BrO3– Bridge Bi2O3/Bi(OH)3 Heterojunction with Multiple Charge Transfer Channels for Efficient Photocatalytic Nitrogen Fixation and CO2 Reduction

A BrO3–-modified Bi2O3/Bi(OH)3 heterojunction photocatalyst was in situ fabricated by a facile one-pot method and applied in photocatalytic nitrogen fixation. In comparison with Bi(OH)3, the Bi2O3/Bi(OH)3 heterojunction has a larger specific surface area from the nanoflower-like morphology and an extended visible light absorption range. Of special importance, the proper band gap match between Bi(OH)3 and Bi2O3, the multiple charge transfer channels via the BrO3– bridge, and the oriented electron migration in the type-II heterojunction mechanism make a stronger charge separation efficiency. Therefore, the BiO/BiHO-3 sample presented the highest photocatalytic nitrogen reduction performance with an ammonia production rate of 45.28 μmol g–1 h–1, which was 10 times higher than that of Bi(OH)3. Photogenerated cavities are consumed during H2O oxidation to produce O2 and H2O2. However, the O2 production was small, and the H2O2 yield was about 78.5 μmol g–1 h–1. For CO2 reduction, the CO production rate was 52.86 μmol g–1 h–1, which was 1.6 and 1.9 times those of Bi(OH)3 and Bi2O3. This work provides useful guidance for the design and synthesis of efficient catalysts for photocatalytic N2 fixation.