A PROCESS FOR THE SYNTHESIS OF NANOTUBES AND FULLERENE-LIKE NANOSTRUCTURES OF TRANSITION METAL DICHALCOGENIDES, QUASI ONE-DIMENSIONAL STRUCTURES OF TRANSITION METALS AND OXIDES OF TRANSITION METALS

Object of the Invention, Technical Field, to which the Invention belongs

The object of the invention is a process for the synthesis of nanotubes of transition metal dichalcogenides, of fullerene-like nanostructures of transition metal dichalcogenides, of nanotubes of transition metal dichalcogenides, filled with fuHerene-like nanostructures of transition metal dichalcogenides, of quasi one- dimensional structures (nanowires, microwires and ribbons) of transition metal oxides and of quasi one-dimensional structures of transition metal dichalcogenides, consisting of fine crystallites of transition metal dichalcogenides. The invention is in the field of inorganic chemistry and of chemistry of transition metal dichalcogenides. The invention relates to the synthesis of nanotubes of transition metal dichalcogenides, of fullerene-like nanostructures of transition metal dichalcogenides, of nanotubes of transition metal dichalcogenides, filled with fullerene-like nanostructures of transition metal dichalcogenides, of quasi one-dimensional structures (nanowires, microwires and ribbons) of transition metal oxides, and of quasi one-dimensional structures of transition metal dichalcogenides, consisting of fine crystallites of transition metal dichalcogenides, using the method of transformation of quasi one-dimensional compounds with a sub-micron diameter, described by the formula M ₆ C _y H _z , 8.2<y+z<10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te); H is a halogen (I), by heating in the presence of at least one reactive reagent containing a chalcogen, directly or through previous heating in the presence of oxygen, and by the subsequent transformation of quasi one-dimensional metal oxides of transition metals formed by heating in the presence of at least one reactive reagent containing a chalcogen. This process enables the synthesis of nanotubes of transition metal dichalcogenides, of fullerene-like

nanostructures of transition metal dichalcogenides, of nanotubes of transition metal dichalcogenides, filled with fullerene-like nanostructures of transition metal dichalcogenides, of quasi one-dimensional structures of metal oxides of transition metals, and of quasi one-dimensional structures of transition metal dichalcogenides, consisting of fine crystallites of transition metal dichalcogenides.

Technical Problem

Inorganic fullerene-like nanostructures and inorganic nanotubes are interesting owing to special crystallographic morphology and physical characteristics. Under certain conditions they can be synthesized from many inorganic materials, including transition metal dichalcogenides, among which numerous have also a technological use. Thus, for instance MoS ₂ , one of transition metal dichalcogenides is used in catalysis, at desulphurization of oil. In addition, it is classified into the group of solid lubricants, which are used in vacuum technology and space technology and other applications where the use of liquids is limited. The oxides of transition metals are used among others as sensors of different gases, catalyst carriers and as catalysts and cathode material in batteries. For the use in catalysis and elsewhere, when the small size of particles and large active surface is important, a configuration of transition metal dichalcogenides would be desirable, where the MoS ₂ particles with the large active surface would be simultaneously interlinked into structures, enabling simple removing of them from the liquid. Equally a morphology of transition metal oxides with a length of a few millimeters would be useful, but it is very difficult to synthesize them with the synthesis techniques existing so far.

Several different techniques and routes are known for the synthesis of quasi one- dimensional structures (nanowires, microwires and ribbons) of transition metal dichalcogenides, consisting of crystallites of transition metal dichalcogenides, of quasi one-dimensional structures of metal oxides of transition metals, of nanotubes of transition metal dichalcogenides, and of nanostructures of transition metal dichalcogenides with a fullerene-like shape, however until now no process has been

described for the synthesis of macroscopic quantities of quasi one-dimensional structures of transition metal dichalcogenides, of metal oxides of transition metals, of nanotubes of transition metal dichalcogenides, and of nanostructures of transition metal dichalcogenides with a fullerene-like shape, using the chemical transformation of quasi one-dimensional materials, consisting of nanowires with the diameter of under one micrometer, described by the formula M ₆ CyH ₂ , 8.2<y+z<10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te); H is a halogen (I).

A technical problem is a simple synthesis of macroscopic quantities of long nanotubes of transition metal dichalcogenides, of nanostructures of transition metal dichalcogenides with a fullerene-like shape, of nanotubes of transition metal dichalcogenides, filled with nanostructures of transition metal dichalcogenides with a fullerene-like shape, and a process for the synthesis of macroscopic quantities of quasi one-dimensional structures of transition metal dichalcogenides, and of metal oxides of transition metals, using the chemical transformation of quasi one- dimensional materials, consisting of nanowires with a diameter of under one micrometer, described by the formula M ₆ CyH ₂ , 8.2<y+z<10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te); H is a halogen (I).

