Synthesis and Characterization of WO3 Thin Film by Spray Pyrolysis for Gas Sensing Application

Abstract

Nanostructured tungsten oxide (WO₃) thin-film sensor materials were deposited on a glass substrate by spray pyrolysis technique (SPT) and investigated their gas sensor properties. As prepared WO₃ thin films were characterized by different techniques such as UV-Visible Spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The optical band gap of film was determined using the absorption spectra obtained with UV-visible spectroscopy which was found to be 2.9 eV. XRD results of the as prepared WO₃ exhibits crystalline structure and favored alignment along the (002) axis. The spray pyrolysis technique used for the preparation of the WO₃ thin film often results in a porous and rough surface with a network of interconnected fiber-like structures., which are ideal for gas sensor applications due to increased surface exposure. The gas sensing performance of the WO₃ thin film was tested towards various gases such as H₂S, NH₃, LPG, H₂, ethanol, CO₂, Cl₂ at different operating temperatures. The WO₃ thin films exhibited their highest gas response to H₂S gas at an operating temperature of 50°C, with fast response and recovery times of 18 and 31 s, respectively. These results suggest that WO₃ thin films could serve as effective H₂S gas sensors.