Wiring microbial biofilms to the electrode by osmium redox polymer for the performance enhancement of microbial fuel cells

An osmium redox polymer, PAA-PVI-[Os(4,4'-dimethyl-2,2'-bipyridine)₂Cl]^+/2+ that has been used in enzymatic fuel cells and microbial sensors, was applied for the first time to the anode of single-chamber microbial fuel cells with the mixed culture inoculum aiming at enhancing performance. Functioning as a molecular wire connecting the biofilm to the anode, power density increased from 1479mWm^-2 without modification to 2355mWm^-2 after modification of the anode. Evidence from cyclic voltammetry showed that the catalytic activity of an anodic biofilm was greatly enhanced in the presence of an osmium redox polymer, indicating that electrons were more efficiently transferred to the anode via co-immobilized osmium complex tethered to wiring polymer chains at the potential range of -0.3V-+0.1V (vs. SCE). The optimum amount of the redox polymer was determined to be 0.163mgcm^-2.