8385 results about "Graphite oxide" patented technology

A modified graphite oxide material contains a thermally exfoliated graphite oxide with a surface area of from about 300 m²/g to 2600 m²/g, wherein the thermally exfoliated graphite oxide displays no signature of the original graphite and/or graphite oxide, as determined by X-ray diffraction.

The invention relates to a method for preparing graphene compounds and graphene oxide compounds with high efficiency, relating to the method for preparing the graphene compounds and the graphene oxide compounds. The invention solves the problems of easy composition of graphene or graphene oxide per se and many process steps, higher cost and difficult dispersedness for preparing the graphene compounds and the graphene oxide compounds by the traditional method at the same time. The invention adopts a mechanical stripping method to obtain the graphene compounds and the graphene oxide compounds. In the invention, an automatic machine is utilized, solid particles are used for assisting stripping, the contact area and the stripping number of the stripping process are greatly increased, and carbon material powder experiences a lot of stripping processes through the action of shear and impact, thereby obviously improving the stripping efficiency and achieving the purpose of uniform dispersedness to the composites. The method is suitable for industrial mass production of the graphene compounds and the graphene oxide compounds.

The invention relates to a preparation method of a polymer/graphene composite material through in situ reduction, which is characterized by comprising the following steps: adopting ultrasonic wave or grinding to evenly disperse the graphite oxide prepared by a Hummers method into polymer dispersion; introducing reducing agent into the polymer dispersion for in situ reduction, enabling the graphite oxide to be reduced into the grapheme so as to obtain stable polymer/graphene composite emulsion; carrying out demulsification, agglomeration and drying to obtain the composite polymer/grapheme composite master batch; adding the dried polymer/grapheme composite master batch and various assistants into the polymeric matrix according to a certain ratio; and carrying out double-roller mixing, vulcanization, melt extrusion or injection molding to obtain the polymer/graphene composite material with excellent physical and mechanical properties.

The present invention provides a method of exfoliating a layered material (e.g., graphite and graphite oxide) to produce nano-scaled platelets having a thickness smaller than 100 nm, typically smaller than 10 nm. The method comprises (a) dispersing particles of graphite, graphite oxide, or a non-graphite laminar compound in a liquid medium containing therein a surfactant or dispersing agent to obtain a stable suspension or slurry; and (b) exposing the suspension or slurry to ultrasonic waves at an energy level for a sufficient length of time to produce separated nano-scaled platelets. The nano-scaled platelets are candidate reinforcement fillers for polymer nanocomposites. Nano-scaled graphene platelets are much lower-cost alternatives to carbon nano-tubes or carbon nano-fibers.

The invention provides a method for preparing graphene or graphene oxide by using high-efficiency and low-cost mechanical stripping and relates to a preparation method of the graphene or the graphene oxide, solving the problems that the traditional micro-mechanical stripping method has low efficiency and can not be used for large-batch production. The method comprises the following step of separating carbon materials by utilizing solid particles and a liquid working medium (or gas working medium) and adopting mechanical stripping to obtain the graphene or the graphene oxide, wherein the carbon materials comprise graphite powder, expanded graphite, expandable graphite or graphite powder oxide. By using automatic machinery and using a great deal of solid particles for assisting stripping processes, the invention greatly increases the contact areas and the stripping times of the stripping processes, the carbon materials are subject to a great amount of stripping processes in a short time through the shearing and impacting functions of the solid particles on the carbon materials, and thereby the method obviously improves the stripping efficiency, has low cost and is suitable for the industrial and large-batch production of the graphene or the graphene oxide.

The invention discloses a preparation method of a graphene reinforced metal-matrix composite, which comprises the following steps of: firstly, dispersing the graphene oxide on the surface of the flaky metal powder; and then obtaining the graphene/metal composite powder through the reducing treatment; and at last, carrying out densification treatment by adopting a powder metallurgic technology to obtain the compact graphene reinforced metal-matrix composite. The flaky metal powder has the plane two-dimensional form, is inclined to the directional piling to form a laminated structure, and is helpful for inducing the graphene orientation distribution and giving play to the reinforcing effect. The preparation method disclosed by the invention is simple and feasible, is capable of regulating the graphene content and is suitable for preparing the massive composite.

