US20100258759A1 - Nanostructured Metal Oxides Comprising Internal Voids and Methods of Use Thereof - Google Patents
Nanostructured Metal Oxides Comprising Internal Voids and Methods of Use Thereof Download PDFInfo
- Publication number
- US20100258759A1 US20100258759A1 US12/303,668 US30366807A US2010258759A1 US 20100258759 A1 US20100258759 A1 US 20100258759A1 US 30366807 A US30366807 A US 30366807A US 2010258759 A1 US2010258759 A1 US 2010258759A1
- Authority
- US
- United States
- Prior art keywords
- nanostructure
- nanostructures
- metal oxide
- nanostructured
- shell
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
-
- 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
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
-
- 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
- C01G1/02—Oxides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G19/00—Compounds of tin
- C01G19/02—Oxides
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/40—Electric properties
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
-
- 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
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- 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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
-
- 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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
- Y10T428/2984—Microcapsule with fluid core [includes liposome]
-
- 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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
- Y10T428/2991—Coated
-
- 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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
- Y10T428/2991—Coated
- Y10T428/2993—Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]
Definitions
- the present invention relates to nanostructures and more particularly to nanostructures comprising nanostructured metal oxide shells enclosing internal voids, as well as methods for making and using the same.
- nanostructures comprising metal oxides may be used as semiconductors in applications such as gas sensors and lithium rechargeable batteries.
- metal oxides for example, tin oxide (SnO 2 )
- metal oxides generally have a much higher theoretical specific lithium storage capacity area than more traditionally used materials such as graphite
- the large volume changes in metal oxide nanostructures during charging/discharging processes result in poor cyclability, thus limiting their use in such applications.
- Hollow nanostructures have higher surface to volume ratios which allow for greater charge capacities than solid nanostructures.
- Hollow nanostructures may be designed in various shapes and sizes, and commonly include nanoparticles, nanorods/belts/arrays, nanotubes, nanocylinders, nanococoons, nanodisks, nanoboxes, nanospheres, among others.
- the present invention relates to nanostructures of metal oxides, comprising a nanostructured shell defining an internal space, internal cavity, or “internal void.”
- the nanostructures may be nanoparticles, nanorods/belts/arrays, nanotubes, nanocylinders, nanodisks, nanoboxes, nanospheres, nanococoons, nanospindles, among other nanostructures.
- the nanostructure comprises a metal oxide nanosphere comprising an outer shell defining a completely hollow cavity.
- the nanostructure comprises a inner hollow cavity comprising an internal core.
- the nanostructures comprise two or more nanostructured metal oxide concentric shells surrounding an inner cavity, while in another embodiment, such nanostructured metal oxide concentric shells surrounding the inner space are in turn separated by intervening spaces.
- the nanostructures may comprise a plurality of pores in one or more of the nanostructured walls.
- the nanostructures comprise additional materials in the inner space, for example, materials bearing magnetic or electrical properties, for example ferric oxides including, but not limited to, Fe 2 O 3 , Fe 3 O 4 , CoFe 2 O 4 , as well as other metal oxides like CO 3 O 4 , ZnO, CuO, Cu 2 O, or even metal sulfide semiconductors like CdS, ZnS, etc.
- the inner space of the nanostructures of the invention may comprise cores of varying sizes of the template material used.
- the nanostructures are made of tin oxides, but may also comprise oxides of titanium, zirconium, boron, aluminum, germanium, indium, gallium, hafnium, silicon, vanadium, or tantalum, zinc, copper, iron, nickel, copper and combinations thereof.
- the present invention is directed to novel inexpensive, viable, high-yield methods for large-scale and industrial mass production of such hollow metal oxide nanostructures.
- the invention comprises a template-free “one-pot” method, based on an inside-out Oswald ripening mechanism. This method comprises hydrothermal treatment of a metal-oxide precursor in a mixed solvent, usually a polar solvent in and water, and the mediation of general ionic and non-ionic surfactants, polymers, or crystal modifiers such as urea-based compounds at temperatures above about 140° C. and up to about 200° C. that allow for high-yield mass production of hollow metal oxide nanostructures with controllable sizes in the range of 200.0-500.0 nm.
- the invention is drawn to a novel hydrothermal shell-by-shell templating strategy suitable for the preparation of polycrystalline monodisperse metal oxide hollow nanostructures with nanostructured metal oxide shells.
- the hydrothermal shell-by-shell templating method of the invention requires no prior surface modification of the template, making this method both easier to use and less costly than existing methods.
- the metal oxide hollow nanostructures are multi-shelled which leads to greater physical stability.
- these single or multi-shelled nanostructures are functionalized with other functional nanoparticles (e.g., materials with magnetic properties, materials with good heat and electrical conductivity properties, etc.).
- the deposition protocol taught by the invention can be applied to a variety of template materials, including both silica and non-silica templates, and to templates having varying shapes, sizes and symmetries.
- the nanostructures produced by this method may be coated with additional magnetic or semiconductor materials.
- FIGS. 1A , B, and C depicts a cross-sectional schematic diagram of nanostructures comprising various shell-like structures enclosing a hollow internal void.
- FIG. 2A depicts the ring-like selected area electron diffraction pattern (“SAED”) pattern shown by the SnO 2 in the nanostructured shell.
- FIG. 2B depicts the rutile tetragonal structure of SnO 2 .
- FIG. 2C is a magnified energy filtered Transmission electron microscope (“TEM”) image of a SnO 2 nanosphere.
- SAED selected area electron diffraction pattern
- FIG. 3 illustrates cross-sectional diagrams of the inside-out ripening mechanism that forms the basis of the one-pot template-free synthesis of a metal oxide hollow nanostructure.
- FIG. 4 illustrates the shell-by-shell template-based method of preparing a SnO 2 nanosphere.
- FIG. 5 depicts cavity functionalization of a nanosphere with an Au nanoparticle.
- FIGS. 6A and 6B depict TEM images of Au/silica core/shell particles and double-shelled Au/SnO 2 hollow colloids prepared via steps I and II of FIG. 5 , respectively;
- FIG. 6C shows Au/SnO 2 hollow colloids obtained by HF etching the colloids shown in FIG. 5B ;
- FIG. 6D depicts the EDX spectrum of the particles shown in FIG. 5 .
- FIG. 7A depicts a first cycle charge-discharge curve for SnO 2 hollow nanospheres.
- FIG. 7B illustrates the comparative cycling performance of various nanostructures.
- FIG. 8 illustrates cyclic voltammograms of hollow SnO 2 nanospheres (first and second cycle).
- the hollow nanostructures of the present invention comprise one or more polycrystalline metal oxide nanostructured shells enclosing an inner cavity or “internal void.”
- the terms cavity and void are interchangeable.
- Various metal oxides may be employed in the invention, including, but not restricted to oxides of titanium, zirconium, boron, aluminum, germanium, indium, gallium, hafnium, silicon, vanadium, tin, tantalum, iron, nickel, cobalt, zinc, copper and combinations thereof.
- the metal oxides may be tin oxide (SnO 2 ), titanium dioxide (TiO 2 ), and zirconium oxide (ZrO 2 ). More preferably, the metal oxide is SnO 2 .
- the hollow nanostructures as taught by the invention exhibit various configurations, including, but not limited to, nanoparticles, nanorod/belts/arrays, nanotube, nanodisks, nanoboxes, nanocylinders, nanospheres, nanococoons and nanospindles, among others.
- the hollow nanostructures of the invention are symmetrical, in that they comprise at least one axis of symmetry; in other embodiments, the hollow nanostructures may be asymmetrical.
- the nanostructures of the invention comprise shell-like structures enclosing a hollow internal void.
- These nanostructures include, but are not limited to:
- the shells may be in direct contact with each other at one or more points on their respective surfaces, in full contact at all points on their respective adjacent surfaces, or may be separated by an intervening void.
- the intervening void may be completely hollow or may comprise an additional material.
- the average cross-sectional distance of the nanostructure may vary between about 50.0 nm to about 1,000.0 nm, more particularly between about 100.0 nm and about 700.00 nm, and still more particularly between about 200.0 nm and about 500.0 nm.
- the average thickness of the nanostructured shells may vary from about 10.0 nm and 50.0 nm, more particularly between about 15.0 nm and 40.0 nm, and still more particularly between about 20.0 nm and about 30.0 nm.
- the core typically comprises an average diameter of between about 50.0 nm and 500.0 nm, more particularly between about 200.0 nm and about 400.0 nm, and still more particularly between about 75.0 nm and about 125.0 nm.
- the nanostructures of the invention may comprise a single pore or a plurality of pores within one or more of the nanostructured shells.
- the pores may be present in any nanostructured shell anywhere on said shell.
- the term pore may be construed as a hole of any shape or size across the entire thickness of a nanostructured shell.
- the pores may be present in only one nanostructured shell, all nanostructured shells, or a subset of the nanostructured shells.
- the pores are present in only the outermost shell.
- the pores are present in every shell.
- a pore in one nanostructured shell may be contiguous with a pore in an adjacent nanostructured shell.
- a pore across each nanostructured shell is contiguous with a pore in the adjacent concentric shell such that the contiguous pores create an opening from the exterior of the nanostructure to the internal void.
- pores in the nanostructured shells may be macroporous pores with pore dimensions less than about 2.0 nm, macroporous with pore dimensions typically greater than about 50.0 nm, or mesoporous with pore dimensions between 2.0 and 50.0 nm.
- the pores in the nanostructured shells diameters between about 1.0 nm and about 10.0 nm, more particularly between about 3.0 nm and about 5.0 nm.
- a single-shelled nanostructure may comprise a single macropore of sufficient diameter such that the resulting nanostructure resembles a cup or a bowl.
- the presence of contiguous macropores in a multi-shelled nanostructure may result in a similar cup or bowl-like nanostructure.
- the pores are formed by treating the nanostructure with a pore-forming material (porogen) followed by heating between 100 and 1,000° C. C. V. Nguyen et al., Chem. Mater. 11, 3080 (1999); C. Nguyen et al., Macromolecules 33, 4281 (2000). Heat may be applied at high temperatures in an autoclave. Alternately, the porogen-treated nanostructure may be dried at low temperatures ( ⁇ 0° C.) in a lyophilizer.
- the nanostructured shells of the invention are polycrystalline, typically comprising a plurality of tin oxide primary metal oxide “crystallites,” which may vary in size.
- the average size of these primary crystallites is between about 1.0 nm and about 50.0 nm, more particularly between about 10.0 nm and about 20.0 nm.
- X-ray diffraction patterns (“XRD”) conducted on a nanostructure comprising SnO 2 nanostructured shells confirm the polycrystalline nature of the nanostructured shells.
- the SAED pattern shown in FIG. 2A indicates that the nanostructures are polycrystalline and the diffraction rings from inside to outside can be indexed to (110), (101), (200), (211) and (112) planes of rutile SnO 2 , respectively.
- the diffraction rings come from different crystal planes, with each crystal plane in a primary crystal generating a point in the SAED pattern.
- the rutile tetragonal structure of SnO 2 typically looks like the structure depicted in FIG. 2B , where the Sn atom is octahedrally surrounded by oxygen atoms, which, in turn, are surrounded by planar triangles of Sn atoms.
- the cross-structural morphology of the metal oxide nanostructures of the invention are further illustrated by a low magnification transmission electron microscopy (“TEM”) image as shown in FIG. 2C .
- TEM transmission electron microscopy
- the SnO 2 nanospheres clearly depict the nanostructured outer shell 300 , the inner space 304 and an internal core 306 .
- the dark contrast inside each shell as shown in FIG. 2C reveals that the inner space is in fact filled with a solid core.
- Such nanostructures can be prepared using a template-free as well as the template-based methods taught by the invention and discussed herein.
- controlled synthesis of the foregoing nanostructures may be carried out by a simple “one-pot” template-free manner or by using templates and employing a shell-by-shell deposition of the metal oxide.
- the one-pot template-free method based on a novel and unusual “inside-out Ostwald ripening mechanism” comprises the steps of combining metal oxide precursor with a solvent to create a mixture, optionally adding one or more yield-enhancing additives (fore example, urea-based additives) to this mixture, and heating this mixture for a predetermined reaction times. These steps may be followed by cooling, centrifugation and washing with deionized water.
- This one-pot, template-free method taught by the invention is highly advantageous over existing methods in that it involves fewer steps than existing methods suitable for high-yield mass production of mono-disperse, structurally sound metal oxide nanospheres.
- this template-free method has been shown to give high yield mass production of SnO 2 hollow nanospheres as measured by the % of Sn units in the stannate precursor converted to SnO 2 crystallites in the end-product, and at nearly 100% morphological yield (i.e., the percentage of nanospheres displaying the same size, shape and cross-sectional characteristics).
- the precursor salt of the metal oxide is an alkali metal precursor salt, more preferably the alkali metal precursor salt is a sodium or a potassium salt, most preferably the potassium salt.
- the metal precursor salts may be sodium stannate or potassium stannate.
- the mixed solvent typically comprises a polar solvent in water, preferably a highly polar solvent with some degree of hydrophobic/surfactant character, more preferably, any C 2 to C 10 alcohol which may be employed as a single component or in mixture with other additives.
- the yield-enhancing additives used in the method comprise urea compounds (such as urea and thiourea), —NH 2 compounds (including, but not limited to ammonia, ethylenediamine, surfactants amines, diamines, ammonia, and hydrazine), or surfactants, both ionic and non-ionic (for example, cetyltrimethylammortium bromide (“CTAB”), Tween-based compounds, dodecyl sulfates, etc.).
- CTAB cetyltrimethylammortium bromide
- yield-enhancing additives are urea-based catalytic additives such as urea and thiourea.
- Additional yield-enhancing additives including ammonia, ethylenediamine and surfactants such as cetyltrimethylammortium bromide (“CTAB”) may be used during synthesis.
- ammonia may be used as a pH modifier.
- Ethylenediamine and the CTAB surfactant may be used to effect the shape and size of the end product.
- the mixture of the metal-oxide precursor in the mixed solvent and the yield enhancing additives is heated to a temperature of between 140 and 200° C., preferably between 3 and 24 hours
- a hollow SnO 2 nanosphere by heating a mixture of potassium stannate in a mixed ethanol/water solvent in the presence of urea, the mechanism for the template-free formation of hollow nanostructures may be described.
- solid nanospheres are formed by hydrolysis of the stannate. With prolonged hydrothermal treatment, these solid nanospheres are transformed by the “inside-out Ostwald ripening” or “core evacuation” of the formed solid nanosphere in which the metal oxide crystals inside the solid nanosphere are forced out of the solid nanosphere to create an internal void.
- Ostwald ripening is a well-known particle (crystal) growth mechanism, in which the growth of large particles occurs at the expense of small ones while trying to minimize the surface energy (because of the smaller surface to volume ratio in large particles).
- inside-out Ostwald ripening is understood to be the process by which the metal oxide crystals in the interior of the nanostructures dissolve preferentially because of the crystallization of the metal oxides on the surface of the forming nanostructures, even as the more amorphous material within the interior of the nanostructure amorphous tend to dissolve.
- This inside-out ripening process may initiate at regions either just below the external surface of the solid nanosphere, or around the nanostructure center, depending on the reaction conditions.
- Core evacuation by either mechanism yields, respectively, hollow nanostructures or hollow nanostructures in which the internal void comprises a solid core.
