Pd-Ag Alloy Electrocatalysts for CO2 Reduction: Composition Tuning to Break the Scaling Relationship.

Constructing solid-solution-alloy electrocatalysts with tunable surface electronic configurations is the key to optimize intermediate bindings and thereby to promote the activity and selectivity of the CO2 reduction reaction (CO2RR). Herein, Pd1-xAgx alloy electrocatalysts are investigated as a platform to uncover the electronic effects on the CO2RR. The optimal Pd0.75Ag0.25/C affords a superior CO Faradaic efficiency of 95.3% at -0.6 V (vs RHE) in 0.5 M KHCO3, performing at a high level among recently reported electrocatalysts. Experimental and theoretical analysis further evidence that varying the composition of Pd1-xAgx alloys can effectively alter the electronic configurations and consequently break the inherent scaling relationship of the binding energy of different intermediates (*COOH and *CO). Among Pd1-xAgx, Pd0.75Ag0.25 gains the obviously weakened *CO and *H bindings but retained well the binding with *COOH, contributing to the facilitated kinetics toward CO product. Elucidating a feasible way to break the scaling relationship and further uncover the underlying mechanism, this work will inspire new design strategies toward active and selective electrocatalysts.