Efficient Solar Light Harvesting CdS/Co9 S8 Hollow Cubes for Z-Scheme Photocatalytic Water Splitting

Construction of Ag/Ag2S/CdS Heterostructures through a Facile Two-Step Wet Chemical Process for Efficient Photocatalytic Hydrogen Production

We have demonstrated a two-step wet chemical approach for synthesizing ternary Ag/Ag₂S/CdS heterostructures for efficient photocatalytic hydrogen evolution. The CdS precursor concentrations and reaction temperatures are crucial in determining the efficiency of photocatalytic water splitting under visible light excitation. In addition, the effect of operational parameters (such as the pH value, sacrificial reagents, reusability, water bases, and light sources) on the photocatalytic hydrogen production of Ag/Ag₂S/CdS heterostructures was investigated. As a result, Ag/Ag₂S/CdS heterostructures exhibited a 3.1-fold enhancement in photocatalytic activities compared to bare CdS nanoparticles. Furthermore, the combination of Ag, Ag₂S, and CdS can significantly enhance light absorption and facilitate the separation and transport of photogenerated carriers through the surface plasma resonance (SPR) effect. Furthermore, the Ag/Ag₂S/CdS heterostructures in seawater exhibited a pH value approximately 2.09 times higher than in de-ionized water without an adjusted pH value under visible light excitation. The ternary Ag/Ag₂S/CdS heterostructures provide new potential for designing efficient and stable photocatalysts for photocatalytic hydrogen evolution.

Synthesis of Two Porous CdS Rods by Anion Exchange Method and Their Photocatalytic Properties

Semiconductor materials with pore structure have excellent physicochemical properties for photocatalytic reactions. Here, the one-step vulcanization of Cd-based MOF solid rods was successfully developed to synthesize two kinds of CdS rods with pore structure: hollow rods (HRs) and mesoporous rods (MRs). Among the three catalysts, the CdS HRs showed the highest photocatalytic efficiency, which could remove about 96.0% of RhB in 30 min under visible light irradiation. The enhanced photocatalytic activity of CdS HRs benefits from its novel hollow structure, which enhances the visible light absorption capability and the separation efficiency of photogenerated electron-hole pairs. The successful synthesis of CdS HRs has guiding significance for the design and synthesis of other hollow structures with high photocatalytic activity.

COF-5/CoAl-LDH Nanocomposite Heterojunction for Enhanced Visible-Light-Driven CO2 Reduction

Photocatalytic conversion of CO₂ into value-added chemical fuels is an attractive route to mitigate global warming and the energy crisis. Reasonable design of optical properties and electronic behavior of the photocatalyst are essential to improve their catalytic activity. Herein, the 1D/2D heterojunction by direct in-situ synthesis of the covalent organic framework (COF)-5 colloid on the surface of CoAl layered double hydroxide (LDH) was used as the prospective photocatalyst for CO₂ reduction. COF-5/CoAl-LDH nanocomposite achieved 265.4 μmol g^-1 of CO with 94.6 % selectivity over CH₄ evolution in 5 h under visible light irradiation, which was 4.8 and 2.3 times higher than those of COF-5 colloid and CoAl-LDH, respectively. The enhanced catalytic activity was derived from the increased visible-light activity and the construction of type II-2 heterojunction, which greatly optimized visible light harvesting and accelerated the efficient separation of the photoinduced holes and electrons. This work paves the way for rational design of heterojunction catalysts in photocatalytic CO₂ reduction.

