1071 results about "Nitrogen doped graphene" patented technology

The invention provides nitrogen mixed grapheme hydrogel of which the water content is 90 to 99.5 percent, the electric conductivity is 10-3-100 S/m, and the molar ratio of N and C is 1 to 25 percent. The invention further provides nitrogen mixed aerogel of which the molar ratio of N and C is 2 to 20 percent, the molar ratio of C and O is 15 to 5, nitrogen atoms existing in the form of amidogen nitrogen accounts for 40 to 70 percent, pyridine type nitrogen accounts for 10 to 40 percent, graphite type nitrogen accounts for 10 to 30 percent, the specific area is 300 to 1500 m<2>/g, the apertures which are micropore account for 10 to 20 percent, the apertures which are mesoporous 20 to 50 percent, the apertures which are macropore 30 to 70 percent, the apparent density is 0.01 to 0.2 g/cm<3>, the pore volume is 5 to 20 cm<3>/g, and the electric conductivity is 1 to 1000 S/m. The nitrogen mixed grapheme hydrogel or aerogel and preparation method thereof provided by the invention has the characteristics that the operation is simple, the equipment requirement is low, the production efficiency is high, the scale-up of the technology is easy, the nitrogen mixed content is controllable and the compounding with other functional substances is simple.

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 method for preparing nitrogen-doped graphene which comprises the following steps of: drying a mixture of a carbon-containing precursor and a carbon-nitrogen-containing precursor; raising the temperature of the dried mixture to be 450-600 DEG C, and keeping the temperature to generate gray solid; and continuously raising the temperature of the gray solid to be 700-1000 DEG C, introducing protective gas, keeping the temperature to generate black solid, and obtaining the nitrogen-doped graphene. According to the method for preparing nitrogen-doped graphene in the embodiment, the nitrogen-doped graphene is obtained under normal pressure and high temperature through a solid-phase reaction, the whole preparation method is simple in process, the nitrogen-doped graphene can be obtained without complex equipment, and industrial production is easily performed. In addition, the invention also provides nitrogen-doped graphene.

The invention provides preparation and application of a nitrogen doped graphene fuel cell catalyst, wherein a preparation method of the nitrogen doped graphene fuel cell catalyst is characterized by comprising the following steps: dispersing graphene oxide into a solvent, and carrying out ultrasonic treatment, thereby obtaining a graphene solution; dispersing at least one of non-noble metal salt as well as hydrate thereof and nitrogenous small organic molecules into the solvent, thereby obtaining a mixed solution; dropping the graphene oxide solution into the mixed solution, drying the solvent by distillation, thereby obtaining a nitrogen doped graphene precursor, warming to 600-1000 DEG C under the protection by inert gases, keeping the temperature for 1-4 hours, and cooling naturally, thereby obtaining the doped graphene catalyst. The nitrogen doped graphene preparation process provided by the invention is simple; required raw materials are low in cost, high in yield, can achieve industrial production easily, have very high oxygen reduction catalytic activity, can be applied to the fields of fuel cells, metal-air cells as well as microorganism fuel cells and the like.

The invention discloses a nitrogen-doped graphene/molybdenum disulfide composite material, and a preparation method and application thereof. The nitrogen-doped graphene/molybdenum disulfide composite material is obtained by mixing a graphite oxide solution, a nitrogen-containing precursor, a sulfur-containing precursor and a molybdenum-containing precursor in a solution, removing the solvent or hetero-ion to obtain a precursor material, performing heat treatment on the precursor material under the protection of an inert gas, and performing nitrogen doping and crystallization. The nitrogen-doped graphene/molybdenum disulfide composite material is applicable to lithium ion batteries, sodium cells, magnesium cells, hydrogen generation under electrocatalysis, hydrogen generation under photocatalysis and super capacitors, and is capable of improving the capacity of an anode material and also enhancing the cycling performance and the rate performance of the anode material when being used as a lithium ion battery anode material.

