CN104058399B - A kind of direct preparation method of high-purity and high-quality graphene - Google Patents

Abstract

The invention discloses a direct preparation method of high-purity and high-quality graphene, which belongs to the technical field of chemical synthesis. The method of the invention takes alkali metals or alkaline earth metals and polyhalogenated hydrocarbons as raw materials, and directly prepares graphene by performing metal coupling reaction in polyhalogenated hydrocarbons or benign solvents in an inert environment, and then uses alcohol, water or acid. High-quality graphene is obtained by reacting with the remaining active alkali metal or alkaline earth metal; and then high-purity graphene is obtained after processing procedures such as organic solvent washing, acid washing, water washing, filtration, and drying. The method of the invention has the advantages of simple equipment, easy operation, low cost, few by-products, high yield and high purity. , has broad application prospects in microelectronics.

Description

A kind of direct preparation method of high-purity and high-quality graphene

technical field

The invention relates to a graphene preparation method, and belongs to the technical field of graphene chemical synthesis.

Background technique

Graphene is a new material with a single-layer sheet structure composed of carbon atoms. It is a ^two -dimensional material with a thickness of only one carbon atom. Graphene is currently the thinnest but also the hardest nanomaterial in the world. It is almost completely transparent and absorbs only 2.3% of light; its thermal conductivity is as high as 5300W/m K, which is higher than that of carbon nanotubes and diamonds. The mobility exceeds 15000cm2/V·s, which is higher than that of carbon nanotubes or silicon crystals, while the resistivity is only about 10 ^-6 Ω·cm, which is lower than that of copper or silver, making it the material with the smallest resistivity in the world. Because of its extremely low resistivity and extremely fast electron migration, it is expected to be used to develop a new generation of electronic components or transistors that are thinner and conduct electricity faster. Since graphene is essentially a transparent and good conductor, it is also suitable for making transparent touch screens, light panels, and even solar cells. Graphene is a new type of carbon material that has been extensively studied in recent years.

Graphene has a wide range of applications. According to the ultra-thin and super-strength characteristics of graphene, graphene can be widely used in various fields, such as ultra-light body armor, ultra-thin and ultra-light aircraft materials, etc. According to its excellent electrical conductivity, it also has great application potential in the field of microelectronics. Graphene has the potential to be a substitute for silicon, making ultra-tiny transistors for future supercomputers, where carbon's higher electron mobility could enable future computers to achieve higher speeds. In addition, graphene material is also an excellent modifier. In the field of new energy such as supercapacitors and lithium-ion batteries, due to its high conductivity and high specific surface area, it can be used as an electrode material assistant.

Graphene is by far the strongest material in the world. It is estimated that if graphene is used to make a film with a thickness equivalent to the thickness of an ordinary food plastic packaging bag (thickness is about 1 million nanometers), it will be able to withstand about two tons of heavy items. Pressure without breaking; second: Graphene is the most conductive material in the world.

Graphene has a wide range of applications. According to the ultra-thin and super-strength characteristics of graphene, graphene can be widely used in various fields, such as ultra-light body armor, ultra-thin and ultra-light aircraft materials, etc. According to its excellent electrical conductivity, it also has great application potential in the field of microelectronics. Graphene has the potential to be a replacement for silicon, making ultra-tiny transistors for future supercomputers, where carbon's higher electron mobility could enable future computers to achieve higher speeds. In addition, graphene material is also an excellent modifier. In the field of new energy such as supercapacitors and lithium-ion batteries, due to its high conductivity and high specific surface area, it can be used as an electrode material assistant.

