Efficient photo-thermal catalytic CO2 methanation and dynamic structural evolution over Ru/Mg-CeO2 single-atom catalyst

•Atomically dispersed Ru/Mg-CeO2 catalyst was prepared and possessed excellent catalytic performance for photo-thermal catalytic CO2 methanation reaction.•The photo-electron excitation/migration path and the surface structure changes induced by light were systematically characterized by operando experiments.•All potential micro-reaction steps and light intensification steps were determined by in situ DRIFTs experiments.•The reversible dynamic structural evolution between Ru-O-Ce structure and Ru-Ov-Ce structure could be induced by light.