Nitrogen-doped hollow carbon spheres with enhanced electrochemical capacitive properties

Nitrogen-doped hollow carbon spheres (N-HCS) with uniform size have been synthesized via the hydrothermal method using pyrrole as the precursor. After carbonization at 850 °C, the average diameter of N-HCS is ca. 370 nm with shell thickness of ∼15 nm. The electrochemical capacitive behavior of N-HCS was investigated by cyclic voltammetry and galvanostatic charge–discharge method in 1.0 M H2SO4 aqueous solution. Results show that N-HCS have high specific capacitance (345.2 F g−1 at 0.2 A g−1) and high-rate capability with the increase of the scan rate from 10 to 1000 mV s−1 due to the synergetic effects of the unique hollow nanostructure and the N-doped thin carbon shell. In addition, the capacitance retains 98.1% after 1500 cycles even at a high loading current density of 10 A g−1.