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

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 CeO2 surfaces, focusing on the oxidation of CO and H2. Utilizing density functional theory (DFT) calculations, we report that Cu adatoms bind favorably on different CeO2 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 due to the less populated d-band, while H2 shows a by ~1 eV weaker adsorption. CO oxidation is energetically more favorable than H2 oxidation on the Cu/CeO2(111) surface. The rate-controlling steps for the Mars-van Krevelen oxidation involve the formation of a bent CO2- intermediate for CO and H2O for H2. 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/CeO2, for CO adsorption and oxidation in heterogeneous catalysis.