Encapsulating Fe2 O3 Nanotubes into Carbon-Coated Co9 S8 Nanocages Derived from a MOFs-Directed Strategy for Efficient Oxygen Evolution Reactions and Li-Ions Storage

The development of high-efficiency, robust, and available electrode materials for oxygen evolution reaction (OER) and lithium-ion batteries (LIBs) is critical for clean and sustainable energy system but remains challenging. Herein, a unique yolk-shell structure of Fe₂ O₃ nanotube@hollow Co₉ S₈ nanocage@C is rationally prepared. In a prearranged sequence, the fabrication of Fe₂ O₃ nanotubes is followed by coating of zeolitic imidazolate framework (ZIF-67) layer, chemical etching of ZIF-67 by thioacetamide, and eventual annealing treatment. Benefiting from the hollow structures of Fe₂ O₃ nanotubes and Co₉ S₈ nanocages, the conductivity of carbon coating and the synergy effects between different components, the titled sample possesses abundant accessible active sites, favorable electron transfer rate, and exceptional reaction kinetics in the electrocatalysis. As a result, excellent electrocatalytic activity for alkaline OER is achieved, which delivers a low overpotential of 205 mV at the current density of 10 mA cm^-2 along with the Tafel slope of 55 mV dec^-1 . Moreover, this material exhibits excellent high-rate capability and excellent cycle life when employed as anode material of LIBs. This work provides a novel approach for the design and the construction of multifunctional electrode materials for energy conversion and storage.

Rational design of the Z-scheme hollow-structure Co9S8/g-C3N4 as an efficient visible-light photocatalyst for tetracycline degradation

The development of photocatalysts with high catalytic activity that are capable of full utilization of solar energy is a challenge in the field of photocatalysis. Accordingly, in the present study, an efficient Z-scheme cage-structured Co₉S₈/g-C₃N₄ (c-CSCN) photocatalyst was constructed for the degradation of tetracycline antibiotics under visible-light irradiation. The Z-scheme charge-transfer mechanism accelerates the separation of photogenerated charge carriers and effectively improves photocatalytic activity. Moreover, c-CSCN has a hollow structure, allowing light to be reflected multiple times inside the cavity, thereby effectively improving the utilisation efficiency of solar energy. As a result, the photocatalytic activity of c-CSCN is 1.5-, 2.5-, and 5.8-times higher than those of sheet-type Co₉S₈/g-C₃N₄ (s-CSCN), c-Co₉S₈, and g-C₃N₄, respectively, for the degradation of tetracycline. c-CSCN maintains favourable photocatalytic activity over five consecutive degradation cycles, demonstrating its excellent stability. In addition, c-CSCN performs efficient tetracycline removal in different water substrates. Moreover, c-CSCN exhibits excellent ability to remove tetracycline under direct natural sunlight. This work fully demonstrates that c-CSCN has high catalytic activity and the potential for practical application as a wastewater treatment material.

Core–shell carbon colloid sphere@phosphotungstic acid/CdS as a Z-scheme heterojunction with synergistic adsorption, photothermal and photocatalytic performance

Core–shell carbon colloid sphere@phosphotungstic acid/CdS exhibits excellent visible-light-driven photocatalytic performance, which is due to the Z-scheme heterojunction favoring the charge transfer and spatial charge separation and the photothermal effect.

Engineering Heterostructured Nanocatalysts for CO2 Transformation Reactions: Advances and Perspectives

As a conceivable route to achieving anthropological carbon looping, carbon capture and utilization (CCU) technologies employ waste CO₂ as an accessible C1 building block to generate upgraded chemicals or fuels, thereby simultaneously remedying environmental issues and energy crises. However, efficient CO₂ conversion is disfavored by both its thermodynamics and its kinetics. Heterostructured materials with well-controlled interfaces have great potential for enhanced catalytic performance in various CO₂ transformation reactions, owing to the synergistic effects among components, numerous interfacial and/or surface active sites, increased CO₂ adsorption capacity, promoted charge transfer efficiency, and unique physicochemical properties. This Review highlights the state of the art in typical heterostructures, such as core-shell, yolk-shell, Janus, hierarchical (branched and hollow), and 2D/2D layered structures, applied for CO₂ conversion with various energy inputs (radiation, electricity, heat). Fabrication methods of different heterostructures and structure-composition-performance relationships are also discussed concisely. Finally, a brief summary and prospective research directions are provided. The motivation of this Review is to offer instructive information on the applicability of inorganic heterostructures for CO₂ transformation reactions, and it is hoped that further enlightening studies in this field could emerge in the future.

