Journal of Energy Chemistry ( IF 13.1 ) Pub Date : 2022-03-01 , DOI: 10.1016/j.jechem.2022.02.038 Xianwen Zhang 1, 2 , Zheng Li 1 , Bin Zeng 1, 2 , Can Li 1, 2 , Hongxian Han 1
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 O2 on electron transfer processes in SrTiO3 were investigated by electron paramagnetic resonance (EPR). It was found that photoinduced electron transfer from O2− to Ti4+ produced Ti3+ and O− redox radical pairs under vacuum condition. Under oxygen atmosphere, however, surface bound superoxide radicals O2− were formed by electron reduction of adsorbed oxygen at initial photoirradiation stage, and quenched by the reverse electron transfer to Ti4+ upon further photoirradiation. Formation of long-lived charge separation associated [Ti3+---O−] species and the reversibility of surface bound superoxide radicals mediating the processes of photogenerated electrons may be accountable for the high activity of SrTiO3 in photocatalytic water splitting reaction.
中文翻译:
SrTiO3光催化剂中电荷分离相关态和表面结合超氧自由基可逆性的EPR研究
了解电荷产生、转移和捕获的过程对于高效光催化剂的设计和合成很重要。在这项工作中,通过电子顺磁共振(EPR)研究了光诱导电荷分离和O 2对SrTiO 3中电子转移过程的影响。发现在真空条件下,从O 2-到Ti 4+的光致电子转移产生Ti 3+和O -氧化还原自由基对。然而,在氧气气氛下,表面结合的超氧自由基O 2 -在初始光辐照阶段通过吸附氧的电子还原形成,并通过向Ti的反向电子转移而猝灭4+在进一步的光辐照下。与[Ti 3+ ---O - ] 物种相关的长寿命电荷分离的形成和介导光生电子过程的表面结合超氧自由基的可逆性可能是SrTiO 3在光催化水分解反应中高活性的原因。