Spatially Separating Redox Centers on Z‐Scheme ZnIn2S4/BiVO4 Hierarchical Heterostructure for Highly Efficient Photocatalytic Hydrogen Evolution

Photocatalysis technology using solar energy for hydrogen (H₂) production still faces great challenges to design and synthesize highly efficient photocatalysts, which should realize the precise regulation of reactive sites, rapid migration of photoinduced carriers and strong visible light harvest. Here, a facile hierarchical Z‐scheme system with ZnIn₂S₄/BiVO₄ heterojunction is proposed, which can precisely regulate redox centers at the ZnIn₂S₄/BiVO₄ hetero‐interface by accelerating the separation and migration of photoinduced charges, and then enhance the oxidation and reduction ability of holes and electrons, respectively. Therefore, the ZnIn₂S₄/BiVO₄ heterojunction exhibits excellent photocatalytic performance with a much higher H₂‐evolution rate of 5.944 mmol g^?1 h^?1, which is about five times higher than that of pure ZnIn₂S₄. Moreover, this heterojunction shows good stability and recycle ability, providing a promising photocatalyst for efficient H₂ production and a new strategy for the manufacture of remarkable photocatalytic materials.     

石墨烯-ZnIn2S4纳米复合微球的制备及光催化产氢活性

采用光催化还原法制备了石墨烯-ZnIn₂S₄纳米复合微球。采用XRD、SEM、TEM、FT-IR、XPS和DRS等手段对样品进行表征, 结果表明, 经过光催化还原处理后氧化石墨被还原成石墨烯, ZnIn₂S₄纳米微球负载在石墨烯表面。光催化产氢的实验结果表明, 当石墨烯含量为2.0wt%、光催化还原时间为24 h时, 石墨烯-ZnIn₂S₄纳米复合微球在模拟太阳光下产氢量达到1540.8 μmol, 是纯ZnIn₂S₄纳米微球的9.8倍。增强光催化性能的原因归结为石墨烯在复合光催化剂中起到了电子快速传输作用, 同时还对纳米复合微球光催化产氢反应机理进行了分析讨论。     

In Situ Formation ZnIn2S4/Mo2TiC2 Schottky Junction for Accelerating Photocatalytic Hydrogen Evolution Kinetics: Manipulation of Local Coordination and Electronic Structure

Regulating electronic structures of the active site by manipulating the local coordination is one of the advantageous means to improve photocatalytic hydrogen evolution (PHE) kinetics. Herein, the ZnIn₂S₄/Mo₂TiC₂ Schottky junctions are designed to be constructed through the interfacial local coordination of In³⁺ with the electronegative  O terminal group on Mo₂TiC₂ based on the different work functions. Kelvin probe force microscopy and charge density difference reveal that an electronic unidirectional transport channel across the Schottky interface from ZnIn₂S₄ to Mo₂TiC₂ is established by the formed local nucleophilic/electrophilic region. The increased local electron density of Mo₂TiC₂ inhibits the backflow of electrons, boosts the charge transfer and separation, and optimizes the hydrogen adsorption energy. Therefore, the ZnIn₂S₄/Mo₂TiC₂ photocatalyst exhibits a superior PHE rate of 3.12 mmol g⁻¹ h⁻¹ under visible light, reaching 3.03 times that of the pristine ZnIn₂S₄. This work provides some insights and inspiration for preparing MXene-based Schottky catalysts to accelerate PHE kinetics.     