Synthesis of Sulfur-Doped 2D Graphitic Carbon Nitride Nanosheets for Efficient Photocatalytic Degradation of Phenol and Hydrogen Evolution

Sulfur-doped two-dimensional (2D) graphitic carbon nitride nanosheets (2D-SCN) with efficient photocatalytic activity were synthesized via (1) polycondensation of thiourea to form bulk sulfur-doped graphitic carbon nitride (SCN) and (2) followed by thermal oxidative treatment of the prepared SCN via an etching strategy to form 2D-SCN. Sulfur was doped in situ into SCN by using thiourea as the precursor, and the 2D nanosheet structure was obtained during the thermal oxidative etching process. The structural, morphological, and optical properties of the 2D-SCN sample were investigated in detail. Herein, it is shown that the thermal oxidative etching treatment and sulfur doping induced a 2D nanosheet structure (2D-SCN-3h) with a thickness of about 4.0 nm and exposure of more sulfur elements on the surface. The surface area increased from 16.6 m²/g for SCN to 226.9 m²/g. Compared to bulk SCN, a blue shift of the absorption peaks was observed for the obtained 2D-SCN-3h photocatalyst, and the absorption intensity was higher than that of the sulfur-free counterpart (2D-CN). The successful in situ doping of S element into SCN or 2D-SCN-3h samples is beneficial to the introduction of surface N defects and O species. 2D-SCN-3h indicated higher efficiency in photogenerated charge carrier separation and showed the highest reductive activity in photocatalytic splitting of water at a rate of 127.4 μmol/h under simulated solar light irradiation, which was 250 times and 3 times higher than that of SCN and 2D-CN photocatalysts, respectively. The apparent quantum efficiency was estimated to be 8.35% at 420 nm irradiation. The S-C-N bond formed by sulfur doping was beneficial to the charge-transfer process, and this led to higher photocatalytic activity according to partial density of state analysis computed by first-principles methods.

Z-scheme CdS/Co9S8-RGO for photocatalytic hydrogen production

All-solid-state Z-scheme CdS/Co₉S₈-RGO heterostructures are synthesized by a facile one-pot hydrothermal method followed by annealing, which exhibit a H₂ evolution rate up to 4.82 mmol h⁻¹ g⁻¹ and a remarkable stability due to an efficient charge transfer and separation.

Morphology-preserved transformation of CdS hollow structures toward photocatalytic H2 evolution

Hollow-structured nanomaterials with complex interiors have drawn a great deal of attention due to their unique properties in various fields.

Hollow Nanostructures for Photocatalysis: Advantages and Challenges

Photocatalysis for solar-driven reactions promises a bright future in addressing energy and environmental challenges. The performance of photocatalysis is highly dependent on the design of photocatalysts, which can be rationally tailored to achieve efficient light harvesting, promoted charge separation and transport, and accelerated surface reactions. Due to its unique feature, semiconductors with hollow structure offer many advantages in photocatalyst design including improved light scattering and harvesting, reduced distance for charge migration and directed charge separation, and abundant surface reactive sites of the shells. Herein, the relationship between hollow nanostructures and their photocatalytic performance are discussed. The advantages of hollow nanostructures are summarized as: 1) enhancement in the light harvesting through light scattering and slow photon effects; 2) suppression of charge recombination by reducing charge transfer distance and directing separation of charge carriers; and 3) acceleration of the surface reactions by increasing accessible surface areas for separating the redox reactions spatially. Toward the end of the review, some insights into the key challenges and perspectives of hollow structured photocatalysts are also discussed, with a good hope to shed light on further promoting the rapid progress of this dynamic research field.

