Supercritical fluid assisted synthesis of N-doped graphene nanosheets and their capacitance behavior in ionic liquid and aqueous electrolytes

N-doped GNS have been prepared by a single step supercritical fluid assisted reaction. They show specific capacitances of 280 F g ⁻¹ in aqueous solution and 104 F g ⁻¹ in ionic liquid with energy densities of 8 W h kg ⁻¹ and 40 W h kg ⁻¹ , respectively.