Novel three-dimensional N-doped interconnected reduced graphene oxide with superb capacitance for energy storage

Here, we report on the nitrogen doping of different graphene-based nanomaterials, namely two-dimensional (2D) graphene oxide (GO) and three-dimensional (3D) interconnected reduced graphene oxides (ICrGO), for energy storage. For N-doping, a facile hydrothermal approach was employed using ammonium fluoride (NH4F) as the precursor to synthesize 2D N-rGO and 3D N-ICrGO. The fabricated N-doped graphene-based materials were systematically studied using various surface characterization techniques and spectroscopic methods, revealing that the novel 3D N-ICrGO possessed thin transparent sheets and a highly interconnected graphene structure with moderate defect sites and that the N-doping of the graphene structure could be effectively controlled through the appropriate amount of NH4F within the precursor solutions. The energy storage performance of the 2D and 3D nanomaterials was determined using cyclic voltammetry and chronopotentiometry, showing that the novel N-ICrGO exhibited much higher specific capacitance in contrast to the N-rGO, ICrGO, and GO. The specific capacitance of N-ICrGO at 2.0 Ag-1 was determined to be 262 Fg(-1), which was over 4.4 times higher than that of N-rGO (60 Fg(-1)). Furthermore, the N-ICrGO exhibited an excellent rate capability and high cycling stability, with <5% decay over 2400 cycles in symmetric capacitor, promising for advanced energy storage applications. This study demonstrates that the unique 3D structure of ICrGO and the N-doping greatly enhance the overall energy storage performance of graphene-based nanomaterials.