
and co-workers exhibited nearly the same activity [20].
However, in their study, they used a higher wattage oflight (500 W) and only one type of dye (MB) was studied.
On the other hand, in the present study, three different
dyes were used to highlight the selectivity and efficiencyof the synthesized CdS@MoS2 with a minimal dosage ofcatalyst (0.1 mg/mL) under irradiation by a lower wattage
light source (300 W). Moreover, unlike these previous
studies, here we report an in-depth study of the active
species responsible for dye degradation through suitabletrapping experiments to better understand the underlying mechanisms driving the degradation of BG, MB, andRhB dyes.
Determination of the main reactive species with different
scavengers

Active species trapping experiments were performed toget deeper insight into the primary and secondary species responsible for the degradation of BG, MB, and RhB
dyes during the photocatalysis process using 50% CdS@
MoS2 composite. Different trapping agents (scavengers)
including isopropanol, benzoquinone, and EDTA-2Na
were used in separate experiments as scavengers of •OH,
O2•−, and h+, respectively, in the photocatalytic degradation process of the different dyes [40, 41]. Higher inhibition (lower percentage degradation) in the presence ofa trapping agent implies higher importance of the corresponding active species in the degradation process.
It was observed that when no scavenger was used, thedegradation efficiency of 50% CdS@MoS2 was 97.6% ±1.74%, 90.3% ± 3.80%, and 75.5% ± 7.78% for BG, MB, and
RhB, respectively (Fig. 7(a − c)). As depicted in Fig. 7(a)for 50% CdS@MoS2, the presence of isopropanol inhibits BG degradation, resulting in a drop in degradation

Amount ofphotocatalyst
used
20 mg
(0.2 mg/mL)
30 mg(0.6 mg/mL)

Rate constant(min− 1)Results

Ref.

Not mentioned

98% in 100 min[49]

0.0256[50]

4 mg(0.08 mg/mL)
5 mg(0.1 mg/mL)

0.105

Rhodamine B: 70.5%, Methyl
orange:80.3%, Methylene
blue: 96.0%, and bromophenol blue: 99.1% in 120 min
80% in 30 min
Brilliant green: 97.6%
Methylene blue: 90.3%, andRhodamine B: 75.5% in 5 h

This
work

Brilliant green:
0.0145
Methylene blue:
0.0087and Rhodamine
B: 0.0038[20]

efficiency to 84.4% ± 3.02%. After the addition of benzoquinone and EDTA-2Na, the photocatalytic efficiency of
50% CdS@MoS2 decreased to 75.2% ± 6.20% and 77.7% ±0.79%, respectively. Similarly, for the degradation of MB
as shown in Fig. 7(b), both benzoquinone and EDTA2Na can inhibit the photocatalytic efficiency of MB degradation by 50% CdS@MoS2 from 90.3% ± 3.80–63.3% ±5.51% and 62.5% ± 3.06%, respectively. Moreover, in thepresence of isopropanol, 50% CdS@ MoS2 could degrade
about 67.0% ± 3.10% of MB. Based on these inhibitions,
it can be observed that the difference between trapping
agents was less pronounced for BG and MB dyes, but on
average isopropanol was still less inhibiting than EDTA2Na and benzoquinone. However, it is different in thecase of RhB degradation. As shown in Fig. 7(c), the photocatalytic efficiency of RhB degradation by 50% CdS@
MoS2 decreased from 75.5% ± 7.78% in the absence ofscavenger to 66.6% ± 1.70% in the presence of isopropanol. In comparison, the photocatalytic RhB degradation
efficiency decreased to 37.1% ± 4.33% and 29.5% ± 0.75%
after the addition of benzoquinone and EDTA-2Na,
respectively. Based on the slight influence of isopropanolon the degradation of RhB, it can be concluded that •OH
was not the main active species during the photocatalytic
degradation of RhB. Contrarily, the obvious inhibitionof benzoquinone and EDTA-2Na in the RhB degradation illustrates that h+ and O2•− were the main reactive
species during the photocatalytic dye degradation process. Overall, the various active species contribute in theorder h+ > O2•− > •OH for the degradation of RhB. Thus,
it can be inferred that h+, O2•−, and •OH are all generated in the photocatalytic process using 50% CdS@MoS2.
Additionally, the synergistic effect between the different active species can greatly enhance the photocatalytic
performance.

