Synthesis and characterization of polypyrrole/H-Beta zeolite nanocomposites

Abstract

Different amounts of polypyrrole (PPy) were synthesized in aqueous solution on zeolite frameworks by chemical oxidation using FeCl₃ as the oxidizing agent at ambient temperature (22 ± 1 °C). The proton form of BEA zeolites with SiO₂/Al₂O₃ ratios of 25, 150 and 300 were used as the host for PPy in this study. Both the anionic groups in the zeolite structures and the chloride ions from the oxidant functioned as the dopants during the polymerization. For comparison, parallel experiments were carried out with only purified pyrrole and FeCl₃ in water solution in order to obtain the bulk PPy powder. The nitrogen adsorption–desorption technique, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) were used to characterize the composites. PPy was formed both in the inner and outer surface of the zeolite structures. The composites showed electrical conductivity at ambient temperature in the range from 6.2 × 10⁻⁶ to 1.3 S cm⁻¹ depending on the ratio between pyrrole and H-Beta zeolite. Electrochemical behavior of the synthesized samples was investigated by cyclic voltammetry.