WO1997044278A1 - Synthese en masse de structures de chalcogenures de metal de type fullerenes inorganiques - Google Patents

Synthese en masse de structures de chalcogenures de metal de type fullerenes inorganiques Download PDF

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WO1997044278A1
WO1997044278A1 PCT/IL1997/000165 IL9700165W WO9744278A1 WO 1997044278 A1 WO1997044278 A1 WO 1997044278A1 IL 9700165 W IL9700165 W IL 9700165W WO 9744278 A1 WO9744278 A1 WO 9744278A1
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metal
gas
nanoparticles
chalcogen
particles
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PCT/IL1997/000165
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Reshef Tenne
Gary Hodes
Yishay Feldman
Moshe Homyonfer
Lev Margulis
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Yeda Research And Development Co. Ltd.
MARGULIS, Helena
MARGULIS, Michael
MARGULIS, Maxim
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Publication of WO1997044278A1 publication Critical patent/WO1997044278A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/20—Methods for preparing sulfides or polysulfides, in general
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B19/00—Selenium; Tellurium; Compounds thereof
    • C01B19/007—Tellurides or selenides of metals
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G1/00—Methods of preparing compounds of metals not covered by subclasses C01B, C01C, C01D, or C01F, in general
    • C01G1/12—Sulfides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G41/00—Compounds of tungsten
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
    • C01P2002/84—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by UV- or VIS- data
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
    • C01P2004/13—Nanotubes
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/30—Particle morphology extending in three dimensions
    • C01P2004/32—Spheres
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer

Definitions

  • the present invention relates in general to a method and apparatus for preparing inorganic fullerene-like structures of metal, e.g. transition metal, chalcogenides, and more particularly, to a solid-gas method and reactor for high yield preparation of macroscopic quantities of such inorganic fullerene-like particles of desired size and shape.
  • metal e.g. transition metal, chalcogenides
  • Graphite is the most stable form of carbon under ambient conditions. Nevertheless, graphite nanoclusters have been shown to be unstable against folding and close into fullerenes (Kroto et al..l985), nested fullerenes (Iijima, 1980) and nanotubes (Iijima, 1991 ). It is believed (Robertson et al., 1992) that the main stimulus to form carbon fullerenes (CF) emanates from the large energy associated with the dangling covalent bonds of the peripheral carbon atoms in graphite nanoclusters.
  • CF carbon fullerenes
  • the innermost layer serves as a template for the growth of the top layers, which usually grow outwards (Ugarte, 1992), possibly in an accretion (snail-like) growth mode (Kroto, 1988).
  • inorganic fullerenes Particles of inorganic structures having a layered configuration (a single layer or nested layers) arc known as inorganic fullerenes (IF).
  • inorganic layered structures such as but not limited to spheres, whiskers, nanotubes, polyhedral and others, will interchangeably be referred to as “inorganic fullerene- like" or “IF" materials, throughout the specification.
  • Nanoclusters of IF metal chalcogenide materials such as WS2 and M0S2, were recently described (Tenne et al., 1992; Margulis et al., 1993; Hershfinkel et al., 1994; EP 0 580 019).
  • WS2 and M0S2 Metal chalcogenide materials
  • the IF particles have several interesting and useful applications, and it would be very advantageous to have a method and apparatus for high yield preparation of macroscopic quantities of IF particles of metal, e.g. transition metal, chalcogenides having a desired size and shape.
  • metal e.g. transition metal, chalcogenides having a desired size and shape.
  • inorganic fullerene-like refers to inorganic metal chalcogenide structures having one layer or nested layers which form what is known in the art as a closed cage (Tenne et al., 1992; Margulis el al., 1993) which may encage a void (i.e., be hollowed) or a core or may form a stuffed nested layer structure, i.e. a structure containing a material other than the metal material precursor encaged within nested layers of the metal chalcogenide.
  • the term refers to structures such as what is known in the art as single and double layer inorganic fullerenes (Srolovitz et al., 1995), nested layers inorganic fullerenes (Tenne et al., 1992), stuffed inorganic fullerenes (Margulis et al., 1993, single layer nanotubes (Bethune et al., 1993; Iijima and Ichiashi, 1993), nested nanotubes (Iijima, 1991 ) stuffed nanotubes (Ajayan and S. Iijima, 1993), and inorganic supperlattice structures, i.e. IF particles having layers of two or more different chalcogenides of the metal, e.g. WS 2 and Wse 2 .
  • nanoparticles of metal chalcogenides including one or more layers of desired sizes and shapes, e.g., spheres, sphere-like, nanotubes and polyhedral shapes, may be manufactured.
