Final Report: Rational Design of Anode Surface Chemistry in Microbial Fuel Cells for Improved Exoelectrogen Attachment and Electron Transfer

: The overall goal of this project is to determine how electrode surface chemistry can be rationally designed to decrease resistance and increase power density in microbial fuel cells (MFCs). We now have 9 peer-reviewed journal publications from this project on this topic, with more in preparation. In this project period we applied electrochemical oxidation of activated carbon anodes to demonstrate that increasing roughness, oxygen containing groups, and hydrophilicity all tended to improve anode performance. Novel alkane-thiol self-assembled monolayer (SAM) anodes were also tested to show that more hydrophilic, higher surface energy SAMs (trimethylamine and carboxylic) provided the best performance as anodes. 454 pyrosequencing demonstrated that beta and gamma Proteobacteria were dominant on these anodes. Custom activated carbon cathodes were constructed with varying characteristics to show that cathodes with largest amounts of carbon oxides and larger pores tended to have the best performance. Non-Pt group metals were also evaluated as cathode materials, and it was determined that materials derived from iron salt and aminoantipyrine (Fe-AAPyr) or mebendazole (Fe-MBZ) provided superior or comparable performance to Pt at higher pH values. We also initiated a novel set of experiments evaluating pili, motility, and electron transfer using Shewanella mutants.