Photoelectrochemical reforming of glucose for hydrogen production using a WO3-based tandem cell device

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The development of low-cost processes for hydrogen production from renewable energy is of tremendous importance for a truly sustainable hydrogen-based energy system. In this article, we demonstrate the ability to utilize sunlight to produce hydrogen from a potentially low-cost and abundant biomass derivative, glucose, using a WO3-based tandem photoelectrochemical cell (PEC). Thin film WO3 photoelectrodes are shown to exhibit excellent photocatalytic activity towards the oxidation of a variety of complex oxygenates, with photocurrents that are nearly equal to those achieved in the presence of simple alcohols such as methanol and ethanol. This result indicates that WO3-based PEC reactors can be used as a feedstock-flexible technology. High performance liquid chromatography and gas chromatography were utilized to analyze glucose degradation and product formation, respectively, showing that glucose is ultimately oxidized to a mixture of CO and CO2 that depends on reaction conditions. These results suggest that the photoelectrode surface and operating conditions may be adjusted to optimize the production of either H2 or syngas (H2 + CO). In addition to half-cell measurements, unassisted electrolysis of glucose was demonstrated with a tandem cell device consisting of a WO3 photoelectrode, CdTe bottom cell, and WC counter electrode. Using this tandem configuration, a stable short-circuit current density of 1.38 mA cm−2 was recorded under outdoor illumination in 0.33 M H2SO4/0.1 M glucose. This PEC device utilizes no precious metal catalysts and shows great potential as a low-temperature pathway towards H2 and/or syngas production from renewable energy.