铁基多相助催化剂光电化学水氧化研究进展

The use of fossil fuels has caused serious environmental problems such as air pollution and the greenhouse effect. Moreover, because fossil fuels are a non-renewable energy source, they cannot meet the continuously increasing demand for energy. Therefore, the development of clean and renewable energy sources is necessitated. Hydrogen energy is a clean, non-polluting renewable energy source that can ease the energy pressure of the whole society. The sunlight received by the Earth is 1.7× 10¹⁴ J in 1 s, which far exceeds the total energy consumption of humans in one year. Therefore, conversion of solar energy to valuable hydrogen energy is of significance for reducing the dependence on fossil fuels. Since Fujishima and Honda first reported on TiO₂ in 1972, it has been discovered that semiconductors can generate clean, pollution-free hydrogen through water splitting driven by electricity or light. Hydrogen generated through this approach can not only replace fossil fuels but also provide environmentally friendly renewable hydrogen energy, which has attracted considerable attention. Photoelectrochemical (PEC) water splitting can use solar energy to produce clean, sustainable hydrogen energy. Because the oxygen evolution reaction (OER) over a photoanode is sluggish, the overall energy conversion efficiency is considerably low, limiting the practical application of PEC water splitting. A cocatalyst is, thus, necessary to improve PEC water splitting performance. So far, the synthesis of first-row transition-metal-based (e.g., Fe, Co, Ni, and Mn) cocatalysts has been intensively studied. Iron is earth-abundant and less toxic than other transition metals, making it a good cocatalyst. In addition, iron-based compounds exhibit the properties of a semiconductor/metal and have unique electronic structures, which can improve electrical conductivity and water adsorption. Various iron-based catalysts with high activity have been designed to improve the efficiency of PEC water oxidation. This article briefly summarizes the research progress related to the structure, synthesis, and application of iron oxyhydroxides, iron-based layered double hydroxides, and iron-based perovskites and discusses the evaluation of the performance of these cocatalysts toward photoelectrochemical water oxidation.      

Water‐Splitting Catalysis and Solar Fuel Devices: Artificial Leaves on the Move

The development of new energy materials that can be utilized to make renewable and clean fuels from abundant and easily accessible resources is among the most challenging and demanding tasks in science today. Solar‐powered catalytic water‐splitting processes can be exploited as a source of electrons and protons to make clean renewable fuels, such as hydrogen, and in the sequestration of CO₂ and its conversion into low‐carbon energy carriers. Recently, there have been tremendous efforts to build up a stand‐alone solar‐to‐fuel conversion device, the “artificial leaf”, using light and water as raw materials. An overview of the recent progress in electrochemical and photo‐electrocatalytic water splitting devices is presented, using both molecular water oxidation complexes (WOCs) and nano‐structured assemblies to develop an artificial photosynthetic system.     

Efficient solar generation of hydrogen fuel – a fundamental analysis

Solar water splitting can provide clean, renewable sources of hydrogen fuel, although prior models had indicated only low conversion efficiencies would be attainable. A novel model is derived for electrochemical solar water splitting processes by semiconductors, which is the first derivation of band edge restricted thermal enhanced solar water splitting efficiencies. A theoretical basis is developed for solar energy conversion efficiencies in the 50% range as determined with contemporary thermodynamic values. The theory combines photodriven charge transfer, with excess sub-bandgap insolation to lower the water potential, providing a process of highly efficient elevated temperature solar electrolysis of water to hydrogen fuel.     

Research Progress of Ferrite Materials for Photoelectrochemical Water Splitting

Photoelectrochemical(PEC)water splitting is an effective strategy to convert solar energy into clean and renewable hydrogen energy.In order to carry out effective PEC conversion,researchers have conducted a lot of exploration and developed a variety of semiconductors suitable for PEC water splitting.Among them,metal oxides stand out due to their higher stability.Compared with traditional oxide semiconductors,ferrite-based photoelectrodes have the advantages of low cost,small band gap,and good stability.Interestingly,due to the unique characteristics of ferrite,most of them have various tunable features,which will be more conducive to the development of efficient PEC electrode.However,this complex metal oxide is also troubled by severe charge recombination and low carrier transport efficiency,resulting in lower conversion efficiency compared to theoretical value.Based on this,this article reviews the structure,preparation methods,characteristics and modification strategies of various common ferrites.In addition,we analyzed the future research direction of ferrite for PEC water splitting,and looked forward to the development of more efficient catalysts.     

