Photocatalyst For Hydrogen Evolution Research Articles

Synergistic effect of carbon dopants on photoinduced water−splitting on graphitic carbon nitride

Graphitic carbon nitride (g-CN), composed of heptazines, holds promise as a photocatalyst for hydrogen evolution. But its suboptimal visible light absorption and poor electrical conductivity limit photocurrent density and catalytic activity. Carbon atom doping, specifically carbon-modified g-CN (C/g-CN), enhances photocatalytic performance. This study investigates the impact of carbon dopants at the three-coordinated nitrogen atom (N3C) and the two-coordinated nitrogen atom (N2C) sites on the reaction mechanism of water-splitting in the ground and excited states. Nonadiabatic dynamics simulations are employed on water hydrogen-bonded to C-doped heptazines (H2O⋯C/heptazine) to unveil the molecular-level decomposition mechanism in the excited states. The simulations reveal that the C dopants at N2C improve the activity for water-splitting in the ground state. The C dopants at N3C improve the H atom detachment from H2O via the electron-driven proton transfer (EDPT) process. The synergistic effect of carbon dopants on enhanced catalytic activity of C/g-CN is elucidated.

Symmetry‐breaking of Dibenzo[b,d]thiophene Sulfone Enhancing Polaron Generation for Boosted Photocatalytic Hydrogen Evolution

The current bottleneck in the development of efficient photocatalysts for hydrogen evolution is the limited availability of high‐performance acceptor units. Over the past nine years, dibenzo[b,d]thiophene sulfone (DBS) has been the preferred choice for the acceptor unit. Despite extensive exploration of alternative structures as potential replacements for DBS, a superior substitute remains elusive. In this study, a symmetry‐breaking strategy was employed on DBS to develop a novel acceptor unit, BBTT‐1SO. The asymmetric structure of BBTT‐1SO proved beneficial for increasing multiple moment and polarizability. BBTT‐1SO‐containing polymers showed higher efficiencies for hydrogen evolution than their DBS‐containing counterparts by up to 166%. PBBTT‐1SO exhibited an excellent hydrogen evolution rate (HER) of 222.03 mmol g−1 h−1 and an apparent quantum yield of 27.5% at 500 nm. Transient spectroscopic studies indicated that the BBTT‐1SO‐based polymers facilitated electron polaron formation, which explains their superior HERs. PBBTT‐1SO also showed 14% higher HER in natural seawater splitting than that in deionized water splitting. Molecular dynamics simulations highlighted the enhanced water‐PBBTT‐1SO polymer interactions in salt‐containing solutions. This study presents a pioneering example of a substitute acceptor unit for DBS in the construction of high‐performance photocatalysts for hydrogen evolution.

Construction of Inverse-Opal ZnIn2S4 with Well-Defined 3D Porous Structure for Enhancing Photocatalytic H2 Production.

The conversion of solar energy into hydrogen using photocatalysts is a pivotal solution to the ongoing energy and environmental challenges. In this study, inverse opal (IO) ZnIn2S4 (ZIS) with varying pore sizes is synthesized for the first time via a template method. The experimental results indicate that the constructed inverse opal ZnIn2S4 has a unique photonic bandgap, and its slow photon effect can enhance the interaction between light and matter, thereby improving the efficiency of light utilization. ZnIn2S4 with voids of 200 nm (ZIS-200) achieved the highest hydrogen production rate of 14.32 μ mol h-1. The normalized rate with a specific surface area is five times higher than that of the broken structures (B-ZIS), as the red edge of ZIS-200 is coupled with the intrinsic absorption edge of the ZIS. This study not only developed an approach for constructing inverse opal multi-metallic sulfides, but also provides a new strategy for enriching efficient ZnIn2S4-based photocatalysts for hydrogen evolution from water.

Hydrothermally Synthesized ZnCr- and NiCr-Layered Double Hydroxides as Hydrogen Evolution Photocatalysts.

