Use of Nanomaterials-Modified Carbon Microfiber Electrode Material for Superior Electrochemical Performance of Lake Sediment Inoculated Microbial Fuel Cells

Abstract

Microbial fuel cells (MFCs) have emerged in recent years as a promising technology for renewable alternative energy and wastewater treatment. MFC technology faces numerous challenges when applied to real-world applications, which is one of the reasons why it has yet to be widely used or commercialized despite its discovery many decades ago. The cathodic overpotential of oxygen reduction reaction (ORR) at MFC cathodebased carbon is a barrier to the widespread adoption of the technology. The performance of MFCs is primarily limited by the cathode. In general, cathode performance can be improved in two ways: by using a catalyst to lower activation energy or by increasing the specific surface area of the cathode material. When used as a catalyst, precious metals such as platinum catalysts reduce overpotential but increase the cost. The use of novel and inexpensive catalysts increases ORR rates, as does the use of non-catalyzed threedimensional carbon in cathode fabrication. The custom-made woven carbon material used for constructing the electrodes, known as carbon microfiber material (CMM), was sourced from Carbon Energy WT in Taiwan. Nanomaterials-modification of these CMM electrodes was used to improve the performance of lake sediment inoculated MFCs. To improve the ORR performance of the carbon electrode through pretreatment, a variety of nanomaterial pretreatment methods were used. KOH, HNO3, MnO2, ZnO/NiO, MnO2/PANI (Polyaniline), and ZnO/NiO/PANI treatments were applied to the CMM and used as cathode electrodes; the performance was compared by plotting powercurrent plots and polarization plots. The maximum power densities for KOH, HNO3, MnO2, MnO2/PANI (Polyaniline), ZnO/NiO, and ZnO/NiO/PANI treatments were 51.71 mW/m2, 71.40 mW/m2, 78.54 mW/m2, 141.64 mW/m2, 67.15 mW/m2 and 129.44 mW/m2 respectively. The outcome of this study demonstrates that the nanomaterials incorporated in carbon microfiber cathodes bring about significant enhancements to power densities, without the usage of noble metal catalyst materials such as platinum.