The invention discloses a method for preparing nitrogen-doped graphene with high nitrogen doping amount. The method comprises the following steps: (1) dispersing of graphene; (2) ultrasonic dispersion; (3) microwave heating; and (4) filtering and drying. The nitrogen doping amount of the nitrogen-doped graphene prepared by the method disclosed by the invention is 10%-15.0%, the density of free carriers in graphene is greatly increased by the high nitrogen doping amount, the interaction of graphene and metal is enhanced, no oxidation pretreatment is carried out, no toxic solvent is used in the reaction process, reactants are simple in component, reaction conditions are mild, and the prepared nitrogen-doped graphene has excellent electrochemical property and can be used for preparation of new energy materials such as lithium ion battery, lithium-air battery, super capacitor electrode material and fuel cell oxygen reduction catalysts. According to the method disclosed by the invention, a high-pressure kettle is heated by using microwaves without high temperature; the method is low in energy consumption, is carried out in an airtight environment and therefore hardly causes environment pollution; in addition, the method is simple in process and convenient to operate and needs less production equipment, thus, the cost is further reduced.

The invention provides a nitrogen-doped graphene catalyst and a preparation method and application thereof. The nitrogen-doped graphene catalyst is characterized by being prepared by roasting a nitrogen-doped graphene precursor; the nitrogen-doped graphene precursor is prepared from the raw materials including at least one of non-precious metal salt and hydrate thereof, graphite oxide and nitrogen-containing small organic molecules; in the raw materials, the mass percent of the graphite oxide is 10-89wt%, the mass percent of the nitrogen-containing small organic molecules is 10-89wt%, and the mass percent of at least one of non-precious metal salt and hydrate thereof is 1-10wt%. The preparation process of the nitrogen-doped graphene provided by the invention is simple, the process is easy to operate, the activity is high, the cost is low, and industrial production is easy to implement; the nitrogen-doped graphene can be applied to the fields of fuel cells, metal-air cells, microbial fuel cells and the like.

The invention relates to a novel composite material, and particularly relates to a preparation method and application of a nitrogen-doped graphene and cobaltosic oxide hollow nanosphere composite material. The novel composite material comprises a doped graphene substrate and cobaltosic oxide hollow nanospheres which is attached to the surface of the doped graphene substrate. Melamine resin is taken as a cross-linking reagent for integrating graphite oxide with Co<2+> into a single coordination precursor. The preparation method comprises the following steps: in a pyrolysis process of the precursor, taking the melamine resin as a new nitrogen source to uniformly dope the graphene with nitrogen, fixing cobalt oxide which is generated in situ, and finally preparing the nitrogen-doped graphene/Co3O4 hollow nanosphere composite material with a sandwich structure. The composite material has a graded porous structure, is high in specific surface area, more in active sties, good in electron conductivity and ion conductivity, and good in application prospect in the field of new energy resources and catalysis.

The invention provides a preparation method of nitrogen doped graphene and an application of the nitrogen doped graphene in super capacitors. The preparation method of the nitrogen doped graphene specifically comprises the following steps: putting a carbon material and a compound containing active nitrogen elements in an enclosed container, and heating to a temperature of 100 to 300 DEG C so as to obtain the nitrogen doped graphene. In the preparation process of the nitrogen doped graphene, under a heating condition, nitrogen elements in the compound containing active nitrogen elements are mixed into the carbon material so as to obtain the nitrogen doped graphene. The nitrogen doped graphene preparation method mentioned above avoids adopting a high reaction temperature, and has the advantages of mild preparation conditions and low production cost. The prepared nitrogen doped graphene is used as an electrode material of a super capacitor, and the specific capacity of the super capacitor can reach 190 F/g, when the electric current density is 5 A/g. The capacity retention ratio is 96.3% after 10000 times of circulation.