State of the Art

Several various techniques and synthesis routes are known for the synthesis of nanotubes of transition metal dichalcogenides, and of nanostructures of transition metal dichalcogenides with a fullerene-like shape. By means of irradiation of powdery particles of MoS ₂ layer crystals with electrons and by using laser evaporation, fullerene-like M0S ₂ nanoparticles can be obtained. These fullerene-like nanostructures have a closed spherical structure of sulphide layers - described in Jose-Yacaman, M.; Lorez, H.; Santiago, P.; Galvan, D. H.; Garzon, I. L.; Reyes, A. Appl. Phys. Lett. 1996, 69, 8, 1065; Parilla, P. A.; Dillon, A. C; Jones, K. M.; Rider, G.; Schulz, D. L.; Ginley, D. S.; Heben, M. J. Nature 1999, 397, 114. By irradiating MoS ₃ nanoparticles with short electric pulses, MoS ₃ nanoparticles are obtained,

- A - which are surrounded by some MoS ₂ layers with closed structures - described in Homyonfer, M.; Mastai, Y.; Hershfinkel, M.; Volterra, V.; Hutchison, J. L.; Tenne, R. J. Am. Chem. Soc. 1996, 118, 33, 7804. Inorganic fullerene-like nanostructures and MoS ₂ nanotubes can be also synthesized with chemical methods. The first syntheses of fullerene-like MS ₂ nanostructures (M = Mo, W) were based on sulphurization of an amorphous MO ₃ thin film (M = Mo, W) in reductive atmosphere at elevated temperatures (about 850 ⁰ C) - described in Tenne, R.; Margulis, L.; Genut, M.; Hodes, G. Nature 1992, 360, 444; Margulis, L.; Salitra, G.; Tenne, R.; Talianker, M. Nature 1993, 365, 113; Hershfinlkel, M.; Gheber, L. A.; Volterra, V.; Hutchison, J. L.; Margulis, L.; Tenne, R. J. Am. Chem. Soc. 1994, 116, 1914. The synthesis of fullerene-like MoS ₂ nanostructures, including MoS ₂ nanotubes, can be performed from molybdenum oxide powder instead on a precursor thin film. The synthesis, however, is suitable only for small quantities of the material at highly limited control of the size of nanoparticles formed - described in Feldman, Y.; Wasserman, E.; Srolovitz, D. J.; Tenne, R. Science 1995, 267, 222. Macroscopic quantities of fullerene-like WS ₂ nanostructures and WS ₂ nanotubes were synthesized from the powder of tungsten oxide nanoparticles - described in Feldman, Y.; Frey, G. L.; Homyonfer, M.; Lyakhovitskaya, V.; Margulis, L.; Cohen, H.; Hodes, G.; Hutchison, J. L.; Tenne, R. J. Am. Chem. Soc. 1996, 118, 5362; Rothschild, A.; Frey, G. L.; Homyonfer, M.; Tenne, R.; Rappaport, M. Mat. Res. Innovat. 1999, 3, 145. The synthesis is efficiently carried out only with more reactive oxides (e.g., WO ₃ ) in the temperature range from 700 ⁰ C to 850 ⁰ C, in which closed spherical structures of sulphide layers are obtained. The first sulphide layer inhibits the association of oxide nanoparticles into aggregates, and enables the growth of further concentric sulphide layers, typical of fullerene structures. The size and shape of fullerene-like particles is determined by initial oxide nanoparticles smaller than 300 nm, with larger particles layer crystals are obtained. Using special equipment at certain temperature conditions, a nearly pure phase of fullerene-like nanoparticles can be obtained. The method is not applicable to the synthesis of less reactive oxides, such as titanium and niobium oxide - described in Tenne, R.; Feldman, Y.; Zak, A.; Rosentsveig, R.; United States Patent Application 20040018306. Molybdenum and tungsten sulphide and selenide fullerene-like structures were prepared with the use of high energy

methods enabling high activation energies in very short time, such as irradiation with electrons - described in Stephan, O.; Bando, Y.; Loiseau, A.; Willaime, F.; Shramchenko, N.; Tamiya, T.; Sato, T. Appl. Phys. A - Mat. Sci. Proc. 67, 1 , 107- 111 , 1998, laser evaporation - described in Sen, R.; Govindaraj, A.; Suenaga, K.; Suzuki, S.; Kataura, H.; lijima, S.; Achiba, Y. Chem. Phys. Lett. 340, 3-4, 242-248, 2001 , microwave plasma - described in Vollath, D.; Szabo, D. V.; Act. Mat. 48 (4), 953-967, 2000, electric arc - described in Sano, N.; Wang, H. L.; Chowalla, M.; Alexandrou, I.; Amaratunga, G. A. J.; Naito, M.; Kanki, T.; Chem. Phys. Lett. 368, 3- 4, 331-337, 2003.

