Multifaceted tungsten oxide films grown by thermal evaporation

• We obtained multifaceted tungsten oxide microcrystals by thermal evaporation.
• Multifaceted crystals are composed of plates that grow radially on SiO2/Si substrate.
• Tungsten oxide film is resistant to leaching and present low band gap value.

Thermal evaporation, compared to other vapor phase deposition techniques, is a simple low-cost method to obtain films. Multifaceted tungsten oxide microcrystals were grown as films by the thermal evaporation of tungsten trioxide on (100) silicon substrates covered with SiO2 layer, which were arranged vertically inside a horizontal furnace. The structural characterization of these films was carried out through micro-Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, scanning electron microscopy and Rutherford backscattering spectrometry. The crystals are composed of monoclinic and hexagonal WO3 phases that grew as plates and were arranged radially around multifaceted nuclei. The films present photocatalytic activity, which is evidenced by the accelerated degradation of methyl orange dye, and are resistant to leaching in aqueous media. This initial characterization will enable further exploration of these films as photocatalysts.