The invention relates to a method for preparing nitrogen-doped graphene. The method comprises the steps: (1) with foam nickel as a substrate, making dopamine monomers undergo a polymerization reaction on the surface of the substrate to form polydopamine, and thus obtaining PDA-Ni; (2) with the generated PDA-Ni as a solid precursor and the foam nickel as a catalyst and a template, carrying out high temperature annealing in closed inert gas, finally cooling to the room temperature in the closed inert gas, and thus obtaining a foam nickel block NG-Ni coated with the nitrogen-doped graphene product; and (3) etching away the foam nickel template by hydrochloric acid, and thus obtaining a three-dimensional porous nitrogen-doped graphene material without support. By controlling the annealing temperature, a nitrogen doping type can be regulated and controlled. The preparation method is simple and easy to implement, allows the reaction process to be easy to control, has no special requirements on equipment, is low in cost, and is easy to popularize and use.

The present invention provides a preparation method for a nitrogen-doped graphene hydrogel. The preparation method comprises the following steps: (1) adding an oxidized graphite to water according to a certain ratio, and carrying out ultrasonic dispersion to obtain an oxidized graphene aqueous solution; (2) adding an organic amine to the oxidized graphene aqueous solution obtained from the step (1) in a dropwise manner, and stirring for a certain time to form an oxidized graphene and organic amine compounded intermediate product; and (3) carrying out a hydrothermal synthesis reaction on the intermediate product obtained from the step (2) to obtain the nitrogen-doped graphene hydrogel. The method of the present invention is a new and easy method for synthesis and regulation of the three dimensional structure of the graphene, and has characteristics of simple operation, easy control, low cost, no pollution and easy industrialization. With application of the graphene hydrogel of the present invention as a super-capacitor electrode material, results show that good specific capacitance and high power density are provided under the very high charge and discharge current circumstance.

The invention belongs to the technical field of new energy materials and preparation thereof, and relates to a mesoporous graphite type carbon nitride/nitrogen doped graphene sol nanocomposite and a method for preparing the same. The method comprises the following steps that: graphene oxide and a surfactant are added into deionized water and are ultrasonically mixed uniformly to obtain a colloidal solution; mesoporous graphite type carbon nitride is added to be continuously and ultrasonically treated, and a nitrogen-containing compound is then added to be stirred at constant temperature to form a mixed solution; and hydrothermal reaction and natural cooling are then carried out, ammonia which is adsorbed to a material surface is removed through washing, and the material is dried. The yield of the prepared mesoporous graphite type carbon nitride/nitrogen doped graphene sol nanocomposite is high, and the mesoporous graphite type carbon nitride/nitrogen doped graphene sol nanocomposite has a wide application scope, can be applied to fuel cells, photodegradation reactors and the like. The method has the advantages of simplicity in technology, low cost, high yield, short period and environmental friendliness, and can be suitable for industrially producing the mesoporous graphite type carbon nitride/nitrogen doped graphene sol nanocomposite in a large scale.

The invention discloses a three-dimensional nitrogen-doped graphene composite material as well as a preparation method and an application thereof to electrochemical biosensors. By means of the characteristics such as high specific surface area, good biocompatibility and high conductivity of the three-dimensional nitrogen-doped graphene, the three-dimensional nitrogen-doped graphene composite material is constructed; the preparation method comprises the following steps: obtaining substrate-containing three-dimensional nitrogen-doped graphene by taking a foam material as a substrate and utilizing a chemical vapor deposition (CVD) method in the presence of inert gas, hydrogen, a carbon source and a nitrogen source, and obtaining the three-dimensional nitrogen-doped graphene composite material by etching and cleaning the three-dimensional nitrogen-doped graphene. By compounding the three-dimensional nitrogen-doped graphene with enzyme/non-enzyme materials, corresponding three-dimensional nitrogen-doped graphene composite materials can be obtained; the three-dimensional nitrogen-doped graphene composite materials are prepared into electrodes and have the characteristics of being high in current corresponding sensitivity, good in stability and wide in application range when being used for detecting a plurality of molecules such as glucose, dopamine, paracetamol and the like.

