Current Doubling effect revisited: Current multiplication in a PhotoFuelCell

• Current Doubling effect revisited.
• Separation of Current Doubling from other causes of current increase.
• Current Doubling in the presence of ethanol, glycerol and xylitol.
• Operation of PhotoFuelCells with sensitized photoanode.

Current Doubling effect is the current multiplication due to the formation of unstable radicals followed by electron injection into the conduction band of a photocatalyst in a photoelectrochemical cell functioning in the presence of sacrificial agents. When other causes of current increase are present, it is difficult to separate current increase due to pure Current Doubling. Especially, in the case of nanostructured semiconductor photocatalysts, the presence of sacrificial agents leads to current increase by scavenging holes and thus suppressing electron–hole recombination. This matter has been studied in the present work by monitoring the current flowing in a PhotoFuelCell, i.e. in a photoelectrochemical cell functioning in the presence of an organic sacrificial agent acting as “fuel”. Three biomass-derivable model fuels have been examined, namely, ethanol, glycerol and xylitol. Current Doubling was clearly demonstrated in the case of ethanol where the photocurrent efficiency reached values higher than 100%.

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