Carbon materials with pseudocapacitive performance have attracted emerging interest in the energy storage and conversion field. Reduced graphene oxide (r-GO) with superior conductivity and electrochemical stability has been extensively investigated as an efficient capacitive electrode material. In this study, three-dimensional carbon dots (CDs)@r-GO hydrogel electrode was successfully in situ prepared by the one-pot method, where the CDs play a critical role in serving as both reduction agent and electrochemical active sites. With prolonged reaction time, the oxygen content of the CDs@r-GO nanocomposite material could be effectively reduced to ensure better electric conductivity, and the nitrogen content, which provides pseudocapacitance, was gradually increased. The representative two pairs of fast and reversible current peaks appeared in cyclic voltammetry curves, with around three times higher specific capacitance of CDs@r-GO hydrogel electrode (290 F g-1 at the current density of 1 A g-1 in 1 M H2SO4 electrolyte). This simple and mild approach is promising and it is believed it will shed more light on the preparation of high-efficiency and high-performance energy storage materials based on functional reductive CDs.
Keywords: carbon dots; nitrogen-doping; pseudocapacitance; reduced graphene oxides.