具有近红外吸收的二维/三维ZnIn2S4/氮掺杂石墨烯光催化剂的制备及其高效CO2捕获和光催化还原性能（英文）

具有宽光谱太阳能利用的分等级异质结光催化剂,正成为一种新兴的先进光催化材料,被应用于太阳能驱动二氧化碳转化为高附加值的化学原料.本工作通过水热法使二维硫化铟锌纳米墙垂直生长于三维氮掺杂石墨烯泡沫上,形成分等级异质结光催化剂.该催化剂展现出优异的光热转换效率、选择性捕获CO2和光催化还原CO2的能力.在273 K和1个大气压条件下,负载1 wt%氮掺杂石墨烯泡沫的复合催化剂表现出最优异的性能,其中对CO2和N2的吸附选择性为30.1,并且对CO2的等量吸附热为48.2 kJ mol^-1.在无助催化剂和牺牲剂的条件下,负载1 wt%氮掺杂石墨烯泡沫的复合催化剂,其光催化转化CO2为CH4、CO和CH3OH的效率分别是纯的硫化铟锌的9.1、3.5和5.9倍.该增强效应得益于三维石墨烯泡沫高度开放的网状结构,良好的CO2吸附能力和两种组份之间的强相互作用.此外,利用原位照射X射线光电子能谱仪和开尔文探针技术分析了电荷转移的方向,本工作为设计高效太阳能转化分等级异质结光催化剂开辟了新的思路.     

Supporting Ultrathin ZnIn2S4 Nanosheets on Co/N‐Doped Graphitic Carbon Nanocages for Efficient Photocatalytic H2 Generation

Ultrathin ZnIn₂S₄ nanosheets (NSs) are grown on Co/N‐doped graphitic carbon (NGC) nanocages, composed of Co nanoparticles surrounded by few‐layered NGC, to obtain hierarchical Co/NGC@ZnIn₂S₄ hollow heterostructures for photocatalytic H₂ generation with visible light. The photoredox functions of discrete Co, conductive NGC, and ZnIn₂S₄ NSs are precisely combined into hierarchical composite cages possessing strongly hybridized shell and ultrathin layered substructures. Such structural and compositional virtues can expedite charge separation and mobility, offer large surface area and abundant reactive sites for water photosplitting. The Co/NGC@ZnIn₂S₄ photocatalyst exhibits outstanding H₂ evolution activity (e.g., 11270 µmol h^?1 g^?1) and high stability without engaging any cocatalyst.     

Tailoring Advanced N-Defective and S-Doped g-C3N4 for Photocatalytic H2 Evolution

Although challenges remain, synergistic adjusting various microstructures and photo/electrochemical parameters of graphitic carbon nitride (g-C₃N₄) in photocatalytic hydrogen evolution reaction (HER) are the keys to alleviating the energy crisis and environmental pollution. In this work, a novel nitrogen-defective and sulfur-doped g-C₃N₄ (S-g-C₃N₄-D) is designed elaborately. Subsequent physical and chemical characterization proved that the developed S-g-C₃N₄-D not only displays well-defined 2D lamellar morphology with a large porosity and a high specific surface area but also has an efficient light utilization and carriers-separation and transfer. Moreover, the calculated optimal Gibbs free energy of adsorbed hydrogen (ΔG_H*) for S-g-C₃N₄-D at the S active sites is close to zero (≈0.24 eV) on the basis of first-principle density functional theory (DFT). Accordingly, the developed S-g-C₃N₄-D catalyst shows a high H₂ evolution rate of 5651.5 µmol g⁻¹ h⁻¹. Both DFT calculations and experimental results reveal that a memorable defective g-C₃N₄/S-doped g-C₃N₄ step-scheme heterojunction is constructed between S-doped domains and N-defective domains in the structural configuration of S-g-C₃N₄-D. This work exhibits a significant guidance for the design and fabrication of high-efficiency photocatalysts.     

Delocalized Spin States in 2D Atomic Layers Realizing Enhanced Electrocatalytic Oxygen Evolution

The electrocatalytic activity of transition‐metal‐based compounds is strongly related to the spin states of metal atoms. However, the ways for regulation of spin states of catalysts are still limited, and the underlying relationship between the spin states and catalytic activities remains unclear. Herein, for the first time, by taking Ni^II‐based compounds without high or low spin states for example, it is shown that their spin states can be delocalized after introducing structural distortion to the atomic layers. The delocalized spin states for Ni atoms can provide not only high electrical conductivity but also low adsorption energy between the active sites and reaction intermediates for the system. As expected, the ultrathin nanosheets of nickel‐chalcogenides with structural distortions show dramatically enhanced activity in electrocatalytic oxygen evolution compared to their corresponding bulk samples. This work establishes new way for the design of advanced electrocatalysts in transition‐metal‐based compounds via regulation of spin states.     

