Bio-cathode materials evaluation in microbial fuel cells: A comparison of graphite felt, carbon paper and stainless steel mesh materials

The choice of the cathode material is crucial for every bio-cathode microbial fuel cell (MFC) setup. The commonly used biocathode materials, Graphite felt (GF), carbon paper (CP) and stainless steel mesh (SSM) were compared and evaluated in terms of current density, power density, and polarization. The maximum current density and power density of the MFC with GF-biocathode achieved 350 mA m−2 and 109.5 mW m−2, which were higher than that of the MFC with CP-biocathode (210 mA m−2 and 32.7 mW m−2) and the MFC with SSM-biocathode (18 mA m−2 and 3.1 mW m−2). The polarization indicated that the biocathode was the limiting factor for the three MFC reactors. Moreover, cyclic voltammetry (CV) showed that the microorganisms on the biocathode played a major role in oxygen reduction reaction (ORR) for GF- and CP-biocathode but SSM-biocathode. Electrochemical impedance spectroscopy suggested that GF biocathode performed better catalytic activity toward ORR than that of CP- and SSM-biocathode, also supported by CV test. Additionally, the MFC with GF-biocathode had the highest Coulombic Efficiency. The results of this study demonstrated GF was the most suitable biocathode for MFCs application among the three types of materials when using anaerobic sludge as inoculums.

► Systematical comparison on the biocathode materials was studied in MFCs.
► The electrochemical capability of cathodic biofilms was characterized by CV.
► The electrochemical impedance behavior of bio-cathodes was characterized by EIS.
► Graphite felt was the most suitable biocathode for MFCs.
► Biocathode was the main limiting factor in MFCs.