Microbial fuel cells: Electrode materials

Microbial fuel cell (MFC) is an electrochemical device in which electroactive bacteria are used to produce electricity through substrate (e.g., acetate) oxidation. In MFCs, bacteria achieve respiration using the anode electrode as a terminal electron acceptor via a unique respiratory pathwayextracellular electron transfer. This technology has emerged as a novel sustainable approach to treat wastewater and simultaneously generate bioelectricity. Similar to traditional chemical fuel cells, anode and cathode electrodes are the integral parts of MFCs. For use in MFCs, the electrode materials should ideally be biocompatible, conductive, porous, easily made at low cost, recyclable, and scalable. They should also possess high specific surface area, corrosion resistance, and high mechanical strength. Many electrode materials have been tested for their use and applicability as the anode and/or cathode in MFCs. These include mainly carbon-based (e.g., graphite rod or plate, carbon cloth, carbon paper, carbon felt), metal-based (e.g., stainless steel and platinum), and purposely built advanced materials (e.g., three-dimensional carbon-based and metal-carbon composite materials). The research efforts over the last decade have positioned macroporous and composite carbon or metal-based materials as promising anodes for MFCs. For oxygen reduction reaction at the cathode in MFCs, both abiotic and biological catalysts have been proposed. Designing the low-cost electrode materials without compromising on (bio) electrocatalytic performance is the key to the future development of MFC applications.