Fine AgPd Nanoalloys Achieving Size and Ensemble Synergy for High‐Efficiency CO2 to CO Electroreduction

Abstract Alloying the active metal with a second metal is an effective way to tailor the adsorption of reaction intermediates through an ensemble effect. Herein, based on theoretical calculations validating that the ensemble sites composed of Ag and Pd atoms could reduce the energy gap for *COOH and *CO intermediates generated during electrocatalytic CO 2 reduction reaction (eCO 2 RR) by either weakening the CO adsorption or enhancing the COOH adsorption, a strategy to produce AgPd alloy nanoparticles with fine sizes for synergizing the ensemble effect and size leverage toward high CO faradaic efficiency in eCO 2 RR is reported. In particular, the AgPd alloy nanoparticles at an optimized Ag/Pd atomic ratio of 35/65 affords a maximum CO faradaic efficiency of 98.9% and a CO partial current density of 5.1 mA cm −2 at the potential of −0.8 V (vs RHE) with satisfactory durability of up to 25 h, outperforming those of most Pd‐based electrocatalysts recently reported and demonstrating great potential for further application in producing CO via eCO 2 RR at ambient conditions.