Synthesis, characterisation and electrochemical application of hybrid nanocomposites of polyaniline with novel clay mineral

Abstract

Clay mineral obtained from Tuticorin in Tamilnadu, India (Indian Clay- IC) was purified and used to synthesise polyaniline-Indian clay nanocomposites (Pani-IC NCP) by polymerising aniline with the clay by chemical oxidation method using potassium perdisulphate as oxidant and by varying the aniline to clay ratio. The formation of composite in nanoscale was confirmed by XRD and TEM analysis. The in situ intercalative polymerization of monomer within the clays was ascertained by FTIR, UV–visible, XRD, SEM and TEM studies. The analyses of UV visible and FTIR spectroscopy demonstrated that aniline has been polymerized to Pani in its conducting emeraldine form. The conformation adopted by Pani Chains in the clay interlayer depended on the molar ratio of aniline to clay. SEM analysis showed the variation in morphology from granular agglomerate to layered flaky structure as the clay concentration was increased. Thermal stability of the nanocomposites was studied using TGA/DTA and DSC studies and it was found that they showed better thermal stability than their pristine polymers indicating the enhanced barrier property of the nanoclay. XRD showed that the clay host used accommodates higher amount of emeraldine salt than MMT. The Cyclic voltammetry studies of the synthesized nanocomposites showed the one with 0.5 g clay showed better electrochemical response. It exhibited good adherent behaviour on electrode surface at pH 1.0 with two oxidation peaks at 463 and 672 mV and two reduction peaks at 360 and 126 mV. By varying the atmosphere it was found that the nanocomposite modified electrode exhibited oxygen reducing capacity than their Bentonite counterpart. Chronoamperometric and Chronocoulometric studies were also carried out at inert as well as oxidising atmosphere which confirmed the above fact. EIS studies of the modified electrodes showed double layer capacitance value of 5.95 × 10−8 Fcm−2 with the bode phase angle of 70°.