WO2005062785A2 - Synthese en phase soluble de nanostructures d'oxydes metalliques - Google Patents

Synthese en phase soluble de nanostructures d'oxydes metalliques Download PDF

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WO2005062785A2
WO2005062785A2 PCT/US2004/042394 US2004042394W WO2005062785A2 WO 2005062785 A2 WO2005062785 A2 WO 2005062785A2 US 2004042394 W US2004042394 W US 2004042394W WO 2005062785 A2 WO2005062785 A2 WO 2005062785A2
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metal oxide
alcohol
water
nanometers
oxide nanostructure
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WO2005062785A3 (fr
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Edward T. Samulski
Bin Cheng
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The University Of North Carolina At Chapel Hill
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    • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
    • C01B13/14—Methods for preparing oxides or hydroxides in general
    • C01B13/36—Methods for preparing oxides or hydroxides in general by precipitation reactions in aqueous solutions
    • C01B13/366—Methods for preparing oxides or hydroxides in general by precipitation reactions in aqueous solutions by hydrothermal processing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
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    • C01—INORGANIC CHEMISTRY
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    • C01G1/02—Oxides
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    • C01G19/00—Compounds of tin
    • C01G19/02—Oxides
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    • C01G23/047—Titanium dioxide
    • C01G23/053—Producing by wet processes, e.g. hydrolysing titanium salts
    • C01G23/0536—Producing by wet processes, e.g. hydrolysing titanium salts by hydrolysing chloride-containing salts
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    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G25/00—Compounds of zirconium
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    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G9/00—Compounds of zinc
    • C01G9/02—Oxides; Hydroxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/20—Light-sensitive devices
    • H01G9/2027—Light-sensitive devices comprising an oxide semiconductor electrode
    • 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
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    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/77—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by unit-cell parameters, atom positions or structure diagrams
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    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
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    • C01P2004/00—Particle morphology
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    • C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM
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    • C01P2004/00—Particle morphology
    • C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
    • C01P2004/11—Particle morphology extending in one dimension, e.g. needle-like with a prismatic shape
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    • 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
    • C01P2004/12—Particle morphology extending in one dimension, e.g. needle-like with a cylindrical shape
    • 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
    • C01P2004/16—Nanowires or nanorods, i.e. solid nanofibres with two nearly equal dimensions between 1-100 nanometer
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    • C01P2004/00—Particle morphology
    • C01P2004/54—Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
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    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/542—Dye sensitized solar cells

Definitions

  • the presently disclosed subject matter pertains to metal oxide nanostructures, and to methods for preparing metal oxide nanostructures.
  • the presently disclosed subject matter provides a large-scale, single-step, direct hydrothermal method for preparing metal oxide nanostructures.
  • LED light emitting diode mA milliamperes meV milli-electron volts nm nanometer(s)
  • LEDs light-emitting diodes
  • single-electron transistors S. J. Tans, M. H. Devoret, H. Dai, A. Thess, R. E. Smalley, L. J. Gerrligs, C. Decker, Nature 1997, 386, 474; S. J. Tans, A. R. M. Verschueren, C. Dekker, Nature 1998, 393, 49
  • FETs field-effect transistors
  • nanolithographic techniques e.g., electron beam lithography, proximal probe patterning, and
  • the method comprises mixing a metal precursor solution with a basic solution to form a reaction mixture; and heating the reaction mixture in a closed container to provide a pressure greater than ambient pressure.
  • the method comprises collecting a metal oxide nanostructure from the reaction mixture.
  • Metal oxide nanostructures having a mean aspect ratio of at least about 4:1 and a cross-sectional width of about 100 nanometers or less are also disclosed. Accordingly, it is an object of the presently disclosed subject matter to provide a novel method of preparing metal oxide nanostructures.
  • An object of the presently disclosed subject matter having been stated hereinabove, which is addressed in whole or in part by the presently disclosed subject matter, other aspects and objects will become evident as the description proceeds when taken in connection with the accompanying Examples and Figures as best described herein below.
  • Figures 1A and 1 B are transmission electron microscopy (TEM) images of ZnO nanorods prepared in aqueous methanol (Fig. 1A) and aqueous ethanol (Fig. 1 B) at 150°C for 24 hrs as disclosed in the Examples.
  • TEM transmission electron microscopy
  • Figures 2A and 2B are plots showing X-ray diffraction (XRD) patterns of final ZnO nanorod products prepared in aqueous methanol (Fig. 2A) and aqueous ethanol (Fig. 2B) at 150°C as disclosed in the Examples.
  • Figures 3A and 3B are high-resolution transmission electron microscopy (HRTEM) images of ZnO nanorods prepared as disclosed in the Examples (scale bar, 5nm). In Fig. 3A the edge of a ZnO nanorod prepared in aqueous methanol is shown.
