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Alla Zak

Alla Zak

Holon Institute of Technology, Israel

Title: Single wall and multiwall WS2 nanotubes’ synthesis and characterization - the update


Biography: Alla Zak


The discovery of inorganic nanotubes (INT) of layered transition metal dichalcogenides (MoS2 and WS2) more than two decades ago opened the new research field in a solid state chemistry and in nanomaterials science. However, wide investigation of their properties and applications require the preparation of pure phase powders and in significant amounts. Careful study of the growth mechanism of WS2 multiwall nanotubes (MWINT) resulted in pure phase INTs production and suggested their simple scaling up. The obtained nanotubes are of 30–170 nm in diameter and 5-25 micron in length, of perfect crystallinity and needle-like morphology.

In addition, we have demonstrated that single- to triple-wall WS2 nanotubes (SWINT), of 3-7 nm in diameter and 20-200 nm in length, can be produced by high-power plasma irradiation of big multiwall WS2 nanotubes. Being of single or few-layers wall width these nanotubes promise to be of unusual electro-optical characteristics, which are under study nowadays. Very similar in their properties, the MoS2 and WS2 compounds demonstrate significantly different behavior during their synthesis from corresponding oxides through gas-phase high temperature reaction. Instability of precursor MoOx against reduction in high temperature processes makes INT-MoS2 production very challenging and become an obstacle in the way of their reproducible preparation during these years. Finally, we can report on the reproducible, catalyst free and aspect ratio controlled synthesis of MoS2 inorganic nanotubes (INT) from molybdenum oxide. The obtained nanotubes are of 10-20nm, 40-80 nm or 100-300 nm in diameter, and lengths - up to tens of microns, depends on reaction parameters. INT of MoS2 are both 40% lighter and 40% stronger compared to the analogous WS2 nanoparticles and hence more beneficial for tribological and composite applications. Being semiconductors, both MoS2 and WS2 nanotubes are good candidates for photovoltaics and optoelectronics.


Recent Publications :

  1. O. Grinberg, S. Deng, E. Zussman, T. Livneh and A. Zak, (2016), Raman scattering from single WS2 nanotubes embedded within stretched PVDF electrospun  fibers , sub.
  2. K. R. O’Neal, J. G. Cherian, A. Zak, R. Tenne, Z. Liu, and J. L. Musfeldt, (2016), High Pressure Vibrational Properties of WS2 Nanotubes, Nano Lett. 16, 993−999.
  3. V. Brüser, R. Popovitz-Biro, A. Albu-Yaron, T. Lorenz, G. Seifert, R. Tenne and A. Zak, (2014), Single- to Triple-Wall WS2 Nanotubes Obtained by High Power Plasma Ablation of WS2 Multiwall Nanotubes, Inorganics 2, 177-190.
  4. A. Zak, L. Sallacan Ecker, N. Fleischer and R. Tenne, (2011), Large-Scale Synthesis of WS2 Multiwall Nanotubes and their Dispersion, an Update, Sensors & Transducers Journal 12, 1-10.

5.   M. Shneider, L. Rapoport, A. Moshkovich, H. Dodiuk, S. Kenig, R. Tenne and A. Zak, (2013), Tribological Performance of the Epoxy-Based Composite Reinforced by WS2 Fullerene-Like Nanoparticles and Nanotubes, Phys. Status Solidi A 210, 2298–2306.