Rahman et al. BMC Chemistry(2024) 18:135

Page 12 of 15

Fig. 7 Photocatalytic activity of 50% CdS@MoS2 with different trapping agents to determine the main reactive species responsible for the degradationof (a) BG, (b) MB, and (c) RhB dye

Possible photocatalytic mechanism for dye degradation

Based on the above results, the mechanism for photocatalytic degradation of different dyes using CdS@MoS2
was proposed and is shown in Fig. 8. Based on the literature, MoS2 is assumed to have ECB = 0.04 V and EVB =1.36 V, while CdS has ECB = -0.63 V and EVB = 1.77 V [46].
Upon visible light irradiation, CdS simultaneously generates e− and h+, in which photogenerated e− are excited
to the CB, leaving behind h+ in the VB. Next, the photogenerated e− migrates to the CB of MoS2 to take partin the reduction process. The effective charge separation
contributes to the improved photocatalytic activity of
CdS@MoS2. The photogenerated e− can reduce the dye
directly or react with electron acceptors adsorbed on
the surface of the photocatalyst, such as dissolved O2 inwater, which is reduced it to O2•−. On the other hand, thephotogenerated h+ can react with H2O or OH− species,

oxidizing them into •OH radicals, or directly oxidizing
the organic dyes to CO2 and H2O, which are harmlessend products [47, 48]. Based on the active species trapping study, both benzoquinone and EDTA-2Na showed
the highest inhibitions when compared to no scavenger
for all three dyes. However, there is no significant difference between the inhibition caused by benzoquinone and
EDTA-2Na, which indicates that both O2•− and h+ playequally important roles in the photocatalytic degradation
process. Moreover, in the case of RhB degradation, isopropanol shows the lowest inhibition, implying the least
importance of •OH taking part in the RhB degradation.

Conclusion
In this study, MoS2, CdS, 10% CdS@MoS2, 30% CdS@
MoS2, and 50% CdS@MoS2 were successfully synthesized using a hydrothermal method. The XRD patterns

Rahman et al. BMC Chemistry(2024) 18:135

Page 13 of 15

Fig. 8 Proposed mechanism for the photocatalytic degradation of different dyes using CdS@MoS2

of pristine MoS2 and CdS exhibited mixed-phase crystal
structures, while the XRD patterns of CdS@MoS2 composites revealed both the presence of 3R/2H MoS2 and amixed phase of hexagonal and cubic CdS. The formationof the synthesized MoS2, CdS, and CdS@MoS2 composites was also confirmed by FT-IR analysis. The effective
optical band gap of MoS2 increases from 1.03 eV to 2.3 eV
as the CdS content increases to 50%. The photocatalytic
degradation activity of these materials was investigatedunder visible light irradiation. Based on the results, 50%
CdS@MoS2 exhibited the highest photocatalytic activity for the degradation of BG, MB, and RhB dyes undervisible light irradiation. The active species trapping
study shows no significant difference between the trapping agents in the inhibition of BG and MB degradation.
However, for RhB degradation, it can be concluded thath+ and O2•− are the main active species involved in thephotocatalytic process under visible light irradiation. A
possible mechanism for the photocatalytic degradation of
the dyes using CdS@MoS2 was also proposed. These findings are expected to assist in the design and constructionof highly efficient photocatalysts for the large-scale degradation of dye effluents.

Author contributions
AR: Methodology, investigation, data curation, writing – original draft. FK:
Methodology, data curation, review and editing. JRJ: Supervision, writing,review & editing. ALT: Supervision, writing, review & editing. YMK: Resources,
funding, & formal analysis. MMK: Supervision, conceptualization, funding
acquisition, writing, review & editing.
Funding
This research was funded by Universiti Brunei Darussalam through grants
UBD/RSCH/1.4/FICBF(b)/2021/035 and UBD/RSCH/1.4/FICBF(b)/2023/059
and was also supported by the Basic Science Research Program through the
National Research Foundation (NRF) of Korea grant funded by the Ministry of
Education (2021R1A6A1A03039211 and 2022R1A2B5B01001998).
Data availability
No datasets were generated or analysed during the current study.

