KR101488410B1 - Method for manufacturing reduced graphite oxide and reduced graphite oxide using thereof - Google Patents

Abstract

A process for producing reduced graphite oxide is provided. The method for producing reduced graphite oxide according to an embodiment of the present invention includes the steps of providing graphite oxide, preparing a first mixed solution by mixing the graphite oxide with a dispersion containing an organic alkali metal compound or a derivative thereof, Stirring and filtering the first mixture liquid to produce a second mixture, and drying the second mixture to produce reduced graphite oxide.
According to the embodiments of the present invention, graphite oxide can be rapidly reduced using an organic alkali metal compound and a derivative thereof, which are new graphite oxide reducing agents, and production efficiency is high. In particular, unlike the conventional method, which can be performed at a high temperature, it is possible to provide reduced graphite oxide in a short time at a room temperature. In addition to showing an improved dispersibility, this characteristic can be controlled through a simple modification of the synthesis process.

Description

METHOD FOR MANUFACTURING REDUCED GRAPHITE OXIDE AND REDUCED GRAPHITE OXIDE USING THEREOF FIELD OF THE INVENTION [0001] The present invention relates to a method for producing reduced graphite oxide,

The present invention relates to a process for producing a reduced graphite oxide and a reduced graphite oxide produced therefrom, and more particularly to a process for producing reduced graphite oxide by using an organic alkali metal compound and / or a derivative thereof as a reducing agent, And a reduced graphite oxide prepared by using the organic alkali metal compound and / or a derivative thereof capable of improving the dispersibility and the dispersibility of the reduced graphite oxide.

Graphene is a honeycomb monolayer composed of sp2 hybrid carbons and has excellent mechanical, thermal and electrical properties as well as light weight, and has been found in various fields such as batteries, supercapacitors, sensors, fuel cells, Have been actively studied as applied materials to The synthesis of graphene can be divided into mechanical peeling, chemical vapor deposition (CVD), epitaxial growth, and chemical reduction, which can be mass-produced. And the advantage of application through functionalization, chemical reduction method is widely used for graphene synthesis.

Graphene production through chemical reduction is achieved through the reduction of graphite oxide, and a reducing agent is essential in the reduction process. Various reducing agents have been studied including hydrazine, sodium borohydride (NaBH4), hydrohalic acid, hydroquinone, iron nanoparticles and the like.

However, the production of graphene through conventional reducing agents is costly in terms of cost. In addition, it is pointed out that it is difficult to solve the problem of acting as a defect in the application of the material according to the reducing agent and the problem of incomplete reduction of the hydroxyl group (hydroxyl group). [Carbon 2007,45, 1558 .; Adv. Func. September 2009, 19, 1987; Nat. Chem.2009, 1, 403.].

Specifically, various reducing agents have been studied including hydrazine, sodium borohydride (NaBH ₄ ), hydrohalic acid, hydroquinone, iron nanoparticles, etc. However, Respectively. More specifically, most of the reducing agents are 100? Or higher, is used as a reducing condition, but it takes a long time from several hours to one day. To overcome these limitations, there have been studies of reduction temperatures near room temperature, but the long reduction times from days to a week still have a negative impact on productivity.

In addition, the degradation of the dispersibility due to the hydrophobicity of the reduced graphite oxide has been a problem in the application process of the reduced graphite oxide. Covalent functionalization and noncovalent functionalization have been mainly studied in order to improve the dispersibility of the reduced graphite oxide. However, this necessitates additives such as a dispersion stabilizer, and these cause degradation of the reduced graphite oxide There is a drawback that it can be taken, and research on the improvement of dispersibility through chemical modification method is needed without additional additives.

Therefore, there is an urgent need for a method for solving the problems of existing reducing agents in the production of graphene through a chemical reduction method.

The present invention has been made based on these points, and an object of the present invention is to provide a method for producing graphene using a novel reducing agent capable of quickly obtaining a large amount of reduced graphite oxide, and a method for producing reduced graphite oxide .

Another object of the present invention is to provide a method for producing reduced graphite oxide using an organic alkali metal compound and / or a derivative thereof capable of chemically reducing graphite oxide and rapidly and easily producing a reduced amount of graphite oxide, And to provide a reduced graphite oxide produced therefrom.

Another problem to be solved by the present invention is to provide a method for producing graphene having improved dispersibility by simple modification of the washing step in the manufacturing process and a reduced graphite oxide produced thereby.

The problems of the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

In order to solve this problem, a method of manufacturing a graphene according to an embodiment of the present invention includes the steps of providing graphite oxide, mixing the graphite oxide with a dispersion containing an organic alkali metal compound or a derivative thereof, , Stirring and filtering the first mixture liquid to produce a second mixture, and drying the second mixture to produce reduced graphite oxide.