Chlorophyll sensitized BiVO4 as photoanode for solar water splitting and CO2 conversion

Converting solar energy into valuable hydrogen and hydrocarbon fuels through photoelectrocatalytic water splitting and CO_2 reduction is highly promising in addressing the growing demand for renewable and clean energy resources. However, the solar-to-fuel conversion efficiency is still very low due to limited light absorption and rapid bulk recombination of charge carriers. In this work, we present chlorophyll(Chl) and its derivative sodium copper chlorophyllin(ChlCuNa), as dye sensitizers, modified BiVO_4 to improve the photoelectrochemical(PEC) performance. The photocurrent of BiVO_4 is surprisingly decreased after a direct sensitization of Chl while the sensitization of ChlCuNa obviously enhances photocurrent of BiV04 electrodes by improved surface hydrophilicity and extended light absorption.ChlCuNa-sensitized BiV04 achieves an improved H_2 evolution rate of 5.43 μmol h~(-1) cm~(-2) in water splitting and an enhanced HCOOH production rate of 2.15 μmol h~(-1) cm~(-2) in CO_2 PEC reduction, which are1.9 times and 2.4 times higher than pristine BiVO_4, respectively. It is suggested that the derivative ChlCuNa is a more effective sensitizer for solar-to-fuel energy conversion and CO_2 utilization than Chl.     

Recent progress in carbon-based materials boosting electrochemical water splitting

As environmental crises such as global warming become more and more serious due to the large amount of carbon dioxide emitted by the burning of fossil fuels, much attention has been paid to carbon neutrality. Hydrogen, with zero carbon content, is a clean and renewable energy carrier having a large energy density. It is considered as one of the most desirable alternatives to fossil fuels. Electrochemical water splitting, unlike the steam reforming process accelerating fossil fuels depletion and CO₂ emissions, can produce H₂ powered by renewable energy such as solar or wind. As a promising way to promote carbon neutralization, hydrogen production by electrolysis of water is meaningful both in terms of scientific research and practical application. In order to drive electrochemical water splitting with low power consumption, efficient, durable and affordable electrocatalysts with low overpotentials are in urgent need. Therefore, this mini-review briefly introduces the current development status and mainstream obstacles of carbon-based materials used in electrochemical water splitting.     

Near infrared-driven photoelectrochemical water splitting: Review and future prospects

Photoelectrochemical (PEC) water splitting supplies an environmentally friendly, sustainable approach to generating renewable hydrogen fuels. Oxides semiconductors, e.g. TiO₂, BiVO₄, and Fe₂O₃, have been widely developed as photoelectrodes to demonstrate the utility in PEC systems. Even though significant effort has been made to increase the PEC efficiency, these materials are still far from practical applications. The main issue of metal oxides is the wide bandgap energy that hinders effective photons harvesting from sunlight. In solar spectrum, over 40% of the energy is located in the near-infrared (NIR) region. Developing sophisticated PEC systems that can be driven by NIR illumination is therefore essential. This review gives a concise overview on PEC systems based on the use of NIR-driven photoelectrodes. Promising candidates as efficient yet practical NIR-responsive photoelectrodes are suggested and discussed. Future outlooks on the advancement of PEC water splitting are also proposed.     

Progress of transition metal chalcogenides as efficient electrocatalysts for energy conversion

The continuous excessive usage of fossil fuels has resulted in its fast depletion, leading to an escalating energy crisis as well as several environmental issues leading to increased research towards sustainable energy conversion. Electrocatalysts play crucial role in the development of numerous novel energy conversion devices, including fuel cells and solar fuel generators. In particular, high-efficiency and cost-effective catalysts are required for large-scale implementation of these new devices. Over the last few years, transition metal chalcogenides have emerged as highly efficient electrocatalysts for several electrochemical devices such as water splitting, carbon dioxide electroreduction, and, solar energy converters. These transition metal chalcogenides exhibit high electrochemical tunability, abundant active sites, and superior electrical conductivity. Hence, they have been actively explored for various electrocatalytic activities. Herein, we have provided comprehensive review of transition-metal chalcogenide electrocatalysts for hydrogen evolution, oxygen evolution, and carbon dioxide reduction and illustrated structure–property correlation that increases their catalytic activity.     

