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 (Rair/Rgas=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.