One-step preparation of carbon nanotubes with nickel as the core

CNTs with core-shell structure were successfully synthesized by a microwave-assisted polyol method, and magnetic Ni nanoparticles were employed as a catalyst. The preparation method is fast and simple. The structures, morphology and magnetic properties of the as-synthesized samples were investigated using Raman spectrometer, X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), respectively. The XRD results suggested that Ni particles used as a catalyst in our experiment were nano-sized. In this paper, magnetic Ni nanoparticles were employed as a catalyst, and an electric spark on metal Ni nanoparticles with the microwave eddy current effect could induce CNTs’ formation with the further reaction. The length of hollow carbon nanotubes was micro-sized and the diameters of most of the CNTs were varying from 18 to 20 nm according to the TEM images. Magnetic measurements demonstrated that CNTs with core-shell structure indicated a characteristic ferromagnetic behavior compared with Ni nanoparticles.