Electrospinning iron-doped carbon fiber to simultaneously boost both mediating and direct biocatalysis for high-performance microbial fuel cell

The sluggish extracellular electron transfer between the microorganisms and the electrode impedes the broad industrialization of microbial fuel cells (MFCs). Previous works have reported anodes made from iron compounds can improve the output power of MFCs but the underlying mechanism is still unclear. Here, we innovatively prepare a uniform iron ion-mixed carbon precursor to directly electrospinning iron-doped carbon nanofibers (Fe–CNF). The optimized Fe–CNF anode exhibits greatly improved bio-electrocatalytic performance in MFCs, which delivers 8.67 times higher than that of the undoped CNF one. More importantly, results reveal that Fe-doping forms Fe3C in anode, which greatly promotes the adsorption of the mediator flavins for faster mediation electron transfer between substrate and cells, while directly contacting the proteins of cell membrane leads strong direct electron transfer, thereby simultaneously boost both mediation and direct electrochemistry processes. A facile approach to synthesis of high-performance MFCs anode materials for simultaneously boost both mediation and direct electron transfer rate while providing scientific insights in designs of efficient bioelectrochemical systems is furnished by this work.