Fabrication of a room-temperature H2S gas sensor based on PPy/WO3 nanocomposite films by in-situ photopolymerization

An H2S gas sensor for use at room temperature was fabricated by the in-situ photopolymerization of a nanocomposite thin film of polypyrrole (PPy) and tungsten oxide (WO3) nanoparticles (PPy/WO3) on an alumina substrate. X-ray diffractometry (XRD) and scanning electron microscopy (SEM) were used to analyze the structure and morphology of the fabricated films. Comparative gas sensing results revealed that the sensor that was based on the PPy/WO3 nanocomposite film had much more response than that based on pure WO3 or PPy film in the detection of H2S gas at room temperature. Microstructural observations revealed that PPy distributed into the PPy/WO3 nanocomposite film. Therefore, a model of the potential barriers to electronic conduction in the composite material was used to determine that the high response was associated with the stretching of the depletion layers at the interface of the PPy with the WO3 film when the detected H2S gases are adsorbed at room temperature. The sensor that was based on a nanocomposite film of PPy/WO3 responded strongly to very low concentrations of H2S gas at room temperature and its use is practical because of it is easy to fabricate.