Integrating photochemical and photothermal effects for selective oxidative coupling of methane into C2+ hydrocarbons with multiple active sites

The direct photocatalytic oxidation of methane to value-added chemicals has garnered considerable interest in recent years. However, achieving high productivity while maintaining high selectivity at an appreciable methane conversion rate remains a formidable challenge. Here, we present photochemically-triggered and photothermally-enhanced oxidative coupling of methane to multi-carbon C2+ alkanes over an Au and CeO2 nanoparticle-decorated ZnO photocatalyst, which exhibits a record-breaking C2+ production rate of 17,260 μmol g−1 h−1 with ~90% C2+ selectivity under wide-spectrum light irradiation without a secondary source of heating. Comprehensive characterizations and computational studies reveal that CH4 activation is a photochemical reaction initiated by ultraviolet light-excited ZnO, and the introduction of CeO2 substantially enhances the activation of CH4 and O2 due to the cooperative interaction between Au and CeO2. Concurrently, Au nanoparticles capture visible and near-infrared light to generate localized heating, which greatly promotes the subsequent desorption of produced methyl radical for C–C coupling prior to undergoing further undesired overoxidation. Achieving both high activity and selectivity in CH4 photooxidation to C2+ hydrocarbons is challenging. This work shows that integrating photochemical and photothermal effects enhances both, enabling efficient CH4 oxidative coupling to C2+ alkanes.