Preparation and characterization of multi-walled carbon nanotubes with nickel–phosphorous layers of high magnetic properties

The multi-wall carbon nanotubes (MWNTs) with nickel–phosphorous (Ni–P) layers were prepared by electroless plating method. To obtain the MWNTs with Ni–P layers of high magnetic properties, an effective purification treatment and a pre-treatment procedure were developed. The crude MWNTs, the purified MWNTs and the MWNTs with Ni–P layers were characterized by scanning electron microscope (SEM)/energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). SEM results, TEM images and XRD results indicate that impurities in the crude MWNTs were effectively removed after the purification treatment and a large number of Ni nanoparticles were homogenously coated on the surface of the purified MWNTs. According to the VSM test, the saturation magnetization (Ms) of the MWNTs with Ni–P layers is 91.5 emu/g which is higher than results of other researchers.