物理化学学报

所属专题: 光催化剂

最新录用    

光催化全解水助催化剂的设计与构建

孙尚聪1,2, 张旭雅1,2, 刘显龙1, 潘伦1,2, 张香文1,2, 邹吉军1,2   

  1. 1 天津大学化工学院, 绿色合成与转化教育部重点实验室, 天津 300072;
    2 天津化学化工协同创新中心, 天津 300072
  • 收稿日期:2019-05-02 修回日期:2019-05-25 录用日期:2019-06-03 发布日期:2019-06-05
  • 通讯作者: 邹吉军 E-mail:jj_zou@tju.edu.cn
  • 基金资助:
    国家自然科学基金(21676193,51661145026,21506156)资助项目

Design and Construction of Cocatalysts for Photocatalytic Water Splitting

SUN Shangcong1,2, ZHANG Xuya1,2, LIU Xianlong1, PAN Lun1,2, ZHANG Xiangwen1,2, ZOU Ji-Jun1,2   

  1. 1 Key Laboratory for Green Chemical Technology of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China;
    2 Collaborative Innovative Center of Chemical Science and Engineering(Tianjin), Tianjin 300072, P. R. China
  • Received:2019-05-02 Revised:2019-05-25 Accepted:2019-06-03 Published:2019-06-05
  • Contact: ZOU Ji-Jun E-mail:jj_zou@tju.edu.cn
  • Supported by:
    The project was supported by National Natural Science Foundation of China (21676193, 51661145026, 21506156).

摘要: 能源和环境危机是当今社会面临的两大关键课题,利用太阳光驱动化学反应、将太阳能转化为化学能是解决上述问题的重要措施。通过光催化分解水是直接利用太阳能生产氢燃料的有效策略。光催化水分解过程可以分为三个基元步骤:光吸收、电荷分离与迁移、以及表面氧化还原反应。助催化剂可有效提高电荷分离效率、提供反应活性位点并抑制催化剂光腐蚀的发生,进而提高水分解效率。助催化剂也可以通过活化水分子以提高表面氧化还原动力学,进而提升整体光催化反应的太阳能转换效率。本文综述了助催化剂在光催化反应中的重要作用以及目前常用的助催化剂类型,详细说明了在光催化全解水过程中双助催化剂体系的构建及作用机理,并根据限制全解水的关键因素提出了新型助催化剂的设计策略。

关键词: 光催化水分解, 助催化剂, 电荷分离, 水分子活化

Abstract: Converting solar light into chemical energy is currently a hot topic for addressing the worldwide energy and environmental crises. However, the utilization of solar energy greatly suffers from its low energy flow density and discontinuous space-time distribution, which are essential for a reasonable energy conversion strategy toward effective storage and utilization. To this end, photocatalytic water splitting is a promising method for utilizing solar light to produce environmentally friendly hydrogen energy; yet, the efficiency needs to be improved. Generally, such processes can be divided into three elementary steps:light absorption, charge separation and migration, and surface redox reaction. The overall performance is determined by the cumulative efficiencies of the above three steps. The construction of cocatalysts is among the extensive efforts taken to improve the solar conversion efficiency. First, the cocatalysts possess higher work function than the semiconductors, and the photogenerated electrons migrate from semiconductor to cocatalysts, thereby promoting the charge separation. Second, cocatalysts usually lower the activation energy and provide abundant surface reactive sites. Particularly, the addition of cocatalysts can remarkably accelerate the four-electron transfer O2 evolution kinetics, which usually requires much higher overpotential and is often considered as the bottleneck for water splitting. Third, cocatalysts can timely remove the photogenerated charges from the surface of the semiconductor and subsequently inhibit the photocorrosion and improve the stability of the photocatalysts. Moreover, the cocatalysts also retard the backward recombination of H2 and O2. In general, cocatalysts for water splitting can be classified into three categories:H2 evolution cocatalysts, O2 evolution cocatalysts, and dual cocatalysts. The H2 evolution cocatalysts mainly contain noble metals such as Pt, Au, and other transition metals such as Co, Ni, and Cu and their phosphides or sulfides, which are capable of trapping electrons and promoting proton reduction. The O2 evolution cocatalysts are often noble metal oxides and transition metal (hydro)oxides and corresponding phosphates, which are always efficient in adsorbing and dissociating water molecules. To realize the overall water splitting, H2 evolution cocatalysts and O2 evolution cocatalysts are often integrated on one photocatalyst, which results in the so-called dual cocatalyst system. Furthermore, the performance of cocatalysts can be improved by modulating the loading amount, morphology, particle size, etc. In addition, composites such as Pt/Ni(OH)2 cocatalyst can not only provide both H2 and O2 evolution sites but also accelerate the intrinsic surface redox kinetics by promoting H2O activation, thus being much more active than the conventional dual cocatalyst system. This review summarizes the important role and design principle of cocatalysts in photocatalytic systems. The construction and functional mechanism of H2 evolution cocatalyst, O2 evolution cocatalyst, and dual cocatalysts in overall water splitting photocatalysts are discussed in detail, and the design strategy of new cocatalysts toward water activation is proposed.

Key words: Photocatalytic water splitting, Cocatalyst, Charge separation, Water molecular activation

MSC2000: 

  • O643