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.