WO2001099127A2 - Coated metallic particles, methods and applications - Google Patents

Coated metallic particles, methods and applications Download PDF

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Publication number
WO2001099127A2
WO2001099127A2 PCT/US2001/019368 US0119368W WO0199127A2 WO 2001099127 A2 WO2001099127 A2 WO 2001099127A2 US 0119368 W US0119368 W US 0119368W WO 0199127 A2 WO0199127 A2 WO 0199127A2
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Prior art keywords
suoxyl
coated
particles
metauic
cross
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PCT/US2001/019368
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French (fr)
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WO2001099127A3 (en
Inventor
Johna Leddy
Shelley D. Minteer
Wayne L. Gellett
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The University Of Iowa Research Foundation
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Priority to US10/363,996 priority Critical patent/US7585543B2/en
Priority to AU2001266979A priority patent/AU2001266979A1/en
Publication of WO2001099127A2 publication Critical patent/WO2001099127A2/en
Publication of WO2001099127A3 publication Critical patent/WO2001099127A3/en
Priority to US12/537,976 priority patent/US20100092779A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C1/00—Magnetic separation
    • B03C1/005—Pretreatment specially adapted for magnetic separation
    • B03C1/01—Pretreatment specially adapted for magnetic separation by addition of magnetic adjuvants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
    • B22F1/102—Metallic powder coated with organic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
    • B22F1/103—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material containing an organic binding agent comprising a mixture of, or obtained by reaction of, two or more components other than a solvent or a lubricating agent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/16—Metallic particles coated with a non-metal
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/0027—Thick magnetic films
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/0551—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0552—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 in the form of particles, e.g. rapid quenched powders or ribbon flakes with a protective layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0572—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes with a protective layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/10—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure
    • H01F1/11—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure in the form of particles
    • H01F1/112—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure in the form of particles with a skin
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
    • H01F1/20—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/34—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites
    • H01F1/36—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites in the form of particles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/14—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates
    • H01F41/16—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates the magnetic material being applied in the form of particles, e.g. by serigraphy, to form thick magnetic films or precursors therefor
    • 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
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88—Processes of manufacture
    • H01M4/8817—Treatment of supports before application of the catalytic active composition
    • 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
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/9041—Metals or alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • 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
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/8647—Inert electrodes with catalytic activity, e.g. for fuel cells consisting of more than one material, e.g. consisting of composites
    • 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
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • 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 generally to new magnetic materials and new metallic particles ⁇ and methods for their manufacture.
  • the present invention relates to new magnetic materials and new metallic particles, methods of making them (including methods of siloxyl coating them), and methods of using them, for example, to prepare magnetically modified electrodes for fuel cells, electrolytic cells, and batteries that thereby benefit from resulting enhanced or otherwise beneficially altered function.
  • paramagnetic microparticles are expensive and not of uniform size. For example, the paramagnetic microparticles are reported to be 1-2 ⁇ m in diameter, but microscopy indicates they are 0.1 -10 ⁇ m in diameter. In addition, each batch has a different magnetic content. These variations in size and magnetic field strength introduce additional experimental variables that diniinish reprodutibility and greatly reduce experimental precision. Paramagnetic microparticles can cost approximately $400 per gram.
  • new magnetic micromaterials, such as magnetic microparticles that have higher magnetic field strengths in order to more greatly facilitate magnetically susceptible chemical reactions and other magnetically susceptible processes.
  • magnetic microparticles with thinner coatings to permit advantageous use of their magnetic fields, which taper off with distance by a function of the inverse cube of the distance x from the particle: x 3 .
  • An object of the present invention is to provide solutions to the above described disadvantages of prior art metallic particles and magnetic particles, and to provide at least the advantages described hereinafter.
  • functional chemical groups for example, including catalysts, enzymes, enzyme active sites, enzyme regulatory sites, enzyme inhibitory sites, ion exchange molecules, binders, Ugand binding sites, hydrophilic molecules, hydrophobic molecules, and combinations thereof.
  • Figure 1 outiines steps used to prepare magnetic microparticles (samarium cobalt, magnetite, nickel, and iron oxides in general, as weU as metalUc and non-metalUc microparticles in general);
  • Figure 2 summarizes the basic chemistry of the sUoxyl coating procedure;
  • Figure 3 outiines steps of the siloxyl coating procedure;
  • Figure 5 outiines steps for preparing a magnetic electrode with sUoxyl coated magnetic particles;
  • Figure 6 shows 100 mV/s cycHc voltammograms of tris(2,2'-bipyridyl) ruthenium (II) in a siloxyl coated samarium cobalt microparticle/Nafion® composite and a Nafion® film;
  • Figure 7 shows 100 mV/s cycHc voltammograms of tris(2,2'-bipyridyl) ruthenium (II) in a samarium cobalt mUUparticle/Nafion® composite and a Nafion® film;
  • Figure 8 shows 100 mV/s cycUc voltammograms of tris(2,2'-bipyridyi) ruthenium (II) in a sUoxyl coated magnetite microparticle/Nafion® composite and a Nafion® film;
  • Figure 9 shows 100 mV/s cycUc voltammograms of tris(2,2'-bipyridy ⁇ ) ruthenium (II) in a sUoxyl coated nickel microparticle/Nafion® composite and a Nafion® film. Nickel electrode data were recorded in an external magnetic field.
  • metalUc is defined to include any element, compound, or rnixture that comprises an element that can be a metal, a semi-metal, or a semiconductor; for example, sUver and sUver chloride are both metalUc according to this definition, as are Si and Si0 2 .
  • the new metalUc and magnetic micromaterials of the present invention have a range of material costs, depending on the specific material.
  • the new metallic and magnetic materials of the present invention include particles made of magnetite and other iron oxides, samarium cobalts of various stoichiometries, nickel, neodymium iron boron, and metalUc particles in general.
  • New magnetic microparticles of the present invention were made by milling metallic or magnetic materials, and then coating the resulting microparticles with silanes to provide a protective sUoxyl coating.
  • Polysciences paramagnetic microparticles are made of iron oxide, and are shrouded in polystyrene.
  • the new magnetic materials of the present invention comprise materials that faU into several categories. Magnetite and iron oxides in general, and samarium cobalt microparticles, for example, are paramagnetic, which means that, once magnetized, they wiU sustain a magnetic field in the absence of an external magnetic field.
  • Superparamagnetic materials are superparamagnetic, which means that they require an external magnet in order to sustain a magnet field themselves.
  • Superparamagnetic materials also comprise otherwise paramagnetic materials when the particles are sufficiently smaU ( ⁇ or ⁇ 0.5 ⁇ m), so that they are not capable of sustaining a magnetic field in the absence of an external magnet.
  • Samarium cobalt magnets are very strong rare earth magnets, but are not as strong as neodymium iron boron magnets.
  • the sUane chemisorption methodology of the present invention has been used to produce a chemicaUy inert protective coating for neodymium i on boron when at least two coatings are appUed onto such particles.
  • the silane chemisorption methodology of the present invention has been found to be effective with appUcation of a single coating on samarium cobalt, magnetite, and nickel microparticles, as herein below described.
  • magnetic microparticles and metalUc microparticles are made (as is outlined in Fig. 1) by miUing magnetic or metalUc materials to diameters of about 5 ⁇ m (usual diameter range ⁇ 2 to ⁇ 10 ⁇ m, with outside limits of ⁇ 0J to ⁇ 20 ⁇ m) using, for example, a Brinkmann Centrifugal BaU M l Model SI 000.
  • a roughly 10 mL volume of dry magnetic or metalUc material with initial material sizes having diameters of less than about 2 mm is selected 102, placed in a dry baU rnUl 104, and ground in a 50 mL zirconia grinding set (zirconia internal surface, plus zirconia grinding baUs) for about 2 hours at a turntable speed setting of about 85 106. This produces particles with a diameter of about
  • zirconia jar and grinding balls are washed thoroughly with 18 M ⁇ water, and dried before new magnetic or metalUc samples are introduced. Materials other than zirconia are contemplated for this methodology, as long as they are harder than the particles being miUed.
  • This procedure is appropriate for smaUer laboratory uses.
  • larger industrial uses wUl benefit from scaled-up procedures, in which, for example, larger dry ball mills are used, and the starting dry magnetic or metaUic particles are larger, for example, 2-3 cm in diameter. MilUng times are generaUy longer than the above when the starting materials have larger diameters.
  • this procedure can be used advantageously for preparation of metalUc microparticles in general, not just for magnetic microparticles.
  • the nickel powder is a porous filamentary powder, so actual particle density is much less than the density of nickel metal given in Table 1.
  • the magnetite (Fe 3 0 4 ) and samarium cobalt (Sm 2 Co 7 ) materials purchased without external magnetization, are inherendy magnetizable materials. Other iron oxides and samarium cobalt materials will benefit also from the sUoxyl coating procedure of the present invention.
  • chemicaUy inert can mean relativeyl chemicaUy inert, for example, to aUow chemical attachment of selected chemical moieties of any desired sort.
  • this procedure see Fig. 2 for the general chemical concept of the procedure; see Fig.
  • 3 for steps of the procedure is commenced by mixing the magnetic or metaUic microparticles (about 1 gram of microparticles in about 25 mL of solution; relative amounts may be varied according to a particular use) in a roughly 50/50 (v/v) solution of 3-aminopropyltrimethoxysilane (Aldrich) /toluene (generaUy, an X-C ⁇ -trialkoxysilane in an aromatic organic solvent, including in multicycUc aromatics and heterocycUc aromatics, or in a saturated or unsaturated alkane of C 5 or longer) 302, and vigorous shaking or shaking by hand [with frequent inversions (roughly one inversion per second) to maintain the magnetic microparticles in suspension when a vigorous shaking protocol is not used] for about 4 hours when the procedure is conducted at room temperature (roughly 17°C to about 25°C) 304.
  • 3-aminopropyltrimethoxysilane Aldrich
  • Figure 3 displays the general formula for a suitable sUane according to the present invention, X-C v -trialkoxysUane, where X is a cross Unkable group, for example, an amide, an amino, a thiol, a chloro, a bromo, an iodo, a thiol, a carboxy, an aldehyde, an alcohol, an alkoxy, a sulfonyl, a carbonyl, a methacryl, a nittile, or other simUarly reactive group, and where each X group is matched with a cross Unking agent that is reactive toward that X group; x can equal from 1 to about 20; C x is a Unear or branched carbon chain that is saturated or unsaturated, and that also can comprise a cycUc group with the proviso that the cycUc group must be separated from the trialkoxysilane moiety by a carbon chain
  • Room temperature encompasses a temperature range from about 17°C to about 25°C. "Frequent inversions” are roughly an inversion per second, though a range from about an inversion per 2 or 3 seconds to 2-4 inversions per second provide adequate maintenance of a suspension to promote siloxyl coating of the magnetic microparticles, metalUc microparticles, or other particles.
