Effective solar-light-driven photocatalytic production of hypobromous acid on film-like photocatalyst sheets

Abstract

Photocatalytic production of hypobromous acid (HBrO) by oxidation of bromide (Br⁻) under simulated solar light was successfully achieved over visible-light active photocatalysts. Among all photocatalysts, the platinum (Pt) cocatalyst-loaded tungsten oxide (WO₃) powder showed the highest HBrO production after 30 min of photoirradiation by simulated solar light (approximately 8.7 μM) for the photocatalytic oxidation of Br⁻ with oxygen reduction. Moreover, the formation rate of HBrO reached 80 μM h⁻¹ by fixing the bismuth vanadate (BiVO₄)/WO₃ photocatalyst and Pt cocatalyst on the fluorine-doped tin oxide (FTO) conductive substrate as a photocatalyst sheet. The apparent quantum yield of the HBrO production over the Pt–BiVO₄/WO₃/FTO photocatalyst sheet was more than 11% at 400 nm. The close contact between the BiVO₄ and WO₃ particles played an important role in improving the photocatalytic activity for the production of HBrO, which could be ascribed to the highly effective separation of photogenerated electrons and holes between BiVO₄ and WO₃.