Cation-Deficiency-Dependent CO 2 Electroreduction over Copper-Based Ruddlesden-Popper Perovskite Oxides

We report an effective strategy to enhance CO electroreduction (CER) properties of Cu-based Ruddlesden-Popper (RP) perovskite oxides by engineering their A-site cation deficiencies. With La CuO (L C, x=0, 0.1, 0.2, and 0.3) as proof-of-concept catalysts, we demonstrate that their CER activity and selectivity (to C or CH ) show either a volcano-type or an inverted volcano-type dependence on the x values, with the extreme point at x=0.1. Among them, at -1.4 V, the L C delivers the optimal activity (51.3 mA cm ) and selectivity (41.5 %) for C , comparable to or better than those of most reported Cu-based oxides, while the L C exhibits the best activity (25.1 mA cm ) and selectivity (22.1 %) for CH . Such optimized CER properties could be ascribed to the favorable merits brought by the cation-deficiency-induced oxygen vacancies and/or CuO/RP hybrids, including the facilitated adsorption/activation of key reaction species and thus the manipulated reaction pathways.