Conversion of Solar Energy to Fuels by Inorganic Heterogeneous Systems

Over the last several years,the need to find clean and renewable energy sources has increased rapidly because current fossil fuels will not only eventually be depleted,but their continuous combustion leads to a dramatic increase in the carbon dioxide amount in atmosphere.Utilisation of the Sun’s radiation can provide a solution to both problems.Hydrogen fuel can be generated by using solar energy to split water,and liquid fuels can be produced via direct CO2 photoreduction.This would create an essentially free carbon or at least carbon neutral energy cycle.In this tutorial review,the current progress in fuels’ generation directly driven by solar energy is summarised.Fundamental mechanisms are discussed with suggestions for future research.     

应用于有机加氢反应的等离激元催化材料设计

金属纳米晶体具有独特的表面等离激元特性,为太阳能转换成化学能提供了新的机遇。本文以课题组近期的研究工作为例,阐述在催化有机加氢反应中表面等离激元效应所产生的多种物理过程的作用机制。该系列工作实现了太阳能向化学能的有效转换,为太阳能替代传统有机化工中的热催化提供了可能性,对等离激元催化材料的设计具有一定的指导意义。     

硫氧键合BiVO4光阳极与FeNi催化剂实现高效水氧化

光电催化分解水可以将充足的太阳能直接转化存储为绿色清洁的氢能,然而光阳极表面缓慢的析氧反应动力学严重限制了太阳能到氢能的转化效率。我们通过一种简单的S-O键合策略实现BiVO4光阳极与FeNi催化剂的界面耦合（S:BiVO4-FeNi）,其光电催化分解水的光电流达到6.43 mA/cm2（1.23 VRHE, AM 1.5G）。进一步研究结果表明：界面S-O键合能够有效实现BiVO4光阳极光生电荷分离并促进空穴向FeNi催化剂表面迁移。同时,S-O键合可以进一步调控FeNi催化剂表面的电荷分布,从而有效提高光电化学分解水析氧活性和稳定性。该工作为设计构建具有高效、稳定的太阳能光电催化分解水体系提供了一种新的研究策略。     

电池电极反应的新应用：分步法电解制氢气

可再生能源与电解水制氢技术的结合是实现可持续制氢的最佳途径. 然而,传统电解水技术中解决氢-氧同时、同步、同地产生的问题必须依赖于膜分离技术,大幅限制了氢-氧分离和氢气异地运输的灵活性,并阻碍了可再生能源(如风能、太阳能)与电解水技术的直接结合. 针对上述问题,作者课题组在近期提出了基于电池电极反应的分步法电解水制氢技术,即通过电池电极的可逆电化学反应将现有电解水过程拆分为制氢和制氧分立步骤,实现在无膜条件下氢气和氧气的分时、分地交替制备,提升了电解水制氢的灵活性,促进了可再生能源向氢能的直接转化. 本文将介绍这一新技术的研究进展,并分析这一技术的优点和面临的挑战.     

Atomically precise Au25(GSH)18 nanoclusters versus plasmonic Au nanocrystals: Evaluating charge impetus in solar water oxidation

Atomically precise metal nanoclusters (NCs) have been deemed as an emerging class of metal nanomaterials owing to fascinating size-dependent physicochemical properties, discrete energy band structure, and quantum confinement effect, which are distinct from conventional metal nanoparticles (NPs). Nevertheless, metal NCs suffer from photoinduced self-oxidative aggregation accompanied by in-situ transformation to metal NPs, markedly reducing the photosensitization of metal NCs. Herein, maneuvering the generic instability of metal NCs, we perform the charge transport impetus comparison between atomically precise metal NCs and plasmonic metal NPs counterpart obtained from in-situ self-transformation of metal NCs in photoelectrochemical (PEC) water splitting reaction. For conceptual demonstration, we proposed two quintessential heterostructures, which include TNTAs-Au₂₅ heterostructure fabricated by electrostatically depositing glutathione (GSH)-protected Au₂₅(GSH)₁₈ NCs on the TiO₂ nanotube arrays (TNTAs) substrate, and TNTAs-Au heterostructure constructed by triggering self-transformation of Au₂₅(GSH)₁₈ NCs to plasmonic Au NPs in TNTAs-Au₂₅ via calcination. The results indicate that photoelectrons produced over Au₂₅ NCs are superior to hot electrons of plasmonic Au NPs in stimulating the interracial charge transport toward solar water oxidation. This is mainly ascribed to the significantly accelerated carrier transport kinetics, prolonged carrier lifespan, and substantial photosensitization effect of Au₂₅ NCs compared with plasmonic Au NPs, resulting in the considerably enhanced PEC water splitting performance of TNTAs-Au₂₅ relative to plasmonic TNTAs-Au counterpart under visible light irradiation. Our work would provide important implications for rationally designing atomically precise metal NCs-based photosystems toward solar energy conversion.     