- the solid nanospheres typically formed first are not typically single-crystalline but comprise many tin oxide primary crystallites, the tin oxide particles in the inner region are packed more loosely than those in the outer layer resulting in larger surface energies which can lead to the tendency to dissolve.
- the primary particles in the outer surfaces are relatively easy to crystallize facilitated by surrounding solvent, and therefore less crystalline particles in the inner region are easy to dissolve.
- FIG. 3A illustrates cross-sectional diagrams of the proposed inside-out ripening mechanism: inside-out evacuation can initiate from just below surface of the shell 300 to form nanostructure (i) in which the hollow inner void 304 is beginning to be formed; then evolve to form a nanostructure (ii) with a well-defined inner void 304 further comprising an inner core 306 ; and further to hollow nanostructure (iii). Alternately, inside-out ripening mechanism may start around the central region of the solid sphere and evolve to particle (iii) directly.
- the shape, size, morphology, and yield of the resulting metal oxide nanostructure may be determined.
- These parameters include, but are not limited to, the type and concentration of the metal-oxide precursor, the properties of the polar solvent and the polarity of the resultant polar solvent/water mixture, the type and amount of yield-enhancing additives used, the temperature at which the mixing reaction is conducted, and the length of time for which this reaction is performed.
- changes in precursor concentration affect both the morphology and size of the end-product.
- the precursor concentration of potassium stannate was reduced from 8.4 mM to 4.7 mM, the product comprised discrete hollow nanospheres with diameters in the range of 50.0 nm to 200.0 nm and a shell thickness of 10.0 nm.
- a higher precursor concentration e.g.
- nanospheres comprising a core spaced apart from and surrounded by a shell at approximately the same thickness (10.0 nm), but with larger diameters, for example, between about 300.0 and about 400.0 nm as well as a highly defined inner core within the internal void.
- the solvent is preferably a highly polar solvent with some degree of hydrophobic/surfactant character, more preferably, any C 2 to C 10 alcohol which may be employed as a single component or in mixture with other additives.
- the polar solvents are dissolved in water to create a mixed solvent
- the ratio of C 2 to C 10 alcohol to water used is 1:1, but ratios may range from 5:1 to 1:4 to produce similar results.
- the r value (EtOH v/v % in the solvent of EtOH/H 2 O) or polarity of the mixed solvent is a parameter which has an effect on the resultant metal oxide nanostructures.
- the preferred r values are in the range of 30-50%.
- well-defined hollow nanospheres are difficult to produce when r is lower than 30%.
- the precursor concentrations must be increased than what are required for higher r values.
- the products comprise mixtures of single hollow nanospheres (100-250 nm) and aggregated nanospheres at a precursor concentration of 13.5 mM, well-defined hollow nanospheres (300-550 nm) at a precursor concentration of 16.5 mM, and bowl-like large hollow spheres (450-750 nm) at a precursor concentration 19.5 mM, respectively.
- urea-based catalytic additives such as urea and thiourea was found to increase both the product yield (measured by the % of Sn units in the stannate precursor converted to SnO 2 crystallites in the end-product) and morphological yield to nearly 100%.
- product yield measured by the % of Sn units in the stannate precursor converted to SnO 2 crystallites in the end-product
- morphological yield to nearly 100%.
- hollow SnO 2 nanospheres produced in the presence of urea, keeping all other reaction parameters the same are well dispersed with good monodispersity (usually 80-200 nm in diameter and an average shell thickness of about 20 nm).
- temperature of the reaction can be varied to affect changes in shape, size and morphology.
- product synthesized at 150° C. comprises monodispersed hollow nanospheres with sizes in the range of 350-460 nm, while those prepared at 180° C. assume a bowl-like shape at a similar size.
- the hydrothermal reaction period was shown to affect the final product.
- the size of the SnO 2 nanospheres obtained in the presence of thiourea at different hydrothermal reaction times do not typically increase with longer reaction times, their shell thicknesses may decrease from ⁇ 50 nm to ⁇ 20 nm, illustrating the continuing evacuation of SnO 2 nanospheres thus increasing the size of the inner void, while at the same time decreasing the thickness of the nanostructured shell.
- Other time-dependent experiments in which all other synthesis conditions except reaction times were kept identical the size distribution of the nanospheres appeared largely unaltered, while the morphology changed. Specifically, the product comprised solid nanospheres after a reaction time of 6 hours, and hollow nanospheres when allowed to react for 24 hours.
- the present invention also teaches a novel template based shell-by-shell nanostructure synthesis. Unlike existing methods of preparing nanostructures, the shell by shell synthesis taught by the invention creates nearly mono-disperse, narrow-size distribution, hollow nanostructures.
- the deposition protocol involves direct treatment of the template with the metal oxide precursor in the presence of a mixed solvent and a catalyst which creates a polycrystalline nanostructured metal oxide shell over the template.
- the method may be used to create a single nanostructured shell, while in other embodiments, the deposition protocol is successively repeated to create two or more polycrystalline nanostructured shells such that each newly created shell surrounds the prior formed shell.
- the shell-by-shell deposition protocol as taught by the invention may be used on any suitable template including, but not restricted to, templates made of silica, latex, carbon, gels, micelles, or combinations thereof.
- the shell-by-shell deposition protocol may also be used on templates of any shape, including, but not restricted to, spherical, polyhedral, cylindrical templates as well as any other symmetrical or asymmetrical templates. It has also been shown that the shell-by-shell synthesis as taught by the invention can work on template sizes in which the size of the template as measured by its longest cross-sectional distance is between 50.0 to 1,000.0 nm, preferably between 150.0 to 500M nm, and more preferably between 200.0 to 300.0 nm.
- the shell-by-shell synthesis of the invention may be illustrated by the formation of polycrystalline SnO 2 nanospheres as depicted in FIG. 4 .
- the SnO 2 precursor is first hydrothermally deposited on silica nanospheres to form a single nanostructured shell 300 as shown in Step 1.
- This single nanostructured shell then serves as an interim nanotemplate for further deposition.
- This deposition step may be repeated to form double shells 308 as shown in Step 2.
- the double-shelled nanostructures still contain partially dissolved silica cores 306 , the sizes of which may be controlled by “etching” (or dissolution) with dilute HF (typically about 1-2% wt %) to form either a hollow inner void 304 with an internal core 306 comprising the unetched template material (Step 3), or proceed to form a completely hollow inner void 306 (Step 4).
- Double-shelled hollow nanostructures can also be formed in a single step by increasing the relative amount of silica template (Step 5). By increasing the extent of HF etching, the double-shelled hollow nanostructures can be transformed into a single shell hollow nanostructure (Step 6).
- the hydrothermal deposition of SnO 2 is carried out under basic conditions at a pH between 9 and 12, more preferably between 10 and 11.
- the precursor salt of the metal oxide is an alkali metal precursor salt, more preferably the alkali metal precursor salt is a sodium or a potassium salt, most preferably the alkali metal precursor salt is a potassium salt.
- the metal precursor salts may be sodium stannate or potassium stannate.
- the mixed solvent typically comprises a polar solvent in water, preferably a highly polar solvent with some degree of hydrophobic/surfactant character, more preferably, any C 2 to C 10 alcohol which may be employed as a single component or in mixture with other additives.
- the yield-enhancing additives used in the method comprise urea compounds (such as urea and thiourea), —NH 2 compounds (including, but not limited to ammonia, ethylenediamine, surfactants amines, diamines, ammonia, and hydrazine), or surfactants, both ionic and non-ionic (for example, cetyltrimethylammortium bromide (“CTAB”), Tween-based compounds, dodecyl sulfates, etc.)
- CTAB cetyltrimethylammortium bromide
- yield-enhancing additives are urea-based additives such as urea and thiourea.
- ammonia may also be used as a pH modifier.
- Ethylenediamine and the CTAB surfactant may be used to effect the shape and size of the end product.
- the mixture of the metal-oxide precursor and the template in the mixed solvent (and optionally the yield enhancing additive)s is heated in an autoclave to a temperature of between 100 and 1000° C., preferably between 120 and 200° C., most preferably between 140 and 180° C.
- the synthesis was found to have an optimal precursor concentration.
- silica template amounts of 100 to 160 mg, more preferably 120 to 140 mg result in single-shelled nanostructures.
- the amount of silica template is reduced from 120 mg to 80 mg, some double-shelled nanostructural formation is observed, but only in the form of irregular SnO 2 crystallites. Only when the amount of silica template is further reduced to between 30 and 50 mg, more preferably 40 to 45 mg, are well-formed double-shelled hollow nanostructures observed.
- the size of the inner cavity may be controlled by the extent of HF etching. For instance, for those double-shelled nanostructures bearing an internal silica core, continuous HF etching leads to the greater dissolution of the inner silica core and the simultaneous enlargening of the inner cavity, while also causing the dissolution of the nanostructured double-shell into a single shell.
- L. Archer, X. W. Lou, Small 2006 0000, 00, No. 0 1-5 Manuscript available at www.small-journal.com).
- the structural integrity of a single-shelled nanostructure may be enhanced either by the creation of one or more additional shells or by a post-synthesis annealing process carried out at temperatures between 400 to 600° C., more preferably between 500 and 550° C. Alternately, structural integrity may also be enhanced by increasing the deposition temperature from a range of about 140 to 160° C. to between 180 to 200° C.
- the present invention allows for the exploitation of the single or multi-shelled hollow nanostructures by functionalizing the inner cavity with potentially useful nanoparticles.
- the inner cavities may be functionalized with magnetic nanoparticles by first coating the nanoparticle with the template material.
- Magnetic nanoparticles include, but are not limited to, nanoparticles comprising ferric oxides including, but not limited to, Fe 2 O 3 , Fe 3 O 4 , CoFe 2 O 4 , as well as other metal oxides like CO 3 O 4 , ZnO, CuO, Cu 2 O, or even metal sulfide semiconductors like CdS, ZnS, etc.
- the template material may include any suitable material that may be coated onto said magnetic nanoparticle.
- Template materials include, but are not limited to, latex, silica, gels, carbon, or combinations thereof.
- Such functionalized nanostructures with magnetized functionalities may be used in applications such as targeted drug delivery, separation methods, biomedical imaging, and use in photovoltaic cells among others.
- SnO 2 is deposited on an ⁇ -Fe 2 O 3 nanosphere, nanococoon, or nanospindle by the shell-by-shell synthesis taught by the invention to form the corresponding uniform multi-shelled SnO 2 nanostructure.
- noble metals including, but not limited to Au, Ag, Pt, Pd, etc. are treated with a template material and then subjected to a metal oxide shell-by-shell nanostructure synthesis as taught by the invention to create a mixed metal/metal oxide nanostructure functionalized to serve a particular end use.
- the functional metal is gold, while the metal oxide is SnO2.
- a mixed Au—SnO2 metal-semiconductor composite nanostructure is created that is suitable for use in applications such as sensors, catalysts, controlled release drug delivery systems and bioseparations.
- FIG. 5 The process by which an Au nanoparticle is functionalized within a hollow SnO 2 nanostructure is shown in FIG. 5 .
- Step 1 involves the conformal coating of Au nanoparticles 310 with uniform shells of silica 312 .
- the as-obtained Au/silica nanoparticle are then used as the template for subsequent SnO 2 deposition to form a SnO 2 shell 300 in Step II.
- FIGS. 6A and 6B depict TEM images of Au/silica core/shell particles 400 and double-shelled Au/SnO 2 hollow colloids 402 prepared via steps I and II of FIG. 5 , respectively;
- FIG. 6C shows Au/SnO 2 hollow colloids obtained by HF etching the colloids shown in FIG. 5B ;
- FIG. 6D depicts the energy dispersive X-ray (“EDX”) spectrum of the particles shown in FIG. 5B .
- EDX energy dispersive X-ray
- the polycrystalline metal oxide nanostructures of the invention generated by the methods taught herein, may also be coated with additional industrially useful materials.
- the metal oxide nanostructures of the invention may serve as templates to be coated with materials bearing electrical conductivity properties, where optionally the metal oxide nanostructures bear electrical conductivity properties as well.
- the metal oxide nanostructures are SnO 2 nanostructures that are coated with semiconductors including, but not limited to, propylenevinylidenefluoride (“PVDF”), hexafluoropropylenevinylidenefluoride semiconductor (“PVDF-HFP”), and carbon-black filled PVDF or PVDF-HFP.
- PVDF propylenevinylidenefluoride
- PVDF-HFP hexafluoropropylenevinylidenefluoride semiconductor
- carbon-black filled PVDF or PVDF-HFP carbon-black filled PVDF or PVDF-HFP.
- the metal oxide nanostructured materials of the present invention may be used in a variety of applications.
- the materials may be utilized as nanoscale chemical reactors, catalysis and photocatalysts, photovoltaic devices and as the anode in lithium storage batteries.
- nanostructured SnO 2 made in accordance with the present invention exhibits enhanced electrochemical properties.
- One hindrance against use of Sn-based anode materials in lithium ion batteries is the large volume change exhibited by Sn-based particles, owing to particle shattering and agglomeration during charging/discharging processes which leads to poor cyclability.
- the hollow nanostructures of the invention mitigate this problem.
- SnO 2 nanostructures of the present invention exhibit initial discharge capacities between about 1000.0 mAh/g and 1,300 mAh/g and more particularly between about and about 1,100 and 1,200 mAh/g and still more particularly greater than 1,100 mAh/′g.
- the nanostructures may undergo between about 25 and 45 cycles and more particularly between about 30 and 40 cycles while still functioning effectively at a discharge capacity of at least 300 mAh/g. It is believed that the superior lithium storage capacity is associated with the unique structure of hollow nanospheres with porous shells formed during the inside-out evacuation process.
- Hollow SnO 2 nanoparticles were prepared by a hydrothermal method in an ethanol/H 2 O mixed solvent.
- Potassium stannate trihydrate K 2 SnO 3 ; 3H 2 O, Aldrich, 99.9%
- K 2 SnO 3 3H 2 O, Aldrich, 99.9%
- a slightly white translucent or clear solution was obtained, which was then transferred to a 40 mL Teflon-lined stainless steel autoclave.
- urea, thiourea or ethyl diamine were also used as additives, typically with overall concentrations of about 0.1 mM.
- the autoclave was gradually cooled down in air, or rapidly using tap water.
- the white product was harvested by centrifugation and washed with deionized water and ethanol before drying at 50° C. overnight.
- the electrochemical properties of the hollow SnO 2 nanospheres were characterized at room temperature. For these measurements SnO 2 nanospheres were used to form the negative electrode in rechargeable lithium-ion batteries.
- the working electrode comprised 80 wt % of the active material (hollow SnO 2 ), 10 wt % of conductivity agent (carbon black, Super-P), and 10 wt % of binder (polyvinylidene difluoride, PVDF, Aldrich).
- Lithium foil was used as the counter and reference electrodes.
- the electrolyte was 1 M Li PF 6 , in a 50:50 w/w mixture of ethylene carbonate and diethyl carbonate.
- FIG. 7A shows the first cycle charge-discharge curve of SnO 2 hollow nanospheres 500. It is apparent from FIG.
