N-substituted Carboxyl Polyaniline Covalent Grafting Reduced Graphene Oxide Nanocomposites and Its Application in Supercapacitor

Abstract

A novel approach to covalent grafting N-substituted carboxyl polyaniline(NPAN) onto the graphene oxide (GO) is described in this study. In order to carry out this purpose, aniline is bonded to the graphene oxide via the nucleophilic ring-opening reaction of epoxy group of GO, where partial reduction of GO also concomitantly occurred. The reduced graphene oxide modified with aniline (aRGO) further serves as reactivity point for the in-situ polymerization of the N-phenylglycine(NAN) monomer. The covalent grafting aRGO-g-NPAN hybrid is confirmed and characterized by FT-IR, UV-vis, Raman, XRD, XPS and TEM. The analysis indicates that the NPAN is successfully grafted on the surface of aRGO, and exhibits nanorod structure with the diameter of 40–50nm and a length of tens to hundreds of nanometers. Electrochemical tests reveal that the specific capacitance of the aRGO-g-NPAN hybrids is 654.3Fg−1 at 1Ag−1, while the capacitance performances of 418.5Fg−1 for traditional physical mixture, indicating that the covalent grafting hybrids can reduce the interface resistance between aRGO and NPAN polymer to increase the charge transfer in the faradic transformation of NPAN process. Under the successive charge/discharge 1000 cycles, the specific capacitance of aRGO-g-NPAN based capacitor preserves 79.1% of its initial capacitance, while the traditional physical mixture shows 67.4% of its initial capacitance, suggesting the good cycling stability for the aRGO-g-NPAN hybrids.