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A series of twin-phase Mn x Cd 1-x S solid solutions with zinc blende (ZB) and wurtzite (WZ) structures were prepared by an alkaline hydrothermal method in this work. When using 0.35 M Na 2 SO 3 /0.25 M Na 2 S solution as a sacrificial agent under visible light (λ ≥ 420 nm), the H 2 production activity of T-Mn 0.5 Cd 0.5 S is 33.4 mmol h−1 g−1, significantly higher than that of ZB-Mn 0.5 Cd 0.5 S (15.4 mmol h−1 g−1) or WZ-Mn 0.5 Cd 0.5 S (18.2 mmol h−1 g−1). The photocatalytic activity of T-Mn 0.5 Cd 0.5 S is further enhanced by introducing Ni 12 P 5 as a cocatalyst, in which the H 2 evolution rate of 0.2% Ni 12 P 5 /T-Mn 0.5 Cd 0.5 S can reach 96.5 mmol h−1 g−1, 2.89 and 1.77 times than that of pure T-Mn 0.5 Cd 0.5 S and 0.5% Pt/T-Mn 0.5 Cd 0.5 S (54.6 mmol h−1 g−1), respectively. The crystalline phase, microstructure, elemental composition, optical and optoelectronic properties of the samples were characterized by XRD, SEM, TEM, HRTEM, XPS, UV–vis, PL and electrochemical workstation. The results show that the formation of a homojunction with interlaced energy band inhibits carrier recombination in the bulk phase of T-Mn 0.5 Cd 0.5 S. In addition, Ni 12 P 5 can substitute for the noble metal as a cocatalyst to reduce the overpotential and improve the separation rate of electrons and holes to enhance H 2 evolution. This work provides reference for building homojunction photocatalysts and loading inexpensive transition metal phosphides instead of noble metals. [Display omitted] • The twinned Mn x Cd 1-x S of zinc blende (ZB) and wurtzite (WZ) was prepared in an alkaline hydrothermal method. • The introduction of Ni 12 P 5 by in situ hydrothermal method further enhanced photocatalytic H 2 evolution activity. • The efficient Ni 12 P 5 /T-Mn 0.5 Cd 0.5 S photocatalyst is a beneficial effect of twinned structure and cocatalyst Ni 12 P 5. [ABSTRACT FROM AUTHOR]

Halide perovskites are excellent catalysts for photocatalytic hydrogen (H2) evolution; however, their instability in aqueous systems limits their applications. In this study, an alternative system is presented to avoid the ionization of halide perovskites based on ethanol splitting and three Bi‐based halide perovskite nanosheets (Cs3Bi2X9 PNs; X = I, Br, Cl) are prepared for H2 evolution. Small amounts of these halide perovskites possess good stability in ethanol, where the optimal Cs3Bi2I9 PNs exhibit the highest H2 evolution rate of 2157.8 µmol h−1 g−1. In particular, the effects of halogen regulation on the H2 evolution activity are investigated in depth from various perspectives for Cs3Bi2X9. The increased number of halogen atoms reduces the Bi···Bi distance in the octahedral configuration and eliminates the strong localization of electron–hole pairs, which are conducive to photogenerated charge separation and transfer. In addition, the dominant contribution of halogens to the conduction band is enhanced with an increase in the halogen atomic number. This study establishes a novel strategy for studying Bi‐based perovskites for optimizing their photocatalytic properties. Furthermore, it provides a new perspective for developing highly efficient and stable H2 evolution systems for halide perovskites. [ABSTRACT FROM AUTHOR]

Z-Scheme highly dispersed bimetallic CuCo 2 O 4 /g-C 3 N 4 heterojunction was fabricated, which shows much higher activity than that of single metal CuO/g-C 3 N 4 or Co 3 O 4 /g-C 3 N 4 composite. It is found that the faster H 2 evolution kinetics and larger number of surface acidity sites of CuCo 2 O 4 /g-C 3 N 4 are responsible for its good performance in triethanolamine solution. Photocatalytic reaction refers to a sophisticated heterogeneous catalyzing process. Exploring the interfacial reaction of catalysts will provide insights into efficient artificial photosynthetic system and promote its design. In this study, highly dispersed bimetallic CuCo 2 O 4 nanoclusters decorated g-C 3 N 4 heterojunction photocatalyst was produced by in-situ deposition of 0D CuCo 2 O 4 spinel on the 2D g-C 3 N 4 surface. Compared with CuO or Co 3 O 4 modified g-C 3 N 4 , the optimal composite exhibits a significantly higher H 2 evolution rate of 4187.6 μmol∙g cat −1∙h−1 with an apparent quantum yield (AQY) of 4.57% under the irradiation of monochromatic light (400 ± 7.5 nm) in the absence of noble metal. As suggested from the results of the photoelectrochemistry characterizations and NH 3 -temperature programmed desorption (NH 3 -TPD) analysis, CuCo 2 O 4 /g-C 3 N 4 exhibited faster HER kinetics and considerable surface acidity sites, and it facilitated triethanolamine (TEOA) chemisorption and H 2 evolution, further highlighting the merits of such mixed-metal compounds. Moreover, the transfer pathway of charge carriers between CuCo 2 O 4 and g-C 3 N 4 heterogeneous interface was demonstrated by photo-degradation of RhB and selective photo-deposition Pt nanoparticles. [ABSTRACT FROM AUTHOR]

