Simultaneous hydrogen and peroxide production by photocatalytic water splitting

Photocatalytic oxidation of water is a promising method to realize large-scale H₂O₂ production without a hazardous and energy-intensive process. In this study, we introduce a Pt/TiO₂(anatase) photocatalyst to construct a simple and environmentally friendly system to achieve simultaneous H₂ and H₂O₂ production. Both H₂ and H₂O₂ are high-value chemicals, and their separation is automatic. Even without the assistance of a sacrificial agent, the system can reach an efficiency of 7410 and 5096 μmol g^–1 h^–1 (first 1 h) for H₂ and H₂O₂, respectively, which is much higher than that of a commercial Pt/TiO₂(anatase) system that has a similar morphology. This exceptional activity is attributed to the more favorable two-electron oxidation of water to H₂O₂, compared with the four-electron oxidation of water to O₂.     

光催化完全分解水制氢研究进展

由完全分解水的特殊性出发,从材料的结构和能带设计以及材料的表面修饰等方面对完全分解水光催化剂的研制及其分解水产氢产氧性能进行了评述.介绍了Z型体系在完全分解水制氢方面的原理,以及目前已经开发出来的几个Z型体系.对光催化完全分解水研究中存在的问题进行了简单分析.     

Lithium niobate nanowires for photocatalytic water splitting

Molecule-based preparation of lithium niobate nanowires was achieved by proper combination of a niobium oxooxalate complex, a structure-directing reagent, and a lithium source. Structural and photophysical properties of the nanowires obtained were characterized by several microscopic and spectroscopic techniques. The nanowire was employed as a photocatalyst for overall water splitting, and H(2) or O(2) evolution reaction from an aqueous solution containing a sacrificial reagent under UV light irradiation to show enhanced photocatalytic properties as compared with a bulky counterpart prepared by a solid state reaction. The factors contributing to the enhancement of the photocatalytic performance were suggested to be an increase in active sites for the photocatalytic reaction in conjunction with a large surface area and a small particle size.     

光催化分解水制氢反应中助催化剂的作用及机理（英文）

近年来,随着一次能源过度消耗所带来的能源和环境问题日益突出,开发廉价、可持续的清洁能源备受关注.光催化分解水制氢可利用太阳能普遍率高和几乎免费等特点制取燃烧热值高、燃烧产物无污染的氢气能源.自从1972年日本的Fujishima教授和Honda教授首次发现TiO₂单晶电极光催化分解水可以产生氢气以来,光催化制氢被认为是实现可持续制氢最有潜力的方法之一.有效地将太阳能转换为化学能的关键是设计高效的电荷分离和运输结构.然而,现有的大多数半导体光催化剂因缺少活性位点、光生载流子易复合等缺点而无法达到较高的转换效率.因此,如何提高半导体光催化产氢的转换效率是现阶段面对的重要问题.在众多解决方法中,助催化剂的引入可以为光催化制氢反应增加活性位点,促进光生载流子的有效分离,进而有效地提高半导体光催化产氢速率.本文总结了多种不同类型的助催化剂应用于光催化产氢研究的最新进展,详细讨论了助催化剂在增强光吸收、提供活性位点、增加催化剂稳定性和促进电荷分离等方面的作用,阐明了助催化剂在光催化分解水制氢中的反应机理,同时还提出了光催化制氢的未来研究和预测.本文将助催化剂分为以下几种类别进...     

Photocatalytic water splitting for hydrogen production

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Computational model of photocatalytic water splitting

The photochemistry of a supramolecular system consisting of a (truncated) chlorophyll, benzoquinone and water has been explored with ab initio computational methods. It is shown that this photosynthetic model system can split a water molecule upon the absorption of a visible photon via an electron-driven proton-transfer process. It is suggested that the coupled transfer of an electron and a proton in hydrogen-bonded systems is mechanistically superior to electronic charge separation in covalently bonded donor-bridge-acceptor systems.     

An electrolytic device for preparation of hydrogen and oxygen from water for isotopic analysis

An electrolytic device for decomposition of water has been developed which readily gives hydrogen and oxygen for isotopic measurement with a mass spectrometer. A 20-mul sample can be decomposed quantitatively in 10 min with good reproducibility. The results produced are comparable with those obtained by reduction with uranium.     

A nano-engineered graphene/carbon nitride hybrid for photocatalytic hydrogen evolution

A metal-free photocatalytic hydrogen evolution system was successfully fabricated using heteroatom doped graphene materials as electron-transfer co-catalysts and carbon nitride as a semiconductor. The catalytic role of graphene is significantly dependent on the heteroatom dopant of the graphene, such as O, S, B, N doped/undoped graphene co-catalysts, and N-graphene shows the best catalytic hydrogen evolution rate.     

MOF-derived NiCo bimetallic cocatalyst for enhanced photocatalytic overall water splitting

The development of stable and efficient non-noble metal cocatalysts has arisen as a promising yet challenging endeavor in the context of photocatalytic overall water splitting.In this study,NiCo alloy cocatalysts were synthesized with nickel/cobalt metal organic framework （NiCo-MOF） as source of nickel and cobalt.Systematic characterization results demonstrate the successful deposition of alloy cocatalysts onto the surface of SrTiO₃.The prepared SrTiO₃ loaded NiCo-alloy can generate hydrogen and oxygen in a stoichiometric ratio for photocatalytic overall water splitting,achieving an apparent quantum yield of 11.9%at 350±10 nm.Theoretical calculations indicate that the introduction of cobalt has a beneficial regulatory effect on the hydrogen evolution sites of Ni,reducing the free energy of H adsorption.The synergistic catalytic effect of bimetallic catalysts contributes to enhancing photocatalytic activity and stability.This study offers constructive insights for the development of high-efficiency and cost-effective cocatalyst systems.     

