Designing highly biocompatible electrodes of chitosan modified carbon felt for efficient electro-driven CO2 bio-reduction to methane.

Converting CO₂ into methane by microbial electrosynthesis is one of the promising CO₂ valorization technologies. However, the incompatible interface between electrode and methane-producing archaea is challenging to achieve efficient electron transfer and methane production. This study explores the sustainable production of methane from CO2 in microbial electrosynthesis by using carbon felt electrodes modified with chitosan and magnetite. Extremely thick biofilm was found on chitosan modified electrode surface, which exhibited more than 340-fold improvement of methane production (12.5 L·m-2·d-1) compared to unmodified electrodes. Electrochemical tests were conducted to characterize their bioelectrochemical activities and showed high excellent electron transfer abilities of electroactive biofilm on electrode surface. The microbial community dominated by genera such as Methanosarcina (>80% ratio of archaea) on the modified electrodes, indicating a favorable adaptation to the electrochemical conditions. This study demonstrates that the modification of electrodes with chitosan can enhance CO2 methanation in microbial electrosynthesis, which has important implications for energy sustainability and the reduction of CO2 emissions.