In a reaction between NbCI ₅ and H ₂ S at an elevated temperature, hollow NbS ₂ fullerenes are formed - described in Schuffenhauer, C; Popovitz-Biro, R.; Tenne, R. Jour. Mat. Chem. 12, 5, 1587-1591 , 2002. Fullerene-like MoS ₂ (MoSe ₂ ) structures were also efficiently synthesized in the reaction of a suitable metal halide with a sulphur reagent - described in Parilla, P. A.; Dillon, A. C; Jones, K. M.; Riker, G.; Schulz, D. L.; Ginley, D. S.; Heben, M. J. Nature 397, 6715, 114, 1999; TiS ₂ - described in Margolin, A.; Popovitz-Biro, R.; Albu-Yaron, A.; Moshkovich, A.; Rapoport, L.; Tenne, R. Curr. NanoScience 1 , 3, 253-262, 2005. ReS ₂ fullerene-like nanoparticles are formed by the sulphurization of ReO ₂ , which is formed by Reθ3 decomposition - described in Coleman, K. S.; Sloan, J.; Hanson, N. A.; Brown, G.; Clancy, G. P.; Terrones, M.; Terrones, H.; Green, M. L. H.; Jour. Amer. Chem. Soc. 124 (39), 11580-11581 , 2002.

The first inorganic nanotubes of transition metal chalcogenides were synthesized with the method of sulphurization of metal oxides - described in Tenne, R.; Rothschild, A.; Homyonfer, M.; United States Patent Base, US-P-6,217,843 (Appl. No. 308663). The material prepared in such a manner is composed of nanotubes of different diameter and wall thickness and contains many other admixtures. MoS ₂ and WS ₂ nanotubes can also be synthesized using a chemical transport reaction of MS ₂ powder (M = W, Mo) with iodine or bromine as transport reagents - described in Remskar, M.; Skraba, Z.; Cleton, F.; Sanjines, R.; Levy, F. Appl. Phys Lett. 1996, 69, 351 ; Remskar, M.; Skraba, Z.; Regula, M.; Ballif, C; Sanjines, P.; Levy, F. Adv.

Mater. 1998, 10, 246. The synthesis of nanotubes is also possible with the use of water solution of ammonium thiomolybdate, in which a porous aluminium membrane is soaked. This is followed by heating, which leads to the formation of M0S ₂ nanotubes, that are isolated by dissolving the membrane with KOH - described in Zelenski, C. M.; Dorhout, P. K. J. Am. Chem. Soc. 1998, 120, 734. By means of a modified transport reaction, which is catalyzed by C ₆ o, pure, ordered, monolayer tubular M0S ₂ structures are obtained - described in Remskar, M.; Mrzel, A.; Skraba, Z.; Jesih, A.; Ceh, M.; Demsar, J.; Sadelmann, P.; Levy, F.; Mihailovic, D. Science, 292, 479, 2001 ; Remskar, M.; Mrzel, A.; Skraba, Z.; Mihailovic, D. D.; Musevic, I.; International Application No.: PCT/SI2001 /000027, with the same diameter of under 1 nm, growing in the form of bundles. For a synthesis of this material a transport reaction is needed, which is relatively demanding and is unsuitable for a synthesis of large quantities of nanotubes. By means of a rapid thermolysis of ammonium molybdate molybdenum oxides were obtained having a spherical and rod-like form, which were transformed with H ₂ S to fullerene-like MoS ₂ nanostructures and MoS ₂ nanotubes - described in Therese, H. A.; Zink, N.; KoIb, U.; Tremel, W.; Sol. Stat. Sci. 8 (10): 1133-1137, 2006.

Until now it has not been reported on the synthesis and morphology of transition metal dichalcogenides, in which nanotubes of transition metal dichalcogenides are filled with nanostructures of transition metal dichalcogenides with a fullerene-like shape. Likewise, no report has been made on the process for the synthesis of macroscopic quantities of nanotubes of transition metal dichalcogenides, of nanostructures of transition metal dichalcogenides with a fullerene-like shape, and of nanotubes of transition metal dichalcogenides, filled with nanostructures of transition metal dichalcogenides with a fullerene-like shape, obtained by chemical transformation of quasi one-dimensional materials, described by the formula M ₆ CyH ₂ , 8.2<y+z≤10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te); H is a halogen (I).

