Photocatalytic hydrogen evolution over Pt/Cd0.5Zn0.5S from saltwater using glucose as electron donor: An investigation of the influence of electrolyte NaCl

Surface property of Cd_0.5Zn_0.5S in basic aqueous solution was characterized by X-ray photoelectron spectroscope (XPS). The surface S species at Cd_0.5Zn_0.5S under basic condition is substituted by O species. The surface adsorption performance of glucose and NaCl was characterized by adsorption experiment and electrophoretic analysis. Glucose is adsorbed on Cd_0.5Zn_0.5S via two modes. Na⁺ can be also adsorbed on Cd_0.5Zn_0.5S. The effect of electrolyte NaCl on photocatalytic hydrogen evolution over Pt/Cd_0.5Zn_0.5S using glucose as an electron donor has been investigated under visible light irradiation. NaCl can promote markedly the photocatalytic hydrogen evolution, which is very important to practical application. The photocatalytic activity for hydrogen evolution from 3.0 mol L⁻¹ NaCl saltwater increases by 77% compared to that from pure water. A possible mechanism was discussed.     

In-situ photo-reducing graphene oxide to create Zn0.5Cd0.5S porous nanosheets/RGO composites as highly stable and efficient photoelectrocatalysts for visible-light-driven water splitting

Nanoporous Zn_0.5Cd_0.5S nanosheets/reduced graphene oxide (Zn_0.5Cd_0.5S/RGO) composites were prepared by a facile in-situ photoreduction method of graphene oxide (GO) in the presence of nanoporous Zn_0.5Cd_0.5S single-crystal-like nanosheets under visible light irradiation. The Zn_0.5Cd_0.5S/RGO photoelectrodes was characterized by TEM, IR and Raman spectra. Electrochemical measurements demonstrated that Zn_0.5Cd_0.5S/RGO photoelectrodes own a higher anodic photocurrent density, a lower zero current potential, and a higher photoelectrochemical response than that of pure Zn_0.5Cd_0.5S photoelectrodes under visible light irradiation under the same conditions. This high photochemical activity is predominately ascribed to the presence of RGO, which serves as the electron collector to efficiently prolong the lifetime of photoinduced electrons from the excited Zn_0.5Cd_0.5S nanosheets. In addition, the content of RGO in the composites had a remarkable influence on the photoelectrochemical behaviors of the photoelectrodes and the optimal RGO content was found to be 5 wt%. Zn_0.5Cd_0.5S/RGO composites at RGO content of 5 wt% reached a stable hydrogen production rate of 12.05 μmol h⁻¹ cm⁻² at an externally applied bias of 0.6 V. Furthermore, the Zn_0.5Cd_0.5S/RGO composites as photoelectrodes were found to be highly stable for hydrogen evolution reaction. The electrons stored in RGO are readily discharged or scavenged on demand by the applied positive bias to the counter electrode, and thus rectify the flow of electrons. Importantly, this work may open up a facile in-situ method for using RGO scaffold to create a stable photoelectrode with enhanced photoelectrochemical activities.     

CoPtx‐loaded Zn0.5Cd0.5S nanocomposites for enhanced visible light photocatalytic H2 production

Zn_0.5Cd_0.5S solid solution, modified with bimetallic CoPt_x nanoparticles, has been prepared using a two‐step organic solution method. The photocatalytic H₂ production rate of CoPt_x–Zn_0.5Cd_0.5S nanocomposites with different composition and percentage of CoPt_x was investigated. The results showed that the 1 wt% CoPt₃–Zn_0.5Cd_0.5S sample had the best activity which was 4.7 times higher than that of pure Zn_0.5Cd_0.5S and 1.2 times higher than that of Pt–Zn_0.5Cd_0.5S for photocatalytic H₂ production. The transient photocurrent response of the Zn_0.5Cd_0.5S showed an obvious increase in the current density after CoPt_x loading. Electrochemical impedance spectra measurements showed that the CoPt_x–Zn_0.5Cd_0.5S nanocomposites with x = 2 and 3 had lower charge transfer resistance R_t than that of Pt–Zn_0.5Cd_0.5S. The enhanced catalytic properties of the CoPt_x–Zn_0.5Cd_0.5S nanocomposites are attributed to their better accumulation ability for photoexcited electrons and higher rate for charge separation and transportation. Copyright © 2016 John Wiley & Sons, Ltd.     

