Distinct reconstruction of aluminum-doped oxide-derived copper enhances the selectivity of C2+ products in CO2 electroreduction

Abstract

The electrochemical carbon dioxide reduction reaction (eCO₂RR) has great potential in addressing environmental and renewable energy storage issues simultaneously. However, highly valuable C₂₊ products are usually obtained at high overpotentials with low Faradaic efficiencies owing to the sluggish kinetics of C–C coupling of the reaction intermediates, especially in neutral electrolytes. Recently, oxide-derived copper (OD-Cu) has attracted significant attention for its high selectivity toward C₂₊ products in the eCO₂RR. While various CuO_x precursors have been reported to influence the reconstruction of CuO_x and product selectivity, CuO_x precursors with new dopants are required to understand the influence of metal dopants. Here, we synthesized Al-doped CuO (CuO_Al) using a metal–organic framework to examine the effect of Al dopants on the catalytic activity of OD-Cu. Interestingly, Al induces reconstruction of CuO_Al, forming nanoflakes, which exhibit a high Faradaic efficiency of 68.4% and a large partial current density of 478.7 mA cm⁻² toward C₂₊ products at −1.08 V versus a reversible hydrogen electrode in a neutral 1 M KHCO₃ electrolyte. Contact angle measurements and lead underpotential deposition revealed that the reconstruction provides CuO_Al with high hydrophobicity and high electrochemically active surface area, respectively. Our findings suggest that the dopant-mediated reconstruction of CuO into OD-Cu can effectively promote activity and selectivity toward C₂₊ products with enhanced structural properties by using small amounts of dopants.