  • Fig. 3A the edge of a ZnO nanorod prepared in aqueous methanol is shown.
  • FIG. 3B the end of one of the ZnO nanorods prepared in aqueous ethanol is shown.
  • the results show that the ZnO nanorods grow along [0001] direction; the lattice spacing (2.56 ⁇ 0.05A) corresponds to the distance between two (0001 ) planes.
  • Figures 4A-4C are TEM images of 1-D ZnO nanostructures prepared as disclosed in the Examples, with different aspect ratios: (Fig. 4A) 5:1 ; (Fig. 4B) 20:1 ; (Fig. 4C) 100:1 (scale bars: 100nm, 250nm, and 1 m, respectively).
  • Figures 5A and 5B are TEM images of Sn0 2 nanorods prepared as disclosed in the Examples, with different aspect ratios: (Fig.
  • Figures 6A and 6B are 1-D and two-dimensional (2-D) lattices, respectively, of Sn0 2 nanorods prepared as disclosed in the Examples, with the [001] direction along the nanorod major axis (scale bars: 5nm in each).
  • Figure 7 is a plot showing XRD patterns of Sn0 2 nanorods prepared as disclosed in the Examples.
  • Figure 8 is a room temperature photo-luminescence spectrum of Sn0 2 nanorods prepared as disclosed in the Examples.
  • Figure 9 shows TEM images of 1-D Ti0 nanorods prepared as disclosed in the Examples (scale bar, 100nm).
  • Figure 10 is a plot depicting photocurrent-voltage characteristic of a solar cell made from Ti0 2 nanorods prepared as disclosed in the Examples.
  • Figure 1 1 is a schematic diagram of a photovoltaic device.
  • the term "about”, when referring to a value or to an amount of mass, weight, time, temperature, volume, concentration, and/or percentage, is meant to encompass variations of in one embodiment ⁇ 20%, in another embodiment ⁇ 10%, in another embodiment ⁇ 5%, in another embodiment ⁇ 1 %, in another embodiment ⁇ 0.5%, and in still another embodiment ⁇ 0.1 % from the specified amount, as such variations are appropriate to perform the disclosed methods.
  • the term “aspect ratio” refers to a ratio of the length of a nanostructure of the presently disclosed subject matter over the width of the nanostructure.
  • basic solution refers to a solution having a pH above 7.
  • the basic solution has a pH ranging from at least about 7.5 to at least about 14. In some embodiments, the basic solution has a pH of about 12.
  • metal precursor solution is meant to refer to a solution in which a metal is dissolved.
  • Representative metal compounds that can be dissolved in a metal precursor solution include metal salts, such as acetate salts, chloride salts, nitrate salts, isopropoxide salts and any other suitable salt that has desirable solubility characteristics.
  • the terms “one-dimensional” and “1-D” are used interchangeably and are meant to refer to a pattern of growth of a crystal structure that grows in a single direction from a starting point on or face of the crystal.
  • amorphous layer is meant to refer to a layer of non- crystalline material that forms on metal oxide crystal structures, including but not limited to on surfaces of metal oxide crystal structures, that is non- uniform as compared to the bulk crystal structure. Such layers may comprise catalyst residues used in typical processes currently available in the art for the production of metal oxide crystals.
  • nanostructure is meant to refer to any structure wherein at least one dimension of the structure is at the sub-micron, i.e., nanoscale range.
  • aprotic solvent refers to a solvent molecule which can neither accept nor donate a proton.
  • Typical aprotic solvents include, but are not limited to, acetone, acetonitrile, benzene, butanone, butyronitrile, carbon tetrachloride, chlorobenzene, chloroform, 1 ,2-dichloroethane, dichloromethane, diethyl ether, dimethylacetamide, A/, ⁇ /-dimethylformamide (DMF), dimethylsulfoxide (DMSO), 1 ,4-dioxane, ethyl acetate, ethylene glycol dimethyl ether, hexane, ⁇ /-methylpyrrolidone, pyridine, tetrahydrofuran (THF), and toluene.
  • Certain aprotic solvents are polar solvents.
  • polar aprotic solvents include, but are not limited to, acetone, acetonitrile, butanone, ⁇ /, ⁇ /-dimethylformamide, and dimethylsulfoxide.
  • Certain aprotic solvents are non-polar solvents. Examples of nonpolar, aprotic solvents include, but are not limited to, diethyl ether, aliphatic hydrocarbons, such as hexane, aromatic hydrocarbons, such as benzene and toluene, and symmetrical halogenated hydrocarbons, such as carbon tetrachloride.
  • protic solvent refers to a solvent molecule that contains a hydrogen atom bonded to an electronegative atom, such as an oxygen atom or a nitrogen atom.
