Fe/Fe₃C nanoparticles in situ-doped with carbon nanofibers embedded in rGO as high-performance anode electrocatalysts of microbial fuel cells

Microbial fuel cells (MFCs) demonstrate significant potential as renewable energy devices due to their ability to harvest electrical energy from wastewater. However, sluggish extracellular electron transfer (EET) efficiency and poor biofilm colonization on the anode interface greatly restrict the power generation of MFCs. Anchoring efficient anode electrocatalysts over the anode surface has been proven to be a powerful strategy to enhance the overall performance of MFCs. Herein, anode electrocatalysts comprising carbon nanofibers in situ-doped with Fe/Fe3C nanoparticles and reduced graphene oxide (rGO/NCNFs@Fe/Fe3C) were fabricated through electrospinning, carbonization, and freeze-drying methods, based on the following considerations: (i) the excellent electrocatalytic properties and biocompatibility of Fe3C; (ii) the formation of abundant reactive sites (such as Fe-N) on the surface of carbon nanofibers induced by the doping of N and Fe elements; (iii) the aerogel structure with a huge specific surface area and excellent electrochemical properties. Therefore, an MFC with an rGO/NCNFs@Fe/Fe3C-modified anode achieved a maximum power density of 2318 mW m(-2) and a maximum output voltage of approximately 0.64 V, which was significantly superior to that of the pristine carbon cloth anode. This work provides a novel strategy to improve biofilm colonization and EET, thus promoting the power generation of MFCs. The aerogel structure composed of NCNFs and rGO is conducive to the colonization and extracellular electron transport of microorganisms.