Nitrogen and sulfur Co-Doped graphene quantum dots decorated CeO2 nanoparticles/ polyaniline: As high efficient hybrid supercapacitor electrode materials

Abstract

Recently, hybrid supercapacitor due to high energy/power density and long cycle life has been attractive field for energy researchers. In this work, we demonstrated the decoration of graphene quantum dots on metal oxide/polyaniline to form efficient electrode materials for a hybrid supercapacitor for the first time. Ultrafine N and S co-doped graphene quantum dots (N,S-GQDs) were grown on CeO2 nanoparticles via in situ hydrothermal method. Then, PANI-N,S-GQDs@CeO2 nanocomposites have been prepared by the chemical oxidation polymerization process. The simultaneous incorporation of S and N species in GQDs provides a larger active surface and greatly increases the contact area with the CeO2 in polymer nanocomposite. The as prepared material was analyzed by spectroscopic techniques and electron microscopy analysis. Electrochemical properties of the PANI-N,S-GQDs@CeO2 as supercapacitor electrodes were investigated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy experiments. The maximum specific capacity of 189 C g−1was obtained for PANI/5 wt % N,S-GQDs@CeO2 nanocomposite at current density of 1 A g−1 in comparison with 175 and 115 C g−1 for PANI/10 wt% N,S-GQDs@CeO2 and PANI/5 wt% CeO2 respectively. Value of specific capacity remained at 75% after 1000 cycles under the current density of 1 A g−1.