Double-defect ZnO aerogel-supported single-atomic ruthenium for selective gas-solid phasephotooxidation of methane to methanol

The selective photooxidation of CH 4 into value-added chemical products under ambient conditions offers a viable pathway for the rational utilization of natural gas resources. However, the direct oxidation of methane to synthesize oxygenates still faces significant challenges due to insufficient chemo-selectivity in active intermediate radical formation and consecutive side reactions of primary products. Rather than introducing multiple metal species to create active sites, we show that controlled defect generation on the substrate offers an effective pathway for catalytic enhancement. Here we developed a ZnO aerogel-supported ruthenium single atom photocatalyst for selective conversion of CH 4 to CH 3 OH. Under ambient conditions, 1Ru/ZnO achieved a methanol production rate of 407 μmol g −1  h −1 with a high selectivity of 91.7%. The observed activity enhancement is principally attributable to two factors: (i) the ZnO aerogel microspheres with abundant dual-defect structures serve as an effective substrate material, offering abundant active sites to facilitate the CH 4 activation process; and (ii) monatomic Ru 4+ sites were employed as efficient active sites for methane adsorption and dehydrogenation; meanwhile the separation of redox sites was optimized to effectively suppress over-oxidation. The integration of aerogels (with abundant defect sites) and supported metal species offers a novel strategy for achieving direct CH 4 oxidation to CH 3 OH‌.