Boosting CO₂ Electroreduction to C₂H₄ via Unconventional Hybridization: High-Order Ce⁴⁺ 4f and O 2p Interaction in Ce-Cu₂O for Stabilizing Cu⁺

Efficientconversion of carbon dioxide (CO2) into value-addedmaterials and feedstocks, powered by renewable electricity, presentsa promising strategy to reduce greenhouse gas emissions and closethe anthropogenic carbon loop. Recently, there has been intense interestin Cu2O-based catalysts for the CO2 reductionreaction (CO2RR), owing to their capabilities in enhancingC-C coupling. However, the electrochemical instability of Cu+ in Cu2O leads to its inevitable reduction to Cu-0, resulting in poor selectivity for C2+ products.Herein, we propose an unconventional and feasible strategy for stabilizingCu(+) through the construction of a Ce4+ 4f-O2p-Cu+ 3d network structure in Ce-Cu2O. Experimental results and theoretical calculations confirm thatthe unconventional orbital hybridization near E (f) based on the high-order Ce4+ 4f and 2p can moreeffectively inhibit the leaching of lattice oxygen, thereby stabilizingCu(+) in Ce-Cu2O, compared with traditional d-phybridization. Compared to pure Cu2O, the Ce-Cu2O catalyst increased the ratio of C2H4/CO by1.69-fold during the CO2RR at -1.3 V. Furthermore, in situ and ex situ spectroscopic techniqueswere utilized to track the oxidation valency of copper under CO2RR conditions with time resolution, identifying the well-maintainedCu(+) species in the Ce-Cu2O catalyst. This worknot only presents an avenue to CO2RR catalyst design involvingthe high-order 4f and 2p orbital hybridization but also provides deepinsights into the metal-oxidation-state-dependent selectivity of catalysts.