Nanomaterials in microbial fuel cells: from electrode engineering to sustainable energy applications

Abstract Microbial fuel cells (MFCs) are a potential bio electrochemical platform that has the capacity to both treat wastewater and produce energy in a sustainable manner. But their potential usefulness has always been limited by poor power density, slow oxygen removal kinetics, and poor long-term stability. Recent developments on nanomaterials have played a major role in revolutionising MFCs performance through upgrading of electron transfer, augmenting microbial adhesion, catalysing oxygen reduction reactions, and strengthening of membrane stability. Carbon nanostructures, including carbon nanotubes and graphene, are both highly conductive and offer larger surface area to achieve higher anode engineering, whereas transition metal catalysts, including FeNC, MnO 2 , and Co 3 O 4 nanoparticles, are cheaper alternatives to platinum cathodes. Nanomaterial-based membrane, including silica, graphene oxide, TiO 2 , and nanostructured materials, increase proton conductivity and decrease biofouling, increasing operational life. In addition to electricity production, nanomaterial based MFCs have also found use in wastewater treatment, biosensing, biohydrogen co-production, and off-grid energy systems. However, even with these developments, important issues still exist such as high cost of production, environmental issues in terms of toxicity of nanoparticles, and lack of standard evaluation procedures. The priorities of the future also include the development of green nanomaterials, 3D nanostructured electrodes, integration of IoT and AI, and integrating MFCs into circular bioeconomy models. Together, MFCs made possible through nanomaterials provide a sustainable and flexible way towards energy and environmental innovation.