Engineering asymmetric CC coupling via Ce‐promoted water activation at CuOCe interfaces for CO 2 electroreduction

Electrochemical CO 2 reduction to multi‐carbon products is hindered by Cu + instability and sluggish CC coupling kinetics. We construct CuOCe interfaces that synergistically stabilize Cu + and modulate hydrogenation pathways. The Ce 4+ /Ce 3+ redox pair preserves Cu + under cathodic bias via Cu 3d‐O 2p‐Ce 4f hybridization. Critically, Ce sites lower the H 2 O dissociation barrier from 0.67 to 0.43 eV, increasing *H supply. This *H flux promotes *CO hydrogenation to *COH, redirecting coupling from *CO dimerization to an asymmetric CO–COH route toward *OCCOH. The optimized catalyst achieves a C 2+ Faradaic efficiency of 80.17% at 600 mA cm −2 with stability exceeding 185 h. Our findings establish that modulating water dissociation kinetics at oxide–oxide interfaces provides a generalizable strategy for steering CC coupling, shifting the design paradigm from maximizing *CO coverage to managing *H supply.