Declarations
Competing interests
The authors declare no competing interests.
Ethics approval and consent to participate
Not applicable.
Consent for publication
Not applicable.
Received: 24 December 2023 / Accepted: 15 July 2024

Supplementary Information

The online version contains supplementary material available at https://doi.
org/10.1186/s13065-024-01250-y.
Supplementary Material 1
Acknowledgements
AR, JRJ, ALT, and MMK would like to acknowledge all the supports provided by
Universiti Brunei Darussalam, Brunei Darussalam for research.

References
1. Rajendran R, Varadharajan K, Jayaraman V. Fabrication of tantalum doped CdS
nanoparticles for enhanced photocatalytic degradation of organic dye undervisible light exposure. Colloids Surf Physicochem Eng Asp. 2019;580:123688.
https://doi.org/10.1016/j.colsurfa.2019.123688.
2. Khan MM, Pradhan D, Sohn Y. Springer series on polymer and composite
materials nanocomposites for visible light-induced photocatalysis, n.d. http://
www.springer.com/series/13173.
3. Rahman A, Khan MM. Chalcogenides as photocatalysts. New J Chem.
2021;45:19622–35. https://doi.org/10.1039/D1NJ04346C.

Rahman et al. BMC Chemistry

4.
5.

6.
7.
8.

9.
10.

11.
12.
13.

14.

15.

16.

17.

18.

19.

20.
21.

22.
23.

