Parameters affecting the chemical work output of a hybrid photoelectrochemical biofuel cell

Michael Hambourger, Paul A. Liddell, Devens Gust, Ana Moore, Thomas Moore

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


A hybrid photoelectrochemical biofuel cell employing the photoanode architecture of a dye-sensitized solar cell has been assembled. A porphyrin dye sensitizes a TiO2 semiconductor over the visible range to beyond 650 nm. Photoinduced charge separation at the dye–TiO2 interface results in electron migration to a cathode, and the holes generated on surface bound dyes oxidize soluble electron mediators. The increased [Ox] : [Red] ratio of the mediator drives the solution-based enzymatic oxidation of appropriate substrates. In this report we investigate how the accumulation of anodic and cathodic products limits cell performance. The NAD+/NADH and benzoquinone/hydroquinone redox couples were studied as sacrificial electron donors in the absence of appropriate enzymes or substrates. Comparatively poor cell performance was observed using the benzoquinone/hydroquinone couple. This effect is explained in terms of rapid charge recombination by electron donation from the electrode to benzoquinone in solution, as compared to much less recombination with NAD+. With the NAD+/NADH couple the cell performance is relatively independent of the redox poise of the anode solution, but limited by accumulation of reduction products in the cathodic compartment. Using the NAD+/NADH couple, the photochemical reforming of ethanol to hydrogen was demonstrated under conditions where the process would be endergonic in the dark.

Original languageEnglish (US)
Pages (from-to)431-437
Number of pages7
JournalPhotochemical and Photobiological Sciences
Issue number4
StatePublished - Apr 2 2007

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry


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