Carbon support curvature modulates CO₂ activation on molybdenum carbide clusters

Density functional theory (DFT) is employed to investigate CO₂ adsorption and activation on a representative Mo₆C₅ cluster supported on both flat and curved graphene, with particular focus on the effects of support curvature. In the free-standing cluster, a locally metal-rich triangular Mo₃ site exhibits the strongest CO₂ binding. However, this highly reactive site anchors to the carbon support, thus becoming inaccessible to adsorbates, simultaneously conferring enhanced CO₂ activation capability to the remaining stoichiometric Mo-C sites. Support curvature provides an additional lever: MoC_y clusters in convex regions further strengthen CO₂ adsorption, whereas those in concave regions thermodynamically and kinetically favor CO₂ dissociation, thereby facilitating subsequent conversion steps. These findings reveal the dual structural and electronic roles of carbon supports, paving the way for designing more tailor-made MoC_y/C-based catalysts for CO₂ utilization.