In situ synthesis, characterization, conductivity studies of polypyrrole/silver doped zinc oxide nanocomposites and their application for ammonia gas sensing

The synthesis of polypyrrole (PPy)/silver doped zinc oxide (Ag-ZnO) nanocomposites have been carried out by employing a simple and environmentally benign in situ polymerisation strategy. The structural, morphological and thermal properties of nanocomposites were characterised through Fourier transform infrared spectra (FTIR), X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The FTIR spectra revealed the formation of nanocomposite by the shift in the characteristic peak of PPy to a lower wavenumber region in PPy/Ag-ZnO nanocomposite. The effective utilisation of the surface of the Ag-ZnO nanoparticles by PPy chains was also confirmed from X-ray diffraction. The SEM and TEM images revealed the good interaction between Ag-ZnO and PPy up to a loading of 10 weight percentage (wt%). TGA studies indicated the excellent thermal stability of the polymer nanocomposite. DSC results revealed that the glass transition temperature of the nanocomposite was increased with increase in the concentration of nanoparticles. The electrical properties of the nanocomposites were studied from the direct current (DC) and alternating current (AC) resistivity measurements. The dielectric properties, AC and DC conductivity of the nanocomposites were significantly increased with increase in content of nanoparticles. The sensitivity of ammonia gas through the nanocomposites was also evaluated with respect to different contents of nanoparticles. The ammonia sensing properties of nanocomposite was higher than that of pure PPy and the maximum sensor response was observed for 10 wt% of composite.