[Display omitted] • An universal cascaded reaction was employed to strength surface reaction of water splitting. • OH act as reaction intermediate that linking OH− and OH scavengers (MeOH). • OH− not only reduce the apparent activation energy but also change the reaction pathway. • Facilitated surface redox endows the system excellent anti-photocorrosion ability and activity. In photocatalysis, researchers mainly focus on the physical processes of light absorption and charge recombination, however, the surface chemical reaction process has been largely overlooked. Herein, a cascaded reaction strategy was employed to strengthen the surface reaction of water splitting over Co decorated ultrathin Cd 0.5 Zn 0.5 S nanosheets (Co/Cd 0.5 Zn 0.5 S), in which OH− from NaOH can be oxidized to OH by the holes of Cd 0.5 Zn 0.5 S, then it can be consumed by OH scavengers. Methanol (MeOH) was employed as a model scavenger to investigate surface redox kinetics of the system. The investigations show that OH− can reduce the apparent activation energy of MeOH photo-reforming by changing its oxidation pathway from a slow direct adsorption-oxidation path to a quick OH-mediated indirect path. The apparent MeOH decomposition kinetic via the direct path fits Langmuir-Hinshelwood model with a rate constant of 0.117 ± 0.007 mmol·h−1 at 30 °C. Whereas it is converted to zero-order reaction with rate constant of 0.734 ± 0.027 mmol·h−1 at 30 °C in the presence of OH−, where MeOH decomposition efficiency largely depends on the OH− adsorption and diffusion processes. The greatly enhanced surface charge extraction by OH− endows Co/Cd 0.5 Zn 0.5 S excellent anti-photocorrosion ability and highest activity of 178.4 ± 5.9 mmol‧g−1‧h−1, making a sustainable photocatalytic H 2 evolution process. This work sheds light on rational design of reaction to achieve efficient photocatalytic H 2 evolution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cd 0.5 Zn 0.5 S nanosheets were employed for H 2 evolution without a hole scavenger. • NaOH boosts hole scavenging and lessens Cd 0.5 Zn 0.5 S photocorrosion. • OH− adsorption is a rate-limiting step in photocatalytic H 2 generation. • The 'photocatalyst-electrolyte' strategy is applicable to other chalcogenides. The surface photocatalytic water splitting kinetics of ultrathin Cd 0.5 Zn 0.5 S nanosheets without hole scavengers is critically examined, focusing on the effects of the pH and NaOH as an electrolyte. In aqueous NaOH, hole scavenging from Cd 0.5 Zn 0.5 S is enhanced, which reduces catalyst photocorrosion. Based on the Langmuir-Hinshelwood model, OH− adsorption on Cd 0.5 Zn 0.5 S is the rate-limiting step of the whole process, and the reaction rate increases with increase in pH and temperature. The hydrogen evolution reaction (HER) activity of Cd 0.5 Zn 0.5 S reaches 12.44 and ∼ 20 mmol‧g−1‧h−1 at 303.15 K and 313.15 K (6 M NaOH, 0.5 h), respectively, two orders of magnitude higher than that in pure water. At high pH, direct OH− oxidation is favored, enhancing water splitting and indicating that water oxidation shifts to a ∙OH production pathway with activation energy approximately of 23.73 kJ‧ mol−1. Promisingly, this strategy to improve H 2 production rates is applicable to other chalcogenide photocatalysts (CdS, Cd 0.5 Mn 0.5 S, ZnSe and Cd 0.5 Zn 0.5 Se). [ABSTRACT FROM AUTHOR]

Herein, Ni 12 P 5 /Cd 0 · 5 Zn 0 · 5 S composites were synthesized through a two-step hydrothermal method to enhance the photocatalytic H 2 production. The results show that 10%-Ni 12 P 5 /Cd 0 · 5 Zn 0 · 5 S composites exhibited the highest H 2 production rate with 46.82 mmol g−1 h−1, which was 5.1 times higher than that of monomer Cd 0 · 5 Zn 0.5 S. The apparent quantum efficiency (AQE) was 24.5% under 400 (±5) -nm light irradiation. The improved activity can be attributed to the enhanced light absorption and promoted separation of photogenerated charge carriers after Ni 12 P 5 was introduced. The structures, morphology and photoelectrochemical properties are investigated in detail. This work provides a convenient and low cost method to develop high-efficiency photocatalyst for environmental and energy-related applications. Image 1 • Ni 12 P 5 was firstly fabricated by using red phosphorus as phosphorus source. • Ni 12 P 5 decorated Cd 0 · 5Zn 0 · 5 S was obtained by an in-situ hydrothermal method. • H 2 production AQE of 10%-Ni 12 P 5 /Cd 0 · 5 Zn 0 · 5 S reaches 24.5% under 400 (±5) nm. • The charge transfer pathway was revealed by hydroxyl radical test using TA as indicator. [ABSTRACT FROM AUTHOR]

