Microbial fuel cells operated with iron-chelated air cathodes

The use of non-noble metal-based cathodes can enhance the sustainability of microbial fuel cells (MFCs). We demonstrated that an iron-chelated complex could effectively be used as an aerated catholyte or as an iron-chelated open air cathode to generate current with the use of MFCs. An aerated iron ethylenediaminetetraacetic acid (Fe-EDTA) catholyte generated a maximum current of 34.4 mA and a maximum power density of 22.9 W m⁻³ total anode compartment (TAC). Compared to a MFC with a hexacyanoferrate catholyte, the maximum current was similar but the maximum power was 50% lower. However, no replenishment of the Fe-EDTA catholyte was needed. The creation of an activated carbon cloth open air cathode with Fe-EDTA–polytetrafluoroethylene (PTFE) applied to it increased the maximum power density to 40.3 W m⁻³ TAC and generated a stable current of 12.9 mA (at 300 mV). It was observed that the ohmic loss of an open air cathode MFC was dependent on the type of membrane used. Moreover, increasing the anode electrode thickness of an open air cathode MFC from 1.5 to 7.5 cm, resulted in a lowering of the power and current density.