NiSe2/Cd0.5Zn0.5S as a type-II heterojunction photocatalyst for enhanced photocatalytic hydrogen evolution

A designed type-II heterojunction photocatalyst, NiSe₂/Cd_0.5Zn_0.5S (NiSe₂/CZS), was successfully synthesized and it exhibits outstanding photocatalytic hydrogen evolution performance. The optimal loading amount of NiSe₂ on Cd_0.5Zn_0.5S is 13 wt %, and the corresponding hydrogen production rate is approximately 121.01 mmol g^?1 h^?1 under visible light. The heterojunction structure between Cd_0.5Zn_0.5S and NiSe₂ promoted the separation of photogenerated electron-hole pairs, effectively suppressed the photogenerated carrier recombination and endowed the material with excellent interfacial charge transfer properties, thus improving the photocatalytic performance.     

Modification of twin crystal Cd0.5Zn0.5S photocatalyst with up-conversion nanoparticles for efficient photocatalytic H2-production

The photocatalytic H₂-production by solar light has been considered a promising technology to converse solar energy into carbon-free hydrogen. The development of efficient and stable catalysts is the most urgent problem in this technology. Up to now, twin crystal Cd_0.5Zn_0.5S solid solution has been regarded as the best efficient pristine sulphide catalysts for visible-light-driven hydrogen production. Its catalytic activity can be remarkably improved further by loading suitable co-catalyst, such as PdP_~0.33S_~1.67, noble metal Pt, and NiS_x. However, these twin crystal Cd_0.5Zn_0.5S-based nanocomposites can only response to partial (wavelength less than 520 nm) visible light irradiation. Large amount of visible light and near infrared light (NIR) in solar spectrum can not be absorbed by Cd_0.5Zn_0.5S and, therefore, do not contribute to the H₂ production. In this work, β-NaYF₄:Yb³⁺,Tm³⁺,Er³⁺ up-conversion nanoparticles (UPNs) are prepared by a hydrothermal process and the corresponding nanocomposite photocatalyst (twin crystal Cd_0.5Zn_0.5S/β-NaYF₄:Yb³⁺,Tm³⁺,Er³⁺ (T-CZS/UPNs)) based on this kind of up-conversion nanoparticles and twin crystal Cd_0.5Zn_0.5S nanocrystal is successfully prepared for the first time. The compositions, morphologies, and optical properties of the T-CZS/UPNs are investigated using XRD, SEM, HRTEM, UV–vis–NIR absorption spectra and photoluminescence (PL) spectrum. The photocatalytic hydrogen evolution experiments are performed under the irradiation of visible light, NIR light or simulated solar light, respectively. The H₂ production rate over T-CZS/UPNs-15 nanocomposite under the irradiation of simulated solar light in the presence of Na₂S/Na₂SO₃ as sacrificial agent is measured to be 159.3 mmol/h/g, which is 3.4 times higher than that of pristine T-CZS nanocrystals. In particular, this nanocomposite exhibits also significant photocatalytic hydrogen production rate (0.497 mmol/g/h) under NIR light irradiation (λ > 800 nm), reveals the contribution of NIR light to H₂ production via an photon-up-conversion process. This work gives an innovative vision in constructing efficient photocatalysts to make the efficient use of NIR solar light.     