  • the metals that are suitable for this method are metals that form layered metal chalcogenide products in a solid-gas reaction such as In, Ga, Sn and a transition metal selected from Mo, W, V, Zr, Hf, Pt, Re, Nb, Ta, Ti, Cr and Ru.
  • the present invention thus relates in one aspect to a solid-gas method for the bulk synthesis of inorganic fullerene-like (IF) structures of metal chalcogenides from a solid non-volatile metal material precursor, said IF structures having a desired size and shape being predetermined by the size and shape of the said metal material precursor, wherein said metal is selected from In, Ga, Sn and a transition metal selected from Mo, W, V, Zr, Hf, Pt.
  • IF inorganic fullerene-like
  • said method comprising the steps of: (a) dispersing in a reactor solid nanoparticles of at least one non-volatile metal material having the preselected size and shape, said dispersion being such that, upon heating, agglomeration and fusion of said solid nanoparticles into larger particles are substantially avoided, while the top surface of said solid particles is substantially completely exposed to a gaseous atmosphere;
  • Heating in step (a) is carried out a temperature within the range of 650-850 °C for a time shorter than 60 seconds to produce IF structures with one layer encaging said metal material, and for 1-20 min to produce IF structures with 2-5 layers encaging said metal material.
  • the method of the present invention comprises further heating at the same temperature the IF particles of step (a) in said reducing gaseous atmosphere containing said at least one chalcogen material gas, for a time sufficient to allow said metal material and said chalcogen material gas to further react through a slow diffusion controlled reaction, wherein the metal material core is progressively converted into a metal chalcogenide nanoparticle with an empty core, and nested IF structures are thus obtained and recovered.
  • the reaction mixture is further heated at 650- 850 °C for 20-120 min to produce multilayered IF structures.
  • the heating time is shorter for the production of metal sulfides and longer for the corresponding metal selenidcs.
  • the metal material precursor should be heated with H 2 S for less than 60 min, while for the production of larger particles (>50 nm), the heating time should be 90- 120 min.
  • the metal is a transition metal, selected from Mo,W, V, Zr, Hf, Pt, Re, Nb, Ta, Ti, Cr and Ru.
  • the metal, preferably transition metal, material used as precursor in the method of the invention is at least one non-volatile metal material selected from the group consisting of a metal, a compound containing a metal, a mixture of metals, a mixture of compounds containing a metal and a mixture of a metal and a compound containing a metal.
  • non-volatile metal material selected from the group consisting of a metal, a compound containing a metal, a mixture of metals, a mixture of compounds containing a metal and a mixture of a metal and a compound containing a metal.
  • Examples of such metal materials are non-volatile metals, mixtures of metals, alloys e.g. W 0 2 Mo 0 8 , metal oxides and metal carbides.
  • the metal material is a metal oxide selected from a tungsten oxide selected from W0 3 , W 20 O 58 , and W, 8 O 49 ; Zr0 2 , Hf0 2 , PtO 2 , ln 2 0 3 , Ga 2 0 3 , Nb 2 O s , Ta 2 0 3 , ReO 3 , TiO 2 , SnO 2 , and Ru0 2 .
  • the chalcogen according to the invention is S, Se or Te
  • the chalcogen material as defined herein is selected from the group consisting of a chalcogen, a compound containing a chalcogen, a mixture of chalcogens, a mixture of compounds containing a chalcogen and a mixture of a chalcogen and a compound containing a chalcogen.
  • the chalcogen material is preferably a chalcogen compound containing hydrogen, more preferably H2S, H2Se, and/or H2Te.
  • the size of the IF particles produced by the method of the invention is selected according to the potential application of the IF structures and is in the nanometer range, preferably ⁇ 300 nm, more preferably ⁇ 150 nm, and most preferably ⁇ 30 nm.
  • the shape of the IF nanoparticles produced by the method of the invention is also selected according to the potential application of the IF structures and is determined by the shape of the metal material precursor.
  • sphere-like particles and whiskers of the metal material precursor will produce sphere-like particles and nanotubes, respectively, of the metal chalcogenides.
  • the IF structures produced by the method of the invention include, but are not limited to, single layer inorganic fullerenes, nested layers inorganic fullerenes, stuffed inorganic fullerenes, single layer nanotubes, nested nanotubes, stuffed nanotubes, inorganic supperlattice structures, and structures with negative curvature (Schwartzites).
  • the metal material is W0 3 and the chalcogen material is H 2 S gas.