MoS ₂ nanostructures are potentially interesting for the use in a variety of applications from nanoelectronics, photocatalysis, nanotribology, solar cells, in enzymes and in

obtaining hydrogen. The catalytic activity in hydrodesulphurization catalysis (HDS) is not only dependent on the type of edges in nanostructures and covering with sulphur, but also on the size of nanostructures. The best catalytic capabilities for HDS are expected in nanostructures having a weak interaction with a carrier (so- called type II) and having a size, where structural changes occur - described in Lauritsen, J. V.; Kibsgaard, J.; Helveg, S.; Topsoe, H.; Clausen, B. S.; Laegsgaard, E.; Besenbacher, F.; Nat. Nanotech. 58, 2, 2007.

Few different methods were used for the synthesis of nanowires and nanoribbons of transition metal dichalcogenides through precursor oxides. Precursor molecules of ammonium heptamolybdate tetrahydrate can be transformed into molybdenum trioxide having the morphology of nanoribbons and nanorods using different acids under hydrothermal conditions at 140 ⁰ C to 200 ⁰ C. With the use of H ₂ S/H ₂ at 600 ⁰ C the oxides can be transformed into M0S ₂ nanorods having the morphology of oxides preserved - described in Xiong Wen Lou and Hua Chun Zeng Chem. Mater. 2002, 14, 4781-4789. By the two-step synthesis - hydrothermal-gas reaction MOS ₂ -MOO ₂ nanostructural material was efficiently prepared, where the IvIoS ₂ crystallites on the MoO ₂ surface were mostly in the form of nanowires, ranging up to 30 nm. The measurements on nanostructures indicate an increased catalytic activity and selectivity - described in Camacho-Bragado, G. A.; Elechiguerra, J. L.; Olivas, A.; Fuentes, S.; Galvan, D.; Yacaman, M. J.; Jour. Cat. 234, 1 : 182-190, 2005. Polycrystalline MoS ₂ nano and microribbons were synthesized by the two-step electrochemical/chemical synthesis method, where the precursor MoO ₂ nanowires were first oriented in the electric field on the surface of pyrolytic graphite. These nanowires were transformed into MoS ₂ with H ₂ S at 900 ⁰ C. The ribbons formed had a length of up to 1 mm and were composed of MoS ₂ crystallites having a structure similar to conventional layer crystals - described in Li ₁ Q.; Newberg, J. T.; Walter, E. C; Hemminger, J. C; Penner, R. M.; Nano Lett. 4, 2, 277-281 , 2004. MoS ₂ nanorods having a diameter of about 20 nm are formed by 24 hour-hydrothermal method from water solution of (NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O, C ₂ H ₄ NS and Na ₂ S ₂ O ₄ at 190 ⁰ C, whereby the product formed was thereafter heated still in nitrogen - described in Ota, J. R.; Srivastava, S. K.; Jour. NanoSci. Nanotech. 6, 1 , 168-174, 2006.

MOO3 nanowires with orthorhombic structure and a diameter of about 10 nm were synthesized by electrodeposition. These nanowires show higher sensitivity to ammonia than the conventional sol-gel sensors - described in Gouma, P.; Bishop, A.; Yer, K. K. Rare Met. Mat. Engin. 35, 295-298, 3, 2006. The oriented nanowires of MoO ₃ with similar length and diameters were prepared in two-step synthesis - by the temperature evaporation and oxidation - described in Zhou, J.; Deng, S. Z.; Xu, N. S.; Chen, J.; She, J. C; Appl. Phys. Lett. 83, 13, 2653-2655, 29, 2003. Macroscopic quantities of MoO ₃ nanostructures with various morphologies, such as nanoflowers, nanoribbons and nanoleaves were synthesized by a chemical route with the use of H2O2 and molybdenum - described in Li, G. C; Jing, L.; Pang, S. P.; Peng, H. R.; Zhang, Z. K. Jour. Phys. Chem. B 110, 48, 24472-24475, 7, 2006. Anisotropic crystalline nanostructures of alfa MoO ₃ were synthesized by the decomposition and condensation of peroxymolybdenum acid under hydrothermal conditions. Nanostructures formed have a width of 200 to 300 nm, a thickness of 60 to 90 nm and a length of up to 10 micrometers - described in Fang, L.; Shu, Y. Y.; Wang, A. Q.; Zhang, T. Jour. Phys. Chem. C 111 , 6, 2401-2408, 2007. Molybdenum oxide crystals were synthesized by acid decomposition of sodium molybdate under hydrothermal conditions. Under the synthesis conditions a well oriented phase can be obtained, composed of crystallites oriented along the direction, whereat the phase is even up to a few centimeters long. This material is also useful as a starting material for molybdenum chalcogenides - described in Camacho-Bragado, G. A.; Jose-Yacaman, M. Appl. Phys. A - Mat. Sci. Proc. 82, 1 , 19-22, 2006.

