Graphitic carbon nitride nanosheets made by different methods as electrode material for supercapacitors

In this work, we have synthetized graphitic carbon nitride (g-C3N4) nanosheets by chemical oxidation method and thermal oxidation method. The properties of the prepared g-C3N4 nanosheets were analyzed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM), and their electrochemical performance were further investigated using cyclic voltammetry (CV), electrochemical impedance spectrometry (EIS), and chronopotentiometry (GCD). The g-C3N4, the g-C3N4 after oxidation, and the g-C3N4 after thermal oxidation show different electrochemical properties. More importantly, the specific capacitance of g-C3N4 nanosheets after thermal oxidation of 580 degrees C (170.1 F g(-1)) is higher than g-C3N4 (127.7 F g(-1)) and g-C3N4 after 12 M sulfuric acid (133.6 F g(-1)) at a current density of 0.5 A g(-1). And an excellent cyclic stability was obtained with a capacity retention of approximately 95.9% after 1000 cycles in a 2 M KOH solutions. Further, g-C3N4 nanosheets after thermal oxidation of 580 degrees C show good energy density of 3.740 wh/kg and power density of 99.46 w/kg characteristics superior application potential for high performance energy storage devices.