To solve resource, energy, and environmental issues, development of sustainable clean energy system is strongly required. In recent years, hydrogen has been paid much attention to as a clean energy. Solar hydrogen production by water splitting using a photocatalyst as artificial photosynthesis is a promising method to solve these issues. Efficient utilization of visible light comprised of solar light is essential for practical use. Three strategies, i.e., doping, control of valence band, and formation of solid solution are often utilized as the useful methods to develop visible light responsive photocatalysts. This mini-review introduces the recent work on visible-light-driven photocatalysts developed by substitution with metal cations of those strategies.

光催化剂由于其优异的性能和同时解决能源需求和环境污染方面的挑战的潜力而引起了广泛的研究兴趣。 实际应用中光催化颗粒需要与它们各自的介质接触才能表现出高效的光催化能。 然而，纳米级的光催化材料后期很难从反应介质中分离出来，不可避免的会导致二次污染和比较差得循环行能。 三维网络结构的水凝胶光催化材料具有高比表面积、高吸附能力和良好的环境相容性等特点，是一种很有前途的光催化剂载体材料。 本文根据水凝胶光催化材料的组成将其分为两类，并对近年来水凝胶光催化材料的制备方法进行了总结。 此外，综述了目前水凝胶光催化材料在能源转化和环境修复中的应用。 并对水凝胶光催化材料所遇到的挑战和发展前景进行了简要阐述。

Photoelectrochemical (PEC) water splitting is regarded as a promising way for solar hydrogen production, while the fast development of photovoltaic-electrolysis (PV-EC) has pushed PEC research into an embarrassed situation. In this paper, a comparison of PEC and PV-EC in terms of efficiency, cost, and stability is conducted and briefly discussed. It is suggested that the PEC should target on high solar-to-hydrogen efficiency based on cheap semiconductors in order to maintain its role in the technological race of sustainable hydrogen production.

Converting solar energy into hydrogen (H₂) by photocatalytic water splitting is a promising approach to simultaneously address the increasing energy demand and environmental issues. Half decade has passed since the discovery of photo-induced water splitting phenomenon on TiO₂ photoanode, while the solar to H₂ efficiency is still around 1%, far below the least industrial requirement. Therefore, developing efficient photocatalyst with a high energy conversion efficiency is still one of the main tasks to be overcome. Graphitic carbon nitride (g-C₃N₄) is just such an emerging and potential semiconductor. Therefore, in this review, the state-of-the-art advances in g-C₃N₄ based photocatalysts for overall water splitting were summarized in three sections according to the strategies used, and future challenges and new directions were discussed.

基于光催化剂的光解水制氢是生产可再生能源的重要研究方向。其中尖晶石铁氧体是一种具有应用潜力的光催化剂（相对窄的带隙、可调节的能带位置、化学和热稳定性、磁性能）。窄带隙保证了更广泛的可见光吸收强度，适当的能级位置可以增强对水的还原或者氧化能力，磁性能促进了催化剂回收的便捷性。然而，光激发电子和空穴的快速复合抑制了铁氧体的催化性能。因此，本文总结了近期铁氧体基于结晶度、颗粒尺寸、比表面积、形貌和能带结构的优化调控策略。此外，也总结了铁氧体在与TiO₂或g-C₃N₄复合状态下的作用。除了异质结引起的电子空穴分离增强作用，铁氧体中的过渡金属也可以诱导TiO2中产生掺杂或者缺陷能级，从而增强光吸收和电子空穴分离能力。强氧化活性的铁氧体也可以增强g-C₃N₄/铁氧体复合体系的氧化反应动力速率，从而保证电子的还原效率。最后两组复合体系CaFe₂O₄/MgFe₂O₄和ZnFe₂O₄/CdS分别探究了高效异质结的构建策略和抗光腐蚀的能力。

Uses of layered alkali titanates (A₂Ti_nO_2n+1; Na₂Ti₃O₇, K₂Ti₄O₉, and Cs₂Ti₅O₁₁) for energy and environmental issues are summarized. Layered alkali titanates of various structural types and compositions are regarded as a class of nanostructured materials based on titanium oxide frameworks. If compared with commonly known titanium dioxides (anatase and rutile), materials design based on layered alkali titanates is quite versatile due to the unique structure (nanosheet) and morphological characters (anisotropic particle shape). Recent development of various synthetic methods (solid-state reaction, flux method, and hydrothermal reaction) for controlling the particle shape and size of layered alkali titanates are discussed. The ion exchange ability of layered alkali titanate is used for the collection of metal ions from water as well as a way of their functionalization. These possible materials design made layered alkali titanates promising for energy (including catalysis, photocatalysts, and battery) and environmental (metal ion concentration from aqueous environments) applications.