The layered double hydroxides (LDHs) of transition metals are of great interest as building blocks for the creation of composite photocatalytic materials for hydrogen production, environmental remediation and other applications. However, the synthesis of most LDHs is reported only by the conventional coprecipitation method, which makes it difficult to control the catalyst's crystallinity. In the present study, ZnCr- and NiCr-LDHs have been successfully prepared using a facile hydrothermal approach. Varying the hydrothermal synthesis conditions allowed us to obtain target products with a controllable crystallite size in the range of 2-26 nm and a specific surface area of 45-83 m2∙g-1. The LDHs synthesized were investigated as photocatalysts of hydrogen generation from aqueous methanol. It was revealed that the photocatalytic activity of ZnCr-LDH samples grows monotonically with the increase in their average crystallite size, while that of NiCr-LDH ones reaches a maximum with intermediate-sized crystallites and then decreases due to the specific surface area reduction. The concentration dependence of the hydrogen evolution activity is generally consistent with the standard Langmuir-Hinshelwood model for heterogeneous catalysis. At a methanol content of 50 mol. %, the rate of hydrogen generation over ZnCr- and NiCr-LDHs reaches 88 and 41 μmol∙h-1∙g-1, respectively. The hydrothermally synthesized LDHs with enhanced crystallinity may be of interest for further fabrication of their nanosheets being promising components of new composite photocatalysts.

Construction of flexible BiOBr/W18O49/polyacrylonitrile discrete heterojunction nanofibers as a dual-functional photocatalyst for simultaneous hydrogen evolution and organic pollutant degradation

Dual-functional photocatalysis has attracted increasing attention due to its ability to achieve efficient synergistic hydrogen (H2) evolution and pollutant removal. Energy band structure engineering and surface morphology modification of photocatalysts is a useful strategy to improve the activity of photocatalysis. This paper uses a combination of electrospinning technology and hydrothermal method to prepare flexible BiOBr/W18O49/PAN discrete heterojunction flexible nanofibers (NFs) with staggered energy bands and spatially separated redox surfaces. The BiOBr/W18O49 heterojunction can improve carrier separation and migration, as evidenced by the photoluminescence and photoelectrochemical experiments. The localized surface plasmon resonance (LSPR) effect of W18O49 can achieve injection of “hot electrons” and lead to expanding the light absorption range according to the UV–visible-near infrared diffuse reflection spectra results. The discrete structure of BiOBr/W18O49/PAN NFs can provide spatially separated active sites for simultaneous photocatalytic redox reaction. As expected, the BiOBr/W18O49/PAN discrete heterojunction NFs greatly enhance the photocatalytic activity in simultaneous dual-functional reaction for H2 evolution and RhB degradation. The highest simultaneous H2 evolution rate and RhB degradation rate of BiOBr/W18O49/PAN NFs are 31.7 times and 34.1 times of BiOBr/PAN, respectively. The design and construction of this flexible discrete heterojunction NFs structures can provide novel ideas and directions for simultaneous dual-functional photocatalysts.

NH4Cl-assisted synthesis of TaON nanoparticle applied to photocatalytic hydrogen and oxygen evolution from water

Oxynitride semiconductors are promising photocatalyst materials for visible light-driven water splitting, while the synthesis of well crystalized oxynitride still remains challenge. In present work, narrow-bandgap TaON nanoparticles are synthesized via heating a vacuum-sealed mixture of KTaO3, Ta and NH4Cl. This method possesses multiple advantages in terms of lower calcination parameter, higher N conversion efficiency and superior photocatalytic activity in comparison with the traditional thermal ammonolysis using NH3 gas as a nitrogen source. Through the analysis of intermediates produced upon the elevation of heating temperature, a gas–solid-phase reaction between TaCl5 and Ta2O5 is demonstrated as the final step, which is conducive to decreasing thermal energy barrier and accelerating nitridation process. Precise control of preparation conditions, including calcination temperature and duration, allows for the regulation of surface O/N ratio of TaON particles to unity, resulting in optimized photocatalytic activity. Photoelectrochemical assessment and intensity modulated photocurrent spectroscopy provide convincing evidence for improved charge transfer efficiency of photoexcited holes at TaON surface. A Z-scheme overall water splitting is accomplished by employing the TaON as an effective oxygen evolution photocatalyst, SrTiO3:Rh as a hydrogen evolution photocatalyst, and reduced graphene oxide (rGO) as a solid-state electron mediator. This work presents a promising strategy for the synthesis of high-quality oxynitride materials in application to photocatalytic water splitting.

