Ru-based catalysts for efficient CO2 methanation: Synergistic catalysis between oxygen vacancies and basic sites

The fundamental insights of the reaction mechanism, especially the synergistic effect between oxygen vacancies and basic sites, are highly promising yet challenging for Ru-based catalysts during carbon dioxide (CO 2 ) methanation. Herein, a series of Ru-based catalysts were employed to study the mechanism of CO 2 methanation. It is found that Ru/CeO 2 catalyst exhibits a much higher CO 2 conversion (86%) and CH 4 selectivity (100%), as well as excellent stability of 30 h due to the existence of abundant oxygen vacancies and weak basic sites. Additionally, the in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations reveal that the formate formation step dominated the hydrogenation route on Ru/CeO 2 catalyst, and the b-HCOO* could be the key intermediate due to b-HCOO* is more easily hydrogenated to methane than m-HCOO*. The systematic study marks the significance of precise tailoring of the synergistic relationship between oxygen vacancies and basic sites for achieving the desired performance in CO 2 methanation.