Synthesis and characterization of activated 3D graphene via catalytic growth and chemical activation for electrochemical energy storage in supercapacitors

Activated three-dimensional graphene (3D-AGE) powders with high specific surface area have been successfully prepared by combined strategies of catalytic growth and chemical activation for application in supercapacitors. The morphology, structure and composition of 3D-AGE are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen adsorption-desorption and X-ray photoelectron spectroscopy (XPS). The electrochemical performance is evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (GDC) and electrochemical impedance spectroscopy (EIS). The results show that the 3D-AGE exhibits very high specific capacitance and stability as electrode material for supercapacitor in 1 mol L−1 KOH aqueous electrolyte. It is found that at a current density of 1 A g−1, the specific capacitance of 3D-AGE is 258.2 F g−1, which is much higher than the one (87.8 F g−1) of pristine 3D graphene (3D-GE). It is also found that after 2000 charge-discharge cycles, the specific capacitance increases from 285.2 to 345.3 F g−1, with an impressive increment rate of up to 21%. The excellent electrochemical performance of 3D-AGE can be attributed to its unique 3D nanostructure with high surface area, abundant oxygen functional groups, as well as fast ion and electron transport rates.