Synthesis of novel CoxMo1-xS-Cd0.5Zn0.5S composites with significantly improved photocatalytic hydrogen evolution performance under visible-light illumination

Recently, MoS₂ incorporates with Co²⁺ (or Ni²⁺) was found to increase the photocatalytic performance of semiconducting materials more effectively. In this study, novel Co_xMo_1-xS was effectively deposited on the surface of Zn_0.5Cd_0.5S semiconductors as an efficient promotor using in-situ hydrothermal process. The as-prepared Co_xMo_1-xS-Zn_0.5Cd_0.5S composites are examined by the following techniques: XRD, TEM, DRS, XPS, PL and TRPL. The photocatalytic hydrogen evolution performance under visible illumination over Zn_0.5Cd_0.5S is remarkably increased by adding cheap Co_xMo_1-xS as promotor. The Co_xMo_1-xS-Zn_0.5Cd_0.5S hybrid specimen with 10% molar amount illustrates the best catalytic performance with a homologous hydrogen generation rate of 188.65 μmol h⁻¹, which is estimated to be 14.5 folds than that of unmodified Zn_0.5Cd_0.5S specimen in the presence of visible light. The apparent quantum yield of Co_0.3Mo_0.7Zn_0.5Cd_0.5S sample is determined to be 16.72% at monochromatic light of 420 nm. The experimental outcomes indicate that the synergistic action between Co_xMo_1-xS and Zn_0.5Cd_0.5S obviously promotes transfer of photo-induced charge carriers in the hybrid sample. A reasonable catalytic mechanism for the increased photocatalytic performance of Co_xMo_1-xS promotor was presented and authenticated by TRPL measure, which would present a new notion for the design of ideal semiconductors with plummy photocatalytic capability.     

Cd0.5Zn0.5S/Ni2P noble-metal-free photocatalyst for high-efficient photocatalytic hydrogen production: Ni2P boosting separation of photocarriers

Establishing efficient co-catalytic loaded semiconductors for efficient charge separation is a hopeful way for enhance photocatalytic water splitting hydrogen evolution. Herein, we successfully constructed the Cd_0.5Zn_0.5S/Ni₂P (CZS/Ni₂P) nanocomposites via two-step hydrothermal method. The CZS/Ni₂P composites show much improved activity than the origin CZS for photocatalytic H₂ generation. When the content of Ni₂P loaded on the Cd_0.5Zn_0.5S (CZS) is 0.3 mol%, the photocatalyst achieves the highest photocatalytic hydrogen generation rate of 41.26 mmol g⁻¹ h⁻¹ under visible light. The Ni–S bonds on the close contact interface between CZS and Ni₂P can be act as electron-bridge to provide a channel for electron transfer. During the photocatalysis processing, Ni₂P can be used as electron traps to attract electrons from CZS, resulting in the improvement of the photocatalytic performance.     

In-situ construction of Mo3S4/Cd0.5Zn0.5S heterojunction: An efficient and stable photocatalyst for H2 evolution

In this work, Mo₃S₄/Cd_0.5Zn_0.5S heterojunction with abundant porosity was in-situ synthesized by one-step hydrothermal method. Characterization results clearly indicate that the composite material are composed of nanoparticles with an average particle diameter about 65 nm and abundant inter-particle pores are present in between. The XPS analysis found that when Mo₃S₄ was introduced, the XPS peak positions of Cd²⁺ and Zn²⁺ were shifted from the XPS peak positions of Cd²⁺ and Zn²⁺ in pristine Cd_0.5Zn_0.5S, which indicates that there is an interaction between Mo₃S₄ and Cd_0.5Zn_0.5S at the interface. Subsequently, the Mo₃S₄/Cd_0.5Zn_0.5S (72.1 mmol h⁻¹ g⁻¹) heterojunction can achieve much higher photocatalytic hydrogen production rate than the pristine Cd_0.5Zn_0.5S (7.54 mmol h⁻¹ g⁻¹), and even higher than Cd_0.5Zn_0.5S (56.44 mmol h⁻¹ g⁻¹) loaded with the noble metal Pt (2.0%), indicating that heterojunction can effectively enhance photocatalytic activity. In addition, the improvement in photocatalytic activity of Mo₃S₄/Cd_0.5Zn_0.5S is highly related with enhanced absorption and utilization of light due to the presence of the inter-particle pores which inhibit recombination of electron-hole pairs, promote charge separation and accelerate the migration of photogenerated carriers.     

