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Nanotubes

Our company is synthetizing innovative and patent protected nanomaterials based on molybdenum sulfides and oxides. 

Synthetizised materials, it’s aplication and publications about them are availible on that site.

If you need our materials research or for semi-industrial testing, or you have additional questions and suggestions, please contact us.

 

MoS2 nanotubes

We synthesise the MoS2 peapods-spherical MoS2 nanoparticles grown in the confined geometry of MoS2 nanotube reactors. The nanotubes serve in two roles: as nanoreactors and afterwards as nanocontainers, which prevent undesired release of nanoparticles into atmosphere. Due to very thin walls, which break under short ultra sound agitation, the fullerene-like particles can be released in a control way. This special morphology answers many current questions regarding safe production, storage and transport of nanoparticles. Completely new and relatively simple synthesis can be upgraded for bulk production of a wide variety of inorganic peapods, while the already established industrial production of MoS2 nanoparticles give hope for a prompt applications of MoS2 peapods.

MoS2 mama-tubes

We synthesise the MoS2 peapods-spherical MoS2 nanoparticles grown in the confined geometry of MoS2 nanotube reactors. The nanotubes serve in two roles: as nanoreactors and afterwards as nanocontainers, which prevent undesired release of nanoparticles into atmosphere. Due to very thin walls, which break under short ultra sound agitation, the fullerene-like particles can be released in a control way. This special morphology answers many current questions regarding safe production, storage and transport of nanoparticles. Completely new and relatively simple synthesis can be upgraded for bulk production of a wide variety of inorganic peapods, while the already established industrial production of MoS2 nanoparticles give hope for a prompt applications of MoS2 peapods.

MoO3-x nanowires and nanotubes

Molybdenum trioxide, MoO3, belongs to transition metal oxides that are semiconductors with a wide energy band gap. Because of their structural, optical and electronic properties, these materials are used in numerous fields; in photovoltaics, gas sensing, photo- and electro-chromic applications, as supercapacitors, in field emission devices and for intercalation of lithium or hydrogen ions. Additionally, MoO3 was shown efficient in applications that benefit from its antibacterial properties and reacting with sulphur from anti-wear additives the MoO3 is efficient low-friction additive. We synthesized polycrystalline MoO3-x nanowires and nanotubes. They appear bluish, which is a known indication of oxygen deficiency for molybdenum oxides, which increases their electric conductance dramatically. They crystallize in the orthorhombic structure. Size of these nanowires and nanotubes is very small.

 

TECHNOLOGY

Foreseen application in industry: MoS2 nanotubes as low friction additives to oils, greases or polymers

Use of MoS2 in lubricants is known for decades. Advantage of tubular structure with respect to MoS2 platelets is in in-built exfoliation of nanotubes’ walls into thin cylinders with thickness of 10 nm. This facilitates exfolaitaion of the material under load, reduce or completely eliminate running-in peak (M. Kalin, Tribol.Online 7 (2012 ) 112). In the last 4 years, we have tested friction and wear properties of MoS2 nanotubes in collaboration with experts in the field of tribology from Slovenia and abroad. The article (M. Kalin et al, Tribology Letters 55 (2014) 381) reported that the addition of MoS2 nanotubes in PAO oil reduced the friction coefficient of the steel for 65% and of the diamond-like coating (DLC) for 40%, especially in the boundary lubrication regime. The article (J.Kogovšek et al, Tribology International 61, 40 (2013)) reported that surface roughness had no effect on friction when we added MoS2 into PAO oil: friction coefficient (0.06) was the same regardless on the surface roughness of Ra: 0.006 µm or Ra: 0.04 µm. This is important, because costly final polishing is no longer necessary, if the MoS2 nanotubes are added to a lubricant. This enables substantial savings in the mechanical processing of metals. Comparative tests with conventional MoS2 platelets, which were added to PAO oil was performed on CrN, TiN and TiAlN hard coatings, where in all cases, the nanotubes substantially decreased friction (on CrN for 55%, on TiN for 65%, and on TiAlN for 25%), while the platelets were less efficient. In some cases, the the platelets even worsen the tribological results, for example, they increased the coefficient of friction on TiN for 10%, and increased wear of the uncoated steel for more than 3 times. All results indicate that nanotubes effectively reduce friction in all cases better than platelets of the same compound (Paskvale S. et al., Wear 352-353 (2016) 72). Another important question is whether MoS2 adequately improve the tribological properties of formulated oils with anti-wear and anti-corrosion additives. This was investigated in cooperation with a specialized institute from Austria (AC2T Research GmbH, Wiener Neustadt). When MoS3 nanotubes were added into PAO oils containing anti-wear additive zinc dialkyl dithiophosphate (ZDDP) in a few wt.% friction was further reduced for 50% and wear for 10%. (A. Tomala et al., Tribol Lett (2015) 59:26).