  • the magnetic microparticles, metalUc microparticles, or other particles are then allowed to settle and the supernate decanted 306, and rinsed several times with toluene or other organic solvent (such as an aromatic organic solvent, including multicycUc aromatics and heterocycUc aromatics, such as xylene, benzene, substituted benzenes, etc.) or with a saturated or unsaturated alkane of C 5 or longer (preferably saturated) 308, and dried by dessication (for example, by vacuum dessication) or other drying procedure 310.
  • toluene or other organic solvent such as an aromatic organic solvent, including multicycUc aromatics and heterocycUc aromatics, such as xylene, benzene, substituted benzenes, etc.
  • a saturated or unsaturated alkane of C 5 or longer (preferably saturated) 308 preferably saturated
  • the magnetic or other metalUc particles can be separated from the organic solvent by methods other than settiing and decanting of supernate, for example, filtration, centrifugation, use of a magnet, etc.
  • the magnetic microparticles are suspended in a roughly 50/50 (v/v) cross Unking solution of about 50% purity cross Unking agent ethylene glycol diglycidyl ether (Aldrich) /water 312, and vigorously shaken or shaken by hand [with frequent inversions (about once per second; see above) to maintain the magnetic microparticles in suspension] for about 4 hours when the procedure is executed at room temperature (range from about 17°C to about 25°C) 314.
  • cross Unking solution means a solution comprising at least one cross Unking agent, and also includes a pure cross Unking agent. Higher temperatures may be employed, for example, at least as high as about 70°C.
  • Other cross Unking agents can be utiUzed advantageously in this procedure, for example, ethylene glycol dimethacrylate, 2- ethylhexylglycidyl ether, ethylene glycol bis [pentakis (glycidyl aUyl ether)] ether, 1,4-butanediol glycidyl ether, 4-tert-butyl phenyl glycidyl ether, N,N'-bis (acryloyl) cystamine, nitrUotriacetic acid tri (N-succinimidyl) ester, and 4-azidophenyl isothiocyanate, as long as they are reactive toward the X group of the X-C -trialkoxysUane.
  • Each cross Unking agent wiU have a preferred temperature range and set of reaction conditions.
  • the cross Unking reaction is typicaUy run in an aqueous solution.
  • the relative volume of cross Unking solution to microparticles may be varied, and are selected so that there is roughly an equaUty between number of cross Unking groups and reactive X groups, or an excess number of cross Unking groups over the number of reactive X groups.
  • the resulting coated (and cross Unked) magnetic microparticles or metalUc microparticles are then aUowed to settle and the supernate decanted (or other separation procedure, as indicated above) 316, and the magnetic microparticles rinsed several times with 18 M ⁇ water 318, and dried by dessication or other drying procedure 320.
  • large samarium cobalt millipax ⁇ cles are prepared in the same way as the micropa ⁇ cies except that the miUiparticles are wet/ damp at commencement of the coating process 402.
  • the magnetic microparticles are wet/ damp at time of introduction to the aminopropyltrimethoxysUane/toluene mixture (or, generaUy, amino-C ⁇ .- alkoxysilane in an organic solvent, as described above), they clump or coagulate to form larger miUiparticles during the shaking/ suspension process 404.
  • these larger miUiparticles can constitute an agglomeration of small microparticles; alternatively, a samarium cobalt miUiparticle also can constitute a single large rniUiparticle.
  • a resulting single sUoxyl coating on the magnetic microparticles or other particles is in the range of about 10 Angstroms to about 30 Angstroms thick. For many kinds of particles, a single coating suffices.
  • the process may be repeated to form one or more additional coatings, as is necessary with neodymium iron boron particles.
  • neodymium iron boron microparticles With neodymium iron boron microparticles, a single sUoxyl coating procedure results in uncoated projections that are read y reactive in an appropriate solution; whereas appUcation of a second siloxyl coating procedure produces neodymium iron boron microparticles that are fully resistant to surface reactions, including in a Nafion® testing suspension (superacid; see below).
  • an improved procedure introduces an additional step that produces a more stable second coat, namely, a heating step that foUows the first coating, and before appUcation of the second coating: the single coated neodymium iron boron particles are annealed by heating to a temperature less than the curie temperature (the temperature at which magnetic properties are lost by the particular material).
  • An exemplary additional step is to heat the single coated neodymium iron boron particles to about 450°C (+ about 20 to 30°C) in a nitrogen atmosphere for about an hour (could be varied between about half an hour and about 2 hours). This step drives off -OH and H 2 0 groups, and produces a glassy Uke first coating. Upon cooUng, the single coated particles can then be subjected to the same procedure that was used to produce the first coating.
  • Composites are formed by co-casting a 5% by weight (w/w) suspension of Nafion® 1100 in lower aUphatic alcohols (Aldrich) and the sUoxyl coated magnetic microparticles.
  • the volumes of the coated magnetic microparticles and the Nafion®/lower aUphatic alcohol solution are selected so as to yield a dry composite with about 15% by volume as sUoxyl coated magnetic microparticles, and about 85% as Nafion®.
  • the volume of microparticles in the dry composite is less than about 7.5%, the composites do not produce sufficiently large magnetic field effects.
  • the volume of microparticles in the dry composite is more than about 20%, the composites are prone to cracking.
  • the preferred range for the volume of iron oxide microparticles in the dry composite is about 9% to about 19%.
  • the beneficial volume range for the dry composite wUl vary according to the magnetic field strength of the particles, as well as the size of the particles. For example, when neodymium iron boron magnets (with stronger
  • the preferred volume range for the dry composite may vary from about 5% to more than 20%, for example, to about 30%.
  • sUoxyl coated magnetic microparticles were placed in a Nafion® suspension (superacid) for a week to see if corrosion would occur. No corrosion was observed either visuaUy or electrochemicaUy.
  • ion exchange polymers other than Nafion® may beneficiaUy be used in practice of the present invention, for example, including polystyrene sulfonates, polyvinylpyridines, and Flemion®, etc.
  • these polymers may be modified by various means to alter physical and chemical properties thereof.
  • Reagents for CycUc Noltammetry CycUc voltammetry was performed on tris (2,2'- bipyridyl) ruthenium (II) chloride hexahydrate (Ru(bpy) 3 +2 ; Aldrich) through the composites.
  • AU solutions were made in 18 M ⁇ (MilH-Q) water. The concentration of the redox species was 1.0 mM with 0.10 M nitric acid electrolyte.
  • Electrode Preparation for CycUc Noltammetry The general procedure foUowed for preparing a glassy carbon electrode is summarized in Figure 5. This procedure was appUed to a glassy carbon disk working electrode. However, the procedure may equaUy weU be appUed to other electrodes that faU within the contemplated scope of appUcation of sUoxyl coated magnetic or other particles according to practice of the instant invention, for example, to electrodes made of metals, semi-metals, and semiconductors, including the alkaH metals, the alkaUne earths, the transition metals, the lanthanides and actinides, the elements of Groups
  • IIIA, IN A, and NIA including, for example, gold, platinum, palladium, steel, carbon (for example, pyrolytic graphite, vitreous carbon, carbon black, graphite powder, highly ordered pyrolytic graphite, carbon paste, graphite composites, wax impregnated graphite, etc.), lead, iron, copper, aluminum, antimony, chromium, tin, s icon, nickel, germanium, manganese, magnesium, mercury, molybdenum, neodymium, galUum, boron, ruthenium, tungsten, titanium, zinc, and zirconium, including their oxides, nitrides, aUoys, chalcogenides, haUdes, sulfides, selenides, teUurides, phosphides, aUoys, and arsenides, etc., and mixtures thereof.
  • carbon for example, pyrolytic graphite, vitreous carbon, carbon black, graphit
  • the present procedure may also be appUed to conducting organic and other polymers, including polyanilines, polypyrroles, polythiophenes, polyacetylenes, and derivatives thereof, as well as polymers comprising such components as graphite fibers, carbon nanotubes, etc.
  • the procedure may be appUed to electrodes made of any material that conducts electrons, including, for example, sodium electrodes that are operated in a non-aqueous and non-oxygen environment.
  • the procedure may also be appUed to semiconductor electrodes, including doped and intrinsic.
  • the procedure may also be appUed to boron nitride electrodes.
  • the electrode was then cleaned 506 by sonicating for about 5 minutes (range: about 1 to about 20 minutes) in 18 M ⁇ water to remove remaining alumina, soaking in concentrated nitric acid for about 2 minutes (approximate range: about 1 minute to about 10 minutes), and thoroughly rinsing with 18 M ⁇ water.
  • dilute nitric acid may be used in place of concentrated nitric acid.
  • the electrode surface was then modified with either a Nafion® film or a magnetic microparticle/Nafion® composite.
  • Nafion® films were prepared by pipetting an appropriate volume of about 5% by weight (w/w) Nafion® solution (the 5% by weight Nafion® polymer is mixed into a solution that is roughly 50% (v/v) 18 M ⁇ water and roughly 50% lower, straight chain aUphatic alcohols) onto the electrode surface.
  • Nafion® polymer may also advantageously be mixed with other amounts of aqueous solvent, as weU as with other solvents, for example, with an alcohol, in order to change porosity properties of the resulting Nafion® composite.
  • the magnetic microparticle/Nafion® composites (containing sUoxyl coated magnetic microparticles) were prepared by pipetting an appropriate volume of composite stock solution onto the electrode surface in the presence of an external magnet 508, the shape of which affects the kinds of piUared composite structures that result, as is known in the art.
  • the resulting Nafion® coated or Nafion®-magnetic composite coated electrode was then dried 510 by vacuum dessication or other drying method.
  • Samarium cobalt composites were handled siirrUarly, except that the electrodes with composite and samarium cobalt were placed in an external magnet of a desired shape (again, shape of magnet being selected based on the desired shape of composite piUars)
  • the composite stock solution was prepared by adding appropriate fractions of 5% by weight (w/v) Nafion® solution and dry magnetic microparticles (sUoxyl coated) together. The fractions are calculated so that the dry composite film is composed of about 15% by volume as sUoxyl coated magnetic microparticles (range about 9% to about 19%; see above for notes on other det Us and other ranges that apply to other magnetic or metalUc materials) and about 85% by volume as Nafion®. The film thicknesses were about 54 ⁇ m.
  • One exceptional study was performed on an electrode modified with one large samarium cobalt particle.
  • These films were prepared by centering a roughly 1 mm diameter sUoxyl coated samarium cobalt particle on the electrode surface, and pipetting the above described 5% by weight (w/w) Nafion® solution over the particle/electrode.
  • the samarium cobalt particle was suspended on the electrode surface with a Nafion® solution.
  • the samarium cobalt particle was not buried inside the film because the particle was much thicker than the film.
  • Electrochemical Measurements The electrochemical flux of Ru(bpy) 3 +2 through the membrane layer to the electrode surface was studied using cycUc voltammetry. Nafion® film and magnetic microparticle/Nafion® composite modified working electrodes were equilibrated in 1.0 mM Ru(bpy) 3 +2 and 0.1 M nitric acid for 4 hours before measurements were taken.
  • the reference electrode was a saturated calomel electrode.
  • the counter electrode was a large platinum gauze spot welded to platinum wire. Data were coUected and analyzed on a Pentium computer interfaced to a BioAnalytical Systems Model 100B/W Potentiostat.
