M. A. Chougule

Synthesis and Characterization of Polyaniline:TiO2 Nanocomposites

Thin films of polyaniline (PANi) and PANi:titanium oxide (TiO2) composites have been synthesized by sol—gel spin coating technique. The TiO2 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 composite films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) Fourier transform infrared (FTIR) and UV-vis spectroscopy, and the results were compared with polyaniline films. The intensity of the diffraction peaks for PANi:TiO2 composites is lower than that for TiO2. The characteristic FTIR peaks of PANi were found to shift to a higher wave number in the PANi:TiO2 composite. These observed effects have been attributed to the interaction of TiO2 particles with PANi molecular chains. The room temperature resistivity of polyaniline:nano-TiO2 composite is 3.43 × 103 Ω cm and the resistivity of pure nano-TiO2 particles is 1.60 × 106 Ω cm.

SnO2nanoparticles-modified polyaniline films as highly selective, sensitive, reproducible and stable ammonia sensors

AbstractNanocomposites of polyaniline (PANi) and tin oxide (SnO2) were prepared by adding SnO2 nanoparticles (NPs) in different weight ratios (0%–50%) into the PANi matrix. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were used to form the polyaniline-SnO2 nanocomposites (PANi-SnO2) — a polymer-composite. PANi films modified with SnO2NPs were prepared by the spin coating method. The gas sensing properties of PANi, SnO2 and PANi-SnO2 polymercomposite films were observed and it was found that: The response of PANi film to 100 ppm NH3 at room temperature was 30% (stability 58%).The response of SnO2 film to 100 ppm NO2 was 19% (stability 79%) at operating temperature 200°C, which is higher than the room temperature. However, SnO2 exhibited no response to NO2 and NH3 at room temperature.The properties of the polymer-composite as a gas sensor were studied for various reducing (CH3OH, C2H5OH, NH3, H2S) as well as oxidising (NO2 and Cl2) gases. We demonstrated that the PANi-SnO2 (50%) polymer-composite film offers high stability and reproducibility and is a superior sensor to toxic gases operating at room temperature. (Results showed that they are highly selective to NH3 along with maximum response − 72% to 100 ppm, fast-response time of 167 s and better stability − 86% at room temperature. The unique nanostructure of this polymer composite with its high surface area offers these advantages.

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.

_{2}

The polyaniline-titanium dioxide (PANi-TiO₂) nanocomposite was prepared from PANi, and TiO₂, which were synthesized by oxidative chemical polymerization and sol gel methods, respectively. Nanocomposites of PANi- TiO₂ 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-TiO₂ thin-film sensors were prepared by the sol gel spin coating technique. The sensitivity measurements were carried out for ammonia (NH₃), ethanol (C₂H₅-OH), methanol (CH₃-OH), nitrogen dioxide (NO₂) and hydrogen sulfide (H₂S) gases, and it was found that the sensor exhibited selectivity to NH₃. The effect of varying doping percentage on response to varying NH₃ concentration was also studied. The result showed increasing response of sensor when NH₃ 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.

Nanocomposite

Thin films of polyaniline (PANi) and PANi: titanium oxide (TiO2) composites have been synthesized by sol–gel spin coating technique. The TiO2 powder of particle size 50–60 nm was synthesized by the sol–gel technique and the polyaniline was synthesized by the chemical oxidative polymerization of aniline. The composite films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy and the four-probe method. The results were compared with corresponding data on pure polyaniline films. The intensity of diffraction peaks for PANi:TiO2 composites is lower than that for TiO2. The characteristic FTIR peaks of pure PANi are observed to shift to a higher wavenumber in PANi:TiO2 composite, which is attributed to the interaction of TiO2 particles with PANi molecular chains. The resistivity measurement shows that the molecular chain constitution of polyaniline is the most important carrier in the polyaniline: nano-TiO2 composite.

New Method for Fabrication of CSA Doped PANi-

PPy/α-Fe2O3 hybrid nanocomposites with different weight percentages (10–50%) of CSA were successfully prepared by using a solid state synthesis method. Thin films of prepared hybrid nanocomposites were deposited on glass substrates using a spin coating technique and have been characterized using various techniques such as XRD, FESEM and TEM. The gas sensing performance of 10–50% CSA doped PPy/α-Fe2O3 nanocomposite thin films were studied towards NO2, Cl2, NH3, H2S, CH3OH and C2H5OH gases. Among various compositions, 30% CSA doped thin films were found to be highly sensitive and selective towards NO2 gas at room temperature i.e. with a chemiresistive response of 64% at 100 ppm with a reasonably fast response time of 148 s. The sensor responses in relation to the CSA doping concentration and the gas concentration have been systematically studied. Additionally, other sensing properties such as reproducibility, cross-sensitivity, sensing linearity and stability were also studied and explored. The CSA doped PPy/α-Fe2O3 nanocomposites exhibited better response, stability and shorter recovery times as compared to PPy and PPy/α-Fe2O3 nanocomposites alone. Therefore, it is expected that such a material with excellent gas sensing properties at room temperature can be used for high performance selective NO2 sensors.

{\rm TiO}_{2}

A nanocomposite of polyaniline-titanium dioxide (PANi-TiO2, 50 wt%) was doped with camphor sulfonic acid (CSA) by solid state reaction with increasing CSA content up to 50 wt% in a smooth agate mortar. CSA doped PANi-TiO2 was dissolved in m-cresol and films were cast using a spin-coating technique. The doping effect of CSA on PANi-TiO2 nanocomposite was characterized and evaluated by X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and electrical conductivity measurement. The XRD spectra showed that the addition of CSA has no effect on crystallinity of PANi-TiO2. SEM studies revealed that CSA has a strong effect on morphology of PANi-TiO2. The FTIR spectra revealed the interaction between CSA and PANi-TiO2 nanocomposite. Electrical conductivity measurements indicated that with the increasing content of CSA, the conductivity shows an orderly increase.

Thin-Film Ammonia Sensor

Nanocrystalline copper oxide (CuO) thin films were deposited onto glass substrates by a spin coating technique using an aqueous solution of copper acetate. These films were characterized for their structural, mor-phological, optoelectronic properties by means of X-ray diffraction (XRD) scanning electron microscopy (SEM), UVspectroscopy and four probe method. The CuO films are oriented along (1 1 1) plane with the monoclinic crystal structure. These films were utilized in H2S sensors. The dependence of the H2S response on the operating temperature, H2S concentration of CuO film (annealed at 700。C) was investigated. The CuO film showed selectivity for H2S. The maximum H2S response of 25.2 % for the CuO film at gas concentra-tion of 100 ppm at operating temperature 200oC was achieved.