Task and Aim of the Invention

The task and aim of the invention is a process for the synthesis of macroscopic quantities of nanotubes of transition metal dichalcogenides, of nanostructures of transition metal dichalcogenides with a fullerene-like shape, of nanotubes of transition metal dichalcogenides, filled with nanostructures of transition metal dichalcogenides with a fullerene-like shape, of quasi one-dimensional structures of

transition metal dichalcogenides, consisting of interlinked fine crystallites of transition metal dichalcogenides, and the synthesis of quasi one-dimensional structures of metal oxides of transition metals.

According to the invention, the task is solved by a process for the synthesis of macroscopic quantities of nanotubes of transition metal dichalcogenides, of nanostructures of transition metal dichalcogenides with a fullerene-like shape, of nanotubes of transition metal dichalcogenides, filled with nanostructures of transition metal dichalcogenides, with a fullerene-like shape, of quasi one-dimensional structures of transition metal dichalcogenides, consisting of fine crystallites of transition metal dichalcogenides, and of quasi one-dimensional structures of transition metal oxides, according to independent patent claims.

Description of the Invention

The invention will be described by examples of application I and II.

Example of application I:

Individual figures of the example of application I present:

Fig. 1-1 : A schematic presentation of the experiment performed in a zone oven.

Fig. I-2: Figures (2a, 2b) of MoS ₂ material formed by sulphurization of Mo ₆ S ₂ Is nanowires, taken by the scanning electron microscope SEM JEOL JXA-840A.

Fig. I-3: Transmission electron microscopy (TEM) of the MoS ₂ material formed, taken by the field emission transmission electron microscope Jeol 2010 F (Figures 3a, 3b,

3c).

Fig. I-4: High resolution transmission electron microscopy (HRTEM) of fullerene-like

MoS ₂ nanostructures, taken by the field emission transmission electron microscope

Jeol 2010 F.

Fig. 1-5: Transmission electron diffraction (TED) on a M0S ₂ fullerene inside a MoS ₂ nanotube, taken by the field emission transmission electron microscope Jeol 2010 F.

The above described technical problem can be solved by chemical transformation of quasi one-dimensional materials, described by the formula M ₆ CyH ₂ , 8.2<y+z<10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te); H is a halogen (I). The chemical transformation (sulphurization) was carried out in a quartz tube with gas containing 98 % of argon as a carrier gas, 1 % of H ₂ S and 1 % of H ₂ . The reaction occurred at an elevated temperature in one-zone oven according to Fig. 1-1. This transformation of quasi one-dimensional ternary materials of transition metals leads to the replacement of the iodine with a chalcogen (e.g. sulphur) and the transformation into nanotubes of transition metal dichalcogenides, into nanostructures of transition metal dichalcogenides with a fullerene-like shape, and into nanotubes of transition metal dichalcogenides, filled with nanostructures of transition metal dichalcogenides with a fullerene-like shape.

The example of application of the synthesis of nanotubes of transition metal dichalcogenides, of fullerene-like nanostructures of transition metal dichalcogenides and of nanotubes of transition metal dichalcogenides, filled with fullerene-like nanostructures of transition metal dichalcogenides, is carried out by chemical transformation of quasi one-dimensional materials, described by the formula MβCyHz, 8.2<y+z<10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te); H is a halogen (I).

Experiment

Into a quartz boat, 50 mg of Mo ₆ S ₂ Is nanowires were introduced, which had been synthesized directly from the elements, as described in Patent Application EP 1 541 528. The boat with MOeS ₂ Is nanowires was placed into a quartz tube with a diameter of 34 mm, a wall thickness of 2 mm and a length of 1000 mm, closed at one end, and fitted with rough surface at the other end, enabling the closure of the tube after

- l i the introduction of the boat with the material and a simultaneous inlet of the gas into the quartz tube. The quartz tube also had a quartz outlet for the outlet of gases as shown in Figure 1-1.

