Catalytic response of microbial biofilms grown under fixed anode potentials depends on electrochemical cell configuration

• Microbial biofilms show different catalytic response at different anode potentials.
• Membrane-less bioelectrochemical cell poised at +0.2 V vs. Ag/AgCl showed maximum current density of >5000 mA/m2.
• Membrane separated bioelectrochemical cell poised at −0.3 V vs. Ag/AgCl showed current density of 4000 mA/m2.
• Preliminary microbial analysis shows differences in both configurations.

In microbial electrochemical cells the anode potential can vary over a wide range, which alters the thermodynamic energy available for bacterial-electrode electron exchange (termed electroactive bacteria). We investigated how anode potential affected the microbial catalytic response of the electroactive biofilm. Microbial biofilms induced to grow on graphite electrodes by application of a fixed applied anode potential in membrane-separated and membrane-less electrochemical cells show differences in electrocatalytic response. Maximum current density is obtained using +0.2 V vs. Ag/AgCl to induce biofilm growth in membrane-less cells, in contrast to a maximum achieved at lower applied potentials in a membrane-separated electrochemical cell configuration. This insight into differences in optimal applied potentials based on cell configuration can play an important role in selection of parameters required for microbial fuel cells and bio-electrochemical systems.

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