Ultrathin nanoflake-assembled hierarchical BiOBr microflower with highly exposed {001} facets for efficient photocatalytic degradation of gaseous ortho-dichlorobenzene

A series of BiOBr catalysts with different microstructures were synthesized by tuning the solvothermal conditions. Assisted by the surface photovoltage, transient photovoltage and time-resolved photoluminescence techniques, the photoexcited charge carriers separation and transfer dynamics were comparatively investigated. The results indicated that the hierarchical BiOBr microflower (BiOBr MF) consisting of well-organized ultrathin nanoflakes were most efficient in promoting charge carrier separation and migration, resulting from the nearly 100 % {001} facets exposed with more oxygen defects. Furthermore, the photocatalytic performance was estimated through the degradation of gaseous ortho-dichlorobenzene (o-DCB) under visible light irradiation, and the BiOBr MF exhibited superior photoactivity. The enhanced mechanism underlying the charge transfer was disclosed by the energy band structures and the reactive oxygen species which were examined by room temperature electron spin resonance. In addition, the catalytic oxidation process of o-DCB over the BiOBr MF and the corresponding surface intermediates was revealed by in situ FTIR spectroscopy.