Characteristics of graphene-layer encapsulated nanoparticles fabricated using laser ablation method

Graphene layer-encapsulated Ni nanoparticles with diameters between 3 and 10 nm were fabricated by laser ablation techniques and deposited directly on the Si substrate at room temperature. It was found from the field-emission type scanning electron microscopy (FE–SEM) and transmission electron microscopy(TEM) analyses that any carbon nanotubes were not fabricated in the deposited nano-materials. High-resolution TEM observation showed the core-shell structure of Ni–C particles with crystalline nickel core surrounded by graphite-like layers. The X-ray diffraction(XRD) pattern also revealed that nanoparticles embedded in graphene capsules are crystalline nickel. With these Ni–C nanoparticles, we demonstrated the growth of vertically aligned carbon nanotubes with low spatial density on a silicon substrate by thermal CVD.