Effect of the electrochemical oxidation/reduction cycle on the electrochemical capacitance of graphite oxide

Reduction largely affects the properties of graphene oxide (GO), because the content of each functional group changes by the oxidation degree. So far no study about re-oxidation and re-reduction of GO has been carried out. Herein, we report the effects of oxidation/reduction cycle of graphite oxide (GtO, multilayered GO) on its composition and electrochemical capacitance property. Electrochemical oxidation and reduction of glassy carbon (GC) were conducted at potentials of +2.0 and −1.1 V (vs. Ag/AgCl), respectively, and then the electrochemical capacitances were measured. According to X-ray photoelectron spectroscopy (XPS) analysis, CC bonds were produced from CH defects of the reduced graphite oxide (rGtO) by the electrochemical re-oxidation. The conductivities of the reduced samples, with CH defects, and re-oxidized samples, with newly produced CC bonds, were high and low, respectively. The high electrochemical capacitance observed for the rGtO electrodes is caused by the activity of the CH defects and good conduction.