Water-soluble polyaniline/graphene composites as materials for energy storage applications

Three water-dispersable composites have been synthesized by in situ chemical oxidative polymerization of aniline N-propanesulfonic acid (AnS) in reduced graphene oxide (r-GO) dispersion, in an ice bath at 0 degrees C and in the absence of any surfactant. The mass ratio between r-GO and aniline monomer have been established as (m(r-GO):m(AnS)) = 1:1, 1:2 and 1:5 while in the composites, the mass ratio between r-GO and polyaniline was found: 1:0.3, 1:0.5 and 1:1, respectively. The molecular structure, morphology, and optical properties of the composites were analyzed through Fourier transform infrared (FTIR), Raman and ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Electrochemical performances for energy storage were evaluated by cyclic voltammetry and galvanostatic charge/discharge measurements with 1M H2SO4 as electrolyte in a three-electrode cell. The composite with the mass ratio (m(r-GO):m(PAnS)) = 1:1 has showed good capacitive behavior with a specific capacitance of 1019 F/g at scan rate of 1 mV/s calculated from integrated area of cyclic voltammogram curve and a retention life of 80% after 100 cycles. These results indicate that the composites prepared by chemical oxidative polymerization are promising materials for electrode supercapacitors.