Detailed Analyses of Light Intensity Dependence to Uncover Multielectron Oxygen-Reduction Mechanism by Platinum-Loaded Tungsten(VI) Oxide

Elucidation of the mechanism of multielectron transfer reactions, such as photocatalytic water oxidation and oxygen reduction, is essential for achieving high efficiency in the utilization of sustainable solar energy. Herein, we demonstrate that photocatalytic oxygen reduction on platinum-loaded tungsten(VI) oxide (Pt/WO3) photocatalyst proceeds predominantly by two-electron transfer pathway under conventional light-intensity conditions. Light intensity-dependence analyses of the acetic acid decomposition reaction revealed the role of the Pt co-catalyst in enhancing overall quantum efficiency. We also report for the first time that the reaction can be initiated even on bare WO3, in addition to Pt, under extremely high light-intensity conditions.