Novel surfactant-stabilized graphene-polyaniline composite nanofiber for supercapacitor applications

In this work, we present a new synthesis method for surfactant stabilized graphene (SSG) combined with polyaniline nanofiber (PANI-Nf) and apply the composite material as supercapacitor (SC) electrodes by screen-printing technique. Surfactant stabilized graphene polyaniline nanofiber composite (PANI-SSG) was synthesized by electrolytic exfoliation of graphite and subsequent interfacial polymerization. Firstly, graphite was electrolytically exfoliated in an electrolyte containing anionic surfactant. Next, ammonium peroxydisulfate initiator and hydrochloric acid were added to the graphene dispersion to form the aqueous phase for interfacial polymerization of polyaniline nanofiber. This dispersion was then added to the water-insoluble solvent phase containing aniline monomer. The polymerization only occurred at the interface of the two immiscible phases leading to polyaniline nanofiber decorated graphene structures. Characterizations by scanning electron microscopy, transmission electron microscopy, atomic force microscopy and Raman spectroscopy suggested nanocomposite formation with intermolecular π-π bonding of graphene with polyaniline nanofibers. Pastes of the materials were screen printed on stainless steel current collectors and tested for SC performance by cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) measurements with 2 M H₂SO₄ electrolyte using a home-built two-electrode test-cell. CV results showed redox peaks of polyaniline with wide cyclic loop, indicating large pseudocapacitance of the nanocomposite. From GCD measurement, a high specific capacitance of 690 Fg⁻¹ at 1 Ag⁻¹ was achieved. Therefore, PANI-SSG nano-composite prepared by electrolytic exfoliation and interfacial polymerization is a promising candidate for SC applications.