MgO-catalyzed growth of N-doped wrinkled carbon nanotubes

We report a MgO-catalyzed growth of N-doped carbon nanotubes (N-CNTs) that are constructed by graphene layers with wrinkles. Introducing NH3 to a chemical vapor deposition process and keeping a high reaction temperature (∼900 °C) are key factors to the N-CNT growth from MgO. Without N-doping or at a lower temperature, only graphene sheets deposited on MgO surfaces were obtained. Compared to the Fe-catalyzed N-CNTs, the MgO-catalyzed N-CNTs have larger diameters, thinner walls, more surface wrinkles and open ends with polygonal graphene edges. Because carbon dissolves into MgO in a very limited amount, the structural defects and broken sites formed in the graphene layers due to N-doping might have contributed to the formation of new graphene layers and thus lead to the growth of the wrinkled tubes.