Plasmon‐induced reduction of bromate with Au–Ag–AgI/Al 2 O 3 under visible‐light irradiation

BACKGROUND The plasmon‐induced photocatalytic reduction of bromate (BrO 3 – ) was investigated in visible‐light irradiated Au–Ag–AgI/Al 2 O 3 suspension. The BrO 3 – reduction process was studied in detail . RESULTS The catalyst was found to be highly effective for the reduction of BrO 3 – from pH 3 to 6. An enhancement of the electrical interaction between BrO 3 – and the positively charged surface of the photocatalyst favored adsorption and reduction of BrO 3 – . Organic compounds such as ethanol could react as sacrificial electron donors with excited holes (h + ) on the metal nanoparticles (NPs) to accelerate electron transfer, inhibiting the release of metal ions and the recombination of h + and electrons, hence promoting photocatalytic reduction of BrO 3 – . Electron quenching and cyclic voltammetry studies under a variety of experimental conditions verified that BrO 3 – trapped conduction band electrons of AgI from the excited metal NPs were reduced, competing with O 2 . CONCLUSION The photocatalyst Au–Ag–AgI/Al 2 O 3 exhibited particularly good reduction of BrO 3 – under visible‐light irradiation. The BrO 3 – reduction was highly favored at acidic condition due to the greater adsorption of BrO 3 – onto the catalyst. This finding indicates that this visible‐light‐driven catalyst could be applied to the reduction of some oxidative pollutants or even simultaneous removal of both oxidative and reductive pollutants. © 2013 Society of Chemical Industry