  • Typical protic solvents include, but are not limited to, carboxylic acids, such as acetic acid, alcohols, such as methanol and ethanol, amines, amides, and water.
  • Zinc oxide (ZnO) is of interest in many applications, including transparent conductive coatings (T. Minami, J. Vac. Sci. Techno!. A 1999, 17, 1765) electrodes for dye-sensitized solar cells (H. Rensmo, K. Keis, H. Lindstr ⁇ m, S. S ⁇ dergren, A. Solbrand, A.
  • ZnO exhibits a direct bandgap of 3.37 eV at room temperature with a large exciton binding energy of 60 meV.
  • the strong exciton energy can ensure an efficient exciton emission at room temperature under low excitation energy (Y. Chen, D. M. Bagnall, H. Koh, K. Park, K. Hiraga, Z. Zhu, T. Yao, J. Appl. Phys. 1998, 84, 3912).
  • the synthesis of 1-D ZnO nanostructures has attracted considerable interest because of their promising applications in nanoscale optoelectronic devices.
  • Other metal oxide nanostructures that can exhibit tunable electrical, optical, magnetic and chemical properties are also of interest.
  • Titanium (IV) oxide (Ti0 2 ) is of similar interest.
  • III. Preparation Methods and Nanostructures Prepared by the Methods Small-diameter, single crystalline, one-dimensional (1 D) metal oxide nanostructures with different aspect ratios are synthesized by a solution phase method in accordance with the presently disclosed subject matter.
  • the nanostructures prepared by the presently disclosed subject matter exhibit a diameter ranging from about 3 nm to about 100 nm, in some embodiments, from about 10 nm to about 40 nm; and a length ranging from about 50 nm to several hundred nm, including up to about 10 ⁇ m long nanowires.
  • the metal oxide nanostructures in some embodiments, are characterized as pure hexagonal phase, c-axis grown single crystals.
  • a metal precursor e.g., a soluble salt such as zinc acetate dihydrate (Zn(Ac) 2 -2H 2 0)
  • a protic solvent e.g., methanol or ethanol
  • solutions of a basic solution e.g., a hydroxide solution
  • a protic solvent e.g., water, methanol and/or ethanol
  • the reaction mixture is transferred to a reaction vessel lined with a corrosion-resistant material, the reaction vessel is closed to provide an elevated pressure, and the reaction mixture heated for a period of time to form a precipitate.
  • the precipitate can then be collected, washed with a protic solvent, e.g., water and ethanol, and dried. .
  • the method is free of an active concentrating step, such as but not limited to a rotating evaporator step.
  • the metal precursor compound is typically provided at a concentration ranging from about 0.001 mol/L to 2 mol/L, including any desirable value there between, such as 0.01 mol/L, 0.1 mol/L, 0.5 mol/L, 1 mol/L, 1.5 mol/L and 2 mol/L.
  • Representative metals in the metal precursor solutions include but are not limited to zinc, tin, titanium, aluminum, barium, strontium, lead, zirconium, and combinations thereof.
  • a metal of any desired valence can be provided, such as, but not limited to, zinc (II), tin (II), tin (IV), and titanium (IV).
  • Representative combinations of metals for the metal oxide nanostructures include barium titanium oxide (BaTi0 3 ), strontium titanium oxide (SrTi0 3 ) and lead zirconium oxide (PbZrTi0 3 ), also referred to in the art as PZT.
  • the metal precursor solution in some embodiments, comprises a metal precursor compound dissolved in a protic solvent.
  • Representative protic solvents include water, alcohols, and combinations thereof.
  • Representative alcohols include but are not limited to methanol, ethanol, propanol, and other lower alkyl alcohols, e.g., Ci to C ⁇ alcohols.
  • the protic solvent can optionally comprise alcohol and water at a ratio ranging from about 0.01 :99.99 water to alcohol through about 100:0 water to alcohol, including any and all desirable values falling within this range.
  • Representative water to alcohol ratios thus including the following: about 1 :99, about 10:90, about 20:80, about 30:70, about 40:60, about 50:50, about 60:40, about 70:30, about 80:20, about 90:10, about 99:1 , about 99.99:0.01 , and about 100:0.
  • the basic solution comprises a hydroxide solution.
  • the hydroxide can be provided from a hydroxide compound selected from the group consisting of an organic hydroxide compound, an inorganic hydroxide compound, and combinations thereof.
  • Representative inorganic hydroxide compounds include, but are not limited to, sodium hydroxide and potassium hydroxide.
  • organic hydroxide compounds include, but are not limited it, tetramethyl ammonium hydroxide (TMAOH), tetraethyl ammonium hydroxide (TEAOH), tetrapropyl ammonium hydroxide (TPAOH), tetrabutyl ammonium hydroxide (TBAOH), tetrapentyl ammonium hydroxide (TPAOH).