(2024) 18:135

Khan MM, Adil SF, Al-Mayouf A. Metal oxides as photocatalysts. J Saudi Chem
Soc. 2015;19:462–4. https://doi.org/10.1016/j.jscs.2015.04.003.
Opoku F, Govender KK, van Sittert CGCE, Govender PP. Recent progress in thedevelopment of semiconductor-based photocatalyst materials for applications in photocatalytic water splitting and degradation of pollutants. Adv
Sustain Syst. 2017;1:1700006. https://doi.org/10.1002/adsu.201700006.
Mohammad M, Khan. Theoretical concepts of photocatalysis. Elsevier; 2023.
https://doi.org/10.1016/C2021-0-01798-3.
Manzeli S, Ovchinnikov D, Pasquier D, Yazyev Ov, Kis A. 2D transition metal
dichalcogenides. Nat Rev Mater. 2017;2:17033. https://doi.org/10.1038/
natrevmats.2017.33.
Thomas N, Mathew S, Nair KM, O’Dowd K, Forouzandeh P, Goswami A,
McGranaghan G, Pillai SC. 2D MoS2: structure, mechanisms, and photocatalytic applications. Mater Today Sustain. 2021;13:100073. https://doi.
org/10.1016/j.mtsust.2021.100073.
Rahman A, Jennings JR, Tan AL, Khan MM. Molybdenum disulfide-based
nanomaterials for visible-light-induced photocatalysis. ACS Omega.
2022;7:22089–110. https://doi.org/10.1021/acsomega.2c01314.
Vaizoğullar Aİ. Ternary CdS/MoS2/ZnO photocatalyst: synthesis, characterization and degradation of Ofloxacin under visible light irradiation. J
Inorg Organomet Polym Mater. 2020;30:4129–41. https://doi.org/10.1007/
s10904-020-01563-0.
Ryou J, Kim Y-S, KC S, Cho K. Monolayer MoS2 bandgap modulation by dielectric environments and tunable bandgap transistors. Sci Rep. 2016;6:29184.
https://doi.org/10.1038/srep29184.
Md. Ahmaruzzaman V, Gadore. MoS2 based nanocomposites: an excellent
material for energy and environmental applications. J Environ Chem Eng.
2021;9:105836. https://doi.org/10.1016/j.jece.2021.105836.
Zhao T, Xing Z, Xiu Z, Li Z, Yang S, Zhou W. Oxygen-doped MoS2 Nanospheres/CdS Quantum Dots/g-C3N4 nanosheets super-architectures forprolonged charge lifetime and enhanced visible-light-driven photocatalytic
performance. ACS Appl Mater Interfaces. 2019;11:7104–11. https://doi.
org/10.1021/acsami.8b21131.
Zhou M, Cheng L, Chen Z, Chen L, Ma Y. CdSe QDs@MoS2 nanocomposites
with enhanced photocatalytic activity towards ceftriaxone sodium degradation under visible-light irradiation. J Alloys Compd. 2021;869:159322. https://doi.org/10.1016/j.jallcom.2021.159322.
Hou S, Wang P, Nie Y, Guo Y, Ma Q. A novel work function tuning strategybased ECL sensor with sulfur dots and au NP@MoS2 nanosheet heterostructure for triple-negative breast cancer diagnosis. Chem Eng J.
2022;446:136906. https://doi.org/10.1016/j.cej.2022.136906.
Pesci FM, Sokolikova MS, Grotta C, Sherrell PC, Reale F, Sharda K, Ni N,
Palczynski P, Mattevi C. MoS2/WS2 heterojunction for photoelectrochemical water oxidation. ACS Catal. 2017;7:4990–8. https://doi.org/10.1021/
acscatal.7b01517.
Gusain R, Kumar N, Opoku F, Govender PP, Ray SS. MoS2 Nanosheet/ZnS
composites for the visible-light-assisted photocatalytic degradation of oxytetracycline. ACS Appl Nano Mater. 2021;4:4721–34. https://doi.org/10.1021/
acsanm.1c00330.
Ritika M, Kaur A, Umar S, Mehta S, Singh S, Kansal H, Fouad O, Alothman.
Rapid solar-light driven superior photocatalytic degradation of methylene
blue using MoS2-ZnO heterostructure Nanorods Photocatalyst. Materials.
2018;11:2254. https://doi.org/10.3390/ma11112254.
He Y, Ma Z, Junior LB. Distinctive binary g-C3N4/MoS2 heterojunctions
with highly efficient ultrasonic catalytic degradation for levofloxacin andmethylene blue. Ceram Int. 2020;46:12364–72. https://doi.org/10.1016/j.
ceramint.2020.01.287.
Liu X, Li J, Yao W. CdS@MoS2 hetero-structured nanocomposites arehighly effective photo-catalysts for organic dye degradation. ACS Omega.
2020;5:27463–9. https://doi.org/10.1021/acsomega.0c03968.
Zou M, Tan C, Zhang Y, Hu J, Ma Z, Yuan Z, Zhang L, Wu M, Zhou H. Exploring
the potential of flexible CdS/ZnO/Polyurethane nanocomposite membrane
for wastewater remediation. J Environ Chem Eng. 2023;11:110135. https://doi.
org/10.1016/j.jece.2023.110135.
Zhang Z, Dong X, Wang Y, Zheng N, Ma H, Zhang X. Co9S8/CdS heterostructures as efficient photocatalysts for degradation of organic pollutant. Ceram
Int. 2023;49:25207–15. https://doi.org/10.1016/j.ceramint.2023.05.053.
Wang T, Guo C, Zhang L, Cao X, Niu Y, li J, Akram N, Wang J. Effect of different
CdS morphologies on photocatalytic water splitting performance of CdS@
ZIF-67 composites. Int J Hydrogen Energy. 2023. https://doi.org/10.1016/j.
ijhydene.2023.03.111.

