Nitrogen and Phosphorous Co-Doped Graphene Monolith for Supercapacitors

The co-doping of heteroatoms has been regarded as a promising approach to improve the energy-storage performance of graphene-based materials because of the synergetic effect of the heteroatom dopants. In this work, a single precursor melamine phosphate was used for the first time to synthesise nitrogen/phosphorus co-doped graphene (N/P-G) monoliths by a facile hydrothermal method. The nitrogen contents of 4.27-6.58at% and phosphorus levels of 1.03-3.00at% could be controlled by tuning the mass ratio of melamine phosphate to graphene oxide in the precursors. The N/P-G monoliths exhibited excellent electrochemical performances as electrodes for supercapacitors with a high specific capacitance of 183Fg(-1) at a current density of 0.05Ag(-1), good rate performance and excellent cycling performance. Additionally, the N/P-G electrode was stable at 1.6V in 1m H2SO4 aqueous electrolyte and delivered a high energy density of 11.33Whkg(-1) at 1.6V.