The present invention provides a process for producing nano graphene platelets (NGPs) that are dispersible and conducting. The process comprises: (a) preparing a graphite intercalation compound (GIC) or graphite oxide (GO) from a laminar graphite material; (b) exposing the GIC or GO to a first temperature for a first period of time to obtain exfoliated graphite; and (c) exposing the exfoliated graphite to a second temperature in a protective atmosphere for a second period of time to obtain the desired dispersible nano graphene platelet with an oxygen content no greater than 25% by weight, preferably below 20% by weight, further preferably between 5% and 20% by weight. Conductive NGPs can find applications in transparent electrodes for solar cells or flat panel displays, additives for battery and supercapacitor electrodes, conductive nanocomposite for electromagnetic wave interference (EMI) shielding and static charge dissipation, etc.

A functionalised graphene oxide and a method of making a functionalised graphene oxide comprising: (i) oxidizing graphite to form graphite oxide wherein the graphene sheets which make up the graphite independently of each other have a basal plane fraction of carbon atoms in the sp²-hybridised state between 0.1 and 0.9, wherein the remainder fraction comprises sp³-hybridised carbon atoms which are bonded to oxygen groups selected from hydroxyl and/or epoxy and/or carboxylic acid; and (ii) exfoliating and in-situ functionalizing the graphite oxide surface with one or more functional groups such that functionalisation of the surface is effected at a concentration greater than one functional group per 100 carbon atoms and less than one functional group per six carbon atoms. The functionalised graphene oxide is dispersible at high concentrations in appropriate solvents without aggregating or precipitating over extended periods at room temperature.

The invention discloses a silicon graphene composite anode material of a lithium ion battery and a preparation method of the silicon graphene composite anode material. The material consists of the following components in percentage by weight: 10 to 99 percent of silicon powder with the particle size of between 20 nanometers and 5 micrometers, 1 to 90 percent of graphene and 0 to 40 percent of amorphous carbon, wherein the graphene forms a three-dimensional conducting network with an internal cavity, and wraps the silicon powder in the internal cavity to form spherical or sphere-like composite particles with the particle size of between 500 nanometers and 15 micrometers. The preparation method of the material comprises the following steps of: uniformly dispersing the silicon powder and graphene oxide in a solvent; and performing spray drying, reducing, and cladding by using the amorphous carbon. Compared with the prior art, the invention has the advantages that: the material has high capacity and high cycle performance and is subjected to a constant-current charge-discharge test at the current density of 200mA/g, the reversible capacity of the material after 30-times circulation is still 1502mA/g, and the capacity retention rate of the material is up to 98 percent; and the preparation method is simple and practicable, high in yield and suitable for mass industrial production.

A polymer composition, containing a polymer matrix which contains an elastomer; and a functional graphene which displays no signature of graphite and/or graphite oxide, as determined by X-ray diffraction, exhibits excellent strength, toughness, modulus, thermal stability and electrical conductivity.

The present invention relates a graphene/metal oxide hybrid aerogel, a preparation method and applications thereof, and belongs to the field of nanometer material applications. The hybrid aerogel comprises a graphene network and a metal oxide network, wherein the two networks are mutually wound to form a hybrid aerogel, and the metal oxide network is further a crystalline state. The hybrid aerogel preparation comprises: preparing a graphene oxide organic solution, adding a soluble metal salt and an epoxide to obtain a uniform non-flowing hybrid wet gel, and carrying out drying and charring to obtain the graphene/metal oxide hybrid aerogel. The hybrid aerogel can be used as an energy storage material, an electromagnetic shielding material, a biological enzyme catalysis carrier and a CO2 absorption material, and has wide applications.

The invention relates to a method for preparing a graphene loaded ferroferric oxide magnetic nanometer particle composite material. The method comprises the following steps of: (1) dispersing graphite oxide into deionized water, pouring into a vessel after ultrasonic and centrifuging, putting the vessel into an oil-bath pan, adding hydrazine hydrate and an anionic surfactant for heating, condensing and refluxing, and cooling and drying to obtain modified graphene; and (2) dispersing the graphene into aqueous solution, and ultrasonically stirring and centrifuging to obtain modified graphene dispersion liquid; and weighing a soluble trivalent ferric salt and divalent ferric salt, dissolving the salt into the deionized water, introducing nitrogen, pouring into the modified graphene dispersion liquid, dripping ammonia after uniform ultrasonic stirring, heating for reaction, washing and collecting a product, and drying the product. The method is simple and easy for industrial production; and the prepared composite material has the advantages of pure crystal phase, uniform distribution and excellent electrocatalytic activity.

