Ammonia gas sensing properties of CSA doped PANi-SnO2 nanohybrid thin films

The polyaniline (PANi)-SnO2 nanohybrid based thin films doped with 10–50 wt % camphor sulfonic acid (CSA) were deposited on the glass substrates using spin coating technique. The crystallinity, chemical structure and morphology of the films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Field emission scanning electron microscopy respectively, which proved that there is a strong synergetic interaction between the CSA and PANi-SnO2 nanohybrid. The sensor response was estimated by the change in the electrical resistance of the film in the absence and presence of ammonia (NH3) gas. The sensor response and selectivity in relation to the CSA doping concentration and the gas concentration has been systematically studied. A significant sensitivity (91%) and fast response (46 s) toward 100 ppm NH3 operating at room temperature is observed for the 30 wt % CSA doped PANi-SnO2 nanohybrid film. The sensing mechanism of CSA doped PANi-SnO2 nanohybrid film to NH3 was presumed to be the synergism of PANi and SnO2 or the effect of p–n heterojunctions.