Improved activity of SnO for the photocatalytic oxygen evolution

SnO prepared by soft chemistry exhibits a black color and semiconducting properties. The X-ray diffraction indicates a tetragonal symmetry (SG: P4/nmm) with nano crystallites of an average size of 85 nm. The forbidden band, determined from the diffuse reflectance is found to be 1.46 eV. The electrical conductivity occurs by polaron hopping and follows an Arrhenius type law with activation energy of 0.21 eV, the change in the slope at 526 K is attributed to the oxidation to SnO₂. The photo-electrochemical study shows n type conduction with a flat band potential of ?0.45 V, close to the photocurrent onset potential (?0.40 V). The electrochemical impedance spectroscopy shows the bulk contribution of SnO (R_b = 1.7 kΩ cm²) and decreases down to 1.89 kΩ cm² under illumination. The photocatalytic properties have been evaluated for the first time for to the oxygen evolution. The valence band, deriving from Sn²⁺: 5p orbital with a potential (?0.80 V_SCE/5.55 eV), is suitably positioned with respect to O₂/H₂O level (～0.6 V_SCE), leading to water oxidation under visible light. The best performance occurs at pH ～ 7 with an oxygen liberation rate of 23 µmol mL h^?1 (mg catalyst)^?1 and a quantum efficiency of 1.2%. An improvement of ～13% is observed on the system SnO/clay.     

Heterostructured MOFs photocatalysts for water splitting to produce hydrogen

Metal-organic frameworks (MOFs) with high designability and structure diversity have been widely developed as promising photocatalytic materials,but most of the...     

Tetra-armed conjugated microporous polymers for gas adsorption and photocatalytic hydrogen evolution

Two novel tetra-armed conjugated microporous polymers with different geometries have been designed and synthesized via Suzuki-Miyaura cross coupling polycondensation. Both polymers are stable in various organic solvents tested and are thermally stable. The pyrene-containing polymer of PrPy with the rigid pyrene unit shows a higher Brunauer-Emmet-Teller specific surface area of 1219 m~2 g~(-1) than the tetraphenylethylene-containing polymer of PrTPE(770 m~2 g~(-1)), which leads to a high CO_2 uptake ability of 3.89 mmol g~(-1) at 1.13 bar/273 K and a H_2 uptake ability of 1.69 wt% at 1.13 bar/77 K. The photocatalytic hydrogen production experiments revealed that PrPy also shows a better photocatalytic performance than PrTPE due to the higher conjugation degree and planar structure, the broader UV-visible(UV-Vis) absorption, the lower photoluminescence lifetime, and the higher specific surface area.     

Effects of activation and inhibition by oxygen of the photocatalytic evolution of hydrogen from alcohol-water media

Acceleration by oxygen of the photocatalytic evolution of H₂ from an H₂O-C₂H₅OH mixture has been detected. A mechanism of the process is proposed that includes formation of CH₃CHOH radicals on a semiconductor photocatalyst, their reaction with O₂, and fragmentation of radical products with formation of H atoms, which dehydrogenate C₂H₅OH, forming additional amounts of H₂.Translated from Teoreticheskaya i Éxperimental'naya Khimiya, Vol. 30, No. 1, pp. 30–33, January–February, 1994.We thank the Fundamental Research Fund of Ukraine for its support of this work.     

Application of metal chalcogenide-based anodic electrocatalyst toward substituting oxygen evolution reaction in water splitting

Electrochemical water splitting for producing hydrogen has received increasing attention. However, the large overpotential of oxygen evolution reaction (OER) is a bottleneck in water splitting. Exploiting value-added alternative reactions to replace the OER semi-reaction in water splitting can not only produce valuable products at both electrodes, but also reduce the overpotential of water splitting. Recently, metal chalcogenides (sulfides and selenides) have been widely studied in electrocatalytic reactions. This review concentrates on the recent application of metal chalcogenides in value-added anodic reactions by replacing the OER during electrochemical water splitting, including urea oxidation reaction (UOR), 5-hydroxymethylfurfural electrochemical oxidation reaction (HMF-EOR), which provides the guidance for the rational design of advanced metal chalcogenide electrocatalysts in renewable energy.     

Machine learning aided design of perovskite oxide materials for photocatalytic water splitting

Suffering from the inefficient traditional trial-and-error methods and the huge searching space filled by millions of candidates,discovering new perovskite visi...     

单分散Ni簇锚定在CN上用于高效光催化析氢

利用太阳光在常温常压下驱动光催化反应高效进行是解决人类面临的能源、环境问题从而实现绿色化学的理想方案之一.然而,兼顾效率、成本和稳定性的高性能光催化体系的研究依然存在巨大的挑战.石墨氮化碳(g-C3N4)基光催化剂由于高稳定性、无毒无害和适合的能带结构,在光催化制氢方面存在巨大潜力.然而,表面的慢反应速率导致了光生电子...     

Quantum confinement controlled photocatalytic water splitting by suspended CdSe nanocrystals

The photocatalytic hydrogen production of CdSe nanocrystals (1.75-4.81 nm) in the presence of aqueous sodium sulphite depends exponentially on the bandgap of the particles, confirming that the material's activity is controlled by the degree of quantum confinement.