- FIG. 7A compares the cycling performance of as-prepared SnO 2 hollow nanospheres of the invention (curve a) 502 with pristine SnO 2 hollow nanospheres synthesized in accordance with the methods outlined in J. Power Sources 2005, 144, 220 by Wang and Lee (curve c) 506 and previous SnO 2 hollow nanospheres synthesized in accordance with the methods outlined in Y. Wang et al., Chem. Mater, 2006, 18, 1347 (curve b) 504 , which were all tested under similar conditions. It is apparent from this figure that the cycling performance of the SnO 2 hollow nanospheres of the present invention is superior.
- the capacity of the SnO 2 hollow nanospheres of the invention is still comparable to the theoretical capacity of SnO 2 after more than 30 cycles; and much higher than the theoretical capacity of graphite after more than 40 cycles.
- FIG. 8 illustrates cyclic voltammograms of hollow SnO 2 nanospheres (first and second cycle). The scan range of 0-1.5 V (vs. Lithium) was swept at the rate of 0.1 mV/s).
- Monodisperse silica nanospheres with different sizes were prepared from the well known Stobers method. W. Stober, A. Fink, E. Bohn, J. Colloid Interface Sci. 1968, 26, 62-69. Polycrystalline SnO 2 shells were facilely deposited on silica templates without any prior surface modification by a hydrothermal method. Depending on the amount of nanostructures desired, 40-120 mg silica nanospheres were first dispersed by ultrasonication in 30 ml of ethanol/water (37.5 vol % ethanol) mixed solvent.
- urea 0.8% g or 0.5 M
- potassium stannate trihydrate ⁇ 144 mg or 16 mM; K 2 SnO 3 .3H 2 O, Aldrich, 99.9%
- the suspension was transferred to a 40 ml Teflon-lined stainless-steel autoclave, which was then heated in an airflow electric oven at 150-190° C. for 36 hours.
- the white product was harvested by centrifugation and washed with deionized water. This hydrothermal SnO 2 deposition can be repeated to form double and even triple shells.
- the silica core was etched in a dilute ethanol/water solution of HF ( ⁇ 2%).
- the Au/silica core/shell particles were prepared as described in detail by Liu et al. S. H. Liu, M. Y. Han, Adv. Funct. Matter. 2005, 15, 961-967. After extensive washing with water, the as-obtained Au/silica core/shell particles ( ⁇ 50 mg) were directly used without drying as the template for the same SnO 2 deposition.
- ⁇ -Fe 2 O 3 spindles were prepared by aging a solution of 0.02 M FeCl 3 and 0.45 mM NaH 2 PO 4 at 105° C. for 48 hours as described by Ozaki et al. M. Ozaki, S. Kratohvili, E. Matijevic, J. Colloid Interface Sci., 1984, 102, 146-151.
- 63 mg ⁇ -Fe 2 O 3 spindles were first dispersed by ultrasonication in a mixture consisting 650 mL of 2-propanol and 65 mL of deionized water, followed by 60 mL of ammonia (29.6%).
- TEOS tetraethylorthosilicate
- 2-propanol 10% v/v
- the reaction was then continued for 18 hours.
- the ⁇ -Fe 2 O 3 /SiO 2 particles were harvested by centrifugation, and washed with ethanol and water several times before being vacuum-dried at room temperature.
- 118 mg ⁇ -Fe 2 O 3 /SiO 2 particles were dispersed in 25 mL of ethanol/water (37.5 vol % ethanol) mixed solvent.
- urea (0.75 g) and potassium stannate trihydrate (113 mg; K 2 SnO 3 .3H 2 O, Aldrich (St. Louis, Mo.), 99.9%) were added.
- the suspension was transferred to a 40 mL Teflon-lined stainless-steel autoclave, which was then heated in an air flow electric oven at 170° C. for 36 hours. After the autoclave was allowed to cool down naturally, the particles were washed with ethanol/water once before the same hydrothermal deposition was repeated.
- ⁇ -Fe 2 O 3 /SiO 2 particles were used for synthesis of porous double-shelled nanococoons.
- the silica was dissolved in 1 M NaOH solution at 50° C. for about 2 days (alternately, the silica is dissolved by etching in a very diluted HF solution as SnO 2 tends to partially dissolve in NaOH solution when exposed to NaOH for extended periods of time).
Abstract
The present invention relates to nano structures of metal oxides having a nanostructured shell (or wall), and an internal space or void. Nanostructures may be nanoparticles, nanorod/belts/arrays, nanotubes, nanodisks, nanoboxes, hollow nanospheres, and mesoporous structures, among other nanostructures. The nanostructures are composed of polycrystalline metal oxides such as SnO2. The nanostructures may have concentric walls which surround the internal space of cavity. There may be two or more concentric shells or walls. The internal space may contain a core such ferric oxides or other materials which have functional properties. The invention also provides for a novel, inexpensive, high-yield method for mass production of hollow metal oxide nanostructures. The method may be template free or contain a template such as silica. The nanostructures prepared by the methods of the invention provide for improved cycling performance when tested using rechargeable lithium-ion batteries.
Description
- The present application claims priority to U.S. Provisional Pat. App. 60/804,031 filed on Jun. 6, 2006, the contents of which are hereby incorporated by reference in their entirety.
- This invention was made with Government support under contract number DMR 0404278, awarded by the National Science Foundation. The government has certain rights in this invention.
- The present invention relates to nanostructures and more particularly to nanostructures comprising nanostructured metal oxide shells enclosing internal voids, as well as methods for making and using the same.
- Recently, hollow inorganic micro- and nanostructures have attracted considerable attention because of their promising applications as nanoscale chemical reactors, catalysts, drug delivery carriers, semiconductors, and photonic building blocks. X. W. Lou, C. Yuan, Q. Zhang, L. A. Archer, Angew. Chem. Int. Ed. 2006, 45, 3825. In particular, nanostructures comprising metal oxides may be used as semiconductors in applications such as gas sensors and lithium rechargeable batteries. Y. Wang, X. Jiang, Y. Xia, J. Am. Chem. Soc. 2003, 125, 16176; M. Law, H. Kind, B. Messer, F. Kim, P. Yang, Angew. Chem. Int. Ed. 2002, 41, 2405; Y. Idota, T. Kubota, A. Matsufuji, Y. Maekawa, T. Miyasaka, Science, 1997, 276, 1395. However, although metal oxides (for example, tin oxide (SnO2)) generally have a much higher theoretical specific lithium storage capacity area than more traditionally used materials such as graphite, the large volume changes in metal oxide nanostructures during charging/discharging processes result in poor cyclability, thus limiting their use in such applications. S. Han, B. Jang, T. Kim, S. M. Oh, T. Hyeon, Adv. Funct. Mater. 2005, 15, 1845; K. T. Lee, Y. S. Jung, S. M. Oh, J. Am. Chem. Soc. 2003, 125, 5652; Y. Wang, H. C. Zeng, J. Y. Lee, Adv. Mater. 2006, 18, 645. One possible strategy to mitigate this problem and further enhance structural stability is to use hollow nanostructures. Such hollow nanostructures have higher surface to volume ratios which allow for greater charge capacities than solid nanostructures. Hollow nanostructures may be designed in various shapes and sizes, and commonly include nanoparticles, nanorods/belts/arrays, nanotubes, nanocylinders, nanococoons, nanodisks, nanoboxes, nanospheres, among others.
- At present, there exist numerous methods for the preparation of hollow metal oxide nanostructures. One approach involves the use of various removable or sacrificial templates, including, for example, monodispersed silica, carbon or polymer latex spheres, reducing metal nanoparticles, and even emulsion droplets/micelles and gas bubbles. Q. Peng, Y. Dong, Y. Li, Angew. Chem. Int. Ed. 2003, 42, 3027-3030. Although conceptually simple and versatile, such methods are often burdened with the challenge of uniformly depositing metal oxides (or their precursors) on templates, a problem which has traditionally been dealt by prior surface modification, itself a tedious process. M. Yang, J. Ma, C. Zhang, Z. Yang, Y. Lu, Angew. Chem. Int. Ed. 2005, 44, 6727. Other templating methods such as templating sol-gel precursors with colloidal crystals or their replicas (often called the “lost-wax approach”) result in amorphous and structurally fragile nanostructures upon crystallization at high temperatures and upon template removal. Z. Zhong, Y. Yin, B. Gates, Y. Xia, Adv. Mater. 2000, 12, 206-209.
- Other approaches, which are template free, employ mechanisms such as corrosion-based inside out evacuation and the nanoparticle Kirkendall effect. Y. D. Yin, R. M. Rioux, C. K. Erdonmez, S. Hughes, G. A. Somorjai, A. P. Alivisatos, Science 2004, 304, 711. However, many such existing methods for the production of nanostructures are often cumbersome involving multiple steps that are often difficult to control, and are cost-prohibitive which prevent them from being used in large-scale applications. Moreover, many of these existing methods also result in poor yields of mono-disperse, hollow nanostructures, producing mixed hollow and solid nanostructures, or nanostructures with large-size distributions.
- Thus, there exists a need for improved hollow metal oxide nanostructures comprising a relatively high surface to volume ratio (and thus a large number of potential active sites) and physical stability. There also exists a need for viable industrially scaleable methods of producing such hollow metal oxide nanostructures at low cost, high yields, narrow-size dispersions, geometric stability and homogeneous morphologies.
- In one aspect, the present invention relates to nanostructures of metal oxides, comprising a nanostructured shell defining an internal space, internal cavity, or “internal void.” The nanostructures may be nanoparticles, nanorods/belts/arrays, nanotubes, nanocylinders, nanodisks, nanoboxes, nanospheres, nanococoons, nanospindles, among other nanostructures. In one embodiment, the nanostructure comprises a metal oxide nanosphere comprising an outer shell defining a completely hollow cavity. In another embodiment, the nanostructure comprises a inner hollow cavity comprising an internal core. In yet another embodiment, the nanostructures comprise two or more nanostructured metal oxide concentric shells surrounding an inner cavity, while in another embodiment, such nanostructured metal oxide concentric shells surrounding the inner space are in turn separated by intervening spaces. In yet another embodiment, the nanostructures may comprise a plurality of pores in one or more of the nanostructured walls. In other embodiments, the nanostructures comprise additional materials in the inner space, for example, materials bearing magnetic or electrical properties, for example ferric oxides including, but not limited to, Fe2O3, Fe3O4, CoFe2O4, as well as other metal oxides like CO3O4, ZnO, CuO, Cu2O, or even metal sulfide semiconductors like CdS, ZnS, etc. Materials with other functional properties, including noble metals, like Au, Ag, Pt, Pd, etc., may also be enclosed within the inner space of the nanostructures of the invention. When the nanostructures are synthesized using templates comprising silica, latex, carbon, or gels, the inner space of the nanostructure may comprise cores of varying sizes of the template material used. In preferred embodiments, the nanostructures are made of tin oxides, but may also comprise oxides of titanium, zirconium, boron, aluminum, germanium, indium, gallium, hafnium, silicon, vanadium, or tantalum, zinc, copper, iron, nickel, copper and combinations thereof.
- In another aspect, the present invention is directed to novel inexpensive, viable, high-yield methods for large-scale and industrial mass production of such hollow metal oxide nanostructures. In one embodiment, the invention comprises a template-free “one-pot” method, based on an inside-out Oswald ripening mechanism. This method comprises hydrothermal treatment of a metal-oxide precursor in a mixed solvent, usually a polar solvent in and water, and the mediation of general ionic and non-ionic surfactants, polymers, or crystal modifiers such as urea-based compounds at temperatures above about 140° C. and up to about 200° C. that allow for high-yield mass production of hollow metal oxide nanostructures with controllable sizes in the range of 200.0-500.0 nm.
- In yet another aspect, the invention is drawn to a novel hydrothermal shell-by-shell templating strategy suitable for the preparation of polycrystalline monodisperse metal oxide hollow nanostructures with nanostructured metal oxide shells. Unlike existing methods, the hydrothermal shell-by-shell templating method of the invention requires no prior surface modification of the template, making this method both easier to use and less costly than existing methods. In one embodiment, the metal oxide hollow nanostructures are multi-shelled which leads to greater physical stability. In another embodiment, these single or multi-shelled nanostructures are functionalized with other functional nanoparticles (e.g., materials with magnetic properties, materials with good heat and electrical conductivity properties, etc.). The deposition protocol taught by the invention can be applied to a variety of template materials, including both silica and non-silica templates, and to templates having varying shapes, sizes and symmetries. In one embodiment, the nanostructures produced by this method may be coated with additional magnetic or semiconductor materials.
- Certain embodiments of the present invention are illustrated by the accompanying figures. It should be understood that the figures are not necessarily to scale and that details not necessary for an understanding of the invention or that render other details difficult to perceive may be omitted. It should be understood, of course, that the invention is not necessarily limited to the particular embodiments illustrated herein.
-
FIGS. 1A , B, and C depicts a cross-sectional schematic diagram of nanostructures comprising various shell-like structures enclosing a hollow internal void. -
FIG. 2A depicts the ring-like selected area electron diffraction pattern (“SAED”) pattern shown by the SnO2 in the nanostructured shell.FIG. 2B depicts the rutile tetragonal structure of SnO2.FIG. 2C is a magnified energy filtered Transmission electron microscope (“TEM”) image of a SnO2 nanosphere. -
FIG. 3 illustrates cross-sectional diagrams of the inside-out ripening mechanism that forms the basis of the one-pot template-free synthesis of a metal oxide hollow nanostructure. -
FIG. 4 illustrates the shell-by-shell template-based method of preparing a SnO2 nanosphere. -
FIG. 5 depicts cavity functionalization of a nanosphere with an Au nanoparticle. -
FIGS. 6A and 6B depict TEM images of Au/silica core/shell particles and double-shelled Au/SnO2 hollow colloids prepared via steps I and II ofFIG. 5 , respectively;FIG. 6C shows Au/SnO2 hollow colloids obtained by HF etching the colloids shown inFIG. 5B ;FIG. 6D depicts the EDX spectrum of the particles shown inFIG. 5 . -
FIG. 7A depicts a first cycle charge-discharge curve for SnO2 hollow nanospheres.FIG. 7B illustrates the comparative cycling performance of various nanostructures. -
FIG. 8 illustrates cyclic voltammograms of hollow SnO2 nanospheres (first and second cycle). The scan range of 0-1.5 V (vs. Lithium) was swept at the rate of 0.1 mV/s). - The hollow nanostructures of the present invention comprise one or more polycrystalline metal oxide nanostructured shells enclosing an inner cavity or “internal void.” As used herein, the terms cavity and void are interchangeable. Various metal oxides may be employed in the invention, including, but not restricted to oxides of titanium, zirconium, boron, aluminum, germanium, indium, gallium, hafnium, silicon, vanadium, tin, tantalum, iron, nickel, cobalt, zinc, copper and combinations thereof. In preferred embodiments, the metal oxides may be tin oxide (SnO2), titanium dioxide (TiO2), and zirconium oxide (ZrO2). More preferably, the metal oxide is SnO2.
- The hollow nanostructures as taught by the invention exhibit various configurations, including, but not limited to, nanoparticles, nanorod/belts/arrays, nanotube, nanodisks, nanoboxes, nanocylinders, nanospheres, nanococoons and nanospindles, among others. In one embodiment of the invention, the hollow nanostructures of the invention are symmetrical, in that they comprise at least one axis of symmetry; in other embodiments, the hollow nanostructures may be asymmetrical.
