COMPARATIVE STUDIES ON MICROSTRUCTURAL AND GAS SENSING PERFORMANCE OF TiO2 AND TiO2-PANi NANOCOMPOSITE THIN FILMS.

In recent years, the development of inorganic-organic hybrid materials has grown due to better properties and wide range of potential use. The aim of this research is to investigate the effect of PANi addition on VOC gas sensing properties and microstructures of TiO2 based thin films. TiO2 ceramics were prepared via sol-gel technique. PANi, in amount of 3wt % was added to TiO2 sol to produce TiO2-PANi solution. Then TiO2 and TiO2-PANi solutions were deposited onto SiO2 coated silicon substrate using spin coating technique for fabrication of gas sensing device. XRD investigation showed that the thin films were amorphous. TEM study of the TiO2 and TiO2-PANi powders revealed a significant reduction of TiO2 particles size from 10nm to 2nm with the addition of PANi. SEM micrographs showed that both films exhibit an open porous structure with TiO2 rich grain particles well distributed on the substrate. The gas sensing devices were exposed towards VOCs vapours. It was found that the device with addition 3wt % of PANi exhibit a systematic response towards ethanol and methanol vapour exposure at room temperature. In contrast TiO2 thin film did not show any response due to low operating temperature