Ag decorated WO3 sensor for the detection of sub-ppm level NO2 concentration in air

The WO3 has been broadly investigated for its application in the field of gas sensing. WO3 material was successfully synthesized by sol-gel method and the Ag nanoparticles decorated on WO3 sensor using drop-cast method. The morphological, structural and chemical properties of pure WO3 and Ag decorated WO3 (Ag-WO3) films were investigated using FESEM, AFM, EDX, HRXRD, XPS and TEM. The fabricated sensors were investigated at various operating temperatures (50–300 °C) and NO2 gas concentrations (0.1–3 ppm). The gas sensing study reveals that the 0.5%Ag-WO3 sensor shows higher NO2 sensing response at an operating temperature of 200 °C. The sensor has high selectivity for NO2 gas in the presence of different interfering gases such as NH3, acetone, SO2, methanol, CO2, NO and NO2. The sensor showed excellent reproducibility for NO2 gas response.