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

Abstract

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.