Nitrogen-doped graphene/palladium nanoparticles/porous polyaniline ternary composite as an efficient electrode material for high performance supercapacitor

Abstract

In the proposed study porous PANI has been prepared by polymerization using brine solution, which significantly improved its electrochemical response. The resultant porous PANI provides larger effective surface area responsible for its better supercapacitor performance. In this article, a ternary composite of nitrogen doped graphene-palladium nanoparticles-porous polyaniline (N-GNS-PdNP-PANI) has been synthesized by two step approach. The resultant material was characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). The electrochemical measurements of the materials were carried out in 1 M H2SO4 employing electrochemical techniques such as cyclic voltammetry (CV), Galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The electrochemical study demonstrated high specific capacitance (Csp) of 935 F g−1 at scan rate of 0.1 V s−1 for N-GNS-PdNP-PANI. A symmetric supercapacitor device was fabricated based on N-GNS-PdNP-PANI and it delivered specific capacitance of 230 F g−1. It exhibits high energy density and power density of 31.94 Wh kg−1 and 1.2 kW kg−1 respectively. Remarkably, the electrode material shows good charge–discharge rate capability and retains over 88% of capacitance as the current density increases from 3.8 to 15 A g−1. It is noteworthy that the electrode retains 96% of its initial capacitance after 3000 cycles at a current density of 3.8 A g−1. This hybrid composite possesses many ion-accessible sites, interconnected porous network and high mechanical strength, resulting in high specific capacitance, superior cycle stability and excellent rate performance. By virtue of its outstanding characteristics, N-GNS-PdNP-PANI synthesized by proposed economical method will gain promising applications in the field of supercapacitors. Keywords: Porous polyaniline, N-doped graphene, PdNP, High specific capacitance