Impact of Increased Surface Area Cathodes Using Nanostructures in Microbial Fuel Cells for Electricity Production

Abstract

Microbial fuel cells (MFCs) are devices that can directly produce electrical energy from renewable feedstocks. However, the low power output of these devices has limited the wider application of this technology. Electrode surface area is an important factor affecting MFC electricity generation. Coating electrodes with nanomaterials has the potential to increase surface area and thus enhance the power output of MFCs. The objectives of this study were to: (1) determine the effects of increasing the surface area on MFC cathodes on energy production, and (2) compare graphite plate and stainless steel mesh as base current collectors. To increase the cathodic surface area, carbon nanotube powder and graphite powder were attached to two types of base current collectors: plain graphite bar stock coated with silver epoxy and stainless steel mesh covered in conductive paint. The graphite powder and carbon nanotube cathodes were created by coating the outside of a graphite bar electrode with silver epoxy and then packing graphite powder or carbon nanotube powder onto the outside of the electrode. The stainless steel cathodes were created by coating the outside of the stainless steel mesh with conductive paint and then packing graphite powder, carbon nanotube powder, or activated carbon onto the surface of the electrode. Results showed that graphite powder produced the greatest increase in peak power density among the coating treatments to graphite bar base current collectors, and that no replicable power enhancements were observed among the stainless steel mesh coatings. This study contributes to improving the MFC power density output, thus expanding the usefulness of MFC technology in a greater breadth of engineering applications.