Investigation of the charge-storage behavior of electrochemically activated graphene oxide on supercapacitor electrodes in acidic electrolyte

Herein, charge storage behavior of graphene oxide electrode was investigated after its electrochemical activation. X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), galvanostatic chargedischarge method (GCD), and electrochemical impedance spectroscopy (EIS) were employed for this analysis. From XPS analysis, a decrease of atomic ratio of C=C bond was observed after electrochemical activation from 86.94 to 79.64%. Also, enhancement of specific capacitance appeared from 54.1 to 65.7 F g −1 at 20 mV s −1 , and rectangular shape in CV became more collapsed in activated grapheme oxide electrode. In the GCD profiles, similarly, difference of resistance values at high and low cut-off potential became larger after activation, indicative of increased polarization. From EIS, detailed resistance components were compared, which reflected that the increased resistance and higher capacitance after activation was probably attributed to larger amount of surface functional groups after activation.