The closed quartz tube was first purged with argon for 15 minutes and then it was continued with blowing with gas 1 composed of 98 % of argon, 1 % of H ₂ S and 1 % of H ₂ for 10 minutes. The gas flow-rate was 40 cm ³ of gas per minute. The quartz tube was carefully introduced into the heated one-zone oven. The temperature of the site where the boat was placed was 837 ⁰ C, as measured by a thermocouple. After two hours of blowing with gas 1 at this temperature, the quartz tube was taken out of the zone-oven and left at room temperature for half an hour to cool down. During the whole process, blowing with gas 1 was continued. After half an hour, when the quartz tube was cooled down, gas 1 was turned off and the boat with the material formed was taken out of the quartz tube. The weight of the material formed was 30 mg.

Structural and Chemical Analyses

The material formed was examined with several different techniques:

1. Scanning Electron Microscopy was performed with SEM JEOL JXA-840A. Scanning electron microscopy showed that after the sulphurization at a temperature of 837 ⁰ C the material formed preserved the form of the starting material, i.e. fibres with a length of even up to several millimeters.

2. High Resolution Transmission Electron Microscopy (HRTEM) and Diffraction (TED), taken by the 200 keV field emission transmission electron microscope Jeol 2010 F.

Transmission electron microscopy indicated that the material was mostly composed of MoS ₂ nanotubes, filled with M0S ₂ fullerene structures (Figures l-3a, l-3b). The

tubes are partly or completely filled with fullerene structures, consisting either of aggregates of individual fullerenes (A) or of individual flattened spheroids (B). Individual hollow nanotubes (Figure l-3b) are also present. Nanotubes are closed at the ends, walls have a variable thickness, mostly enlarged at the ends (Figure l-3b). The fullerenes show a hollow centre (Figure 1-4) and a high degree of regularity of concentric spheres. MoS ₂ fullerenes captured in the tubes have very different diameters, from a few hundred nanometers (C) to several tens nanometers (D) - (Figure l-3c). The electron diffraction on an individual fullerene (Figure 1-5) shows the presence of M0S2 phase only, mostly with hexagonal stacking (JCPDS-lnternational Centre for Diffraction Data, No. 06-0097), partly also with the rhombohedral stacking (JCPDS-lnternational Centre for Diffraction Data, No. 77-0341). Strong reflexes forming a deformed hexagonal grid, belong to the tube-envelope, and the reflexes forming the rings belong to the diffraction on the M0S ₂ fullerene.

3. X-ray Powder Diffraction

X-ray powder patterns of specimens in glass capillary tubes with an inner diameter of 0.3 mm were taken by the Debye-Scherrer method in a camera with a diameter of 57.3 mm and CuK ₀ X-ray (λ = 1.5418 A). Positions of diffraction lines on the film were measured with the accuracy of 0.005 mm, the intensity of the lines was estimated visually.

The interplanar distances measured correspond to the interplanar distances of hexagonal and rhombohedral MoS ₂ , with the exception of five weak lines with interplanar distances of 8.762 A, 7.476 A, 6.837 A, 3.244 A and 1.705 A. The results of X-ray powder diffraction of sulphurization products confirm the composition of MoS ₂ with minor quantities of unidentified by-products.

Table 1. A comparison of interplanar distances and intensity of X-ray diffraction lines of the sulphurization product and of M0S ₂ layer crystals

Sulphurization Product MoS ₂ , 60-097 MoS ₂ , 77-0341

d [A] Intensity d [A] Intensity d [A] Intensity

8.762 1

7.476 2

6.837 2

6.166 100 6.15 100 6.1366 100

3.244 1

2.987 2 3.075 4 3.0683 1

2.742 1 2.737 16 2.7119 25

2.688 5 2.674 10 2.6277 23

2.489 5 2.501 8

2.297 1 2.277 45

2.221 5 2.1990 33

2.045 5 2.049 14 2.0455 5

1.902 2 1.8980 18

1.820 1 1.83 25

1.748 2 1.7626 10

1.705 2

1.645 2 1.641 4

1.580 5 1.581 12 1.5830 14

1.533 3 1.538 12 1.5328 10

1.362 1 1.3688 2 1.3671 2

1.311 1 1.3401 4 1.3138 4

1.289 1 1.2983 6 1.2847 4

1.250 1 1.2513 4 1.2519 5

Temporal Stability and Synthesis Reproducibility

The material formed, composed of MoS ₂ nanotubes, of fullerene-like MoS ₂ nanostructures, and of M0S ₂ nanotubes, filled with fullerene-like MoS ₂ nanostructures, is stable in the air under room conditions. The stability of the compound and synthesis reproducibility were controlled by transmission electron microscopy (TEM).

