Vanadium diboride as an efficient cocatalyst coupled with CdS for enhanced visible light photocatalytic H2 evolution

Exploiting active, stable, and cost-efficient cocatalysts is crucial to enhance the photocatalytic performance of semiconductor-based photocatalysts for H₂ evolution from water splitting. Herein, we report on using vanadium diboride (VB₂) as an efficient cocatalyst to enhance the photocatalytic H₂ evolution performance of CdS nanoparticles under visible light irradiation (λ ≥ 420 nm). The CdS/VB₂ composites prepared by a facile solution-mixing method exhibit much improved H₂ evolution activities in 10 vol% lactic acid (LA) solution relative to pristine CdS. The most efficient CdS/VB₂ composite with 20 wt% VB₂ (CB20) exhibits a H₂ evolution rate as high as 12.1 mmol h⁻¹ g⁻¹, which is about 11 times higher than that of CdS alone (1.1 mmol h⁻¹ g⁻¹). Moreover, the highest apparent quantum efficiency (AQE) of 4.4% is recorded on CB20 at 420 nm. The improved photocatalytic activity of CdS/VB₂ composite can be attributed to the excellent cocatalytic effect of VB₂, which can not only enhance the charge separation on CdS but also accelerate the H₂ evolution kinetics. This work demonstrates the great potential of using transition metal brodies (TMBs) as efficient cocatalysts for developing noble-metal-free and stable photocatalysts for solar photocatalytic H₂ evolution.     

Efficient photocatalytic hydrogen evolution with high-crystallinity and noble metal-free red phosphorus-CdS nanorods

The photocatalytic production of H₂ by low-cost semiconductors is a promising approach to store solar energy. Photocatalysts with heterojunctions convert visible light into H₂ faster because of more efficient charge separation. The morphology, the structure, and the crystallinity are additional factors to consider when developing a photocatalyst. Here, highly-crystalline CdS nanorod (NR) were synthesized by a facile one-pot process. Under visible light, pure CdS NR produced H₂ 2.1 times faster than conventional CdS nanoparticles (NP). CdS NR were then combined with the semiconductor red phosphorus (RPh). A CdS NR-based heterojunction photocatalyst with RPh_5% had an excellent photocatalytic H₂ evolution rate of 11.72 mmol g⁻¹ h⁻¹, which was 3.6 times higher than pure CdS NR. The apparent quantum efficiency of RPh_5%/CdS NR was 19.57%. Furthermore, RPh_5%/CdS NR exhibited a superior photogenerated charge separation efficiency and was stable with little photocorrosion compared to CdS NP showing the high potential of this heterojunction photocatalyst.     

Hydrogen generation by photocatalytic reforming of glucose with heterostructured CdS/MoS2 composites under visible light irradiation

A binary heterostructured CdS/MoS₂ flowerlike composite photocatalysts was synthesized via a simple one-pot hydrothermal method. This photocatalyst demonstrated higher photocatalytic hydrogen production activity than pure MoS₂. The heterojunction formed between MoS₂ and CdS seems to promote interfacial charge transfer (IFCT), suppress the recombination of photogenerated electron–hole pairs, and enhance the hydrogen generation. Based on the good match between the conduction band (CB) edge of CdS and that of MoS₂, electrons in the CB of CdS can be transferred to MoS₂ easily through the heterojunction between them, which prevents the accumulation of electrons in the CB of CdS, inhibiting photocorrosion itself and greatly enhancing stability of catalyst. Hydrogen evolution reaction (HER) using Na₂S/Na₂SO₃ or glucose as sacrificial agents in aqueous solution was investigated. The ratio between CdS and MoS₂ plays an important role in the photocatalytic hydrogen generation. When the ratio between CdS and MoS₂ reaches 40 wt%, the photocatalyst showed a superior H₂ evolution rate of 55.0 mmol g⁻¹ h⁻¹ with glucose as sacrificial agent under visible light, which is 1.2 times higher than using Na₂S/Na₂SO₃ as sacrificial agent. Our experimental results demonstrate that MoS₂-based binary heterostructured composites are promising for photocorrosion inhibition and highly efficient H₂ generation.     

