Study of the growth mechanism of WS2 nanotubes produced by a fluidized bed reactor

Metal dichalcogenide nanotubes and in particular those Of WS2 were shown to exhibit some unique physical and chemical properties, which offer numerous applications for this kind of nanophase material. Using a fluidized bed reactor (FBR), WS2 nanotubes were obtained in substantial amounts recently, rendering a systematic study of their properties possible. The FBR synthesized nanotubes are multiwalled (5-7 layers); open-ended; long (<0.5 mm), and with diameters of 15-20 nm. They are therefore distinguishable from the previously reported WS2 nanotubes which were shorter, bulkier and with closed ends. Careful analysis by various electron microscopy techniques is used in the present study to shed some light on the growth mechanism of these newly synthesized nanotubes. The proposed growth mechanism model differs markedly from the previously reported mechanisms of formation of both fullerene-like WS2 nanostructures and inorganic nanotubes of WS2.