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

It is a promising green technology to reduce CO₂ to CH₄ by using renewable solar energy driving photo-thermal catalysis route. However, the efficiency of photo-thermal catalytic CO2 methanation remained to be improved, and the mechanism of this reaction still required further investigation. In this paper, a Ru/Mg-CeO₂ catalyst was designed based on the concepts of single atom catalyst and photo-thermal catalysis concept. The catalyst achieved the CH₄ formation rate of 469 mmol·gcat⁻¹·h⁻¹ at 400 °C under photo-thermal conditions with good catalytic stability. Besides, the superiority of the single-atom of Ru, Ru-O-Ce structure and doping of alkaline metals in catalytic process was proved by a series of physicochemical and optical characterization, and electron migration direction from Ce and Mg elements to Ru sites through Ru-O-Ce and Ru-O-Mg path under photo-thermal catalysis was determined by ISI-XPS experiment. Finally, the comprehensive reaction mechanism and reversible dynamic structural evolution process between Ru-O-Ce and Ru-O_v-Ce structures were investigated by in situ DRIFTs experiments, and the source of the excellent performance and structure-function relationship of the catalyst was explored, which provided the theoretical and practical basis for the development of catalyst and industrial application of the reaction.