  • CycUc voltammetry was performed at scan rates ranging from 50 to 200 mV/s.
  • electrochemical flux is determined from the measured peak current (z ⁇ ) for reversible electron transfers, and the measured peak current is a function of the extraction coefficient (K ) and the apparent diffusion coefficient (D ⁇ ) of the redox probe in the composite or film.
  • n is the number of electrons transferred
  • F Faraday's constant
  • A is the area of the electrode
  • v is the scan rate
  • € is the porosity of the film
  • C* is the concentration of Ru(bpy) 3 +2 in solution.
  • the porosity of Nafion® films and composites consisting of one bead is approximately 1.0, and the porosity of the magnetic composites is about 0.85. Three repHcates of each experiment were performed.
  • Samarium Cobalt Forming samarium cobalt/Nafion® composites has several engineering problems. Due to the high magnetic field environment of the samarium cobalt magnetic microparticles and the high density of the samarium particles, the samarium cobalt microparticles do not suspend in the Nafion® solution. This causes problems in determining the exact amount of magnetic micromaterial on the electrode surface. Therefore, flux enhancements cannot be quantified with the needed precision. A representative cycHc voltammogram of Ru(bpy) 3 +2 in a samarium cobalt/Nafion® composite and in a Nafion® film is provided in Figure 6.
  • Ru(bpy) 3 +2 is harder to electrolyze in the samarium cobalt composite than it is in Nafion®.
  • the differences in the peak potentials are approximately the same as the ⁇ .- ⁇ JS for the Nafion® films.
  • the peak potentials are asymmetricaUy shifted by only 15 mN because there is a smaUer average magnetic field at the electrode surface.
  • the forward peak potential is shifted +5 mV with respect to Nafion®, and the backward peak potential is shifted -5 mV with respect to Nafion®.
  • the siloxyl coated magnetite composites are similar in morphology to the Polyscience paramagnetic microparticle composite, except the Polyscience paramagnetic icroparticle composites have an orange tint to them, whereas the sUoxyl coated magnetite composites are dark black.
  • SUoxyl coated magnetite microparticles comprise black microparticles
  • Polyscience paramagnetic microparticles comprise dark orange/brown microparticles. The orange brown coloration is due in part to the thick polystyrene shroud around the Polyscience paramagnetic microparticle, and in part to degradation of magnetite to other forms of iron oxide.
  • the siloxyl coated magnetite/Nafion® composites show simHar enhancements in electrochemical flux as probed by cycUc voltammetry. This can be seen from the cycHc voltammograms of Ru(bpy) 3 +2 in a siloxyl coated magnetite/Nafion® composite and in a Nafion® film, as is shown in Figure 8.
  • the differences in the peak potentials ( ⁇ E ⁇ ) are 5 mN larger than the AE p s for the afion® films.
  • the forward peak potential is shifted 48 mN with respect to Nafion®, and the backward peak potential is shifted -33 mN with respect to Nafion®.
  • Nickel SUoxyl coated nickel microparticles form composites that look similar to the composites formed from sUoxyl coated magnetite microparticles.
  • the main functional difference between the two composites is that nickel is a weaker magnetic material.
  • Nickel microparticles are superparamagnetic, so they only sustain a magnetic field in the presence of an external magnetic field. Therefore, the cycUc voltammogram of the sUoxyl coated nickel microparticle/Nafion® composite shown in Figure 9 is in the presence of a 0.2 T external
  • the flux enhancements for sUoxyl coated nickel microparticle/Nafion® composites are less than for sUoxyl coated magnetite microparticles/Nafion® composites.
  • the difference in the peak potentials ( ⁇ E ⁇ ) are 30 mV larger than the ⁇ E ⁇ 's for the Nafion® films.
  • the forward peak potential is shifted 58 mV with respect to Nafion® and the backward peak potential is shifted
  • the porosities of the samarium cobalt miUiparticle composites are approximately 1.0 because a particle consumes only a smaU volume of the polymer composite.
  • the sUoxyl coated magnetic micromaterials appear to be as stable as the Polysciences microspheres.
  • the sUane coated magnetite microparticles, prepared as described herein, show the same flux enhancement as observed for the Polysciences microspheres, within errors of measurement.
  • the sUane coated nickel composites produce much smaUer flux enhancements than the magnetite composites because " nickel is a much weaker magnetic material.
  • the nickel microparticles would not be commerciaUy useful in many technological appUcations because the flux enhancements are so smaU, and they require the presence of an external magnetic field. However, they might constitute acceptable material for a flux throttle or switch, as can iron and cobalt microparticles.
  • the sUane coated samarium cobalt composites have exceUent magnetic benefits even if they have engineering difficulties.
  • the large flux enhancement seen in Figure 5 Ulustrates the usefulness of this magnetic material.
  • sUoxyl coated magnetic microparticles and sUoxyl coated magnetic miUiparticles on kinds of electrodes not specificaUy described herein faU within the intended scope of the present invention.
  • sUoxyl coating of metaUic particles not specificaUy disclosed herein faU within the intended scope of the present invention.
  • magnetic and metalUc materials not specifically Usted herein are intended to be encompassed by the scope of the present invention.

Abstract

New magnetic materials and new metallic particles, new methods of making and using same, for example, to prepare magnetically modified electrodes and fuel cells, and coated metallic particles in general. The present invention discloses methods of preparation of cheaper and more uniformly sized magnetic and metallic microparticles formed from the exemplary materials magnetite, nickel, samarium cobalt and neodymium iron boron. In addition, the present invention discloses methodology for preparation and use of coated magnetic and metallic microparticles, in particular, exemplary siloxyl coating of magnetic particles, metallic particles, and magnetic and metallic microparticles with an exemplary silane, 3-aminopropyltrimethoxysilane, that is cross linked thereon. In addition, methods and results are described for preparing and using larger siloxyl coated samarium cobalt milliparticles. Coated magnetic milliparticles and magnetic microparticles are useful as component of composites that are applied to electrodes to alter electrochemical fluxes across those electrodes, as well as to alter chemical reactions on surfaces of those electrodes, when magnetically susceptible reactions occur there.

Description

NEW MAGNETIC MATERIALS, METALLIC PARTICLES AND METHODS OF MAKING SAME
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to new magnetic materials and new metallic particles^ and methods for their manufacture. In particular, the present invention relates to new magnetic materials and new metallic particles, methods of making them (including methods of siloxyl coating them), and methods of using them, for example, to prepare magnetically modified electrodes for fuel cells, electrolytic cells, and batteries that thereby benefit from resulting enhanced or otherwise beneficially altered function.
2. Background of the Related Art Commercially available paramagnetic microparticles are expensive and not of uniform size. For example, the paramagnetic microparticles are reported to be 1-2 μm in diameter, but microscopy indicates they are 0.1 -10 μm in diameter. In addition, each batch has a different magnetic content. These variations in size and magnetic field strength introduce additional experimental variables that diniinish reprodutibility and greatly reduce experimental precision. Paramagnetic microparticles can cost approximately $400 per gram.
Although this figure may not be great when modifying small 0.45 cm2 electrodes with 3-6 μm thick composites, it becomes significant when the magnetic microparticles are used in larger industrial and commercial applications.
Therefore, a need exists for new magnetic micromaterials and new metallic materials generally, such as magnetic microparticles and metallic microparticles, that are fabricated with more uniformity. In addition, a need exists for new magnetic micromaterials, such as magnetic microparticles, that have higher magnetic field strengths in order to more greatly facilitate magnetically susceptible chemical reactions and other magnetically susceptible processes. In this regard, a need exists for magnetic microparticles with thinner coatings to permit advantageous use of their magnetic fields, which taper off with distance by a function of the inverse cube of the distance x from the particle: x3. Furthermore, a need exists for a method of coating metallic particles in general, for example, to prevent oxidative and other detrimental surface processes and reactions.
The following United States and PCT patent documents to Leddy, et al., are hereby incorporated by reference in their respective entireties: United States Patent Nos. 5,786,040, 5,817,221, 5,871,625, 5,928,804, 5,981,095, and 6,001,248; United States Patent AppHcation
Nos. 08/429,931, 09/047,494, 09/122,861, 09/362,495, 09/429,931, and 09/458,058; PCT AppHcation Nos. PCT/US00/ 15041 and PCT/US00/28242; and Provisional Patent Application Nos. 60/212,630, 60/208,322, 60/159,374, and 60/139,318.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.
SUMMARY OF THE INVENTION An object of the present invention is to provide solutions to the above described disadvantages of prior art metallic particles and magnetic particles, and to provide at least the advantages described hereinafter.
In particular, it is an object of the present invention to provide micromaterials and magnetic microparticles as well as a methodology for producing micromaterials, including magnetic microparticles, that have a high degree of uniformity.
It is another object of the present invention to provide micromaterials and magnetic microparticles as well as a methodology for producing micromaterials, including magnetic microparticles, that have a low variability as to particle size.
It is another object of the present invention to provide micromaterials and magnetic microparticles as well as a methodology for producing micromaterials, including magnetic microparticles, that have a low variability as to magnetic field strength. It is another object of the present invention to provide micromaterials and magnetic microparticles as well as a methodology for producing micromaterials, including magnetic microparticles, that have a relatively uniformly high magnetic field strength. It is another object of the present invention to provide miciOmaterials and magnetic microparticles as well as a methodology for producing micromaterials, including magnetic microparticles, that simultaneously have low variability as to particle size, low variability as to magnetic field strength, and relatively uniformly high magnetic field strength. It is another object of the present invention to provide micromaterials and magnetic microparticles as well as a methodology for producing metallic micromaterials, including metallic microparticles, that have a high degree of uniformity.
It is another object of the present invention to provide micromaterials and magnetic microparticles as well as a methodology for producing metallic micromaterials, including metallic microparticles, that have a low variability as to particle size.
It is another object of the present invention to provide micromaterials and metallic microparticles with at least one chemically inert coating as well as a methodology for producing at least one coating on micromaterials, including on magnetic microparticles and on metallic microparticles generally, to prevent or at least retard surface oxidative processes and surface reactions and surface processes in general, including dissolution, decomposition and any chemical reaction thereat.
It is another object of the present invention to provide micromaterials and metallic microparticles with at least one chemically inert coating as well as a methodology for producing at least one chemically inert coating on micromaterials, including on magnetic microparticles and on metallic microparticles generally, to prevent or at least retard surface oxidative processes and surface reactions and surface processes in general, including dissolution, decomposition and any chemical reaction thereat.
It is another object of the present invention to provide micromaterials and metallic microparticles with at least one chemically inert coating of a siloxyl as well as a methodology for producing at least one chemically inert'coating of a siloxyl on micromaterials, including on magnetic microparticles and on metallic microparticles, to prevent or at least retard surface oxidative processes and surface reactions and surface processes in general, including dissolution, decomposition and any chemical reaction thereat. It is another object of the present invention to provide a methodology for producing at least one chemically inert coating of cross linked 3-aminopropyltrimethoxysilane (or other X-Cx-trialkoxysilane, as defined herein) on micromaterials, including on magnetic microparticles and on metallic microparticles generally, to prevent or at least retard surface oxidative processes and surface reactions and surface processes in general, including dissolution, decomposition and any chemical reaction thereat.
