Controllable Synthesis of Bi_xO_yBr_z/TiO₂ Heterojunctions with Excellent Visible‐Light‐Driven Photocatalytic Activities for Phenol

Abstract

BixOyBrz/TiO2 composites have been synthesized by hydrothermal method, with TiO2 nanoparticles being employed as substrate. During the process of hydrothermal reaction, both temperature and pH have been utilized to effectively regulate the Bi/Br atomic ratio of BixOyBrz/TiO2 composites. In essence, the competitive reaction between OH− and Br− in the solution is the key factor to form BixOyBrz with different Bi/Br atomic ratios. Under visible light, the prepared Bi4O5Br2/TiO2 heterojunction demonstrates higher photocatalytic activity than other BixOyBrz/TiO2 composites for phenol and Rh B. The removal rate of phenol with Bi4O5Br2/TiO2 heterojunction is up to 92.1% after irradiation for 75 min. The excellent photocatalytic activities of Bi4O5Br2/TiO2 heterojunction are mainly attributed to its optimized microstructure and the matching band energy structure, whereby TiO2 nanoparticles with ≈10 nm diameter uniformly arranged on ≈10.2 nm thick Bi4O5Br2 nanosheets. Moreover, the heterojunction structure promotes the separation of photo‐generated electrons and holes in Bi4O5Br2/TiO2, while and h+ are the main active species during its photocatalytic processes.