Fuel cell power generation from marine sediments: Investigation of cathode materials

Background: Marine sediment microbial fuel cells (MFC) utilise oxidisable carbon compounds and other components present in sediments on ocean floors and similar environments to produce power in conjunction with, principally, oxygen reduction at the cathode in the overlying water. The aim of the work was to investigate a range of cathode materials for sediment MFC, to achieve relatively high levels of power. Results: Cell potential and power density performance data are reported for sediment MFC using cathodes of: carbon sponge, cloth and paper, graphite and reticulated vitreous carbon (RVC), Co and Fe-Co tetramethoxyphenyl porphyrin (FeCoTMPP) and platinised carbon and titanium. The anode was graphite cloth. After a period of stabilisation, open circuit voltages of 700 mV and maximum power densities of 62 mW m^-2 were obtained, using FeCoTMPP. Relatively low cost carbon cathodes gave power densities of around 30 mW m^-2. Conclusions: The study has shown that low level power can be produced from marine sediments using MFC without separators between the fuel and seawater containing dissolved oxygen. Cathode performance was an important factor determining the power output. Electrocatalyst at the cathode improved performance: FeCoTMMP gave power densities of 60 mW m^-2 which was twice that achieved with the best un-modified carbon.