Novel Z-Scheme ZnIn2S4-based photocatalysts for solar-driven environmental and energy applications:Progress and perspectives

Benefiting from strong redox ability,improved charge transport,and enhanced charge separation,Z-scheme heterostructures of ZnIn2S4 based photocatalysts have received considerable interest to tackle energy needs and environmental issues.The present review highlights the properties of ZnIn2S4 which make it a promising photocatalyst,and a suitable combination with oxidation photocatalyst to form Z-scheme,leading to improve their photocatalytic properties dramatically.As the central part of this review,various types of Z-scheme heterojunction developed recently based on ZnIn2S4 and their application in pollutant degradation,water splitting,CO2 reduction,and toxic metals remediation.Some analytical techniques to detect or trap the active radical and study the charge separation and lifetime of charge carriers in these Z-schemes are highlighted.This review offers its readers a broad optical window for the structural architecture of ZnIn2S4-based Z-schemes,photocatalytic activity,stability,and their tech-nological applications.Finally,we discuss the challenges and opportunities for further development on Z-Scheme ZnIn2S4-based photocatalysts toward energy and environmental applications based on the recent progress.     

非贵金属Co5.47N/N-rGO助催化剂增强TiO2光催化制氢性能

高效稳定的光催化剂或助催化剂研究一直是光催化领域的重要课题之一。本研究以氧化石墨烯、氯化钴和2-甲基咪唑为前驱体, 结合液相法和氨气氮化法制备了负载Co_5.47N的氮掺杂还原氧化石墨烯(Co_5.47N/N-rGO), 其中Co_5.47N高度分散、晶粒尺寸为10~20 nm。Co_5.47N/N-rGO可以作为助催化剂有效地改善商业二氧化钛(P25)的光催化分解水制氢性能, 当其质量分数为25%时, 催化剂的制氢性能可以达到11.71 mmol·h ^-1·g ^-1, 相比于纯P25提升了90倍, 与负载贵金属Pt的性能相当(11.88 mmol·h ^-1·g ^-1), 并且具有良好的稳定性。本研究为高效非贵金属助催化剂的研制提供了新思路。     

Atomic Magnetic Heating Effect Enhanced Hydrogen Evolution Reaction of Gd@MoS2 Single-Atom Catalysts

Atomic heating on single atoms (SAs) to maximize the catalytic efficiency of each active site would be a fascinating solution to break the bottleneck for the performance improvement of single-atom catalysts (SACs) but highly challenging task. Here, based on the Gd@MoS₂ SACs synthesized by a facile laser molecular beam epitaxy method, high-frequency alternating magnetic field (AMF) technology is employed to induce atomic magnetic heating on Gd SAs that is meanwhile demonstrated to be the catalytic active center. Significant improvement in catalytic kinetics under AMF excitation (3.9 mT) is achieved, yielding a remarkable enhancement of hydrogen evolution reaction magnetothermal-current by ≈924%. Through theoretical calculations and spin-related electrochemical experiments, such promotion in catalyst activity can be attributed to spin flip (or canting) in Gd SAs leading to the atomic magnetic heating effect on catalytic active center. Together with the embodied high stability, the implement of AMF to the SAs field is demonstrated in this work, and the precisely atomic magnetic heating on specific SAs offers unprecedented thinking for further improvement of SACs performance in the future.     

