The performance and mechanism of modified activated carbon air cathode by non-stoichiometric nano Fe3O4 in the microbial fuel cell.

Abstract Cathodic catalyst is one of the key materials in microbial fuel cell (MFC). The addition of non-stoichiometric nano Fe 3 O 4 in activated carbon (NSFe 3 O 4 /AC) air cathode was beneficial to boosting the charge transfer of the cathode accompanying with the enhancement of power performance in MFC. The air cathode modified by NSFe 3 O 4 (5%, Wt%) increased the maximum power density by 83.3% from 780 mW/m 2 to 1430 mW/m 2 compared with bare air cathode. The modified cathodes showed enhanced electrochemical properties and appeared the maximum exchange current density of 18.71×10 −4  A/cm 2 for oxygen reduction reaction. The mechanism of oxygen reduction for the NSFe 3 O 4 /AC catalyst was a 4-electron pathway. The oxygen vacancy of the NSFe 3 O 4 played a crucial role in electrochemical catalytic activity. The great catalytic performance made NSFe 3 O 4 have a promising outlook applied in MFC.