▎ 摘　　要

Nitrogen-doped graphene hollow spheres (NGHS) have been prepared by a simple layer-by-layer assembly of graphene oxide (GO) and polyaniline (PANI) on polystyrene (PS) nanospheres, followed by calcination to remove the PS template and realize the carbonization of PANI. The resultant NGHS has a high nitrogen content of 8.7 atom%, in which various nitrogen species, such as pyridinic-N, pyrrolic-N, and quaternary-N, are detected. The hollow nanostructure of NGHS can provide high electroactive regions, while the effective nitrogen-doping of graphene can increase electron mobility and space charge capacitance. The specific capacitance of NGHS with four bilayers (NGHS-4bi) can reach 381 F g(-1) at a current density of 1 A g(-1). The greatly enhanced electrochemical performance can be ascribed to the synergistic effect of the hollow nanostructure and nitrogen-doping, suggesting that NGHS as novel electrode materials may have potential applications in high performance energy storage devices. (C) 2013 Elsevier B.V. All rights reserved.