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.