The invention relates to a preparation method of a graphene heat conducting membrane. The method comprises the following steps: filtrating or coating graphene oxide dispersed in a solvent to obtain a graphene oxide membrane; then, reducing the graphene oxide membrane at a high temperature to obtain the graphene heat conducting membrane. The preparation method of the graphene heat conducting membrane, provided by the invention, is simple in technique, simple in operation and easy in control on conditions, and the graphene heat conducting membrane provided by the invention is controllable in shape, size and thickness and relatively high in heat conductivity.

The invention discloses a graphene-based barrier composite material, which has high barrier and mechanical performance and is prepared by using grapheme sheets which are two-dimension nano materials as an intensifier and uniformly dispersing the grapheme sheets in a polyolefin polymer by chemical crosslinking. The preparation method of the barrier composite material comprises: 1, functionally modifying the surface of the graphene oxide by using coupling agent to graft active functional groups on the surface of the graphene oxide, and reducing the modified graphene oxide into grapheme; and 2, uniformly dispersing the modified graphene into solution of the polyolefin to perform crosslinking under the action of an initiator to obtain the nano composite material. In the invention, the raw material is low in cost and readily available; the operation is easy, the process is simple, the repeatability is high, the graphene can well disperse in the polyolefin, and the prepared graphene-based barrier composite material has high polar and nonpolar solvent barrier performance and is obviously improved in tensile strength and fracture toughness.

Compositions comprising crosslinked graphene sheets and/or graphite oxide and having essentially no polymer binder and methods of making crosslinked graphene sheets and/or graphite oxide. The compositions can be made by crosslinking coatings comprising graphene sheets and/or graphite oxide.

The invention discloses a grapheme/silicon composite material for a lithium ion battery cathode material and a preparation method thereof, belonging to the fields of electrochemistry and new energy materials. The method comprises the following steps of: using graphite as a raw material; oxidizing the graphite into oxidized graphite by adopting oxidants of concentrated sulfuric acid and potassium permanganate; then, ultrasonically stripping the oxidized graphite to prepare oxidized graphene; mixing oxidized graphene in different proportions with nano silicon powder; ultrasonically dispersing, filtering or directly drying into a cake/film; and roasting under a reduction atmosphere to prepare self-support graphene/silicon composite film materials in different proportions. Proved by electrochemistry tests, the graphene/silicon composite film material prepared by the method has higher specific capacity and cycle stability, simple preparation method and easy mass production and consequently is an ideal high-energy lithium ion battery cathode material.

The invention discloses a method for preparing graphene aerogel and graphene/ metallic oxide aerogel. The method is characterized in that graphite oxide aqueous solution serves as a raw material, alcohol serves as a cross-linking agent, a precursor solution is obtained through the simple mixing and dispersing processes, the hydrothermal method is adopted, the freeze drying method or a supercritical drying method is adopted, and then the graphene aerogel is obtained . The graphene/ metallic oxide aerogel can be prepared by adding metallic oxide into the polymeric precursor solution. On one hand, the graphene vinyl aerogel material has the characteristic of the graphene aerogel, and on the other hand, the graphene vinyl aerogel material can have the physicochemical characteristic of the metallic oxide. In addition, the aerogel material has a large specific surface and good electrical conductivity, can directly serve as a supercapacitor electrode, and has large specific capacity, good rate capability and cycling stability. The materials used in the method are low in cost, the industrial process is simple, and the method is friendly to the environment.

The invention relates to an oxidized graphene and graphene reinforced cement based composite material and a preparation method thereof. The oxidized graphene and graphene reinforced cement based composite material comprises the oxidized graphene, the graphene, a dispersing agent, a thickening stabilizer, a water reducer, a defoaming agent and a cement matrix, the mass ratio of the total mass of the oxidized graphene and the graphene to the cement matrix is (0.0005-0.5):1, and the mass ratio of the total mass of oxidized graphene and the graphene to the dispersing agent to the water reducer to the thickening stabilizer to the defoaming agent is 1:(0.05-10):(0.1-20):(0.1-20):(0.05-5). In the composite material, the oxidized graphene and the graphene are dispersed in the cement matrix uniformly; compared with the traditional cement material, the tensile strength, rupture strength and conductivity of the composite material are all improved remarkably; and the composite material has more excellent mechanical property and electrical property, and is applicable to the field of multifunctional construction materials.

