Upcycling CO 2 into Long Chain Fatty Acids by Decoupled Microbial Electrochemical Systems

Abstract The heavy reliance on fossil fuels results in excessive greenhouse emissions, exacerbating environmental change, and global warming. CO 2 electrocatalysis has been widely studied and the products are limited to C 1‐2 . Herein, we reported the integration of electrocatalysis and microbial catalysis for the synthesis of fatty acids from CO 2 . Here, we compared two decoupled MESs for fatty acid production, electrocatalysis‐purification system (System I), and direct‐electrocatalysis system (System II). Firstly, an upstream electrolysis was used to reduce CO 2 to formate using KHCO 3 and medium as electrolyte, respectively, with carbon nanofiber supported bismuth (Bi@PCF) catalyst. The results indicated that KHCO 3 as electrolyte had higher formate yield and Faraday efficiency than that of medium. Subsequently, a downstream microbial catalysis composed of Cupriavidus species was employed to synthesize fatty acids from formate in System I and System II, respectively. It was demonstrated that System I with the yield of 1.006 mg L −1 was more favorable for the synthesis of fatty acids than System II with the yield of 0.349 mg L −1 . These results suggested that decoupled electrochemical and microbial catalysis were an efficient approach for fixing CO 2 , indicating the great potential of a renewable energy driving artificial photosynthesis.