3D Branched Ca-Fe2 O3 /Fe2 O3 Decorated with Pt and Co-Pi: Improved Charge-Separation Dynamics and Photoelectrochemical Performance

The construction of junctions on hematite is an effective way to overcome the problems of slow charge separation and transfer kinetics, but constructing the junction is a significant challenge in photoelectrochemical (PEC) water splitting. Herein, a considerable improvement in PEC performance for α-Fe₂ O₃ was achieved following the introduction of a p-n homojunction between n-type α-Fe₂ O₃ and p-type Ca-doped α-Fe₂ O₃ through a facile hydrothermal method. The resultant 3D branched Ca-Fe₂ O₃ /Fe₂ O₃ enhanced the absorption intensity and reached a photocurrent density of 2.14 mA cm^-2 at 1.23 V vs. reversible hydrogen electrode (RHE). The merit of the desired lattice matching of the buried p-n homojunction structure built an internal electric field, which led to appropriate band alignment. These results were supported by a series of photoelectrochemical measurements, in particular, surface photovoltage (SPV) measurements. For further improvement of the charge-separation efficiency, a combination of separated cocatalysts was established on the homojunction structure, in which Pt acted as the electron collector and was deposited on the bottom, and Co-Pi as the hole-extraction cocatalyst was inserted to accelerate hole transfer on the surface of the photoanode. The resulting Co-Pi/Ca-Fe₂ O₃ /Fe₂ O₃ /Pt branched nanorods showed a significant improvement in charge-separation efficiency and photocurrent density (2.94 mA cm^-2 at 1.23 V vs. RHE). The present strategy, both the construction of the p-n homojunction and the coupling electron- and hole-transfer cocatalyst, could be expanded to many unstable or low-efficiency semiconductors for the design and fabrication of cost-effective photoanodes in PEC water splitting.

Unraveling the Interfacial Charge Migration Pathway at the Atomic Level in a Highly Efficient Z-Scheme Photocatalyst

A highly efficient Z-scheme photocatalytic system constructed with 1D CdS and 2D CoS₂ exhibited high photocatalytic hydrogen-evolution activity of 5.54 mmol h^-1  g^-1 with an apparent quantum efficiency of 10.2 % at 420 nm. More importantly, its interfacial charge migration pathway was unraveled: The electrons are efficiently transferred from CdS to CoS₂ through a transition atomic layer connected by Co-S_5.8 coordination, thus resulting in more photogenerated carriers participating in surface reactions. Furthermore, the charge-trapping and charge-transfer processes were investigated by transient absorption spectroscopy, which gave an estimated charge-separation yield of approximately 91.5 % and a charge-separated-state lifetime of approximately (5.2±0.5) ns in CdS/CoS₂ . This study elucidates the key role of interfacial atomic layers in heterojunctions and will facilitate the development of more efficient Z-scheme photocatalytic systems.

Co3 O4 @Cu-Based Conductive Metal-Organic Framework Core-Shell Nanowire Electrocatalysts Enable Efficient Low-Overall-Potential Water Splitting

In the work reported herein, the electrocatalytic properties of Co₃ O₄ in hydrogen and oxygen evolution reactions have been significantly enhanced by coating a shell layer of a copper-based metal-organic framework on Co₃ O₄ porous nanowire arrays and using the products as high-performance bifunctional electrocatalysts for overall water splitting. The coating of the copper-based metal-organic framework resulted in the hybridization of the copper-embedded protective carbon shell layer with Co₃ O₄ to create a strong Cu-O-Co bonding interaction for efficient hydrogen adsorption. The hybridization also led to electronically induced oxygen defects and nitrogen doping to effectively enhance the electrical conductivity of Co₃ O₄ . The optimal as-prepared core-shell hybrid material displayed excellent overall-water-splitting catalytic activity that required overall voltages of 1.45 and 1.57 V to reach onset and a current density of 10 mA cm^-2 , respectively. This is the first report to highlight the relevance of hybridizing MOF-based co-catalysts to boost the electrocatalytic performance of nonprecious transition-metal oxides.