The invention relates to the technical field of synthesizing of graphene materials and provides a preparation method of nitrogen-doped graphene. The preparation method includes: using an improved Hummers method to prepare continuous large-piece graphene oxide; using a hydrothermal method to prepare the graphene oxide into graphene of a porous three-dimensional structure; ultrasonically dispersing the graphene of the porous three-dimensional structure into an acid solution with the pH being 1-5, adding aniline, well mixing, adding ammonium persulfate, well mixing, and transferring the obtained mixed liquid into a teflon container for hydrothermal reaction so as to obtain a porous three-dimensional graphene-polyaniline compound; performing high-temperature treatment under nitrogen protection to allow polyaniline to decompose out nitrogen sources so as to obtain the nitrogen-doped porous three-dimensional graphene. The method has the advantages that the nitrogen-doped graphene with high nitrogen content can be prepared, the structure of the three-dimensional graphene can be kept, the obtained nitrogen-doped porous three-dimensional graphene is good in electrochemical performance and quite suitable for being used for producing a super capacitor, and the method is convenient to operate and beneficial to industrial popularization.

A preparation method for a water phase of nitrogen-doped graphene (NG) is characterized in that the preparation method comprises the following steps: mixing 0.5-5mg/mL oxidized graphene water suspension and solid urea as raw materials and dissolving, wherein the mass ratio of the oxidized graphene to the urea is 1 to 0.01; transferring the mixture into a stainless steel reaction kettle; feeding the stainless steel reaction kettle in a drying oven and carrying out constant temperature hydrothermal reaction at the reaction temperature of 150-200DEG C for 5-20 hours; naturally reducing the temperature to room temperature; taking out a sample and soaking or dialyzing with secondary deionized water; and removing the un-reacted urea; freezing and drying to obtain the nitrogen-doped graphene, wherein the nitrogen doping amount is 2.05-8.47 percent and the specific surface area is 450-550m<2>/g. According to the preparation method disclosed by the invention, the control over effective reduction of the nitrogen-doped graphene and the nitrogen doping ratio in the product can be realized by regulating and controlling the conditions such as the reaction temperature, the time, the ratio of a reactant and the like according to the requirement on the properties of products.

The invention provides a preparation method of a nitrogen-doped graphene aerogel supported non-precious metal oxygen reduction catalyst. The method comprises the following steps: stirring a mixed solution of organic amine and aldehyde for 0.5-2 hours at the temperature of 50-90 DEG C, adding graphene oxide and a non-precious salt solution, stirring for 1-24 hours at the temperature of 60-99 DEG C to obtain organogel, performing freezing or supercritical drying, heating to 500-1000 DEG C under protection of inert gas, preserving heat for 1-6 hours, and naturally cooling to room temperature, thereby obtaining the nitrogen-doped graphene aerogel supported non-precious metal oxygen reduction catalyst. The preparation method of the nitrogen-doped graphene aerogel supported non-precious metal oxygen reduction catalyst is simple, the production can be easily expanded, the cost is low, the oxygen reduction catalysis activity is high, and the commercial popularization is facilitated.

The invention provides a transition metal nitride/nitrogen-doped graphene nanometer composite material and a preparation method and application thereof. In the composite material, transition metal nitride nanoparticles with sizes being 5-20 nanometers are embedded into a nitrogen-doped graphene framework, and the composite material is relatively large in specific area, contains mesopores uniformlydistributed and has favorable electrical conductivity. The preparation method of the composite material comprises the steps of (1) mixing a template precursor, a carbon source and a metal source to obtain a mixed material; and (2) placing the mixed material of the step (1) in an atmosphere furnace, and performing calcination in a non-oxidization atmosphere to obtain the transition metal nitride/nitrogen-doped graphene nanometer composite material. The composite material is used for the supercapacitor, a fuel cell or a lithium ion battery and has excellent application prospect. Compared with the prior art, the preparation method of the composite material is simple in process, low in equipment requirement and low in energy consumption, the raw material is low in cost, and mass production iseasy.

