Template Synthesis of Near-Monodisperse¹Microscale Nanofibers and Nanotubules of MoS₂

Abstract

Near-monodisperse microscopic nanostructures of MoS 2 were prepared by thermal decomposition of two different ammonium thiomolybdate molecular precursors, (NH 4 ) 2 MoS 4 and (NH 4 ) 2 Mo 3 S 13, within the confined voids of a porous aluminum oxide membrane template. Our low-temperature (450 °C) synthetic route yielded large quantities of hollow tubules of MoS 2 of uniform size and shape that were ∼30 μm long with diameters of 50 nm and wall thicknesses of about 10 nm. More irregularly shaped, mainly solid fibers of MoS 2 with diameters of about 200 nm were synthesized by changing the template to one with larger pores. The morphology of the fibers or tubules was studied with respect to the choice of precursor, the characteristics of the precursor solutions, the incorporation methods, the template characteristics, and the heat treatment during firing. The MoS 2 structures were characterized by scanning and transmission electron microscopies, energy dispersive spectroscopy, electron and X-ray diffraction, and optical absorption spectroscopy. This template-assisted growth process yielded large quantities of MoS 2 tubules or fibers that could be isolated from the template. However, under the growth conditions studied, the formation of H x MoS 2 “bronzes” could not be discounted.