P. R. Godse

Polypyrrole Thin Film: Room Temperature Ammonia Gas Sensor

Polypyrrole thin films were synthesized in situ by chemical polymerization. The morphological studies by Scanning Electron Microscopy showed formation of uniform granular structure with average grain size of 0.6 μm. Fourier transform infrared spectroscopy revealed formation of polypyrrole. The film composition was also characterized by UV-Vis Spectroscopy. These films were investigated for their sensing behavior towards NH3, C2H5OH and CH3OH gases at room temperature. It has been observed that these films are selective for ammonia gas, and the sensitivity exhibited a linear response in range of 5-100 ppm. These studies show that polypyrrole films can be used as room temperature ammonia sensors.

Structural, Morphological, Optical, and Electrical Properties of PANi-ZnO Nanocomposites

Thin films of polyaniline (PANi) and PANi–Zinc oxide (ZnO) nanocomposites have been synthesized by a spin-coating technique. The ZnO powder of particle size 50–60 nm was synthesized by sol–gel technique and the polyaniline was synthesized by chemical oxidative polymerization of aniline. The nanocomposite films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), UV–Vis spectroscopy, and four probe technique, and the results were compared with polyaniline films.

Room Temperature Ammonia Gas Sensor Based on Polyaniline-TiO

In the present work, we report on the performance of room temperature ammonia gas sensor based on polyaniline-titanium dioxide (PANi-TiO2) nanocomposite. The nanocomposite was fabricated using the spin coating method on glass substrates. PANi-TiO2 (0%-50%) nanocomposite films were characterized for their structural as well as surface morphologies, UV-Vis and various gas responses were studied. The XRD analysis showed formation of nanocrystalline TiO2, while polyaniline exhibited amorphous nature. Morphological analysis using scanning electron microscopy of PANi-TiO2 nanocomposite film revealed uniform distribution of TiO2 nanoparticles in PANi matrix. The absorption peaks in FTIR and UV-Vis spectra of PANi-TiO2 composite film were found to shift to a higher wave number as compared to those observed in pure PANi. The observed shifts were attributed to the interaction between the TiO2 particle and PANi molecular chains. The gas sensing properties showed the sensor exhibit selectivity to ammonia (NH3) at room temperature.

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The PANi-SnO2 hybrid nanocomposite based thin films doped with 10–50 wt % CSA were deposited on the glass substrates using the spin coating technique. The sensor response in relation to the CSA doping concentration and the gas concentration has been systematically studied. A significant sensitivity (91%) towards 100 ppm NH3 operating at room temperature is observed for the 30 wt % CSA doped PANi-SnO2 nanohybrid. The sensing mechanism of CSA doped PANi-SnO2 materials to NH3 was presumed to be the effect of p–n heterojunctions.

Nanocomposite

The nanocrystalline CuO thin films were prepared on glass substrates by the sol‐gel method. The structural, morphological, electrical and optical properties of CuO thin films, submitted to an annealing treatment in the 400–700 °C ranges are studied by X‐ray diffraction (XRD), Scanning Electron Microscopy (SEM), Four Probe Technique and UV‐visible spectroscopic. XRD measurements show that all the films are crystallized in the monoclinic phase and present a random orientation. Four prominent peaks, corresponding to the (110) phase (2θ≈32.70°), (002) phase (2θ≈35.70°), (111) phase (2θ≈38.76°) and (202) phase (2θ≈49.06°) appear on the diffractograms. The crystallite size increases with increasing annealing temperature. These modifications influence the microstructure, electrical and optical properties. The optical band gap energy decreases with increasing annealing temperature. These mean that the optical quality of CuO films is improved by annealing.

NH3 sensor based on CSA doped PANi-SnO2 nanohybrid

Nanocrystalline titanium oxide thin films have been deposited by spin coating technique and then have been analyzed to test their application in NH3 gas‐sensing technology. The X‐ray diffraction measurements confirmed that the films grown by this technique have good crystalline tetragonal mixed anatase and rutile phase structure. The surface morphology (SEM) of the TiO2 film showed that the nanoparticles are fine Gas sensing properties showed that TiO2 films were sensitive as well as fast in responding to NH3. A high sensitivity for ammonia indicates that the TiO2 films are selective for this gas.