- As depicted in
FIGS. 1A , B, and C by way of example of a hollow nanosphere, the nanostructures of the invention comprise shell-like structures enclosing a hollow internal void. These nanostructures include, but are not limited to: -
- (i) a nanostructure comprising a single
nanostructured shell 300 enclosing a hollow internal void 304 (FIG. 1A ); - (ii) a nanostructure comprising a single
nanostructured shell 300 enclosing a hollowinternal void 304, in which is contained a solid or nanostructured inner core 306 (FIG. 1B ); - (iii) a multiple-shelled nanostructure comprising a single
nanostructured shell 300 and at least one additional concentricnanostructured shell 308 enclosing a hollowinternal void 304, which optionally comprises a solid or nanostructured inner core 306 (FIG. 1C ). As defined herein, the term “concentric” is not limited to circular shells, or shells that share a common center, but is meant to define shells that are “one inside the other.”
- (i) a nanostructure comprising a single
- In the embodiment in which the nanostructure comprises multiple nanostructured shells, the shells may be in direct contact with each other at one or more points on their respective surfaces, in full contact at all points on their respective adjacent surfaces, or may be separated by an intervening void. The intervening void may be completely hollow or may comprise an additional material. As stated above, the basic cross-sectional elements of the nanostructures as depicted are applicable to varying cross-sectional shapes, forms, and sizes.
- Typically, the average cross-sectional distance of the nanostructure, depending on its shape and morphology, may vary between about 50.0 nm to about 1,000.0 nm, more particularly between about 100.0 nm and about 700.00 nm, and still more particularly between about 200.0 nm and about 500.0 nm. The average thickness of the nanostructured shells may vary from about 10.0 nm and 50.0 nm, more particularly between about 15.0 nm and 40.0 nm, and still more particularly between about 20.0 nm and about 30.0 nm. In those embodiments of the nanostructures comprising an inner core, the core typically comprises an average diameter of between about 50.0 nm and 500.0 nm, more particularly between about 200.0 nm and about 400.0 nm, and still more particularly between about 75.0 nm and about 125.0 nm.
- In one embodiment, the nanostructures of the invention may comprise a single pore or a plurality of pores within one or more of the nanostructured shells. Unless stated herein, the pores may be present in any nanostructured shell anywhere on said shell. As discussed herein, the term pore may be construed as a hole of any shape or size across the entire thickness of a nanostructured shell. For those nanostructures comprising multiple nanostructured shells, the pores may be present in only one nanostructured shell, all nanostructured shells, or a subset of the nanostructured shells. In one embodiment of the invention, the pores are present in only the outermost shell. In another embodiment, the pores are present in every shell. In another embodiment, a pore in one nanostructured shell may be contiguous with a pore in an adjacent nanostructured shell. In yet another embodiment, a pore across each nanostructured shell is contiguous with a pore in the adjacent concentric shell such that the contiguous pores create an opening from the exterior of the nanostructure to the internal void.
- In keeping with IUPAC notation (J. Rouquerol et al., Pure & Appl. Chem., 66 (1994) 1739-1758), pores in the nanostructured shells may be macroporous pores with pore dimensions less than about 2.0 nm, macroporous with pore dimensions typically greater than about 50.0 nm, or mesoporous with pore dimensions between 2.0 and 50.0 nm. Typically, the pores in the nanostructured shells diameters between about 1.0 nm and about 10.0 nm, more particularly between about 3.0 nm and about 5.0 nm. In one embodiment, a single-shelled nanostructure may comprise a single macropore of sufficient diameter such that the resulting nanostructure resembles a cup or a bowl. In another embodiment, the presence of contiguous macropores in a multi-shelled nanostructure may result in a similar cup or bowl-like nanostructure. In yet another embodiment of the invention, the pores are formed by treating the nanostructure with a pore-forming material (porogen) followed by heating between 100 and 1,000° C. C. V. Nguyen et al., Chem. Mater. 11, 3080 (1999); C. Nguyen et al., Macromolecules 33, 4281 (2000). Heat may be applied at high temperatures in an autoclave. Alternately, the porogen-treated nanostructure may be dried at low temperatures (<0° C.) in a lyophilizer.
- The nanostructured shells of the invention are polycrystalline, typically comprising a plurality of tin oxide primary metal oxide “crystallites,” which may vary in size. The average size of these primary crystallites is between about 1.0 nm and about 50.0 nm, more particularly between about 10.0 nm and about 20.0 nm.
- X-ray diffraction patterns (“XRD”) conducted on a nanostructure comprising SnO2 nanostructured shells confirm the polycrystalline nature of the nanostructured shells. The XRD patterns determined can be assigned to tetragonal rutile SnO2 (cassiterite, JCPDS card No. 41-1445, space group: P42/mnm, ao=4.738 A, co=3.187 A) as is to be expected for polycrystalline SnO2. The SAED pattern shown in
FIG. 2A indicates that the nanostructures are polycrystalline and the diffraction rings from inside to outside can be indexed to (110), (101), (200), (211) and (112) planes of rutile SnO2, respectively. The diffraction rings come from different crystal planes, with each crystal plane in a primary crystal generating a point in the SAED pattern. The rutile tetragonal structure of SnO2 typically looks like the structure depicted inFIG. 2B , where the Sn atom is octahedrally surrounded by oxygen atoms, which, in turn, are surrounded by planar triangles of Sn atoms. - The cross-structural morphology of the metal oxide nanostructures of the invention are further illustrated by a low magnification transmission electron microscopy (“TEM”) image as shown in
FIG. 2C . The SnO2 nanospheres clearly depict the nanostructuredouter shell 300, theinner space 304 and aninternal core 306. The dark contrast inside each shell as shown inFIG. 2C reveals that the inner space is in fact filled with a solid core. Such nanostructures can be prepared using a template-free as well as the template-based methods taught by the invention and discussed herein. - As stated herein, controlled synthesis of the foregoing nanostructures may be carried out by a simple “one-pot” template-free manner or by using templates and employing a shell-by-shell deposition of the metal oxide. The one-pot template-free method based on a novel and unusual “inside-out Ostwald ripening mechanism” comprises the steps of combining metal oxide precursor with a solvent to create a mixture, optionally adding one or more yield-enhancing additives (fore example, urea-based additives) to this mixture, and heating this mixture for a predetermined reaction times. These steps may be followed by cooling, centrifugation and washing with deionized water. This one-pot, template-free method taught by the invention is highly advantageous over existing methods in that it involves fewer steps than existing methods suitable for high-yield mass production of mono-disperse, structurally sound metal oxide nanospheres. By way of example of the production of SnO2 nanospheres using a potassium stannate precursor, this template-free method has been shown to give high yield mass production of SnO2 hollow nanospheres as measured by the % of Sn units in the stannate precursor converted to SnO2 crystallites in the end-product, and at nearly 100% morphological yield (i.e., the percentage of nanospheres displaying the same size, shape and cross-sectional characteristics).
- Preferably, the precursor salt of the metal oxide is an alkali metal precursor salt, more preferably the alkali metal precursor salt is a sodium or a potassium salt, most preferably the potassium salt. Thus, when the desired metal oxide nanostructure is a SnO2 nanostructure, the metal precursor salts may be sodium stannate or potassium stannate. The mixed solvent typically comprises a polar solvent in water, preferably a highly polar solvent with some degree of hydrophobic/surfactant character, more preferably, any C2 to C10 alcohol which may be employed as a single component or in mixture with other additives. Typically, the yield-enhancing additives used in the method comprise urea compounds (such as urea and thiourea), —NH2 compounds (including, but not limited to ammonia, ethylenediamine, surfactants amines, diamines, ammonia, and hydrazine), or surfactants, both ionic and non-ionic (for example, cetyltrimethylammortium bromide (“CTAB”), Tween-based compounds, dodecyl sulfates, etc.). Preferably, yield-enhancing additives are urea-based catalytic additives such as urea and thiourea. Additional yield-enhancing additives, including ammonia, ethylenediamine and surfactants such as cetyltrimethylammortium bromide (“CTAB”) may be used during synthesis. In addition, ammonia may be used as a pH modifier. Ethylenediamine and the CTAB surfactant may be used to effect the shape and size of the end product. Typically, the mixture of the metal-oxide precursor in the mixed solvent and the yield enhancing additives is heated to a temperature of between 140 and 200° C., preferably between 3 and 24 hours
- By way of example, describing the formation of a hollow SnO2 nanosphere by heating a mixture of potassium stannate in a mixed ethanol/water solvent in the presence of urea, the mechanism for the template-free formation of hollow nanostructures may be described. During the first stage of reaction, solid nanospheres are formed by hydrolysis of the stannate. With prolonged hydrothermal treatment, these solid nanospheres are transformed by the “inside-out Ostwald ripening” or “core evacuation” of the formed solid nanosphere in which the metal oxide crystals inside the solid nanosphere are forced out of the solid nanosphere to create an internal void. Ostwald ripening, first described by Wilhelm Ostwald in 1896, is a well-known particle (crystal) growth mechanism, in which the growth of large particles occurs at the expense of small ones while trying to minimize the surface energy (because of the smaller surface to volume ratio in large particles). In the case of the nanostructures of the invention, inside-out Ostwald ripening is understood to be the process by which the metal oxide crystals in the interior of the nanostructures dissolve preferentially because of the crystallization of the metal oxides on the surface of the forming nanostructures, even as the more amorphous material within the interior of the nanostructure amorphous tend to dissolve. L. Archer, X. W. Lou, Adv. Mater. 2006 18, 2325-2329; H. G. Yang, H. C. Zeng, J. Phys. Chem. B 2004, 108, 3492; J. Li H. C. Zeng, Angew. Chem. 2005, 117, 4416.
- This inside-out ripening process may initiate at regions either just below the external surface of the solid nanosphere, or around the nanostructure center, depending on the reaction conditions. Core evacuation by either mechanism yields, respectively, hollow nanostructures or hollow nanostructures in which the internal void comprises a solid core. Since the solid nanospheres typically formed first are not typically single-crystalline but comprise many tin oxide primary crystallites, the tin oxide particles in the inner region are packed more loosely than those in the outer layer resulting in larger surface energies which can lead to the tendency to dissolve. Moreover, as the hollowing process is typically accompanied by crystallization of the particles, the primary particles in the outer surfaces are relatively easy to crystallize facilitated by surrounding solvent, and therefore less crystalline particles in the inner region are easy to dissolve.
-
FIG. 3A illustrates cross-sectional diagrams of the proposed inside-out ripening mechanism: inside-out evacuation can initiate from just below surface of theshell 300 to form nanostructure (i) in which the hollowinner void 304 is beginning to be formed; then evolve to form a nanostructure (ii) with a well-definedinner void 304 further comprising aninner core 306; and further to hollow nanostructure (iii). Alternately, inside-out ripening mechanism may start around the central region of the solid sphere and evolve to particle (iii) directly. - By carefully controlling certain key reaction parameter in the template-free method of the invention the shape, size, morphology, and yield of the resulting metal oxide nanostructure may be determined. These parameters include, but are not limited to, the type and concentration of the metal-oxide precursor, the properties of the polar solvent and the polarity of the resultant polar solvent/water mixture, the type and amount of yield-enhancing additives used, the temperature at which the mixing reaction is conducted, and the length of time for which this reaction is performed.
- In one embodiment of the invention, changes in precursor concentration affect both the morphology and size of the end-product. By way of example of the production of SnO2 nanospheres, it was determined that when the precursor concentration of potassium stannate was reduced from 8.4 mM to 4.7 mM, the product comprised discrete hollow nanospheres with diameters in the range of 50.0 nm to 200.0 nm and a shell thickness of 10.0 nm. In comparison, keeping all other reaction parameters the same, a higher precursor concentration (e.g. 22 mM) produced nanospheres comprising a core spaced apart from and surrounded by a shell at approximately the same thickness (10.0 nm), but with larger diameters, for example, between about 300.0 and about 400.0 nm as well as a highly defined inner core within the internal void.
- Apart from precursor concentration, solvent characteristics are also relevant in affecting control of the end product. As stated previously, the solvent is preferably a highly polar solvent with some degree of hydrophobic/surfactant character, more preferably, any C2 to C10 alcohol which may be employed as a single component or in mixture with other additives. Typically, the polar solvents are dissolved in water to create a mixed solvent Typically, the ratio of C2 to C10 alcohol to water used is 1:1, but ratios may range from 5:1 to 1:4 to produce similar results. By way of example of the hydrothermal template-free production of SnO2 nanospheres in a mixed ethanol (“EtOH”)/water solvent, it was shown that the r value (EtOH v/v % in the solvent of EtOH/H2O) or polarity of the mixed solvent is a parameter which has an effect on the resultant metal oxide nanostructures. Typically, the preferred r values are in the range of 30-50%. In general, well-defined hollow nanospheres are difficult to produce when r is lower than 30%. In order to synthesize well-defined, mono-dispersed, hollow SnO2 nanospheres at r values <30%, the precursor concentrations must be increased than what are required for higher r values. If the r value remains fixed at less than 30%, and often even at less than 40%, aggregated clumps of small SnO2 crystallites form, instead well-defined SnO2 microspheres. For example, while keeping the r value fixed at 37.5% while changing the precursor potassium stannate concentrations, the products comprise mixtures of single hollow nanospheres (100-250 nm) and aggregated nanospheres at a precursor concentration of 13.5 mM, well-defined hollow nanospheres (300-550 nm) at a precursor concentration of 16.5 mM, and bowl-like large hollow spheres (450-750 nm) at a precursor concentration 19.5 mM, respectively.
- In another embodiment, the effect of urea-based catalytic additives such as urea and thiourea was found to increase both the product yield (measured by the % of Sn units in the stannate precursor converted to SnO2 crystallites in the end-product) and morphological yield to nearly 100%. As an example, hollow SnO2 nanospheres produced in the presence of urea, keeping all other reaction parameters the same are well dispersed with good monodispersity (usually 80-200 nm in diameter and an average shell thickness of about 20 nm).
- In another embodiment of the invention, temperature of the reaction can be varied to affect changes in shape, size and morphology. By way of example, in the case of hollow SnO2 nanospheres, it was shown that product synthesized at 150° C. comprises monodispersed hollow nanospheres with sizes in the range of 350-460 nm, while those prepared at 180° C. assume a bowl-like shape at a similar size. In another embodiment of the invention by way of example of hollow SnO2 nanospheres, the hydrothermal reaction period was shown to affect the final product. While the size of the SnO2 nanospheres obtained in the presence of thiourea at different hydrothermal reaction times do not typically increase with longer reaction times, their shell thicknesses may decrease from ˜50 nm to ˜20 nm, illustrating the continuing evacuation of SnO2 nanospheres thus increasing the size of the inner void, while at the same time decreasing the thickness of the nanostructured shell. Other time-dependent experiments in which all other synthesis conditions except reaction times were kept identical, the size distribution of the nanospheres appeared largely unaltered, while the morphology changed. Specifically, the product comprised solid nanospheres after a reaction time of 6 hours, and hollow nanospheres when allowed to react for 24 hours.
- The present invention also teaches a novel template based shell-by-shell nanostructure synthesis. Unlike existing methods of preparing nanostructures, the shell by shell synthesis taught by the invention creates nearly mono-disperse, narrow-size distribution, hollow nanostructures.
