Performance improvement of N-doped carbon ORR catalyst via large through-hole structure.

N-doped carbon-based materials are crucial electrically conductive additives and non-metal electrocatalysts for the oxygen reduction reaction. At present, many pieces of research are focused on the effects of micropore, mesopore and hierarchical pore structure on the catalytic activity, however, there are few works concerning the role of large-dimension through-hole structure. Hence, in this work, we prepare two kinds of carbon materials with large through-hole structure, i.e. N-doped carbon hollow-spheres and hollow-tubes, as the oxygen reduction catalysts. The synthesis follows template-free morphology-controlled pyrolysis, which is more convenient than the preparation of conventional N-doped nanotubes and graphene. The resultant N-doped carbon hollow-spheres and hollow-tubes evidently enhanced their ORR catalytic activity, remarkable long-term stability and methanol resistance. The large-dimension through-hole structure is found to account for the increase in mass transfer.