Acceleration effect of gaseous CO2 on photobiocatalytic H2 formation by water splitting

Abstract Effects of gaseous CO2 on photocatalytic H2 formation by water splitting was studied for increasing activity of biocatalyst which was Escherichia coli (E. coli) expressing [FeFe]-hydrogenase. It was found that photobiocatalytic reaction under gaseous CO2 atmosphere, H2 formation rate increased by 283% at 60 min, and the amount of H2 formation increased by 105% at 300 min compared to under Ar atmosphere. This positive effect of gaseous CO2 was not simply explained by pH effects but assigned to the increased permeation rate of methyl viologen (MV2+), redox mediator, through cell membrane of E. coli. CO2 may be dissolved in cell membrane of E. coli and increased permeability of MV2+ resulting in increased formation rate of H2 by photobiocatalytic water splitting.