Asymmetric, Corner‐Sharing CuO₅ and CuO₆ Motifs in Cu‐Based Metallic Perovskite Oxides Boosting Asymmetric C─C Coupling for CO₂ Electroreduction to C₂₊

Abstract Cu‐based perovskite oxides feature significant potential for CO 2 electroreduction (CO 2 RR) but encounter insufficient C 2+ selectivity primarily due to the inherent symmetric charge distribution at Cu sites hindering asymmetric C─C coupling. Here we report a unique type of Cu‐based metallic perovskite oxides with asymmetric, corner‐sharing CuO 5 and CuO 6 motifs to boost asymmetric C─C coupling for efficient CO 2 ‐to‐C 2+ conversion. For the proof‐of‐concept catalyst of La 0.8 Ba 0.2 CuO 3‐δ , their ordered, corner‐sharing CuO 5 pyramids and CuO 6 octahedra feature localized charge density redistribution, creating abundant asymmetric Cu─Cu dual sites with distinct electronic structures and also strengthening Cu─O covalency. In CO 2 RR (in both alkaline and acidic media), La 0.8 Ba 0.2 CuO 3‐δ greatly promotes C 2+ formation while producing negligible CH 4 , showing a Faradaic efficiency ratio (C 2+ to CH 4 ) of up to 180. Moreover, La 0.8 Ba 0.2 CuO 3‐δ , achieving a remarkable C 2+ Faradaic efficiency of 85.0% at 400 mA cm −2 , together with well‐boosted stability, outperforms previously reported Cu‐based‐perovskite catalysts. Our experiments and theoretical calculations attribute the superb performance mainly to the following factors: the asymmetric CuO 5 ─CuO 6 sites promoting differentiated *CO adsorption/hydrogenation to favor asymmetric *CO─*CHO coupling; the strengthened Cu─O covalency stabilizing the Cu sites. Extending this strategy to two additional pairs of Cu‐based perovskite oxides generates similarly successful results.