Activated carbon nanofiber anodes for microbial fuel cells

This investigation considers the use of activated carbon nanofiber nonwoven (ACNFN) as a novel anode for microbial fuel cells (MFCs). ACNFN has an ultra-thin, porous interconnected structure with high bioaccessible surface area. Reduced distances from the free surface to the interior maximize use of the available surface area and this, combined with high macroporosity ensures superior performance by decreasing transport limitations. ACNFN was fabricated by pyrolysis of electrospun polyacrylonitrile and subsequent steam activation. Extensive characterization, including surface morphology, material chemistry, surface area, mechanical strength and biofilm adhesion was performed to validate the use of the material as an MFC anode. Preliminary tests in a single chamber MFC showed current densities of 2715 A/m3 which is about 10% greater than the highest maximum obtained so far. Further, this was achieved with a conductivity of only a fifth of that of the corresponding material. The bio-electrochemical performance of ACNFN was also compared to that of commonly-used anodes, carbon cloth and granular activated carbon. Such anode architecture will greatly help mitigate low power density issues which are one of the main factors limiting widespread adoption of MFCs.