Enhanced thermoelectric behaviour and visible light activity of Ag@TiO2/polyaniline nanocomposite synthesized by biogenic-chemical route

Abstract

This paper reports the synthesis of a visible light-active Ag@TiO₂/Pani nanocomposite through a facile biogenic-chemical route. The Ag@TiO₂/Pani nanocomposite was prepared by the in situ oxidative polymerization of aniline in the presence of an Ag@TiO₂ nanocomposite, which was obtained via a biogenic route. The synthesized Ag@TiO₂/Pani nanocomposite was confirmed by UV-visible spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and thermogravimetric analysis. The Ag@TiO₂/Pani nanocomposite was doped with HCl or para-toluene sulfonic acid to render it conducting. An analysis of the thermoelectrical behavior using a cyclic aging technique showed that the electrical conductivity and thermal stability of Pani was improved after incorporation of Ag@TiO₂ to form an Ag@TiO₂/Pani nanocomposite system. Photocatalytic studies of the Ag@TiO₂/Pani nanocomposite revealed superior photodegradation properties in comparison to Pani towards the degradation of methylene blue and brilliant blue under visible light, even after repeated use. Electrochemical impedance spectroscopy and linear sweep voltammetry in the dark and under visible light irradiation also supported the visible light photocatalytic activity of Ag@TiO₂/Pani due to a decrease in the electron transfer resistance resulting in an increase in photocurrent. Therefore, the enhanced thermoelectric, photoelectrochemical and photodegradation properties of these materials suggest them to be a suitable replacement for Pani in the near future.