Selective Photocatalytic Oxidation of Methane to Methanol by Constructing a Rapid O2 Conversion Pathway over Au–Pd/ZnO

Photocatalytic oxidation of methane to methanol is an attractive process under mild conditions, nevertheless confronting significant challenges in achieving high conversion and selectivity simultaneously. Herein, we propose a strategy for the direct and rapid generation of hydroxyl radicals (•OH) from O2 (O2 → *OOH → •OH) by rational design of Au–Pd/ZnO photocatalyst, skipping water-soluble H2O2 and avoiding H2O2 diffusion. For photocatalytic methane oxidation at ambient temperature, the yield and selectivity of CH3OH over the optimized 1.0% AuPd0.5/ZnO catalyst were as high as 81.0 μmol·h–1 and 88.2%, respectively, exceeding that of most reported systems. The formation of Au–Pd alloys could improve the O2 adsorption and the cleavage of the O–O bond in *OOH, facilitating the efficient direct formation of •OH and increasing the CH3OH yield and selectivity. This work provides some guidance for the delicate design of composite photocatalysts for efficient selective photocatalytic methane oxidation and O2 utilization.