Selective photocatalytic oxidation of methane to methanol by enhancing H2O2 utilization over Au-Pd/In2O3

Abstract

Hydrogen peroxide (H2O2) is widely used as an oxidant for photocatalytic oxidation of methane to value-added chemicals under mild conditions, but suffers from low utilization efficiency. Herein, we propose a comprehensive strategy for the proper amount of hydroxyl radicals (•OH) generation from H2O2 by regulating the Pd/Au molar ratios and the total Au-Pd contents loaded on In2O3. For the photocatalytic oxidation of methane at ambient temperature, the yield and selectivity of CH3OH over the optimized 1.0% AuPd0.5/In2O3 catalyst were as high as 2187.0 μmol g−1 h−1 and 94.0% respectively, exceeding most reported literatures. Mechanism investigations revealed that the formation of Au-Pd alloys may contribute to the homolytic cleavage of H2O2 into •OH radicals and improve the selectivity of •OH generation. This work provides some guidance for the delicate design of photocatalysts to manipulate selective H2O2 activation and efficient photocatalytic methane oxidation.