Preparation and optical/electrical/electrochemical properties of expanded graphite-filled polypyrrole nanocomposite

Expanded graphite filled polypyrrole (PPy/EG) conducting composites were prepared by in situ polymerization of pyrrole by the addition of expanded graphite in various proportions (0.25%, 0.50% and 1.0%). The synthesized samples were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), ultraviolet–visible absorption (UV–vis), X-ray diffraction (XRD) and electrical conductivity measurements. FTIR spectroscopy revealed the interaction between expanded graphite and polypyrrole (PPy). PPy/EG composites showed crystalline nature with rhombohedral structure. The band gaps of pure PPy and PPy/EG composites were determined by UV–vis absorption spectrophotometry and cyclic voltammetry. The electrical conductivities of the composites were enhanced dramatically to 110.04 S cm−1 compared to pure PPy. The composites also showed excellent electrochemical reversibility at the scan rate of 0.1 V s−1 and maximum reversible electrochemical response intaking charge capacity almost unchanged even up to 125th cycles.