Cu₂O Nano-Homojunction for High-Efficiency Electrocatalytic CO₂-to-Ethylene Conversion

The efficient electrochemical CO₂ 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 CO₂ by constructing a Cu₂O nano-homojunction, which is composed of Cu₂O nanocubes in size of ≈100 nm and the surface-adhered Cu₂O 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 CO₂-to-ethylene conversion was investigated by in situ experiments and theoretical calculations. The results reveal that such a catalyst is efficient in adsorbing CO₂, stabilizing the key intermediate ^*CO, and facilitating both the ^*CO protonation to form ^*CHO and the subsequent ^*CO-^*CHO coupling for ethylene formation.