  • the solid W0 3 nanoparticles are first dispersed on the floor of the reactor to avoid agglomeration and fusion of the heated nanoparticles, the dispersed nanoparticles of WO 3 are reacted at a temperature in the range of 650-850°C with a mixture of H 2 S gas with a forming gas, typically 5% H 2 /95% N 2 , whereby the W0 3 is reduced to WO 3-x and gradually converted to WS 2 , and the reaction products are collected on a substrate and progressively converted into the desired nested IF-WS 2 polyhedra.
  • the invention relates to an apparatus for preparing macroscopic quantities of inorganic fullerene-like nanoparticles of metal chalcogenides having a desired size and shape according to the method of the invention, the apparatus comprising:
  • heating means for heating said small tubes said preselected quantity of the metal material being selected such that said solid nanoparticles are dispersed to a degree such that agglomeration and fusion of said solid nanoparticles into larger particles during said heating are substantially avoided, while the surface of said nanoparticles is substantially completely exposed to said chalcogen material gas.
  • Said apparatus may further comprise: (d) first flow control means for controlling the flow of forming gas; and (e) second flow control means for controlling the flow of chalcogen material gas.
  • the present invention relates to an apparatus for preparing macroscopic quantities of inorganic fullerene-like nanoparticles of metal chalcogenides having a desired size and shape according to the method of the invention, the apparatus comprising:
  • a chamber having a lower end and an upper end, said chamber being for accommodating solid nanoparticles of at least one non-volatile metal material having a preselected size and shape;
  • a gas penetrateable cover covering said lower end of said chamber, said gas penetrateable cover being for providing said chamber with an inward flow of carrier gas for floating said solid particles in said chamber;
  • heating means for heating said chamber said flow of gas being selected such that said solid nanoparticles ot the metal material are dispersed to a degree such that agglomeration and fusion of said solid particles into larger particles during said heating are substantially avoided, while the surface of said solid particles.
  • transition metal chalcogenides e.g., WS2, WSe2, M0S2, MoSe2, SnS2, SnSe2, RuS2, GaS, GaSe, InS, InSe, etc.
  • electrochemical and photovoltaic solar cells production e.g., WS2, WSe2, M0S2, MoSe2, SnS2, SnSe2, RuS2, GaS, GaSe, InS, InSe, etc.
  • electrochemical and photovoltaic solar cells production Abruna and Bard 1982; Djemal et al., 1981
  • photocatalysis Rosenberg et al., 1992; Dagan and Tomkiewicz, 1993
  • solid lubrication such as in high or low temperature environments or under ultra high vacuum where liquid lubricants are not suitable (Dimigen et al., 1979), and in ferro fluid lubrication, sealing and levitation applications.
  • IF materials of the above mentioned compounds are believed to outperform the bulk materials in the aforementioned applications. Since the outer surface of the IF material exposes only the basal plane of the compound, this material lends itself to solid lubrication applications. Indeed, IF nanoparticles do not stick to each other or the substrate and exhibit poor surface adhesion. Their approximate sphero-symmetric shapes imply easy sliding and rolling of the nanoparticles and consequently very- small shear forces are required to move them on the substrate surface. The absence of edges in IF semiconductors is believed to alleviate the problem of surface recombination which hinders the application efficiency of the bulk photocatalysts.
  • IF particles may be used in the field of nanoelectronics and magnetic information storage, since such particles exhibit magnetic phase transition. It will be appreciated by one ordinarily skilled in the art that for many such applications the ability to preselect the size and shape of the IF particles is of great importance. This is the case when solid lubrication is of concern since controlling the size and shape determines the surface energy of the particles which is of great importance concerning lubrication capabilities.
  • Fig. 1 is a schematic representation of the growth model of the inorganic fullerene-like phase of IF-WS2 nested polyhedra from oxide nanoparticles according to the method of the present invention.
  • Figs. 2A-2C are transmission electron microscopy (TEM) micrographs showing the gradual transformation of tungsten oxide nanoparticles into IF-WS2 nested polyhedra, according to the method of the present invention.
  • TEM transmission electron microscopy
  • Figs. 3A-3D are TEM micrographs showing the transformation of tungsten oxide nanoparticles into IF-WS2 according to the method of the present invention, wherein Fig. 3 A shows a typical assortment of tungsten oxide particles with ⁇ 10 nm diameter which are transformed into IF-WS2 particles of a similar size and shape, shown in Fig. 3B, whereas Figs. 3C and 3D show a similar transformation for tungsten oxide particles with a diameter in the range of 50-150 nm.
