Composites of Fe2O3 nanosheets with polyaniline: Preparation, gas sensing properties and sensing mechanism

- Fe2O3 nanosheets are prepared by hydrothermally treating electrospun nanofibers.
- Fe2O3/polyaniline nanocomposite show ultrahigh sensitivity and selectivity to NH3.
- High sensing performance of the nanocomposite relates to p-n heterojunction.

Fe2O3 nanosheets were in-situ deposited on the interdigitated gold electrodes by hydrothermal treatment of the electrospun nanofibers containing FeCl3 and poly(vinyl butyral). As-prepared electrode was further dip-coated with water-dispersible polyaniline (PANI) to fabricate a resistance gas sensor based on Fe2O3/PANI nanocomposite. The structure and morphology of the nanocomposite were investigated by X-ray diffraction pattern, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. It was found that the nanocomposite sensor exhibited much higher response magnitude towards low concentration of NH3 (0.5-10.7 ppm) than the sensors based on either PANI or Fe2O3 at room temperature (∼20 °C), indicating an obvious synergetic effect. The nanocomposite sensor was featured with ultra high response magnitude (relative resistance change of ∼3070% towards 10.7 ppm of NH3) and excellent selectivity towards NH3. A sensing mechanism has been put forward, which takes into account of the conducting network comprising of bulk PANI and composites of PANI and Fe2O3 nanosheets. It was proposed that the p/n heterojunction established between Fe2O3 nanosheets and PANI coating played a major role in the highly desirable sensing performance of the composite.

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