Construction of 1D/0D/2D Zn0.5Cd0.5S/PdAg/g-C3N4 ternary heterojunction composites for efficient photocatalytic hydrogen evolution

A high-efficiency and easy-available approach was developed to obtain a ternary heterojunction composites with advanced hydrogen evolution reaction (HER) performance under visible light by water split. PdAg bimetallic nanoparticles make a close contact interface between g-C₃N₄(CN) and Zn_0.5Cd_0.5S(ZCS). Under visible light irradiation, CN and ZCS are both excited to generate electron-hole pairs, PdAg bimetallic nanoparticles act as a bridge between CN and ZCS. Not only can the photogenerated electrons from CN be captured, but they can also be quickly transferred to the surface of ZCS and participate in the photocatalytic reaction to release H₂, and the recombination of charge carriers between the contact interface of ZCS and CN can be significantly inhibited. In addition, the thin CN layer reduces the photocorrosion of the ZCS and enhances the specific surface area of the composite material. After testing, the composite material with 30 wt% ZCS and 4 wt% PdAg demonstrates hydrogen evolution performance, up to 6250.7 μmol g^?1h^?1, which is 753 times the hydrogen evolution rate of single-component CN and 12.6 times of ZCS/CN. Compared with single-component and two-component photocatalysts, the ternary ZCS/PdAg/CN photocatalyst achieves significantly enhanced photocatalytic activity.     

Crown-like Zn0.5Cd0.5S/M-TiO2 composites derived from metal-organic frameworks for photocatalytic hydrogen production

Photocatalytic hydrogen production has been recognized as one of the most desirable approaches to overcome the worldwide energy and environmental issues. Here, novel sea urchin-like Zn_0.5Cd_0.5S and mesoporous TiO₂ (M-TiO₂) are designed, and a series of crown-like Zn_0.5Cd_0.5S/M-TiO₂ composites with different contents of M-TiO₂ are synthesized by hydrothermal method. The optimum hydrogen production rate of composites reaches 180.4 mmolh^?1g^?1 with the AQE up to 48.9% at 420 nm, which is 3.5 and 216 times that of pure Zn_0.5Cd_0.5S and the M-TiO₂, respectively. The outstanding performance of optimized Zn_0.5Cd_0.5S/M-TiO₂ composite prepared in this work exceeds most reported Cd-S-based catalysts. The improvement on the photocatalytic performance of composites is mainly due to the enlarged specific surface area, the exposure of more active sites, and the enhancement of the electron-hole separation efficiency.     

Fabrication of direct Z-scheme heterojunction between Zn0.5Cd0.5S and N-rich graphite carbon nitride for boosted H2 production

In this work, a novel direct Z-scheme g-C₃N₅/Zn_0.5Cd_0.5S (CN/ZCS) heterojunction was successfully synthesized. Furthermore, its photocatalytic activity for hydrogen production was also investigated, whose photoluminescence spectrum revealed the charge transfer procedure of g-C₃N₅ and ZCS. Moreover, the optimized hydrogen production rate of ZCS with 15 wt% of g-C₃N₅ (15% CN/ZCS) was about 142.8 mmol/h/g and quantum efficiency (Q.E.) was circa 33.7% under 420 nm monochromatic light. Compared with the pure ZCS and ZCS with 2 wt% of Pt, the 15% CN/ZCS composite exhibited considerable improved hydrogen production rate, which was about 20 times and 7 times, respectively. The formation of CN/ZCS composite resulted in faster separation of the photogenerated electron-hole pairs. Our work may supply valuable data for the application of g-C₃N₅ on photocatalysis.     