The process for the synthesis of nanotubes of transition metal dichalcogenides, of fullerene-like nanostructures of transition metal dichalcogenides, and of nanotubes of transition metal dichalcogenides, filled with fullerene-like nanostructures of transition metal dichalcogenides, according to the present invention, is therefore characterized in that the synthesis occurs by means of chemical transformation of quasi one-dimensional materials, described by the formula M ₆ CyH ₂ , 8.2<y+z≤10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te), H is a halogen (I). The chemical transformation of quasi one-dimensional materials, described by the formula M ₆ CyH ₂ , 8.2<y+z≤10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te), H is a halogen (I), is carried out in the presence of at least one reactive reagent, containing a chalcogen. The chemical transformation of quasi one-dimensional materials, described by the formula M ₆ CyH ₂ , 8.2<y+z<10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se ₁ Te), H is a halogen (I), is carried out under conditions, in which the reactive reagent, containing a chalcogen, is present in vapour phase. The morphology of the material of transition metal dichalcogenides, obtained by the process according to this invention, is characterized in that the fullerene-like nanostructures of transition metal dichalcogenides are inside nanotubes of transition metal dichalcogenides.

Example of application II:

Individual figures of the example of application Il present:

Fig. 11-1 : A schematic presentation of the experiment of the transformation of quasi one-dimensional materials, consisting of nanowires with a diameter of under one micrometer, described by the formula M ₆ C ₃ H ₆ , into quasi one-dimensional molybdenum oxides, performed by heating in the air in a zone oven. Fig. II-2: A schematic presentation of the experiment of sulphurization of quasi one- dimensional structures of molybdenum oxides, performed in a zone oven with the gas 1 composed of argon/ H2S/ H ₂ .

Fig. II-3: The image of quasi one-dimensional structures of transition metal oxides formed, taken by the field emission scanning electron microscope FE-SEM, Supra 35 VP, Carl Zeiss.

Fig. II-4: The image of quasi one-dimensional structures of transition metal oxides formed, taken by the field emission transmission electron microscope Jeol 2010 F. Fig. II-5: The electron microscopy image of one nanowire of transition metal oxides, taken by the field emission transmission electron microscope Jeol 2010 F, shows the polycrystalline structure and fine crystallites, growing perpendicularly to the direction of a fiber.

Fig. II-6: Electron diffraction belonging to Figure 5, demonstrating, that the oxide phase formed is MO ₅ O ₁₄ . The image is taken in such a manner, that the [001] axis in the crystal is parallel to the electron beam.

Fig. II-7: The electron microscopy image, taken by the field emission transmission electron microscope Jeol 2010 F, showing one nanowire of transition metal oxides after sulphurization. Polycrystalline structure is visible.

Fig.ll-8: Electron diffraction belonging to Figure 7, demonstrating, that the material is completely transformed into M0S ₂ . From the variable intensity of individual rings it is evident, that the crystallites are not completely randomly oriented, however orientation order is partly present among them.

The above described technical problem is according to the invention solved by chemical transformation of quasi one-dimensional materials, consisting of nanowires with a diameter of under one micrometer, described by the formula M ₆ C _y H _z , 8.2<y+z<10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te), H is a halogen (I). The chemical transformation of quasi one-dimensional

materials, consisting of nanowires with a diameter of under one micrometer, described by the formula M ₆ C _y H _z , 8.2<y+z<10, where M is a transition metal (Mo ₁ W, Ta, Nb), C is a chalcogen (S, Se, Te), H is a halogen (I), is carried out in two steps, actually first in the step of heating in the presence of oxygen, whereby transformation of nanowires into quasi one-dimensional metal oxides of transition metals takes place, followed by the sulphurization process. The starting material in the form of quasi one-dimensional materials, consisting of nanowires with a diameter of under one micrometer, described by the formula MβCyHz, 8.2<y+z≤10, is first heated in the air, or in the presence of oxygen, at temperatures above 200 ⁰ C and below 2000 ⁰ C, as it is shown in Figure 11-1. One-dimensional structures of metal oxides of transition metals are formed thereby.

Chemical transformation, sulphurization of metal oxides of transition metals, formed from quasi one-dimensional materials, consisting of nanowires with a diameter of under one micrometer, described by the formula MeCyHz, 8.2<y+z<10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te); H is a halogen (I), is carried out under conditions, in which the reactive reagent, containing a chalcogen, exists in vapour phase. The sulphurization of transition metal oxides occurs in a quartz tube with gas 1 , containing 98 volume percent of argon as a carrier gas, 1 volume percent of H ₂ S and 1 volume percent of H ₂ . The reaction occurs in one-zone oven as it is schematically shown in Figure II-2. The reactive reagent for the sulphurization H ₂ S is thereby in vapour phase.