Interaction-Dependent Interfacial Charge-Transfer Behavior in Solar Water-Splitting Systems

Dual-band-gap systems are promising for solar water splitting due to their excellent light-harvesting capability and high charge-separation efficiency. However, a fundamental understanding of interfacial charge-transfer behavior in the dual-band-gap configuration is still incomplete. Taking CdS/reduced graphene oxide (CdS/RGO) nanoheterojunctions as a model solar water splitting system, we attempt here to highlight the interaction-dependent interfacial charge-transfer behavior based on both experimental observations and theoretical calculations. Experimental evidence points to charge transfer at the CdS-RGO interface playing a dominant role in the photocatalytic hydrogen production activity. By tuning the degree of reduction of RGO, the interfacial interaction, and, thereby, the charge transfer can be controlled at the CdS-RGO interface. This observation is supported by theoretical analysis, where we find that the interfacial charge transfer is a balance between the effective single-electron- and hole-transfer probability and the surface free electron and hole concentration, both of which are related to the surface potential and tailored by interfacial interaction. This mechanism is applicable to all systems for solar water splitting, providing a useful guidance for the design and study of heterointerfaces for high-efficiency energy conversion.

Recent advances in metal sulfides: from controlled fabrication to electrocatalytic, photocatalytic and photoelectrochemical water splitting and beyond

This review describes an in-depth overview and knowledge on the variety of synthetic strategies for forming metal sulfides and their potential use to achieve effective hydrogen generation and beyond.

Three-Dimensional Core-Shell Nanorod Arrays for Efficient Visible-Light Photocatalytic H2 Production

Constructing heterostructured nanomaterials with integrating different functional materials into well-oriented nanoarchitectures is an efficacious tactic to obtain high-performance photocatalysts. In this paper, we fabricated three-dimensional ZnO-WS₂@CdS core-shell nanorod arrays as visible-light-driven photocatalysts for efficient photocatalytic H₂ production. This unique core-shell heterostructure extends visible-light absorption and provides more active sites. More importantly, the ZnO-WS₂@CdS nanorod arrays build a beneficial energy level configuration and spatial structure to accelerate the generation, separation, and transfer of the photogenerated electron-hole. On the basis of the synergistic effects, the photocatalytic H₂ rate of optimized ZnO-WS₂@CdS nanorod arrays achieves 15.12 mmol h^-1 g^-1 in visible light irradiation, which is 39, 9, and 8 times higher than pure CdS, ZnO-CdS, and CdS-WS₂ photocatalysts. The apparent quantum yield is up to 14.92% at 420 nm. Moreover, the core-shell heterostructure photocatalyst can recycle and maintain stability.

Ultrasonic-Assisted Synthesis of 2D α-Fe2O3@g-C3N4 Composite with Excellent Visible Light Photocatalytic Activity

In this study, α-Fe2O3@g-C3N4 photocatalyst was synthesized using an ultrasonic assisted self-assembly preparation method. The α-Fe2O3@g-C3N4 photocatalyst had a stronger optical absorption in the visible light region than pure graphitic carbon nitride (g-C3N4). The Z-Scheme heterojunction between α-Fe2O3 and g-C3N4 significantly inhibited the recombination of electrons and holes. The photocatalytic performances of α-Fe2O3@g-C3N4 photocatalyst were excellent in degradation of Rhodamine B (RhB) under visible light irradiation. The results indicated that 5 wt.% α-Fe2O3/g-C3N4 had the optimal photocatalytic activity because two-dimension (2D) α-Fe2O3 nanosheets can be well-dispersed on the surface of g-C3N4 layers by ultrasonic assisted treatment. A possible photocatalytic mechanism is also discussed.

