Electrochemical CO 2 Reduction to Ethanol with Copper-Based Catalysts

Electrochemical CO 2 reduction presents a sustainable route to storage of intermittent renewable energy. Ethanol is an important target product, which is used as a fuel additive and as a chemical feedstock. However, electrochemical ethanol production is challenging, as it involves the transfer of multiple electrons and protons alongside C–C bond formation. To date, the most commonly employed and effective catalysts are copper-based materials. This Review presents and categorizes the most efficient and selective Cu-based electrocatalysts, which are divided into three main groups: oxide-derived copper, bimetallics, and copper- and nitrogen-doped carbon materials. Only a few other specific examples fall outside this classification. The catalytic performance of these materials for ethanol production in aqueous conditions is discussed in terms of current density, overpotential, and faradaic efficiency. A critical evaluation of the factors that contribute to high performance is provided to aid the design of more efficient catalysts for selective ethanol formation.