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.