Synthesizing nano particles of IF- WS2

Following the discovery of carbon fullerenes and nanotubes, the first closed-cage non-carbon fullerene-like nanoparticles and nanotubes ofWS2 were reported by Tenne and co-workers in 1992 [1], followed by MoS2 [2]. Among these IFs, transition metal sulfides (IF-MS2) are of greater interest and they have been investigated extensively. With excellent physical and chemical properties, IF-MS2 nanomaterials have important applications as superior solid lubricants [3], electron devices [4], catalysts [5], hydrogenstorage bodies [6], super shock absorbers [7], photosensitive films and tips for scanning microscopy [8]. Particularly in the field of lubrication, ultralow-friction properties have been observed when IF-MS2 materials were used as solid lubricants [9,10,11]. The reaction of WO3 and S at temperatures higher than 300c in an argon atmosphere provides a convenient and effective method for the synthesis of WS2 nanocrystalline substances. WS2 nanotubes and fullerene-like nanoparticles have been obtained by the reaction at 850 _C under well-controlled conditions. The influences of reaction temperature and duration were carefully investigated in this search. All of the nanostructures were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM)