Pd-Decorated Cu2O–Ag Catalyst Promoting CO2 Electroreduction to C2H4 by Optimizing CO Intermediate Adsorption and Hydrogenation

Electrocatalytic CO2 reduction reaction (CO2RR) to high value-added products, such as ethylene (C2H4), offers a promising approach to achieve carbon neutrality. Although recent studies have reported that a tandem catalyst (for example, Cu–Ag systems) exhibits advantage in C2H4 production, its practical application is largely inhibited by the following: (1) a traditional tandem catalyst cannot effectively stabilize the *CO intermediate, resulting in sluggish C–C coupling, and (2) inadequate H2O activation ability hinders the hydrogenation of intermediates. To break through the above bottleneck, herein, palladium (Pd) was introduced into Cu2O–Ag, a typical conventional tandem catalyst, to construct a Cu2O–Pd–Ag ternary catalyst. Extensive experiment and density functional theory calculation prove that Pd can efficiently stabilize the *CO intermediate and promote the H2O activation, which contributes to the C–C coupling and intermediate hydrogenation, the key steps in the conversion of CO2 to C2H4. Beneficial to the efficient synergy of Cu2O, Pd, and Ag, the optimal Cu2O–Pd–Ag ternary catalyst achieves CO2RR toward C2H4 with a faradaic efficiency of 63.2% at −1.2 VRHE, which is higher than that achieved by Cu2O–Ag and most of other reported catalysts. This work is a fruitful exploration of a rare ternary catalyst, providing a new route for constructing an efficient CO2RR electrocatalyst.