Pd-Decorated Cu 2 O-Ag Catalyst Promoting CO 2 Electroreduction to C 2 H 4 by Optimizing CO Intermediate Adsorption and Hydrogenation.

Electrocatalytic CO 2 reduction reaction (CO 2 RR) to high value-added products, such as ethylene (C 2 H 4 ), 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 C 2 H 4 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 H 2 O activation ability hinders the hydrogenation of intermediates. To break through the above bottleneck, herein, palladium (Pd) was introduced into Cu 2 O-Ag, a typical conventional tandem catalyst, to construct a Cu 2 O-Pd-Ag ternary catalyst. Extensive experiment and density functional theory calculation prove that Pd can efficiently stabilize the *CO intermediate and promote the H 2 O activation, which contributes to the C-C coupling and intermediate hydrogenation, the key steps in the conversion of CO 2 to C 2 H 4 . Beneficial to the efficient synergy of Cu 2 O, Pd, and Ag, the optimal Cu 2 O-Pd-Ag ternary catalyst achieves CO 2 RR toward C 2 H 4 with a faradaic efficiency of 63.2% at -1.2 V RHE , which is higher than that achieved by Cu 2 O-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 CO 2 RR electrocatalyst.