Coordination modulation of iodide at the CuI-Cu2O interface to stabilize Cu+ and promote carbon dioxide-to-ethylene conversion

Electrochemical conversion of CO 2 to value-added chemicals is a promising carbon recycling strategy for mitigating CO 2 emissions from fossil fuels and addressing associated environmental challenges. In copper-based catalysts, Cu + species promote the reduction of CO 2 to multi‑carbon products, such as ethylene (C 2 H 4 ). However, under typical electroreduction, Cu + is prone to reduction to Cu 0 , leading to degradation of catalytic performance and poor stability. Herein, we present an interfacial engineering strategy to design a CuI-Cu 2 O composite catalyst with densely packed Cu 2 O nanoparticles on tetrahedral CuI substrates and self-stabilizing Cu + ability for selective CO 2 electroreduction to C 2 H 4 . Density functional theory (DFT) calculations and spectroscopic characterizations demonstrated that the CuI-Cu 2 O catalyst combined the efficient generation of *CO intermediates by Cu 2 O with the efficient C C coupling functionality of CuI, and the iodide ions within the catalyst autonomously modulated the copper oxidation state to stabilize Cu + , collectively enhancing CO 2 -to-C 2 H 4 selectivity. Consequently, the CuI-Cu 2 O catalyst achieved a C 2 H 4 Faradaic efficiency of 62.98 ± 1.05% along with a high current density of 275.16 mA·cm −2 at −0.97 V vs. the reversible hydrogen electrode (RHE). In the stability test, the CuI-Cu 2 O catalyst operated stably for over 16 h at a current density of approximately 279.95 mA·cm −2 . This study provides a catalyst design strategy that simultaneously enhances *CO supply and C C coupling while autonomously modulating the active Cu + state, offering an effective approach for achieving stable and highly selective CO 2 -to-C 2 H 4 conversion.