The invention relates to a preparation method of a high purity and high concentration graphene suspension, which comprises the following steps of: reacting natural crystalline flake graphite with a strong oxidizer to obtain graphite oxide; spreading the graphite oxide into a dispersing agent, and obtaining a graphene oxide suspension by ultrasonic dispersion; mixing the graphene oxide suspension with hydrazine hydrate under the protection of nitrogen and reacting at constant temperature under ultrasonic radiation to prepare stable graphene suspension. Compared with the traditional method for preparing the graphene suspension, the method introduces ultrasonic in the reduction process of the graphite oxide. The invention has the following advantages that the prepared graphene suspension has high concentration (higher than 1 mg.mL<-1>), high purity (without influence of surface active agents and other impurities), high dispersionstability (time for stable dispersion is more than 60 days) and the like; the graphene prepared by the method has high electrical conductivity (high than 700 S.m<-1>), less number of layers, is simple and easy to implement, and is very suitable for large scale production in industy.

Described is an electrode comprising and preferably consisting of electronically active material (EAM) in nanoparticulate form and a matrix, said matrix consisting of a pyrolization product with therein incorporated graphene flakes and optionally an ionic lithium source. Also described are methods for producing a particle based, especially a fiber based, electrode material comprising a matrix formed from pyrolized material incorporating graphene flakes and rechargeable batteries comprising such electrodes.

The present invention provides a dispersible and electrically conductive nano graphene platelet (NGP) material comprising at least a single-layer or multiple-layer graphene sheet, wherein the NGP material has an oxygen content no greater than 25% by weight and no less than 5% by weight. This NGP material can be produced by: (a) preparing a pristine NGP material from a graphitic material; and (b) subjecting the pristine NGP material to an oxidation treatment. Alternatively, the production process may comprise: (A) preparing a graphite oxide (GO) from a laminar graphite material; (b) exposing the GO to a first temperature for a first period of time to obtain exfoliated graphite; and (c) exposing the exfoliated graphite to a second temperature in a protective atmosphere for a second period of time. Conductive NGPs can find applications in transparent electrodes for solar cells or flat panel displays, additives for battery and supercapacitor electrodes, conductive nanocomposite for electromagnetic wave interference (EMI) shielding and static charge dissipation, etc.

The invention relates to a preparation method of graphene based on ascorbic acid, belonging to the technical field of nano materials. The preparation method comprises the following steps: preparing brown graphite suspending liquid; preparing luminous yellow graphite diluent; preparing graphite oxide solid; dispersing graphite oxide into deionized water, separating graphene oxide by ultrasonic separation treatment for 1 hour and preparing graphene oxide solution; and fully mixing the graphene oxide solution and ascorbic acid water solution, stewing and obtaining the graphene solution. The preparation adopts the ascorbic acid as a reducing agent, shortens reaction time under the condition that no stabilizing agent is added, obtains single-layer grapheme with the thickness of 0.8 to 1.2nm and is beneficial to batch production of the grapheme.

Disclosed is a method for producing colloidal graphene dispersions comprising the steps of

• • (i) dispersing graphite oxide in a dispersion medium to form a colloidal graphene oxide or multi-graphene oxide dispersion
  • (ii) thermally reducing the graphene oxide or multi-graphene oxide in dispersion.

Dependent on the method used for the preparation of the starting dispersion a graphene or a multi-graphene dispersion is obtained that can be further processed to multi-graphene with larger inter-planar distances than graphite. Such dispersions and multi-graphenes are for example suitable materials in the manufacturing of rechargeable lithium ion batteries.

We report a method of preparation of highly elastic graphene oxide films, and their transformation into graphene oxide fibers and electrically conductive graphene fibers by spinning. Methods typically include: 1) oxidation of graphite to graphene oxide, 2) preparation of graphene oxide slurry with high solid contents and residues of sulfuric acid impurities. 3) preparation of large area films by bar-coating or dropcasting the graphene oxide dispersion and drying at low temperature. 4) spinning the graphene oxide film into a fiber, and 5) thermal or chemical reduction of the graphene oxide fiber into an electrically conductive graphene fiber. The resulting films and fiber have excellent mechanical properties, improved morphology as compared with current graphene oxide fibers, high electrical conductivity upon thermal reduction, and improved field emission properties.