Well-designed NiS/CdS nanoparticles heterojunction for efficient visible-light photocatalytic H2 evolution

Heterojunction photocatalysts based on semiconducting nanoparticles show excellent performance in many photocatalytic reactions. In this study, 0D/0D heterojunction photocatalysts containing CdS and NiS nanoparticles (NPs) were successfully synthesized by a chemical precipitation method. The NiS NPs were grown in situ on CdS NPs, ensuring intimate contact between the semiconductors and improving the separation efficiency of hole-electron pairs. The obtained NiS/CdS composite delivered a photocatalytic H₂ evolution rate (7.49 mmol h^?1 g^?1), which was 39.42 times as high as that of pure CdS (0.19 mmol h^?1 g^?1). This study demonstrates the advantages of 0D/0D heterojunction photocatalysts for visible light-driven photocatalytic hydrogen production.     

A novel pathway toward efficient improvement of the photocatalytic activity and stability of CdS-based photocatalyst for light driven H2 evolution: The synergistic effect between CdS and SrWO4

It has been a research hot spot how to efficiently heighten the photocatalytic activity and stability of CdS-based photocatalysts for H₂ evolution. Here, SrWO₄/CdS nanoparticles which contained CdS/SrWO₄ heterojunctions were prepared. Meanwhile, their photocatalytic performance and stability were investigated in detail for H₂ evolution. At last, the photocatalytic mechanism of the SrWO₄/CdS nanoparticles was discussed roughly. The results show that the photocatalytic performance of CdS can be heightened significantly due to introduction of SrWO₄. The fastest evolution rate of H₂ over the SrWO₄/CdS nanoparticles is 392.5 μmol g⁻¹ h⁻¹, which is 5.8 times as high as that over the pure CdS nanomaterial. More interestingly, the SrWO₄/CdS nanoparticles possess excellent stability. The evolution rate of H₂ over the photocatalyst used 10 times can be up to 473 μmol g⁻¹ h⁻¹, which is the same as that over the once used sample, even is 37% higher than that over of the fresh one. In contrast, after used five times, the photocatalytic activity of the pure CdS nanomaterial is only 57% of that of the fresh sample. This study will supply a new idea for the design and development of highly stable and efficient CdS-based photocatalysts for H₂ evolution in the future.     

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.     

Efficient interfacial charge transfer of 2D/2D CoP/CdS heterojunction for extremely boosted photocatalytic H2 evolution performance

Constructing 2D/2D heterojunction photocatalysts has attracted great attentions due to their inherent advantages such as larger interfacial contact areas, short transfer distance of charges and abundant reaction active sites. Herein, 2D/2D CoP/CdS heterojunctions were successfully fabricated and employed in photocatalytic H₂ evolution using lactic acid as sacrificial reagents. The multiple characteristic techniques were adopted to investigate the crystalline phases, morphologies, optical properties and textual structures of heterojunctions. It was found that integrating 2D CoP nanosheets as cocatalysts with 2D CdS nanosheets by Co–S chemical bonds would significantly boost the photocatalytic H₂ evolution performances, and the 7 wt% 2D/2D CoP/CdS heterojunction possessed the maximal H₂ evolution rate of 92.54 mmol g^?1 h^?1, approximately 31 times higher than that of bare 2D CdS nanosheets. Photoelectrochemical, steady photoluminescence (PL) and time-resolved photoluminescence (TRPL) measurements indicated that there existed an effective charge separation and migration over 2D/2D CoP/CdS heterojunction, which then markedly lengthened the photoinduced electrons average lifetimes, retarded the recombination of charge carriers, and caused the dramatically boosted photocatalytic H₂ evolution activity. Moreover, the density functional theory (DFT) calculation further corroborated that the efficient charge transfer occurred at the interfaces of CoP/CdS heterojunction. This present research puts forward a promising strategy to engineer the 2D/2D heterojunction photocatalysts endowed with an appealing photocatalytic H₂ evolution performance.     

