Furthermore, as shown in Fig. 7a, two-electrode symmetricsupercapacitors were fabricated using functionalized graphenesas anode and cathode materials. Fig. 7b shows CV curves of thesymmetric supercapacitors in a 1 M H2SO4 electrolyte. Therectangular outline of the CV curves (Fig. 7b) shows redox peakswith functionalized graphenes, indicating the presence ofpseudocapacitance aer the electrochemical oxidationprocesses. As shown in Fig. 7c and d, the specic capacitancesof functionalized graphenes are also signicantly increased.Simultaneously, the FG1.3-based symmetric supercapacitordisplays excellent cycling stability: aer cycling at a currentdensity of 20 A g1 for 5000 cycles, the loss of specic