The research boom of graphene has also attracted the interest of material preparation research at home and abroad. The preparation methods of graphene materials have been reported as follows: mechanical exfoliation method, chemical oxidation method, crystal epitaxy growth method, chemical vapor deposition method, organic synthesis method and carbon Nanotube exfoliation, etc.

micromechanical peeling

In 2004, Geim et al. used the micromechanical exfoliation method for the first time to successfully exfoliate and observe single-layer graphene from highly oriented thermally cracked graphite. Using this method, Geim's research group successfully prepared quasi-two-dimensional graphene and observed its morphology, revealing the reason for the existence of graphene's two-dimensional crystal structure. The micromechanical exfoliation method can prepare high-quality graphene, but it has the disadvantages of low yield and high cost.

chemical vapor deposition

For the first time, chemical vapor deposition (Chemical Vapor Deposition, CVD) has made a new breakthrough in the problem of large-scale preparation of graphene (refer to the preparation of high-quality graphene by chemical vapor deposition). The CVD method refers to the chemical reaction of reactants under gaseous conditions, and the formation of solid substances deposited on the surface of the heated solid substrate to obtain solid materials. Kong et al., MIT, Hong et al. and Chen et al. of Purdue University using the CVD method to prepare graphene. They used a simple tubular deposition furnace with nickel as the substrate, and passed carbon-containing gas, such as hydrocarbons, which decomposed into carbon atoms and deposited on the surface of nickel at high temperature to form graphene, through slight By chemical etching, the graphene film and the nickel sheet are separated to obtain the graphene film. The conductivity of this film can reach 1.1×10 ⁶ S/m when the light transmittance is 80%, and it becomes a potential substitute for transparent conductive films. High-quality and large-area graphene can be prepared by CVD, but the ideal substrate material, single-crystal nickel, is too expensive, which may be an important factor affecting the industrial production of graphene. The CVD method can meet the requirements of large-scale production of high-quality graphene, but the cost is high and the process is complicated.

redox method

The oxidation-reduction method has low preparation cost and is easy to realize, and has become the best method for preparing graphene, and can prepare stable graphene suspension, which solves the problem that graphene is not easy to disperse. The oxidation-reduction method refers to the reaction of natural graphite with strong acids and strong oxidizing substances to form graphite oxide (GO), which is prepared into graphene oxide (single-layer graphite oxide) by ultrasonic dispersion, and a reducing agent is added to remove the oxygen-containing surface of the graphite oxide. groups, such as carboxyl, epoxy, and hydroxyl groups, give graphene. After the oxidation-reduction method was proposed, it became the easiest way to prepare graphene in the laboratory because of its simple and easy process, and was favored by the majority of graphene researchers. Ruoff et al. found that graphene can be obtained by adding chemicals such as dimethylhydrazine, hydroquinone, sodium borohydride (NaBH ₄ ) and liquid hydrazine to remove the oxygen-containing groups of graphene oxide. The oxidation-reduction method can prepare stable graphene suspensions, which solves the problem that graphene is difficult to disperse in solvents. The disadvantage of the oxidation-reduction method is that the large-scale preparation is easy to cause waste liquid pollution and the prepared graphene has certain defects, for example, topological defects such as five-membered rings and seven-membered rings or structural defects with -OH groups, which will This leads to the loss of some electrical properties of graphene, which limits the application of graphene.

solvent stripping

The principle of the solvent exfoliation method is to disperse a small amount of graphite in a solvent to form a low-concentration dispersion liquid, and use the action of ultrasonic waves to destroy the van der Waals force between the graphite layers. At this time, the solvent can be inserted between the graphite layers to exfoliate layer by layer. Graphene. This method does not destroy the structure of graphene like the oxidation-reduction method, and can prepare high-quality graphene. The highest yield of graphene (approximately 8%) was found in nitrogen methylpyrrolidone with a conductivity of 6500 S/m. It is found that highly oriented thermally cracked graphite, thermally expanded graphite and microcrystalline artificial graphite are suitable for the preparation of graphene by solvent exfoliation. The solvent exfoliation method can prepare high-quality graphene, and the entire liquid phase exfoliation process does not introduce any defects on the surface of graphene, which provides a broad application prospect for its applications in microelectronics, multifunctional composite materials and other fields. The disadvantage is that the yield is very low.

solvothermal method

The solvothermal method refers to the preparation of materials by heating the reaction system to a critical temperature (or close to the critical temperature) in a special closed reactor (autoclave), using an organic solvent as a reaction medium, and generating high pressure in the reaction system itself. an effective method. The solvothermal method solves the problem of large-scale preparation of graphene, but also brings the negative effect of low electrical conductivity. In order to solve the shortcomings caused by this, the researchers combined the solvothermal method and the redox method to prepare high-quality graphene. Dai et al. found that the resistance of graphene sheets prepared by reducing graphene oxide under solvothermal conditions was lower than that prepared under traditional conditions. The solvothermal method has attracted more and more attention of scientists due to the characteristics of preparing high-quality graphene in a closed system at high temperature and high pressure.