2D Transition‐Metal‐Dichalcogenide‐Nanosheet‐Based Composites for Photocatalytic and Electrocatalytic Hydrogen Evolution Reactions

Hydrogen (H₂) is one of the most important clean and renewable energy sources for future energy sustainability. Nowadays, photocatalytic and electrocatalytic hydrogen evolution reactions (HERs) from water splitting are considered as two of the most efficient methods to convert sustainable energy to the clean energy carrier, H₂. Catalysts based on transition metal dichalcogenides (TMDs) are recognized as greatly promising substitutes for noble‐metal‐based catalysts for HER. The photocatalytic and electrocatalytic activities of TMD nanosheets for the HER can be further improved after hybridization with many kinds of nanomaterials, such as metals, oxides, sulfides, and carbon materials, through different methods including the in situ reduction method, the hot‐injection method, the heating‐up method, the hydro(solvo)thermal method, chemical vapor deposition (CVD), and thermal annealing. Here, recent progress in photocatalytic and electrocatalytic HERs using 2D TMD‐based composites as catalysts is discussed.     

Self‐Assembled Au/CdSe Nanocrystal Clusters for Plasmon‐Mediated Photocatalytic Hydrogen Evolution

Plasmon‐mediated photocatalytic systems generally suffer from poor efficiency due to weak absorption overlap and thus limited energy transfer between the plasmonic metal and the semiconductor. Herein, a near‐ideal plasmon‐mediated photocatalyst system is developed. Au/CdSe nanocrystal clusters (NCs) are successfully fabricated through a facile emulsion‐based self‐assembly approach, containing Au nanoparticles (NPs) of size 2.8, 4.6, 7.2, or 9.0 nm and CdSe quantum dots (QDs) of size ≈3.3 nm. Under visible‐light irradiation, the Au/CdSe NCs with 7.2 nm Au NPs afford very stable operation and a remarkable H₂‐evolution rate of (10× higher than bare CdSe NCs). Plasmon resonance energy transfer from the Au NPs to the CdSe QDs, which enhances charge‐carrier generation in the semiconductor and suppresses bulk recombination, is responsible for the outstanding photocatalytic performance. The approach used here to fabricate the Au/CdSe NCs is suitable for the construction of other plasmon‐mediated photocatalysts.     

Surface Engineering for Extremely Enhanced Charge Separation and Photocatalytic Hydrogen Evolution on g‐C3N4

Reinforcing the carrier separation is the key issue to maximize the photocatalytic hydrogen evolution (PHE) efficiency of graphitic carbon nitride (g‐C₃N₄). By a surface engineering of gradual doping of graphited carbon rings within g‐C₃N₄, suitable energy band structures and built‐in electric fields are established. Photoinduced electrons and holes are impelled into diverse directions, leading to a 21‐fold improvement in the PHE rate.     

Au NPs@MoS2 Sub‐Micrometer Sphere‐ZnO Nanorod Hybrid Structures for Efficient Photocatalytic Hydrogen Evolution with Excellent Stability

MoS₂ shows promising applications in photocatalytic water splitting, owing to its uniquely optical and electric properties. However, the insufficient light absorption and lack of performance stability are two crucial issues for efficient application of MoS₂ nanomaterials. Here, Au nanoparticles (NPs)@MoS₂ sub‐micrometer sphere‐ZnO nanorod (Au NPs@MoS₂‐ZnO) hybrid photocatalysts have been successfully synthesized by a facile process combining the hydrothermal method and seed‐growth method. Such photocatalysts exhibit high efficiency and excellent stability for hydrogen production via multiple optical‐electrical effects. The introduction of Au NPs to MoS₂ sub‐micrometer spheres forming a core–shell structure demonstrates strong plasmonic absorption enhancement and facilitates exciton separation. The incorporation of ZnO nanorods to the Au NPs@MoS₂ hybrids further extends the light absorption to a broader wavelength region and enhances the exciton dissociation. In addition, mutual contacts between Au NPs (or ZnO nanorods) and the MoS₂ spheres effectively protect the MoS₂ nanosheets from peeling off from the spheres. More importantly, efficiently multiple exciton separations help to restrain the MoS₂ nanomaterials from photocorrosion. As a result, the Au@MoS₂‐ZnO hybrid structures exhibit an excellent hydrogen gas evolution (3737.4 μmol g^?1) with improved stability (91.9% of activity remaining) after a long‐time test (32 h), which is one of the highest photocatalytic activities to date among the MoS₂ based photocatalysts.     

