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Volume 5, Issue 5
Res. Rev. J Mat. Sci. 2017
ISSN: 2321-6212
Advanced Materials 2017
September 07-08, 2017
Page 24
conference
series
.com
September 07-08, 2017 | Edinburgh, Scotland
Advanced materials & Processing
11
th
International Conference on
Alla Zak, Res. Rev. J Mat. Sci. 2017, 5:5
DOI: 10.4172/2321-6212-C1-004
Single wall and multiwall WS
2
nanotubes synthesis and characterization - The update
T
he discovery of inorganic nanotubes (INT) of layered transition metal dichalcogenides (MoS
2
and WS
2
) 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 WS
2
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 WS
2
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
WS
2
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 MoS
2
and WS
2
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-MoS
2
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 MoS
2
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 MoS
2
are both 40% lighter and 40% stronger compared to the analogous WS
2
nanoparticles and hence
more beneficial for tribological and composite applications. Being semiconductors, both MoS
2
and WS
2
nanotubes are good
candidates forphotovoltaics and optoelectronics.
Biography
Dr. Alla Zak is a Head of the Laboratory for Synthesis and Investigation of Nanomaterials and Senior Lecturer in the Faculty of Science in the HIT-Holon Institute of
Technology, Israel. She is also a Scientific Adviser in the Department of Materials and Interfaces in Weizmann Institute of Science (WIS), Israel. She has made a major
contribution to the study of the growth mechanism and scaling-up of the fullerene-like (IF) nanoparticles of WS
2
and the inorganic nanotubes (INT) of WS
2
and MoS
2
. The
IF-WS
2
nanoparticles are now fully commercialized as superior solid lubricants. Furthermore, she was among the early researchers to show the importance of the WS
2
nanoparticles and nanotubes as reinforcing elements in polymer nanocomposites.
alzak@hit.ac.ilAlla Zak
Holon Institute of Technology, Israel
Figure:
SEM micrograph of INT-WS2, insert – TEM image.