Selective and Energy Efficient Electrocatalytic CO2-to-Ethanol Conversion through Anion Modulation.

Ethanol, with its high market value and stable global demand, stands out as an attractive product of electrocatalytic CO2 reduction. However, achieving high ethanol selectivity and energy efficiency at industrial current densities remains challenging. In this study, we employed a blended anion modulation strategy to enhance the selectivity and energy efficiency of CO2-to-ethanol conversion. The Cu2(OH)3F pre-catalyst achieved Faradaic efficiencies of 50% and 93% for ethanol and C2+, respectively, at 700 mA cm-2 in a blended electrolyte consisting of 2 M KOH and 1 M KCl. Comprehensive electrochemical tests, combined with in situ characterizations and theoretical analysis, revealed that chloride and hydroxide increased *CO coverage for efficient C─C coupling. Moreover, hydroxide stabilizes the *CHCOH intermediate through hydrogen bonding with the adsorbed hydroxide on the catalyst surface, while Cl synergistically enhances its reactivity by promoting water dissociation toward the ethanol pathway.