Synthesis and application of graphene-based nanomaterials for microbial fuel cells

Microbial fuel cells (MFCs) have become a sustainable alternative way to generate electricity and treat organic matter in wastewater simultaneously. One of the challenges is to develop anode electrode materials in order to improve the efficiency of removal of contaminants from biomass waste. High surface area, high conductivity, biocompatibility, cost effectiveness, and high mechanical stability are essential parameters of anode material for enhancing its performance. While one of the main challenges with cathode electrode is the development of the efficiency and catalytic stability for the oxygen reduction reaction (ORR), because this reaction has a sluggish kinetics that causes loss of potential. Oxygen has been widely used as an electron acceptor in the cathode due to its high standard redox potential, sustainability, and feasibility. Carbon-based materials, such as graphene and carbon nanotubes, have been used as alternative catalysts because they can be modified with other materials to enhance the ORR. Metal oxides with reverse spinel structure as magnetite and other magnetic materials with a nonstoichiometric structure can create defects causing oxygen vacancies, have been studied as electrocatalysts in MFCs. They offer good stability and economically compared to platinum (Pt); catalyst commonly used in ORR. Therefore, graphene oxide-metal oxide-based material composites improve MFC performance. Both types of electrodes have a significant role in the MFC in term of functionality.