2-D Nanosheets and Rod-Like WO 3 Obtained via Chemical Precipitation Method for Detecting Formaldehyde

In this paper, WO3 nanosheets and rod-like were successfully prepared via chemical precipitation method for efficient sensing of formaldehyde gas at low working temperature. The structure and morphology of the precursors and the calcined products in air were characterized X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analyses confirmed that the precursors were compound of monoclinic structure WO3 and orthorhombic structure WO3 · 0.33H2O, whereas monoclinic structure WO3 were obtained by calcining at 450 °C for 2 h. Sensors fabricated by calcined WO3 exhibited a quick response (5 s)/recovery (15 s) characteristic. The gas sensing texts showed the response value (Ra/Rg = 16.5) to 100 ppm HCHO at the optimum temperature of 300 °C. The possible oxidation-reduction reaction mechanism of HCHO molecule on the sensor surface were researched and discussed too. WO3 could be a promising sensing materials for detecting organic pollutants.