- Unlike existing methods taught in the prior art where the templates are pre-treated, the method as taught by the invention requires no prior surface modification of the template resulting in both time and cost-savings over existing methods for producing nanostructures. In particular, the advantages of this method allow this method to be used in large-scale and industrial scale applications. The deposition protocol involves direct treatment of the template with the metal oxide precursor in the presence of a mixed solvent and a catalyst which creates a polycrystalline nanostructured metal oxide shell over the template. In one embodiment of the invention, the method may be used to create a single nanostructured shell, while in other embodiments, the deposition protocol is successively repeated to create two or more polycrystalline nanostructured shells such that each newly created shell surrounds the prior formed shell. The shell-by-shell deposition protocol as taught by the invention may be used on any suitable template including, but not restricted to, templates made of silica, latex, carbon, gels, micelles, or combinations thereof. The shell-by-shell deposition protocol may also be used on templates of any shape, including, but not restricted to, spherical, polyhedral, cylindrical templates as well as any other symmetrical or asymmetrical templates. It has also been shown that the shell-by-shell synthesis as taught by the invention can work on template sizes in which the size of the template as measured by its longest cross-sectional distance is between 50.0 to 1,000.0 nm, preferably between 150.0 to 500M nm, and more preferably between 200.0 to 300.0 nm.
- By way of example only, the shell-by-shell synthesis of the invention may be illustrated by the formation of polycrystalline SnO2 nanospheres as depicted in
FIG. 4 . The SnO2 precursor is first hydrothermally deposited on silica nanospheres to form a singlenanostructured shell 300 as shown inStep 1. This single nanostructured shell then serves as an interim nanotemplate for further deposition. This deposition step may be repeated to formdouble shells 308 as shown inStep 2. As formed, the double-shelled nanostructures still contain partially dissolvedsilica cores 306, the sizes of which may be controlled by “etching” (or dissolution) with dilute HF (typically about 1-2% wt %) to form either a hollowinner void 304 with aninternal core 306 comprising the unetched template material (Step 3), or proceed to form a completely hollow inner void 306 (Step 4). Double-shelled hollow nanostructures can also be formed in a single step by increasing the relative amount of silica template (Step 5). By increasing the extent of HF etching, the double-shelled hollow nanostructures can be transformed into a single shell hollow nanostructure (Step 6). Typically, the hydrothermal deposition of SnO2 is carried out under basic conditions at a pH between 9 and 12, more preferably between 10 and 11. - As with the one-pot template-free method described herein, preferably, the precursor salt of the metal oxide is an alkali metal precursor salt, more preferably the alkali metal precursor salt is a sodium or a potassium salt, most preferably the alkali metal precursor salt is a potassium salt. Thus, when the desired metal oxide nanostructure is a SnO2 nanostructure, the metal precursor salts may be sodium stannate or potassium stannate. The mixed solvent typically comprises a polar solvent in water, preferably a highly polar solvent with some degree of hydrophobic/surfactant character, more preferably, any C2 to C10 alcohol which may be employed as a single component or in mixture with other additives. Typically, the yield-enhancing additives used in the method comprise urea compounds (such as urea and thiourea), —NH2 compounds (including, but not limited to ammonia, ethylenediamine, surfactants amines, diamines, ammonia, and hydrazine), or surfactants, both ionic and non-ionic (for example, cetyltrimethylammortium bromide (“CTAB”), Tween-based compounds, dodecyl sulfates, etc.) Preferably, yield-enhancing additives are urea-based additives such as urea and thiourea. In addition, ammonia may also be used as a pH modifier. Ethylenediamine and the CTAB surfactant may be used to effect the shape and size of the end product. Typically, the mixture of the metal-oxide precursor and the template in the mixed solvent (and optionally the yield enhancing additive)s is heated in an autoclave to a temperature of between 100 and 1000° C., preferably between 120 and 200° C., most preferably between 140 and 180° C.
- Various parameters are known to affect the shell-by-shell synthesis of the metal oxide nanostructures. For instance, depending on the kind of metal oxide nanostructure desired, the synthesis was found to have an optimal precursor concentration. By way of example, using the production of SnO2 nanospheres, and keeping the precursor concentration at a concentration of 16 mM, it was determined that using silica template amounts of 100 to 160 mg, more preferably 120 to 140 mg result in single-shelled nanostructures. When the amount of silica template is reduced from 120 mg to 80 mg, some double-shelled nanostructural formation is observed, but only in the form of irregular SnO2 crystallites. Only when the amount of silica template is further reduced to between 30 and 50 mg, more preferably 40 to 45 mg, are well-formed double-shelled hollow nanostructures observed.
- The size of the inner cavity may be controlled by the extent of HF etching. For instance, for those double-shelled nanostructures bearing an internal silica core, continuous HF etching leads to the greater dissolution of the inner silica core and the simultaneous enlargening of the inner cavity, while also causing the dissolution of the nanostructured double-shell into a single shell. L. Archer, X. W. Lou, Small 2006 0000, 00, No. 0 1-5 (Manuscript available at www.small-journal.com).
- For those nanostructures with only one shell, the structural integrity of a single-shelled nanostructure may be enhanced either by the creation of one or more additional shells or by a post-synthesis annealing process carried out at temperatures between 400 to 600° C., more preferably between 500 and 550° C. Alternately, structural integrity may also be enhanced by increasing the deposition temperature from a range of about 140 to 160° C. to between 180 to 200° C.
- The present invention allows for the exploitation of the single or multi-shelled hollow nanostructures by functionalizing the inner cavity with potentially useful nanoparticles. In one embodiment of the invention, the inner cavities may be functionalized with magnetic nanoparticles by first coating the nanoparticle with the template material. Magnetic nanoparticles include, but are not limited to, nanoparticles comprising ferric oxides including, but not limited to, Fe2O3, Fe3O4, CoFe2O4, as well as other metal oxides like CO3O4, ZnO, CuO, Cu2O, or even metal sulfide semiconductors like CdS, ZnS, etc. Materials with other functional properties, including noble metals, like Au, Ag, Pt, Pd, etc., may also be enclosed within the inner space of the nanostructures of the invention. The template material may include any suitable material that may be coated onto said magnetic nanoparticle. Template materials include, but are not limited to, latex, silica, gels, carbon, or combinations thereof. Such functionalized nanostructures with magnetized functionalities may be used in applications such as targeted drug delivery, separation methods, biomedical imaging, and use in photovoltaic cells among others. In one preferred embodiment of the invention, SnO2 is deposited on an α-Fe2O3 nanosphere, nanococoon, or nanospindle by the shell-by-shell synthesis taught by the invention to form the corresponding uniform multi-shelled SnO2 nanostructure.
- In yet another embodiment of the invention, noble metals including, but not limited to Au, Ag, Pt, Pd, etc. are treated with a template material and then subjected to a metal oxide shell-by-shell nanostructure synthesis as taught by the invention to create a mixed metal/metal oxide nanostructure functionalized to serve a particular end use. In one preferred embodiment of the invention, the functional metal is gold, while the metal oxide is SnO2. Using the shell-by-shell synthesis of the invention, a mixed Au—SnO2 metal-semiconductor composite nanostructure is created that is suitable for use in applications such as sensors, catalysts, controlled release drug delivery systems and bioseparations. The process by which an Au nanoparticle is functionalized within a hollow SnO2 nanostructure is shown in
FIG. 5 .Step 1 involves the conformal coating ofAu nanoparticles 310 with uniform shells ofsilica 312. The as-obtained Au/silica nanoparticle are then used as the template for subsequent SnO2 deposition to form a SnO2 shell 300 in Step II.FIGS. 6A and 6B depict TEM images of Au/silica core/shell particles 400 and double-shelled Au/SnO2 hollow colloids 402 prepared via steps I and II ofFIG. 5 , respectively;FIG. 6C shows Au/SnO2 hollow colloids obtained by HF etching the colloids shown inFIG. 5B ;FIG. 6D depicts the energy dispersive X-ray (“EDX”) spectrum of the particles shown inFIG. 5B . - The polycrystalline metal oxide nanostructures of the invention generated by the methods taught herein, may also be coated with additional industrially useful materials. In one embodiment, the metal oxide nanostructures of the invention may serve as templates to be coated with materials bearing electrical conductivity properties, where optionally the metal oxide nanostructures bear electrical conductivity properties as well. In a preferred embodiment, the metal oxide nanostructures are SnO2 nanostructures that are coated with semiconductors including, but not limited to, propylenevinylidenefluoride (“PVDF”), hexafluoropropylenevinylidenefluoride semiconductor (“PVDF-HFP”), and carbon-black filled PVDF or PVDF-HFP. For those nanostructures used as semiconductors in new generation lithium batteries, the added presence of such conductors on the metal oxide nanostructures enhances cyclability by improving the contact between the nanostructure and the battery. L. Archer, X. W. Lou, Adv. Mater. 2006 18, 2325-2329; Xinlu Li, Feiyu Kang, and Wanci Shen, Electrochem. Solid-State Lett., 2006, 9, A126-A129.
- The metal oxide nanostructured materials of the present invention may be used in a variety of applications. For example, the materials may be utilized as nanoscale chemical reactors, catalysis and photocatalysts, photovoltaic devices and as the anode in lithium storage batteries.
- When used as anode materials in lithium ion batteries, nanostructured SnO2 made in accordance with the present invention exhibits enhanced electrochemical properties. One hindrance against use of Sn-based anode materials in lithium ion batteries is the large volume change exhibited by Sn-based particles, owing to particle shattering and agglomeration during charging/discharging processes which leads to poor cyclability. The hollow nanostructures of the invention mitigate this problem. SnO2 nanostructures of the present invention exhibit initial discharge capacities between about 1000.0 mAh/g and 1,300 mAh/g and more particularly between about and about 1,100 and 1,200 mAh/g and still more particularly greater than 1,100 mAh/′g. Additionally, the nanostructures may undergo between about 25 and 45 cycles and more particularly between about 30 and 40 cycles while still functioning effectively at a discharge capacity of at least 300 mAh/g. It is believed that the superior lithium storage capacity is associated with the unique structure of hollow nanospheres with porous shells formed during the inside-out evacuation process.
- The present invention is illustrated, but in no way limited by the following examples.
- Hollow SnO2 nanoparticles were prepared by a hydrothermal method in an ethanol/H2O mixed solvent. Potassium stannate trihydrate (K2SnO3; 3H2O, Aldrich, 99.9%) was added to 30 ml of ethanol/H2O mixture with an r value of 25-50%, to achieve potassium stannate concentrations of 4.7 mM-40 mM. After gentle shaking by hand for about 5 minutes, a slightly white translucent or clear solution (depending on values of r and c) was obtained, which was then transferred to a 40 mL Teflon-lined stainless steel autoclave. In certain experiments, urea, thiourea or ethyl diamine were also used as additives, typically with overall concentrations of about 0.1 mM. After heating in an electric oven at 150° C. for a period of 3-48 hours, the autoclave was gradually cooled down in air, or rapidly using tap water. The white product was harvested by centrifugation and washed with deionized water and ethanol before drying at 50° C. overnight.
- The electrochemical properties of the hollow SnO2 nanospheres were characterized at room temperature. For these measurements SnO2 nanospheres were used to form the negative electrode in rechargeable lithium-ion batteries. The working electrode comprised 80 wt % of the active material (hollow SnO2), 10 wt % of conductivity agent (carbon black, Super-P), and 10 wt % of binder (polyvinylidene difluoride, PVDF, Aldrich). Lithium foil was used as the counter and reference electrodes. The electrolyte was 1 M Li PF6, in a 50:50 w/w mixture of ethylene carbonate and diethyl carbonate. Cell assembly was carried out in a glove box with the concentrations of moisture and oxygen below 1 ppm. The room-temperature electrode activities were measured using a Maccor-Series-2000 battery tester (Maccor, Inc. Tulsa, Okla.). The cells were charged and discharged at a constant current of ˜0.2 C and the fixed voltage limits were between 2 V and 5 mV. Cyclic voltammetry was performed on an EG&G model 273 potentiostat/galvanostat (Princeton Applied Research, Oakridge, Tenn.) using the active anode as the working electrode and lithium as both the counter and reference electrodes.
FIG. 7A shows the first cycle charge-discharge curve of SnO2hollow nanospheres 500. It is apparent fromFIG. 7A that the SnO2 hollow nanospheres display a very large initial discharge capacity of about 1140 mAh/g. This value is more than 75% greater than that of pristine SnO2 nanoparticles which display an initial discharge capacity of about 645 mAh/g and also higher than, any other previously reported SnO2 based hollow structures.FIG. 7B compares the cycling performance of as-prepared SnO2 hollow nanospheres of the invention (curve a) 502 with pristine SnO2 hollow nanospheres synthesized in accordance with the methods outlined in J. Power Sources 2005, 144, 220 by Wang and Lee (curve c) 506 and previous SnO2 hollow nanospheres synthesized in accordance with the methods outlined in Y. Wang et al., Chem. Mater, 2006, 18, 1347 (curve b) 504, which were all tested under similar conditions. It is apparent from this figure that the cycling performance of the SnO2 hollow nanospheres of the present invention is superior. - Specifically, while all materials show some fall-off in performance over time, the capacity of the SnO2 hollow nanospheres of the invention is still comparable to the theoretical capacity of SnO2 after more than 30 cycles; and much higher than the theoretical capacity of graphite after more than 40 cycles.
- Cyclic voltammograms, shown at
FIG. 8 , are consistent with previously reported SnO2 anode materials, indicating the same mechanism for lithium storage, nanopores in the shells and the interior microcavities of hollow nanospheres should allow or at least facilitate storage of the extra amount of lithium. Specifically,FIG. 8 illustrates cyclic voltammograms of hollow SnO2 nanospheres (first and second cycle). The scan range of 0-1.5 V (vs. Lithium) was swept at the rate of 0.1 mV/s). - Monodisperse silica nanospheres with different sizes were prepared from the well known Stobers method. W. Stober, A. Fink, E. Bohn, J. Colloid Interface Sci. 1968, 26, 62-69. Polycrystalline SnO2 shells were facilely deposited on silica templates without any prior surface modification by a hydrothermal method. Depending on the amount of nanostructures desired, 40-120 mg silica nanospheres were first dispersed by ultrasonication in 30 ml of ethanol/water (37.5 vol % ethanol) mixed solvent. To this white suspension, urea (0.9 g or 0.5 M) and potassium stannate trihydrate (˜144 mg or 16 mM; K2SnO3.3H2O, Aldrich, 99.9%) were added. After shaking by hand for about 5 minutes until the salt dissolved, the suspension was transferred to a 40 ml Teflon-lined stainless-steel autoclave, which was then heated in an airflow electric oven at 150-190° C. for 36 hours. After the autoclave cooled down naturally, the white product was harvested by centrifugation and washed with deionized water. This hydrothermal SnO2 deposition can be repeated to form double and even triple shells. The silica core was etched in a dilute ethanol/water solution of HF (˜2%).
- The Au/silica core/shell particles were prepared as described in detail by Liu et al. S. H. Liu, M. Y. Han, Adv. Funct. Matter. 2005, 15, 961-967. After extensive washing with water, the as-obtained Au/silica core/shell particles (˜50 mg) were directly used without drying as the template for the same SnO2 deposition.
