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Katuri, KP,Rengaraj, S,Kavanagh, P,O'Flaherty, V,Leech, D
2012
May
Langmuir
Charge Transport through Geobacter sulfurreducens Biofilms Grown on Graphite Rods
Published
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Optional Fields
MICROBIAL FUEL-CELLS C-TYPE CYTOCHROME ANODIC ELECTRON-TRANSFER FE(III) OXIDE REDUCTION ELECTRICITY-GENERATION ELECTROCHEMICAL CHARACTERIZATION ENERGY GENOME VOLTAMMETRY EXPRESSION
28
7904
7913
Biofilms of the electroactive bacterium Geobacter sulfurreducens were induced to grow on graphite-rod electrodes under a potential of 0 V (vs Ag/AgCl) in the presence of acetate as an electron donor. Increased anodic currents for bioelectrocatalytic oxidation of acetate were obtained when the electrodes were incubated for longer periods with periodic electron-donor feeding. The maximum current density for acetate oxidation increased 2.8-fold, and the biofilm thickness increased by 4.25-fold, over a time period of 83-147 h. Cyclic voltammetry in the presence of acetate supports a model of heterogeneous electron transfer, one electron at time, from biofilm to electrode through a dominant redox species centered at -0.41 V vs Ag/AgCl. Voltammetry performed under nonturnover conditions provided an estimate of the surface coverage of the redox species of 25 nmol/cm(2). This value was used to estimate a redox species concentration of 7.3 mM within the 34-mu m-thick biofilm and a charge-transport diffusion coefficient of 3.6 X 10(-7) cm(2)/s. This value of diffusion coefficient is greater than that observed in traditional thin-film voltammetric studies with redox polymer films containing much higher surface concentrations of redox species and might be associated with proton transport to ensure electroneutrality within the biofilm upon electrolysis.
DOI 10.1021/la2047036
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