Use of nanomaterials-modified carbon microfiber electrode material for superior electrochemical performance in lake sediment inoculated microbial fuel cells

Abstract

High cathodic overpotential of the oxygen reduction reaction (ORR) in MFC carbon-based cathodes is one of the key barriers to the widespread adoption of the technology. Current Pt-based ORR catalysts are expensive. The use of novel and inexpensive catalysts as replacements for platinum is therefore desirable. In this study, nanomaterials were 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. The current and poswer 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. Cyclic voltammetry (CV) and FTIR data and SEM images suggest that the nanoparticle attached carbon material is morphologically, chemically and electrochemically different from the controls with no nanomaterial attachment. The outcome of 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.