  • TMAOH tetramethyl ammonium hydroxide
  • TEAOH tetraethyl ammonium hydroxide
  • TPAOH tetrapropyl ammonium hydroxide
  • TSAOH tetrabutyl ammonium hydroxide
  • TPAOH tetrapentyl ammonium hydroxide
  • the basic solution including, but not limited to, the hydroxide solution, can be prepared by dissolving the hydroxide compound in a protic solvent.
  • the protic solvent comprises water, alcohol, and combinations thereof.
  • Representative alcohols include but are not limited to methanol, ethanol, propanol, and other lower alkyl alcohols, e.g., Ci to C ⁇ alcohols.
  • the protic solvent can optionally comprise alcohol and water at a ratio ranging from about 0.01 :99.99 water to alcohol through about 100:0 water to alcohol, including any and all desirable values falling within this range.
  • Representative water to alcohol ratios thus including the following: about 1 :99, about 10:90, about 20:80, about 30:70, about 40:60, about 50:50, about 60:40, about 70:30, about 80:20, about 90:10, about 99:1 , about 99.99:0.01 , and about 100:0.
  • a typical basic solution has a pH ranging from about 7.5 to about 14, and in some embodiments the basic solution has a pH of about 8, 9, 10, 11 , 12, or 13.
  • the reaction mixture is heated in a closed container to provide a pressure greater than ambient pressure. In some embodiments, the heating provides a reaction temperature ranging from about 20°C to about 150°C, including but not limited to any desirable temperature therebetween.
  • Representative temperatures include but are not limited to 50°C, 60°C, 70°C, 75°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, and 150°C.
  • Representative heating profiles are disclosed in the Examples presented herein below. It is noted that these temperatures fall well below those temperatures observed in solid-state methodology for preparation of metal oxide crystals that is currently available in the art.
  • solid-state methodologies have reaction temperatures ranging on the order of about 800°C to about 1000°C. In some embodiments of the presently disclosed subject matter the heating occurs over a time period ranging from about 3 hours to about 24 hours, including any desired time therebetween.
  • the heating can occur for about 3 hours, for about 4 hours, for about 5 hours, for about 6 hours, for about 7 hours, for about 8 hours, for about 9 hours, for about 10 hours, for about 11 hours, for about 12 hours, for about 13 hours, for about 14 hours, for about 15 hours, for about 16 hours, for about 17 hours, for about 18 hours, for about 19 hours, for about 20 hours, for about 21 hours, for about 22 hours, for about 23 hours, and for about 24 hours.
  • the temperature is kept constant for the time period of the reaction.
  • the reaction container comprises a corrosion- resistant material.
  • a representative reaction container is lined with a corrosion- resistant material such as polytetrafluoroethylene (PTFE) sold under the registered trademark TEFLON® by E.I. DuPont deNemours & Co., Wilmington, Delaware, United States of America.
  • PTFE polytetrafluoroethylene
  • Heating in a closed container provides for a pressure in the container above ambient pressure.
  • any pressure elevation associated with heating in a closed container is meant to be encompassed by the phrase "pressure greater than ambient pressure”.
  • the pressure developed in the closed container is related to the solvents used, the percentage of the container filled with solvents, and the employed temperature (Richard I. Walton, Chem. Soc. Rev. 2002, 31, 230- 238).
  • the pressure can range from 0 to about 4000 bar, including any desirable pressure therebetween.
  • the metal oxide nanostructure is collected from the reaction mixture. Typically, yields on the order of 100% have been observed in accordance with the presently disclosed subject matter.
  • collecting the metal oxide nanostructure comprises collecting a precipitate.
  • the precipitate is collected, washed with a protic solvent and dried.
  • Representative protic solvents include but are not limited to water, and alcohol and combinations thereof.
  • Representative alcohols include but are not limited to methanol, ethanol, propanol, and other lower alkyl alcohols, e.g., Ci to C ⁇ alcohols.
  • nanostructure is meant to refer to any structure wherein at least one dimension of the structure is at the sub- micron, i.e., nanoscale range. In some embodiments at least one dimension of the nanostructure is less than one micrometer, or 1 ,000 nanometers. In some embodiments at least one dimension of the nanostructure is less than 500 nanometers. In some embodiments at least one dimension of the nanostructure is less than 100 nanometers. In some embodiments the at least one dimension is less than 25 nanometers. In some embodiments the at least one dimension of the nanostructure is less than 10 nanometers. In some embodiments the at least one dimension of the nanostructure is less than 5 nanometers.
  • At least one dimension of a metal oxide nanostructure of the presently disclosed subject matter comprises a cross- sectional width.
