Synthesis and Characterization of Reduced Graphene Oxide, Metal Oxide/Hydroxide and Polyaniline Nanocomposites for Supercapacitor Application

Abstract

The research thesis entitled “Synthesis and characterization of reduced graphene oxide, metal oxide/hydroxide and polyaniline nanocomposites for supercapacitor application” presents the synthesis, structural characterization and electrochemical characterization of reduced graphene oxide/metal oxide/polyaniline nanocomposites. Two different metal oxides, namely, copper oxide and vanadium pentoxide and a metal hydroxide, namely, nickel hydroxide were used to synthesize three sets of nanocomposites with reduced graphene oxide (rGO) and polyaniline (PANI) by insitu single step chemical methods by varying the weight percentages of each of the constituents. The synthesized nanocomposites were reduced graphene oxide/copper oxide/polyaniline nanocomposites (GCP), reduced graphene oxide/vanadium pentoxide/polyaniline nanocomposites (GVP) and reduced graphene oxide/nickel hydroxide/polyaniline nanocomposites (GNP). The structures of the nanocomposites were characterized by powder-XRD, FT-IR spectroscopy, X-ray photon spectroscopy, energy dispersive spectroscopy, field emission scanning electron microscopy and Raman spectroscopy. The electrochemical characterizations of the synthesized nanocomposites were carried out in a two electrode system, by cyclic voltammetry, galvanostatic charge/discharge studies and electrochemical impedance spectroscopy in the presence of aqueous electrolytes. The magnetic effect to improve the electrochemical performance of antiferromagnetic GNP nanocomposites were also studied under different magnetic fields. The electrochemical results obtained for all the three sets of nanocomposites are highly impressive. Among the three sets of nanocomposites synthesized, the nanocomposite G14NP with a weight percentage composition of rGO14%: Ni(OH)214%: PANI72%, exhibited a highest specific capacitance of 602.40 F g‒1, specific capacity of 722.88 C g‒1, an energy density of 120.48 W h kg‒1 and a power density of 2584.83 W kg‒1 with 1 M sulfuric acid as the electrolyte, at a current density of 1 A g‒1. The G14NP retains 75% of its initial specific capacitance up to 16500 cycles. With one nanocomposite, which exhibited highest electrochemical performance, from each of the three series of nanocomposites, the practical application as secondary power source was demonstrated.