  • Fig. 4 shows the transformation of WO3 nanoparticles into IF-WS2 followed by X-ray powder diffraction, wherein curve A presents difraction of the WO3 precursor powder, curve B presents the same powder after two minutes of HS2 annealing, curve C presents the powder after eight minutes annealing, curve D presents the powder after fifteen minutes annealing and curve E presents the powder after 120 minutes annealing, wherein the annealing conditions are: 850 °C, rates of gas flow: forming gas, 130 cc/min; H2S gas -- 2 cc/min.
  • Fig. 5 depicts optical abso ⁇ tion measurements of composite IF-WS2/WO3.
  • the annealing conditions are as in Fig. 4 above.
  • Fig. 6 is a cross section view of an apparatus used for high yield synthesis of macroscopic quantities of transition metal chalcogenides according to the present invention.
  • Fig. 7 is a cross section view of an apparatus used for high yield synthesis of macroscopic quantities of IF-WS2 particles in a solid-gas continuos process according to the present invention.
  • the present invention is directed to a method and apparatus for high yield preparation of macroscopic quantities of inorganic fullerene-like (IF) nanoparticles, i.e., particles in the nanometer range, of In, Ga, Sn and transition metal chalcogenides, wherein the transition metal is Mo, W, V, Zr, Hf, Pt, Re, Nb, Ta, Ti, Cr or Ru, which IF structures can be used for production of electrochemical and photovoltaic solar cells, solid lubrication, photocatalysis, production of battery cathodes, catalysis and numerous other applications.
  • IF inorganic fullerene-like
  • FIG. 1 A schematic representation of the growth model of WS2 particles according to the method of the invention is depicted in Figure 1.
  • the top surface of the sublimed oxide nanoparticle reacts with H2S gas and a completely closed monomolecular WS2 layer or two are formed.
  • the inert surface- sulfide layer prohibits fusion of nanoparticles into macroscopic entities, which would lead to the formation of e.g., a 2H-WS2 phase.
  • Fast hydrogen diffusion into the nanoparticle leads to a complete reduction of the oxide core into W, 8 O 49 within a minute or two ( Kung, 1989).
  • the oxide core is progressively converted into WS2 through a slow diffusion-controlled reaction, which ends after ca. 60 minutes. Consequently, the size and shape of the IF particle thus formed is determined by the size and shape of the incipient oxide nanoparticle.
  • metal chalcogenide IF particles is very much different from other growth mechanisms attributed for other types of particles growing outwardly possibly in an accretion (snail-like) growth mode (Iijima and Ichiashi, 1993; Ugarte, 1992; Kroto, 1988), as being an inwards type growth mechanism; and therefore the size and shape of the products (i.e., IF particles) may be determined by selecting the size and shape of the reactants.
  • the above described growth mechanism differs also from the growth mechanism of platelets with e.g., two repeat units and hexagonal packing (211), or three repeat units with rhombohedral packing (3R), etc., (Wilson and Yoffe, 1968).
  • the method of the present invention provides bulk synthesis, i.e. high yield preparation of macroscopic quantities of inorganic fullerene-like (IF) particles of metal chalcogenides having a preselected size and shape, and includes (a) dispersing solid particles (e.g., a powder) of at least one non- volatile metal material precursor having the preselected size and shape; and (b) heating the solid particles of the metal material in a gaseous reducing atmosphere containing at least one chalcogen material for a time and a temperature sufficient to allow the metal material(s) and the chalcogen material(s) to react and form at least one layer (typically one or two layers at this early stage) of metal chalcogenide, which is encaging (i.e., engulfing) the surface of the solid precursor particles to form the IF particles.
  • a most important feature of the method of the present invention is that the dispersion of the solid particles is such that agglomeration and fusion of the solid particles into larger particles upon heating are substantially avoided (i.e., preferably at least 90%, more preferably 95%, most preferably 99% or more percent of the solid particles are in no contact with neighboring particles), so that the surface of the solid particles is substantially completely (i.e., preferably 90% of which, more preferably 95%o of which, most preferably 99% or more percent of which) exposed to the gaseous atmosphere.
  • the required dispersion of the solid particles according to the present invention may be achieved in one of many alternatives.
  • agitating e.g., by ultrasonic agitation
  • the tube or vessel in which the reaction takes place ensures the required dispersion.
  • performing a fluidized bed process in which the flow of gaseous atmosphere containing the chalcogen material(s) floats the particles during the reaction may account for proper dispersion of the solid particles (further details concerning the fluidized bed process may be found in Perry's Chemical Engineers Handbook, 1984).
