Highly Selective CO₂ Electroreduction to Multi-Carbon Alcohols via Amine Modified Copper Nanoparticles at Acidic Conditions

Electroreduction of CO₂ into multi-carbon (C2+) products (e.g. C2+ alcohols) offers a promising way for CO₂ utilization. Use of strong alkaline electrolytes is favorable to producing C2+ products. However, CO₂ can react with hydroxide to form carbonate/bicarbonate, which results in low carbon utilization efficiency and poor stability. Using acidic electrolyte is an efficient way to solve the problems, but it is a challenge to achieve high selectivity of C2+ products. Here we report that the amine modified copper nanoparticles exhibit high selectivity of C2+ products and carbon utilization at acidic condition. The Faradaic efficiency (FE) of C2+ products reach up to 81.8 % at acidic media (pH=2) with a total current density of 410 mA cm⁻² over n-butylamine modified Cu. Especially the FE of C2+ alcohols is 52.6 %, which is higher than those reported for CO₂ electroreduction at acidic condition. In addition, the single-pass carbon efficiency towards C2+ production reach up to 60 %. Detailed studies demonstrate that the amine molecule on the surface of Cu cannot only enhance the formation, adsorption and coverage of *CO, but also provide a hydrophobic environment, which result in the high selectivity of C2+ alcohols at acidic condition.