High-surface-area nitrogen-doped reduced graphene oxide for electric double-layer capacitors

A two-step method consisting of solid-state microwave irradiation and heat treatment under NH₃ gas was used to prepare nitrogen-doped reduced graphene oxide (N-RGO) with a high specific surface area (1007 m²g^-1), high electrical conductivity (1532 Sm^-1), and low oxygen content (1.5 wt%) for electrical double-layer capacitor applications. The specific capacitance of N-RGO was 291 Fg^-1 at a current density of 1 Ag^-1, and a capacitance of 261 Fg^-1 was retained at 50 Ag^-1, which indicated a very good rate capability. N-RGO also showed excellent cycling stability and preserved 96% of the initial specific capacitance after 100000 cycles. Near-edge X-ray absorption fine-structure spectroscopy results provided evidenced for the recovery of π conjugation in the carbon networks with the removal of oxygenated groups and revealed chemical bonding of the nitrogen atoms in N-RGO. The good electrochemical performance of N-RGO is attributed to its high surface area, high electrical conductivity, and low oxygen content. Between the sheets: Nitrogen-doped reduced graphene oxide (N-RGO) shows excellent electrochemical performance and stability as an electrode material for electrical double-layer capacitors due to its high surface area and electrical conductivity. The two-step synthesis incorporates nitrogen into the hexagonal carbon lattice and restores π conjugation.