In-situ constructing cobalt incorporated nitrogen-doped carbon/CdS heterojunction with efficient interfacial charge transfer for photocatalytic hydrogen evolution

Designing an efficient heterojunction interface is an effective way to promote the electrons' transfer and improve the photocatalytic H₂ evolution performance. In this work, a novel hollow hybrid system of Co@NC/CdS has been fabricated and constructed. CdS nanospheres are anchored on the hollow-structured cobalt incorporated nitrogen-doped carbon (Co@NC) through a one-pot in-situ chemical deposition approach, forming an intimate interface and establishing an excellent channel to improve the electrons transfer and charge carriers separation between CdS and Co@NC cocatalyst, which immensely promotes the photocatalytic activity. The rate of photocatalytic H₂ evolution over hollow structured Co@NC/CdS heterojunction can be achieved 8.2 mmol g^?1 h^?1, which is about 45 times of pristine CdS nanospheres. The photocatalytic H₂ evolution mechanism has been investigated by the techniques of photoluminescence (PL) spectra, photocurrent-time (i-t) curves, electrochemical impedance spectroscopy (EIS) etc. This work aims to provide a new way in developing of high-performance advanced 3D heterojunction for photocatalytic hydrogen evolution.     

Facile synthesis of CeO2/g-C3N4 nanocomposites with significantly improved visible-light photocatalytic activity for hydrogen evolution

Ceria dioxide supported on graphitic carbon nitride (CeO₂/g-C₃N₄) composites were facilely synthesized to be application for photocatalytic hydrogen (H₂) generation in this present work. The physical and chemical properties of CeO₂/g-C₃N₄ nanocomposites were determined via a series of characterizations. The CeO₂/g-C₃N₄ composites prepared by facile thermal annealing and rotation-evaporation method exhibit excellent photocatalytic H₂ evolution with visible-light illumination. The best hydrogen generation rate of CeO₂/g-C₃N₄ composite with 1.5 wt% Pt is 0.83 mmol h⁻¹ g⁻¹, which is almost same as that of composite with 3 wt% Pt prepared by simple physical mixing method. The significantly developed photocatalytic activity of CeO₂/g-C₃N₄ composite is majorly ascribed to the stronger interfacial effects with the more visible-light absorbance and faster electron transfer. This work reveals that construction of the CeO₂/g-C₃N₄ composite with high disperse and close knit by the facile thermal annealing and rotation-evaporation method could be an effective method to achieve excellent photocatalytic hydrogen evolution performance.     

In-situ synthesis of ternary heterojunctions via g-C3N4 coupling with noble-metal-free NiS and CdS with efficient visible-light-induced photocatalytic H2 evolution and mechanism insight

The two-dimensional (2D) graphitic carbon nitride (g-C₃N₄) nanosheets based composites are prepared in the form of the NiS/g-C₃N₄, CdS/g-C₃N₄ and CdS/NiS/g-C₃N₄ using a facile and reliable method of chemical deposition. The TEM and HRTEM images demonstrated a spectacular representation of the 2D lamellar microstructure of the g-C₃N₄ with adequately attached CdS and NiS nanoparticles. The changes in crystallinity and the surface elemental valence states of composites with the incorporation of two metal sulphides are studied, which confirmed the formation of composites. The photocatalytic response of the composites was estimated by photodegradation of Rhodamine B (C₂₈H₃₁ClN₂O₃–RhB), and the ternary composite CdS/NiS/g-C₃N₄ samples exhibited the superior photocatalytic performance. Further, the free radical capture and electron paramagnetic resonance (EPR) spectroscopy experiments identified the main active species that contributed to the photocatalytic reaction. Besides, the samples’ photocatalytic performance was evaluated by photocatalytic hydrogen production. The stability of the performance-optimized composite was determined by employing cyclic experiments over five cycles. The CdS/NiS/g-C₃N₄ showed the highest efficiency of hydrogen production i.e. about 423.37 μmol.g^?1.h^?1, which is 2.89 times that of the pristine g-C₃N₄. Finally, two types of heterojunction structures were proposed to interpret the enhanced photocatalytic efficiency.     