  • the method of preparing IF particles according to the present invention is by a solid-gas phase reaction and is therefore less dependent upon reaction conditions such as gas flow and turbulence regimes, etc. as compared with the known gas-phase reaction. Furthermore, as is described in greater detailed herein below, yields of such solid gas phase reactions are exceptionally high, in many cases reaching substantially 100%, and the amount of product (i.e., IF particles) obtained is substantially unlimited since scaling-up such reactions, as opposed to gas-phase reactions, is fairly feasible, leading to the formation of macroscopic quantities of product.
  • step (b) of the method according to the present invention may be continued for a time and a temperature sufficient to allow the metal material and the chalcogen material to further react and form nested layers of metal chalcogenide.
  • the number of layers obtained using the method of the present invention is fairly unified since all particles are exposed to the same reaction conditions for a predetermined time period. This is however not the case using the prior art gas-phase reaction described hereinabove, since different particles sublime at different times after reaction starts.
  • supperlattice IF particles which are particles having layers of at least a first type and a second type metal chalcogenide (e.g., WS2 and WSe2, respectively), whereby a metal material, say WO3, is reacted with a first chalcogenide material, say H2S, and the product of this reaction is thereafter reacted with a second chalcogenide material, say H2Se.
  • a metal material say WO3
  • a first chalcogenide material say H2S
  • a second chalcogenide material say H2Se
  • supperlattices having layers of additional types of metal chalcogenide e.g., WTe2
  • alternating layers e.g., WS2, WSe2, WS2, WSe2, etc.
  • any other layer arrangement may be produced.
  • the method according to the present invention preferably includes a step in which the IF particles having one or two encaging layers of metal chalcogenides as described above are collected into a dense arrangement prior to continuing the reaction as described to obtain particles of nested layers.
  • the solid particles are first reacted such that they are covered by one or two layers of metal chalcogenide, the particles are then collected into a smaller volume (i.e., dense arrangement) and the reaction is continued until a desired number of nested layers encage the particles.
  • the size and shape of the solid metal material precursor particles Since by selecting the size and shape of the solid metal material precursor particles one is determining the size and shape of the IF-metal chalcogenide particles formed, a careful selection of sizes and shapes of the precursor particles is used according to the method of the present invention to tailor IF particles of various selected sized and shapes such as but not limited to spheres, sphere-like and nanotubes, according to any specific needs or requirements.
  • the size of the solid precursor particles and the reaction temperature with the chalcogen material gas are of great importance for the formation of the IF particles as opposed to other shapeless and amo ⁇ hous products (e.g., platelets). Therefore, the size of the solid particles is in the nanometer range, i.e. less than 300 nm, preferably less than 150 nm, most preferably less than 30 nm in, for example, diameter, and the reaction temperatures are typically maintained below 850 °C, depending on particle size.
  • the solid-gas reaction of the present invention may be carried out in a closed system containing the dispersed solid metal material particles and the chalcogen material reducing gaseous atmosphere, yet in a preferred embodiment of the invention, the reaction is carried out in an open system and the gaseous atmosphere is supplied in the form of a gas flow.
  • This architecture of the system ensures that the surface of each of the particles is constantly in contact with identical concentrations of the chalcogen material(s) in the gaseous atmosphere.
  • the open system may thus include an open tube in which the solid particles are dispersed and means to ensure flow of the described gaseous atmosphere.
  • the tube is preferably made of a heat resisting and chemically inert substance such as but not limited to quartz or a ceramic material, e.g., alumina, sapphire, zirconia, silicon carbide, tungsten carbide, etc.
  • a heat resisting and chemically inert substance such as but not limited to quartz or a ceramic material, e.g., alumina, sapphire, zirconia, silicon carbide, tungsten carbide, etc.
  • EXAMPLE 1 A solid (WO3)-gas (H2S+H2) reaction was carried out for the synthesis of sphere-like IF particles of WS2.
  • 100 mg of sphere-like WO3 powder (>99% pure) nanoparticles with particle sizes smaller than ca. 30 nm were carefully dispersed on the entire floor of a quartz tube reactor to avoid agglomeration and fusion of the heated nanoparticles, resulting in a substantial complete exposure of the nanoparticle surface to the reacting gas.
  • the reactor was inserted into an oven heated to 750 °C, in which a constant flow of forming gas (95% N 2 / 5% H 2 ; 1 10 cc/min) and H 2 S (2 cc/min) was provided.
  • Figs. 2A-2C wherein Fig. 2A shows the IF- WS2 nanoparticles recovered after 1 min, Fig. 2B after 10 min, and Fig. 2C after 30 min.
