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A novel gas sensor based on Ag-doped WO3 nanostructures was successfully deposited on a glass substrate via electron beam evaporation technique. The microstructure, surface morphology, chemical composition, crystal structure, and optical properties of the pure and Ag-doped WO3 nanostructure thin films were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffractometer, and photoluminescence spectroscopy (PL). Gas-sensing tests revealed that the 15 wt% Ag-doped WO3 nanostructure possess excellent gas-sensing performance for ethanol. The sensitivity of the material toward 100 ppm ethanol was as high as 65 at an optimum operating temperature of 300 °C, which is higher than that of undoped WO3. The response/recovery times 9 s/11 s, great selectivity and outstanding long-term stability was obserevd for the 15 wt% Ag doped WO3 nanostructure sensor. The improvement of ethanol-sensing performance is related to the active space charge regions around the interface of Ag particles and WO3. [ABSTRACT FROM AUTHOR]

• Nanostructured WO 3 thin films were prepared by electron beam evaporation. • The gas sensing measurements were evaluated towards different operating temperatures, different gases and different concentrations. • When the substrate temperature increased to 100 °C, grain size of the film increased and nanorods appeared and possess a very high surface to volume ratio. • The films deposited at substrate temperature of 100 °C shows high response value of 58 towards ethanol gas. In the recent years, metal oxide semiconductors such as SnO 2 , CuO, Fe 2 O 3 , TiO 2 , WO 3 and ZnO were investigated for the detection of ethanol gas in the environment. Among these, WO 3 is one of the best n-type semiconductor material for ethanol gas detection. In this paper, nanostructured WO 3 thin films were prepared by electron beam evaporation on glass substrate and investigated their ethanol gas sensing properties. Surface morphology, structural and elemental analysis of the WO 3 thin films were analysed by scanning electron microscopy (SEM), atomic microscopy (AFM), X-ray diffraction and X-ray photoelectron spectroscopy. The as deposited films exhibited nanostructure and highly influenced by the substrate temperature. From the X-ray photoelectron spectroscopy analysis, we found that substrate temperature increases the binding energy shift in lower energy regions and shows that WO 3 films contain oxygen vacancies. The gas sensor sensitivities were measured for different gases with different concentrations at various operating temperatures. The obtained results show that the nanostructure WO 3 films are suitable sensing material for ethanol gas. The nanostructure WO 3 films deposited at substrate temperature of 100 °C shows best sensitivity with quick response and recovery time, which is attributed to the formation of nanorods and possess a very high surface to volume ratio. [ABSTRACT FROM AUTHOR]