other methods

The preparation methods of graphene include high temperature reduction, photoreduction, epitaxial crystal growth method, microwave method, arc method, electrochemical method, etc. At present, the production methods of graphene mainly include mechanical exfoliation method and thermal expansion graphite method. Among them, the mechanical peeling method is to repeatedly bond and peel the expensive highly oriented pyrolytic graphite with adhesive tape, and finally transfer it to the surface of the base material. This method has low efficiency, small yield and high cost, and can only be limited to laboratory production. However, the thermally expanded graphite method has complicated steps and great damage to the graphene structure. Based on the above methods, this paper proposes a method for preparing high-quality graphene by polyhalogenated hydrocarbons through active metal coupling reaction combined with redox method. This method is rich in raw materials, green and environmentally friendly, and can realize a new method for large-scale production.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the problems existing in the prior art, and to provide a method that is simple in method, environmentally friendly in process, low in cost, and capable of large-scale preparation of high-quality graphene.

The invention discloses a direct preparation method of high-purity and high-quality graphene, which belongs to the technical field of chemical synthesis. The method of the present invention uses alkali metals or alkaline earth metals and polyhalogenated hydrocarbons as raw materials, and carries out metal coupling reaction in the polyhalogenated hydrocarbon bulk or benign solvent under an inert environment, and the molar ratio of metal and polyhalogenated hydrocarbons is preferably 0.5. Between -30 and 0.1-72 hours at 0-300°C to obtain crude graphene, and then use water, alcohol or acid to remove remaining alkali metals or alkaline earth metals to prepare high-quality graphene, which is then washed with organic solvents, High-purity and high-quality graphene is obtained after acid washing, water washing, filtration and drying. The method of the invention has the advantages of simple method, easy operation, low cost, few by-products, high yield and high purity, etc. The graphene of the invention is used as a chemical reaction raw material, conductive material preparation, catalyst carrier, battery electrode material, physics, micro It has broad application prospects in electronics.

The method for directly preparing high-purity and high-quality graphene according to the present invention is characterized in that, using active alkali metal or alkaline earth metal and polyhalogenated hydrocarbons as raw materials, and directly preparing high-purity and high-quality graphene through the metal coupling reaction of halogenated hydrocarbons Graphene, including the following steps:

(1) Under the protection of inert gas, the active alkali metal or alkaline earth metal is dispersed in the polyhalogenated hydrocarbon body or its benign solvent to carry out the coupling reaction, or the polyhalogenated hydrocarbon body or its solution is added dropwise or an active base is added. In the metal or alkaline earth metal reaction system, the coupling reaction is carried out in a closed container at 0-300° C. for 0.1-72 hours to obtain a suspension of the crude graphene product;

(2) in above-mentioned suspension, add alcohol, water or acid and react with remaining active alkali metal or alkaline earth metal to obtain high-quality graphene;

(3) after this mixture is filtered, carry out repeatedly organic solvent washing, acid washing, water washing, drying after filtration, remove the solvent and by-product of the graphene crude product in the suspension solution, and obtain high-purity graphene.