The photocatalytic evolution of hydrogen is a potential method for acquiring green hydrogen from nature. Unfortunately, this technique has limitations owing to a lack of knowledge of the reaction processes, despite the fact that in recent decades significant scientific adva'nces have been achieved regarding catalyst design and efficiency. Often neglected in favor of heterojunction engineering or band engineering, the chemical environment of catalysts has long been the subject of research. This article offers insight into the photocatalytic H 2 evolution from the surface reaction. It was underlined that reactant adsorption and surface charge extraction have a significant impact on the enhancement of photocatalytic H 2 evolution and anti-photocorrosion properties of the catalyst, which are also strongly connected to the catalyst's chemical environment. Specifically, this study emphasizes the significance of surface/interface condition, type and concentration of electrolytes, reaction solvents, and temperature, etc., during photocatalytic H 2 development, all of which play a crucial role in surface charge extraction of catalyst. In addition, the surface kinetics, adsorption and diffusion of reactants, the selectivity of intermediates, etc., are emphasized for designing highly efficient reaction systems in future applications of photocatalysis. It was shown that more comprehensive methodologies are urgently required for constructing efficient and stable photocatalytic reaction systems by merging catalyst design and reaction environment manipulation. This review may provide fresh ideas for the use of photocatalytic solar energy conversion. [Display omitted] • Photocatalytic thermodynamics and surface reaction kinetics were briefly summarized. • It was addressed the influence of reaction circumstances on H 2 evolution and apparent kinetics. • Emphasized the importance of an external factor in the research of photocatalytic apparent kinetics. • Discussed the prospect of inhibiting photocorrosion by increasing surface response. [ABSTRACT FROM AUTHOR]

The effectiveness of charge transfer and separation between bulk phase and the interface is crucial for evaluating the performance of photocatalysts. In this study, NiMoO 4 was employed to enhance the photocatalytic activity for hydrogen (H 2) evolution in twinned Cd 0.5 Zn 0.5 S (T-CZS) homojunctions comprising of wurtzite Cd 0.5 Zn 0.5 S (WZ-CZS) and zinc blende Cd 0.5 Zn 0.5 S (ZB-CZS) with alternating arrangements. The investigation reveals that the introduction of NiMoO 4 can lead to an increase of active sites for H 2 evolution, a prolongation of charge carrier lifetime, and a decrease of H 2 evolution overpotential. The H 2 production rate of 8 wt % NiMoO 4 /T-CZS reaches up to 71.2 mmol h−1 g−1, while its apparent quantum efficiency (AQY) is 8.23% at 400 nm. The enhanced activity can be attributed to the synergistic effects of homojunctions and heterojunctions in NiMoO 4 /T-CZS. According to the density functional theory (DFT), photoelectric response, and radical trapping experimental analysis, the charge transfer between WZ-CZS and ZB-CZS in T-CZS, as well as NiMoO 4 and T-CZS, both follow the S-scheme pathway under the influence of band bending, Coulombic force, and built-in electric field. This leads to an effective internal and interfacial charge separation in NiMoO 4 /T-CZS homo-heterojunctions, while maintaining their high reactivity. Additionally, the H 2 evolution activity of T-CZS can also be increased in different degrees by various metal molybdates (MMoO 4) including CoMoO 4 , Ag 2 MoO 4 , Bi 2 (MoO 4) 3 , BaMoO 4 , ZnMoO 4 , and CdMoO 4. The bulk and interfacial synergistic double S-scheme homo-heterojunctions in this study provide new insights for targeted solar driven H 2 evolution engineering. The NiMoO 4 /T-Cd 0.5 Zn 0.5 S system demonstrates a double S-scheme electron transfer pathway, leveraging the synergistic effects of interface S-scheme heterojunctions and bulk S-scheme homojunctions to facilitate efficient charge separation and transfer processes, thereby resulting in exceptional H 2 evolution performance. [Display omitted] • Twinned-Cd 0.5 Zn 0.5 S (T-CZS) consisting of zinc blende Cd 0.5 Zn 0.5 S and wurtzite Cd 0.5 Zn 0.5 S are successfully synthesized. • The photocatalytic H 2 evolution rate of NiMoO 4 /T-CZS with double S-scheme homo-heterojunctions reaches 71.2 mmol h−1 g−1. • MMoO 4 /T-CZS (M = Ni, Co, Ag, Bi, Ba, Zn, Cd) all exhibit excellent H 2 evolution performance. [ABSTRACT FROM AUTHOR]