The performance of nano urchin-like NiCo2O4 modified activated carbon as air cathode for microbial fuel cell

• Urchin-like spinel NiCo2O4 was doped in AC air cathode catalyst layer.
• The MPD of treated MFC was 1730 ± 14 mW m−2, 2.28 times higher than the control.
• The ORR and kinetics constant were increased due to a four-electron pathway.
• The mesopores electrode provided more active sites in the catalyst layer.

A nano urchin-like NiCo2O4 has been successfully synthesized via a facile and scalable hydrothermal method. A NiCo2O4 modified active carbon air cathode was designed, optimized and fabricated. The maximum power density of the microbial fuel cell with newly developed cathode is 2.28 time higher than bare active carbon and is comparable to the commercial available Pt/C, reaching 1730 ± 14 mW m−2. The modified active carbon showed remarkable improvement in activity towards the oxygen reduction reaction, which was due to the lower charger transfer, lower activation barrier, and higher exchange current density. Electrochemical evaluation showed a direct four-electron the oxygen reduction reaction on NiCo2O4 modified active carbon, compared to a two-stage process on bare active carbon. The non-precious NiCo2O4 could be considered as a promising alternative to the costly Pt.