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 Ag-1, the specific capacitance of 3D-AGE is 258.2 Fg(-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 Fg(-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. (C) 2019 Elsevier Ltd. All rights reserved.