Pd‐Induced Cu Site Differentiation in Pd 1 Cu/Ag–N–C Catalyst Enables Asymmetric CO─CHO Coupling for Efficient CO 2 ‐to‐C 2 H 4 Conversion

Abstract Electrochemical CO 2 reduction to ethylene (C 2 H 4 ) presents a pivotal strategy for industrial decarbonization and carbon valorization but is persistently hindered by the intrinsic high kinetic barrier for symmetric *CO─*CO coupling on conventional Cu catalysts. To surmount this fundamental challenge, we synthesized a tandem Pd 1 Cu/Ag–N–C catalyst that achieves site differentiation of the surface Cu. The Pd 1 atom induces electronic heterogeneity by creating two electronically distinct Cu sites. The Pd‐proximal sites promote *CO protonation to *CHO by leveraging Pd assisted H 2 O dissociation, and Pd‐distal sites stabilize *CO. This synergistic division unlocks a highly efficient asymmetric C─CHO coupling pathway. Operando spectroscopy and DFT calculations confirm that the engineered pathway lowers the critical C─C coupling barrier by ∼50%. The Pd 1 Cu/Ag–N–C catalyst delivers a peak C 2 H 4 Faradaic efficiency of 78.8% (±2.5%) with a partial current density of 441 mA cm −2 at ‐0.97 V versus RHE in a flow cell, while maintaining excellent operational stability. This work validates asymmetric CO─CHO coupling as a superior route for C 2 H 4 electrosynthesis by introducing a generalizable design paradigm of precisely steering reaction pathways on multi‐carbon electrocatalysts.