The preparation method according to claim 1, wherein the polyhalogenated hydrocarbon is a polyhalogenated aromatic hydrocarbon, a polyhalogenated fused ring hydrocarbon or a mixture thereof, and its characteristic structural formula is as shown in FIG. The group is F, Cl, Br, I atom, trihalogenated vinyl group or pentahalogenated phenyl group, X group is the same or different halogen atom or group, and the polyhalogenated hydrocarbon is: tetrabromo(fluorine) , chloro or iodo) ethylene, hexabromo (fluoro, chloro or iodo)-1,3-butadiene; hexabromo (fluoro, chloro or iodo) benzene, trichlorotribromo (fluoro or iodo) benzene; octachloro (Fluorine, bromine or iodine) naphthalene, tetrachlorotetrabromo (fluorine or iodine) naphthalene; decachloro (fluorine, bromine or iodine) anthracene (phenanthrene), hexabromo (iodine) tetrachloroanthracene (phenanthrene), hexachlorotetrabromo Anthracene (phenanthrene); such as decachloro (fluorine, bromine, iodine) pyrene, hexabromotetrachloropyrene, tetrabromohexachloropyrene; perchloro (fluorine, bromine, iodine) substituted biphenyl, perchloro (bromine, iodine) substituted Terphenyl, polychlorinated (bromo, iodo) benzoanthracene (pyrene), etc., most preferably tetrabromo (chloro) ethylene, hexabromo (chloro or fluoro) benzene, octabromo (chloro or fluoro) naphthalene, decabromo ( One or more mixtures of chloro or fluoro) anthracene (phenanthrene), decabromo (chloro or fluoro) pyrene, perchloro (bromo) biphenyl.

The preparation method of claim 1, wherein the alkali metal or alkaline earth metal is selected from one or a combination of active metals lithium, sodium, potassium, magnesium, calcium, strontium, barium, and lanthanum, Most preferably, it is one or a combination of lithium, sodium, potassium, and magnesium.

The preparation method of claim 1, wherein the polyhalogenated hydrocarbon solvent is selected from the group consisting of solvents that do not react with raw materials alkali metals or alkaline earth metals and polyhalogenated hydrocarbons, and is C5-C20 alkane, C1-C16 Ethers (simple ethers or mixed ethers), C1-C5 alkyl substituted aromatic hydrocarbons or acetal solvents, etc., specifically paraffin oil, (methyl, ethyl) tetrahydrofuran, dioxane, ethylene (propylene, butyl) , pentyl, hex) ether, methyl ethyl (propyl, butyl, amyl, hex) ether, ethyl propylene (butyl, amyl, hex) ether, propyl (butyl, amyl, hex) ether, (tri-condensation, di-condensation, one-contraction) Ethylene (propyl, butylene) glycol dimethyl (ethyl, propyl, butyl, phenyl) ether, benzyl (ethyl, propyl, butyl) ether, diphenyl ether, dimethyl (ethyl, propyl, butyl) phenyl ether, benzyl Ether, glycerol ether, eicosane, methyl (b, c, butyl) benzene, dimethyl (b, c, butyl) benzene, trimethyl (b, c, butyl) benzene, biphenyl, dimethyl biphenyl one or a mixture of several.

The preparation method of claim 1, wherein the molar ratio between the alkali metal or alkaline earth metal and the polyhalogenated hydrocarbon is in the range of 0.1-100, most preferably in the range of 0.5-30.

The preparation method according to claim 1, characterized in that, the polyhalogenated hydrocarbon body or its solution is directly mixed and reacted with the active metal or added dropwise or added to the polyhalogenated hydrocarbon body or its solution as the reaction proceeds. In the active metal reaction solution, or in the polyhalogenated hydrocarbon bulk or solution, the active metal is added or supplemented to carry out the coupling reaction.

The preparation method according to claim 1, wherein the alcohol, water or acid used to reduce or eliminate residual alkali metal or alkaline earth metal are selected from methanol, ethanol, propanol, isopropanol, n-butanol, ethylene glycol , propylene glycol, glycerol, water, hydrochloric acid, hydrobromic acid, hydroiodic acid, hydrofluoric acid, sulfuric acid, phosphoric acid, nitric acid, oxalic acid, formic acid, acetic acid, one or more compositions react with the remaining alkali metal or alkaline earth metal high-quality graphene.

preparation method as claimed in claim 1, it is characterized in that used organic solvent washing, acid washing, washing with water and then filtering and drying, and the solvent used is one of petroleum ether, acetone, ether, ethanol, methanol, DMAc or DMF or A variety of detergents are used to remove the residual reaction solvent, and the washing acid is one or more combination solutions in hydrochloric acid, hydrobromic acid, hydroiodic acid, hydrofluoric acid, sulfuric acid, phosphoric acid, nitric acid, oxalic acid, formic acid, and acetic acid, The residual salt is removed by washing with deionized water, dried and stored to obtain high-purity graphene.

