Graphene quantum dots doped conducting polymer nanocomposite for high performance supercapacitor application

Water-dispersible graphene quantum dots are synthesised by the hydrothermal method. Graphene quantum dots polypyrrole nanocomposites (PGQDs) are prepared by the chemical oxidation polymerisation method. The properties of the composite were characterised by UV-Visible absorption spectra, transmission electron microscopy, and impedance spectroscopy (temperature from 300 K to 393 K, frequency 20 Hz-1 MHz). The dielectric and modulus parameters were studied and high conductivity of 1.62 S/Cm was observed. A solid-state supercapacitor with a simple structure is designed based on polymer quantum dots composite film using stainless steel electrodes with PVA/KOH gel electrolyte. The performance of the supercapacitor was analysed by using cyclic voltammetry (CV), galvanostatic charge-discharge curves (GCD), and electrochemical impedance spectra (EIS) and Nyquist plot. It was observed that PPY-GQDs supercapacitors exhibited a maximum specific capacitance of 790.3 F/g. The electrochemical properties of the supercapacitor with high flexibility and stability are enhanced by optimising the concentration of electrically conductive substances like polymer gel and an increase in the concentration of GQDs.