Abstract:

Hydrogen is recognized as the ideal “carbon neutrality” energy carrier due to its remarkable properties including high heat value, low density, storable and no carbon emission. Photoelectrochemical water splitting offers the most promising approach to convert solar energy into green hydrogen fuels. However, the sluggish surface oxygen evolution reaction on the photoanode greatly restricted the photoconversion efficiency. Introducing oxygen evolution cocatalyst on the photoanode has been proven to be a feasible strategy for promoting the charge separation, reducing the overpotential, and providing more active sites for water oxidation. Therefore, this review discusses the origin and types of cocatalyst on the photoanode surface, the influence of its micro-nano structure, and the interfacial construction strategy on water oxidation activity, and photoelectrochemical water splitting performance. Firstly, it introduces the types of cocatalyst and summarizes the roles of cocatalyst, the effect of different cocatalysts on the charge separation, transfer and stability of photoelectrode. Moreover, the influencing factors of cocatalyst on photoelectrochemical water splitting are compared and analyzed including size effect, surface defect and fluorination. Furthermore, the interface modulation strategies between cocatalyst and semiconductor are discussed such as the carrier transport channel, hole storage layer, and interface chemical bond. Finally, it discusses the focused problems and prospects the future research direction of the oxygen evolution cocatalyst. It is believed that the photoelectrochemical water splitting performance can be improved by regulating the crystal structure, cluster, single-atom and interface chemical bonding of the oxygen evolution cocatalyst. Moreover, carbonyl metal is suggested as a unique precursor for constructing oxygen evolution cocatalyst.

Key words: oxygen evolution cocatalyst, nanostructure, hydrogen production, photoelectrocatalysis, interface charge transfer, solar energy

摘要：

氢气因其热值高、质轻、可存储且无碳排放，被认为是最佳的碳中和能源载体。光电催化分解水制氢技术是目前生产绿氢最理想的技术途径之一，但光阳极表面水氧化速率极为缓慢，限制了阴极产氢效率。析氧助催化剂在水氧化反应过程中能够为其提供高效的活性中心，使反应易于发生，进而促进阴极产氢效率。本文从光阳极表面助催化剂的起源和作用出发，综述了近年来半导体光电极表面的助催化剂类型、微纳结构对水氧化活性的影响、界面构筑策略和光电性能研究进展。首先，阐述了电催化剂作为光阳极助催化剂在水氧化反应中所扮演的角色，不同助催化剂对半导体光电极的电荷分离和转移及稳定性的影响；然后，总结了助催化剂对半导体光电极光电催化活性的影响因素（尺寸效应、表面缺陷和氟化）。进一步归纳了助催化剂/半导体之间的界面优化策略（载流子传输通道、空穴储存层和界面化学键）。最后对析氧助催化剂所面临的问题和未来的发展方向进行了探讨和展望，认为通过调控析氧助催化剂的晶体结构、簇、单原子和界面化学键能够增强光阳极光电催化分解水的性能，并提出羰基金属是一种独特的构筑析氧助催化剂前体。

关键词: 析氧助催化剂, 纳米结构, 制氢, 光电催化, 界面电荷迁移, 太阳能