- α-Fe2O3 spindles were prepared by aging a solution of 0.02 M FeCl3 and 0.45 mM NaH2PO4 at 105° C. for 48 hours as described by Ozaki et al. M. Ozaki, S. Kratohvili, E. Matijevic, J. Colloid Interface Sci., 1984, 102, 146-151. For SiO2 coating, 63 mg α-Fe2O3 spindles were first dispersed by ultrasonication in a mixture consisting 650 mL of 2-propanol and 65 mL of deionized water, followed by 60 mL of ammonia (29.6%). Under magnetic stirring, 4 mL of tetraethylorthosilicate (“TEOS”) in 2-propanol (10% v/v) was added, followed by another 3.5 mL of TEOS after 2 hours. The reaction was then continued for 18 hours. The α-Fe2O3/SiO2 particles were harvested by centrifugation, and washed with ethanol and water several times before being vacuum-dried at room temperature. For hydrothermal SnO2 deposition, 118 mg α-Fe2O3/SiO2 particles were dispersed in 25 mL of ethanol/water (37.5 vol % ethanol) mixed solvent. To this suspension, urea (0.75 g) and potassium stannate trihydrate (113 mg; K2SnO3.3H2O, Aldrich (St. Louis, Mo.), 99.9%) were added. After shaking by hand for about 5 minutes until the salts dissolved, the suspension was transferred to a 40 mL Teflon-lined stainless-steel autoclave, which was then heated in an air flow electric oven at 170° C. for 36 hours. After the autoclave was allowed to cool down naturally, the particles were washed with ethanol/water once before the same hydrothermal deposition was repeated. For synthesis of porous double-shelled nanococoons, about 34 mg α-Fe2O3/SiO2 particles were used. After annealing the particles at 550-600° C. for 8 hours, the silica was dissolved in 1 M NaOH solution at 50° C. for about 2 days (alternately, the silica is dissolved by etching in a very diluted HF solution as SnO2 tends to partially dissolve in NaOH solution when exposed to NaOH for extended periods of time).
- The nanococoons were characterized with X-ray powder diffraction (“XRD”) using a Scintag PAD X-ray Powder Diffractometer (Scintag PAD X, Cu Kα, λ=1.5406 Å) (Scintag, Inc, Cupertino, Calif.), transmission electron microscopy (TEM/SAED) using a JEOL-1200EX transmission electron microscope (120 kV) (JEOL, Tokyo, Japan), ultra-high vacuum scanning transmission electron microscopy (UHV-STEM, 100 kV) (Fisons Instruments, Inc, San Carlos, Calif.) equipped with energy dispersive X-ray analysis (EDX), and field emission scanning electron microscopy (FE-SEM; LEO 1550) (Carl Zeiss, Oberkochen, Germany). Nitrogen adsorption and desorption isotherms were measured using the Micromeritics ASAP 2020 Accelerated Surface Area and Porosimetry analyzer (Micromeritics, Inc., Norcross, Ga.).
- Numerous references, including patents and various publications, are cited and discussed in the description of this invention. The citation and discussion of such references is provided merely to clarify the description of the present invention and is not an admission that any reference is prior art to the invention described herein. All references cited and discussed in this specification are incorporated herein by reference in their entirety.
- Variations, modifications and other implementations of what is described herein will occur to those of ordinary skill in the art without departing from the spirit and scope of the invention. While certain embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims.
Claims (76)
1. A nanostructure comprising at least one metal oxide nanostructured shell defining an inner void.
2. The nanostructure of claim 1 comprising at least two metal oxide nanostructured concentric shells, wherein the shells are not covalently linked to each other.
3. The nanostructure of claim 2 , comprising two metal oxide nanostructured shell concentric shells, wherein the shells are not covalently linked to each other.
4. The nanostructure of claim 1 further comprising a solid core within the inner void.
5. The nanostructure of claim 4 wherein, the solid core comprises materials selected from the group consisting of Au, Ag, Pt and Pd.
6. The nanostructure of claim 5 , wherein the solid core comprises materials with magnetic properties.
7. The nanostructures of claim 6 , wherein the materials with magnetic properties comprise Fe, Co or Ni.
8. The nanostructures of claim 7 , wherein the materials with magnetic properties comprise ferric oxides.
9. The nanostructures of claim 6 , wherein the materials with magnetic properties are selected from the group consisting of ZnO, CuO, and Cu2O.
10. The nanostructures of claim 6 , wherein the materials with magnetic properties comprise metal sulfide semiconductors.
11. The nanostructures of claim 1 , wherein at least one metal oxide nanostructured shell has one or more pores.
12. The nanostructures of claim 8 , wherein the pore is an opening.
13. The nanostructure of claim 1 , wherein the nanostructure is spherical, cylindrical or polyhedral.
14. The nanostructure of claim 1 , wherein the nanostructure is bowl-shaped.
15. The nanostructure of claim 1 , wherein the nanostructure is selected from the group consisting of nanoparticles, nanorods, nanobelts, nano-arrays, nanotubes, nanodisks, nanoboxes, nanospheres, nanocylinders, nanococoons, and nanospindles.
16. The nanostructure of claim 1 , wherein the metal oxide comprises a metal selected from the group consisting of titanium, zirconium, aluminum, tin, germanium, indium, gallium, hafnium, vanadium, tantalum, zinc, copper, iron, cobalt, nickel, chromium, and manganese.
17. The nanostructure of claim 16 , wherein the metal oxide is tin oxide.
18. The nanostructure of claim 1 , wherein the nanostructure is polycrystalline.
19. The polycrystalline nanostructure of claim 18 , wherein the average size of each crystal is between 1.0 and 50.0 nm.
20. The polycrystalline nanostructure of claim 19 , wherein the average size of each crystal is between 10.0 and 20.0 nm.
21. The nanostructure of claim 1 , wherein the maximum average cross-sectional distance of the nanostructure is between 50.0 and 1,000.0 nm.
22. The nanostructure of claim 21 , wherein the maximum average cross-sectional distance of the nanostructure is between 100.0 and 500.0 nm.
23. The nanostructure of claim 22 , wherein the maximum average cross-sectional distance of the nanostructure is between 75.0 and 150.0 nm.
24. The nanostructure of claim 1 , wherein the thickness of the nanostructured shell defining the inner space is between 5.0 and 50.0 nm.
25. The nanostructure of claim 24 , wherein the thickness of the nanostructured shell defining the inner space is between 10.0 and 40.0 nm.
26. The nanostructure of claim 25 , wherein the thickness of the nanostructured shell defining the inner space is between 20.0 and 30.0 nm.
27. The nanostructure of claim 4 , wherein the average diameter of the solid core within the inner space is between 5.0 and 500.0 nm.
28. The nanostructure of claim 27 , wherein the average diameter of the solid core within the inner space is between 30.0 and 300.0 nm.
29. The nanostructure of claim 28 , wherein the average diameter of the solid core within the inner space is between 50.0 and 150.0 nm.
30. The nanostructure of claim 11 , wherein the average diameter of the pores in one or more of the nanostructured shells is between 1.0 and 100.0 nm.
31. The nanostructure of claim 30 , wherein the average diameter of the pores in one or more of the nanostructured shells is between 3.0 and 30.0 nm.
32. The nanostructure of claim 1 , wherein the nanostructure is rutile tetragonal SnO2.
33. The nanostructure of claim 29 , wherein the corresponding ring-like selected-area electron diffraction pattern of the nanostructure reveals diffraction rings from inside to outside which are indexed to (110, (101), (200), (211), and (112) planes of rutile SnO2 respectively.
34. A process to produce the nanostructures of claim 1 , comprising: mixing a metal oxide precursor with a solvent, and optionally one or more yield enhancing additives to form a mixture; and heating said mixture for at least about 3 hours.
35. The process of claim 34 , wherein the nanostructure is selected from the group consisting of nanoparticles, nanorods, nanobelts, nano-arrays, nanotubes, nanodisks, nanoboxes, nanospheres, nanocylinders, nanococoons, and nano spindles.
36. The process of claim 34 , wherein the metal oxide precursor is a precursor of metal oxides selected from the group consisting of titanium, zirconium, aluminum, tin, germanium, indium, gallium, hafnium, vanadium, tantalum, zinc, copper, iron, cobalt, nickel, chromium, and manganese.
37. The process of claim 36 , wherein the metal oxide precursor is a precursor of tin oxide.
38. The process of claim 37 , wherein the precursor is an alkali metal precursor salt.
39. The process of claim 38 , wherein the alkali metal is potassium or sodium.
40. The process of claim 39 , wherein the alkali metal is potassium.
41. The process of claim 34 , wherein the solvent is a polar solvent.
42. The process of claim 41 , wherein the polar solvent is an alcohol and water mixture.
43. The process of claim 42 , wherein the alcohol is any C2 to C10 alcohol.
44. The process of claim 34 , wherein the solvent is a non-polar solvent seeded with a polar entity.
45. The process of claim 44 , wherein the polar entities are chosen from the group consisting of surfactants, polymers, charged oligomers and particulate materials.
46. The process of claim 34 , wherein the yield enhancing additives are selected from the group consisting of urea compounds and —NH2 compounds.
47. The process of claim 46 , wherein the urea compounds are chosen from the group consisting of biuret, thiourea, thiobiuret, alkyl substituted ureas, aryl substituted ureas, alkyl substituted thioureas, aryl substituted thioureas, alkylene ether ureas, arylene ether ureas, alkylene ether thioureas and arylene ether thioureas.
48. The process of claim 34 , wherein the mixture is heated at a temperature of between about 140° C. and about 200° C. for between about 3 to about 24 hours.
49. The process of claim 48 , further comprising the step of cooling the nanostructure formed after heating.
50. The process of claim 49 , further comprising the step of washing the cooled nanostructure.
51. The process of claim 34 , wherein the nanostructure is formed by inside-out Ostwald ripening.
52. The process of claim 34 , wherein the nanostructure formed has enhanced electrochemical properties when used as an anode material in lithium ion batteries.
53. The process of claim 34 , wherein the nanostructure formed has initial discharge capacities between about 1000.0 mAh/g and 1,300,0 mAh/g.
54. The process of claim 34 , wherein the nanostructure formed can undergo at least about 25 discharge cycles while still functioning effectively at a discharge capacity of at least 300.0 mAh/g.
55. The process of claim 34 , wherein the nanostructure formed can undergo between 25 and 50 cycles while still functioning effectively at a discharge capacity of at least 300.0 mAh/g.
56. The nanostructure of claim 1 , further comprising a magnetic core.
57. The nanostructure of claim 56 , wherein the magnetic core comprises a ferric-based material.
58. The nanostructure of claim 57 , wherein the ferric based material is a ferric oxide.
59. The nanostructure of claim 58 , wherein the ferric oxide is Fe3O4.
60. The nanostructure of claim 1 , further comprising a core having electrical properties.
61. The nanostructure of claim 1 , further comprising a core having semiconductor properties.
62. The nanostructure of claim 1 , further comprising a core bearing noble metals.
63. The nanostructure of claim 62 , wherein the noble metals are chosen from the group consisting of Au, Ag, Pt and Pd.
64. A process to manufacture the nanostructure of claim 60 , comprising: (a) coating a material capable of being magnetized with a silica-based material to form a particle in which said material is coated with the silica-based material; (b) coating the particle of step (a) with metal oxide such that the nanotemplate is surrounded by at least one metal oxide nanostructured shell; (c) heating the nanotemplate of step (b) at a temperature between 400 to 1000° C. to cause annealing; (d) suspending said annealed structure of step (c) in a solvent suitable to dissolve the silica-based material.
65. The process of claim 64 , wherein the silica based material is amorphous silicon dioxide.
66. The process of claim 64 , wherein the material capable of being magnetized is α-Fe2O3.
67. The process of claim 66 , wherein the process further comprises a step in which the α-Fe2O3 is magnetized by H2 reduction to Fe3O4.
68. The nanostructure of claim 60 , further comprising an outermost shell comprising a semiconductor material.
69. The nanostructure of claim 68 , wherein the semiconductor material comprises carbon black.
70. The nanostructure of claim 68 , wherein the semiconductor material comprises a propylenevinylidenefluoride compound.
71. The nanostructure of claim 11 , wherein the pores are formed by treatment with a poregen material followed by heating at a temperature between 100° C. to 1000° C.
72. The nanostructure of claim 11 , wherein the pores are formed by treatment with a poregen material followed by lyophilization at a temperature less than 0° C.
73. A process to produce the nanostructure of claim 1 , comprising: (a) hydrothermally depositing a metal oxide precursor on a template to form a nanostructure comprising a metal oxide nanostructured shell on said template; and (b) treating the nanostructure of step (a) with a solvent to dissolve the template material to create an internal void in said nanostructure.
74. A process to produce the nanostructure of claim 2 , comprising: (a) hydrothermally depositing a metal oxide precursor at least two times on a template to form a nanostructure comprising a plurality of metal oxide nanostructured shells on said template; and (b) treating the nanostructure of step (a) with a solvent to dissolve the template material to create an internal void in said nanostructure.
