20536 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 full-carbon coaxial line and a manufacturing method of the full-carbon coaxial line, and belongs to the technical field of integrated circuits. Graphene serves as a monatomic layer thickness, is coiled into a cylinder and form an inner conductor of the coaxial line with a small radius (can be as small as the nm level), and the inner conductor of the coaxial line transfers currents. Meanwhile, a signal layer or multiple layers of graphene serve(s) as an outer conductor of the coaxial line to form a boundary of electromagnetic waves in a space, and graphite oxide serves as medium materials between the inner conductor and the outer conductor to limit and guide oriented transmission of electromagnetic wave energy. The coaxial line is quite small in size and applicable to radio-frequency and microwave integrated circuits.

Disclosed are methods for preparing electrophoretically deposited graphene based films.

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 method for preparing graphene powder in large scale, which is characterized by comprising the following steps of: firstly, uniformly peeling graphene oxide into a graphene oxide suspension solution; then, atomizing the graphene oxide solution by using the spray drying technology comprising spray pyrolysis drying and spray freeze drying, and removing a solvent to obtain graphene oxide powder; and finally, oxidizing grapheme by using the non-expansion heat treatment process to obtain non-agglomerative graphene powder. The continuous preparation process of the spray technology and the non-expansion heat treatment process ensure the large-scale preparation of the graphene powder. The prepared graphene powder comprising intermediate product graphene oxide powder does not have agglomeration and has good dispersivity in the solvent. The graphene powder is used as a filling material to prepare high strength composite materials, conductive composite materials, novel air-tight flame-retardant composite materials, novel nanodevices and the like.

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.

A field effect transistor (FET) with a source electrode and a drain electrode distanced apart from each other on a semi-conductor substrate, and a gate electrode consisting of a uniform layer of reduced graphene oxide encapsulated semiconductor nanoparticles (rGO-NPs), wherein the gate electrode is disposed between and contacts both the source and drain electrodes. Methods of making and assay methods using the FETs are also disclosed, including methods in which the rGO-NPs are functionalized with binding partners for biomarkers.

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 preparation method of a silicon and carbon-coated graphene composite cathode material. The technical problem to be solved is to enhance the electronic conductivity of the silicon-based cathode material, buffer the volume effect produced in the process of deintercalation of the lithium in the silicon-based cathode material and enhance the structure stability in the circulation process of the material at the same time. The material is prepared by using a spray drying-thermally decomposing treatment process in the invention. The preparation method comprises the following steps of: evenly dispersing nano silicon and graphite micro powder in a dispersion solution of oxidized graphene, carrying out thermal treatment under an inert protection atmosphere after spray drying, subsequently cooling along a furnace to obtain the silicon and carbon-coated graphene composite cathode material. The extra binder does not need to add in the process of manufacturing balls in the invention and the outer oxidized graphene is thermally reduced in situ to graphene in the thermal treatment process of the composite precursor, so that the process is simple and easy to operate; and the practical degree is high. The prepared composite material has the advantages of great reversible capacity, designable capacity, good cycling performance and high-current discharging performance, high tap density and the like.

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.