The preparation method of claim 1, wherein the reaction is carried out at a temperature in the range of 0°C to 300°C, most preferably 30°C-180°C; but if sodium metal is used to couple tetrachloroethylene , hexachlorobenzene, bromobenzene or tetrabromoethylene, the reaction temperature is limited to below 120 °C, that is, the sodium metal coupling reaction in the range of 120-400 °C is not included.

preparation method as claimed in claim 1 is characterized in that described reaction pressure range is 0.1-5Mpa, can carry out under normal pressure or pressurized reaction condition, and the activity corresponding to reaction raw material metal and polyhalogenated hydrocarbon, but When the polyhalogenated hydrocarbon is hexachlorobenzene, the reaction is limited to atmospheric pressure.

The preparation method of Graphene of the present invention has the following advantages:

1. The reaction can be carried out under normal pressure and low temperature conditions, the equipment is simple, the operation is easy, the process steps are few, and it is easy to carry out large-scale industrial production;

2. The cost of raw materials is low, the by-products are few, and the solvent can be recycled, which is an atom-economical green synthesis method;

3. The reaction yield is high, even up to 100%, the product quality is high, and the conductivity is strong;

Based on the above advantages, the graphene of the present invention has broad application prospects in the aspects of chemical reaction raw material, conductive film preparation, catalyst carrier, battery electrode material, physics, and microelectronics.

Description of drawings in the manual:

Fig. 1 polyhalogenated hydrocarbon unit structure of synthetic graphene;

The scanning electron microscope photograph of Fig. 2 graphene;

Figure 3 EDS energy spectrum data of graphene;

The XRD spectrum data of Fig. 4 graphene;

Figure 5 Graphene BET specific surface area test (ASAP2010).

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

The methods used in the following examples are conventional methods unless otherwise specified. However, if this example needs to be repeated, special attention should be paid to the danger of deflagration and explosion. Ordinary graduate students or technical staff should not experiment without authorization, and researchers with rich experience in synthesis should be cautious. test.

The specific method for preparing graphene in this embodiment includes the following steps.

Embodiment 1, the synthesis of graphene

In a clean and dry reaction kettle, add 100 mL of toluene, 3.0 g of metallic sodium, and 6.0 g of hexabromobenzene, reflux under argon for 8 hours, stop heating, cool to room temperature to obtain a black graphene suspension, and then add 30 milliliters of absolute ethanol, after stirring and reacting for 2 hours, the obtained graphene crude product was filtered under reduced pressure, washed with acetone for 3 times, washed with water 3 times, washed with 10% hydrochloric acid for 2 times, and then washed with water to neutrality for many times. Vacuum drying to obtain pure graphene.

Embodiment 2, the synthesis of graphene

In a clean and dry reactor, add 10 mL of xylene, 50 mL of tetrahydrofuran, 3.0 g of metallic sodium, and 6.0 g of hexabromobenzene. After refluxing for 10 hours, stop heating and cool to room temperature to obtain a black graphene suspension, and then add 30 mL of Anhydrous methanol, after stirring and reacting for 2 hours, the obtained graphene crude product was filtered under reduced pressure, washed with acetone 3 times, washed with water 3 times, washed with 10% sulfuric acid 2 times, washed with water for many times until neutral, and dried in vacuum Graphene pure product is obtained.

Embodiment 3, the synthesis of graphene

In a clean and dry reaction kettle, add 100 mL of diphenyl ether, 3.0 g of metallic sodium, and 5.0 g of hexabromobenzene. After reacting at 110 ° C for 8 hours, stop heating and cool to room temperature to obtain a black graphene suspension, and then add 30 mL of Dehydrated ethanol, after stirring and reacting for 2 hours, the obtained graphene crude product was filtered under reduced pressure, washed with acetone for 3 times, washed with water for 3 times, washed with 10% hydrochloric acid for 2 times, washed with water for many times until neutral, and dried in vacuum. Graphene pure product is obtained.

