Coupling Electrochemical CO2 Reduction with Ethanol Oxidation for Acetate Production in a Dual-Electrolyzer System

Bioethanol production from biomass is suggested as a strategy for greener fuel production. However, an equimolar amount of CO2 is released during fermentation, making the process less efficient. Utilizing this released CO2 directly in an electrolyzer can further reduce carbon emissions, ultimately reaching a CO2-negative carbon balance. We coupled the electrochemical CO2 reduction reaction with ethanol oxidation as the anode reaction for acetate production. A nickel foam-supported cobalt selenium catalyst, which is highly active for ethanol oxidation, reached a Faradaic efficiency of nearly 96 % towards acetate. A high production rate of 95.2 µmol cm-2 min-1 at a current density of 1 A cm-2 in a model flow-through electrolyzer was achieved. For coupled electrolysis at 100 mA cm-2, we achieved 99% and 95% FE for CO and acetate at the cathode and anode, respectively. Furthermore, using a defect-Cu-triazole catalyst on the gas diffusion cathode, we show a tandem cell system coupled with ethanol oxidation in both reactors for selective acetate production. This proof-of-concept approach can be further developed for a greener approach to bioethanol and acetate production.