Hefei National Laboratory for Physical Science at the Microscale, CAS Center for Excellence in Nanoscience, iChEM, Synergetic Innovation Center of Quantum Information and Quantum Physics, National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei, Anhui 230026, P.R. China.
J Am Chem Soc. 2018 Feb 7;140(5):1760-1766. doi: 10.1021/jacs.7b10997. Epub 2018 Jan 24.
Excitonic effects mediated by Coulomb interactions between photogenerated electrons and holes play crucial roles in photoinduced processes of semiconductors. In terms of photocatalysis, however, efforts have seldom been devoted to the relevant aspects. For the catalysts with giant excitonic effects, the coexisting, competitive exciton generation serves as a key obstacle to the yield of free charge carriers, and hence, transformation of excitons into free carriers would be beneficial for optimizing the charge-carrier-involved photocatalytic processes. Herein, by taking bismuth oxybromide (BiOBr) as a prototypical model system, we demonstrate that excitons can be effectively dissociated into charge carriers with the incorporation of oxygen vacancy, leading to excellent performances in charge-carrier-involved photocatalytic reactions such as superoxide generation and selective organic syntheses under visible-light illumination. This work not only establishes an in-depth understanding of defective structures in photocatalysts but also paves the way for excitonic regulation via defect engineering.
激子相互作用通过光生电子和空穴之间的库仑相互作用介导，在半导体的光诱导过程中起着至关重要的作用。然而，就光催化而言，很少有人关注相关方面。对于具有巨大激子效应的催化剂，共存的、竞争的激子生成是产生自由电荷载流子的关键障碍，因此，将激子转化为自由载流子将有利于优化涉及电荷载流子的光催化过程。在本文中，我们以溴氧化铋 (BiOBr) 作为典型的模型体系，证明了通过掺入氧空位可以有效地将激子解离为载流子，从而在可见光照射下的涉及电荷载流子的光催化反应（如超氧生成和选择性有机合成）中表现出优异的性能。这项工作不仅深入了解了光催化剂中的缺陷结构，而且为通过缺陷工程进行激子调控铺平了道路。