Page 14 of 15

24. Khan MM, Rahman A. Chalcogenides and chalcogenide-based heterostructures as photocatalysts for water splitting. Catalysts. 2022;12:1338. https://doi.
org/10.3390/catal12111338.
25. Lee D-E, Mameda N, Reddy KP, Abraham BM, Jo W-K, Tonda S. Bifunctional
S-scheme hybrid heterojunction comprising CdS nanorods and BiOIO3nanosheets for efficient solar-induced antibiotic degradation and highlyselective CO2 reduction. J Mater Sci Technol. 2023;161:74–87. https://doi.
org/10.1016/j.jmst.2023.03.024.
26. Wang Z, Ma L, Chen W, Huang G, Chen D, Wang L, Lee JY. Facile synthesisof MoS2/graphene composites: effects of different cationic surfactants on
microstructures and electrochemical properties of reversible lithium storage.
RSC Adv. 2013;3:21675. https://doi.org/10.1039/c3ra43699c.
27. Lin H, Chen X, Li H, Yang M, Qi Y. Hydrothermal synthesis and characterizationof MoS2 nanorods. Mater Lett. 2010;64:1748–50. https://doi.org/10.1016/j.
matlet.2010.04.032.
28. Solomon G, Mazzaro R, Morandi V, Concina I, Vomiero A. Microwave-assisted
vs. Conventional Hydrothermal synthesis of MoS2 nanosheets: application
towards hydrogen evolution reaction. Cryst (Basel). 2020;10:1040. https://doi.
org/10.3390/cryst10111040.
29. Sheng X, Qian H, Lu J, Lu H, Hu K, Xu Z, Yu T, Xie J. Stepwise construction of
CdMoO4@CdS/MoS2 nanocomposites for effectively visible-induced photodegradation of rhodamine B and tetracycline. Mater Lett. 2021;303:130565.
https://doi.org/10.1016/j.matlet.2021.130565.
30. Liu C, Ma J, Zhang FJ, Wang YR, Kong C. Facile formation of Mo-vacancy
defective MoS2/CdS nanoparticles enhanced efficient hydrogen production. Colloids Surf Physicochem Eng Asp. 2022;643. https://doi.org/10.1016/j.
colsurfa.2022.128743.
31. Yin M, Zhang W, Qiao F, Sun J, Fan Y, Li Z. Hydrothermal synthesis of MoS2NiS/CdS with enhanced photocatalytic hydrogen production activity andstability. J Solid State Chem. 2019;270:531–8. https://doi.org/10.1016/j.
jssc.2018.12.022.
32. Li H, Liu L, Wang Z, Zheng X, Meng S, Chen S, Fu X. Optimizing the precursorof sulfur source for hydrothermal synthesis of high performance CdS forphotocatalytic hydrogen production. RSC Adv. 2018;8:11489–97. https://doi.
org/10.1039/C8RA00250A.
33. Jin X, Li G. Synthesis of MoS2/CdS nanospheres enhanced photocatalytic hydrogen evolution under visible light. J Mater Sci: Mater Electron.
2020;31:9377–84. https://doi.org/10.1007/s10854-020-03477-6.
34. Yin X-L, Li L-L, Li D-C, Li Z-J, Wang Y-X, Kong X-J, Zhao J-S, Jiang J-H, Qian
J-C, Pang D-H, Du X-X, Dou J-M. Noble-metal-free CdS@MoS2 core-shell
nanoheterostructures for efficient and stabilized visible-light-driven H2 generation. Int J Hydrogen Energy. 2019;44:16657–66. https://doi.org/10.1016/j.
ijhydene.2019.03.247.
35. Li L-L, Yin X-L, Pang D-H, Du X-X, Xue H, Zhou H-W, Yao Q-X, Wang H-W, Qian
J-C, Yang J, Li D-C, Dou J-M. One-pot synthesis of MoS2/CdS nanosphere
heterostructures for efficient H2 evolution under visible light irradiation. Int J Hydrogen Energy. 2019;44:31930–9. https://doi.org/10.1016/j.
ijhydene.2019.10.056.
36. Ben Ali M, Jo W-K, Elhouichet H, Boukherroub R. Reduced graphene oxide as
an efficient support for CdS-MoS2 heterostructures for enhanced photocatalytic H2 evolution. Int J Hydrogen Energy. 2017;42:16449–58. https://doi.
org/10.1016/j.ijhydene.2017.05.225.
37. Nagaraju G, Tharamani C, Chandrappa G, Livage J. Hydrothermal synthesisof amorphous MoS2 nanofiber bundles via acidification of ammonium
heptamolybdate tetrahydrate. Nanoscale Res Lett. 2007;2:461. https://doi.
org/10.1007/s11671-007-9087-z.
38. Lalithambika KC, Shanmugapriya K, Sriram S. Photocatalytic activity of MoS2
nanoparticles: an experimental and DFT analysis. Appl Phys Mater Sci Process.
2019;125. https://doi.org/10.1007/s00339-019-3120-9.
39. Kong X, Shen X, Zhang C, Oliaee SN, Peng Z. Engineering active sites of
two-dimensional MoS2 nanosheets for improving hydrogen evolution. Inorg
Chem Front. 2016;3:1376–80. https://doi.org/10.1039/C6QI00334F.
40. Kadam SR, Gosavi SW, Kale BB, Suzuki N, Terashima C, Fujishima A. Unique
CdS@MoS2 core shell heterostructure for efficient hydrogen generation
under natural sunlight. Sci Rep. 2019;9:12036. https://doi.org/10.1038/
s41598-019-48532-3.
41. Sahoo D, Kumar B, Sinha J, Ghosh S, Roy SS, Kaviraj B. Cost effective liquid
phase exfoliation of MoS2 nanosheets and photocatalytic activity for wastewater treatment enforced by visible light. Sci Rep. 2020;10:10759. https://doi.
org/10.1038/s41598-020-67683-2.
42. Lin L, Huang S, Zhu Y, Du B, Zhang Z, Chen C, Wang X, Zhang N. Constructionof CdS/MoS 2 heterojunction from core–shell MoS2 @Cd-MOF for efficientRahman et al. BMC Chemistry

