P.S. Jana, K. Katuri, P. Kavanagh, A. Kumar, D. Leech
Phys. Chem. Chem. Phys. 16, pp. 9039-9046, (2014)
Harnessing, and understanding the mechanisms of growth and activity of,
biofilms of electroactive bacteria (EAB) on solid electrodes is of
increasing interest, for application to microbial fuel and electrolysis
cells. Microbial electrochemical cell technology can be used to generate
electricity, or higher value chemicals, from organic waste. The
capability of biofilms of electroactive bacteria to transfer electrons
to solid anodes is a key feature of this emerging technology, yet the
electron transfer mechanism is not fully characterized as yet. Acetate
oxidation current generated from biofilms of an EAB, Geobacter sulfurreducens,
on graphite electrodes as a function of time does not correlate with
film thickness. Values of film thickness, and the number and local
concentration of electrically connected redox sites within Geobacter sulfurreducens
biofilms as well as a charge transport diffusion co-efficient for the
biofilm can be estimated from non-turnover voltammetry. The thicker
biofilms, of 50 ± 9 μm, display higher charge transport diffusion
co-efficient than that in thinner films, as increased film porosity of
these films improves ion transport, required to maintain
electro-neutrality upon electrolysis.