Group-IVA element-doped SrIn2O4 as potential materials for hydrogen production from water splitting with solar energy

Band gap engineering can efficiently improve the photocatalytic activity of semiconductors for hydrogen generation from water splitting. Herein, we present a comprehensive investigation on the geometrical structures, electronic, optical, and potential photocatalytic properties and charge carrier mobility of pristine and group-IVA element-doped SrIn2O4 using first-principles density functional theory with the meta-GGA+MBJ potential. The calculated formation energies are moderate, indicating that the synthesis of the doped structures is experimentally feasible. In addition, the energy band gaps of the group-IVA element-doped SrIn2O4 range from 1.67 to 3.07 eV, which satisfy the requirements for photocatalytic water splitting, except for that of the Si mono-doped structure. Based on the deformation potential theory, a high charge carrier mobility of 2093 cm2 V-1 s-1 is obtained for the pristine SrIn2O4 and those of the doped-structures are also large, although a decrease in the values of some are observed. The optical absorption coefficient of the doped structures in the near ultraviolet (UV) and visible light range significantly increases. Therefore, group-IVA element-doped SrIn2O4 are potential candidates as photocatalysts for hydrogen generation from water splitting driven by visible light.

Designing CdS Mesoporous Networks on Co-C@Co9 S8 Double-Shelled Nanocages as Redox-Mediator-Free Z-Scheme Photocatalyst

Designing porous nanostructures with unprecedented functionalities and an effective ability to harvest the maximum energy region of the solar spectrum and suppress the charge-carrier recombination rate offers promising potential for sustainable energy production. Although several functional porous nanostructures have been developed, high-efficiency materials are still needed. Herein, we report a new, highly active, noble-metal-free, and redox-mediator-free Z-scheme photocatalyst, CdS/Co-C@Co₉ S₈ , for H₂ production through water splitting under solar irradiation. The designed photocatalytic system contains open 3 D CdS mesopores as a light absorber for wider solar-light harvesting. Metal-organicframework-derived cobalt nanocrystal-embedded few-layered carbon@Co₉ S₈ double-shelled nanocages were used as a co-semiconductor to hamper the photo charge-carrier recombination by accelerating the photogenerated electrons and holes from the other semiconductor. The optimized catalyst shows a H₂ evolution rate of 26.69 mmol g^-1  h^-1 under simulated solar irradiation, which is 46 times higher than that of the as-synthesized CdS mesoporous nanostructures. The apparent quantum yield reached 7.82 % at λ=425 nm in 5 h. The outstanding photocatalytic activity of CdS/Co-C@Co9S8 reflects the favorable suppression of the charge-carrier recombination rate, as determined by photoluminescence, photocurrent, and impedance analyses. We believe that the findings reported here may inspire the design of new noble-metal-free porous nanohybrids for sustainable H₂ production.

Recent advances in three-dimensional graphene based materials for catalysis applications

This review presents recent theoretical and experimental progress in the construction, properties, and catalytic applications of 3D graphene-based materials.

Prussian blue-derived synthesis of uniform nanoflakes-assembled NiS2 hierarchical microspheres as highly efficient electrocatalysts in dye-sensitized solar cells

It's urgent and challenging to explore cost-effective and robust electrocatalyst in the development of large-scaled dye-sensitized solar cells (DSSCs). In this work, we develop a novel strategy to prepare 3D hierarchical NiS₂ microspheres constructed by nanoflakes through a facile chemical etching/anion exchange reaction. Nickel–cobalt Prussian blue analogous (PBA) nanocubes and (NH₄)₂S are employed to initially produce uniform γ-NiOOH/NiS_x hierarchical microspheres, which were then converted to uniform 3D hierarchical NiS₂ microspheres by a controlled annealing treatment. Due to their favorable structural features, the as-obtained NiS₂ hierarchical microspheres possess large surface areas, high structural void porosity and accessible inner surface. All of these advantages facilitate the mass diffusion and charge transport between electrolyte and counter electrode material. As a result, the titled NiS₂ hierarchical microspheres exhibit excellent electrocatalytic activity toward the reduction of I₃⁻ ions in DSSCs. A typical DSSC with NiS₂ achieves an impressive power conversion efficiency of 8.46% under AM1.5G illumination (100 mW cm⁻²), higher than that of pyrolysis Pt electrodes (8.04%). Moreover, the fast activity onset and relatively long stability further demonstrate that the NiS₂ hierarchical microspheres are promising alternatives to Pt in DSSCs.

