Selectively electrolyzing CO2 to ethylene by a Cu–Cu2O/rGO catalyst derived from copper hydroxide nanostrands/graphene oxide nanosheets†

Abstract

Electrolyzing CO₂ into ethylene (C₂H₄) is a promising strategy for CO₂ utilization and carbon neutrality since C₂H₄ is an important industrial feedstock. However, selectively converting CO₂ into C₂H₄ via the CO₂ electro-reduction reaction (CO₂ ERR) is still a great challenge. Herein, Cu–Cu₂O nanoparticles anchored on reduced graphene oxide nanosheets (Cu–Cu₂O/rGO) were prepared from copper hydroxide nanostrands (CHNs) and graphene oxide (GO) nanosheets via in situ electrochemical reduction. Cu–Cu₂O nanoparticles with diameter less than 10 nm were formed on the surface of rGO nanosheets. After assembling the Cu–Cu₂O/rGO catalyst into a flow cell, it demonstrated high Faraday efficiencies (FEs) of 55.4%, 37.6%, and 6.7% for C₂H₄, C₂H₆, and H₂, respectively, and a total 93% FE for C₂ at −1.3 V vs. the standard hydrogen electrode (SHE). Moreover, its FE was 68.2% for C₂H₄, 10.2% for C₂H₆, and 20.5% for H₂ at −1.4 (vs. SHE). Besides, no liquid carbon product was detected. This high selectivity is attributed to the synergistic effect arising from the small diameter of Cu–Cu₂O NPs with the combination of Cu⁰–Cu⁺ and rGO nanosheets, which promotes the activation of CO₂ molecules, facilitates C–C coupling, and enhances stability. This may provide a facile way for designing an efficient catalyst for selectively electrolyzing CO₂ into valuable C₂ chemicals.