75. The process of claim 73 , wherein the metal oxide is SnO2.
76. The process of claim 73 , wherein the template is a silica-based compound.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/303,668 US20100258759A1 (en) | 2006-06-06 | 2007-06-06 | Nanostructured Metal Oxides Comprising Internal Voids and Methods of Use Thereof |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US80403106P | 2006-06-06 | 2006-06-06 | |
PCT/US2007/070553 WO2008048716A2 (en) | 2006-06-06 | 2007-06-06 | Nanostructured metal oxides comprising internal voids and methods of use thereof |
US12/303,668 US20100258759A1 (en) | 2006-06-06 | 2007-06-06 | Nanostructured Metal Oxides Comprising Internal Voids and Methods of Use Thereof |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2007/070553 A-371-Of-International WO2008048716A2 (en) | 2006-06-06 | 2007-06-06 | Nanostructured metal oxides comprising internal voids and methods of use thereof |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/721,440 Continuation US8945504B2 (en) | 2006-06-06 | 2012-12-20 | Nanostructured metal oxides comprising internal voids and methods of use thereof |
Publications (1)
Publication Number | Publication Date |
---|---|
US20100258759A1 true US20100258759A1 (en) | 2010-10-14 |
Family
ID=39314702
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/303,668 Abandoned US20100258759A1 (en) | 2006-06-06 | 2007-06-06 | Nanostructured Metal Oxides Comprising Internal Voids and Methods of Use Thereof |
US13/721,440 Expired - Fee Related US8945504B2 (en) | 2006-06-06 | 2012-12-20 | Nanostructured metal oxides comprising internal voids and methods of use thereof |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/721,440 Expired - Fee Related US8945504B2 (en) | 2006-06-06 | 2012-12-20 | Nanostructured metal oxides comprising internal voids and methods of use thereof |
Country Status (4)
Country | Link |
---|---|
US (2) | US20100258759A1 (en) |
EP (1) | EP2038899A4 (en) |
CN (1) | CN101501790A (en) |
WO (1) | WO2008048716A2 (en) |
Cited By (38)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100054988A1 (en) * | 2008-08-29 | 2010-03-04 | Kwangyeol Lee | Photocatalytic nanocapsule and fiber for water treatment |
US20100056366A1 (en) * | 2008-08-27 | 2010-03-04 | Korea University Industrial & Academic Collaboration Foundation | Nanoparticles including metal oxide having catalytic activity |
US20110174368A1 (en) * | 2007-12-10 | 2011-07-21 | Lee Sang-Soo | Composite electrolyte and the preparation method thereof, and dye-sensitized solar cell using the same |
CN102275981A (en) * | 2011-07-15 | 2011-12-14 | 东华大学 | Preparation method of self-substrate SnO2 nanorod array |
US20120132644A1 (en) * | 2009-03-16 | 2012-05-31 | Zhiyong Gu | Methods for the fabrication of nanostructures heating elements |
WO2012106102A1 (en) * | 2011-02-01 | 2012-08-09 | Toyota Motor Engineering & Manufacturing North America, Inc. | Electrode material with core-shell structure |
CN102773085A (en) * | 2012-06-27 | 2012-11-14 | 天津大学 | Facilitated transport type TiO2/void/SiO2 photocatalysis particle and preparation method thereof |
KR101308953B1 (en) | 2010-12-30 | 2013-09-24 | 한국조폐공사 | Magnetic Particle and the Fabrication Method Thereof |
WO2013169079A1 (en) * | 2012-05-11 | 2013-11-14 | 주식회사 엘지화학 | Hollow metal nanoparticles |
KR101347664B1 (en) * | 2010-12-30 | 2014-01-10 | 한국조폐공사 | Magnetic Particle and the Fabrication Method Thereof |
WO2014104805A1 (en) * | 2012-12-27 | 2014-07-03 | 주식회사 엘지화학 | Hollow metal nanoparticle supported by support body |
WO2014104806A1 (en) * | 2012-12-27 | 2014-07-03 | 주식회사 엘지화학 | Method for manufacturing hollow metal nanoparticle supported by support body |
CN103979613A (en) * | 2014-05-23 | 2014-08-13 | 苏州大学 | Method for preparing ferroferric oxide nanorod |
US20140272447A1 (en) * | 2013-03-13 | 2014-09-18 | Syracuse University | Method to control void formation in nanomaterials using core/alloy nanoparticles with stainless interfaces |
US20140322601A1 (en) * | 2012-11-30 | 2014-10-30 | Lg Chem, Ltd. | Anode active material for lithium secondary battery and lithum secondary battery comprising the same |
CN104192889A (en) * | 2014-08-04 | 2014-12-10 | 上海交通大学 | Method for preparing monodisperse cuprous oxide hollow sphere |
WO2014196806A1 (en) * | 2013-06-07 | 2014-12-11 | 주식회사 엘지화학 | Metal nanoparticles |
WO2014196785A1 (en) * | 2013-06-07 | 2014-12-11 | 주식회사 엘지화학 | Hollow metal nanoparticles |
CN104483351A (en) * | 2014-11-27 | 2015-04-01 | 武汉工程大学 | Palladium-doped hollow porous stannic oxide microcubes as well as preparation method and application thereof |
CN104528810A (en) * | 2015-01-20 | 2015-04-22 | 天津大学 | Preparation method for preparing stannic oxide nanorod cluster by using one-step hydrothermal method |
WO2015065120A1 (en) * | 2013-11-01 | 2015-05-07 | 주식회사 엘지화학 | Fuel cell and method for manufacturing same |
WO2015080497A1 (en) * | 2013-11-29 | 2015-06-04 | 주식회사 엘지화학 | Fuel cell and method of manufacturing same |
US9093205B2 (en) | 2013-05-23 | 2015-07-28 | Toyota Motor Engineering & Manufacturing North America, Inc. | Superparamagnetic iron oxide and silica nanoparticles of high magnetic saturation and a magnetic core containing the nanoparticles |
KR101560988B1 (en) | 2013-11-08 | 2015-10-15 | 주식회사 엘지화학 | Fuel cell and methode for manufacturing the same |
US20150303449A1 (en) * | 2014-04-17 | 2015-10-22 | Korea Advanced Institute Of Science And Technology | Method for manufacturing of metal oxide nanoparticles and metal oxide nanoparticles thereby |
CN105307798A (en) * | 2013-06-07 | 2016-02-03 | Lg化学株式会社 | Metal nanoparticles |
CN105293571A (en) * | 2015-11-30 | 2016-02-03 | 天津工业大学 | Method for directly preparing stannic oxide nano-particles by using metallic tin |
US9340461B1 (en) | 2014-11-24 | 2016-05-17 | Ut-Battelle, Llc | Method of making controlled morphology metal-oxides |
US20170194651A1 (en) * | 2015-12-30 | 2017-07-06 | Robert Bosch Gmbh | Metal oxide cathode |
US20180230611A1 (en) * | 2017-02-16 | 2018-08-16 | Honda Motor Co., Ltd. | Method for producing core shell nanoparticles |
US10056618B2 (en) | 2011-09-12 | 2018-08-21 | The Board Of Trustees Of The Leland Stanford Junior University | Encapsulated sulfur cathodes for rechargeable lithium batteries |
US10112172B2 (en) * | 2014-10-17 | 2018-10-30 | Korea Institute Of Energy Research | Egg-shell type hybrid structure of highly dispersed nanoparticle-metal oxide support, preparation method thereof, and use thereof |
CN110142049A (en) * | 2019-05-15 | 2019-08-20 | 广州大学 | A kind of cadmium sulfide and zinc sulphide nucleocapsid structure catalysis material preparation method for hydrogen manufacturing |
US10456838B2 (en) | 2014-08-14 | 2019-10-29 | Lg Chem, Ltd. | Method for producing metal nanoparticles |
US10883955B2 (en) * | 2013-03-21 | 2021-01-05 | Cornell University | Carbon material supported hollow metal oxide nanoparticles, methods and applications |
US10910153B2 (en) | 2013-07-15 | 2021-02-02 | Toyota Motor Engineering & Manufacturing North America, Inc. | Superparamagnetic iron cobalt alloy and silica nanoparticles of high magnetic saturation and a magnetic core containing the nanoparticles |
US10984933B2 (en) | 2013-06-19 | 2021-04-20 | Toyota Motor Engineering & Manufacturing North America, Inc. | Superparamagnetic iron cobalt ternary alloy and silica nanoparticles of high magnetic saturation and a magnetic core containing the nanoparticles |
CN114162851A (en) * | 2020-09-10 | 2022-03-11 | 中国民航大学 | Nano flower-like SnO2One-step template-free hydrothermal preparation method of gas-sensitive material |
Families Citing this family (30)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100055170A1 (en) * | 2008-08-26 | 2010-03-04 | Korea University Industrial & Academic Collaboration Foundation | Metal core nanocapsules |
CN102282704A (en) * | 2008-11-18 | 2011-12-14 | 康奈尔大学 | Carbon coated anode materials |
DE102008060259A1 (en) * | 2008-12-03 | 2010-06-10 | Bayer Technology Services Gmbh | Catalyst for oxidation reactions in the presence of hydrogen chloride and / or chlorine and process for its preparation, and its use |
JP2010208875A (en) * | 2009-03-09 | 2010-09-24 | Tokyo Institute Of Technology | Magnetic hollow particle and method for producing the same |
US20130105397A1 (en) * | 2010-01-12 | 2013-05-02 | Council Of Scientific & Industrial Research | Magnetic dye-adsorbent catalyst |
CN101785983B (en) * | 2010-04-08 | 2012-04-04 | 哈尔滨工业大学 | Method for preparing carbon hollow sphere composite material carrying tin oxide |
CN101847714B (en) * | 2010-05-20 | 2012-10-17 | 复旦大学 | Method for preparing carbon-coated core-shell structure nanometer alloy material of cathode for lithium-ion battery |
US20120094192A1 (en) * | 2010-10-14 | 2012-04-19 | Ut-Battelle, Llc | Composite nanowire compositions and methods of synthesis |
CN102468026A (en) * | 2010-11-04 | 2012-05-23 | 孙文夫 | Giant magnetic, rectangular magnetic, hard magnetic, hollow and other series bubbles and manufacturing method thereof |
JP5784961B2 (en) * | 2011-04-28 | 2015-09-24 | 国立大学法人高知大学 | Method for producing coated active material |
CN103035907B (en) * | 2012-12-08 | 2015-08-05 | 浙江工业大学 | A kind of coated hollow tri-iron tetroxide of carbon and application thereof |
CN103215037A (en) * | 2013-03-29 | 2013-07-24 | 长春理工大学 | Method for synthesizing upconversion fluorescence hollow nanosphere based on sodium polyacrylate microsphere template synthesis |
DE102013014627A1 (en) * | 2013-08-30 | 2015-03-05 | Volkswagen Aktiengesellschaft | Pre-lithiation of silicon particles |
US9272268B2 (en) * | 2014-04-01 | 2016-03-01 | Ut-Battelle, Llc | Catalysts for low temperature oxidation |
CN104209513B (en) * | 2014-09-04 | 2017-02-22 | 东南大学 | Superparamagnetic nanometer composite material and preparation method for same |
CN105481004B (en) * | 2014-09-17 | 2017-07-14 | 中国科学院上海硅酸盐研究所 | A kind of high electric property tin dioxide nanometer tube and preparation method thereof |
CN104300136B (en) * | 2014-10-17 | 2017-01-11 | 武汉理工大学 | One-dimensional manganese oxide/carbon coaxial hollow nanorod as well as preparation method and application of nanorod |
US11251420B2 (en) | 2016-12-15 | 2022-02-15 | Honda Motor Co., Ltd. | Composite electrode materials for fluoride-ion electrochemical cells |
US11177512B2 (en) | 2016-12-15 | 2021-11-16 | Honda Motor Co., Ltd. | Barium-doped composite electrode materials for fluoride-ion electrochemical cells |
US11581582B2 (en) | 2015-08-04 | 2023-02-14 | Honda Motor Co., Ltd. | Liquid-type room-temperature fluoride ion batteries |
US11749797B2 (en) | 2016-12-15 | 2023-09-05 | Honda Motor Co., Ltd. | Nanostructural designs for electrode materials of fluoride ion batteries |
KR101795146B1 (en) | 2015-09-16 | 2017-11-07 | 현대자동차주식회사 | A nanotubular intermetallic compound catalyst for cathode of lithium-air battery and a method of producing the same |
DE112019002675T5 (en) * | 2018-05-25 | 2021-05-06 | California Institute Of Technology | BARIUM DOPED COMPOSITE ELECTRODE MATERIALS FOR FLUORIDION ELECTROCHEMICAL CELLS |
US11228026B2 (en) * | 2018-06-20 | 2022-01-18 | Honda Motor Co., Ltd. | Two phase shell formation on metal nanostructures |
CN113562690B (en) * | 2020-04-28 | 2022-05-31 | 清华大学 | Nano manipulator |
CN111960932B (en) * | 2020-09-16 | 2022-11-08 | 沈阳药科大学 | Dichlororesorcinol compound and preparation method and medical application thereof |
CN113113604B (en) * | 2021-03-04 | 2022-08-05 | 华南师范大学 | Micron open-cell cage-shaped defect MnO @ Ni material and preparation method and application thereof |
CN113200530B (en) * | 2021-05-19 | 2022-04-22 | 江苏中兴派能电池有限公司 | Preparation method of carbon-coated nickel phosphide composite negative electrode material |
CN113674942B (en) * | 2021-08-25 | 2022-02-22 | 广东泛瑞新材料有限公司 | Wide-temperature-range high-frequency magnetic material and preparation method and application thereof |
CN114920298B (en) * | 2022-05-20 | 2023-06-23 | 郑州轻工业大学 | Crystalline two-dimensional porous CuO/WO 3 Nanosheets, preparation method thereof and application of nanosheets as acetoin sensor |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030067003A1 (en) * | 2001-09-28 | 2003-04-10 | Gole James L. | Tin oxide nanostructures |
US20030082237A1 (en) * | 2001-10-02 | 2003-05-01 | Jennifer Cha | Nanoparticle assembled hollow spheres |
US20030153001A1 (en) * | 1997-10-14 | 2003-08-14 | Alnis, Llc | Molecular compounds having complementary surfaces to targets |
US20040126659A1 (en) * | 2002-09-10 | 2004-07-01 | Graetz Jason A. | High-capacity nanostructured silicon and lithium alloys thereof |
US20050090634A1 (en) * | 1998-12-18 | 2005-04-28 | Morse Daniel E. | Methods, compositions, and biomimetic catalysts for the synthesis of silica, polysilsequioxanes, polysiloxanes, non-silicon metalloid-oxygen networks, polymetallo-oxanes, and their organic or hydrido conjugates and derivatives |
US20050281884A1 (en) * | 2004-06-01 | 2005-12-22 | The Penn State Research Foundation | Unagglomerated core/shell nanocomposite particles |
US20060045831A1 (en) * | 2004-08-30 | 2006-03-02 | Fernando Galembeck | Aluminum phosphate or polyphosphate particles for use as pigments in paints and method of making same |
US20060054506A1 (en) * | 1999-10-06 | 2006-03-16 | Natan Michael J | Surface enhanced spectrometry-active composite nanoparticles |
US20060102871A1 (en) * | 2003-04-08 | 2006-05-18 | Xingwu Wang | Novel composition |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH07237923A (en) * | 1994-01-07 | 1995-09-12 | Japan Synthetic Rubber Co Ltd | Hollow particle containing ferrite |
US6004525A (en) * | 1997-10-06 | 1999-12-21 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Hollow oxide particle and process for producing the same |
JP4096330B2 (en) * | 2002-02-27 | 2008-06-04 | 独立行政法人科学技術振興機構 | Core / shell structure having controlled voids inside, structure using it as a constituent element, and method for preparing them |
AU2003209238A1 (en) * | 2002-04-09 | 2003-10-27 | The Government Of The United States Of America As Represented By The Secretary Of The Navy | Magnetic nanoparticles having passivated metallic cores |
-
2007
- 2007-06-06 CN CNA2007800291344A patent/CN101501790A/en active Pending
- 2007-06-06 WO PCT/US2007/070553 patent/WO2008048716A2/en active Application Filing
- 2007-06-06 US US12/303,668 patent/US20100258759A1/en not_active Abandoned
- 2007-06-06 EP EP07863352.6A patent/EP2038899A4/en not_active Withdrawn
-
2012
- 2012-12-20 US US13/721,440 patent/US8945504B2/en not_active Expired - Fee Related
