Mechanistic Insights into CO and H₂ Oxidation on Cu/CeO₂ Single Atom Catalysts: A Computational Investigation

Abstract

Single atom catalysts (SACs) have attracted significant interest due to their unique properties and potential for enhancing catalytic performance in various chemical reactions. In this study, we atomistically explore adsorption properties and catalytic performance of single Cu atoms anchored at low-index CeO<inf>2</inf> surfaces, focusing on the oxidation of CO and H<inf>2</inf>. Utilizing density functional theory (DFT) calculations, we report that Cu adatoms bind favorably on different CeO<inf>2</inf> surfaces, following a stability order of (100) > (110) > (111). The charge transfer from a single adsorbed Cu atom to Ce leads to the reduction of Ce⁴⁺ to Ce³⁺ and the oxidation of Cu⁰ to Cu⁺. This strengthens molecular bonds at Cu sites, particularly for CO, while H<inf>2</inf> shows a by ~ 1 eV weaker adsorption. CO oxidation is energetically more favorable than H<inf>2</inf> oxidation on the Cu/CeO<inf>2</inf>(111) surface. The rate-controlling steps for the Mars–van Krevelen mechanism involve the formation of a bent CO<inf>2</inf> intermediate for CO and H<inf>2</inf>O for H<inf>2</inf>. The lattice oxygen atom at the interface plays a key role for both oxidation processes. Our findings highlight the potential of single atom catalyst, Cu/CeO<inf>2</inf>, for selective CO adsorption and its subsequent oxidation in heterogeneous catalysis.