This transformation of quasi one-dimensional ternary materials, consisting of nanowires with a diameter of under one micrometer, according to the two-step process described, leads to the replacement of the iodine with a chalcogen (e.g. sulphur) and to the transformation into quasi one-dimensional structures of transition metal dichalcogenides, consisting of fine crystallites of transition metal dichalcogenides.

The process for the synthesis of quasi one-dimensional structures of transition metal dichalcogenides, according to this invention, is therefore characterized in that

the synthesis occurs by means of chemical transformation of quasi one-dimensional materials, consisting of nanowires with a diameter of under one micrometer, described by the formula M ₆ C _y H _z , 8.2<y+z<10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te), H is a halogen (I). The chemical transformation of metal oxides of transition metals formed of quasi one-dimensional materials, consisting of nanowires with a diameter of under one micrometer, described by the formula M ₆ C _y H _Zl 8.2<y+z<10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te), H is a halogen (I), is carried out under conditions, in which the reactive reagent, containing a chalcogen, is present in vapour phase. Quasi one-dimensional material consisting of nanowires is, according to this invention, first heated in the air or in the presence of oxygen, at temperatures higher than 200 ⁰ C in such a manner, that it is transformed into an oxide, which preserves, however, the basic form of nanowires. This is followed by sulphurization and nanowires of transition metal dichalcogenides are formed, which consist, however, of fine crystallites. So this concerns a synthetic process for preparing oxides from basic nanowires and a synthetic process for preparing nanowires of transition metal dichalcogenides, consisting of crystallites of transition metals, from basic nanowires with a diameter of under one micrometer, described by the formula M ₆ CyH ₂ , 8.2<y+z≤10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te); H is a halogen (I), through oxides. The morphology of the material of transition metal dichalcogenides, obtained by the process according to the invention, is characterized in that they have the configuration of quasi one- dimensional transition metal dichalcogenides (nanowires, microwires and ribbons of transition metal dichalcogenides), consisting of fine crystallites of transition metal dichalcogenides.

Experiment

The example of application describes the synthesis of quasi one-dimensional structure of transition metal dichalcogenides by the chemical transformation of quasi one-dimensional materials, consisting of nanowires with a diameter of under one

micrometer, described by the formula M ₆ C _y H _Zl 8.2<y+z<10, where M is a transition metal (Mo, W, Ta, Nb), C is a chalcogen (S, Se, Te), H is a halogen (I).

Into a quartz boat, 50 mg of Mo ₆ S ₂ Is nanowires were introduced, which had been synthesized directly from the elements, as described in Patent Application EP 1 541 528. The boat with a material composed of bundles of Mo ₆ S ₂ Is nanowires was placed into a quartz tube with a length of 1000 mm and a diameter of 32 mm in an one-zone oven, heated to 380 ⁰ C, and the material was heated in the air for two hours. A trap, cooled with water, was placed at one side of the quartz tube. The trap served for collecting the iodine released and simultaneously enabled the access of the air to the material in the boat. The schematic course of heating is shown in Figure 11-1. The weight of the material formed, consisting of quasi one-dimensional structures of metal oxides of transition metals (nanowires, microwires and ribbons), was 27 mg.

The boat with quasi one-dimensional transition metal oxides formed was placed into a quartz tube with a diameter of 34 mm, a wall thickness of 2 mm and a length of 1000 mm, closed at one end, and fitted with rough surface at the other end, enabling the closure of the tube after the introduction of the boat with the material and a simultaneous inlet of the gas into the quartz tube. The quartz tube also had a quartz outlet for the outlet of gases as shown in Figure II-2.

The closed quartz tube was first purged with argon gas for 20 minutes and then it was continued with blowing with gas 1 composed of 98 % of argon, 1 % of H ₂ S and 1 % of H ₂ for 15 minutes. The gas 1 flow-rate was 30 cm ³ per minute. The quartz tube was carefully introduced into the heated one-zone oven. The temperature of the site where the boat was placed was 860 ⁰ C, as measured by a thermocouple. After two hours of blowing with gas 1 at this temperature, the quartz tube was taken out of the zone-oven and left at room temperature for half an hour to cool down. During the whole process, blowing with gas 1 was continued. After half an hour, when the quartz tube was cooled to the temperature below 50 ⁰ C, gas 1 was turned off and

the boat with the material formed was taken out of the quartz tube. The weight of the material formed was 30 mg.

The phases formed by oxidation and sulphurization were examined with scanning electron microscopy (SEM) - Figure 11-3, transmission electron microscopy (TEM) - Figures 11-4,5,7 and electron diffraction (TED) - Figures 11-6,8.