Accelerated discovery of molecular nanojunction photocatalysts for hydrogen evolution by using automated screening and flow synthesis

Discovering and optimizing multicomponent organic semiconductors is typically a laborious process. High-throughput experimentation can accelerate this, but the results of small-scale screening trials are not always transferable to bulk materials production. Here we report the accelerated discovery of molecular nanojunction photocatalysts based on a combinatorial donor–acceptor molecular library assisted by high-throughput automated screening. The knowledge gained from this high-throughput batch screening is then transferred to a scaled-up, flow-based synthesis process. The scaled-up molecular nanojunction MTPA-CA:CNP147 (3-(4-(bis(4-methoxyphenyl)amino)phenyl)-2-cyanoacrylic acid:2,6-bis(4-cyanophenyl)-4-(4′-fluoro-[1,1′-biphenyl]-4-yl)pyridine-3,5-dicarbonitrile) exhibits a sacrificial hydrogen evolution rate of 330.3 mmol h−1 g−1 with an external quantum efficiency of 80.3% at 350 nm, which are among the highest reported for an organic photocatalyst. A one-dimensional nanofibre architecture is identified for this molecular nanojunction, which exhibits efficient charge separation. Electronic structure–property correlations across the photocatalyst library show that a moderate binding energy between the donor and the acceptor molecules is a potential factor for efficient molecular nanojunction formation.

Cobalt Oxide on Boron-Doped Graphitic Carbon Nitride as Bifunctional Photocatalysts for CO2 Reduction and Hydrogen Evolution.

In this work, the prepared cobalt oxide decorated boron-doped g-C3N4 (CoOx/g-C3N4) heterojunction exhibits remarkable activity in CO2 reduction (CO2RR), resulting in high yields of CH3COOH (∼383 μmol·gcatalyst-1) and CH3OH (∼371 μmol·gcatalyst-1) with 58% selectivity to C2+ under visible light. However, the same system leads to high H2 evolution (HER) by increasing the cobalt oxide content, suggesting that the selectivity and preference for the CO2RR or HER depend on oxide decoration. By comparing HER and CO2RR evolution in the same system, this work provides critical insights into the catalytic mechanism, indicating that the CoOx/g-C3N4 heterojunction formation is necessary to foster high visible light photoactivity.

Nanoparticulate TiN Loading to Promote Z-Scheme Water Splitting Using a Narrow-Bandgap Nonoxide-Based Photocatalyst Sheet.

Some oxide-based particulate photocatalyst sheets exhibit excellent activity during the water-splitting reaction. The replacement of oxide photocatalysts with narrow-bandgap photocatalysts based on nonoxides could provide the higher solar-to-hydrogen energy conversion efficiencies that are required for practical implementation. Unfortunately, the activity of nonoxide-based photocatalyst sheets is low in many cases, indicating the need for strategies to improve the quality of nonoxide photocatalysts and the charge transfer process. In this work, single-crystalline particulate SrTaO2 N is studied as an oxygen evolution photocatalyst for photocatalyst sheets applied to Z-scheme water splitting, in combination with La5 Ti2 Cu0.9 Ag0.1 O7 S5 and Au as the hydrogen evolution photocatalyst and conductive layer, respectively. The loading of SrTaO2 N with CoOx provided increases activity during photocatalytic water oxidation, giving an apparent quantum yield of 15.7% at 420nm. A photocatalyst sheet incorporating CoOx -loaded SrTaO2 N is also found to promote Z-scheme water splitting under visible light. Notably, the additional loading of nanoparticulate TiN on the CoOx -loaded SrTaO2 N improves the water splitting activity by six times because the TiN promotes electron transfer from the SrTaO2 N particles to the Au layer. This work demonstrates key concepts related to the improvement of nonoxide-based photocatalyst sheets based on facilitating the charge transfer process through appropriate surface modifications.

