Poly (3,4-ethylenedioxythiophene) promotes direct electron transfer at the interface between Shewanella loihica and the anode in a microbial fuel cell

• Nanoscale porous structure are formed in the bulk of PEDOT by electrodeposition.
• PEDOT modification increases the electrochemical activity of anode.
• PEDOT coating decrease interface electron transfer resistance of anode.
• Porous PEDOT layer cannot improve the affinity of mediator and bacteria.
• Direct electron transfer dominates between PEDOT and bacteria.

Anode modification is an effective method for enhancing extracellular electron transportation and improving the power density of microbial fuel cells (MFCs). In this study, a new conductive polymer called poly (3,4-ethylenedioxythiophene) (PEDOT) is electrochemically polymerized to modify the anode. The surface of the electrochemically polymerized PEDOT layer has a widespread porous structure. Both the anode electrochemical discharge experiment and MFC discharge test demonstrate the improved performance of the PEDOT-modified anode compared with a plain anode. Cyclic voltammetry and electrochemical impedance spectroscopy analyses show that the PEDOT modification increases the availability of redox active sites and reduces the interfacial electron transfer resistance of the anode. Compared with the unmodified anode, the PEDOT anodic modification improves the power density by 43%–140 mW m−2. Possible mechanisms are proposed to help understand the function of the PEDOT-modified anodic layer.