  • a metal oxide nanostructure of the presently disclosed subject matter can have a cross-sectional width of about 100 nanometers or less, about 50 nanometers or less, about 25 nanometers or less, about 10 nanometers or less, or even about 5 nanometers or less.
  • the cross-sectional width comprises a circular or polygonal cross-section and the cross-sectional width is measured by a nominal diameter.
  • Representative embodiments of the presently disclosed subject matter can have a cross-section with a nominal diameter ranging from about 3 nanometers to about 100 nanometers, including any desirable width therebetween, such as but not limited to about 3 nanometers, about 5 nanometers, about 10 nanometers, about 15 nanometers, about 20 nanometers, about 25 nanometers, about 30 nanometers, about 35 nanometers, about 40 nanometers, about 45 nanometers, about 50 nanometers, about 55 nanometers, about 60 nanometers, about 65 nanometers, about 70 nanometers, about 75 nanometers, about 80 nanometers, about 85 nanometers, about 90 nanometers, about 95 nanometers, and about 100 nanometers.
  • a metal oxide nanostructure of the presently disclosed subject matter can have an overall length dimension of about 50 nanometers or less, including but not limited to 45, 40, 35, 30, 25, 20, 15, 10, or 5 nanometers or less.
  • the nanostructure can be referred to as a nanorod.
  • a representative metal oxide nanostructure of the presently disclosed subject matter can have a length of 50 nanometers or greater, including about 100 nanometers, about 250 nanometers, about 500 nanometers, about 750 nanometers, and even over 1 ,000 nanometers into the micron length range. In this latter case, the nanostructure can be referred to as a nanowire.
  • the length of the nanostructure can exceed 1 micron, another dimension, such as cross- sectional width, can be maintained in the nanoscale range, as discussed hereinabove.
  • the aspect ratio of a metal oxide nanostructure of the presently disclosed subject matter can be controlled depending on the combination of solvents employed in the reaction.
  • a metal oxide nanostructure of the presently disclosed subject matter can have a mean aspect ratio of at least 4.1 , and indeed can have a mean aspect ratio ranging from at least about 4:1 to at least 100:1. Any desirable aspect ratio between this range is also provided, including 5:1 , 10:1 , 20:1 , 50:1 , and any other aspect ratio that might be desirable and as would be apparent to one of ordinary skill in the art after a review of the present disclosure.
  • the presently disclosed methods do not employ a solid substrate, wherein the substrate would be seeded or not seeded, and/or do not employ a solid substrate and a blocking agent such as but not limited to citrate.
  • the nanostructures prepared in accordance with the presently disclosed subject matter are individual, unattached and suspended in the reaction mixture.
  • a metal oxide nanostructure of the presently disclosed subject matter can have a single crystalline structure. The single crystalline structure while inherently three- dimensional can be further described as one-dimensional as one growth direction is preferred and leads to an anisometric nanostructure. Additionally, the metal oxide nanostructures of the presently disclosed subject matter are substantially pure.
  • a surface of a metal oxide nanostructure of the presently disclosed subject matter is substantially free of an amorphous layer, such as but not limited to an amorphous surface layer.
  • substantially free of an amorphous layer it is meant that an amorphous layer is not detectable by standard detection approaches, such as observation by transmission electron microscopy, including high-resolution transmission electron microscopy.
  • a substantially pure metal oxide nanostructure does not include an amorphous layer that is detectable by a standard observation technique.
  • the presently disclosed methods do not require high temperatures, catalysts, or special and expensive equipment, which other synthesis methods in the art, e.g., chemical vapor deposition (CVD), thermal evaporation, molecular beam epitaxy (MBE), and high-temperature vapor transport process, require.
  • the presently disclosed methods also address, in some embodiments, aggregation of the nanostructure after evaporation of the solvent, by using capping agents to form a passivation layer on the surface of the as-prepared nanostructures to obtain a single nanorod or nanowire when the nanostructures are redispersed in solution. IV.
  • the metal oxide nanostructures provided by the presently disclosed subject matter can be used as active components or interconnects in fabricating nanoscale electronic, optical, optoelectronic, electrochemical, and electromechanical devices. These nanostructures can be applied to light-emitting diodes (LEDs), single-electron transistors, field-effect transistors (FETs), flat-panel displays (FPDs), biological and chemical sensors, photodetectors, electron emitters, and ultraviolet nanolasers.
  • the metal oxide nanostructures can also be used as transparent conductive coatings, electrodes for dye-sensitized solar cells, gas sensors, and electro- and photo-luminescent materials.
  • a photovoltaic device comprising a metal oxide nanostructure of the presently disclosed subject matter.
