Identification of the active sites for CO2 methanation over Re/TiO2 catalysts

CO2 methanation on heterogeneous catalysts holds great significance in achieving the net-zero emission target. However, understanding the atomic-scale relationship between reactivity and active site has been a subject of debate. The study investigated CO2 methanation reaction catalyzed by Re/TiO2 catalysts and identified the active site distribution and its relationship with reactivity. The low-coordinated edge sites of Re nanoparticle were found to be the active sites where CO2 dissociates into CO via a carbide pathway and subsequently hydrogenates to form methane. Furthermore, the study revealed that the size of the Re nanoparticles influences the distribution of active edge sites and affects the reactivity and stability of the CO intermediate. This intermediate is the rate-determining step in the CO2 methanation reaction. Controlling the size and structure of Re nanoparticles can, therefore, enhance the activity and efficiency of CO2 methanation reaction. The identification of these active sites and the insights gained from this study have significant implications for the mechanistic understanding and optimization of CO2 methanation over Re/TiO2 catalysts. It provides a basis for designing more effective catalysts to facilitate the conversion of CO2 to methane, thereby contributing to the goal of achieving net-zero emissions.