Enhanced photocatalytic removal of bromate in drinking water by Au/TiO₂ under ultraviolet light

The photo-reduction of bromate (BrO₃ ^-) has attracted much attention due to the carcinogenesis and genotoxicity of BrO₃ ^- in drinking water. In this study, a heterojunction photocatalyst was developed by depositing Au nanoparticles (NPs) onto P25 TiO₂ NPs through a one-pot, solvent-thermal process. Due to the unique properties of Au, the Au NPs deposited on the TiO₂ surface created a Schottky barrier between the metal and the semiconductor, leading to an effective separation of photo-generated charge carriers as the Au nanoparticles served as electron sinks. The Au/TiO₂ photocatalyst demonstrated efficient reduction of BrO₃ ^- under UV light illumination without the need for sacrificial agents. The effect of different Au loading of Au/TiO₂ was systematically investigated for its influence on the generation of electrons and the reduction ability of BrO₃ ^-. The results indicate that the 1% Au/TiO₂ catalyst exhibited a higher concentration of localized electrons, rendering it more effective in BrO₃ ^- removal. The photocatalytic efficiency for BrO₃ ^- reduction decreased upon the addition of K₂S₂O₈ as an electron quencher, suggesting that the primary factor in this photo-reduction process was the availability of electrons. These findings hold promise for the potential application of the Au/TiO₂ catalyst in the removal of BrO₃ ^- from drinking water through photo-reduction.