How Does the Choice of Anode Material Influence Electrical Performance? A Comparison of Two Microbial Fuel Cell Model Organisms

The influence of the anode material on the electrical performance of the two microbial fuel cell model organisms Geobacter sulfurreducens and Shewanella oneidensis is investigated. High-surface-area activated carbon and low-surface-area graphite felt are compared in terms of polarization curves under quasi-steady-state conditions. Unexpectedly, G. sulfurreducens exhibits similar current densities up to 700Acm(-2) independent of the anode material. This is approximate to 50% higher than steady-state values reported previously. The negligible influence of electrode material on the electrical performance of G. sulfurreducens is attributed to the fact that it performs only direct electron transfer, but forms thick biofilms. In contrast, S. oneidensis, relying mainly on mediated electron transfer, apparently makes better use of high-surface-area activated carbon and achieves higher current densities compared to graphite felt. This underlines the importance of tailoring anode materials according to the used organisms.