Effects of substrate and metabolite crossover on the cathodic oxygen reduction reaction in microbial fuel cells: Platinum vs. iron(II) phthalocyanine based electrodes

Crossover processes between anode and cathode compartment are important factors that limit the efficiency and performance of fuel cells. This applies not only to chemical but also to biological fuel cells like microbial fuel cells. Whereas effects of an oxygen crossover from the cathode to the anode compartment of microbial fuel cells have already been qualitatively described, the effects of a crossover of organic matter from the anode compartment to the cathode have not yet been studied. In this communication the influence of typical MFC substrates and metabolites on the cathodic oxygen reduction reaction (ORR) at platinum and at pyrolysed iron(II) phthalocyanine (pyr-FePc) based electrodes is studied. It is demonstrated that the performance of platinum is substantially diminished in the presence of these compounds, whereas the ORR performance at pyr-FePc remains largely unaffected. The presence of sulphide, however, inhibited the electrocatalysis at both materials.