Bi 2O 3–WO 3 compounds for photocatalytic applications by solid state and viscous processing

Abstract

Water-splitting photoelectrochemical cells utilising photocatalysts have the potential to become a significant hydrogen source for fuel cells. Historically, the photocatalytic properties of TiO 2 and other compounds have been carefully investigated, but they suffer from poor energy conversion efficiencies for solar radiation. Inspired by the low bandgaps and high electrical conductivities of WO 3 and Bi 2O 3, this study investigates the suitability of compounds within this binary system as efficient photocatalysts. The structure and optical absorption spectra of these compounds have been determined via X-ray diffraction and UV–vis spectroscopy over the range of 300–900 nm. The semiconductor bandgaps of Bi 2O 3, WO 3 and Bi 2WO 6 were found to be 0.2 eV, in agreement with previously reported results. Two sample preparation techniques have been considered—solid-state processing and viscous processing techniques. A custom-built, computerised micro-coextrusion system has been used to prepare intermediate compounds from the WO 3–Bi 2O 3 binary oxide system and the design and optimisation of this technique are discussed.