Ce 4f and oxygen vacancy synergistically reinforce Cu-O covalency for efficient CO2 electroreduction to ethylene

Stabilizing the Cu δ+ (1 < δ < 2) valence state during CO 2 reduction reaction (CO 2 RR) process is essential to enhance the C-C coupling and further promote the conversion of CO 2 into value-added C 2+ products. Herein, we propose a new strategy to stabilize the Cu δ+ under the synergistic effect of 4f orbital and oxygen vacancies (O v ) through the construction of Ce doped CuO with enriched O v via symbiotic strategy (CuCeO-O v ). Theoretical calculations and experimental results show the derived gradient orbital coupling O v -[Ce 4f-O 2p-Cu 3d] unit with Ce 4f as electron buffer as well as O v as electron supply station can facilitate the electron itinerancy during CO 2 RR process, which is beneficial to reinforce the Cu-O covalency and inhibit peroxidation of Cu δ+ , thus endowing CuCeO-O v with a highly active (Faradaic efficiency of C 2 H 4 reaches 51% at −1.3 V vs. RHE) and stable bidirectional self-regulating capability (the current density and FE of C 2 H 4 show virtually no attenuation even after 13 h) simultaneously. This work not only gives a profound insight to the synergistic effect of dopants and O v in metal oxides but also provides new guidance to structural design of high-performance insert materials.