43.

44.
45.

46.

47.

(2024) 18:135

photocatalytic hydrogen evolution. Dalton Trans. 2019;48:2715–21. https://doi.org/10.1039/C8DT04745F.
Zhao H, Fu H, Yang X, Xiong S, Han D, An X. MoS2/CdS rod-like nanocomposites as high-performance visible light photocatalyst for water splitting photocatalytic hydrogen production. Int J Hydrogen Energy. 2022;47:8247–60.
https://doi.org/10.1016/j.ijhydene.2021.12.171.
He G, Zhang Y, He Q. MoS2/CdS heterostructure for enhanced photoelectrochemical performance under visible light. Catalysts. 2019;9:379. https://doi.
org/10.3390/catal9040379.
Xiong M, Yan J, Chai B, Fan G, Song G. Liquid exfoliating CdS and MoS2 toconstruct 2D/2D MoS2/CdS heterojunctions with significantly boosted photocatalytic H2 evolution activity. J Mater Sci Technol. 2020;56:179–88. https://doi.org/10.1016/j.jmst.2020.03.037.
Liu S, Yang Y, Xiao W, Xia S, Jin C, Wang W, Li S, Zhong M, Wang S, Chen C.
Metal-organic frameworks derived porous MoS2/CdS heterostructure for
efficient photocatalytic performance towards hydrogen evolution andorganic pollutants. Int J Hydrogen Energy. 2023. https://doi.org/10.1016/j.
ijhydene.2023.05.050.
Zhang J, Tian B, Wang L, Xing M, Lei J, Photocatalysis. Springer Singapore,
Singapore, 2018. https://doi.org/10.1007/978-981-13-2113-9.

Page 15 of 15

48. Saeed M, Muneer M, ul Haq A, Akram N. Photocatalysis: an effective tool forphotodegradation of dyes—a review. Environ Sci Pollut Res. 2022;29:293–
311. https://doi.org/10.1007/s11356-021-16389-7.
49. Feng H, Zhou W, Zhang X, Zhang S, Liu B, Zhen D. Synthesis of Z-scheme MnCdS/MoS 2/TiO2 ternary photocatalysts for high-efficiency sunlight-driven
photocatalysis. Adv Compos Lett. 2019;28:2633366X1989502. https://doi.org/
10.1177/2633366X19895020.
50. Wang Z, Li J, Fu S, Guo D, Tang J, Yang X, Xu R, Sui G, Chen S. Constructionof MoS2/CdS/Bi2MoO6 Z-scheme photocatalyst for efficient photocatalytic
degradation under visible-light. J Solid State Chem. 2023;322:123957. https://doi.org/10.1016/j.jssc.2023.123957.

Publisher’s NoteSpringer Nature remains neutral with regard to jurisdictional claims inpublished maps and institutional affiliations.