Synthesis and Analysis of Thin Films of Polyaniline Doped with Tetraoxosulphate (VI) and Citric Acid

Abstract

Polyaniline (PANI) has been extensively studied because of ease in synthesis, unique stability (in the presence of oxygen) and electrochemical properties. In this research work, three samples of (PANIthin films were synthesized by using chemical oxidative polymerization of aniline in the presence of Hydrochloric (HCl) acid using Ammonium peroxydisulfate (APS) as an oxidizing agent. Two of the synthesised PANI thin film samples were doped with Tetraoxosulphate( VI) acid (H2SO4) and Citric acid, while the third synthesised PANI thin film sample was left un-doped to serve as a control. Veeco Dektak 150 Profilometer was used to measure the thickness of the films; while variations in the optical, electrical and structural properties of the samples were investigated using Ultraviolet-visible (UV-Vis) spectroscopy, four point probe and X-Ray Diffraction (XRD) pattern respectively. The results showed that the thin films were of the same thickness (0.2µm) and their absorption spectra revealed two absorption peaks at about 300nm and 650nm for the pure and citric acid-doped samples, while the H2SO4-doped PANI had its peaks at about 300 nm and 880nm. Doping reduced the direct band gap of the PANI from 2.75 Electron volt (eV) to 2.4eV. The electrical characterization results revealed that the H2SO4-doped PANI has the best conductivity among all the doped samples, while the pure sample showed no electrical conductivity. Furthermore, the analysis of XRD patterns showed that the samples were crystalline in nature.

Keywords: Chemical oxidative polymerization, citric acid, conducting polymers, doped-polyaniline thin film.
Cite this Article: O. N. Paul- Nwokocha, E. Anthony , J. O. Ozumba. Synthesis and Analysis of Thin Films of Polyaniline Doped with Tetraoxosulphate (VI) and Citric Acid. International Journal of Computational Biology and Bioinformatics. 2019; 5 (1): 6–14p.