Temperature and acidity effects on WO3 nanostructures and gas-sensing properties of WO3 nanoplates

Abstract WO 3 nanostructures were successfully synthesized by a facile hydrothermal method using Na 2 WO 4 ·2H 2 O and HNO 3 as raw materials. They are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The specific surface area was obtained from N 2 adsorption–desorption isotherm. The effects of the amount of HNO 3 , hydrothermal temperature and reaction time on the crystal phases and morphologies of the WO 3 nanostructures were investigated in detail, and the reaction mechanism was discussed. Large amount of acid is found for the first time to be helpful to the oriented growth of tungsten oxides, forming nanoplate-like products, while hydrothermal temperature has more influence on the crystal phase of the product. Gas-sensing properties of the series of as-prepared WO 3 nanoplates were tested by means of acetone, ethanol, formaldehyde and ammonia. One of the WO 3 nanoplates with high specific surface area and high crystallinity displays high sensitivity, fast response and distinct sensing selectivity to acetone gas.