Surface decoration of BiPO4 with BiOBr nanoflakes to build heterostructure photocatalysts with enhanced photocatalytic activity

Abstract

BiOBr nanoflakes-decorated BiPO4 (BiOBr/BiPO4) composite photocatalysts were prepared by a simple hydrothermal method. The BiOBr nanoflakes were tightly dispersed on the surface of the BiPO4 and formed p–n heterojunctions between BiOBr and BiPO4, as evidenced by characterization of the structure and composition. The p–n heterojunctions BiOBr/BiPO4 composites could greatly improve photocatalytic activity, and the 60wt% BiOBr/BiPO4 composite showed the highest degrade rate for methylene blue (MB), which was eight times and two times than that of pure BiPO4 and BiOBr, meanwhile, the BiOBr/BiPO4 composite also exhibited superior activities for phenol degradation under visible light. The enhanced photocatalytic performance was attributed to the enhancement of visible-light absorption efficiency as well as the formation of p–n heterojunctions in BiOBr/BiPO4, which could greatly accelerate the separation efficiency of photogenerated charge carriers. In addition, the roles of the radical species were investigated, and the O2− and h+ were thought to dominate the photocatalytic process. Based on the experimental and theoretical results, the possible photocatalytic mechanism was proposed.