Efficient hypochlorous acid (HClO) production via photoelectrochemical solar energy conversion using a BiVO4-based photoanode

Abstract

A BiVO₄/WO₃/FTO (FTO: fluorine doped tin oxide coated glass) multilayer photoelectrode was found to be suitable for photoelectrochemical oxidative hypochlorous acid (HClO) production from chloride ions (Cl⁻). HClO was efficiently produced in the electrolyte solution by irradiating the BiVO₄/WO₃/FTO photoanode with simulated solar light. It was expected that Cl⁻ would be oxidized to chlorine (Cl₂) by the photogenerated holes on the BiVO₄, and then converted to HClO via the disproportionation reaction in an aqueous electrolyte solution. For the first 100 s, the current efficiency for HClO production was 97%, indicating that the photogenerated hole oxidized Cl⁻ with high selectivity in preference to H₂O. Moreover, the BiVO₄/WO₃/FTO multilayer photoanode enabled us to achieve significant diminution of the external bias required for HClO production under solar light irradiation.