Embodiment 4, the synthesis of graphene

In a clean and dry reactor, add 100 mL of tetrahydrofuran, 3.0 g of potassium metal, and 4.0 g of hexabromobenzene. After refluxing for 10 hours, stop heating and cool to room temperature to obtain a black graphene suspension, and then add 25 mL of methanol and stir the reaction. After 2 hours, the obtained graphene crude product was filtered under reduced pressure, washed with acetone for 3 times, washed with water for 3 times, washed with 10% hydrochloric acid for 2 times, washed with water for many times until neutral, and vacuum-dried to obtain pure graphene.

Embodiment 5, the synthesis of graphene

In a clean and dry reaction kettle, add 100 mL of tetrahydrofuran, 3.0 g of potassium metal, and 4.0 g of decabromanthracene, and after refluxing for 10 hours, stop heating, cool to room temperature to obtain a black graphene suspension, then add 50 mL of ethanol, and stir the reaction After 2 hours, vacuum and suction filtration were used to obtain a crude graphene product, which was washed with ether for 3 times, washed with water for 3 times, washed with 10% hydrochloric acid for 2 times, washed with water for many times until neutral, and vacuum-dried to obtain pure graphene.

Embodiment 6, the synthesis of graphene

In a clean and dry reaction kettle, add 100 mL of xylene, 5.0 g of potassium metal, 2.0 g of tetrabromoethylene, 2.0 g of hexabromobenzene, and 4.0 g of decabromopyrene. After refluxing for 10 hours, stop heating and cool to room temperature to obtain a black color. The graphene suspension was then added with 30 milliliters of anhydrous methanol, and after stirring and reacting for 2 hours, the thick graphene product was obtained by suction filtration under reduced pressure. washed to neutrality, and vacuum-dried to obtain pure graphene.

Embodiment 7, the synthesis of graphene

In a clean and dry reactor, add 100 mL of trimethylbenzene, 6.0 g of metallic sodium, 5.0 g of hexabromobenzene, 2.0 g of hexachlorobenzene, and 4.0 g of decabromanthracene. After refluxing for 10 hours, stop heating and cool to room temperature to obtain a black color. The graphene suspension was then added with 30 milliliters of absolute ethanol, and after stirring and reacting for 2 hours, the thick graphene product was obtained by suction filtration under reduced pressure. washed to neutrality, and vacuum-dried to obtain pure graphene.

Embodiment 8, the synthesis of graphene

In a clean and dry reactor, add 100 mL of diphenyl ether, 3.0 g of metallic lithium, 5.0 g of hexabromobenzene, and 4.0 g of decabromphenanthrene, and after refluxing for 10 hours, stop heating and cool to room temperature to obtain a black graphene suspension. Then add 30 ml of absolute ethanol, stir and react for 2 hours, filter under reduced pressure to obtain a thick graphene product, wash with ether 3 times, wash 3 times with water, wash 2 times with 10% hydrochloric acid, and then wash with water for many times until neutral , and vacuum drying to obtain pure graphene.

Embodiment 9, the synthesis of graphene

In a clean and dry reaction kettle, add 100 mL of tetrahydrofuran, 7.0 g of potassium metal, 5.0 g of hexabromobenzene, and 4.0 g of decabromopyrene, and after refluxing for 10 hours, stop heating, cool to room temperature to obtain a black graphene suspension, and then add 30 milliliters of absolute ethanol, after stirring and reacting for 2 hours, the obtained graphene thick product was filtered under reduced pressure, washed with ether for 3 times, washed with water 3 times, washed with 10% hydrochloric acid for 2 times, and then washed with water to neutrality for many times. Vacuum drying to obtain pure graphene.

Embodiment 10, the synthesis of graphene

In a clean and dry reaction kettle, add 100 mL of dioxane, 6.0 g of magnesium metal, 6.0 g of hexabromobenzene, 4.0 g of decabromanthracene, 2.0 g of decabrompyrene, and reflux for 10 hours, then stop heating and cool to room temperature Obtain black graphene suspension, then add 30 milliliters of absolute ethanol, stir and react after 2 hours, the graphene thick product obtained by vacuum suction filtration, then wash 3 times with ether, wash 3 times with water, wash 2 times with 10% hydrochloric acid, Then wash with water for several times until neutral, and vacuum dry to obtain pure graphene.

