Green Synthesised Bismuth Ferrite for PVA-PANI-BFO Polymer-Nanocomposite Membrane: Impacts on Ionic Conductivity with Variation of Relative Humidity

Bismuth ferrite (BFO) nanoparticles were synthesised by an environment-friendly process using the moringa oleifera leaf extract. The synthesised BFO nanoparticles were used as nanofiller to synthesise PVA-PANI-BFO polymernanocomposite membrane. Also, the PVA-PANI polymer membrane was synthesised for a comparative study purpose between PVA-PANI and PVA-PANI-BFO membranes. Both the polymer and polymer-nanocomposite membranes were synthesised by the solution cast technique. The Green synthesised BFO nanoparticles and the synthesised membranes were characterised by spectroscopic techniques such as X-ray diffraction (XRD), RAMAN and fourier-transform infrared spectroscopy (FTIR). XRD patterns confirm the BiFeO3 phase of the synthesised BFO nanoparticles, as well as the existence of PVA, PANI and BFO in the membrane. The Raman spectrum for the synthesised nanoparticles exhibits BFO characteristic bands. The bands of polyvinyl alcohol (PVA) and polyaniline (PANI) are also seen for the membranes. FTIR spectrum indicates some phytochemicals as the functional groups in the synthesised BFO nanoparticles. The surface structures of the synthesised membranes were characterised by field emission scanning electron microscopy (FESEM). Ionic conductivities of the synthesised membranes were calculated by estimating bulk resistance of them from Cole-Cole plots that were obtained with the help of an impedance spectrometer. The conductivities of the membranes change with the relative humidity (RH).