Insights on the Catalytic Active Site for CO2 Reduction on Copper-based Catalyst: A DFT study

Cu oxide and Cu are widely used catalyst in CO2 reduction reaction (CO2RR) for methanol (CH3OH) production. However, due to the complexity of the oxidation states on catalyst surfaces, the active sites of Cu-based catalysts for CO2RR are still unclear. In this study, density functional theory (DFT) calculations were performed to investigate the active sites for CO2RR reduction into CH3OH on Cu (111) and CuO (111) surface. The most favored adsorption sites and reaction energetics involved in CO2 activation and sequent CO hydrogenation steps for CH3OH formation were determined. It has been found that, for CO2 reduction, the CO2_*COOH*_*CO* pathway prefers to occur on both Cu (111) and CuO (111) surfaces. More importantly, the analysis reveals that, compared with Cu (111) and clean CuO (111), sequent CO hydrogenation into CH3OH is promoted by the H precovered CuO (111), on which the surface H is set on Cu site (HCu). That is, in CO2RR, the catalytic active sites for CH3OH production are the H-covered Cu sites on CuO (111) surface. These new insights on the catalytic active sites for CH3OH production on Cu-based catalyst would potentially guide the design of efficient CO2RR catalysts.