Embodiment 11, the synthesis of graphene

In a clean and dry reactor, add 100 mL of ethylene glycol dimethyl ether, 4.0 g of tetrabromoethylene, 6.0 g of potassium metal, 6.0 g of hexabromobenzene, 4.0 g of decabromanthracene, and 2.0 g of decabromypyrene, and the reaction was carried out under reflux. After 10 hours, stop heating, cool to room temperature to obtain black graphene suspension, then add 30 milliliters of absolute ethanol, stir and react for 2 hours, filter the obtained thick graphene product under reduced pressure, wash with ether 3 times, wash with water 3 times and 10% hydrochloric acid for 2 times, and then repeatedly washed with water until neutral, and vacuum dried to obtain pure graphene.

Embodiment 12, the synthesis of graphene

In a clean and dry reactor, add 100 mL of diphenyl ether, 2.0 g of tetrachloroethylene, 6.0 g of potassium metal, 6.0 g of hexaiodobenzene, 3.0 g of decabromanthracene, and 1.0 g of decabromopyrene, and the reaction was stopped after refluxing for 10 hours. Heating, cooling to room temperature to obtain black graphene suspension, then adding 30 milliliters of absolute ethanol, stirring and reacting for 2 hours, the obtained graphene thick product by suction filtration under reduced pressure, then washed 3 times with ether, washed 3 times with water, 10% Washed with hydrochloric acid twice, washed with water for several times until neutral, and dried in vacuum to obtain pure graphene.

Embodiment 13, the synthesis of graphene

In a clean and dry reactor, add 100 mL of diphenyl ether, 2.0 g of tetrachloroethylene, 6.0 g of potassium metal, 6.0 g of hexabromobenzene, 3.0 g of decabromanthracene, 1.0 g of decabromodiphenyl, and reflux for 10 hours. Stop heating, cool to room temperature to obtain black graphene suspension, then add 30 milliliters of dehydrated alcohol, stir and react for 2 hours, filter the obtained thick graphene product under reduced pressure, wash with ether 3 times, wash with water 3 times, 10 % hydrochloric acid was washed twice, then washed with water for several times until neutral, and vacuum-dried to obtain pure graphene.

Embodiment 14, the synthesis of graphene

In a clean and dry reactor, add 100 mL of diphenyl ether, 8.0 g of potassium metal, 2.0 g of carbon tetrachloride, 2.0 g of tetrachloroethylene, 6.0 g of hexaiodobenzene, 3.0 g of decabromoanthracene, and 1.0 g of perbromoterphenyl. gram, after 10 hours of reflux reaction, stop heating, be cooled to room temperature to obtain black graphene suspension, then add 30 milliliters of absolute ethanol, after stirring reaction for 2 hours, the thick graphene product obtained by vacuum suction filtration, then clean with ether 3 times, washed 3 times with water, washed 2 times with 10% hydrochloric acid, then washed with water for many times until neutral, and vacuum dried to obtain pure graphene.

The graphene crystal grains prepared in Example 1 were detected by the following method.

1. Graphene grain scanning electron microscope (SEM) and X-ray energy spectrometer characterization

The graphene grains prepared in Example 1 were characterized by scanning electron microscopy (SEM), and the method was as follows: take a small amount of graphene black powder, ultrasonically disperse it in absolute ethanol, and then drop 1-2 drops on the sample table to dry. Dry spray gold, and then observe the prepared graphene grain structure by scanning electron microscope, as shown in Figure 2, and test its EDAX data at the same time, as shown in Figure 3: In the scanning electron microscope photo of the graphene grain in Figure 2 It can be seen that the graphene grain structure prepared by the method of the present invention has a size up to below the micron level; Fig. 3 is its energy spectrum data, it can be seen that the graphene grain is mainly composed of element C and residual halogen, and carbon atoms The content is 90.26%, and the residual halogen atom content is 3.97%.

2. XRD characterization of graphene grains

The graphene prepared in Example 1 was characterized by XRD of graphene grains. As shown in FIG. 4 , the characteristic absorption peaks of graphene with 2θ between 15 and 35 can be seen from the XRD pattern of graphene grains.