直接Z-型立方/六方ZnIn2S4复合光催化剂的制备及其光催化性能

通过水热反应方法制备出立方相ZnIn₂S₄和六方相ZnIn₂S₄和系列不同摩尔比的复合相ZnIn₂S₄光催化剂,使用X射线衍射、扫描电子显微镜、电子能谱、透射电子显微镜、光致发光光谱、N₂吸附-脱附法及紫外-可见光漫反射等手段表征了样品的晶体结构、显微结构及吸光特性并在可见光照射下进行了甲基橙降解实验。结果表明,复合相ZnIn₂S₄样品都具有比立方相、六方相和机械混合的ZnIn₂S₄更好的可见光催化活性,当复合相ZnIn₂S₄样品中立方相与六方相摩尔比为3:7时体系的催化活性最高。这种样品被可见光照射30 min后,甲基橙的降解率达到95.2%。其降解机理与样品较大的比表面积以及样品中的立方相与六方相之间的密切接触而形成直接Z-型光催化过程有关。     

Spontaneous Dewetting of Au-Thin Layers on Oxide- and Fluorine-Terminated Single Crystalline Anatase and Efficient Use in Photocatalytic H2 Production

In the present work, the spontaneous dewetting of thin Au layers on single crystalline anatase nanosheets into narrow-disperse Au nanoparticles is investigated. Patterns of the Au particles can be formed on the main facets of anatase that provide a high co-catalytic activity for photocatalytic generation of H₂. Dewetting is distinctly influenced by the respective facets (001) and (101), the deposit thickness, and secondary thermal dewetting, but most strongly by the surface termination of the nanosheets. Fluoride termination not only leads to an enhanced Au-phobic behavior but strongly affects the co-catalytic activity for photocatalytic generation of H₂. While fluoride termination with or without Au decoration is detrimental for hole transfer, the interplay of the Au co-catalyst and surface fluoride yields highly beneficial effect for electron transfer. This results in a three-times higher photocatalytic H₂ production for the F-terminated surface. The findings suggest that dewetting of Au on surface fluorinated TiO₂ is an effective way to modulate surface dewetting and achieve a strongly enhanced photocatalytic activity.     

The Precision Defect Engineering with Nonmetallic Element Refilling Strategy in g-C3N4 for Enhanced Photocatalytic Hydrogen Production

Traditional defect engineering and doping strategies are considered effective means for improving H₂ evolution, but the uncontrollability of the modification process does not always lead to efficient activity. A defect-induced heteroatom refilling strategy is used here to synthesize heteroatoms introduced carbon nitride by precisely controlling the “introduction” sites on efficient N1 sites. Density functional theory calculations show that the refilling of B, P, and S sites have stronger H₂O adsorption and dissociation capacity than traditional doping, which makes it an optimal H₂ production path. The large internal electric field strength of heteroatom-refilled catalysts leads to fast electron transfer and the hydrogen production of the best sample is up to 20.9 mmol g⁻¹ h⁻¹. This work provides a reliable and clear insight into controlled defect engineering of photocatalysts and a universal modification strategy for typical heteroatom and co-catalyst systems for H₂ production.     

Zn2GeO4微米球的一步合成及其光催化制氢活性

采用微波辅助水热法一步合成尺寸约为5 μm的Zn₂GeO₄微米球。实验研究了微波水热的反应温度、反应时间、乙酸锌与氧化锗的摩尔比等因素对合成Zn₂GeO₄微米球的影响。采用FE-SEM、TEM、XRD和UV-Vis对合成的微米球进行表征。结果表明, 当乙酸锌：氧化锗为6:2, 微波辐射温度为170℃, 反应时间10 min, 尿素用量3.604 g, 制备的Zn₂GeO₄微米球具有良好的光催化效果。实验测试Zn₂GeO₄微米球比表面积为13 m²/g, 在紫外光辐射下, 在甲醇体系中的光解水产氢速率可达到3.76 mmol/(h·g)。该方法缩短反应时间, 增强了光催化活性。