Selective Photocatalytic Aerobic Oxidation of Methane to Methyl Hydroperoxide by ZnO-Loaded Single-Atomic Ruthenium Oxide Catalyst

Photooxidation of CH4 to value-added chemicals with high selectivity offers a promising pathway to drive the rational utilization of natural gas resources with renewable energy under mild conditions. However, owing to the poor chemoselectivity of reactive oxygen radical formation and consecutive side reactions of primary products, the synthesis of peroxide directly from CH4 oxidation remains challenging. Here, we report single-atom ruthenium oxide-doped ZnO as a highly selective photocatalyst for the aerobic oxidation of CH4 to CH3OOH. Under optimal conditions, the CH3OOH formation rate over Ru1Ox/ZnO reaches 321 μmol gcat–1 h–1 with a high selectivity of 90.9% under simulated solar irradiation. Mechanistic studies reveal that the selective generation of •OOH radicals via oxygen reduction and the ability to prevent secondary side reactions of CH3OOH are the main advantages of Ru1Ox/ZnO, accounting for the remarkable selectivity of CH3OOH from CH4. The single-atom Ru oxide/ZnO catalyst also exhibits remarkable chemoselectivity to alkyl hydroperoxide in the photocatalytic oxidation of low paraffins, which provides a solution to prepare value-added peroxide from a single-step oxidation of hydrocarbon substrates.