Boosting power output in microbial fuel cell with sulfur-doped MXene/polypyrrole hydrogel anode for enhanced extracellular electron transfer process

Microbial fuel cell (MFC) has been regarded as a promising green and clean electricity generation device. The anode plays a crucial role in the electricity generation process within the MFC. This study employed a hydrothermal method for the doping of sulfur onto MXene nanosheets to alleviate the stacking, followed by an in situ polymerization process to fabricate sufur-doped MXene/polypyrrole (S-MXene/PPy) composite hydrogel on carbon felt (CF). The MFC constructed with this anode exhibited the highest power density of 8.05 W m-3 and a maximum output voltage of 646 mV, higher than that of MXene/PPy (623 mV, 6.03 W m-3), PPy (594 mV, 4.91 W m-3), and unmodified CF (574 mV, 4.05 W m-3). This improved performance can be attributed to the reduction of charge transfer resistance in the material while improving the bacteria affinity, leading to enhanced extracellular electron transfer (EET) efficiency. High-throughput sequencing indicates that the excellent biocompatibility significantly promotes the attachment and growth of electroactive microorganisms (Geobacter, 45.34%) on the S-MXene/PPy anode. This study demonstrates that S-MXene/PPy hydrogel has good potential as an anode from the perspective of MFC electricity generation and microbial analysis.