3.BET specific surface test

Using N as the adsorption gas, the graphene grains prepared in Example ₁ were subjected to a BET specific surface area test (ASAP2010). As shown in FIG. 5 , the BET specific surface of the prepared graphene grains was 1.37 m ² /g, the total pore volume was 0.013 mL/g, and the average pore diameter was 32.9 nm.

Claims (5)

1. A direct preparation method of high-purity high-quality graphene is characterized in that active alkali metal or alkaline earth metal and polyhalogenated hydrocarbon are used as raw materials, and the high-purity high-quality graphene is directly prepared through metal coupling reaction of the halogenated hydrocarbon, and comprises the following steps:

(1) under the protection of inert gas, dispersing active alkali metal or alkaline earth metal in a polyhalogenated hydrocarbon benign solvent for coupling reaction, and performing coupling reaction in a closed container at the temperature of 0-300 ℃ for 0.1-72 hours to prepare suspension of a graphene crude product; under the condition of normal pressure reflux reaction;

(2) adding alcohol, water or acid into the suspension to react with the residual active alkali metal or alkaline earth metal to prepare high-quality graphene;

(3) filtering the mixture, washing the mixture with an organic solvent, pickling, washing with water, filtering, and drying to remove the solvent and by-products of the graphene crude product in the suspension solution, thereby obtaining high-purity graphene;

the polyhalogenated hydrocarbon is: tetrabromo (fluoro, chloro or iodo) ethylene, hexabromo (fluoro, chloro or iodo) 1, 3-butadiene; hexabromo (fluoro, chloro or iodo) benzene, trichlorotribromo (fluoro or iodo) benzene; octachloro (fluoro, bromo or iodo) naphthalene, tetrachlorotetrabromo (fluoro or iodo) naphthalene; decachloro (fluoro, bromo or iodo) anthracene (phenanthrene), hexabromo (iodo) tetrachloranthracene (phenanthrene), hexachlorotetrabromoanthracene (phenanthrene); decachloro (fluoro, bromo, iodo) pyrene, hexabromotetrachloropyrene, tetrabromohexachloropyrene; perchloro (fluorine, bromine, iodine) biphenyl, perchloro (bromine, iodine) terphenyl, polychlorine (bromine, iodine) benzanthracene (pyrene);

the benign solvent is selected from a solvent which does not react with the raw materials of alkali metal or alkaline earth metal and polyhalogenated hydrocarbon, and is one or a mixture of more of (methyl, ethyl) tetrahydrofuran, dioxane, (triscondensation, disunion, monocondensation) ethylene (propylene, butylene) glycol dimethyl (ethylene, propylene, butylene, benzene) ether, diphenyl ether, dimethyl (ethylene, propylene, butylene) phenyl ether and benzyl ether.

2. The preparation method according to claim 1, wherein the alkali metal or alkaline earth metal is selected from one or more of active metals of lithium, sodium, potassium, magnesium, calcium, strontium and barium.

3. The method according to claim 1, wherein the alcohol, water or acid used for reducing or eliminating the residual alkali metal or alkaline earth metal is one or more selected from the group consisting of methanol, ethanol, propanol, isopropanol, n-butanol, ethylene glycol, propylene glycol, glycerol, water, hydrochloric acid, hydrobromic acid, hydroiodic acid, hydrofluoric acid, sulfuric acid, phosphoric acid, nitric acid, oxalic acid, formic acid and acetic acid.

4. The method of claim 1, wherein the organic solvent is one or more selected from petroleum ether, acetone, diethyl ether, ethanol, methanol, DMAc and DMF, and is used for washing residual reaction solvent, the washing acid used for acid washing is one or more selected from hydrochloric acid, hydrobromic acid, hydroiodic acid, hydrofluoric acid, sulfuric acid, phosphoric acid, nitric acid, oxalic acid, formic acid and acetic acid, and the water washing is performed by washing residual salt with deionized water.

5. The method of claim 1, wherein the coupling reaction temperature is from 30 ℃ to 180 ℃.

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