  • non-desired 2H-WS2 platelets were predominantly obtained under the following experimental conditions: (a) packing of the powder was too compact; (b) oxide precursor particles with sizes above 0.2 ⁇ m were used; and/or (c) reaction temperature exceeded 900 °C.
  • sphere-like WO3 powder (>99% pure) nanoparticles having particle size ⁇ ca. 20 nm (shown in Fig. 3 A) were carefully spreaded in a quartz tube reactor according to Fig. 6 herein, and sulfidized by heating the oven to to 700 °C under a constant flow of forming gas (95% N 2 / 5% H 2 ; 200 cc/min) and II 2 S (8 cc/min). The synthesis was stopped after 30 min and the IF-WS2 nanoparticles were recovered and examined by TEM.
  • the micrograph depicted in Fig. 3B shows that the IF-WS2 particles of Fig. 3B are evidently close in size and shape to the oxide particles of Fig. 3 A.
  • sphere-like WO3 powder (>99% pure) nanoparticles having particle size ⁇ ca. 50-150 nm (shown in Fig. 3C) were loosely dispersed in a reactor according to Fig. 6 herein, and the reactor was inserted into an oven heated to 830 °C under a constant flow of forming gas (95% N 2 / 5% II 2 ; 200 cc/min) and H 2 S (8 cc/min). After 90 min the black powder was retracted from the oven and examined by TEM.
  • IF-WS2 nanoparticles (Fig. 3D) of a similar size and shape to the oxide precursor nanoparticles (Fig. 3C) were obtained.
  • the H2S gas reacts uniformly with all oxide particles in the powder, and hence the number of sulfide layers is essentially the same for all intermediate IF-WS2/oxide composite nanoparticles obtained. Since the outer surface of the IF-WS2 layered material exposes only the basal plane of the compound, this material lends itself to solid lubrication applications. Indeed, IF nanoparticles do not stick to each other or the substrate and exhibit poor surface adhesion. Their approximate sphero-symmetric shapes imply easy sliding and rolling of the nanoparticles and consequently very small shear forces are required to move them on the substrate surface.
  • the oxide core provides the necessary mechanical toughness to the IF particles. Further, the potential of inorganic transition metal IF particles for photocatalysis is promising due to the strong optical abso ⁇ tion, large surface area and the documented chemical inertness under illumination (Tributsch, 1982).
  • TEM transmission electron microscopy
  • ED electron diffraction
  • XRD X-ray powder diffraction
  • XPS X-ray photoelectron spectroscopy
  • 100 mg of W0 3 powder (ca. 100 nm) were H 2 S annealed in a quartz tube reactor at 850 °C under a constant flow of forming gas (95% N 2 / 5% I I 2 ; 130 cc/min) and H 2 S (2 cc/min). Portions of the powder were taken for X-ray diffraction (XRD) measurements after various periods of time.
  • XRD X-ray diffraction
  • XRD spectra of powder samples acquired during different stages of the annealing process of WO 3 with H2S are shown in Fig. 4.
  • Curve A shows the XRD pattern of the WO3 precursor.As shown in curve B, after 2 minutes of annealing, a small WS2 peak is observed. Astonishingly, the entire nanoparticle core has been reduced to W I 8O49, at this early stage of the process. This fact can be understood assuming that hydrogen and water diffuse appreciably faster than sulfur diffuses to form sulfide.
  • Curve C shows the state of the sample after 8 minutes annealing, while curve D displays the XRD pattern of the sample after 15 minutes annealing time.
  • the XDR of the fully converted sample 120 minutes annealing time is shown in curve E.
  • the shift of the (0002) peak of the IF-WS2 phase indicates a lattice expansion of ca. 2% between two adjacent WS2 slabs along the c-axis, which is attributed to the strain in the bent layers (Feldman, 1995).
  • the layers cannot be fully commensurate. This discrepancy can be partially alleviated by lattice expansion along the c-axis.
  • EXAMPLE 5 The preparation of IF-WS2 was carried out as in Example 4. With reference now to Fig. 5, the transformation of WO3- x into IF-WS2, was further followed by optical abso ⁇ tion spectra using stirred alcoholic suspensions of samples drawn after 6 minutes and 120 minutes annealing time, as measured at room temperature. The oxide abso ⁇ tion peak of the composite oxide/sulfide (6 minutes annealing time) could be easily resolved in the difference spectrum and is substantially redshifted, compared to the literature value (Porter et al., 1969). Remarkably, IF-WS2 powder consisting of particles smaller than 10 nm, formed a stable alcoholic colloid exhibiting a strong blue shift of the excitonic abso ⁇ tion, which could be possibly assigned to a quantum size effect.