It is another object of the present invention to provide metallic microparticles and magnetic microparticles with at least one chemically inert coating that prevents or at least retards surface oxidative processes and surface reactions and surface processes in general, including dissolution, decomposition and any chemical reaction thereat.
It is another object of the present invention to provide metallic microparticles and magnetic microparticles with a siloxyl coating that prevents or at least retards surface oxidative processes and surface reactions and surface processes in general, including dissolution, decomposition and any chemical reaction thereat. It is another object of the present invention to provide metallic microparticles and magnetic microparticles with at least one chemically inert coating of cross Hnked 3- aminopropyltrirnethoxysilane (or other X-Cv-trialkoxysilane, as defined herein) on micromaterials, including on magnetic microparticles and on metallic microparticles generally, to prevent or at least retard surface oxidative processes and surface reactions and surface processes in general, including dissolution, decomposition and any chemical reaction thereat.
It is another object of the present invention to provide metallic microparticles and magnetic microparticles with at least one covalently bound siloxyl coating that prevents or at least retards surface oxidative processes and surface reactions and surface processes in general, including dissolution, decomposition and any chemical reaction thereat. It is another object of the present invention to provide metallic microparticles and magnetic microparticles with at least one covalently bound siloxyl coating that is cross linked that prevents or at least retards surface oxidative processes and surface reactions and surface processes in general, including dissolution, decomposition and any chemical reaction thereat. It is another object of the present invention to provide metallic microparticles and magnetic microparticles with a plurality of siloxyl coatings that prevent or at least retard surface oxidative processes and surface reactions and surface processes in general, including dissolution, decomposition and any chemical reaction thereat. It is another object of the present invention to provide metallic microparticles and magnetic microparticles with a pluraUty of siloxyl coatings that are cross Unked that prevent or at least retard surface oxidative processes and surface reactions and surface processes in general, including dissolution, decomposition and any chemical reaction thereat.
It is another object of the present invention to provide metalUc microparticles and magnetic microparticles with a pluraUty of chemically inert coatings of cross Unked 3- aminopropylttimethoxysilane (or other X-C^-trialkoxysilane, as defined herein) on micromaterials, including on magnetic microparticles and on metalUc microparticles generally, to prevent or at least retard surface oxidative processes and surface reactions and surface processes in general, including dissolution, decomposition and any chemical reaction thereat. It is another object of the present invention to provide magnetic electrodes with enhanced or altered function (depending on the particular process) comprising siloxyl coated magnetic microparticles.
It is another object of the present invention to provide a methodology for producing magnetically modified electrodes with enhanced or altered function (depending on the particular process) comprising siloxyl coated magnetic microparticles.
It is another object of the present invention to provide a methodology for enhancing or altering fuel cell electrolysis (depending on the particular process) with siloxyl coated magnetic particles.
It is another object of the present invention to provide a methodology for enhancing or altering electrolytic ceU electrolysis (depending on the particular process) with siloxyl coated magnetic particles.
It is another object of the present invention to provide a methodology for enhancing or altering electrolysis (depending on the particular process) at an electrode surface with siloxyl coated magnetic particles. It is another object of the present invention to provide a magnetically modified fuel ceU with enhanced or altered function (depending on the particular process) due to at least one electrode with siloxyl coated magnetic particles.
It is another object of the present invention to provide a magneticaUy modified fuel ceU with enhanced or altered oxidation rates of organic fuels (depending on the particular process) due to at least one electrode with siloxyl coated magnetic particles.
It is another object of the present invention to provide a magneticaUy modified fuel ceU with enhanced oxidation rates of organic fuels as a result of increased tolerance at an anode due to at least one coating thereon containing sUoxyl coated magnetic particles. It is another object of the present invention to provide a magneticaUy modified fuel cell with enhanced oxidation rates of organic fuels as a result of enhanced oxygen kinetics at a cathode due to at least one coating thereon containing siloxyl coated magnetic particles.
It is another object of the present invention to provide a magneticaUy modified electrolytic cell with enhanced or altered function (depending on the particular process) due to at least one electrode with siloxyl coated magnetic particles.
It is another object of the present invention to provide a magneticaUy modified semiconductor electrode with enhanced or altered function (depending on the particular process) due to at least one electrode with sUoxyl coated magnetic particles.
It is another object of the present invention to provide a battery with enhanced or altered function (depending on the particular process) due to at least one electrode with sUoxyl coated magnetic particles.
It is another object of the present invention to provide a surface coating for particles, wherein the surface coating may simultaneously or subsequently modified by including functional chemical groups, for example, including catalysts, enzymes, enzyme active sites, enzyme regulatory sites, enzyme inhibitory sites, ion exchange molecules, binders, Ugand binding sites, hydrophilic molecules, hydrophobic molecules, and combinations thereof.
Additional advantages, objects, and features of the invention wUl be set forth in part in the description which foUows, and in part wiU become apparent to those having ordinary skiU in the art upon examination of the foUowing, or may be learned from practice of the invention. The objects and advantages of the invention may be reaUzed and attained as particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention wiU be described in detail with reference to the foUowing drawings in which Uke reference numerals refer to Uke elements, wherein:
Figure 1 outiines steps used to prepare magnetic microparticles (samarium cobalt, magnetite, nickel, and iron oxides in general, as weU as metalUc and non-metalUc microparticles in general);
Figure 2 summarizes the basic chemistry of the sUoxyl coating procedure; Figure 3 outiines steps of the siloxyl coating procedure;
Figure 4 outlines steps for preparation of siloxyl coated large samarium cobalt milUparticles;
Figure 5 outiines steps for preparing a magnetic electrode with sUoxyl coated magnetic particles; Figure 6 shows 100 mV/s cycHc voltammograms of tris(2,2'-bipyridyl) ruthenium (II) in a siloxyl coated samarium cobalt microparticle/Nafion® composite and a Nafion® film;
Figure 7 shows 100 mV/s cycHc voltammograms of tris(2,2'-bipyridyl) ruthenium (II) in a samarium cobalt mUUparticle/Nafion® composite and a Nafion® film;
Figure 8 shows 100 mV/s cycUc voltammograms of tris(2,2'-bipyridyi) ruthenium (II) in a sUoxyl coated magnetite microparticle/Nafion® composite and a Nafion® film; and
Figure 9 shows 100 mV/s cycUc voltammograms of tris(2,2'-bipyridyι) ruthenium (II) in a sUoxyl coated nickel microparticle/Nafion® composite and a Nafion® film. Nickel electrode data were recorded in an external magnetic field.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The new magnetic micromaterials of the present invention were prepared by use of a milUng process, foUowed by a siloxyl coating procedure, as described hereinafter. These processes and procedures have appHcability to metallic particles generaUy. Herein, "metalUc" is defined to include any element, compound, or rnixture that comprises an element that can be a metal, a semi-metal, or a semiconductor; for example, sUver and sUver chloride are both metalUc according to this definition, as are Si and Si02.
The new metalUc and magnetic micromaterials of the present invention have a range of material costs, depending on the specific material. The new metallic and magnetic materials of the present invention include particles made of magnetite and other iron oxides, samarium cobalts of various stoichiometries, nickel, neodymium iron boron, and metalUc particles in general.
New magnetic microparticles of the present invention were made by milling metallic or magnetic materials, and then coating the resulting microparticles with silanes to provide a protective sUoxyl coating. For reference, Polysciences paramagnetic microparticles are made of iron oxide, and are shrouded in polystyrene. The new magnetic materials of the present invention comprise materials that faU into several categories. Magnetite and iron oxides in general, and samarium cobalt microparticles, for example, are paramagnetic, which means that, once magnetized, they wiU sustain a magnetic field in the absence of an external magnetic field.
Other materials are superparamagnetic, which means that they require an external magnet in order to sustain a magnet field themselves. Superparamagnetic materials also comprise otherwise paramagnetic materials when the particles are sufficiently smaU (< or ~0.5 μm), so that they are not capable of sustaining a magnetic field in the absence of an external magnet. Samarium cobalt magnets are very strong rare earth magnets, but are not as strong as neodymium iron boron magnets. The sUane chemisorption methodology of the present invention has been used to produce a chemicaUy inert protective coating for neodymium i on boron when at least two coatings are appUed onto such particles. On the other hand, the silane chemisorption methodology of the present invention has been found to be effective with appUcation of a single coating on samarium cobalt, magnetite, and nickel microparticles, as herein below described.
Microparticles. In a preferred embodiment, magnetic microparticles and metalUc microparticles are made (as is outlined in Fig. 1) by miUing magnetic or metalUc materials to diameters of about 5 μm (usual diameter range ~ 2 to ~ 10 μm, with outside limits of ~ 0J to ~ 20 μm) using, for example, a Brinkmann Centrifugal BaU M l Model SI 000. A roughly 10 mL volume of dry magnetic or metalUc material with initial material sizes having diameters of less than about 2 mm is selected 102, placed in a dry baU rnUl 104, and ground in a 50 mL zirconia grinding set (zirconia internal surface, plus zirconia grinding baUs) for about 2 hours at a turntable speed setting of about 85 106. This produces particles with a diameter of about
20 μm. Then, to produce smaller microparticles, 2-3 mL of 18 MΩ water is added to the magnetic or metaUic material in the zirconia j r, and the magnetic OΪ metalUc material is ground for an additional roughly 2 hours at a turntable speed setting of about 85 (which is a setting for the Model S1000) 108. The magnetic or metalUc material is then aUowed to dry by vacuum dessication (10~4 torr; however, other values can be used in the procedure) or other drying procedure 110, and subsequently is removed from the zirconia jar. This produces particles with a diameter of about 5 μm (outside range about 0J to about 20 μm). The zirconia jar and grinding balls are washed thoroughly with 18 MΩ water, and dried before new magnetic or metalUc samples are introduced. Materials other than zirconia are contemplated for this methodology, as long as they are harder than the particles being miUed.
This procedure is appropriate for smaUer laboratory uses. However, larger industrial uses wUl benefit from scaled-up procedures, in which, for example, larger dry ball mills are used, and the starting dry magnetic or metaUic particles are larger, for example, 2-3 cm in diameter. MilUng times are generaUy longer than the above when the starting materials have larger diameters. In addition, this procedure (either the laboratory scale or the industrial scale procedure) can be used advantageously for preparation of metalUc microparticles in general, not just for magnetic microparticles.
This methodology was appHed to the magnetic materials samarium cobalt (Sm,Co7; Aldrich) and magnetite (Aldrich). Unmagnetized nickel powder of roughly 2-3 μm diameter (Novamet) was used without milUng. Information on these magnetic materials is provided in
Table 1. The nickel powder is a porous filamentary powder, so actual particle density is much less than the density of nickel metal given in Table 1. The magnetite (Fe304) and samarium cobalt (Sm2Co7) materials, purchased without external magnetization, are inherendy magnetizable materials. Other iron oxides and samarium cobalt materials will benefit also from the sUoxyl coating procedure of the present invention.
