(469d) CO2 Reduction on the Nickel Surface

Nickel is a typical catalyst for carbon dioxide reforming. In this study, we investigate the mechanism of reducing CO₂ on the Ni(110) surface in the presence of the subsurface or impinging hydrogen using spin-polarized periodic density functional theory and ab initio molecular dynamics simulations. In the case of the subsurface H atoms, they act as both spectator species and reactants of the reactions and hence provide the extra energy for overcoming the reaction barriers, in which the major contribution comes from the energetics of subsurface H emerging to the surface as a reactant. While in the case of the impinging hydrogen, the simulation results show direct theoretical evidence for both associative and redox mechanisms in the reaction of atomic hydrogen with CO₂. Because H₂ is dissociatively chemisorbed on Ni(110) with nearly unit probability, the mechanisms we find are also relevant to the reverse water-gas shift reaction (H₂ with adsorbed CO₂). Furthermore, we provide the first real-time demonstration of both Eley-Rideal and hot atom mechanisms when H impinges on adsorbed CO₂.