Steering the behavior of photogenerated carriers in semiconductor photocatalysts: a new insight and perspective

Abstract

The current semiconductor photocatalysts only exhibit unsatisfactory photocatalytic efficiency due to the easy recombination of photogenerated carriers. Regulating the separation and transfer of photogenerated carriers and reducing the recombination of photogenerated carriers are essential for improving the catalytic efficiency of photocatalysts. The recombination of photogenerated carriers is produced by the attraction of Coulombic force. Consequently, reducing the recombination of photogenerated carriers requires an additional driving force to counteract the attraction of Coulombic force. However, exploring the mechanism of photogenerated carrier regulation from the perspective of the driving force of photogenerated carrier separation and transfer has received only sporadic attention. This review first starts with the fundamental mechanism of photogenerated carrier recombination and the impairment of photogenerated carrier recombination to photocatalytic performance. Then it focuses on several main strategies for regulating the behavior of photogenerated carriers from the aspect of the driving force for the separation and transfer of photogenerated carriers, including heterojunction design, construction of an intramolecular donor–acceptor (D–A) system, exciton regulation, and electron spin regulation. Subsequently, advanced characterization techniques and the latest developments of theoretical calculations in the separation and migration of photogenerated carriers have been introduced. At the end, we summarize the current challenges of photogenerated carrier regulation and put forward the prospects for future development.