Cu ₂ O Nano‐Homojunction for High‐Efficiency Electrocatalytic CO ₂ ‐to‐Ethylene Conversion

Abstract The efficient electrochemical CO 2 reduction into value‐added multi‐carbon products is of great importance and remains challenging. Here, we demonstrate the highly selective, active, and long‐term durable electrocatalytic production of ethylene from CO 2 by constructing a Cu 2 O nano‐homojunction, which is composed of Cu 2 O nanocubes in size of ≈100 nm and the surface‐adhered Cu 2 O nanodots in size of ≈12 nm, as electrocatalyst. The maximum Faradaic efficiency of ethylene can reach 73.7% at −1.4 V versus reversible hydrogen electrode in H‐type cell, with partial current density to ethylene of 38.2 mA cm −2 . Moreover, it can work stably for more than 200 h at 0.31 A cm −2 in membrane electrode assembly. The mechanism for the high selectivity, activity and stability for CO 2 ‐to‐ethylene conversion was investigated by in situ experiments and theoretical calculations. The results reveal that such a catalyst is efficient in adsorbing CO 2 , stabilizing the key intermediate * CO, and facilitating both the * CO protonation to form * CHO and the subsequent * CO‐ * CHO coupling for ethylene formation.