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Electrocatalytic CO 2 Reduction Coupled to Formate Fermentation: An Electro‐Bio Cascade Approach in Biocompatible Electrolytes

Year: 2025

Type: article

Abstract: ABSTRACT Integration of electrochemical CO 2 reduction with microbial fermentation enables conversion of CO 2 into valuable chemicals but poses challenges at the electrolysis‐fermentation interface. The electrolyte must ensure efficient CO 2 reduction while remaining compatible with microbial growth. We investigated various electrolytes for coupling CO 2 electroreduction to formate with formate fermentation by Methylorubrum extorquens TK 0001. Electrolyte performance was evaluated by formate production and microbial growth. A phosphate‐based buffer demonstrated the best overall compatibility. Optimal microbial growth occurred at 0.1 mol L −1 KPi, with tolerance of up to 111 mmol L −1 formate. Continuous CO 2 electrolysis in 1.0 mol L −1 KPi produced 2.0 mol L −1 formate in 48 h. Formate fermentation with M. extorquens showed biomass yield of 107 mg CDW g formate −1 and a growth rate of 0.10 h −1 . These results highlight the crucial role of buffer composition and concentration in balancing efficient CO 2 electroreduction with stable fermentation. Optimizing this electrochemical–biological interface enables direct utilization of CO 2 ‐derived formate as a substrate for sustainable microbial production, offering a promising scalable route for industrial biotechnology.

Source: Chemistry - A European Journal

DOI: 10.1002/chem.202502658