Evaluation of Microbial Fuel Cells with Graphite Plus MnO₂and MoS₂Paints as Oxygen Reduction Cathode Catalyst

For the improvement of microbial fuel cell (MFC) performance in real wastewater it is necessary to implement catalysts on the cathode. Potential electrochemical catalysts for the MFC have to be widely available and should be low cost materials. Graphite, MnO 2 and MoS 2 fulfill the requirements and were evaluated in this work. These materials were prepared by dispersion of MnO 2 and/or MoS 2 and graphite in a solution of celluloid using butanone as solvent. Four MFCs with an active area of 225 cm 2 were connected in series with the wastewater supply. Their individual maximum output power densities were evaluated in relation to time. The results showed that MFC without catalyst reached a power density of only 40 mW/m 2 , while the best performance of MFC with graphite plus MnO 2 coating (10:1) was higher than 100 mW/m 2 . Comparing with graphite plus MnO 2 coating, the graphite plus MoS 2 paint shows a lower power density but much higher long-term stability than graphite plus MnO 2 coating. The scaling up of MFC with catalyst on the cathode is also studied in this research. Four MFCs with dimension of 980 cm 2 were constructed and connected in series, whose anodes have two sides for enlargement of reaction surface area.