Role of Vacancies in Photocatalysis: A Review of Recent Progress

Photocatalysis via direct solar-to-chemical energy conversion is an intriguing approach for alleviating the pressure of high energy consumption caused by social development. However, photocatalytic efficiency is greatly restricted by unsatisfactory light-harvesting capacity, high carrier recombination rates, and sluggish reaction kinetics. Indeed, vacancy engineering is an attractive strategy to regulate photocatalytic reaction performance to maximize the utilization and storage of solar energy. In this review, we summarize recent progress about the important roles of vacancy defects on solar-driven photocatalytic applications. The current advanced characterization techniques, especially for in situ/operando techniques, are first presented for elucidating the structure-performance relationships of defective semiconductors in photocatalysis. Subsequently, the crucial roles of vacancies in enhancing photocatalytic performance are highlighted from three important processes: light absorption, carrier separation and migration, and surface reaction. Finally, based on the above understanding, perspectives and opportunities about defective materials are considered for various photocatalytic applications.