Facile in-situ synthesis, microstructural, morphological and electrical transport properties of polypyrrole-cuprous iodide hybrid nanocomposites

Abstract

In this study, polypyrrole cuprous iodide (PPy-CuI) hybrid nanocomposites were synthesized in an aqueous medium via an in-situ chemical oxidation route with ammonium persulphate as an oxidizing agent to report the microstructural, morphological, and electrical properties of as-synthesized specimens. By using an in-situ oxidative polymerization method, sonochemically synthesized γ-CuI nanocrystals were mixed with a PPy matrix in varying weight percentages (10–40 ​%). The purity, crystallinity and structure of hybrid nanocomposites were determined using X-ray diffractometry. The average crystallite size of hybrid nanocomposites was calculated using the Debye-Scherrer, Williamson-Hall and Size-Strain plot methods. All specimens' intrinsic strain was estimated using the Williamson-Hall plot and the Size-Strain plot methods. The field emission scanning microscopy revealed that the surface morphology changed from granular to overgrown clusters as the weight percent of CuI nanocrystals is increased from 10 to 40 ​% in PPy-CuI hybrid nanocomposites. The Fourier transform infrared spectroscopy indicates the formation of PPy and successful insertion of γ-CuI nanocrystals into the PPy matrix. The room temperature dc electrical conductivity is found to decrease from 6.3 ​× ​10−2 Scm−1 to 1.70 ​× ​10−3Scm−1as the wt% of γ-CuI nanocrystals increases from 10 to 40 ​% in hybrid nanocomposites. Furthermore, the increasing trend of dc conductivity with temperature is due to all samples' semiconducting nature. In the temperature range of 200–300 ​K, the measured experimental data followed the Arrhenius and Mott's 3d variable range hopping (VRH) model. The values of average activation energy, average hopping energy, density of states at Fermi level, average hopping distance and Mott's characteristic temperature of PPy-CuI (40 ​%) hybrid nanocomposites at 300 ​K were estimated to be ~60 ​meV, ~29 ​meV, 6.36 ​× ​1022 ​cm−3eV−1, 5.06 ​Å and 1901 K, respectively.