Oxygen Vacancy Bridged Cu–Ce Pairs Boost CO ₂ Electroreduction to C ₂ H ₄ via Accelerating *H Supply and Asymmetric C–C Coupling

Regulating competitive reaction pathways to enhance the selectivity of C2H4 production in electrochemical CO2 reduction reactions is crucial yet remains challenging, primarily due to the limited understanding of the active sites. In this study, we propose oxygen vacancy bridged Cu–Ce pairs to construct an adjustable atomic interface, which enables a Faradaic efficiency of C2H4 as high as 55.6% and stability for 60 h at 300 mA cm–2. Advanced characterizations revealed that the introduction of Ce causes local lattice distortion, breaking the original symmetric coordination structure and promoting the formation of oxygen vacancies. In situ infrared spectroscopy combined with density functional theory calculations show that the redox ion pairs of synergistic interactions of Ce species and oxygen vacancies can accelerate the *CO protonation through facilitating water dissociation, reduce the energy barrier of asymmetric *CO–*CHO coupling, and improve the Faradaic efficiency of electrocatalytic CO2 reduction to C2H4.