Design and fabrication of C–Mn0.5Cd0.5S/Cu3P ternary heterojunction catalyst for photocatalytic hydrogen evolution

Photocatalytic hydrogen evolution from water splitting is a promising strategy to solve the energy demand of human beings. Here, we first designed a C–Mn_0.5Cd_0.5S/Cu₃P ternary heterojunction catalyst for photocatalytic hydrogen production. The results show that the combination of C and Cu₃P can effectively improve the photocatalytic activity of Mn_0.5Cd_0.5S. C–Mn_0.5Cd_0.5S loading with 5 wt% Cu₃P exhibits the highest hydrogen evolution rate (44.1 mmol g⁻¹ h⁻¹), which is 3.2 and 2.8 times higher than that of pure Mn_0.5Cd_0.5S (13.7 mmol g⁻¹ h⁻¹) and Mn_0.5Cd_0.5S/3 wt%Pt (15.6 mmol g⁻¹ h⁻¹), respectively. In addition, it shows a high hydrogen evolution rate (19.6 mmol g⁻¹ h⁻¹) under visible light (≥420 nm) irritation and the apparent quantum efficiency (AQE) is detected to be 3.2% at 420 nm. The enhanced photocatalytic activity can be attributed to the good conductivity of C and the formation of p-n heterojunction, which is beneficial for light harvesting and the separation and transportation of charge carriers. Besides, a possible mechanism is proposed. This work provides an effective way to improve the photocatalytic activity of Mn_0.5Cd_0.5S by using non noble metal co-catalysts.     

Preparation of multiwalled carbon nanotubes/Cd0.8Zn0.2S nanocomposite and its photocatalytic hydrogen production under visible-light

Multiwalled carbon nanotubes (MWCNTs)/Cd_0.8Zn_0.2S nanocomposites were synthesized via the simple co-precipitation of pretreated MWCNTs, acetates and sodium sulfide. The photocatalytic activities for hydrogen production of the produced MWCNTs/Cd_0.8Zn_0.2S with different amount of MWCNTs were systematically investigated under visible-light (λ ≥ 420 nm) irradiation. Enhanced photoactivity of the nanocomposite was observed and can be attributed to the synergetic effect of its components’ intrinsic properties, such as excellent light absorption and charge separation on the interfaces between the modified MWCNTs and Cd_0.8Zn_0.2S. It is also found that the nanocomposite with 15 wt% MWCNTs shows a higher photocatalytic hydrogen production efficiency and photostability than the pristine CdS and Cd_0.8Zn_0.2S nanoparticles. The MWCNTs/Cd_0.8Zn_0.2S nanocomposite holds promise for hydrogen production by improving the visible-light-driven photoactivity and photostability of Cd_0.8Zn_0.2S.     

Noble metal-free bimetallic NiCo decorated Zn0.5Cd0.5S solid solution for enhanced photocatalytic H2 evolution under visible light

As we know, noble metal (Pt, Pd and Au) with appropriate adsorption free energy of H atoms and higher work function as cocatalyst has been considered to be an effective tactic to enhance photocatalytic activity. However, they are limited severely by scarcity and high-cost. Herein, Zn_0.5Cd_0.5S solid-solution photocatalyst decorated with noble metal-free NiCo cocatalyst has been successfully obtained through one-step photochemical route. It is found that the lifespan of charge carriers of Zn_0.5Cd_0.5S@NiCo can be prolonged dramatically after modification, and the photocatalytic H₂ rate reach to 34.7  mmol g⁻¹·h⁻¹ is nearly 9 times higher than the bare Zn_0.5Cd_0.5S (λ ≥ 420 nm). The superior photocatalytic activity for ZCS@NiCo could be mainly ascribed to higher separation and transfer efficiency of photogenerated carriers by introduced bimetallic NiCo cocatalysts possessing the superior electron transfer property and reducing the onset over-potential of water reduction, which was proved by experiment. This study can provide a potential strategy to design a more efficient noble metal-free cocatalyst over photocatalyst.     

