EPR study of charge separation associated states and reversibility of surface bound superoxide radicals in SrTiO_(3) photocatalyst  

作　　者：Xianwen Zhang Zheng Li Bin Zeng Can Li Hongxian Han 

机构地区：[1]State Key Laboratory of Catalysis and Dalian National Laboratory for Clean Energy,Dalian Institute of Chemical Physics,Chinese Academy of Sciences,Dalian 116023,Liaoning,China [2]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Journal of Energy Chemistry》2022年第7期388-393,I0011,共7页能源化学（英文版）

基　　金：financially supported by the National Key R&D Program of China under contact No.2017YFA0204804;the National Natural Science Foundation of China under contact Nos.21761142018,21473189 and 22088102 for supporting Fundamental Research Center of Artificial Photosynthesis(FRe CAP)。

摘　　要：Understanding the processes of charge generation, transfer and capture is important for the design and synthesis of efficient photocatalysts. In this work, light-induced charge separation and effect of O_(2) on electron transfer processes in SrTiO_(3) were investigated by electron paramagnetic resonance(EPR). It was found that photoinduced electron transfer from O_(2)- to Ti^(4+) produced Ti^(3+) and O- redox radical pairs under vacuum condition. Under oxygen atmosphere, however, surface bound superoxide radicals O_(2)-were formed by electron reduction of adsorbed oxygen at initial photoirradiation stage, and quenched by the reverse electron transfer to Ti^(4+) upon further photoirradiation. Formation of long-lived charge separation associated [Ti^(3+)---O-] species and the reversibility of surface bound superoxide radicals mediating the processes of photogenerated electrons may be accountable for the high activity of SrTiO_(3) in photocatalytic water splitting reaction.

关 键 词：PHOTOCATALYST Electron paramagnetic resonance Charge separation Superoxide radicals 

分 类 号：O643.36[理学—物理化学] O644.1[理学—化学] TQ116.2[化学工程—无机化工]