Table 1. Magnetic Material Properties
Figure imgf000012_0001
Chemical Coating. Because these magnetic materials corrode (as do metalUc particles in general), it was necessary to shroud the magnetic and metaUic microparticles in at least one chemicaUy inert protective coating [A. HeUer 1997, personal communication; K. Emoto, J.M.
Harris &J.M.N. Alstine 1996, Anal Chem. 68: 3751-3757], where "chemicaUy inert" can mean relativeyl chemicaUy inert, for example, to aUow chemical attachment of selected chemical moieties of any desired sort. In a preferred embodiment, this procedure (see Fig. 2 for the general chemical concept of the procedure; see Fig. 3 for steps of the procedure) is commenced by mixing the magnetic or metaUic microparticles (about 1 gram of microparticles in about 25 mL of solution; relative amounts may be varied according to a particular use) in a roughly 50/50 (v/v) solution of 3-aminopropyltrimethoxysilane (Aldrich) /toluene (generaUy, an X-Cλ-trialkoxysilane in an aromatic organic solvent, including in multicycUc aromatics and heterocycUc aromatics, or in a saturated or unsaturated alkane of C5 or longer) 302, and vigorous shaking or shaking by hand [with frequent inversions (roughly one inversion per second) to maintain the magnetic microparticles in suspension when a vigorous shaking protocol is not used] for about 4 hours when the procedure is conducted at room temperature (roughly 17°C to about 25°C) 304. Higher temperatures suffice for the reaction, as long as the mixture/suspension does not boU, which is a function of the organic solvent's boiUng point. Thus, temperature ranges at least as high as 70°C to 140°C are possible for this reaction, depending upon the choice of organic solvent with an appropriate boiling point. The relative volumes of sUane/organic solvent, and microparticles/solution of sUane/organic solvent, are governed by the relative amounts of reactive sUane groups to oxide and/or hydroxide groups
40- on the metaUic or magnetic microparticles; in particular, there should be an excess of reactive sUane groups over the number of reactive oxide and/or hydroxide groups with which sUoxyl covalent bonds are to take place.
Figure 3 displays the general formula for a suitable sUane according to the present invention, X-Cv-trialkoxysUane, where X is a cross Unkable group, for example, an amide, an amino, a thiol, a chloro, a bromo, an iodo, a thiol, a carboxy, an aldehyde, an alcohol, an alkoxy, a sulfonyl, a carbonyl, a methacryl, a nittile, or other simUarly reactive group, and where each X group is matched with a cross Unking agent that is reactive toward that X group; x can equal from 1 to about 20; Cx is a Unear or branched carbon chain that is saturated or unsaturated, and that also can comprise a cycUc group with the proviso that the cycUc group must be separated from the trialkoxysilane moiety by a carbon chain that is at least 2 carbons in length; and trialkoxysUane comprises alkoxy groups that independently can be methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, or phenoxy (which may optionaUy be substituted). Room temperature encompasses a temperature range from about 17°C to about 25°C. "Frequent inversions" are roughly an inversion per second, though a range from about an inversion per 2 or 3 seconds to 2-4 inversions per second provide adequate maintenance of a suspension to promote siloxyl coating of the magnetic microparticles, metalUc microparticles, or other particles. The magnetic microparticles, metalUc microparticles, or other particles are then allowed to settle and the supernate decanted 306, and rinsed several times with toluene or other organic solvent (such as an aromatic organic solvent, including multicycUc aromatics and heterocycUc aromatics, such as xylene, benzene, substituted benzenes, etc.) or with a saturated or unsaturated alkane of C5 or longer (preferably saturated) 308, and dried by dessication (for example, by vacuum dessication) or other drying procedure 310. The magnetic or other metalUc particles can be separated from the organic solvent by methods other than settiing and decanting of supernate, for example, filtration, centrifugation, use of a magnet, etc. Once dry, the magnetic microparticles are suspended in a roughly 50/50 (v/v) cross Unking solution of about 50% purity cross Unking agent ethylene glycol diglycidyl ether (Aldrich) /water 312, and vigorously shaken or shaken by hand [with frequent inversions (about once per second; see above) to maintain the magnetic microparticles in suspension] for about 4 hours when the procedure is executed at room temperature (range from about 17°C to about 25°C) 314. The phrase "cross Unking solution" means a solution comprising at least one cross Unking agent, and also includes a pure cross Unking agent. Higher temperatures may be employed, for example, at least as high as about 70°C. Other cross Unking agents can be utiUzed advantageously in this procedure, for example, ethylene glycol dimethacrylate, 2- ethylhexylglycidyl ether, ethylene glycol bis [pentakis (glycidyl aUyl ether)] ether, 1,4-butanediol glycidyl ether, 4-tert-butyl phenyl glycidyl ether, N,N'-bis (acryloyl) cystamine, nitrUotriacetic acid tri (N-succinimidyl) ester, and 4-azidophenyl isothiocyanate, as long as they are reactive toward the X group of the X-C -trialkoxysUane. Each cross Unking agent wiU have a preferred temperature range and set of reaction conditions. The cross Unking reaction is typicaUy run in an aqueous solution. The relative volume of cross Unking solution to microparticles may be varied, and are selected so that there is roughly an equaUty between number of cross Unking groups and reactive X groups, or an excess number of cross Unking groups over the number of reactive X groups. The resulting coated (and cross Unked) magnetic microparticles or metalUc microparticles are then aUowed to settle and the supernate decanted (or other separation procedure, as indicated above) 316, and the magnetic microparticles rinsed several times with 18 MΩ water 318, and dried by dessication or other drying procedure 320.
As is summarized in Figure 4, large samarium cobalt millipaxάcles are prepared in the same way as the micropaϊάcies except that the miUiparticles are wet/ damp at commencement of the coating process 402. When the magnetic microparticles are wet/ damp at time of introduction to the aminopropyltrimethoxysUane/toluene mixture (or, generaUy, amino-Cλ.- alkoxysilane in an organic solvent, as described above), they clump or coagulate to form larger miUiparticles during the shaking/ suspension process 404. Thus, these larger miUiparticles can constitute an agglomeration of small microparticles; alternatively, a samarium cobalt miUiparticle also can constitute a single large rniUiparticle. The other steps (406, 408, 410, 412,
414, 416, 418, and 420, respectively) are identical to respective even numbered steps 306 to 320 of Figure 3.
A resulting single sUoxyl coating on the magnetic microparticles or other particles is in the range of about 10 Angstroms to about 30 Angstroms thick. For many kinds of particles, a single coating suffices. The process may be repeated to form one or more additional coatings, as is necessary with neodymium iron boron particles. With neodymium iron boron microparticles, a single sUoxyl coating procedure results in uncoated projections that are read y reactive in an appropriate solution; whereas appUcation of a second siloxyl coating procedure produces neodymium iron boron microparticles that are fully resistant to surface reactions, including in a Nafion® testing suspension (superacid; see below). However, an improved procedure introduces an additional step that produces a more stable second coat, namely, a heating step that foUows the first coating, and before appUcation of the second coating: the single coated neodymium iron boron particles are annealed by heating to a temperature less than the curie temperature (the temperature at which magnetic properties are lost by the particular material). An exemplary additional step is to heat the single coated neodymium iron boron particles to about 450°C (+ about 20 to 30°C) in a nitrogen atmosphere for about an hour (could be varied between about half an hour and about 2 hours). This step drives off -OH and H20 groups, and produces a glassy Uke first coating. Upon cooUng, the single coated particles can then be subjected to the same procedure that was used to produce the first coating.
Preparation of Composites. Composites are formed by co-casting a 5% by weight (w/w) suspension of Nafion® 1100 in lower aUphatic alcohols (Aldrich) and the sUoxyl coated magnetic microparticles. For iron oxide microparticles, the volumes of the coated magnetic microparticles and the Nafion®/lower aUphatic alcohol solution are selected so as to yield a dry composite with about 15% by volume as sUoxyl coated magnetic microparticles, and about 85% as Nafion®. When the volume of microparticles in the dry composite is less than about 7.5%, the composites do not produce sufficiently large magnetic field effects. When the volume of microparticles in the dry composite is more than about 20%, the composites are prone to cracking. The preferred range for the volume of iron oxide microparticles in the dry composite is about 9% to about 19%. However, note that the beneficial volume range for the dry composite wUl vary according to the magnetic field strength of the particles, as well as the size of the particles. For example, when neodymium iron boron magnets (with stronger
43- magnetic fields) are used, the preferred volume range for the dry composite may vary from about 5% to more than 20%, for example, to about 30%.
To test the stabiHty of resulting microparticles, sUoxyl coated magnetic microparticles were placed in a Nafion® suspension (superacid) for a week to see if corrosion would occur. No corrosion was observed either visuaUy or electrochemicaUy.
It is also important to note that ion exchange polymers other than Nafion® may beneficiaUy be used in practice of the present invention, for example, including polystyrene sulfonates, polyvinylpyridines, and Flemion®, etc. In addition, these polymers may be modified by various means to alter physical and chemical properties thereof. Reagents for CycUc Noltammetry. CycUc voltammetry was performed on tris (2,2'- bipyridyl) ruthenium (II) chloride hexahydrate (Ru(bpy)3 +2; Aldrich) through the composites. AU solutions were made in 18 MΩ (MilH-Q) water. The concentration of the redox species was 1.0 mM with 0.10 M nitric acid electrolyte.
Electrode Preparation for CycUc Noltammetry. The general procedure foUowed for preparing a glassy carbon electrode is summarized in Figure 5. This procedure was appUed to a glassy carbon disk working electrode. However, the procedure may equaUy weU be appUed to other electrodes that faU within the contemplated scope of appUcation of sUoxyl coated magnetic or other particles according to practice of the instant invention, for example, to electrodes made of metals, semi-metals, and semiconductors, including the alkaH metals, the alkaUne earths, the transition metals, the lanthanides and actinides, the elements of Groups
IIIA, IN A, and NIA, including, for example, gold, platinum, palladium, steel, carbon (for example, pyrolytic graphite, vitreous carbon, carbon black, graphite powder, highly ordered pyrolytic graphite, carbon paste, graphite composites, wax impregnated graphite, etc.), lead, iron, copper, aluminum, antimony, chromium, tin, s icon, nickel, germanium, manganese, magnesium, mercury, molybdenum, neodymium, galUum, boron, ruthenium, tungsten, titanium, zinc, and zirconium, including their oxides, nitrides, aUoys, chalcogenides, haUdes, sulfides, selenides, teUurides, phosphides, aUoys, and arsenides, etc., and mixtures thereof. The present procedure may also be appUed to conducting organic and other polymers, including polyanilines, polypyrroles, polythiophenes, polyacetylenes, and derivatives thereof, as well as polymers comprising such components as graphite fibers, carbon nanotubes, etc. The procedure may be appUed to electrodes made of any material that conducts electrons, including, for example, sodium electrodes that are operated in a non-aqueous and non-oxygen environment. The procedure may also be appUed to semiconductor electrodes, including doped and intrinsic. The procedure may also be appUed to boron nitride electrodes.
