Ce Doping Boosts the Photocatalytic Activity of Ultrathin Bi₂MoO₆ Nanosheets for Toluene Selective Oxidation

Abstract

The generation of reactive oxygen species (ROS) from O2 is a critical step to boost the performance of photocatalytic toluene oxidation. However, the production of ROS is greatly limited by the serious recombination of charge carriers and the lack of O2 adsorption sites. In this work, Ce-doped Bi2MoO6 ultrathin nanosheets with rich oxygen defects are prepared by a one-step hydrothermal method. The ultrathin structure promotes the longitudinal transport of carriers to the surface. The introduction of Ce ions generates both Ce3+/Ce4+ redox ion pairs and oxygen defects in Bi2MoO6, where the former promotes the transfer of photogenerated electrons and the latter enhances the adsorption of O2, thereby producing more superoxide radicals (•O2–). Attributed to these advantages, Ce-doped Bi2MoO6 ultrathin nanosheets exhibit excellent photocatalytic activity for toluene selective oxidation. The toluene conversion rate is 4422 μmol·g–1·h–1. The selectivity values of benzaldehyde and benzyl alcohol are 84.7 and 15.3%, respectively. In addition, the mechanism of photocatalytic selective oxidation of toluene is further explored through a series of experiments.