Ag-doped WO₃ nanostructure films for organic volatile gas sensor application

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.