Low-cost Fe–N–C catalyst derived from Fe (III)-chitosan hydrogel to enhance power production in microbial fuel cells

A low cost Fe–N–C catalyst on an activated carbon (AC) support was synthesized from inexpensive ferric chloride and chitosan precursors to enhance power production by microbial fuel cells (MFCs). The direct pyrolysis of preformed Fe(III)-chitosan hydrogel as a supporting scaffold created a porous structure on AC with a uniform distribution of Fe active sites. A maximum power density of 2.4 ± 0.1 W m⁻² was obtained in MFCs using Fe–N–C/AC catalyst, which was 33% higher than the control MFCs using a plain AC catalyst (1.8 ± 0.03 W m⁻²). The Fe–N–C/AC catalyst was closer to the more efficient four electron transfer pathway for the oxygen reduction reaction (ORR) than the plain AC or chitosan-modified AC. The adoption of chitosan as the N-containing precursor and ferric chloride for the Fe–N–C synthesis added only 6% more in material costs in cathode fabrication, but produced a 33% increase in the maximum power density. This increased power makes the use of this cathode material both economically viable and a sustainable approach to enhance power production in MFCs given the low cost and wide availability of chitosan.