Dual‐Layer Conducting and Redox Polymer Bioanodes for Synergistic Enhancement of Microbial Extracellular Electron Transfer

Microbial electrochemical systems (MESs) offer a sustainable platform for energy conversion and biosensing, but their performance is limited by total low extracellular electron transfer (EET) and insufficient electrode interface engineering. Existing studies tend to improve ether the electrochemically active surface area (EASA) of bioelectrodes by conducting coatings or the bio‐electrochemical interfacial electron transfer by redox mediation, but rarely both. To address this limitation, a functionally integrated bioanode was developed by combing a conductive poly(3,4‐ethylenedioxythiophene) (PEDOT) layer with a ferrocene‐modified linear polyethyleneimine (Fc‐LPEI) redox polymer (RP) on carbon felt. This dual‐layer architecture integrates high conductivity and large EASA with efficient redox mediation. Utilizing Shewanella oneidensis MR‐1, the resulting CF‐PEDOT‐RP electrode achieved a maximum current of 1.8 ± 0.1 mA (720 ± 20 µA cm − 2 ), outperforming electrodes modified with PEDOT alone (224 µA cm − 2 ) or Fc‐LPEI alone (480 µA cm − 2 ), demonstrating clear synergistic enhancement. Electrochemical analysis revealed that PEDOT improves conductivity and promotes bacterial attachment, while Fc‐LPEI facilitates reversible electron transfer at the biointerface. The composite electrode also exhibited improved stability and enabled both bioenergy generation and sensitive biosensing. These results establish a versatile strategy for engineering high‐performance bioelectrodes through functional integration of conductive and redox‐active polymers.