Noble-metal-free CdS@MoS2 core-shell nanoheterostructures for efficient and stabilized visible-light-driven H2 generation

Photocatalytic water splitting is considered to be a green H₂ generation approach and has potential to be applied in the future. As a photocatalytic active material for H₂ evolution, CdS is a good candidate. However, the pristine CdS still suffers from low efficiency and poor stability. To address those issues, we developed noble-metal-free CdS@MoS₂ core-shell nanoheterostructures which exhibit outstanding photocatalytic H₂ evolution performance thus far with rate of 62.55 mmol g⁻¹ h⁻¹, which exceeds that of pristine CdS by a factor of 148. Meanwhile, the photocatalytic stability can be well retained with no deterioration of activity in 24 h reaction. The excellent performance can be reasonably attributed to the low crystallinity of MoS₂ with numerous active sites provided, and the band alignment of CdS and MoS₂ as determined by valence band-XPS and Mott-Schottky plots analysis, which significantly promotes charge transportation and separation. The enhanced photocatalytic stability here should be ascribed to the intimate growth of MoS₂ shells which significantly passivate the surface trap states of CdS cores and thus the photocorrosion is remarkably retarded. This novel strategy will inspire the fabrication of other photocatalytic systems, and may high-efficient photocatalysts be obtained.     

Construction of porous Ni2P cocatalyst and its promotion effect on photocatalytic H2 production reaction and CO2 reduction

Due to superior light absorption abilities, porous materials are suitable to be served in photocatalytic reactions. In this study, porous Ni₂P is target-constructed from porous Ni(OH)₂ nanoflower. Promotion effect of the porous Ni₂P as cocatalyst is confirmed on photocatalytic performance of Ni₂P/CdS composite. The constructed porous Ni₂P/CdS photocatalyst shows much higher photocatalytic H₂ evolution rate (111.3 mmol h⁻¹ g⁻¹) from water and much higher CO (178.0 μmol h⁻¹ g⁻¹) and CH₄ (61.2 μmol h⁻¹ g⁻¹) evolution rates from CO₂ reduction than non-porous Ni₂P/CdS photocatalyst. Characterizations including UV-Vis diffuse reflectance, photoluminescence, transient photocurrent response, electrochemical impedance and electron paramagnetic resonance are conducted to verify the role of porous Ni₂P cocatalyst. The slow photon effect derived from porous structure Ni₂P is found to improve light path and increase the absorption utilization of light. The enhanced photocurrent intensity and the lowered resistance of porous Ni₂P/CdS due to the formed heterojunctions indicate much rapid isolation of photogenerated electron-hole pairs and rapid charge transfer of electrons. The higher signal of ⋅O₂- radicals is detected in porous Ni₂P/CdS than non-porous Ni₂P/CdS, which result in the remarkable photocatalyst activities of porous Ni₂P/CdS. Reaction mechanisms over Ni₂P/CdS photocatalyst are illustrated with a Z-scheme charge transfer path.     

In- situ solid-phase fabrication of Ag/AgX (X=Cl,Br, I)/g-C3N4 composites for enhanced visible-light hydrogen evolution

In this work, a series of Ag/AgX (X = Cl, Br, I)/g-C₃N₄ (Ag/AgX/CN) composites were successfully fabricated by an in-situ solid phase method. The morphology and structure, photoluminescence and photoelectrochemical properties of composites were investigated in detail. The as-prepared Ag/AgX/CN composites were used as H₂ evolution photocatalysts under visible-light irradiation with a sacrificial agent. The experimental results revealed that Ag/AgI/CN-4 composite possesses highest-H₂ evolution rate (up to 59.22 μmol g⁻¹ h⁻¹) which are approximately 31 times higher than that of pure g-C₃N₄ (1.94 μmol g⁻¹ h⁻¹). In addition, Ag/AgCl/CN-4 and Ag/AgBr/CN-4 composites also present high photocatalytic activities yielding, 26.39 and 18.05 μmol_H2 g⁻¹ h⁻¹_, respectively. The enhanced photocatalytic activities of Ag/AgI/CN-4 composite might be attributed to the synergistic effect between Ag/AgI nanoparticles and g-C₃N₄ and the localized surface plasmon resonance effect of metallic Ag. Moreover, Ag/AgI/CN-4 composite showed excellent recyclability and stability after five cycling photocatalytic tests (about 25 h). Furthermore, the possible photocatalytic mechanism of Ag/AgI/CN composites is proposed.     

