Boosting CO 2 Selective Electroreduction to CH 4 With High Efficiency Over Oxygen‐Riched Cu‐CeO 2 Catalyst by Constructing Heterointerface Built‐in Electric Field

Electrochemical CO 2 reduction reaction (CO 2 RR) to CH 4 offers a sustainable route for carbon neutrality, but it is hindered by sluggish multi‐electron/proton transfer kinetics and poor selectivity. Herein, we rationally design an oxygen‐rich Cu‐CeO 2 catalyst by constructing a heterointerface built‐in electric field (BIEF) for efficient and selective CO 2 ‐to‐CH 4 conversion. The abundant oxygen vacancies induce intense charge redistribution and amplify the directional BIEF driving electron transfer from CeO 2 to Cu, which strengthens CO 2 adsorption, stabilizes *CO intermediates, and lowers the energy barrier of *CO‐to‐*CHO conversion. The optimized Cu/CeO 2 ‐900 catalyst exhibits outstanding CO 2 RR performance, delivering a maximum CH 4 Faradaic efficiency of 73.7% and a large CH 4 partial current density of −307.33 mA cm −2 , together with excellent durability over long‐term continuous operation. A combination of in situ spectroscopic characterizations, electrochemical measurements, and density functional theory calculations validates the oxygen vacancy‐amplified BIEF mechanism and its critical role in boosting CO 2 activation and reaction kinetics. This work establishes a novel defect‐BIEF synergistic strategy to regulate interfacial charge transfer and intermediate adsorption, offering a universal guideline for designing high‐performance electrocatalysts toward selective CO 2 conversion to CH 4 .