PUBLICATIONS

Publications originate from research work at the Jozef Stefan Institute

Structural properties of MoS2 & tribology testing using MoS2 nanotubes in PAO oils

  1. TOMALA, A., RODRÍGUEZ RIPOLL, Manel, GABLER, C., REMŠKAR, Maja, KALIN, Mitjan. Interactions between MoS2 nanotubes and conventional additives in model oils. Tribology International 2017, vol. 110, p. 140-150, doi: 10.1016/j.triboint.2017.01.036.

  2. PASKVALE, Srečko, REMŠKAR, Maja, ČEKADA, Miha. Tribological performance of TiN, TiAlN and CrN hard coatings lubricated by MoS2 nanotubes in olyalphaolefin oil. Wear 2016, vol. 352-353, p. 72-78, doi: 10.1016/j.wear.2016.01.020.

  3. TOMALA, A., VENGUDUSAMY, B., RODRÍGUEZ RIPOLL, Manel, NAVEIRA SUAREZ, M., REMŠKAR, Maja, ROSENTSVEIG, Rita. Interaction between selected MoS2 nanoparticles and ZDDP tribofilm. Tribology Letters 2015, vol. 59, p. 26-1-26-18, doi: 10.1007/s11249-015-0552-z.

  4. KALIN, Mitjan, KOGOVŠEK, Janez, KOVAČ, Janez, REMŠKAR, Maja. The formation of tribofilms of MoS [sub] 2 nanotubes on steel and DLC-coated surfaces. Tribology Letters 2014, vol. 55,p. 381-391, doi: 10.1007/s11249-014-0366-4.

  5. KOGOVŠEK, Janez, REMŠKAR, Maja, MRZEL, Aleš, KALIN, Mitjan. Influence of surface roughness and running-in on the lubrication of steel surfaces with oil containing MoS2 nanotubes in all lubrication regimes. Tribology international 2013, vol. 61, p. 40-47, doi: 10.1016/j.triboint.2012.12.003.

  6. KOGOVŠEK, Janez, REMŠKAR, Maja, KALIN, Mitjan. Lubrication of DLC-coated surfaces with MoS2 nanotubes in all lubrication regimes : surface roughness and running-in effects. Wear 2013, vol. 303, p. 361-370, doi: 10.1016/j.wear.2013.03.033.

  7. KALIN, Mitjan, KOGOVŠEK, Janez, REMŠKAR, Maja. Nanoparticles as novel lubricating additives in a green, physically based lubrication technology for DLC coatings. Wear 2013, vol. 303, p. 480-485, doi: 10.1016/j.wear.2013.03.009.

  8. JELENC, Janez, REMŠKAR, Maja. Friction on a single MoS2 nanotube. Nanoscale Research Letters 2012, vol. 7, p. 208-1-208-17, doi: 10.1186/1556-276X-7-208.

  9. KALIN, Mitjan, KOGOVŠEK, Janez, REMŠKAR, Maja. Mechanisms and improvements in the friction and wear behavior using MoS2 nanotubes as potential oil additives. Wear 2012, vol. 280/281, p. 36-45, doi: 10.1016/j.wear.2012.01.011

  10. REMŠKAR, Maja, MRZEL, Aleš, VIRŠEK, Marko, GODEC, Matjaž, KRAUSE, Matthias, KOLITSCH, Andreas, SINGH, Amol, SEABAUGH, Alan. The MoS2 Nanotubes with defect-controlled electric properties. Nanoscale Research Letters 2011, vol. 6, article number 26, 7 str., doi: 10.1007/s11671-010-9765-0

  11. REMŠKAR, Maja, VIRŠEK, Marko, MRZEL, Aleš. The MoS2 nanotube hybrids. Applied Physics Letters 2009, vol. 95, p. 133122-1-133122-3.

  12. REMŠKAR, Maja, MRZEL, Aleš, VIRŠEK, Marko, JESIH, Adolf. Inorganic nanotubes as nanoreactors: the first MoS2 nanopods. Advanced Materials 2007, vol. 19, p. 4276-4278

  13. Paletti, P., Fathipour, S., Remškar, M., & Seabaugh, A. (2020). Quantitative, experimentally-validated, model of MoS2 nanoribbon Schottky field-effect transistors from subthreshold to saturation. Journal of Applied Physics, 127(6), 065705. doi:10.1063/1.5127769 

  14. Reinhardt, S., Pirker, L., Bäuml, C., Remškar, M., & Hüttel, A. K. (2019). Coulomb Blockade Spectroscopy of a MoS2 Nanotube. Physica Status Solidi (RRL) – Rapid Research Letters. doi:10.1002/pssr.201900251

  15. Kazanov, D. R., Poshakinskiy, A. V., Davydov, V. Y., Smirnov, A. N., Eliseyev, I. A., Kirilenko, D. A., … Shubina, T. V. (2018). Multiwall MoS2 tubes as optical resonators. Applied Physics Letters, 113(10), 101106. doi:10.1063/1.5047792