Wavelength-dependent photoactivity of ZnxCd1−xS and ZnCo2O4/ZnxCd1−xS for H2 and H2O2 production

Zinc cadmium sulfide (Zn_xCd_1?xS) is a good photocatalyst for hydrogen evolution reaction (HER), but an optimum x (x_m) at which a maximum HER rate is reached varies from one report to another. In this work, we examine the effect of light wavelength, not only for the HER to H₂ in the presence of Na₂S and Na₂SO₃, but also for oxygen reduction reaction (ORR) without addition of any sacrifices. For the HER under a 365 and 420 nm LED lamp, the x_m were 0.9 and 0.7, respectively. For the HER under a 330 and 395–515 nm cut-off xenon lamp, the x_m were 0.7 and 0.5, respectively. For the ORR under a 420 nm cut-off halogen lamp, a maximum production of H₂O₂ was observed at x = 0.3. Furthermore, after 4% ZnCo₂O₄ loading, Zn_xCd_1?xS had an increased activity and stability, either for the HER or for the ORR. Through a (photo)electrochemical measurement, it is proposed that the photocatalytic activity of Zn_xCd_1?xS is determined by its light absorptivity and electron reactivity. The improved performance of n-type Zn_xCd_1?xS by p-type ZnCo₂O₄ is due to formation of a p-n junction, promoting the HER (ORR) on Zn_xCd_1?xS, and the sulfide (water) oxidation on ZnCo₂O₄. This work highlights that Zn_xCd_1-xS is a promising photocatalyst for H₂ and H₂O₂ production, respectively.     

Remarkable enhancement of photocatalytic hydrogen evolution over Cd0.5Zn0.5S by bismuth-doping

Bi³⁺ doped Cd_0.5Zn_0.5S photocatalysts were prepared by a simple hydrothermal method, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS), energy dispersive X-ray spectroscopy (EDX), BET and UV-Vis absorption spectroscope techniques. When Bi³⁺ doping content is lower, the doping ions lie at the surface lattice sites, whereas when the doping content is higher, the ions also enter the bulk lattice sites. Their photoactivities were evaluated by hydrogen evolution from aqueous solution containing Na₂S and Na₂SO₃ as a hole scavenger under visible light (λ ≥ 420 nm) irradiation. Bi³⁺ doping enhances markedly photocatalytic activity. When Bi³⁺ doping content is 0.10 mole %, the photocatalyst exhibits the highest activity, and the average apparent quantum yield amounts to 9.71% during 30 h irradiation. The possible mechanism was discussed.     

Ni(OH)2 modified Mn0.5Cd0.5S with efficient photocatalytic H2 evolution activity under visible-light

Developing high-efficiency photocatalysts for water decomposition is one of the major challenges in converting solar energy to chemical energy. In this paper, Ni(OH)₂ modified Mn_0.5Cd_0.5S solid solution without the use of precious metals is successfully synthesized via hydrothermal method followed by precipitation, the photocatalytic activity for hydrogen evolution and stability of composite samples present significant improvement with respect to the pristine Mn_0.5Cd_0.5S. These improvements are attributed to that Mn_0.5Cd_0.5S CB potential (−0.7 V vs. NHE) is more negative than the potential of Ni²⁺/Ni (−0.23 V vs. NHE), which promotes the transfer of photo-generated electrons from Mn_0.5Cd_0.5S CB to Ni(OH)₂ for H₂ production as well as partial reduction of Ni²⁺ to Ni⁰, leaving VB holes to oxidize the sacrificial reagents. The metal Ni atoms with conductivity and Ni(OH)₂ nanoparticles not only boost the segregation and transfer of photo-induced carriers but also act as water-reduction promoter, thereby promoting the photocatalytic activity for hydrogen release. A novel visible light responsive Mn_xCd_1-xS-based photocatalytic material promising for practical applications is provided in this subject.     

Highly efficient visible-light-assisted photocatalytic hydrogen generation from water splitting catalyzed by Zn0.5Cd0.5S/Ni2P heterostructures