  • IF-WS2 The preparation of IF-WS2 was carried out as in Example 4. Being a surface sensitive technique, X-ray photoelectron spectroscopy (XPS) could be ideally suited for investigating the sulfide/oxide superstructure. Accordingly, few mg of IF-WS2 powder were pressed onto an indium plate, which provided the support and electrical contact for the powder. A sequence of four samples consisting of composite nanoparticles of IF-WS2 (shell)/tungsten oxide (core) at different annealing times were investigated: Sample 1 -- 2 minutes; sample 2 - 6 minutes; sample 3 -- 15 minutes; and sample 4 -- 2 hr annealing time. In addition, reference WS2 crystal, WO3 powder and a clean indium specimen were measured.
  • XPS X-ray photoelectron spectroscopy
  • the fraction of oxide particle converted into sulfide was determined in two independent ways, which gave similar results.
  • Shirley background subtraction was used for spectra analysis (Briggs and Seah, 1990). While the indium contribution to the total signal was less than 1%, carbon made up to 18% of the total material.
  • Insul stan d for the contributions from the top and bottom shells of the n tn segment (slope).
  • D n is the thickness of the oxide under the face of segment n.
  • ⁇ is the escape depth of the photoelectrons.
  • apparatus 10 includes a bundle of small tubes 12 arranged within a main tube 14, each of small tubes 12 serves to accommodate a preselected quantity of solid particles 16 of at least one metal material, as this term is defined hereinabove.
  • Apparatus 10 further includes a gas flux inlet 18 in main tube 14 for introducing a forming gas and at least one chalcogen material gas.
  • Apparatus 10 further includes heating means 20 for heating small tubes 12 and their content.
  • the preselected quantity of solid metal material particles is selected such that the solid particles are dispersed to a degree so that agglomeration and fusion of the solid particles into larger particles during heating are substantially avoided, so that the surface of the solid particles is substantially completely exposed to the chalcogen material gas.
  • apparatus 10 further includes first flow control means 22 for controlling the flow of the forming gas and second flow control means 24 for controlling the flow of the chalcogen material gas.
  • apparatus 10 is directed at increasing the amount of the reactant and expose its entire surface to the chalcogen and forming gases.
  • apparatus 10 typically, 1 g of IF-WS2 could be obtained in a single batch, with a conversion yield of almost 100%, the major loss occurring due to evaporation of the oxide prior to the conversion with the first layer of the sulfide.
  • Apparatus 30 includes a chamber 32 having a lower end 34 and an upper end
  • Chamber 32 is for accommodating solid particles 33 (e.g., a powder) of at least one metal material, say WO3, having the preselected size and shape.
  • Apparatus 30 further includes a gas penetrateable cover 38 covering at least a part of lower end 34 of chamber 30. Gas penetrateable cover 38 is for providing chamber 30 with an inward flow of a carrier gas as indicated by arrows 40. The inward flow of a carrier gas 40 is for floating solid particles 33 in chamber 30.
  • the carrier gas is a forming gas including N2 and H2 which also provides a reducing atmosphere within chamber 30.
  • Apparatus 30 further includes a gas outlet 42 located at upper end of the chamber for sustaining the flow of gas.
  • Apparatus 30 further includes first means 44 for introducing solid particles 33, WO3 in the given example, into chamber 30.
  • First means 44 may be in the form of a first inlet as shown in Figure 8, yet many other possible arrangements exist, as well known in the art.
  • Apparatus 30 further includes second means 46 for introducing at least one chalcogen material, say H2S, into chamber 30.
  • Second means 46 may be in the form of a second inlet 48, alternatively, cover 38 and gas flow 40 may serve as means 46.
  • carrier gas 40 includes also the chalcogen material, H2S in the given example.
  • Apparatus 30 further includes heating means 48 for heating chamber 30. In a preferred embodiment chamber 32 is heated to 650 °C - 850 °C.
  • apparatus 30 The operation of apparatus 30 is as follows. Solid particles 33 of transition metal material are fed into chamber 32 via first means 44 and gas flow 40 entering chamber 32 via cover 38 and leaving chamber 32 via outlet 42, ensures that solid particles 33 are floated and dispersed to a degree such that agglomeration and fusion of solid particles 33 into larger particles during heating by heating means 48 are substantially avoided, so that the surface of solid particles 33 is substantially completely exposed to the chalcogen material entering chamber 32 via second means 46, as described above. As a result IF metal chalcogenide particles are formed.
  • apparatus 30 is suitable both for batch preparations and continuous preparation of IF particles.