A glassy carbon disk working electrode was provided 502 (exemplary area = 0.459 cm2; however, the general procedure appUes to any size of electrode), and was poUshed 504 successively with 1.0 μm, 0.3 μm, and 0.05 μm alumina on Svelt poHshing cloths (Buehler). (Note that different poHshing cloths may be used when other electrodes are employed.) The electrode was then cleaned 506 by sonicating for about 5 minutes (range: about 1 to about 20 minutes) in 18 MΩ water to remove remaining alumina, soaking in concentrated nitric acid for about 2 minutes (approximate range: about 1 minute to about 10 minutes), and thoroughly rinsing with 18 MΩ water. With some metaUic and other electrodes, dilute nitric acid may be used in place of concentrated nitric acid. The electrode surface was then modified with either a Nafion® film or a magnetic microparticle/Nafion® composite. Nafion® films were prepared by pipetting an appropriate volume of about 5% by weight (w/w) Nafion® solution (the 5% by weight Nafion® polymer is mixed into a solution that is roughly 50% (v/v) 18 MΩ water and roughly 50% lower, straight chain aUphatic alcohols) onto the electrode surface. (Note that Nafion® polymer may also advantageously be mixed with other amounts of aqueous solvent, as weU as with other solvents, for example, with an alcohol, in order to change porosity properties of the resulting Nafion® composite.) The magnetic microparticle/Nafion® composites (containing sUoxyl coated magnetic microparticles) were prepared by pipetting an appropriate volume of composite stock solution onto the electrode surface in the presence of an external magnet 508, the shape of which affects the kinds of piUared composite structures that result, as is known in the art. The resulting Nafion® coated or Nafion®-magnetic composite coated electrode was then dried 510 by vacuum dessication or other drying method. Samarium cobalt composites were handled siirrUarly, except that the electrodes with composite and samarium cobalt were placed in an external magnet of a desired shape (again, shape of magnet being selected based on the desired shape of composite piUars)
45- after the firms were dry. The composite stock solution was prepared by adding appropriate fractions of 5% by weight (w/v) Nafion® solution and dry magnetic microparticles (sUoxyl coated) together. The fractions are calculated so that the dry composite film is composed of about 15% by volume as sUoxyl coated magnetic microparticles (range about 9% to about 19%; see above for notes on other det Us and other ranges that apply to other magnetic or metalUc materials) and about 85% by volume as Nafion®. The film thicknesses were about 54 μm. One exceptional study was performed on an electrode modified with one large samarium cobalt particle. These films were prepared by centering a roughly 1 mm diameter sUoxyl coated samarium cobalt particle on the electrode surface, and pipetting the above described 5% by weight (w/w) Nafion® solution over the particle/electrode. Thus, the samarium cobalt particle was suspended on the electrode surface with a Nafion® solution. The samarium cobalt particle was not buried inside the film because the particle was much thicker than the film.
Electrochemical Measurements. The electrochemical flux of Ru(bpy)3 +2 through the membrane layer to the electrode surface was studied using cycUc voltammetry. Nafion® film and magnetic microparticle/Nafion® composite modified working electrodes were equilibrated in 1.0 mM Ru(bpy)3 +2 and 0.1 M nitric acid for 4 hours before measurements were taken. The reference electrode was a saturated calomel electrode. The counter electrode was a large platinum gauze spot welded to platinum wire. Data were coUected and analyzed on a Pentium computer interfaced to a BioAnalytical Systems Model 100B/W Potentiostat. CycUc voltammetry was performed at scan rates ranging from 50 to 200 mV/s. In cycHc voltammetry, electrochemical flux is determined from the measured peak current (zϊ) for reversible electron transfers, and the measured peak current is a function of the extraction coefficient (K ) and the apparent diffusion coefficient (D^) of the redox probe in the composite or film.
Flux = ip I (nFA) (1)
ip = (2.69 x 105) «3/2 A Oφp 1/2 v eKC* (2) where n is the number of electrons transferred, F is Faraday's constant, A is the area of the electrode, v is the scan rate, € is the porosity of the film, and C* is the concentration of Ru(bpy)3 +2 in solution. The porosity of Nafion® films and composites consisting of one bead is approximately 1.0, and the porosity of the magnetic composites is about 0.85. Three repHcates of each experiment were performed.
Samarium Cobalt. Forming samarium cobalt/Nafion® composites has several engineering problems. Due to the high magnetic field environment of the samarium cobalt magnetic microparticles and the high density of the samarium particles, the samarium cobalt microparticles do not suspend in the Nafion® solution. This causes problems in determining the exact amount of magnetic micromaterial on the electrode surface. Therefore, flux enhancements cannot be quantified with the needed precision. A representative cycHc voltammogram of Ru(bpy)3 +2 in a samarium cobalt/Nafion® composite and in a Nafion® film is provided in Figure 6. Exact flux enhancement values cannot be determined because they require knowledge of porosities, which are unknown because of the inadequate suspension. However, it is evident that these systems do provide much larger flux enhancements than their magnetite counterparts. The peak currents for the silane coated samarium cobalt composites are seven to eight times larger than the Nafion® films. The difference in the peak potentials (ΔE ) are only 6 mV smaUer than the ΔE^'s for the Nafion® films. However, the peak potentials are asymmetrically shifted by 30 mV. The forward peak potential is shifted +30 mV with respect to Nafion®, and the backward peak potential is shifted -36 mV with respect to
Nafion®. Therefore, Ru(bpy)3 +2 is harder to electrolyze in the samarium cobalt composite than it is in Nafion®.
One Samarium Cobalt Particle. The single particle composite experiments are of interest because they show that only smaU amounts of particle/Nafion® interfaces are necessary to create a significant impact on electrochemical flux.
Because magnetic fields increase self-exchange rates by several orders of magnitude, smaU volumes of magnetic particles can have measurable effects on electrochemical flux. The cycUc voltammetry of Ru(bpy)3 +2 in a single samarium cobalt particle/Nafion® composite and a Nafion® film is shown in Figure 7. The roughly 1 mm diameter (the upper limit is roughly 2 mm in diameter) samarium cobalt particle/Nafion® composite shows lower flux enhancements for Ru(bpy)3 +2 than a regular composite. This is expected because there is Httle bead/Nafion® interface, and because a lower volume percent of the film is in the presence of a high magnetic field. The differences in the peak potentials (Δ-E^) are approximately the same as the Δ.-ΞJS for the Nafion® films. The peak potentials are asymmetricaUy shifted by only 15 mN because there is a smaUer average magnetic field at the electrode surface. The forward peak potential is shifted +5 mV with respect to Nafion®, and the backward peak potential is shifted -5 mV with respect to Nafion®.
Magnetite. The siloxyl coated magnetite composites are similar in morphology to the Polyscience paramagnetic microparticle composite, except the Polyscience paramagnetic icroparticle composites have an orange tint to them, whereas the sUoxyl coated magnetite composites are dark black. SUoxyl coated magnetite microparticles comprise black microparticles, and Polyscience paramagnetic microparticles comprise dark orange/brown microparticles. The orange brown coloration is due in part to the thick polystyrene shroud around the Polyscience paramagnetic microparticle, and in part to degradation of magnetite to other forms of iron oxide.
The siloxyl coated magnetite/Nafion® composites show simHar enhancements in electrochemical flux as probed by cycUc voltammetry. This can be seen from the cycHc voltammograms of Ru(bpy)3 +2 in a siloxyl coated magnetite/Nafion® composite and in a Nafion® film, as is shown in Figure 8. The differences in the peak potentials (ΔE^) are 5 mN larger than the AEp s for the afion® films. The forward peak potential is shifted 48 mN with respect to Nafion®, and the backward peak potential is shifted -33 mN with respect to Nafion®.
Nickel. SUoxyl coated nickel microparticles form composites that look similar to the composites formed from sUoxyl coated magnetite microparticles. The main functional difference between the two composites is that nickel is a weaker magnetic material. Nickel microparticles are superparamagnetic, so they only sustain a magnetic field in the presence of an external magnetic field. Therefore, the cycUc voltammogram of the sUoxyl coated nickel microparticle/Nafion® composite shown in Figure 9 is in the presence of a 0.2 T external
48- cyUndrical magnet. Because nickel microparticles are less magnetic than magnetite, the flux enhancements for sUoxyl coated nickel microparticle/Nafion® composites are less than for sUoxyl coated magnetite microparticles/Nafion® composites. The difference in the peak potentials (ΔE^) are 30 mV larger than the ΔE^'s for the Nafion® films. The forward peak potential is shifted 58 mV with respect to Nafion® and the backward peak potential is shifted
-28 mV with respect to Nafion®.
Summary Data. The results for the cycUc voltammetry are summarized in Table 2. AU of the data in Table 2 are adjusted for porosity, except the sUoxyl coated samarium cobalt miUiparticle and particle data. The clumping of samarium cobalt microparticles because of magnetic attraction, which forms miUiparticles, does not aUow determination of film porosity.
The porosities of the samarium cobalt miUiparticle composites are approximately 1.0 because a particle consumes only a smaU volume of the polymer composite. The sUoxyl coated magnetic micromaterials appear to be as stable as the Polysciences microspheres. The sUane coated magnetite microparticles, prepared as described herein, show the same flux enhancement as observed for the Polysciences microspheres, within errors of measurement.
However, the flux enhancements for sUoxyl coated magnetite are more reproducible than the flux enhancements for Polysciences microparticles.
Table 2. Flux Enhancements and Peak Shifts for SUoxyl Coated
Microparticle/Nafion Composites
Figure imgf000021_0001
The sUane coated nickel composites produce much smaUer flux enhancements than the magnetite composites because " nickel is a much weaker magnetic material. The nickel microparticles would not be commerciaUy useful in many technological appUcations because the flux enhancements are so smaU, and they require the presence of an external magnetic field. However, they might constitute acceptable material for a flux throttle or switch, as can iron and cobalt microparticles. The sUane coated samarium cobalt composites have exceUent magnetic benefits even if they have engineering difficulties. The large flux enhancement seen in Figure 5 Ulustrates the usefulness of this magnetic material. The best illustration of the power of the sUoxyl coated samarium cobalt composites is the single particle experiment, results of which are shown in Figure 6. The flux enhancements shown in Table 2 increase with magnetic field strength. This is expected because the apparent diffusion coefficient increases Hnearly with magnetic field in the interface. The peak shifts vary from composite to composite because of the interplay between the magnetic field effects on apparent diffusion coefficients and on heterogeneous electron transfer. Large magnetic fields dramaticaUy increase apparent diffusion coefficients, which generaUy yield larger .Ep values. Large magnetic field effects on heterogeneous electron transfer reactions increase heterogenous electron transfer rates for paramagnetic species reacting to diamagnetic species, but there is no increase in rate for diamagnetic species reacting to paramagnetic species. The interplay between these two magnetic field effects cause the large variations in peak shifts seen in Table 2. The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be reacUly appUed to other types of apparatuses, coating methodologies, and sUoxyl coated particle uses. The description of the present invention is intended to be iUustrative, and not to Umit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function, and not only structural equivalents but also equivalent structures. For example, additional uses of sUoxyl coated magnetic microparticles and sUoxyl coated magnetic miUiparticles on kinds of electrodes not specificaUy described herein faU within the intended scope of the present invention. Also, sUoxyl coating of metaUic particles not specificaUy disclosed herein faU within the intended scope of the present invention. In addition, uses of sUoxyl coated magnetic microparticles not specificaUy described herein faU within the intended scope of the present invention when they enhance or decrease a magneticaUy susceptible process of any sort. Further more, magnetic and metalUc materials not specifically Usted herein are intended to be encompassed by the scope of the present invention.

