Carbon-Based Materials as Electrodes for Biofuels Electrosynthesis

Abstract

Society is struggling to establish a low-emission economy. In this context, bio-electrosynthesis of biofuels is a promising prospect. A microbial electrolysis cell (MEC) can produce methane, enhancing the naturally occurring methanogenic phenomena by applying a low voltage to bio-electrodes. These bio-electrodes rely on biocompatibility and architectural features to maximize the extracellular electron transfer (EET) between a microbial consortium and the power supply; hence, its effectiveness is highly dependent on biofilm development. Porous carbonaceous materials are capable to interact with metallic electrodes and microbes due to their similitude to natural habitats. Felts also provide an open three-dimensional structure and fiber interconnectivity while maintaining good electronic conductivity that allows for efficient microbial waste disposal. The material and manufacturing procedure is key for the final properties of the electrode. Graphite and carbon felt are the most common materials. Graphite felts are obtained after graphitization of carbon felts. An enhanced wettability can be achieved via plasma, thermal, or chemical treatment, while metallic nanoparticles, graphene, and carbon nanofibers are used to enhance their conductivity. However, when low cost is relevant, a simpler treatment may be more suitable. Therefore, the best method will depend on the application and purpose of the electrode.