Operando X‐Ray Absorption Spectroscopy Reveals Dynamic Interfacial Metal–Metal Coordination Governing CO ₂ Reduction Selectivity in PdAg Alloys

ABSTRACT

Achieving high selectivity towards single carbon products in electrochemical CO ₂ reduction requires precise control over intermediate binding energies, a challenge that monometallic catalysts cannot address due to inherent electronic structure limitations. Bimetallic catalyst offers a strategic solution through synergetic electronic effects that decouple these correlations, enabling independent optimization of CO ₂ activation and CO desorption, critical steps for selective single‐carbon production. Herein, we demonstrate a Pd _x Ag _1‐x electrocatalyst system that achieved a CO selectivity of 91% at −1.1 V versus RHE with an optimized composition. Operando X‐ray absorption spectroscopy reveals that Ag as the active site, undergoes partial oxidation to Ag ⁺ under reaction conditions, donating electron density to Pd sites, while EXAFS analysis establishes composition–dependent metal–metal (M–M) bonding as the critical selectivity determinant. These findings provide a quantitative design framework for rational composition engineering of next‐generation bimetallic CO ₂ reduction catalysts based on active site coordination dynamics.