Coupling Electrochemical CO ₂ Reduction With Ethanol Oxidation for Acetate Production in a Dual‐Electrolyzer System

ABSTRACT Bioethanol production from biomass is suggested as a strategy for greener fuel production. However, an equimolar amount of CO 2 is released during fermentation, making the process less efficient. Utilizing this released CO 2 directly in an electrolyzer can further reduce carbon emissions, ultimately reaching a CO 2 ‐negative carbon balance. We coupled the electrochemical CO 2 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.