  • solid particles 33 are continuously fed into chamber 32 via first means 44 and gas flow 40 is maintained at a level strong enough to drive the particles out of chamber 32 via outlet 42.
  • gas flow 40 is maintained at a level strong enough to drive the particles out of chamber 32 via outlet 42.
  • the particles are within chamber 32, e.g.. 30 minutes, they are transformed into IF particles.
  • particles 33 are reacted within apparatus 30 for only few minutes (e.g., 1-2 minutes) during which a single or two layers of transition metal chalcogenide material are formed, after which the particles are collected into a dense arrangement and further reacted under otherwise similar conditions (atmosphere, temperature) to obtain additional layers.
  • apparatus 30 follows that of a circulating fluidized bed gas combustors, such as those described by Perry and Green (1984).

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Abstract

L'invention concerne un procédé et un appareil de préparation de nanoparticules d'un chalcogénure de métal, par exemple de métal de transition, de type fullerène inorganique présentant une taille et une forme voulue à hauts rendements et en quantités macroscopiques. Le procédé comprend les étapes consistant (a) à disperser des particules solides d'au moins une matière métallique non volatile ayant la taille et la forme présélectionnées, (b) à chauffer les particules solides de la matière métallique non volatile dans une atmosphère gazeuse réductrice contenant au moins un chalcogène pendant une durée et à une température suffisantes pour permettre au précurseur de la matière métallique et du chalcogène de réagir et de former au moins une couche de chalcogénure métallique, au moins une couche de chalcogénure métallique enrobant la surface de particules solides pour former les particules de type fullerène, (c) à recupérer les quantités macroscopiques ainsi obtenues du chalcogénure métallique IF(fullerène inorganique) de la forme et de la taille voulues.
PCT/IL1997/000165 1996-05-22 1997-05-22 Synthese en masse de structures de chalcogenures de metal de type fullerenes inorganiques WO1997044278A1 (fr)

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IL118378 1996-05-22

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WO2001066462A2 (fr) * 2000-03-06 2001-09-13 Yeda Research And Development Co. Ltd. Reacteurs pour la production de nanoparticules et nanotubes creux a base de disulfure de tungstene de type fullerene inorganique
WO2001066676A2 (fr) * 2000-03-06 2001-09-13 Yeda Research And Development Co. Ltd. Nanoparticules creuses du type fullerene, utilisees comme lubrifiants solides dans des matrices metalliques composites
WO2002030814A1 (fr) * 2000-10-10 2002-04-18 Institut "Jozef Stefan" Processus de synthese de nanotubes de dichalcogenures de metaux de transition
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FR2863265A1 (fr) 2003-12-04 2005-06-10 Centre Nat Rech Scient Procede de synthese de nanoparticules de chalcogenures ayant une structure lamellaire
WO2007010057A1 (fr) * 2005-07-15 2007-01-25 Consejo Superior De Investigaciones Científicas Nouveau systeme multitubulaire destine a la synthese de nanotubes de carbone en phase gazeuse
WO2006106517A3 (fr) * 2005-04-07 2007-02-08 Yeda Res & Dev Procede et appareil de production de nanoparticules inorganiques de type fullerene
WO2006123336A3 (fr) * 2005-05-17 2009-05-22 Yeda Res & Dev Films a coefficient de frottement reduit pour des applications dans des dispositifs medicaux et dentaires
WO2012042511A1 (fr) 2010-10-01 2012-04-05 Universita' Degli Studi Di Salerno SYNTHÈSE EN ENCEINTE UNIQUE DE NANOCRISTAUX 2D, 1D ET 0D DE CHALCOGÉNURES DE TUNGSTÈNE ET DE MOLYBDÈNE (WS2, MoS2) FONCTIONNALISÉS PAR UNE AMINE À LONGUE CHAÎNE ET/OU UN ACIDE CARBOXYLIQUE ET/OU UN THIOL
WO2015102006A1 (fr) * 2014-01-06 2015-07-09 Yeda Research And Development Co. Ltd. Attenuation d'incrustation de dispositifs medicaux au moyen de revêtements de nanoparticules inorganiques du type fullerene
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EP1840088A1 (fr) * 2000-03-06 2007-10-03 YEDA RESEARCH AND DEVELOPMENT Co. LTD. Nanoparticules et nanotubes creux à base de disulfide de tungstène de type fullerene-inorganique
WO2001066462A2 (fr) * 2000-03-06 2001-09-13 Yeda Research And Development Co. Ltd. Reacteurs pour la production de nanoparticules et nanotubes creux a base de disulfure de tungstene de type fullerene inorganique
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