The present invention relates to a method of preparing a nitrogen-doped graphene comprising preparing a Edge-Functionalized Graphene by binding a graphite with a organic material having amino groups and functional groups such as carboxy acid group through an electrophilic substitution reaction, and heat treating the resultant Edge-Functionalized Graphene, and a nitrogen-doped graphene prepared thereby. According to the present invention, by a more inexpensive and simpler method, a nitrogen-doped graphene can be prepared at higher purity and higher yield. The nitrogen-doped graphene obtained by the present invention has very excellent physical and electric properties, and particularly has a superior oxygen reduction capability, compared with the platinum catalyst used at cathode of a H₂/O₂ fuel cell so that it will replace the platinum to lower more the cost of a H₂/O₂ fuel cell or to increase its life and further to provide a new turning point for the commercialization of a H₂/O₂ fuel cell.

The invention discloses a nitrogen-doped graphene-metal oxide nanocomposite material as well as a preparation method and application thereof. The nitrogen-doped graphene-metal oxide nanocomposite material is obtained by performing reaction on nitrogen-doped graphene and a metal salt in an organic solvent in a solvothermal way, wherein the nitrogen-doped graphene is obtained by performing reaction on oxidized graphene or partially-reduced graphene and a nitrogen-enriched substance in a water solution. The nitrogen-doped graphene-metal oxide nanocomposite material is simple in process, relatively low in cost, and good in operability and repeatability; by the preparation method, the problems that the nitrogen doping content of a carrier in the composite material is not high, in-situ growth of metal oxide particles on the surface of the graphene is not uniform and the particle size is large are solved; the nitrogen-doped graphene-metal oxide nanocomposite material can be applied to lithium ion batteries and supercapacitors on a large scale.

The invention provides a method for preparing nitrogen-doped graphene with a combustion synthesis method. The method comprises steps as follows: (1) weighed magnesium powder, a solid carbon source and a nitrogen source are evenly mixed, mixed powder is obtained, and the mass ratio of the magnesium powder, the solid carbon source and the nitrogen source in the mixed power is (19.95-99):(40-79.95):(1-39.5); (2) the mixed powder obtained in Step (1) has a combustion synthesis reaction in a specific atmosphere, a reaction product is purified, and the nitrogen-doped graphene is obtained. With the adoption of the method, raw materials are wide in source, the prepared nitrogen-doped graphene is complete in sheet-like structure, good in dispersity in a solvent and large in effective specific surface area, and the nitrogen-doped graphene has the ferromagnetism through nitrogen doping.

The invention provides a graphene-coated lithium iron phosphate positive electrode material and a preparation method thereof, relating to the technical field of batteries. The graphene-coated lithium iron phosphate positive electrode material is a nitrogen-doped graphene-coated lithium iron phosphate positive electrode material. The preparation method comprises the following steps: preparing a mixture A of graphene oxide and nitrogen source dopant; preparing lithium source dispersion liquid, phosphorus source dispersion liquid and iron source dispersion liquid, mixing the lithium source dispersion liquid, the phosphorus source dispersion liquid and the iron source dispersion liquid with the mixture A, and drying to obtain a nitrogen-doped graphene-coated lithium iron phosphate precursor; preheating the precursor, and then sintering in an inert atmosphere to obtain the nitrogen-doped graphene-coated lithium iron phosphate positive electrode material. In a product prepared by the invention, a lithium iron phosphate surface is coated with nitrogen-doped graphene, so that a good electric channel is provided for lithium iron phosphate, so that lithium iron phosphate shows good rate capability.