Synergistic effects of multiple heterojunctions significantly enhance the photocatalytic H2 evolution rate CdS/La2Ti2O7/NiS2 ternary composites

Novel CdS/La₂Ti₂O₇/NiS₂ ternary composite photocatalysts without noble metal were successfully constructed by a simple hydrothermal method. Under visible light irradiation (λ > 400 nm), the optimal CdS/La₂Ti₂O₇/NiS₂ composite produced H₂ at a rate of about 12.77 mmol g⁻¹ h⁻¹, which was 84 times as high as that of pure CdS. This performance enhancement can be attributed to the formation of multiple heterojunctions (including CdS/NiS₂, CdS/La₂Ti₂O₇ and CdS/La₂Ti₂O₇/NiS₂ interface structures) between the three components in the as-prepared CdS/La₂Ti₂O₇/NiS₂ composites. The formed multiple heterojunctions help to separate electron-hole pairs more quickly and efficiently, thus greatly increasing the photocatalytic activity of the CdS/La₂Ti₂O₇/NiS₂ composites. This is very important for the utlization of solar energy for water splitting.     

Rationally designed ternary CdSe/WS2/g-C3N4 hybrid photocatalysts with significantly enhanced hydrogen evolution activity and mechanism insight

Excellent light harvest, efficient charge separation and sufficiently exposed surface active sites are crucial for a given photocatalyst to obtain excellent photocatalytic performances. The construction of two-dimensional/two-dimensional (2D/2D) or zero-dimensional/2D (0D/2D) binary heterojunctions is one of the effective ways to address these crucial issues. Herein, a ternary CdSe/WS₂/g-C₃N₄ composite photocatalyst through decorating WS₂/g-C₃N₄ 2D/2D nanosheets (NSs) with CdSe quantum dots (QDs) was developed to further increase the light harvest and accelerate the separation and migration of photogenerated electron-hole pairs and thus enhance the solar to hydrogen conversion efficiency. As expected, a remarkably enhanced photocatalytic hydrogen evolution rate of 1.29 mmol g⁻¹ h⁻¹ was obtained for such a specially designed CdSe/WS₂/g-C₃N₄ composite photocatalyst, which was about 3.0, 1.7 and 1.3 times greater than those of the pristine g-C₃N₄ NSs (0.43 mmol g⁻¹ h⁻¹), WS₂/g-C₃N₄ 2D/2D NSs (0.74 mmol g⁻¹ h⁻¹) and CdSe/g-C₃N₄ 0D/2D composites (0.96 mmol g⁻¹ h⁻¹), respectively. The superior photocatalytic performance of the prepared ternary CdSe/WS₂/g-C₃N₄ composite could be mainly attributed to the effective charge separation and migration as well as the suppressed photogenerated charge recombination induced by the constructed type-II/type-II heterojunction at the interfaces between g-C₃N₄ NSs, CdSe QDs and WS₂ NSs. Thus, the developed 0D/2D/2D ternary type-II/type-II heterojunction in this work opens up a new insight in designing novel heterogeneous photocatalysts for highly efficient photocatalytic hydrogen evolution.     

Hollow heterostructure CoS/CdS photocatalysts with enhanced charge transfer for photocatalytic hydrogen production from seawater

In recent years, there have been many studies on photocatalytic water splitting, but there are still few high-efficiency photocatalysts for photocatalytic seawater splitting. In this study, a series of hollow Co sulphide-supported CdS catalyst (H–CoS/CdS) composite photocatalysts were prepared by loading CdS onto the surface of H–CoS, which can be used for efficient H₂ production in pure water and simulated seawater. The heterojunction H–CoS/CdS exhibited H₂ production of 572.4 μmol g^?1 (4 h) from simulated seawater, which is 97.7 and 2.96 times those of H–CoS and CdS, respectively. The h-CoS cocatalyst extended the light absorption range of CdS, improved the chemical stability, and significantly enhances the charge separation efficiency. This study provides guidance for the reasonable design of a photocatalytic seawater-based H₂ production catalyst with high efficiency and low cost.     

