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

Abstract

Efficient conversion of carbon dioxide (CO 2 ) into value-added materials and feedstocks, powered by renewable electricity, presents a promising strategy to reduce greenhouse gas emissions and close the anthropogenic carbon loop. Recently, there has been intense interest in Cu 2 O-based catalysts for the CO 2 reduction reaction (CO 2 RR), owing to their capabilities in enhancing C–C coupling. However, the electrochemical instability of Cu + in Cu 2 O leads to its inevitable reduction to Cu 0, resulting in poor selectivity for C 2+ products. Herein, we propose an unconventional and feasible strategy for stabilizing Cu + through the construction of a Ce 4+ 4f–O 2p–Cu + 3d network structure in Ce-Cu 2 O. Experimental results and theoretical calculations confirm that the unconventional orbital hybridization near E f based on the high-order Ce 4+ 4f and 2p can more effectively inhibit the leaching of lattice oxygen, thereby stabilizing Cu + in Ce-Cu 2 O, compared with traditional d–p hybridization. Compared to pure Cu 2 O, the Ce-Cu 2 O catalyst increased the ratio of C 2 H 4 /CO by 1.69-fold during the CO 2 RR at −1.3 V. Furthermore, in situ and ex situ spectroscopic techniques were utilized to track the oxidation valency of copper under CO 2 RR conditions with time resolution, identifying the well-maintained Cu + species in the Ce-Cu 2 O catalyst. This work not only presents an avenue to CO 2 RR catalyst design involving the high-order 4f and 2p orbital hybridization but also provides deep insights into the metal-oxidation-state-dependent selectivity of catalysts.