Thermally stable WO3 nanostructure synthesized by hydrothermal method without using surfactant

The effect of hydrothermal parameters was investigated on the structural, morphological and optical properties of tungsten oxide (WO3) nanostructures synthesized without any additives. Also, the thermal stability of products was studied at 350 °C. The products were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), Raman scattering and diffuse reflection spectroscopy (DRS). The results emphasized that the WO3 features depended on the synthesis duration and pH value. The formation of rod-like WO3 nanostructures was verified by FESEM analysis. The crystallite size and bandgap were in the range of 40–89 nm and 2.63–2.94 eV, respectively, that increased with pH enhancement. Although the crystallite size was decreased with hydrothermal duration decrement, the bandgap did not show significant change. Also, the obtained nanorods shortens in length with decreasing synthesis duration. The slight variation caused by calcination makes samples suitable for high temperature applications like gas sensors.