Hydrothermally synthesized tungsten trioxide nanorods as NO2 gas sensors

One-dimensional single-crystalline h-WO3 nanorods have been synthesized by using a facile hydrothermal technique. Crystal structure, morphology evolution and thermal stability of the products are characterized by using X-ray Diffraction pattern, Scanning Electron Micrographs, Photoluminescence reflectance spectrum; UV-vis diffused reflectance spectral analysis and Raman techniques. The evolution and distribution of WO3 nanorods strongly depend on hydrothermal reaction temperature and time of reaction. Hydrothermal reaction temperature of 170 degrees C for 48 h ensures the formation of well-defined agglomerated WO3 nanorods. Gas response measurements reveal that WO3 sensor operating at 250 degrees C exhibits highest sensitivity towards NO2 with low cross sensitivity towards LPG, acetone and ammonia gas, which makes this material a competitive candidate for NO2 sensing applications. A possible adsorption and reaction model is proposed to illustrate formation of one dimensional nanostructure and gas sensing mechanism. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.