Overcoming small-bandgap charge recombination in visible and NIR-light-driven hydrogen evolution by engineering the polymer photocatalyst structure

Designing an organic polymer photocatalyst for efficient hydrogen evolution with visible and near-infrared (NIR) light activity is still a major challenge. Unlike the common behavior of gradually increasing the charge recombination while shrinking the bandgap, we present here a series of polymer nanoparticles (Pdots) based on ITIC and BTIC units with different π-linkers between the acceptor-donor-acceptor (A-D-A) repeated moieties of the polymer. These polymers act as an efficient single polymer photocatalyst for H2 evolution under both visible and NIR light, without combining or hybridizing with other materials. Importantly, the difluorothiophene (ThF) π-linker facilitates the charge transfer between acceptors of different repeated moieties (A-D-A-(π-Linker)-A-D-A), leading to the enhancement of charge separation between D and A. As a result, the PITIC-ThF Pdots exhibit superior hydrogen evolution rates of 279 µmol/h and 20.5 µmol/h with visible (>420 nm) and NIR (>780 nm) light irradiation, respectively. Furthermore, PITIC-ThF Pdots exhibit a promising apparent quantum yield (AQY) at 700 nm (4.76%).

Enhanced photocatalytic activity in H2 production from methanol aqueous solution based on the synthesized Pt-TiO2-decorated MoSe2 nanocomposites

In this work, a simple hydrothermal method to synthesize a ternary nanocomposite of Pt-TiO2 decorated on MoSe2 as a photocatalyst for hydrogen (H2) evolution from an aqueous methanol solution. The-as prepared Pt-TiO2/MoSe2 nanocomposite were characterized by XRD, Raman spectra, electron microscopy (FE-SEM/Mapping and HR-TEM), XPS UV-Vis and PL analysis. XRD patterns confirmed the presence of MoSe2 and Pt-TiO2 crystal phases in the Pt-TiO2/MoSe2 nanocomposite. Raman spectra displayed characteristic peaks corresponding to Mo-Se out-of-plane vibration and Pt-TiO2 vibration modes, confirming the successful synthesis of Pt-TiO2/MoSe2 nanocomposite. FE-SEM images showed a sheet-like morphology for MoSe2-NS and spherical Pt/TiO2 particles, with MoSe2 sparsely scattered on the Pt-TiO2 surface with EDS mapping confirmed even element distribution of Pt-TiO2/MoSe2 nanocomposite. TEM images revealed the transparent nature of MoSe2-NS with well-resolved lattice fringes. Pt-TiO2 exhibited uniform dispersion of Pt nanoparticles on TiO2, and the Pt-TiO2/MoSe2 nanocomposite showed integration of MoSe2-NS with Pt-TiO2. HRTEM images confirmed the lattice fringes of MoSe2-NS, Pt, and TiO2 particles. Tauc plot measurements revealed optical band gaps of 2.99 eV for MoSe2-NS, 3.19 eV for Pt-TiO2, and 2.78 eV for Pt-TiO2/MoSe2. XPS analysis confirmed the presence of Mo, Se, Pt, Ti, O, and C elements in the Pt-TiO2/MoSe2 nanocomposite. Based on the photoelectrochemical measurements, the Pt-TiO2/MoSe2 nanocomposite show the lower onset overpotential of 123 mV, which is much higher than Pt-TiO2 (179 mV) and MoSe2 (213 mV) at 10 mA/cm2. The photocatalytic efficiency of Pt-TiO2/MoSe2 nanocomposite in the context of H2 production through the enhancement of aqueous methanol under visible light exposure was assessed across different factors. Among these, the Pt-TiO2/MoSe2 nanocomposite exhibited the highest photoactivity in H2 production at 1337 μmolg−1 after 4 h. These results show the promising potential of the Pt-TiO2/MoSe2 nanocomposite catalyst in addressing both environmental and energy challenges in the future.

