The FGCT exhibited a higher SBET of 21.74 m 2 g -1 with a pore volume of 0.166 cm 3 g -1 , than that of pristine TiO2 spheres (4.47 m 2 g -1 ; 0.022 cm 3 g -1 ), g-C3N4 (5.51 m 2 g -1 ; 0.03 cm 3 g -1 ), CNF (10.95 m 2 g -1 ; 0.053 cm 3 g -1 ). The FGCT material showed the presence of N, and O heteroatom with 16.39, and 32.72 at% through XPS analysis. In a three-electrode system with 4 M KOH electrolyte, the FGCT electrode delivered the specific capacitance of 817 F g -1 at 0.25 A g -1 , and 89.2% capacitance retention upto 2000 cycles. Further, the FGCT electrode showed the energy density of 29.5 W h Kg -1 under a power density of 132.75 W Kg -1 . The high performance of GCT was ascribed to (i) surface function groups that could improve the active sites, and diffusion of ions, (ii) enhanced dispersibility of the carbon and formation of strong chemical reaction that allows improved ion diffusion due to carboxyl functionalization, and