Abstract:

Photoelectrocatalytic(PEC) water splitting offers a promising approach to convert solar energy into hydrogen energy. The photoelectrode, as the core of the PEC water splitting system, determines the photo-conversion efficiency. Among various semiconductors, zinc oxide (ZnO) has attracted much attention owing to its low onset potential, high charge mobility and low cost. However, ZnO possesses a wide band gap, the serious recombination of electron-hole pairs and sluggish kinetics of the oxygen evolution reaction, which greatly restrict their photo-conversion efficiency. In this review, the recent advances in the fabrication of ZnO-based photoanode and its PEC performances were discussed. Firstly, the effect of the morphology and intrinsic defect in ZnO semiconductor on the PEC properties were elaborated. Then, several strategies that can be employed for construction the surface/interface of ZnO-based semiconductors were discussed, including element doping, quantum dot sensitization, noble metal deposition, heterostructure and coupling the cocatalysts. The effects of different strategies on the PEC properties of ZnO-based semiconductors were also discussed. Finally, the future research directions of ZnO-based semiconductors were prospected at five aspects including surface modification of ZnO, constructing the interface of the composite semiconductor at atom level, replacing noble metal Au, Ag and Pt nanoparticles with inexpensive bimetallic or polymetallic nanoparticles, fabrication of the high efficient cocatalyst and introducing interlayers such as hole-storage layers or electron-blocking layers.

Key words: zonc oxide, nanostructure, photoelectrocatalysis, catalyst, solar energy

摘要：

光电催化水分解制取氢气是最理想的制氢技术之一。光电极材料作为光电催化水分解反应系统最核心的部分，决定着太阳能到化学能的转换效率。氧化锌（ZnO）半导体因具有较低的超电势、高的电子迁移速率和价格低廉等优点，引起了广泛关注。然而，ZnO半导体的禁带较宽、电子-空穴易于复合和表面水氧化反应动力学缓慢，阻碍了其高效利用太阳能和实现理论效率。本文从ZnO的微纳结构和表界面修饰两个方面出发，综述了近年来ZnO基光电极的构筑策略及其光电催化性能的研究进展。首先阐述了ZnO的微观形貌和缺陷对光电性质的影响。然后总结了元素掺杂、量子点敏化、贵金属沉积、异质结构造和共催化剂沉积等策略对ZnO基半导体的表界面的构筑及对光电催化性能的影响。最后对未来高效ZnO基半导体光电极研究方向进行了展望，具体包括5个方面：ZnO表面改性；在原子水平构筑复合半导体催化剂的相界面；用廉价双金属或多金属纳米颗粒取代纯贵金属Au、Ag和Pt纳米颗粒；构建高效的电催化剂助剂；在ZnO半导体和助剂界面引入空穴储存层或电子堵塞层。

关键词: 氧化锌, 纳米结构, 光电催化, 催化剂, 太阳能