The invention discloses a preparation method of a copper-plated graphene reinforced metal-based composite. The preparation method comprises the following steps: firstly, chemically plating the surfaces of oxidized graphene powder with copper to obtain copper-plated graphene powder; ball-grinding and mixing the copper-plated graphene powder and metal powder to obtain copper-plated graphene/metal mixed powder; and performing warm-pressing forming to the copper-plated graphene/metal mixed powder by adopting powder metallurgy warm-pressing technology, sintering, and performing composite processing and forming by adopting extrusion, forging, rolling and other technologies. The copper-plated graphene powder is adopted as a reinforcing body, the preparation method is simple, the cost is low, the designability is strong, and the copper-plated graphene reinforced metal-based composite which is good in interface binding, high in compactness and good in mechanical performance and thermophysical performance can be obtained.

A primary alkaline battery includes a cathode including a nickel oxyhydroxide and an anode including zinc or zinc alloy particles. Performance of the nickel oxyhydroxide alkaline cell is improved by adding zinc fines to the anode and by including an oxidation resistant graphite in the cathode as well as in a conductive coating applied to the inside surface of the cell housing.

The invention provides an oxidized grapheme/carbon black rubber nanocomposite and preparation method thereof, which belongs to the field of rubber nanocomposite technology. The nanocomposite comprises the following basic compositions by mass: 100 parts of diene series rubber matrix, 0.5-5 parts of oxidized grapheme, 30-70 parts of hard carbon black of average particle size 11-30nm, 1-10 parts of plasticizer, 6-10 parts of activator, 0.5-4 parts of anti-aging agent, 1-4 parts of sulfuration promoter and 1-6 parts of insoluble sulphur; oxidized grapheme modifier. The oxidized grapheme powder is dispersed in deionized water for ultrasound, and a natural rubber emulsion is added, and masterbatch after flocculation, washing and drying is mixed uniformly with other additives, after sulfuration, the product is obtained. The oxidized grapheme/carbon black rubber nanocomposite has the advantages of excellent processing performance and obviously reduced dynamic themogenesis, thereby improving the usage life of tyre.

The invention relates to a method for preparing grapheme through oxidation reduction and belongs to grapheme preparation technique. The method specifically comprises the following steps: a modified Hummer method is used for preparing graphite oxide, and an oscillator is adopted for shaking and peeling off single layer graphite oxide softly. During the step of preparing grapheme through reduction, compared with kinds of conventional major reducing agents, the method has the advantages that the reduction procedures and conditions are optimized, and further the grapheme with excellent performance is obtained. In the invention, by optimizing the preparation technique and conditions, the grapheme, which is large in size, is single-layered, is excellent in electrical conductivity and has high quality is obtained, and the method has the characteristics of low cost, high product yield and easiness in industrialization.

The invention relates to a method for preparing nitrogen-doped graphene, in particular to a novel simple, convenient and scale method for preparing nitrogen-doped graphene at high temperature under the protection of inert gas by taking melamine as a nitrogen source. In the method, graphene oxide and the melamine are taken as raw materials, wherein the melamine is taken as the nitrogen source and the graphene oxide is taken as a carbon source; high temperature annealing is carried out in the atmosphere of inert gas, and the reduction of the graphene oxide and the nitrogen doping of graphene are realized; and by controlling reaction conditions such as temperature, time, the ratio of the raw materials and the like, graphene products with different nitrogen doping ratios can be prepared. The preparation method is simple and practicable; catalysts are not needed; the reaction process is easy to control; special requirements on equipment do not exist; the cost is low; and the method is easy to promote and use.

The invention discloses a graphene nano sheet/MoS2 composite nano material and a synthesis method thereof. The method comprises the following steps of: preparing a graphite oxide nano sheet from graphite by using a chemical oxidation method, then dissolving molybdate into deionized water to form a solution of 0.02 to 0.07M, and adding thioacetamide or thiourea serving as a sulfur source and a reducer, wherein the mass ratio of the thioacetamide or the thiourea to the molybdate is 5:1-12:1; and adding the graphite oxide nano sheet into the solution, performing ultrasonic treatment for 1 to 2 hours so that the graphite oxide nano sheet is fully dispersed in a hydrothermal reaction solution, transferring the mixture into a hydrothermal reaction kettle, sealing, reacting for 20 to 36 hours at the temperature of between 220 and 260 DEG C, and obtaining the graphene nano sheet/molybdenum disulfide composite nano material by one-step hydrothermal synthesis, wherein the mass ratio of the graphene nano sheet to the molybdenum disulfide in the composite material is 1:2-4:1. The method has the characteristics of mild reaction condition and simple process. The synthesized graphene nano sheet/molybdenum disulfide composite nano material serving as an electrochemical lithium storage and electrochemical magnesium storage electrode material has wide application.