Claims

WHAT IS CLAIMED IS:
1. SUoxyl coated metaUic particles, comprising: metaUic particles with at least one covalently bound sUoxyl coating.
2. The siloxyl coated metaUic particles according to claim 1, wherein the at least one covalently bound sUoxyl coating is cross Unked.
3. SUoxyl coated metalUc particles, comprising: metalUc particles with at least one cross Unked and covalently bound siloxyl coating.
4. A method of making siloxyl coated and cross Unked metalUc particles, comprising the steps of: rrrbdng siloxyl coated metaUic particles with a cross Unking solution to yield a sUoxyl coated metalUc particle-cross Unking solution mixture; creating a suspension of said sUoxyl coated metalUc particle-cross Unking solution mixture for a period of time to yield siloxyl coated and cross Unked metaUic particles; and separating said sUoxyl coated and cross Unked metaUic particles from said cross Unking solution.
5. The method of making sUane coated and cross Unked metaUic particles according to claim 4, further comprising the step of: rinsing said sUane coated and cross Hnked metalUc particles to yield purified silane coated and cross Hnked metaUic particles.
6. The method of making silane coated and cross Unked metalUc particles according to claim 4, wherein the coating procedure is conducted at about room temperature, and said period of time is about 4 hours.
7. The method of making sUane coated and cross Unked metaUic particles according to claim 4, wherein said metalUc particles comprise metaUic microparticles.
8. The method of making silane coated and cross Unked metaUic particles according to claim 7, wherein said metalUc microparticles comprise a range of diameters from about 2 μm to about 10 μm.
9. The method of making silane coated and cross Hnked metaUic particles according to claim 7, wherein said metaUic microparticles comprise a range of diameters from about 0.1 μm to about 20 μm.
10. The method of making sUane coated and cross Hnked metaUic particles according to claim 7, wherein said metalUc microparticles comprise magnetic microparticles.
11. The method of making sUane coated and cross linked metaUic particles according to claim 10, wherein said magnetic microparticles comprise at least one of an iron oxide, a samarium cobalt, nickel, and neodymium iron boron.
12. The method of making sUane coated and cross Unked metaUic particles according to claim 4, wherein said cross Unking solution comprises at least one of ethylene glycol diglycidyl ether, ethylene glycol dimethacrylate, 2-ethylhexyl glycidyl ether, ethylene glycol bis [pentakis (glycidyl aUyl ether)] ether, 1,4-butanediol glycidyl ether, 4-tert-butyl phenyl glycidyl ether, N,N'-bis (acryloyl) cystamine, nitrilotriacetic acid tri (N-succinimidyl) ester, and 4- azidophenyl isothiocyanate.
13. The method of making sUane coated and cross Unked metaUic particles according to claim 4, wherein said cross Unking solution comprises about 50/50 (vol/vol) of a cross Unking agent and a solvent in which said cross Unking agent is soluble.
14. The method of making sUane coated and cross Hnked metaUic particles according to claim 13, wherein said cross Unking agent comprises at least one of ethylene glycol diglycidyl ether, ethylene glycol dknethacrylate, 2-ethylhexyl glycidyl ether, ethylene glycol bis [pentakis (glycidyl allyl ether)] ether, 1,4-butanediol glycidyl ether, 4-tert-butyl phenyl glycidyl ether, N,N'-bis (acryloyl) cystamine, nitrUotriacetic acid tri (N-succinimidyl) ester, and 4-azidophenyl isothiocyanate.
16. The method of making sUane coated and cross Unked metaUic particles according to claim 14, wherein said solvent comprises water.
17. A method of making sUoxyl coated metaUic particles, comprising the steps of: mixing metaUic particles with a sUane solution to yield a metaUic particle-sUane solution mixture; creating a suspension of said metaUic particle-silane solution mixture for a first period of time to yield sUoxyl coated metaUic particles; and separating said siloxyl coated metaUic particles from said silane solution.
18. A method of making siloxyl coated metaUic particles, further comprising the step of: rinsing said sUoxyl coated metaUic particles with an organic solvent to yield purified sUoxyl coated metaUic particles.
19. The method of making sUoxyl coated metaUic particles according to claim 17, further comprising the step of drying said purified sUoxyl coated metaUic particles.
20. A method of making sUoxyl coated and cross Hnked metaUic particles, comprising the steps of: mixing dried and purified sUoxyl coated metaUic particles, made by the method of claim 18, with a cross Unking solution to yield a sUoxyl coated metalUc particle-cross Unking solution mixture; creating a suspension of said sUoxyl coated metaUic particle-cross Unking solution mixture for a second period of time to yield sUoxyl coated and cross Unked metaUic particles; and separating said sUoxyl coated and cross Unked metalUc particles from said cross Unking solution.
21. The method of making sUoxyl coated and cross Hnked metaUic particles according to method of claim 20, further comprising the step of: rinsing said sUoxyl coated and cross Hnked metaUic particles to yield purified sUoxyl coated and cross Unked metaUic particles.
22. The method of making siloxyl coated and cross Hnked metaUic particles according to claim 20, wherein the coating procedure is conducted at about room temperature, and said first and second periods of time each independently equal about 4 hours.
23. The method of making sUoxyl coated metalUc particles according to claim 17, wherein said sUane solution comprises at least one X-Cv-trialkoxysUane, wherein
X comprises a group reactive toward a cross Unking agent, comprising one of an amino, an amide, a thiol, an aldehyde, a nitrUe, a sulfonyl, an alcohol, a carbonyl, a carboxy, a chloro, an alkoxy, a bromo, an iodo, a sulfonyl, a carbonyl, and a methacryl; x equals 1 to about 20; Cx is a Hnear or branched carbon chain that is saturated or unsaturated, and that also can comprise a cycUc group with the proviso that said cycHc group must be separated from the trialkoxysUane moiety by a carbon chain that is at least 2 carbons in length; and trialkoxysUane comprises three alkoxy groups covalently attached to a sUane group, and wherein the three alkoxy groups independently can be methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, or phenoxy, wherein the phenoxy may be substituted.
24. The method of making siloxyl coated metaUic particles according to claim 23, wherein the at least one X-Cλ,-trialkoxysUane comprises 3-aminopropyltrimethoxysilane.
25. The method of making sUoxyl coated metaUic particles according to claim 17, wherein said sUane solution comprises at least one organic solvent.
26. The method of making sUoxyl coated metaUic particles according to claim 25, wherein said organic solvent comprises toluene.
27. The method of making siloxyl coated metaUic particles according to claim 17, wherein said metalUc particles comprise metaUic microparticles.
28. The method of making sUoxyl coated metaUic particles according to claim 27, wherein said metaUic microparticles comprise a range of diameters from about 2 μm to about 10 μm.
29. The method of making sUoxyl coated metaUic particles according to claim 27, wherein said metaUic microparticles comprise a range of diameters from about 0.1 μm to about 20 μm.
30. The method of making sUoxyl coated metaUic particles according to claim 17, wherein said metaUic particles comprise miUiparticles comprising a range of diameters from about 20 μm to about 2 mm.
31. The method of making sUoxyl coated metaUic particles according to claim 27, wherein said metaUic microparticles comprise magnetic microparticles.
32. The method of making siloxyl coated metaUic particles according to claim 31, wherein said magnetic microparticles comprise at least one of an iron oxide, a samarium cobalt, nickel, and a neodymium iron boron.
33. The method of malting sUoxyl coated and cross Hnked metaUic particles according to claim 20, wherein said cross Unking solution comprises at least one of ethylene glycol diglycidyl ether, ethylene glycol dimethacrylate, 2-ethylhexyl glycidyl ether, ethylene glycol bis [pentakis (glycidyl aUyl ether)] ether, 1,4-butanediol glycidyl ether, 4-tert-butyl phenyl glycidyl ether, N,N'-bis (acryloyl) cystamine, nitrUotriacetic acid tri (N-succin-midyl) ester, and 4-azidophenyl isothiocyanate.
34. The method of making sUoxyl coated and cross Hnked metalUc particles according to claim 20, wherein said cross Unking solution comprises about 50/50 (vol/vol) of a cross Unking agent and a solvent in which said cross Uniting agent is soluble.
35. The method of making siloxyl coated and cross Unked metaUic particles according to claim 34, wherein said cross Unking agent comprises at least one of ethylene glycol diglycidyl ether, ethylene glycol dimethacrylate, 2-ethylhexyl glycidyl ether, ethylene glycol bis [pentakis (glycidyl aUyl ether)] ether, 1,4-butanediol glycidyl ether, 4-tert-butyl phenyl glycidyl ether, N,N'-bis (acryloyl) cystamine, nitrUotriacetic acid tri (N-succinimidyl) ester, and 4- azidophenyl isothiocyanate.
36. The method of making sUoxyl coated and cross Unked metaUic particles according to claim 34, wherein said solvent comprises water.
37. A method of providing a pluraHty of sUoxyl coatings on metalUc particles, comprising the steps of: anneaUng metaUic particles, having a single sUoxyl coating, in a nitrogen environment at a temperature less than the Curie temperature; and repeating the steps of claim 16 at least one time to yield metalUc particles having at least two sUoxyl coatings.
38. The method of providing a pluraHty of siloxyl coatings on metaUic particles according to claim 37, wherein anneaUng is effected by heating to about 450°C (+ about 30°C) for about an hour.
39. A method of sUoxyl coating metaUic particles, comprising the steps of: mixing metalUc particles with a sUane solution to yield a metalUc particle-sUane solution mixture; creating a suspension of said metallic particle-sUane solution mixture for a first period of time to yield siloxyl coated metaUic particles; separating said siloxyl coated metaUic particles from said silane solution; rinsing said siloxyl coated metaUic particles with an organic solvent to yield purified sUoxyl coated metalUc particles; drying said purified siloxyl coated metaUic particles; mixing said dried and purified sUoxyl coated metaUic particles with a cross
Unking solution to yield a sUoxyl coated metaUic particle-cross Unking solution mixture; creating a suspension of said sUoxyl coated particle-cross Unking solution mixture for a second period of time to yield sUoxyl coated and cross Hnked metaUic particles; and separating said sUoxyl coated and cross Hnked metalUc particles from said cross
Unking solution.
40. The method of sUoxyl coating metaUic particles according to claim 39, further comprising the step of: rinsing said sUoxyl coated and cross Hnked metalUc particles to yield purified sUoxyl coated and cross Unked metaUic particles.
41. The method of sUoxyl coating metaUic particles according to claim 40, further comprising the step of: drying said purified sUoxyl coated and cross Hnked metalUc particles.
42. The method of sUoxyl coating metaUic particles according to claim 39, wherein the coating procedure is conducted at about room temperature, and said first and second periods of time each independently equal about 4 hours.
