Bulk Synthesis of Inorganic Fullerene-like MS₂(M = Mo, W) from the Respective Trioxides and the Reaction Mechanism

Abstract

Recently, milligram quantities of MoS2 fullerene-like nanotubes and negative curvature polyhedra (generically called inorganic fullerene-like material, IF), were reproducibly obtained by a gas phase reaction from an oxide precursor (Feldman, Y.; Wasserman, E.; Srolovitz, D. J.; Tenne, R. Science 1995, 267, 222. Srolovitz, D. J.; Safran, S. A.; Homyonfer, M.; Tenne, R. Phys. Rev. Lett. 1995, 74, 1778). The present work focuses on the mechanism of the synthesis of IF-MS2 (M = W, Mo). The IF material is obtained from oxide particles smaller than ca. 0.2 μm, while larger oxide particles result in 2H-MS2 platelets. The key step in the reaction mechanism is the formation of a closed layer of MS2, which isolates the nanoparticle from its surroundings and prevents its fusion into larger particles. Subsequently, the oxide core of the nanoparticle is progressively converted into a sulfide nanoparticle with an empty core (IF). Taking advantage of this process, we report here a routine for the fabrication of macroscopic quantities of a pure IF-WS2 phase with a very high yield. As anticipated, the size distribution of the IF material is determined by the size distribution of the oxide precursor. The present synthesis paves the way for a systematic study of these materials which are promising candidates for, e.g., solid lubrication.

Microwave-assisted synthesis of WS2nanowires through tetrathiotungstate precursors

“…The shift is however lower than reported for the I F-WS 2 nanostructures (i.e. at 649.1 and 551 nm, respectively) [14,45]. Our spectra thus indicate formation of WS 2 hydrothermally synthesized MoS 2 nanowires [46].…”

“…The shift may be attributed to the strain relaxation in the 2H WS 2 crystal lattice due to the formation of curved nanostructures [13,14]. This observation was supported by the calculated cell parameters of the same a (0.31 nm) and somewhat longer c (1.26 nm) compared with those of the 2H WS 2 system (a = 0.31 and c = 1.236 nm; JCPDS card no.…”

“…Tenne et al carried out extensive studies on various layered materials and have been pioneers in the preparation of concentric polyhedra and/or nanotubes of MS 2 (M = Mo and W) layered materials through gas-phase reaction of H 2 S with the respective metal-oxides at elevated temperatures and under reducing atmosphere [11][12][13][14][15]. Production of macroscopic quantities of WS 2 nanotubes had later been reported through modification of the gas-phase reaction, where W/WO x was heated under a mixture of Ar and H 2 S gases [16].…”

Atom by atom: HRTEM insights into inorganic nanotubes and fullerene-like structures

“…When these structures were projected onto a HRTEM image, the measured distances on the image appeared to be continuously increasing or decreasing, although the structures have evenly spaced shells. Therefore, bulk measurements of powder diffraction would lead to more accurate and unambiguous results, as performed previously for onion-like nanoparticles (40). The synthesis process is continuously being improved, and it produces bulk quantities of high yield WS 2 -NT, which enables bulk characterization.…”

Optical Properties of MS2 (M = Mo, W) Inorganic Fullerenelike and Nanotube Material Optical Absorption and Resonance Raman Measurements

“…Subsequently, the largescale synthesis of IF-MS 2 (M Mo, W) powder has been reported. [3][4][5] Furthermore, these IF metal dichalcogenides exhibit a variety of sizes and shapes and have been investigated by x-ray powder diffraction (XRD), 3 scanning tunneling microscopy (STM), 6 high resolution transmission electron microscopy (TEM), [3][4][5] optical absorption spectroscopy, 7 and Raman scattering. 8 The XRD analysis revealed that the bulk 2H structure of the unit cell is locally preserved within an IF particle.…”