Solar Electricity and Solar Fuels: Status and Perspectives in the Context of the Energy Transition

The energy transition from fossil fuels to renewables is already ongoing, but it will be a long and difficult process because the energy system is a gigantic and complex machine. Key renewable energy production data show the remarkable growth of solar electricity technologies and indicate that crystalline silicon photovoltaics (PV) and wind turbines are the workhorses of the first wave of renewable energy deployment on the TW scale around the globe. The other PV alternatives (e.g., copper/indium/gallium/selenide (CIGS) or CdTe), along with other less mature options, are critically analyzed. As far as fuels are concerned, the situation is significantly more complex because making chemicals with sunshine is far more complicated than generating electric current. The prime solar artificial fuel is molecular hydrogen, which is characterized by an excellent combination of chemical and physical properties. The routes to make it from solar energy (photoelectrochemical cells (PEC), dye‐sensitized photoelectrochemical cells (DSPEC), PV electrolyzers) and then synthetic liquid fuels are presented, with discussion on economic aspects. The interconversion between electricity and hydrogen, two energy carriers directly produced by sunlight, will be a key tool to distribute renewable energies with the highest flexibility. The discussion takes into account two concepts that are often overlooked: the energy return on investment (EROI) and the limited availability of natural resources—particularly minerals—which are needed to manufacture energy converters and storage devices on a multi‐TW scale.     

Visible‐Light‐Responsive Photoanodes for Highly Active,Stable Water Oxidation

Solar energy is a natural and effectively permanent resource and so the conversion of solar radiation into chemical or electrical energy is an attractive, although challenging, prospect. Photo‐electrochemical (PEC) water splitting is a key aspect of producing hydrogen from solar power. However, practical water oxidation over photoanodes (in combination with water reduction at a photocathode) in PEC cells is currently difficult to achieve because of the large overpotentials in the reaction kinetics and the inefficient photoactivity of the semiconductors. The development of semiconductors that allow high solar‐to‐hydrogen conversion efficiencies and the utilization of these materials in photoanodes will be a necessary aspect of achieving efficient, stable water oxidation. This Review discusses advances in water oxidation activity over photoanodes of n‐type visible‐light‐responsive (oxy)nitrides and oxides.     

氧化物钙钛矿的光催化研究进展：CO2还原、水裂解、固氮

At present, more than 80% of the world's energy demand is fulfilled by the burning of fossil fuels, which has caused the production of a large amount of greenhouse gases, leading to global warming and damage to the environment. The high consumption of fossil fuels every year causes the energy crisis to become increasingly serious. Finding a sustainable and pollution-free energy source is therefore essential. Among all forms of energy sources, solar energy is preferred because of its cleanliness and inexhaustible availability. The energy provided by one year of sunlight is more than 100 times the total energy in known fossil fuel reserves worldwide; however, the extent of solar energy currently used by mankind each year is minute; thus developments in solar energy are imperative. To address the urgent need for a renewable energy supply and to solve environmental problems, a variety of technologies in the field of photocatalysis have been developed. Photocatalytic technology has attracted significant attention because of its superior ability to convert clean solar energy into chemical fuels. Among the photocatalytic materials emerging in an endless stream, perovskite oxide, with the general formula of ABO₃, has great potential in the fields of solar cells and photocatalysis as each site can be replaced by a variety of cations. Furthermore, owing to its unique properties such as high activity, robust stability, and facile structure adjustment, perovskite oxide photocatalysts have been widely used in water decomposition, carbon dioxide reduction and conversion, and nitrogen fixation. In terms of carbon dioxide reduction, oxide perovskites can achieve precise band gap and band edge tuning owing to its long charge diffusion length and flexibility in composition. For the development and utilization of solar energy in the environmental field, perovskite oxide and its derivatives (layered perovskite oxide) are used as photocatalysts for water decomposition and environmental remediation. In terms of nitrogen fixation, the conventional Haber-Bosh process for ammonia synthesis, which has been widely used in the past, requires high temperature and high energy. Therefore, we summarize the recent advances in perovskite oxide photocatalysts for nitrogen fixation from the aspect of activating the adsorbed N₂ by weakening the N $ \equiv $N triple bond, promoting charge separation, and accelerating the charge transfer to the active sites to realize the photochemical reaction. Overall, this review article presents the structure and synthesis of perovskite oxide photocatalysis, focusing on the application of photocatalysis in water splitting, carbon dioxide reduction, and nitrogen fixation. This review concludes by presenting the current challenges and future prospects of perovskite oxide photocatalysts.      

NIR-plasmon-enhanced Systems for Energy Conversion and Environmental Remediation

The introduction of plasmons is an important method to solve the insufficient utilization of the full spectrum of solar energy by semiconductor catalysts. However, semiconductor catalysts combined with traditional noble metal plasmons(Au, Ag) can only extend the absorption spectrum to partially visible light. In order to further improve the photoenergy absorption efficiency of catalysts, they need to be able to effectively utilize near-infrared light, which has become a new research direction. Recent studies have shown that traditional noble metal plasmons can absorb a part of NIR through special morphology, size control and material composite. At the same time, gratifying achievements have been made in the application of plasmonic semiconductors with broad spectrum absorption in catalysis. This article reviews the principles of generating and regulating plasmonic effects in different catalytic systems. The applications of plasmon absorption of near-infrared light in energy conversion and environmental remediation have also been presented.     

光电催化用于高附加值化学品合成

化石燃料的过度消耗导致了能源短缺和环境破坏,因此可再生清洁能源的开发已成为当务之急.在众多可再生能源中,太阳能因其环境友好,储量巨大且分布广泛等特点而引起了研究者们的兴趣.光电催化(PEC)是一种能够将可再生太阳能转化为化学能的方法,而最受关注的是通过PEC水分解来获得高附加值的氢能源.欲使PEC系统实现水分解,理论上...     

Recent Progress on Nickel-Based Oxide/(Oxy)Hydroxide Electrocatalysts for the Oxygen Evolution Reaction

Developing clean and sustainable energies as alternatives to fossil fuels is in strong demand within modern society. The oxygen evolution reaction (OER) is the efficiency-limiting process in plenty of key renewable energy systems, such as electrochemical water splitting and rechargeable metal–air batteries. In this regard, ongoing efforts have been devoted to seeking high-performance electrocatalysts for enhanced energy conversion efficiency. Apart from traditional precious-metal-based catalysts, nickel-based compounds are the most promising earth-abundant OER catalysts, attracting ever-increasing interest due to high activity and stability. In this review, the recent progress on nickel-based oxide and (oxy)hydroxide composites for water oxidation catalysis in terms of materials design/synthesis and electrochemical performance is summarized. Some underlying mechanisms to profoundly understand the catalytic active sites are also highlighted. In addition, the future research trends and perspectives on the development of Ni-based OER electrocatalysts are discussed.     

基于立方烷结构的分子催化剂在光催化水氧化中的研究进展

随着化石燃料大量使用带来的气候变化和环境污染问题日趋严重,寻找清洁高效的可再生能源用做传统化石燃料的替代品,已经成为当前的研究热点。光驱动的水分解反应被认为是太阳能制氢的可行途径。水的全分解包括两个半反应-水的氧化和质子还原。其中水的氧化反应是一个涉及四个电子和四个质子转移的复杂过程,需要很高的活化能,被认为是全分解水反应的瓶颈步骤。因此,开发高效、稳定、廉价丰产的水氧化催化剂是人工光合作用突破的关键因素。立方烷具有类似自然界光合作用酶光系统II(PSII)活性中心Mn_4CaO_5簇的结构,世界各国的科学家受自然界光合作用的启发,开发出了许多基于过渡金属的立方烷结构的催化剂,常见的有锰、钴和铜等立方烷催化剂。本文简要地综述了近年来立方烷分子催化剂在光催化水氧化中的研究进展。首先介绍了立方烷基光催化水氧化反应历程,继而详细介绍了基于有机配体的立方烷配合物和全无机的多金属氧酸盐立方烷水氧化催化剂,其次是半导体(BiVO4或聚合的氮化碳(PCN))为捕光材料复合立方烷分子催化剂的水氧化体系最新研究进展。最后总结并展望了该领域所面临的挑战及其前景。