Integrated approach for efficient humidity sensing over zinc oxide and polypyrole composite.

Synergism between individual components of a polymer composite evolve many promising interfacial surface properties for wide range of applications. The significant synergism in sensing materials are responsiveness to conductance; catalysis to luminescence; absorbance to porosity. In this context, present work reports the preparation of polypyrrole and zinc oxide (PPy/ZnO) composite by in-situ polymerization and composite formation (I.P.C.F.) technique. Thus obtained materials have been characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques for their structural and morphological properties. The results prove the formation of composite with optimized crystallinity, electrical conductivity and mechanical properties. The optimization effect in the properties of ZnO/PPy and pure PPy films were studied and result indicates the enhancement in the electrical conductivity of ZnO/PPy than PPy due to the higher ionization in ZnO/PPy than pure PPy along with humidity responsive behavior. Further, ZnO/PPy composite has been explored for humidity sensing purposes by monitoring the electrical resistance against different humidity level of a closed chamber. The observed humidity sensing parameters are response time 12 s, recovery time 8 s and negligible interference. The sensing behavior has been explained with an appropriate schematic model using synergistic effect between ionization and dissociative adsorption of water molecules.