Gas-induced controllable synthesis of the Cu(100) crystal facet for the selective electroreduction of CO2 to multicarbon products

Abstract

Electrocatalytic CO₂ reduction (ECR) to high value-added chemicals is an excellent method to attenuate the impact of greenhouse effect caused by CO₂. At the same time, multicarbon products (C₂₊) get extensive attention in view of their relatively high energy density and market price. At present, Cu is an important metal electrocatalyst to convert CO₂ into multicarbon products (e.g. ethylene, ethanol, and n-propanol); however, its poor selectivity impedes its practical application. It is well-known that the Cu(100) crystal facet can enhance the selectivity toward multicarbon products among different Cu crystal facets. Herein, the Cu nanoparticles were firstly prepared using the inductive effect of different gases (CO₂, CO, Ar, N₂, and air) during the Cu electrodeposition processes, in which the CO₂-induced Cu catalyst (Cu-CO₂) showed the largest normalized content of the Cu(100) crystal facet and the highest C₂₊ faradaic efficiency of 69% at a current density of 80 mA cm⁻² in ECR. Subsequently, the different CO₂ pressures during the Cu electrodepositions were studied to reveal the optimal CO₂ pressure in the CO₂-induced Cu synthesis for improved Cu(100) content as well as C₂₊ faradaic efficiency. Finally, density functional theory (DFT) calculations confirmed that CO₂ molecules preferred to get adsorbed on the Cu(100) crystal facet, which resulted in not only the presence of dominant Cu(100) during the CO₂-induced Cu synthesis but also the good electrocatalytic performance in ECR.