Electrochemical Conversion of CO2 to Ethyl Formate in Ethanol

Electrochemical reduction of CO2 to valuable chemicals using renewable energy is a promising approach to economically incentivizing lower greenhouse gas emissions. CO2 electroreduction in ethanol is unprecedented despite ethanol being a sustainable and relatively safe solvent. Here, we demonstrate that electrochemical CO2 reduction in acidic ethanol on Pb and Sn cathodes can lead to the production of ethyl formate, a novel and valuable three-carbon ester product. Combining the production of formic acid in these solvents with an in situ acid-catalyzed Fischer esterification reaction leads to sustained ethyl formate production. The effects of pH, anolyte composition, current density, membrane hydration, and supporting electrolyte choice on ethyl formate synthesis were investigated. In particular, durable electrochemical performance was enabled using tetraethylammonium chloride supporting electrolyte in ethanol catholyte with an acidic aqueous anolyte at a selectivity for ethyl formate of 44% faradaic efficiency.