Rich Cu+-OV-Ce3+ motifs enable highly efficient electrochemical CO2 reduction to C2H4 over CuCe-based oxide catalysts

The electrochemical CO 2 reduction reaction (ECO 2 RR) offers a route to convert CO 2 into value-added chemicals such as ethylene (C 2 H 4 ). However, this process is constrained by the low content and poor stability of Cu + species, which severely limits the selectivity for C 2 products. To address this issue, we designed CuCe-based oxide catalysts, tuning both the morphology of CeO 2 supports and the Cu loading to maximize the abundance of interfacial Cu + -O V -Ce 3+ motifs and thereby enhance both the content and stability of Cu + species. The resulting optimized catalyst, 10CuCe-S (CeO 2 nanospheres with 10 wt% Cu loading), achieves a C 2 H 4 Faradaic efficiency of 40.2% and a partial current density of 6.63 mA cm −2 at −1.2 V vs. RHE. Structural analyses confirm that the optimal support nanosphere structure and 10 wt% Cu loading give the richest Cu + -O V -Ce 3+ interfacial configuration, leading to a high Cu + density of 69.2% in the 10CuCe-S catalyst, which also exhibits excellent Cu + stability. In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) reveals key intermediates (*COOH, *CO, *CHO, *COH) along with rich *COCO species on 10CuCe-S, indicating that abundant Cu + sites facilitate C-C coupling toward C 2 H 4 formation.