Photocatalytic CO₂ reduction and MO degradation performance of BiOBr enhanced by double anion defects

Photocatalytic CO2 conversion and photocatalytic degradation technologies are effective approaches for energy transformation and environmental cleanup, whose efficiency hinges on the catalytic material. In this work, a series of BiOBrx with varying Bi3+ to Br− ratio were synthesized at room temperature using bismuth nitrate and tetrapropylammonium bromide as precursors. When Bi3+:Br− ratio is 6:5, the flower-like BiOBr5 with dual anionic vacancies (VOs and VBrs) was produced, which exhibited optimal photocatalytic performance. Without using any sacrificial agent, BiOBr5 achieved a CO molar turnover frequency of 8.46 μmol·g−1·h−1, which is 1.92 times higher than that of BiOBr6, demonstrating good selectivity and stability. Furthermore, BiOBr5 reach degradation rates 47.8% and 94.5% towards 20 mg·L−1 methyl orange (MO) aqueous solution under visible light and full-spectrum illumination, respectively. , The excellent photocatalytic properties of BiOBr5 is attributed to VOs and VBrs, which expanded the light absorption range and improved the separation efficiency and transfer rates of charge carriers. The enhancement of dual anionic vacancies in the design and preparation of BiOBr photocatalytic materials provides insights for photocatalysis development.