Cu doping enhanced ZnIn2S4/TiO2(VO) Z-scheme heterojunction for efficient photocatalytic overall water splitting

The design and synthesis of efficient photocatalysts for overall water splitting is a promising research topic. By reasonable modification, the hydrogen evolution photocatalyst can have the ability for overall water splitting. Both ZnIn2S4 and TiO2 have shown great potential in the field of photocatalytic hydrogen evolution, but their use for efficient overall water splitting is challenging. In this work, a Z-scheme heterojunction material of Cu-doped ZnIn2S4 composite TiO2 with rich oxygen vacancies was synthesized. Cu doping enhanced the light absorption, reduced the bandgap, and improved photocatalytic activity. In addition, the oxygen vacancies in TiO2 were conducive to the separation and migration of electron-hole pairs, and the construction of a Z-scheme heterojunction between ZnIn2S4 and TiO2 can also effectively promote the separation and migration of carriers. Therefore, the photocatalytic activity of this material was significantly improved and exhibited excellent overall water splitting activity without any sacrificial agents and co-catalysts. The optimized hydrogen and oxygen evolution rates were 589.64 μmol/g/h and 292.75 μmol/g/h, respectively. This work provided favorable evidence for metal element doping to promote the photocatalytic activity of composite heterojunction materials and provided a new strategy for the development of heterojunction photocatalysts for overall water splitting.

Coupling Z-Scheme g-C3N4/rGO/MoS2 Ternary Heterojunction as an Efficient Visible Light Photocatalyst for Hydrogen Evolution and RhB Degradation.

Coupling heterostructures to synergistically improve the light adsorption and promote the charge carrier separation has been regarded as an operative approach to advance the photocatalytic performances. However, it is still challenging to construct heterostructures with appropriate optical properties and interfacial energy structures at the same time. In this work, a Z-scheme g-C3N4/rGO/MoS2 ternary composite photocatalyst is successfully synthesized via an effective hydrothermal method. The as-synthesized g-C3N4/rGO/MoS2 composite photocatalyst exhibited significant improvement for visible light absorption and boosted the separation efficiency of photoinduced electron-hole pairs. The g-C3N4/rGO/MoS2 system exhibited optimum visible-light-induced photocatalytic activity in hydrogen (H2) from water splitting and degrading pollutant rhodamin B (RhB), which is 22 times and 5 times higher than that of pure g-C3N4, respectively. The excellent photocatalytic activities are attributed to the synergetic effects of coupling rGO, g-C3N4, and MoS2 ternary structures to the composite photocatalyst. These combinations of intimate two-dimensional nanoconjugations can effectively inhibit charge recombination and accelerate charge transfer kinetics, forming a Z-scheme-assisted photocatalytic mechanism, thereby exhibiting superior photocatalytic activity.

Efficient and stable visible-light-driven Z-scheme overall water splitting using an oxysulfide H2 evolution photocatalyst

So-called Z-scheme systems permit overall water splitting using narrow-bandgap photocatalysts. To boost the performance of such systems, it is necessary to enhance the intrinsic activities of the hydrogen evolution photocatalyst and oxygen evolution photocatalyst, promote electron transfer from the oxygen evolution photocatalyst to the hydrogen evolution photocatalyst, and suppress back reactions. The present work develop a high-performance oxysulfide photocatalyst, Sm2Ti2O5S2, as an hydrogen evolution photocatalyst for use in a Z-scheme overall water splitting system in combination with BiVO4 as the oxygen evolution photocatalyst and reduced graphene oxide as the solid-state electron mediator. After surface modifications of the photocatalysts to promote charge separation and redox reactions, this system is able to split water into hydrogen and oxygen for more than 100 hours with a solar-to-hydrogen energy conversion efficiency of 0.22%. In contrast to many existing photocatalytic systems, the water splitting activity of the present system is only minimally reduced by increasing the background pressure to 90 kPa. These results suggest characteristics suitable for applications under practical operating conditions.

