Fast expansion of graphite into superior three-dimensional anode for microbial fuel cells

Bioanodes are core components that affect the performance of microbial fuel cells. In this paper, a superior three-dimensional graphite foam electrode is prepared with rapid gasification of liquid nitrogen and expanding a graphite foil into an expanded graphite foam. With following thermal treatment, thermal treated expanded graphite foam is also prepared. The characterization results indicate that no doping or oxidation occurs during the preparation, which retains a good conductivity and biocompatibility. Microbial fuel cells equipped with expanded graphite foam and thermal treated expanded graphite foam exhibit significantly higher output voltage and power density than graphite foil. Furthermore, cyclic voltammetry and electrochemical impedance spectroscopy are further conducted to investigate the electrochemical performance of different anode materials. Results confirm that the bioelectrochemical activities are enhanced on the fabricated electrodes. Electrochemical active surface area measurement reveals that, other than surface area increase, the graphene-like electrode morphology promotes electron transfer processes. This fast and easy fabrication strategy allows massive production of three-dimensional graphite foam based high performance anodes for microbial fuel cells.