Enhanced ammonia sensing characteristics of tungsten oxide decorated polyaniline hybrid nanocomposites

Polyaniline (PAni)-tungsten oxide (WO3) hybrid nanocomposites sensor have been lucratively synthesized by in-situ chemical oxidative polymerization method by entrapping tungsten oxide nanoparticles (10-50%) in the polyaniline matrix on precleaned glass substrate. The structural, morphological and surface composition elucidation of PAni-WO3 hybrid nanocomposites were explored by X-ray diffraction (XRD) technique, field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS). The existence of WO3 in PAni matrix and interaction between them was confirmed using XRD and Raman spectroscopy. The incorporation of WO3 nanoparticles into the PAni matrix introduces porosity which enhanced gas sensing properties. The TEM image of PAni-WO3 hybrid nanocomposite film exploded the average diameter of WO3 nanoparticles ranging from 40 to 50 nm. Chemical composition of PAni-WO3 hybrid nanocomposites was characterized by using X-ray photoelectron spectroscopy (XPS). In order to investigate the gas sensing parameter of PAni-WO3 hybrid nano composite, hybrid nanocomposite film was exposed to different oxidizing gases (Cl-2, NO2) and reducing gases (NH3, H2S, CH3OH, C2H5OH) in range 5-100 ppm concentration of gas. It was observed that the sensors of PAni-WO3 hybrid nanocomposites showed better sensitivity, selectivity, stability and reproducibility compared to pure PAni and pure WO3. PAni-WO3 (50%) hybrid nanocomposite sensor operating at room temperature reveals maximum response of 158% towards 100 ppm of NH3 gas and also capable to respond very little concentration of 5 ppm NH3 gas with reasonable response of 24%. The gas sensing mechanism of the nanocomposites in presence of air and with target NH3 gas atmosphere was discussed in detail with the help of energy band diagram. The interaction of NH3 and NO2 gas with PAni-WO3 hybrid nanocomposite sensor was investigated by employing an impedance spectroscopy also. (C) 2017 Elsevier B.V. All rights reserved.