Bismuth MOF-derived BiOBr/Bi24O31Br10 heterojunctions with enhanced visible-light photocatalytic performance

Abstract

In this work, a hierarchical BiOBr/Bi₂₄O₃₁Br₁₀ heterojunction is prepared for the first time from a bismuth MOF (Bi-BTC) by a facile bromination–annealing route. Since cetyltrimethylammonium bromide (CTAB) is used as the Br element source, the heterojunction constructed of BiOBr and Bi₂₄O₃₁Br₁₀ nanosheets maintains the rod-like morphology of the original MOF. In photocatalytic degradation tests, the BiOBr/Bi₂₄O₃₁Br₁₀ heterojunction exhibits much higher photocatalytic activity than pure Bi₂O₃, and the heterojunctions annealed at 450 °C show the best photocatalytic activity among samples prepared at various temperatures. The heterojunction also shows good pH adaptability, good reusability, and structural stability for RhB degradation, and the TOC results and full UV-vis spectra confirm its good mineralization performance under visible-light irradiation. Based on the photo-electrochemical characterization and free radical tests, a photocatalytic enhancement mechanism over the heterojunction and different photocatalytic reactions in the presence of photo-induced h⁺, ˙O₂⁻ and ¹O₂ are reasonably proposed.