Twinned crystal Cd0.9Zn0.1S/MoO3 nanorod S-scheme heterojunctions as promising photocatalysts for efficient hydrogen evolution.

Leveraging solar energy through photocatalytic hydrogen production from water stands out as one of the most promising approaches to address the energy and environmental challenges. The choice of catalyst profoundly influences the outcomes of photocatalytic reactions, and constructing heterojunctions has emerged as a widely applied strategy to overcome the limitations associated with single-phase photocatalysts. MoO3, renowned for its high chemical stability, encounters issues such as low photocatalytic efficiency and fast recombination of photogenerated electrons and holes. To tackle these challenges, the morphology of MoO3 has been controlled to form nanorods, simultaneously suppressing the aggregation of the catalyst and increasing the number of surface-active sites. Moreover, to facilitate the separation of photogenerated charge carriers, Cd0.9Zn0.1S nanoparticles with a twin crystal structure are deposited on the surface of MoO3, establishing an S-scheme heterojunction. Experimental findings demonstrate that the synergistic effects arising from the well-defined morphology and interface interactions extend the absorption range to visible light response, improve charge transfer activity, and prolong the lifetime of charge carriers. Consequently, Cd0.9Zn0.1S/MoO3 S-scheme heterojunctions exhibit outstanding photocatalytic hydrogen production performance (3909.79 μmol g-1 h-1) under visible light irradiation, surpassing that of MoO3 by nearly nine fold.

Fluorinated carbon encapsulated NiO cluster/TiO2 nanotubes as a robust photocatalyst for hydrogen evolution

Theoretical predictions directed modulations on work function, kinetics of interfacial charge transfer and surface hydrogen binding from NiO cluster and highly electronegative surface encapsulation allow significant increases in HER performance.

Prussian blue analogues-derived 2D NiCo@C bimetals grown on g-C3N4 as photocatalysts for hydrogen evolution

The development of highly active and stable cocatalysts using earth-abundant transition metals to replace noble metals is important for the application of photocatalytic hydrogen production technology. In this study, two-dimensional (2D) carbon-encapsulated NiCo bimetallic nanosheets (NiCo@C) was designed for the first time as a new co-catalyst to synergistically combine with graphitic carbon nitride (g-C3N4) and promote its hydrogen evolution. The NiCo@C cocatalysts were using an innovative molten salt method by using nickel hexacyanocobaltate Ni3[Co(CN)6]2 (Ni-Co PBA) nanocubes as precursor. The Ni-Co PBA nanocubes undergo dissolution growth and salt templating processes to form bimetallic 2D nanosheets during charring in molten salt media, and combine with 2D g-C3N4 to form NiCo@C/g-C3N4 photocatalyst. The optimized NiCo@C/g-C3N4 photocatalyst significantly improved the H2 evolution activity, and the H2 evolution rate reached 3791.07 μmol·g−1·h−1, which was 5 times higher than that of the particle CoNi/g-C3N4 (636.89 μmol·g−1·h−1). The H2 evolution activity was also comparable to that of the photocatalytic activity of 1.0% Pt/g-C3N4 system, indicating that the earth-abundant NiCo@C can replace noble metal as a cocatalyst to significantly enhance the photocatalytic performance of 2D photocatalysts. The conversion of three-dimensional Ni-Co PBA into carbon-coated 2D metal nanosheets by molten salt-assisted pyrolysis provides a feasible approach to explore the synthesis and design of efficient and robust non-precious metal catalysts.

