3D nitrogen-doped graphene created by the secondary intercalation of ethanol with enhanced specific capacity.

Here, we report an improved synthesis strategy for 3D nitrogen-doped graphene to increase the specific capacity of supercapacitors. Ethanol replaces the strong oxidant hydrogen peroxide in the improved Hummers method, and the loose porous structure is conducive to charge transfer. N-doped porous 3D graphene was synthesized from RGO-C prepared by ethanol secondary intercalation modification of functional groups. Ammonia was selected as the dopant; the microstructure and electrochemical performance of samples synthesized at different temperatures were examined. The results demonstrate that the 3D nitrogen-doped graphene (N-RGO-5) had a layered tuple shape with a sheet thickness of 0.612 nm.The specific surface area of the 3D N-RGO-5, which was prepared at 190°C, was 258.371 m2 g-1, which was higher than that (5.877 m2 g-1) of the original graphite. The 3D N-RGO-5 exhibited a specific capacitance of 236 F g-1 and an energy density of 32.78 W h kg-1 at a current density of 1 A g-1, which is 27% higher than the specific capacitance of RGO. The 3D N-RGO-5 demonstrated an excellent capacity retention rate of 93.6% after 5000 cycles at a current density of 1 A g-1. This study demonstrates that the unique 3D structure and N-doping of N-RGO considerably improved the overall energy storage performance of graphene-based nanomaterials.