43. The method of siloxyl coating metalUc particles according to claim 39, wherein said sUane solution comprises at least one X-C^-trialkoxysUane, wherein
X comprises a group reactive toward a cross Unking agent, comprising one of amino, amide, thiol, aldehyde, nitrUe, sulfonyl, alcohol, carbonyl, carboxy, chloro, an alkoxy, a bromo, an iodo, a sulfonyl, a carbonyl, and a methacryl; x equals 1 to about 20;
Cxis a Hnear or branched carbon chain that is saturated or unsaturated, and that also can comprise a cycHc group with the proviso that said cycHc group must be separated from the trialkoxysUane moiety by a carbon chain that is at least 2 carbons in length; and trialkoxysUane comprises three alkoxy groups covalently attached to a sUane group, and wherein the three alkoxy groups independently can be methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, or phenoxy, wherein the phenoxy may be substituted.
44. The method of sUoxyl coating metaUic particles according to claim 43, wherein the at least one X-C^-triaikoxysUane comprises 3-aminopropyltrimethoxysUane.
45. The method of sUoxyl coating metaUic particles according to claim 39, wherein said organic solvent comprises at least one aromatic organic solvent.
46. The method of siloxyl coating metaUic particles according to claim 45, wherein said aromatic organic solvent comprises toluene.
47. The method of sUoxyl coating metaUic particles according to claim 39, wherein said metaUic particles comprise metaUic microparticles.
48. The method of sUoxyl coating metaUic particles according to claim 47, wherein said metalUc microparticles comprise a range of diameters from about 2 μ to about 10 μm.
49. The method of sUoxyl coating metaUic particles according to claim 47, wherein said metalUc microparticles comprise a range of diameters from about 0.1 μm to about 20 μm.
50. The method of sUoxyl coating metalUc particles according to claim 39, wherein said metalUc particles comprise mUHparticles comprising a range of diameters from about 20 μm to about 2 mm.
51. The method of sUoxyl coating metaUic particles according to claim 47, wherein said metalUc microparticles comprise magnetic microparticles.
52. The method of sUoxyl coating metaUic particles according to claim 51, wherein said magnetic microparticles comprise at least one of an iron oxide, a samarium cobalt, nickel, and a neodymium iron boron.
53. The method of sUoxyl coating metaUic particles according to claim 39, wherein said cross Unking solution comprises at least one of ethylene glycol diglycidyl ether, ethylene glycol dirnethacrylate, 2-ethylhexyl glycidyl ether, ethylene glycol bis [pentakis (glycidyl aUyl ether)] ether, 1,4-butanediol glycidyl ether, 4-tert-butyl phenyl glycidyl ether, N,N'-bis (acryloyl) cystamine, nitrUotriacetic acid tri (N-succinimidyl) ester, and 4-azidophenyl isothiocyanate.
54. The method of sUoxyl coating metaUic particles according to claim 39, wherein said cross Unking solution comprises about 50/50 (vol/vol) of a cross Unking agent and a solvent in which said cross Unking agent is soluble.
55. The method of siloxyl coating metaUic particles according to claim 54, wherein said cross Unking agent comprises at least one of ethylene glycol diglycidyl ether, ethylene glycol dimethacrylate, 2-ethylhexyl glycidyl ether, ethylene glycol bis [pentakis (glycidyl aUyl ether)] ether, 1,4-butanediol glycidyl ether, 4-tert-butyl phenyl glycidyl ether, N,N'-bis (acryloyl) cystamine, nitrUotriacetic acid tri (N-succinimidyl) ester, and 4-azidophenyl isothiocyanate.
56. The method of sUoxyl coating metaUic particles according to claim 54, wherein said solvent comprises water.
57. A method of providing a pluraHty of sUoxyl coatings on metalUc particles, comprising the steps of: anneaUng metalUc particles, having a single siloxyl coating, in a nitrogen environment at a temperature less than the Curie temperature; and repeating the steps of claim 39 at least one time to yield metaUic particles having at least two sUoxyl coatings.
58. The method of sUoxyl coating metaUic particles of claim 57, wherein anneaUng is effected by heating to about 450°C (± about 30°C) for about an hour.
59. A method of making magneticaUy modified electrodes comprising sUoxyl coated magnetic particles, comprising the steps of: providing an electrode, comprising at least one surface; poHshing the at least one surface of the electrode; cleaning the at least one surface of the electrode; and applying to the at least one surface a coating comprising sUoxyl coated magnetic particles.
60. The method of making magneticaUy modified electrodes comprising sUoxyl coated magnetic particles according to claim 59, further comprising the step of: drying the electrode with at least one coated surface.
61. The method of making magneticaUy modified electrodes comprising siloxyl coated magnetic particles according to claim 59, wherein the siloxyl coating of the sUoxyl coated magnetic particles is cross Hnked.
62. A method of making magneticaUy modified electrodes comprising siloxyl coated magnetic particles, comprising the steps of: providing an electrode, comprising at least one surface; poHshing the at least one surface of the electrode; cleaning the at least one surface of the electrode; and applying to the at least one surface at least one coating comprising magnetic particles that are coated with at least one siloxyl coating.
63. The method of making magneticaUy modified electrodes comprising siloxyl coated magnetic particles according to claim 62, further comprising the step of: drying the electrode with at least one coated surface.
64. The method of making magneticaUy modified electrodes comprising sUoxyl coated magnetic particles according to claim 62, wherein at least one coating of the at least one sUoxyl particle coating is cross Hnked.
65. The method of making magneticaUy modified electrodes comprising sUoxyl coated magnetic particles according to claim 62, wherein at least one of the at least one surface coating comprises magnetic particles comprising at least one cross Hnked siloxyl particle coating.
66. A magnetically modified electrode with sUoxyl coated magnetic particles, comprising: an electrode, with a surface having at least one coating that includes sUoxyl coated magnetic particles.
67. The magneticaUy modified electrode with sUoxyl coated magnetic particles according to claim 66, wherein some of the siloxyl coated magnetic particles are cross Hnked.
68. A magnetically modified fuel cell with altered function, comprising: at least one electrode, each respective electrode comprising at least one surface with at least one coating thereon, wherein at least one of the at least one surface coatings comprises sUoxyl coated magnetic particles.
69. The magneticaUy modified fuel ceU with altered function according to claim 68, wherein at least one siloxyl particle coating of the sUoxyl coated magnetic particles is cross Hnked.
70. A magneticaUy modified fuel ceU with altered oxidation rates of organic fuels, comprising: at least one electrode, each respective electrode comprising at least one surface with at least one coating thereon, wherein at least one of the at least one surface coatings comprises sUoxyl coated magnetic particles.
71. The magneticaUy modified fuel ceU with altered oxidation rates of organic fuels according to claim 70, wherein at least one sUoxyl particle coating of the sUoxyl coated magnetic particles is cross Hnked.
72. A magnetically modified electrolytic ceU with altered function, comprising: at least one electrode, each respective electrode comprising at least one surface with at least one coating thereon, wherein at least one of the at least one surface coatings comprises sUoxyl coated magnetic particles.
73. The magneticaUy modified electrolytic ceU with altered function according to claim 72, wherein at least one sUoxyl particle coating of the sUoxyl coated magnetic particles is cross Unked.
74. A magneticaUy modified battery with altered function, comprising: at least one electrode, each respective electrode comprising at least one surface with at least one coating thereon, wherein at least one of the at least one surface coatings comprises sUoxyl coated magnetic particles.
75. The magneticaUy modified battery with altered function according to claim 74, wherein at least one sUoxyl particle coating of the sUoxyl coated magnetic particles is cross Hnked.
76. A magneticaUy modified flux switch with altered function, comprising: at least one electrode, each respective electrode comprising at least one surface with at least one coating thereon, wherein at least one of the at least one surface coatings comprises sUoxyl coated magnetic particles.
77. The magneticaUy modified flux switch with altered function according to claim 76, wherein at least one sUoxyl particle coating of the sUoxyl coated magnetic particles is cross Unked.
78. A paramagneticaUy modified flux switch with altered function, comprising: at least one electrode, each respective electrode comprising at least one surface with at least one coating thereon, wherein at least one of the at least one surface coatings comprises sUoxyl coated magnetic particles.
79. The paramagneticaUy modified flux switch with altered function according to claim 78, wherein at least one sUoxyl particle coating of the sUoxyl coated magnetic particles is cross Hnked.
80. A magneticaUy modified semiconductor electrode with sUoxyl coated magnetic particles, comprising: at least one surface comprising a semiconductor material, wherein the at least one surface comprises at least one coating that comprises siloxyl coated magnetic particles.
81. The magnetically modified seimiconductor electrode with sUoxyl coated magnetic particles according to claim 80, wherein at least one siloxyl particle coating of the siloxyl coated magnetic particles is cross Hnked.
82. The magneticaUy modified semiconductor electrode with sUoxyl coated magnetic particles according to claim 81, wherein the semiconductor electrode comprises a component of a photoelectrochemical ceU.
83. The magneticaUy modified semiconductor electrode with sUoxyl coated magnetic particles according to claim 81, wherein the semiconductor electrode comprises a component of a solar ceU.
84. A method of altering electrolysis of a fuel ceU by applying sUoxyl coated magnetic particles to at least one surface of at least one electrode thereof, comprising the steps of: poHshing the at least one surface of the at least one electrode; cleaning the at least one surface of the at least one electrode; and applying to the at least one surface a coating comprising sUoxyl coated magnetic particles.
85. The method of altering electrolysis of a fuel ceU by applying siloxyl coated magnetic particles to at least one surface of at least one electrode thereof according to claim 84, further comprising the step of: drying the electrode with at least one coated surface.
86. The method of altering electrolysis of a fuel ceU according to claim 84, wherein altering electrolysis comprises one of enhancing electrolysis and cUminishing electrolysis.
87. A method of altering electrolysis of an electrolytic cell by applying siloxyl coated magnetic particles to at least one surface of at least one electrode thereof, comprising the steps of: poHshing the at least one surface of the at least one electrode; cleaning the at least one surface of the at least one electrode; and applying to the at least one surface a coating comprising sUoxyl coated magnetic particles.
88. The method of altering electrolysis of an electrolytic ceU by applying sUoxyl coated magnetic particles to at least one surface of at least one electrode thereof according to claim 87, further comprising the step of: drying the electrode with at least one coated surface.
89. The method of altering electrolysis of an electrolytic ceU according to claim 84, wherein altering electrolysis comprises one of enhancing electrolysis and diminishing electrolysis.
90. A method of altering electrolysis at an electrode surface by applying siloxyl coated magnetic particles the electrode surface, comprising the steps of: poHshing the electrode surface; cleaning the electrode surface; and applying to the electrode surface a coating comprising sUoxyl coated magnetic particles.
91. The method of altering electrolysis at an electrode surface by applying siloxyl coated magnetic particles to the electrode surface according to claim 90, further comprising the step of: drying the electrode surface.
92. The method of altering electrolysis at an electrode surface according to claim 90, wherein altering electrolysis comprises one of enhancing electrolysis and cLiminishing electrolysis.
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