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 CO₂ electroreduction (CO₂RR) but encounter insufficient C₂₊ 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 CuO₅ and CuO₆ motifs to boost asymmetric C─C coupling for efficient CO₂-to-C₂₊ conversion. For the proof-of-concept catalyst of La_0.8Ba_0.2CuO_3-δ, their ordered, corner-sharing CuO₅ pyramids and CuO₆ octahedra feature localized charge density redistribution, creating abundant asymmetric Cu─Cu dual sites with distinct electronic structures and also strengthening Cu─O covalency. In CO₂RR (in both alkaline and acidic media), La_0.8Ba_0.2CuO_3-δ greatly promotes C₂₊ formation while producing negligible CH₄, showing a Faradaic efficiency ratio (C₂₊ to CH₄) of up to 180. Moreover, La_0.8Ba_0.2CuO_3-δ, achieving a remarkable C₂₊ 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 CuO₅─CuO₆ 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.