Development of heterostructured photocatalysts which can facilitate spatial separation of photo-generated charge carriers is crucial for achieving improved photocatalytic H₂ production. Consequently, herein, we report the synthesis of Zn_0.5Cd_0.5S/Ni₂P heterojunction photocatalysts with varying amount of Ni₂P, 0.5 (S1), 1 (S2), 3 (S3), 5 (S4) and 10wt% (S5) for the efficient visible-light-assisted H₂ generation by water splitting. The heterostructures were characterized thoroughly by PXRD, FE-SEM, EDS, HR-TEM and XPS studies. FE-SEM and HR-TEM analyses of the samples unveiled the presence of Zn_0.5Cd_0.5S microspheres composed of smaller nanocrystals with the surface of the microspheres covered with Ni₂P nanosheets and the intimate contact between the Zn_0.5Cd_0.5S and the Ni₂P. Further, visible-light-assisted photocatalytic investigation of the samples showed excellent water splitting activity of the heterostructure, Zn_0.5Cd_0.5S/1wt%Ni₂P (S2) with very high H₂ generation rate of 21.19 mmol h^?1g^?1 and the AQY of 21.16% at 450 nm with turnover number (TON) and turnover frequency (TOF) of 251,516 and 62,879 h^?1 respectively. Interestingly, H₂ generation activity of S2 was found to be about four times higher than that of pure Zn_0.5Cd_0.5S (5.0 mmol h^?1g^?1) and about 240 times higher than that of CdS/1wt%Ni₂P. The enhanced H₂ generation activity of S2 has been attributed to efficient spatial separation of photogenerated charge carriers and the presence of highly reactive Ni₂P sites on the surface of Zn_0.5Cd_0.5S microspheres. A possible mechanism for the enhanced photocatalytic H₂ generation activity of Zn_0.5Cd_0.5S/1wt%Ni₂P (S2) has been proposed and is further supported by photoluminescence and photocurrent measurements. Furthermore, the catalyst, S2 can be recycled for several cycles without significant loss of catalytic activity and photostability. Remarkably, the H₂ generation activity of S2 was found to be even higher than the reported examples of Zn_xCd_1-xS doped with noble metal cocatalysts. Hence, the present study highlights the importance of Zn_0.5Cd_0.5S/Ni₂P heterostructures based on non-noble metal co-catalyst for efficient visible-light-driven H₂ production from water splitting.     

Carbon nanotube modified Zn0.83Cd0.17S nanocomposite photocatalyst and its hydrogen production under visible-light

Visible light photocatalytic H₂ production from water splitting has received much attention for its potential application in converting solar energy into chemical energy. In this paper, carbon nanotube modified Zn_0.83Cd_0.17S nanocomposite was prepared by a solvothermal method. CNTS can efficiently suppress the growth of chalcogenide nanoparticles and improve the dispersity of the nanocomposite. The absorption edges of Zn_0.83Cd_0.17S/CNTs nanocomposites red-shift and the response of the visible-light region (500–800 nm) is strengthened with the increase of CNTs contents in the samples. The prepared Zn_0.83Cd_0.17S/CNTs nanocomposites exhibit an enhanced photocatalytic H₂-production activity and an optimum amount of CNT is determined to be ca. 0.25 wt%, at which the Zn_0.83Cd_0.17S/CNTs displays the highest photocatalytic activity under the irradiation of Xe lamp, with an H₂ production rate of 5.41 mmol h⁻¹ g⁻¹. Furthermore, the prepared Zn_0.83Cd_0.17S/CNTs nanocomposite is photostable and no photocorrosion was observed after photocatalytic recycling, compared with pure Zn_0.83Cd_0.17S photocatalyst.     

An efficient ternary Mn0.2Cd0.8S/MoS2/Co3O4 heterojunction for visible-light-driven photocatalytic H2 evolution

An efficient ternary Mn_0.2Cd_0.8S/MoS₂/Co₃O₄ heterojunction was prepared and displayed excellent photocatalytic performance. The ternary Mn_0.2Cd_0.8S/MoS₂/Co₃O₄ heterojunction with 0.62 wt% of MoS₂ and 1.51 wt% of Co₃O₄ achieved the highest H₂ evolution activity (16.45 mmol g⁻¹ h⁻¹), which was well above Mn_0.2Cd_0.8S (2.72 mmol g⁻¹ h⁻¹). The improved H₂ evolution activity was ascribed to the synergistic effect of the Mn_0.2Cd_0.8S/Co₃O₄ p–n heterojunction and the modification of MoS₂ as a co-catalyst. This work can offer a new perspective for the application of Mn_xCd_1−xS-based ternary heterojunction towards solar energy conversion.