近年来，缺陷型UiO-66(Zr)系列MOFs材料因具有超大的比表面积、良好的孔结构和灵活可变的可调控性在催化、功能材料和吸附等领域展示出巨大的应用前景。在合成MOFs时引入缺陷位点用于调控材料的物理化学性质如（能带结构、孔结构等）获得优异的性能是极其具有挑战性的。本文结合近几年的研究成果，综述了缺陷型UiO-66(Zr)系列MOFs材料合成方法、表征技术和应用领域等，以期提供一些合成高性能UiO-66(Zr)系列MOFs材料的思路，促进UiO-66(Zr)系列MOFs材料在各个领域的发展。

Owing to the outstanding characteristics of tailorable electronic and optical properties, semiconducting polymers have attracted considerable attention in recent years. Among them, organic polymer dots process large breadth of potential synthetic diversity are the representative of photocatalysts for hydrogen production, which presents both an opportunity and a challenge. In this mini-review, first, the organic polymer photocatalysts were introduced. Then, recent reports on polymer dots which showed a superior photocatalytic activity and a robust stability under visible-light irradiation, for hydrogen production were summarized. Finally, challenges and outlook on using organic polymer dots-based photocatalysts from hydrogen production were discussed.

光催化水分解制氢（H₂）是解决能源危机和环境恶化问题的一种潜在策略。然而，粉末状光催化剂难以回收利用，同时，颗粒的团聚也会对光催化活性产生影响。本文基于碳布通过两步法制备了CdS/WO₃ Z型复合光催化剂。在碳布的支撑下，光催化剂趋于均匀生长，有利于进一步应用。实验结果表明，加入一片CdS/WO3复合材料情况下的H2产率为17.28 μmol·h^-1，是单负载CdS碳布材料的5.5倍。制备材料的稳定性用循环实验进行了验证，结果表明负载有CdS/WO₃碳布样品的 H₂ 生成性能在 3 次循环后仅略有下降。这项工作为可回收光催化剂的开发提供了新思路，对实际应用具有积极意义。

本文首先在混合物流动模型的基础上建立了优化的六通量辐射模型，同时分析了催化剂浓度和循环速度等参数对反应器出口光催化剂分布和辐射分布的影响。将优化后的六通量模型应用于管式太阳能光催化反应器进行性能评价，模拟结果表明，当催化剂浓度越高，液相入口流速越慢时，管式光催化反应器具有更好的辐射性能。(3倍催化剂浓度，1/3循环速度工况下，能量数值相对分别增加了1900%和284%)。

本文通过在氮气氛围中利用硼氢化钠热处理钛酸锶纳米晶合成了表面重建的钛酸锶纳米晶。 钛酸锶纳米晶的表面重建源于在氢化处理过程中引入了表面氧空位或Ti位点（如Ti³⁺和Ti²⁺）。由于表面氧空位或Ti位点（如Ti³⁺和Ti²⁺）存在，使得钛酸锶纳米晶的光吸收和电荷转移能力同时得以提高，这有力地增强了其光催化分解水性能。同时，这些缺陷也改变了钛酸锶的氧化还原电势。在这三者之间协同作用下，钛酸锶分解纯水时，氢气与氧气的产生比例也得到了调节。

InP shows a very high efficiency for solar light to electricity conversion in solar cell and may present an expectation property in photocatalytic hydrogen evolution. However, it suffers serious corrosion in water dispersion. In this paper, it is demonstrated that the stability and activity of the InP-based catalyst are effectively enhanced by applying an anti-corrosion SnO layer and In(OH)₃ transition layer, which reduces the crystal mismatch between SnO and InP and increases charge transfer. The obtained Pt/SnO/In(OH)₃/InP exhibits a hydrogen production rate of 144.42 µmol/g in 3 h under visible light illumination in multi-cycle tests without remarkable decay, 123 times higher than that of naked In(OH)₃/InP without any electron donor under visible irradiation.

以水热法合成的TiO₂和三聚氰胺（MA）为原料，采用原位氮化法制备了氮化钛（TiN）修饰的N-掺杂二氧化钛（N-TiO₂）复合材料（TiN/N-TiO₂）。通过优化反应条件，得到的TiN/N-TiO₂复合材料在氙灯全光谱照射下的析氢活性高达703μmol h^-1，分别是单纯的TiO₂和TiN的2.6倍和32.0倍。为了探索其光催化反应机理，对复合材料的晶相、形貌、光吸收性能、能带结构、元素组成和电化学行为进行了表征和分析。结果表明，TiN/N-TiO₂复合材料光催化活性的提高主要是由于在原位生产的TiN和N-TiO₂界面形成了紧密的接触，这不仅扩展了复合材料的光谱响应范围，而且可加速TiN光激发热载流子的转移和分离。本研究为原位制备具有高效分解水产氢活性的非金属等离子体材料/N-掺杂TiO₂复合光催化材料提供了一条新的途径。

In this study, the electronic and photocatalytic properties of core-shell heterojunctions photocatalysts with reversible configuration of TiO₂ and Bi₂O₃ layers were studied. The core-shell nanostructure, obtained by efficient control of the sol-gel polymerization and impregnation method of variable precursors of semiconductors, makes it possible to study selectively the role of the interfacial charge transfer in each configuration. The morphological, optical, and chemical composition of the core-shell nanostructures were characterized by high-resolution transmission electron microscopy, UV-visible spectroscopy and X-ray photoelectron spectroscopy. The results show the formation of homogenous TiO₂ anatase and Bi₂O₃ layers with a thickness of around 10 and 8 nm, respectively. The interfacial charge carrier dynamic was tracked using time resolved microwave conductivity and transition photocurrent density. The charge transfer, their density, and lifetime were found to rely on the layout layers in the core-shell nanostructure. In optimal core-shell design, Bi₂O₃ collects holes from TiO₂, leaving electrons free to react and increase by 5 times the photocatalytic efficiency toward H₂ generation. This study provides new insight into the importance of the design and elaboration of optimal heterojunction based on the photocatalyst system to improve the photocatalytic activity.

