The major hurdle to the success of microbial fuel cell (MFC) is electron transfer from microbe to the electrode. Compared to conventional fuel cells electricity generation in MFCs has been very low. Even this current density has been achieved, in most cases, with the help of redox mediators. Our research objective is to improve the performance of mediator-less MFCs.

A new design was proposed to reduce the internal resistance and to improve the catalyst utilization (Figure 1). Escherichia coli K12 with glucose substrate, and buffer solution was used at anode, and air at the cathode. Catalyst layers were prepared by incorporating solubilized Nafion® in the catalyst layer to improve proton conductivity.

An initial sharp drop in voltage due to poor activation was observed during the cell polarization (Figure 2). A proper method of activation was adopted prior to operation of the cell. MFC performance close to that reported in the literature was obtained with this method (Figure 3). Moreover, carbon containing reaction products of substrates at the anode are found to poison the catalyst surface; this is evident from the gradual drop in performance of the MFC with time.

Our preliminary results have shown further improvement in catalyst utilization and power output by proper design of catalyst interface. A dynamic hydrogen electrode to characterize the anode catalyst, and the role of micro-organism in reducing overpotential at the anode will be demonstrated. Moreover, improved performance will be reported by using Pt-X catalyst that is more active towards carbon containing species.