Photocatalytic H2 and O2 evolution over tungsten oxide dispersed on silica

Tungsten oxide dispersed on silica (WO3/SiO2) as photocatalysts was prepared by sol–gel method and characterized with various techniques, including X-ray diffraction (XRD), UV Raman spectroscopy (UV Raman), UV–vis spectroscopy (UV–vis), N2-adsorption, X-ray photoelectron spectra (XPS), and high-resolution transmission electron microscopy (HRTEM). The characterization results show that most of tungsten oxide species are present as nanoparticles, which are highly dispersed on the surface of silica. Compared to bulk WO3, WO3/SiO2 exhibits relatively high visible-light-driven O2 evolution activity in the presence of Fe3+ ions as sacrificial reagents. Interestingly, it is found that WO3/SiO2 also shows H2 evolution activity with methanol as sacrificial reagents under UV light. The high photocatalytic O2 evolution and unexpected H2 generation properties of WO3/SiO2 could be correlated with the presence of highly dispersed WO3 nanoparticles and their interface W–O–Si like species.