Rational design of copper-based single-atom alloy catalysts for electrochemical CO2 reduction

Electrochemical CO2-reduction reaction (CO2RR) is a promising way to alleviate energy crisis and excessive carbon emission. The Cu-based electrocatalysts have been considered for CO2RR to generate hydrocarbons and alcohols. However, the application of Cu electrocatalysts has been restricted by a high onset potential for CO2RR and low selectivity. In this study, we have designed a series of Cu-based single-atom alloy catalysts (SAAs), denoted as TM1/Cu (111), by doping isolated 3d-transition metal (TM) atom onto the Cu (111) surface. We theoretically evaluated their stability and investigated the activity and selectivity toward CO2RR. Compared to the pure Cu catalyst, the majority TM1/Cu (111) catalysts are more favorable for hydrogenating CO2 and can efficiently avoid the hydrogen-evolution reaction due to the strong binding of carbonaceous intermediates. Based on the density functional theory calculations, instead of the HCOOH or CO products, the initial hydrogenation of CO2 on SAAs would form the *CO intermediate, which could be further hydrogenated to produce methane. In addition, we have identified the bond angle of adsorbed *CO2 can describe the CO2 activation ability of TM1/Cu (111) and the binding energy of *OH can describe the CO2RR activity of TM1/Cu (111). We speculated that the V/Cu (111) can show the best activity and selectivity for CO2RR among all the 3d-TM-doped TM1/Cu (111). This work could provide a rational guide to the design of new type of single-atom catalysts for efficient CO2RR.