Detection of H2S,SO2, and NO2 using electrostatic sprayed tungsten oxide films

This paper presents the electrostatic spray deposition of tungsten oxide (WO₃) films for the detection of different pollutant gases. The influence of several types of precursors on the structure and morphology of the films was studied by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. This preliminary study allowed to select the proper precursor for the preparation of pure and porous WO₃ films which offer high gas response (R_air/R_gas=1200) to low concentrations of H₂S (10 ppm) at low operating temperature (200 °C). The gas response to NO₂ and SO₂ is low at this temperature suggesting no possible interference with these two gases during the H₂S detection. Furthermore, the films are able to detect very low concentrations of NO₂ (less than 1 ppm) at 150 °C.