Diffusion-Driven Formation of MoS2 Nanotube Bundles Containing MoS2 Nanopods

MoS2 nanotube bundles, along with embedded nested fullerenes, were formed in a gas-phase reaction of molybdenum carbonyl and H2S gas with the assistance of I-2. The amorphous Mo-S-I precursor particles obtained by quenching a modified metal organic chemical vapor deposition (MOCVD) reaction in a large temperature gradient were annealed at elevated temperature in an inert atmosphere. Under the influence of the iodine, the amorphous precursor formed a surface film with an enhanced mobility of the molybdenum and sulfur components. Point defects within the MoS2 layers, combined with the enhanced surface diffusion, lead to a scrolling of the inherently unstable MoS2 lamellae. The role of the reaction temperature on the final structure and morphology of the nanotubes, and also the annealing temperature, were studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). In order to determine the role of iodine as a chemical transport agent, the reaction was carried out in the absence of iodine and with half the amount of iodine. The resulting structures were characterized by scanning electron microscopy (SEM).