New Method for Fabrication of CSA Doped PANi- ${\rm TiO}_{2}$ Thin-Film Ammonia Sensor

The polyaniline-titanium dioxide (PANi-TiO ₂ ) nanocomposite was prepared from PANi, and TiO ₂ , which were synthesized by oxidative chemical polymerization and sol gel methods, respectively. Nanocomposites of PANi- TiO ₂ were doped with Camphor Sulfonic Acid (CSA) with concentrations as high as 50 wt%. The composites obtained (PT CSA) were characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). The CSA doped PANi-TiO ₂ thin-film sensors were prepared by the sol gel spin coating technique. The sensitivity measurements were carried out for ammonia (NH ₃ ), ethanol (C ₂ H ₅ -OH), methanol (CH ₃ -OH), nitrogen dioxide (NO ₂ ) and hydrogen sulfide (H ₂ S) gases, and it was found that the sensor exhibited selectivity to NH ₃ . The effect of varying doping percentage on response to varying NH ₃ concentration was also studied. The result showed increasing response of sensor when NH ₃ concentration was changed from 20 to 100 ppm. It was also found that, the sensor exhibited smaller response time and larger response magnitude but at the cost of longer recovery time.