Synthesis and characterization of WO3 sensitive layers for NO2 gas sensor application

WO3 nanorods with loose inter-grain density have been successfully fabricated by the low-cost hydrothermal method. In addition, the capping agent significantly affects the morphology and the sensing mechanism of the WO3 sensor. The as-synthesized WO3 powder was tested for its morphology, structure, and phase using a scanning electron microscope (SEM) and X-ray diffraction (XRD). The sample WO3 has polycrystalline properties with a monoclinic crystal structure. The ethyl glycol monomethyl ether (EGME) acts as a structure-directing agent in the nanorod formation with the loose density of the WO3 sample. The nanorod form of WO3 produces a high gas response value of 68.4 to 2 ppm of NO2 gas at a quite low operation temperature of 150 °C. The morphology of WO3 modified by EGME supports the gas response characteristics of the WO3 sensor to NO2 gas. The sensor test results show that WO3 with nanorod morphology with a loose density can be a good base for NO2 gas sensors to be applied.