(Invited) Plasmonic Aerogels for Gas-Phase Photocatalytic Reactions

As a special form of material, aerogel has emerged as a promising type of photocatalyst. Owing to the large specific surface area and the developed pore texture, it would be suitable to drive various gas-phase reactions such as CO2 reduction and CH4 conversion. More importantly, the size of the fundamental building blocks in an aerogel, which is typically 5-20 nm, is approaching that of the noble metals with the surface plasmon resonance (SPR) effect. Innovated by Rolison and Niederberger(1, 2), aerogels with plasmonic effect have been extensively studied as photocatalysts for hydrogen evolution and dye degradation in liquid mediumThis talk then aims to introduce some of our recent results on the construction and evaluation of plasmonic noble metal/ceria composite aerogels, which cover the content from the synthesis to new applications. Modified synthesis methods are developed for the rational incorporation of plasmonic metal nanoparticles such as Ag and Au into an aerogel backbone in one step, which offers an alternative route to tune the composition and size of these nanoparticles, or even building single-atom composite aerogels in the conventional sol-gel methodology(3). When these plasmonic aerogel photocatalysts are applied for gas-phase CO2 reduction and non-oxidative CH4 coupling reaction, good performance is observed. The synergistic effect of plasmonic sensitizer and co-catalyst is discussed and is responsible for the performance enhancement. P. A. DeSario, J. J. Pietron, A. Dunkelberger, T. H. Brintlinger, O. Baturina, R. M. Stroud, J. C. Owrutsky and D. R. Rolison, Langmuir, 33, 9444 (2017). F. Rechberger and M. Niederberger, Nanoscale Horizons, 2, 6 (2017). M. Wu, C. Ouyang, Z. Ye, S. Li, Z. Hong and M. Zhi, ACS Applied Energy Materials, 5, 7335 (2022).

Heterojunction Engineering of Multinary Metal Sulfide-Based Photocatalysts for Efficient Photocatalytic Hydrogen Evolution.

Photocatalytic hydrogen evolution (PHE) via water splitting using semiconductor photocatalysts is an effective path to solve the current energy crisis and environmental pollution. Heterojunction photocatalysts, containing two or more semiconductors, exhibit better PHE rates than those with only one semiconductor owing to the altered band alignment at the interface and stronger driving force for charge separation. Traditional binary metal sulfide (BMS)-based heterojunction photocatalysts, such as CdS, MoS2 , and PbS, demonstrate excellent PHE performance. However, the recently developed multinary metal sulfide (MMS)-based photocatalysts possess favorable chemical stability, tunable band structure, and flexible element compositions, and have considerable potential to realize higher PHE rates than those of BMSs. In this review article, the mechanism of PHE is first elucidated and then various single and heterojunction MMS-based photocatalysts and their charge transfer behaviors and PHE performances are systematically summarized. A perspective on potential future research directions in this field is concluded.

Development of a novel ternary FeWO4/CoP/Mn0.5Cd0.5S composite photocatalyst for photocatalytic hydrogen evolution in watersplitting

The construction of a non-homogeneous photocatalyst system with the advantages of both efficient photogenerated charge separation efficiency and abundant number of active sites remains a major challenge in the field of photocatalysis. A new ternary MnCdS-based photocatalyst combined with FeWO4 and CoP modifications was successfully prepared by chemical precipitation and thermal reduction methods. The ternary FeWO4/CoP/Mn0.5Cd0.5S photocatalyst exhibited a maximum hydrogen evolution activity of 30.45 mmol⋅g−1⋅h−1, which was 6.86 times higher than that of pureMn0.5Cd0.5S. The enhancement of the hydrogen production performance of the FeWO4/CoP/Mn0.5Cd0.5Sphotocatalyst was attributed to the p-n heterojunction constructed at the interface of FeWO4 and Mn0.5Cd0.5S, which strengthened the charge separation ability of the system. On the other hand, the decoration of CoP remarkably diminishes the hydrogen evolution potential of the system and supplies richer active sites for the catalytic reaction.