Nitrogen-doped hollow carbon spheres for supercapacitors application

Abstract

Highly monodispersed nitrogen-doped hollow mesoporous carbon spheres (N-HMCSs) are prepared through a “silica-assisted” synthetic strategy with cetyltrimethylammonium bromide as cationic surfactant, 3-aminophenol/formaldehyde as carbon and nitrogen sources, tetraethyl orthosilicate as the structure-assistant agent. The particle sizes and shell thicknesses of the N-HMCSs can be easily tuned in the range of 130–290 nm and 17–42 nm, respectively, by simply modifying the ethanol-water volume ratio. The obtained N-HMCSs have high surface areas (750–1006 m2 g−1), large pore volumes (1.01–1.41 cm3 g−1), uniform mesoporous size of ∼3 nm, and high nitrogen loading content of 6.86 wt%. Due to these characteristics, the N-HMCSs exhibit a specific capacitance of 170 F g−1 at a current density of 1.0 A g−1 in 6 M KOH aqueous electrolyte. Besides, the capacitance still remains 94% after 5000 charge/discharge cycle, suggesting excellent cycling stability. The N-HMCSs may show promising prospects as electrode materials for electrochemical capacitors.