  • the nanostructure may be a nanorod or a nanowire, depending on the structural features of the photovoltaic device. Structures that can be used in a photovoltaic device are known in the art and can be employed in conjunction with a metal oxide nanostructure of the presently disclosed subject matter upon a review of the disclosure herein by one of ordinary skill in the art.
  • Cell 10 comprises, in operative orientation, glass 1 ; transparent Indium-doped tin oxide film 2; platinum catalyst film 3; seal 4; electrolyte 5; and dye-impregnated Ti0 2 nanostructure film 6; and load 8.
  • a system or device comprising cell 10 can comprise light source 7, which can be used to direct light to cell 10.
  • the precursor was dissolved in a mixture of water and alcohols (methanol, ethanol, propanol).
  • the ratio of water/alcohol can be in the range of (about 0.01 to about 50)/(about 99.9 to about 50) on a volume/volume basis.
  • the prepared precursor solution was mixed with a basic solution with a high pH value (e.g. a pH of about 12).
  • the latter basic solution can be prepared using a hydroxide compound, such as but not limited to a hydroxide compound selected from the group consisting of sodium hydroxide (NaOH), tetramethyl ammonium hydroxide (TMAOH), tetraethyl ammonium hydroxide (TEAOH), tetrapropyl ammonium hydroxide (TPAOH), tetrabutyl ammonium hydroxide (TBAOH), tetrapentyl ammonium hydroxide (TPAOH), and combinations thereof.
  • a hydroxide compound selected from the group consisting of sodium hydroxide (NaOH), tetramethyl ammonium hydroxide (TMAOH), tetraethyl ammonium hydroxide (TEAOH), tetrapropyl ammonium hydroxide (TPAOH), tetrabutyl ammonium hydroxide (TBAOH), tetrapentyl ammonium hydroxide (TPAOH), and combinations thereof.
  • Figure 1 shows transmission electron microscopy (TEM) images of 1-D ZnO nanorods with controllable aspect ratios.
  • 10 mL of 0.1 M of zinc acetate stock solution in methanol was mixed with 20 mL of 0.5 M NaOH solution in methanol to get a clear solution which was transferred to a PTFE-lined (such as that available from E.I. DuPont deNemours & Co., Wilmington, Delaware, United States of America, under the registered trademark TEFLON®) stainless steel autoclave and heated at 150 ° C for 24 hours.
  • the reaction procedure in ethanol medium was the same.
  • the water to methanol ratio was 0.01 to 99.9.
  • the reaction was conducted at 150 ° C for 24 hrs.
  • the water to ethanol ratio was 0.01 to 99.9.
  • the reaction was conducted at 150 ° C for 24 hrs. Characterization.
  • Fig. 2 shows X-ray diffraction patterns from final products prepared in methanol (Example 1A) and ethanol (Example (1B). The diffraction peaks are quite similar to those of bulk ZnO, which can be indexed as the hexagonal wurtzite structure of ZnO.
  • the water to methanol ratio was 10 to 90. Reaction conducted at 150 ° C for 24 hrs.
  • the water to methanol ratio is 30 to 70. Reaction conducted at 150 ° C for 24 hrs.
  • Examples 1A, 1B, 2A, 2B and 2C No evidence for oriented attachment of particles was found even at the primary stage of growth. This observation suggests that 1-D ZnO growth along the c-axis under hydrothermal condition is related to both its intrinsic crystal structure and external factors. ZnO is a polar crystal. The overall shape and aspect ratio of crystals are determined by the relative rates of growth of its various faces. In general the growth rate of a face will be controlled by a combination of internal, structurally-related factors (intermolecular bonding preferences or dislocations), and external factors (supersaturation, temperature, solvents and impurities) (N. Kubota, Cryst. Res. TechnoL, 2001 , 36, 749).
  • EXAMPLE 3 Synthesis Of SnO 2 Nanorods In Solution This Example discloses a solution route to single-crystalline Sn0 2 nanorods with dimensions approaching those of molecules (diameter ⁇ 3.4 nm).
  • a Sn 4+ precursor SnCI 4 ⁇ 5H 2 0, 0.001 mol
  • the clear solution with dissolved precursor was transferred to a PTFE (e.g., TEFLON®-brand, DuPont)-lined stainless steel autoclave and heated at 150 ° C for 24 hrs.
  • a white-gray precipitate was collected, purified and dried in air at ambient temperature with a yield of approximately 100%.
  • Tin precursors that were used included: tin chloride (SnCI -5H 2 0) and tin isopropoxide. 0.001 mol/L to 2 mol/L Sn 4+ solutions.
  • the precursor was dissolved in mixture of water and alcohols (methanol, ethanol, propanol).
  • the ratio water/alcohol can be in the range of (about 0.01 to about 10)/(about 99.9 to about 90) on a volume/volume basis.
