Permeation of Nickel Nanodots on Carbon Nanotubes: Synthesis of 3D CNT-Based Nanomaterials

In this paper, we report the fabrication of three-dimensional (3D) hybrid carbon nanotubes (CNT)-based nanostructures. Secondary carbon nanotubes are grown on the hydrogenated and unzipped horizontal carbon nanotubes without any further catalyst deposition. Hydrogenation of horizontal CNTs leads to out-diffusion of Ni nanoparticles that were trapped within the walls of nanotubes during the original growth process. This out-diffusion effect, as permeation, leads to the formation of nickel dots at the surfaces of carbon nanotubes which acts as the catalyst for the growth of secondary nanotubes. By controlling the secondary growth condition, a variety of 3D structures could be achieved. The permeation effect and the evolution of secondary nanostructures are studied extensively by means of scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analysis