Direct synthesis of nanomaterials on carbon microfibre electrode material for superior electrocatalysis in lake sediment microbial fuel cells

The use of novel and inexpensive catalysts as replacements for platinum is desirable. In this study, we demonstrate for the first time that cost-effective metal oxide nanomaterials and the conductive polymer polyaniline (PANI) can be directly chemically synthesized on carbon microfiber electrodes to improve the performance of lake sediment inoculated MFCs. Nanomaterial of MnO2, MnO2/polyaniline (PANI), ZnO/NiO and ZnO/NiO/ PANI attachments were directly chemically synthesized on the carbon material and used as cathode electrodes. The maximum power densities recorded for the different treatments were; MnO2 78.5 mW/m2, MnO2/PANI (Polyaniline) 141.6 mW/m2, ZnO/NiO 67.6 mW/m2, and ZnO/NiO/PANI 129.4 mW/m2. Current and power densities were more than six-fold higher in ZnO/NiO/PANI and MnO2/PANI nanoparticle modified cathodes compared to the control MFCs with no catalyst and more than 2.5 fold higher compared to Pt loaded conventional cathodes. In-excess of 50 -fold reductions in catalyst application costs to obtain a unit amount of power was demonstrated with the novel nanomaterials direct deposition method when compared to traditional catalysts such as Pt. This study demonstrates that nanomaterials-incorporated carbon microfiber cathodes bring about significant enhancements to power densities and may potentially have applications in cost-effective MFCs.