  • the prepared precursor solution was mixed with a basic solution with high pH value (e.g., pH of about 12).
  • the latter basic solution can be prepared using a hydroxide compounds, such as but not limited to a hydroxide compound selected from the group consisting of sodium hydroxide (NaOH), tetramethyl ammonium hydroxide (TMAOH), tetraethyl ammonium hydroxide (TEAOH), tetrapropyl ammonium hydroxide (TPAOH), tetrabutyl ammonium hydroxide (TBAOH), and combinations thereof.
  • NaOH sodium hydroxide
  • TMAOH tetramethyl ammonium hydroxide
  • TEAOH tetraethyl ammonium hydroxide
  • TPAOH tetrapropyl ammonium hydroxide
  • TSAOH tetrabutyl ammonium hydroxide
  • the combined solution with both precursor and basic compounds was put in a PTFE (TEFLON® brand, DuPont)-lined reactor, sealed to withstand an increase in pressure, and maintained at constant temperature (which might be any value in the range of 20 ° C to 150 ° C) for 3 to 24 hours (for example, any amount of time within this range).
  • Product. The white-grey precipitate product was obtained and purified by washing with water several times. The separation of the white precipitate from water can be done by centrifugation.
  • the aspect ratios of the one-dimensional (1-D) Sn0 2 nanostructures can be controlled by changing the alcohol and/or the ratio of water to alcohol. Examples 3A and 3B.
  • Figures 5A and 5B show transmission electron microscopy (TEM) images of 1-D Sn ⁇ 2 nanorods with controllable aspect ratios.
  • Figures 6A and 6B show high-resolution TEM results indicating that all of these nanorods with different aspect ratios are single-crystalline.
  • FIG. 6A is a wide-field TEM image of the Sn0 2 nanorods that clearly indicates that the product is entirely comprised of a relatively uniform, rod-like morphology (15 - 20 nm rod lengths and 2.5 - 5 nm rod diameters).
  • the lattice fringes in the HRTEM image ( Figure 6B) further confirm the single-crystal nature of the Sn0 2 nanorods.
  • the spacing between adjacent lattice planes is 0.337 nm, corresponding to (110) planes of rutile Sn0 2 , which indicates that the preferential growth direction is [001].
  • the mean rod length (17 + 4 nm) and diameter (3.4 ⁇ 0.6 nm) were extracted from TEM image of more than 300 nanorods.
  • Figure 7 shows the powder XRD- pattern from the as-prepared product.
  • FIG. 8 shows the room temperature photoluminescence spectrum of the as-prepared Sn0 2 nanorods. A red emission at 580 nm was observed from the Sn0 2 nanorods using a He-Cd laser ( ⁇ 325 nm) as the excitation source.
  • the low energy emission might be related to crystal defects or defect levels associated with oxygen vacancies, or tin interstitials that have formed during growth. However, this does not impact overall purity. Some defects of this nature (e.g. vacancies) can arise during crystal growth prepared by various methods, such as solution phase growth, high- temperature thermal evaporation, chemical vapor deposition or laser ablation.
  • small diameter, single-crystalline Sn0 2 nanorods were prepared in solution at low temperature without using catalysts.
  • the single- crystalline Sn0 2 nanorods show a mean aspect ratio of 4:1 with the [001] direction along the major axis.
  • the optical measurements further show that the Sn0 2 nanorods possess surface characteristics that generate a red emission band that can be exploited in gas sensors or other optoelectronic devices.
  • Titanium (IV) isopropoxide 0.001 mol/L to 2 mol/L Ti 4+ solutions.
  • the precursor was dissolved in mixture of water and alcohols (methanol, ethanol, propanol).
  • the ratio water/alcohol can be in the range of (about 100 to about 50)/(about 0 to about 50) on a volume/volume basis.
  • the prepared precursor solution was mixed with a basic solution with high pH value (a pH of about 12).
  • the latter basic solution can be prepared using a hydroxide compound, such as a hydroxide compound selected from the group consisting of sodium hydroxide (NaOH), tetramethyl ammonium hydroxide (TMAOH), tetraethyl ammonium hydroxide (TEAOH), tetrapropyl ammonium hydroxide (TPAOH), tetrabutyl ammonium hydroxide (TBAOH), tetrapentyl ammonium hydroxide (TPAOH), and combinations thereof.
  • a NaOH solution was used. Reaction.

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Abstract

L'invention porte sur un procédé de préparation de nanostructures d'oxydes métallique consistant à mélanger une solution précurseur avec une solution basique pour former un mélange réactif, puis à chauffer le mélange réactif dans une enceinte close pour y produire une pression supérieure à la pression ambiante. L'invention porte également sur des nanostructures d'oxydes métallique présentant un allongement moyen d'au moins environ 4:1, et une largeur de section transversale d'environ 100 manomètres ou moins.