Boosting hydrogen evolution under simulated sunlight via constructing close electron transfer interface between 1D CdxZn1-xS nanorod and 2D MoS2@MoOy nanosheet

Designing an efficient non-noble metal photocatalyst, which utilizes solar energy, has great potential to produce clean energy hydrogen. The microstructural refinement of 1D Cd_0.2Zn_0.8S nanorod was induced by doping with 2D MoS₂@MoO_y layer during microwave hydrothermal treatment. The maximum H₂ production rate of the composite prepared at optimum conditions was 186 mmol g⁻¹ h⁻¹, which increased by 34.8% compared with that of Cd_0.2Zn_0.8S (138 mmol g⁻¹ h⁻¹). The apparent quantum yields of the optimized composite were 10.3% and 15.6% at 365 and 420 nm, respectively. The tight S-scheme heterojunction contributed to the separation of photogenerated electron-hole pairs effectively, as confirmed by the characterization analysis of ·OH and ·O⁻₂ radicals, surface potential under illumination and darkness and in situ XPS spectra. Moreover, the active species of sulfur coordinated-Mo⁵⁺ as low-coordinate center promoted the dissociation of water and decreased the over potential of H₂ production. Furthermore, the optimal composite showed excellent stable catalytic activity for hydrogen evolution, and the H₂ production rate was 176.7 mmol g⁻¹ h⁻¹ after five cycles (95% of the first cycle). Overall, this work provides a promising strategy for improving the effectiveness of H₂ production by preparing non-noble metal composite photocatalysts.     

Enhanced photocatalytic hydrogen evolution over semi-crystalline tungsten phosphide

Increasing the separation efficiency and transfer rate of photogenerated charges is the dominant factor for improving photocatalytic activity. Herein, we successfully prepared semi-crystalline WP (SC-WP) with good optical properties and as a cocatalyst to modify CdS nanorods (CdS NRs) to construct SC-WP/CdS (PD) composite catalyst by simple electrostatic self-assembly method for photocatalytic hydrogen evolution. Two high-efficiency and stable photocatalytic hydrogen evolution systems were constructed with 1.0 M ammonium sulfite solution and 10 vol% lactic acid solution as sacrificial agents, respectively. Surprisingly, the maximum photocatalytic H₂ production rate of 15446.21 μmol h⁻¹ g⁻¹ is obtained over 10PD composite, which is 10.58 times greater than that of pure CdS. The improved photocatalytic activity can be attributed to the fact that the SC-WP nanoparticles provides a large number of exposed active sites on the surface of CdS for hydrogen evolution reaction, which can efficiently capture photogenerated electrons from CdS nanorods and promotes the transport and separation of light-induced charges. And the introduction of SC-WP nanoparticles with excellent optical properties can efficiently improve the visible light absorption range and the utilization rate of the absorbed light of the PD composite. In addition, the SC-WP nanoparticles show semi-crystalline state, which is also conducive to enhancing the photocatalytic activity.     

Nanoparticle metal Ni cocatalyst on NiTe2 microsphere for improved photocatalytic hydrogen evolution

Scalable and sustainable photocatalytic hydrogen evolution via water splitting requires highly active, stable and earth-abundant cocatalysts to replace rare and expensive metal Platinum. Herein, two facile and similar thermal injection methods are employed to synthesize 3D NiTe₂ microsphere and 0D/3D Ni/NiTe₂ Schottky heterojunction photocatalyst. The optimized 6% Ni/NiTe₂ composite shows good H₂ evolution activity with a rate of 2214.2 μmol g⁻¹·h⁻¹- about 1.55 times higher than that of single NiTe₂. Especially, it is the first time to report that NiTe₂ and Ni/NiTe₂ composite have the activity of producing H₂O₂ through the two-electron reduction of O₂ during photocatalytic water splitting. This enhanced photocatalytic performance can be attributed to the rapid separation and migration of photogenerated charge carriers, low interfacial resistance, abundant surface active sites and two-electron reduction reaction process. This work provides an innovative approach for designing and constructing the potential metal-semiconductor composites with unique electronic structures.     

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.