Gas-Mediated Co Single-Atom and Co0 Synergy Driving CO2 Hydrogenation to Methanol over Co/In2O3 Catalysts

In₂O₃ modified by Co can significantly promote the catalytic activity for CO₂ hydrogenation to methanol, but there still remains a huge challenge in identifying the active sites due to variable Co phases driven by complex local environments. In this work, we find that reduction pretreatment induces Co₃O₄ to become highly dispersed, and the reduction-reaction environment leads to the formation of isolated Co sites and Co⁰ derived from a few aggregates, as confirmed by multiple surface techniques. A semiquantitative relationship between catalytic activity and surface structure clearly indicates that the synergistic sites integrating isolated Co sites and metallic Co enhance the adsorption and activation of H₂ and CO₂, thereby promoting methanol formation. The presented results imply that this reaction goes through the formate route via Co/In₂O₃. Moreover, the catalyst is stable in redox environments, and especially Co single atoms could help stabilize the surface active structure and achieve high catalytic performance.