Nanoporous nitrogen-doped graphitic carbon hollow spheres with enhanced electrochemical properties

The integration of a high atomic percentage (at%) of nitrogen atoms into a graphitic carbon framework is an important issue because of the advantages in improving the functions of nanocarbon materials. Nanoporous graphitic nitrogen-doped carbon hollow spheres are prepared via the direct pyrolysis of nanostructured conducting poly(N-methylaniline) (PNMA) at high temperatures. The synthesized nanocarbon shows up to 8.9 at% doped nitrogen and a high specific surface area of up to 545.1 m2 g−1. The as-prepared nitrogen-doped carbon shows effective oxygen reduction reaction (ORR) activity with a prominent cathodic peak potential of 0.72 V versus a reversible hydrogen electrode (RHE), and good positive onset and half-wave potentials of 0.87 and 0.73 V versus RHE, respectively. The nanoporous graphitic carbon hollow spheres also exhibit a very high specific capacitance of 332.4 F g−1 at a current density of 2 A g−1 and 301.8 F g−1 at a scan rate of 10 mV s−1. Moreover, the prepared nanocarbon displays good rate capabilities and no loss of specific capacitance, even after 5000 cycles of charge–discharge experiments.