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030153001A1 (en) * | 1997-10-14 | 2003-08-14 | Alnis, Llc | Molecular compounds having complementary surfaces to targets |
US20050090634A1 (en) * | 1998-12-18 | 2005-04-28 | Morse Daniel E. | Methods, compositions, and biomimetic catalysts for the synthesis of silica, polysilsequioxanes, polysiloxanes, non-silicon metalloid-oxygen networks, polymetallo-oxanes, and their organic or hydrido conjugates and derivatives |
US20060054506A1 (en) * | 1999-10-06 | 2006-03-16 | Natan Michael J | Surface enhanced spectrometry-active composite nanoparticles |
US20030067003A1 (en) * | 2001-09-28 | 2003-04-10 | Gole James L. | Tin oxide nanostructures |
US20030082237A1 (en) * | 2001-10-02 | 2003-05-01 | Jennifer Cha | Nanoparticle assembled hollow spheres |
US20040126659A1 (en) * | 2002-09-10 | 2004-07-01 | Graetz Jason A. | High-capacity nanostructured silicon and lithium alloys thereof |
US20060102871A1 (en) * | 2003-04-08 | 2006-05-18 | Xingwu Wang | Novel composition |
US20050281884A1 (en) * | 2004-06-01 | 2005-12-22 | The Penn State Research Foundation | Unagglomerated core/shell nanocomposite particles |
US20060045831A1 (en) * | 2004-08-30 | 2006-03-02 | Fernando Galembeck | Aluminum phosphate or polyphosphate particles for use as pigments in paints and method of making same |
Cited By (68)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110174368A1 (en) * | 2007-12-10 | 2011-07-21 | Lee Sang-Soo | Composite electrolyte and the preparation method thereof, and dye-sensitized solar cell using the same |
US20160111715A9 (en) * | 2008-06-20 | 2016-04-21 | Toyota Motor Engineering & Manufacturing North America, Inc. | Electrode material with core-shell structure |
US20100056366A1 (en) * | 2008-08-27 | 2010-03-04 | Korea University Industrial & Academic Collaboration Foundation | Nanoparticles including metal oxide having catalytic activity |
US8216961B2 (en) * | 2008-08-27 | 2012-07-10 | Korea University Research And Business Foundation | Nanoparticles including metal oxide having catalytic activity |
US8415267B2 (en) | 2008-08-27 | 2013-04-09 | Korea University Research And Business Foundation | Nanoparticles including metal oxide having catalytic activity |
US20100054988A1 (en) * | 2008-08-29 | 2010-03-04 | Kwangyeol Lee | Photocatalytic nanocapsule and fiber for water treatment |
US20120132644A1 (en) * | 2009-03-16 | 2012-05-31 | Zhiyong Gu | Methods for the fabrication of nanostructures heating elements |
KR101308953B1 (en) | 2010-12-30 | 2013-09-24 | 한국조폐공사 | Magnetic Particle and the Fabrication Method Thereof |
KR101347664B1 (en) * | 2010-12-30 | 2014-01-10 | 한국조폐공사 | Magnetic Particle and the Fabrication Method Thereof |
WO2012106102A1 (en) * | 2011-02-01 | 2012-08-09 | Toyota Motor Engineering & Manufacturing North America, Inc. | Electrode material with core-shell structure |
CN102275981A (en) * | 2011-07-15 | 2011-12-14 | 东华大学 | Preparation method of self-substrate SnO2 nanorod array |
CN102275981B (en) * | 2011-07-15 | 2013-05-08 | 东华大学 | Preparation method of self-substrate SnO2 nanorod array |
US10056618B2 (en) | 2011-09-12 | 2018-08-21 | The Board Of Trustees Of The Leland Stanford Junior University | Encapsulated sulfur cathodes for rechargeable lithium batteries |
US11189836B2 (en) | 2011-09-12 | 2021-11-30 | The Board Of Trustees Of The Leland Stanford Junior University | Encapsulated sulfur cathodes for rechargeable lithium batteries |
US10566630B2 (en) | 2011-09-12 | 2020-02-18 | The Board Of Trustees Of The Leland Stanford Junior University | Encapsulated sulfur cathodes for rechargeable lithium batteries |
WO2013169079A1 (en) * | 2012-05-11 | 2013-11-14 | 주식회사 엘지화학 | Hollow metal nanoparticles |
US9776247B2 (en) | 2012-05-11 | 2017-10-03 | Lg Chem, Ltd. | Hollow metal nano particles |
CN102773085A (en) * | 2012-06-27 | 2012-11-14 | 天津大学 | Facilitated transport type TiO2/void/SiO2 photocatalysis particle and preparation method thereof |
CN104396063A (en) * | 2012-11-30 | 2015-03-04 | 株式会社Lg化学 | Anode active material for lithium secondary battery and lithium secondary battery including same |
US10276864B2 (en) * | 2012-11-30 | 2019-04-30 | Lg Chem, Ltd. | Anode active material for lithium secondary battery and lithium secondary battery comprising the same |
US20140322601A1 (en) * | 2012-11-30 | 2014-10-30 | Lg Chem, Ltd. | Anode active material for lithium secondary battery and lithum secondary battery comprising the same |
JP2016504187A (en) * | 2012-12-27 | 2016-02-12 | エルジー・ケム・リミテッド | Method for producing a catalyst comprising hollow metal nanoparticles supported on a support |
WO2014104806A1 (en) * | 2012-12-27 | 2014-07-03 | 주식회사 엘지화학 | Method for manufacturing hollow metal nanoparticle supported by support body |
US9517460B2 (en) | 2012-12-27 | 2016-12-13 | Lg Chem, Ltd. | Method for fabricating hollow metal nano particles supported on carrier |
WO2014104805A1 (en) * | 2012-12-27 | 2014-07-03 | 주식회사 엘지화학 | Hollow metal nanoparticle supported by support body |
US9517450B2 (en) | 2012-12-27 | 2016-12-13 | Lg Chem, Ltd. | Hollow metal nano particles supported on carrier |
US20140272447A1 (en) * | 2013-03-13 | 2014-09-18 | Syracuse University | Method to control void formation in nanomaterials using core/alloy nanoparticles with stainless interfaces |
US10695831B2 (en) * | 2013-03-13 | 2020-06-30 | Syracuse University | Method to control void formation in nanomaterials using core/alloy nanoparticles with stainless interfaces |
US9604281B2 (en) * | 2013-03-13 | 2017-03-28 | Syracuse University | Method to control void formation in nanomaterials using core/alloy nanoparticles with stainless interfaces |
US20170165749A1 (en) * | 2013-03-13 | 2017-06-15 | Syracuse University | Method to control void formation in nanomaterials using core/alloy nanoparticles with stainless interfaces |
US10883955B2 (en) * | 2013-03-21 | 2021-01-05 | Cornell University | Carbon material supported hollow metal oxide nanoparticles, methods and applications |
US9093205B2 (en) | 2013-05-23 | 2015-07-28 | Toyota Motor Engineering & Manufacturing North America, Inc. | Superparamagnetic iron oxide and silica nanoparticles of high magnetic saturation and a magnetic core containing the nanoparticles |
KR20160091303A (en) * | 2013-06-07 | 2016-08-02 | 주식회사 엘지화학 | Metal nano particles |
US9776173B2 (en) | 2013-06-07 | 2017-10-03 | Lg Chem, Ltd. | Hollow metal nanoparticles |
WO2014196806A1 (en) * | 2013-06-07 | 2014-12-11 | 주식회사 엘지화학 | Metal nanoparticles |
US10350678B2 (en) | 2013-06-07 | 2019-07-16 | Lg Chem, Ltd. | Metal nanoparticles |
KR101858304B1 (en) * | 2013-06-07 | 2018-05-16 | 주식회사 엘지화학 | Hollow metal nano particles |
KR101649029B1 (en) | 2013-06-07 | 2016-08-17 | 주식회사 엘지화학 | Metal nano particles |
WO2014196785A1 (en) * | 2013-06-07 | 2014-12-11 | 주식회사 엘지화학 | Hollow metal nanoparticles |
CN105307798A (en) * | 2013-06-07 | 2016-02-03 | Lg化学株式会社 | Metal nanoparticles |
KR101705489B1 (en) | 2013-06-07 | 2017-02-09 | 주식회사 엘지화학 | Metal nano particles |
US10322452B2 (en) | 2013-06-07 | 2019-06-18 | Lg Chem, Ltd. | Metal nanoparticles |
KR20140143719A (en) * | 2013-06-07 | 2014-12-17 | 주식회사 엘지화학 | Metal nano particles |
US10984933B2 (en) | 2013-06-19 | 2021-04-20 | Toyota Motor Engineering & Manufacturing North America, Inc. | Superparamagnetic iron cobalt ternary alloy and silica nanoparticles of high magnetic saturation and a magnetic core containing the nanoparticles |
US10910153B2 (en) | 2013-07-15 | 2021-02-02 | Toyota Motor Engineering & Manufacturing North America, Inc. | Superparamagnetic iron cobalt alloy and silica nanoparticles of high magnetic saturation and a magnetic core containing the nanoparticles |
US9614227B2 (en) | 2013-11-01 | 2017-04-04 | Lg Chem, Ltd. | Fuel cell and method of manufacturing same |
WO2015065120A1 (en) * | 2013-11-01 | 2015-05-07 | 주식회사 엘지화학 | Fuel cell and method for manufacturing same |
KR101560988B1 (en) | 2013-11-08 | 2015-10-15 | 주식회사 엘지화학 | Fuel cell and methode for manufacturing the same |
WO2015080497A1 (en) * | 2013-11-29 | 2015-06-04 | 주식회사 엘지화학 | Fuel cell and method of manufacturing same |
US10483553B2 (en) | 2013-11-29 | 2019-11-19 | Lg Chem, Ltd. | Fuel cell including a carrier-metal nanoparticle complex and method of manufacturing same |
US10193133B2 (en) * | 2014-04-17 | 2019-01-29 | Korea Advanced Institute Of Science And Technlogy | Method for manufacturing of metal oxide nanoparticles and metal oxide nanoparticles thereby |
US20150303449A1 (en) * | 2014-04-17 | 2015-10-22 | Korea Advanced Institute Of Science And Technology | Method for manufacturing of metal oxide nanoparticles and metal oxide nanoparticles thereby |
CN103979613A (en) * | 2014-05-23 | 2014-08-13 | 苏州大学 | Method for preparing ferroferric oxide nanorod |
CN104192889A (en) * | 2014-08-04 | 2014-12-10 | 上海交通大学 | Method for preparing monodisperse cuprous oxide hollow sphere |
US10456838B2 (en) | 2014-08-14 | 2019-10-29 | Lg Chem, Ltd. | Method for producing metal nanoparticles |
US10112172B2 (en) * | 2014-10-17 | 2018-10-30 | Korea Institute Of Energy Research | Egg-shell type hybrid structure of highly dispersed nanoparticle-metal oxide support, preparation method thereof, and use thereof |
US9340461B1 (en) | 2014-11-24 | 2016-05-17 | Ut-Battelle, Llc | Method of making controlled morphology metal-oxides |
WO2016085734A1 (en) * | 2014-11-24 | 2016-06-02 | Ut-Battelle, Llc | Method of making controlled morphology metal oxides |
CN104483351A (en) * | 2014-11-27 | 2015-04-01 | 武汉工程大学 | Palladium-doped hollow porous stannic oxide microcubes as well as preparation method and application thereof |
CN104528810A (en) * | 2015-01-20 | 2015-04-22 | 天津大学 | Preparation method for preparing stannic oxide nanorod cluster by using one-step hydrothermal method |
CN105293571A (en) * | 2015-11-30 | 2016-02-03 | 天津工业大学 | Method for directly preparing stannic oxide nano-particles by using metallic tin |
US20170194651A1 (en) * | 2015-12-30 | 2017-07-06 | Robert Bosch Gmbh | Metal oxide cathode |
US10892492B2 (en) * | 2015-12-30 | 2021-01-12 | Robert Bosch Gmbh | Metal oxide cathode |
US11053598B2 (en) * | 2017-02-16 | 2021-07-06 | Honda Motor Co., Ltd. | Method for producing core shell nanoparticles |
US20180230611A1 (en) * | 2017-02-16 | 2018-08-16 | Honda Motor Co., Ltd. | Method for producing core shell nanoparticles |
CN110142049A (en) * | 2019-05-15 | 2019-08-20 | 广州大学 | A kind of cadmium sulfide and zinc sulphide nucleocapsid structure catalysis material preparation method for hydrogen manufacturing |
CN114162851A (en) * | 2020-09-10 | 2022-03-11 | 中国民航大学 | Nano flower-like SnO2One-step template-free hydrothermal preparation method of gas-sensitive material |
CN114162851B (en) * | 2020-09-10 | 2023-09-15 | 中国民航大学 | Nanometer flower-like SnO 2 One-step template-free hydrothermal preparation method of gas-sensitive material |
Also Published As
Publication number | Publication date |
---|---|
EP2038899A2 (en) | 2009-03-25 |
CN101501790A (en) | 2009-08-05 |
WO2008048716A3 (en) | 2008-09-04 |
US20130130109A1 (en) | 2013-05-23 |
WO2008048716A2 (en) | 2008-04-24 |
EP2038899A4 (en) | 2015-05-20 |
US8945504B2 (en) | 2015-02-03 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US8945504B2 (en) | Nanostructured metal oxides comprising internal voids and methods of use thereof | |
Poolakkandy et al. | Soft-template-assisted synthesis: a promising approach for the fabrication of transition metal oxides | |
Opra et al. | Recent efforts in design of TiO2 (B) anodes for high-rate lithium-ion batteries: A review | |
Zhou et al. | MOF derived metal oxide composites and their applications in energy storage | |
Lan et al. | Confined interfacial monomicelle assembly for precisely controlled coating of single-layered titania mesopores | |
Wei et al. | Metal oxide hollow nanostructures: Fabrication and Li storage performance | |
Hu et al. | Hollow/porous nanostructures derived from nanoscale metal–organic frameworks towards high performance anodes for lithium-ion batteries | |
Liu et al. | Anisotropic Co 3 O 4 porous nanocapsules toward high-capacity Li-ion batteries | |
Wu et al. | Nanostructured metal oxide-based materials as advanced anodes for lithium-ion batteries | |
Chen et al. | SnO2‐based nanomaterials: synthesis and application in lithium‐ion batteries | |
Chen et al. | SnO2 hollow structures and TiO2 nanosheets for lithium-ion batteries | |
Ye et al. | Morphology‐controlled synthesis of SnO2 nanotubes by using 1D silica mesostructures as sacrificial templates and their applications in lithium‐ion batteries | |
Liu et al. | Template-directed metal oxides for electrochemical energy storage | |
Zhu et al. | Self-assembled 3D flower-like hierarchical β-Ni (OH) 2 hollow architectures and their in situ thermal conversion to NiO | |
Li et al. | Synthesis and application of nanocages in supercapacitors | |
EP3617147B1 (en) | Process for preparing titanic acid salt, titanic acid, and titanium oxide having controllable particle size and hierarchical structure | |
US10381641B2 (en) | Hollow silicon structures for use as anode active materials in lithium-ion batteries | |
CN109745929B (en) | Preparation method of molybdenum oxide/molybdenum disulfide core-shell microspheres | |
US20170352446A1 (en) | Graphene/porous iron oxide nanorod composite and manufacturing method thereof | |
JPWO2005047199A1 (en) | Nano-sized microcrystalline oxide-glass composite mesoporous powder or thin film, method for producing the same, various devices using the same powder or thin film, secondary battery and lithium storage device | |
Zhu et al. | Synthesis of monodisperse mesoporous TiO2 nanospheres from a simple double-surfactant assembly-directed method for lithium storage | |
Li et al. | Acetic acid-induced preparation of anatase TiO 2 mesocrystals at low temperature for enhanced Li-ion storage | |
Zhu et al. | Recent progress on nanostructured transition metal oxides as anode materials for lithium-ion batteries | |
Ma et al. | Synthesis and applications of one-dimensional porous nanowire arrays: a review | |
Zheng et al. | Fabrication of flower-like mesoporous TiO2 hierarchical spheres with ordered stratified structure as an anode for lithium-ion batteries |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: CORNELL RESEARCH FOUNDATION, INC., NEW YORK Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ARCHER, LYNDEN A;LOU, XIONG WEN;REEL/FRAME:021956/0254 Effective date: 20081205 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |
|
AS | Assignment |
Owner name: NATIONAL SCIENCE FOUNDATION, VIRGINIA Free format text: CONFIRMATORY LICENSE;ASSIGNOR:CORNELL UNIVERSITY;REEL/FRAME:044495/0943 Effective date: 20171116 |