本论文提出了制备一种新型的BiOI/WO3纳米片阵列(NFA)光阳极并光电催化(PEC)处理有毒H2S并回收到H2和S的方法。通过将BiI3浸渍羟基化后，再通过钨酸盐的转化，在导电衬底上均匀地制备出了垂直排列的BiOI/WO3纳米片电极(BiOI/WO3 NFA)。与纯WO3 NFA相比，BiOI/WO3 NFA的光电流显著提高了200%。由于BiOI/WO3-NFA光阳极和I−/ 催化体系具有良好的稳定性和光活性，在太阳光照射下，催化分解H2S的PEC体系可以将S2−完全转化为S，而不存在任何多硫化物( )，同时生成H2的速率约为0.867 mL/(h·cm2)。本论文提出的PEC 分解H2S的方法为回收H2和S提供了一条有效的途径。

以硫粉为硫源，固相法原位生长超薄MoS₂于CdS纳米棒表面并进行光催化产氢研究。表征结果显示少层（单层或两层）MoS₂担载在CdS纳米棒表面且二者具有良好的界面接触。光电化学测试结果表明MoS₂不仅有利于光生电荷的分离同时为活性位从而提高光催化制氢活性。负载的MoS₂可以显著提升CdS的光催化活性。质量比为MoS₂：CdS = 1：50 时，催化剂的产氢速率达到542 μmol/h, 为未负载CdS的6倍。该研究不仅为设计高活性的光催化材料提供思路而且加深理解MoS₂提升光催化活性的作用。

The serious surface charge recombination and fatigued photogenerated carriers transfer of the BiVO₄ photoanode restrict its photoelectrochemical (PEC) water splitting performance. In this work, nickel fluoride (NiF₂) is applied to revamp pure BiVO₄ photoanode by using a facile electrodeposition method. As a result, the as-prepared NiF₂/BiVO₄ photoanode increases the dramatic photocurrent density by approximately 180% compared with the pristine BiVO₄ photoanode. Furthermore, the correlative photon-to-current conversion efficiency, the charge injection, and the separation efficiency, as well as the hydrogen generation of the composite photoanode have been memorably enhanced due to the synergy of NiF₂ and BiVO₄. This study may furnish a dependable guidance in fabricating the fluoride-based compound/semiconductor composite photoanode system.

MoS₂ is a promising electrocatalyst for hydrogen evolution reaction and a good candidate for cocatalyst to enhance the photoelectrochemical (PEC) performance of Si-based photoelectrode in aqueous electrolytes. The main challenge lies in the optimization of the microstructure of MoS₂, to improve its catalytic activity and to construct a mechanically and chemically stable cocatalyst/Si photocathode. In this paper, a highly-ordered mesoporous MoS₂ was synthesized and decorated onto a TiO₂ protected p-silicon substrate. An additional TiO₂ necking was introduced to strengthen the bonding between the MoS₂ particles and the TiO₂ layer. This meso-MoS₂/TiO₂/p-Si hybrid photocathode exhibited significantly enhanced PEC performance, where an onset potential of +0.06 V (versus RHE) and a current density of −1.8 mA/cm² at 0 V (versus RHE) with a Faradaic efficiency close to 100% was achieved in 0.5 mol/L H₂SO₄. Additionally, this meso-MoS₂/TiO₂/p-Si photocathode showed an excellent PEC ability and durability in alkaline media. This paper provides a promising strategy to enhance and protect the photocathode through high-performance surface cocatalysts.

In this paper, the fabrication of a highly orientated Bi₂Fe₄O₉ (BFO) photoelectrode in the presence of two-dimensional (2D) graphene oxide (GO) was reported. It was found that the GO can be used as a template for controlling the growth of BFO, and the nanoplate composites of BFO/reduced graphene oxide (RGO) with a high orientation can be fabricated. The thickness of the nanoplates became thinner as the ratio of GO increased. As a result, the ferroelectric spontaneous polarization unit arranges itself in the space in a periodic manner, leading to the formation of a polarization field along a special direction. Therefore, the created built-in electric field of the nanoplate composites of BFO/RGO is improved upon the increase of the amount of RGO. As expected, carrier separation is enhanced by the built-in electric field, therefore substantially enhancing the photoelectrochemical (PEC) activity of water splitting compared to pure BFO under the irradiation of visible-light.