Hydrogen storage capacity of polypyrrole in alkaline medium: effect of oxidants and counter anions

Abstract

Polypyrrole(Ppy) synthesized by wet chemical method using FeCl3 and (NH4)2S2O8 as oxidants were subjected to analysis by Scanning Electron Microscopy, X-ray diffraction, UV-visible spectroscopy, Differential scanning calorimetry, Raman and 1HNMR techniques. Electrochemical analysis such as cyclic voltammetry, linear sweep voltammetry and impedance spectroscopy of Ppy were performed. Charge/Discharge studies in 0.01 M NaOH showed hydrogen storage capacity of PpyFeCl3 and PpyAPS as 27.24 and 24.4 mA h/g respectively, implying stable hydrogen storage by PpyFeCl3. This variation in the ability of storing hydrogen by Ppy with change in oxidants is attributed to the formation of anion induced H-bonded structures in the backbone of Ppy as supported by Raman and 1HNMR analysis. Keywords: Polypyrrole, Raman spectroscopy, Electrochemical analysis, Hydrogen storage