Effect of NiO incorporation in charge transport of polyaniline: Improved polymer based thermoelectric generator

Abstract

The effect of nickel oxide (NiO) incorporation in the polyaniline (PANI) backbone has been studied here to accomplish an improved charge transport through the polymeric system and functionalizing it for thermoelectric (TE) applications. Polyaniline/nickel oxide (PANI/NiO) nanocomposites have been synthesized successfully by combining sol-gel and in situ chemical oxidative polymerization, using the ammonium persulfate as polymerizing agent in an acidic medium. The prepared nanocomposites have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and UV–Vis–NIR absorbance measurements. A shift in the band gap due to π- π* electronic transition has been observed on optical measurement. Carrier transport has become easier in the polymer chain due to its ordered chain orientation and its high conjugation, leading to high electrical conductivity. Further NiO nanoparticles in the polymer chain matrix reduce the barrier of interchain and intra-chain hopping. A remarkable increment (about three times of pure PANI) in thermo emf and Seebeck coefficient (S) has been recorded on incorporating NiO with the pure PANI. The results of TE studies and the electrical conductivity measurements show that this nanocomposite is of high potential as a TE generator. The maximum S value was recorded as 331 μV/°C.