Stable Surface-Anchored Cu Nanocubes for CO₂ Electroreduction to Ethylene

Abstract

The electrochemical carbon dioxide reduction reaction (CO2RR) is a promising solution to the current environmental and energy issues. Cu is the only metal catalyst able to convert CO2 into high-value-added hydrocarbons. However, Cu catalysts tend to degrade with the decrease in the hydrocarbon selectivity under operation conditions. Herein, we monitored the morphological evolution of Cu nanocatalysts and correlated with changes in the selectivity of hydrocarbon products during electrochemical CO2 reduction. Initial Cu nanospheres quickly reconstructed into nanocubes within 1 h of CO2 electrolysis and then gradually turned into even smaller irregular nanoparticles. Interestingly, the above unstable Cu nanocube offered the maximum ethylene selectivity. We successfully stabilized these Cu nanocubes using a 2D graphene surface doped with nitrogen to achieve high ethylene selectivity over 24 h. Our X-ray photoelectron spectroscopy (XPS) and density-functional theory (DFT) investigations show that the strong interaction between Cu and pyridinic nitrogen on the 2D graphene surface plays a key role in stabilizing Cu nanocubes.