Hierarchical NiS₂ microspheres constructed by nanoflakes were synthesized by sulfuration of nickel–cobalt Prussian blue analogous nanocubes and they exhibited excellent catalytic activity for the reduction of I₃⁻ ions in dye-sensitized solar cells.

A visible-light driven novel layered perovskite oxyhalide Bi4MO8X (M = Nb, Ta; X = Cl, Br) constructed using BiOX (X = Cl, Br) for enhanced photocatalytic hydrogen evolution

A novel visible-light responsive layered perovskite photocatalyst Bi₄MO₈X (M = Nb, Ta; X = Cl, Br) has been successfully constructed using BiOX (X = Cl, Br) via a solid state method.

Light driven epoxidation of olefins using a graphene oxide/g-C3N4 supported Mo (salen) complex

A novel Schiff (Mo) base complex supported on GO/g-C₃N₄ was prepared and applied to the photocatalytic epoxidation reactions.

0D/2D Z-Scheme Heterojunctions of Bismuth Tantalate Quantum Dots/Ultrathin g-C3N4 Nanosheets for Highly Efficient Visible Light Photocatalytic Degradation of Antibiotics

Constructing 0D/2D Z-scheme photocatalysts is a great promising path to improve photocatalytic activity by  efficiently enhancing charge separation. Herein, we fabricated a visible-light-responsive Bi₃TaO₇ quantum dots (QDs)/g-C₃N₄ nanosheets (NSs) 0D/2D Z-scheme composite via a facile ultrasound method, and Bi₃TaO₇ QDs could be interspersed on the surface of g-C₃N₄ NSs uniformly. Furthermore, the strong interaction between Bi₃TaO₇ QDs and g-C₃N₄ NSs disturbed the CN heterocycles by forming C═O bonds between C atoms of the N-(C)₃ group and O atoms of the Ta-O bond. The optimum composite with 20 wt % g-C₃N₄ NSs showed the superior photocatalytic activity for degradation of ciprofloxacin (CIP) over the composites prepared by mechanical mixing and solid-state methods, the photocatalytic efficiency of which were 4 and 12.2 times higher than those of bare Bi₃TaO₇ and g-C₃N₄. Photoluminescence (PL), time-resolved transient PL decay spectra, and photocurrent together verify that the photogenerated hole-electron pairs in this 0D/2D Z-scheme composite have been effectively separated. The enhanced photocatalytic activity of as-synthesized photocatalysts could be attributed to the synergistic effect of efficient Z-scheme charge separation, highly dispersed 0D Bi₃TaO₇ nanocrystals, coordinating sites of 2D g-C₃N₄ NSs and the strong coupling between them. This study might pave the way toward designing novel visible-light-induced 0D/2D photocatalyst systems for highly efficient degradation of antibiotics.

Metal Phosphides as Co-Catalysts for Photocatalytic and Photoelectrocatalytic Water Splitting

Solar-to-hydrogen conversion based on photocatalytic and photoelectrocatalytic water splitting is considered as a promising technology for sustainable hydrogen production. Developing earth-abundant H₂ -production materials with robust activity and stability has become the mainstream in this field. Due to the unique properties and characteristics, transition metal phosphides (TMPs) have been proven to be high performance co-catalysts to replace some of the classic precious metal materials in photocatalytic water splitting. In this Minireview, we summarize the recent significant progress of TMPs as cocatalysts for water splitting reaction with high activity and stability. Firstly, the characteristic of TMPs is briefly introduced. Then, we mainly discuss the recent research efforts toward their application as photocatalytic co-catalysts in photocatalytic H₂ -production, O₂ -evolution and photoelectrochemical water splitting. Finally, the catalytic mechanism, current existing challenges and future working directions for improving the performance of TMPs are proposed.