Theoretical investigation of electrochemical reduction mechanism of CO2 on the Cu(1 1 1), Sn@Cu(1 1 1) and Sn(2 1 1) surfaces

Abstract The electrochemical reduction of CO2 is one of the important technologies for the effective utilization of CO2, and it is also a key step to produce value-added products. In the present study, density functional theory (DFT) is applied to study the reduction mechanism of CO2 to formic acid (HCOOH) and methanol (CH3OH) on the Cu(1 1 1), Sn@Cu(1 1 1) and Sn(2 1 1) catalysts. The adsorption structures of all possible intermediates are determined. It is found that for the HCOOH pathway, the rate-limiting step form the reduction of CO2 to form HCOO on the Cu(1 1 1) and Sn@Cu(1 1 1) surface is transformed to the reduction of HCOO forming HCOOH on the Sn(2 1 1) surface. The activity of three catalyst models towards HCOOH production follows: Sn@Cu(1 1 1) > Sn(2 1 1) > Cu(1 1 1). For the CH3OH pathway, the potential rate-limiting step on the Cu(1 1 1), Sn@Cu(1 1 1) and Sn(2 1 1) surfaces is the formation of COOH via CO2. The activity of three catalyst models towards CH3OH production follows: Sn@Cu(1 1 1) > Cu(1 1 1) > Sn(2 1 1). The results demonstrate that the doping of Sn onto Cu surface may be a potential strategy for the development of efficient CO2 electrocatalyst.