Research progress on the heterogeneous photocatalytic selective oxidation of benzene to phenol

Phenol is important for the manufacture of phenolic chemicals. The current cumene process for phenol production requires harsh conditions and suffers from unwanted side products. Nowadays, the one step conversion of benzene to phenol has received much attention. However, because of the obscurity in benzene C(sp2)–H bond activation and the easy oxidation of phenol, the direct oxidation of benzene to phenol is challenging. As an alternative, the photocatalytic selective oxidation of benzene into phenol under mild conditions is considered promising. In this review, we systematically summarize the recent advance of heterogeneous photocatalytic oxidation of benzene, including those of design principles and various modification strategies, mechanistic understanding determined based on in situ characterization and density functional theory calculation, factors affecting kinetics of the reaction, reactor design and photocatalyst deactivation. It is envisaged that photocatalysts made up of single atoms, layered double hydroxides, and metal clusters are good candidates. At the end of this article, the perspective of catalyst design and strategies for the exploration of reaction mechanism are discussed, emphasizing on the use of state-of-the-art techniques. Moreover, the design of photocatalytic reactors for the realization of the photocatalytic process is considered.