The electrochemical performances of the fabricated electrodes were assessed in a threeelectrode cell arrangement using 2 M KOH electrolyte. The pure CN, CCN, VO, CN/VO, and CCN/VO electrodes exhibited the specific capacitance of Electrochemical characteristics of CNQ/GH nanocomposite electrode was investigated using a three-electrode configuration in 6 M aqueous KOH electrolyte. The GCD curves of nanocomposite electrodes showed a higher specific capacitance of 243.2 F g -1 at 0.2 A g -1 , confirming the beneficial synergistic effect between CNQDs and GH. Flexible solid-state symmetric supercapacitor device was fabricated using the prepared nanocomposite electrode, and delivered a high energy density of 22.5 W h Kg -1 at a power density of 250 W Kg -1 with a cycling stability capacitance retention of 89.5% after 15000 cycles.