Conjugated oligoelectrolyte represses hydrogen oxidation by Geobacter sulfurreducens in microbial electrolysis cells

•Geobacter sulfurreducens was grown in in microbial electrolysis cells.•Addition of a conjugated oligoelectrolyte (COE) completely inhibited H2 oxidation.•DSBN + increased H2 gas recovery 67 ×, and acetate removal 4.4 ×.•Geobacter metallireducens, which cannot oxidize H2, was not affected by COE addition.

A conjugated oligoelectrolyte (COE), which spontaneously aligns within cell membranes, was shown to completely inhibit H2 uptake by Geobacter sulfurreducens in microbial electrolysis cells. Coulombic efficiencies that were 490 ± 95%, due to H2 recycling between the cathode and microorganisms on the anode, were reduced to 86 ± 2% with COE addition. The use of the COE resulted in a 67-fold increase in H2 gas recovery, and a 4.4-fold increase in acetate removal. Current generation, H2 recovery and COD removals by Geobacter metallireducens, which cannot use H2, were unaffected by COE addition. These results show that this COE is an effective H2 uptake inhibitor, and that it can enable improved and sustained H2 gas recovery in this bioelectrochemical system.

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