Microwave synthesis of nitrogen-doped carbon nanotubes anchored on graphene substrates

We report a fast and facile microwave technique to synthesize nitrogen-doped carbon nanotubes anchored on graphene substrates from azobis(cyclohexanecarbonitrile), a commodity chemical, commonly used as a radical initiator in polymerization reactions as the nanotube precursor. Micrometer-long, nitrogen-doped carbon nanotubes vertically anchored on graphene was obtained to produce mesoporous, hierarchical nanostructures. X-ray photoelectron spectroscopy reveals that nitrogen moieties exist as pyridinic and graphitic nitrogen. When applied as anodes in lithium-ion batteries, our materials exhibit a high capacity of 1342 mA h g−1 even after prolonged cycling reflecting the ability of the three-dimensional network to accommodate the extreme volume changes occurring during the lithiation/delithiation reactions.