Theoretical study of CO2 electrochemical reduction on Cu(111) and Sn@Cu (111) surface in presence of water

Carbon dioxide (CO2) electrochemical reduction is an important technique for CO2 utilization. Sn-doped Cubased catalysts usually shows good activity for CO2 reduction reaction. However, the effect of Sn-dopant in the presence of water solvent is rarely studied. This is critical because CO2 electrochemical reduction occurs at catalyst/electrolyte interface. In this work, H-shuttling and water-solvated solvent models are considered, and the mechanism of HCOOH and CH3OH production through CO2 reduction on clean and Sn doped Cu(111) surfaces in presence of H2O is systematically investigated by density functional theory calculations. The results show that, in presence of H2O molecule, the rate-limiting step toward CH3OH production is found to be the reduction of CO2 into COOH on both the Cu(111) and Sn@Cu(111) surfaces. However, the addition of Sn lowers the activation barrier of this rate control step, and thus makes Sn@Cu(111) more conductive to the formation of CH3OH. Also, the calculations also show that Sn doping exhibits no significant effect on the formation of HCOOH. The result provides a deep insight on the Sn doped Cu-based catalyst for CO2 electrochemical reduction reaction.