Recently, Gorenskaia et al. fabricated the synthesis of N-doped graphene was carried out by one-step hydrothermal process at 180 °C about 12 h in Ar environment using 3,3',4,4'tetraaminodiphenyl oxide (TADPO) as the precursor of nitrogen . It has been demonstrated that the specific capacitance as well as the content of nitrogen of N-doped graphene enhances with increase in the amount of nitrogen precursor during the synthesis.