PCT/US2004/042394 2003-12-17 2004-12-17 Synthese en phase soluble de nanostructures d'oxydes metalliques WO2005062785A2 (fr)

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CN101786652A (zh) * 2010-02-26 2010-07-28 上海理工大学 一种端凹陷的氧化锌纳米棒的制备方法
CN101805017A (zh) * 2010-04-08 2010-08-18 洛阳师范学院 一种金红石型二氧化钛纳米粒子的制备方法
DE102009030476A1 (de) * 2009-06-24 2011-01-05 Universität Bremen Verfahren zum Herstellen eines Halbleiterbauelementes mit einer Nanodrahtschicht, Halbleiterbauelement und Verwendung desselben
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CN102219254A (zh) * 2011-06-20 2011-10-19 厦门大学 一种氧化锌纳米棒的制备方法
CN101559921B (zh) * 2009-06-02 2011-12-28 河南大学 气相沉积制备二氧化锡纳米带的方法和装置
CN102336431A (zh) * 2011-06-28 2012-02-01 西北大学 一种SnO2花状结构纳米材料及其水热制备方法
CN103332726A (zh) * 2013-06-20 2013-10-02 上海大学 二氧化锡纳米材料的水热合成方法
CN103332727A (zh) * 2013-06-26 2013-10-02 宁波今心新材料科技有限公司 氧化锡纳米晶制备方法
CN104609460A (zh) * 2015-01-29 2015-05-13 武汉大学 一种长度可控的纳米氧化锌及其制备方法
CN105784776A (zh) * 2016-03-15 2016-07-20 上海海洋大学 一种基于SnO2纳米线传感器及其制备方法和应用
CN108249473A (zh) * 2018-02-09 2018-07-06 黑龙江大学 一种棒束状氧化锌气敏材料的制备方法及其应用

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US7943106B2 (en) 2005-03-18 2011-05-17 Antaria Limited Rare earth nanorods
WO2006096936A1 (fr) * 2005-03-18 2006-09-21 Advanced Nanotechnology Limited Nanobâtonnets d'un métal des terres rares
AU2006225095B2 (en) * 2005-03-18 2011-09-08 Antaria Limited Rare earth nanorods
CN101559921B (zh) * 2009-06-02 2011-12-28 河南大学 气相沉积制备二氧化锡纳米带的方法和装置
DE102009030476B4 (de) * 2009-06-24 2011-11-10 Universität Bremen Verfahren zum Herstellen einer p-leitenden Schicht für ein Halbleiterbauelement, Verfahren zum Überführen einer p-leitenden Nanodrahtschicht und Verfahren zum Herstellen eines Halbleiterbauelementes
DE102009030476A1 (de) * 2009-06-24 2011-01-05 Universität Bremen Verfahren zum Herstellen eines Halbleiterbauelementes mit einer Nanodrahtschicht, Halbleiterbauelement und Verwendung desselben
CN101786652A (zh) * 2010-02-26 2010-07-28 上海理工大学 一种端凹陷的氧化锌纳米棒的制备方法
CN101805017A (zh) * 2010-04-08 2010-08-18 洛阳师范学院 一种金红石型二氧化钛纳米粒子的制备方法
CN101805017B (zh) * 2010-04-08 2011-06-15 洛阳师范学院 一种二氧化钛纳米粒子的制备方法
CN102219254A (zh) * 2011-06-20 2011-10-19 厦门大学 一种氧化锌纳米棒的制备方法
CN102336431B (zh) * 2011-06-28 2014-03-26 西北大学 一种SnO2花状结构纳米材料及其水热制备方法
CN102336431A (zh) * 2011-06-28 2012-02-01 西北大学 一种SnO2花状结构纳米材料及其水热制备方法
CN103332726A (zh) * 2013-06-20 2013-10-02 上海大学 二氧化锡纳米材料的水热合成方法
CN103332727A (zh) * 2013-06-26 2013-10-02 宁波今心新材料科技有限公司 氧化锡纳米晶制备方法
CN104609460A (zh) * 2015-01-29 2015-05-13 武汉大学 一种长度可控的纳米氧化锌及其制备方法
CN105784776A (zh) * 2016-03-15 2016-07-20 上海海洋大学 一种基于SnO2纳米线传感器及其制备方法和应用
CN108249473A (zh) * 2018-02-09 2018-07-06 黑龙江大学 一种棒束状氧化锌气敏材料的制备方法及其应用
CN108249473B (zh) * 2018-02-09 2020-06-23 黑龙江大学 一种棒束状氧化锌气敏材料的制备方法及其应用

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