Double-Chamber Microbial Fuel Cell with a Non-Platinum-Group Metal Fe-N-C Cathode Catalyst

Non-Pt-group metal (non-PGM) materials based on transition metal-nitrogen-carbon (M-N-C) and derived from iron salt and aminoantipyrine (Fe-AAPyr) of mebendazole (Fe-MBZ) were studied for the first time as cathode catalysts in double-chamber microbial fuel cells (DCMFCs). The pH value of the cathode chamber was varied from 6 to 11 to elucidate the activity of those catalysts in acidic to basic conditions. The Fe-AAPyr- and Fe-MBZ-based cathodes were compared to a Pt-based cathode used as a baseline. Pt cathodes performed better at pH 6-7.5 and had similar performances at pH 9 and a substantially lower performance at pH 11 at which Fe-AAPyr and Fe-MBZ demonstrated their best electrocatalytic activity. The power density achieved with Pt constantly decreased from 94-99 μW cm^-2 at pH 6 to 55-57 μW cm^-2 at pH 11. In contrast, the power densities of DCMFs using Fe-AAPyr and Fe-MBZ were 61-68 μW cm^-2 at pH 6, decreased to 51-58 μW cm^-2 at pH 7.5, increased to 65-75 μW cm^-2 at pH 9, and the highest power density was achieved at pH 11 (68-80 μW cm^-2). Non-PGM cathode catalysts can be manufactured at the fraction of the cost of the Pt-based ones. The higher performance and lower cost indicates that non-PGM catalysts may be a viable materials choice in large-scale microbial fuel cells.