According to another embodiment of the present invention, there is provided a graphene manufacturing method comprising the steps of providing graphite oxide, mixing a graphite oxide with a dispersion containing an organic alkali metal compound or a derivative thereof to prepare a first mixed solution, Mixing and washing the mixed liquid to prepare a second mixture, washing the second mixture, and drying the second mixture to produce a reduced graphite oxide.

A more detailed example of embodiments of the present invention will be described later in the embodiment section with reference to the drawings.

According to the embodiments of the present invention, it is possible to rapidly reduce the graphite oxide using an organic alkali metal compound and a derivative thereof, which is a novel graphite oxide reducing agent, thereby providing a large amount of reduced graphite oxide (graphene) .

In addition, since the produced reduced graphite oxide has high production efficiency, it can be used at a low cost in a wide range of fields such as an electrode material for a lithium ion battery, a supercapacitor electrode material, a solar cell, a gas adsorption and storage material, a sensor, It is possible.

In particular, unlike the conventional method which has been carried out at a high temperature of 100 ° C or higher, reduced graphite oxide can be provided in a short time at a room temperature, and not only the improved dispersibility can be obtained, but also this characteristic can be controlled through a simple modification of the synthesis process.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the specification.

FIG. 1A is a photograph of the reduced graphite oxide prepared according to Example 1 of the present invention after 24 hours of dispersing in distilled water. FIG.
FIG. 1B is a photograph of the reduced graphite oxide prepared according to Example 2 of the present invention after 24 hours from dispersing in distilled water. FIG.
2 is an X-ray diffraction pattern of graphite oxide and reduced graphite oxide prepared according to Example 1 of the present invention.
FIG. 3 is a microstructure photograph of the reduced graphite oxide prepared according to Example 1 of the present invention, wherein (a) is a SEM photograph of reduced graphite oxide and (b) is a TEM photograph of reduced graphite oxide.
4 is a Raman spectrum of graphite oxide and reduced graphite oxide prepared according to Example 1 of the present invention.
5A is an X-ray photoelectron spectroscopy (XPS) spectrum of graphite oxide and reduced graphite oxide prepared according to Example 1 of the present invention.
FIG. 5B is a table showing the XPS C1s spectra of graphite oxide and reduced graphite oxide prepared according to Example 2 of the present invention by means of curve-fitting.
FIG. 6A is a photograph of the reduced graphite oxide prepared according to the first embodiment of the present invention, after 24 hours after dispersion in distilled water and before dispersion. FIG.
FIG. 6B is a photograph of the reduced graphite oxide prepared according to Example 2 of the present invention, obtained 24 hours after the dispersion of graphite oxide in distilled water.
FIG. 6C is a photograph of the reduced graphite oxide prepared according to Comparative Example 1 of the present invention, obtained 24 hours after the dispersion graphite oxide was dispersed in distilled water.
FIG. 6D is a photograph of the reduced graphite oxide prepared according to Comparative Example 2 of the present invention, obtained 24 hours after dispersed in distilled water.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. &Quot; and / or "include each and every combination of one or more of the mentioned items. ≪ RTI ID = 0.0 >

Although the first, second, etc. are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, it goes without saying that the first component mentioned below may be the second component within the technical scope of the present invention.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. The terms " comprises "and / or" comprising "used in the specification do not exclude the presence or addition of one or more other elements in addition to the stated element.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

Hereinafter, a method of manufacturing graphene according to embodiments of the present invention will be described with reference to FIGS. 1 to 6D.

A method of manufacturing graphene according to an embodiment of the present invention comprises reacting graphite oxide with an organic alkali metal compound as a reducing agent and / or a derivative thereof to finally produce reduced graphite oxide (graphene).

As used herein, the term "graphite oxide reducing agent" may refer to a material used to reduce graphite oxide or a combination thereof, and the material used to reduce graphite oxide may include, for example, There are daily doses to assist with the reducing agent.

Graphite oxide oxidized graphite is a modified Hummer? method [Chem. Mater. 1999, 11, 771.]. The step of providing graphite oxide may be formed by oxidizing graphite or expanded graphite.

The organic alkali metal compound and / or the derivative thereof to be used as a reducing agent can be prepared by dissolving an organic compound in an anhydrous solvent, adding an appropriate amount of an alkali metal or a substance containing it, and reacting. The organic compound used is preferably a multi-aromatic compound, but is not limited to any substance capable of forming an organic alkali metal compound and / or a derivative thereof.

For example, the organic alkali metal compound may include alkali metals Li, Na, K, rb, cesium, and the like, ), Anthracene, chrysene, corannulene, phenanthrene, triphenylene, benzopyrene, coronene, tetracene, pentaerythritol, And may further include at least one of pentacene, ovalene, carbazole, fluorenone, benzophenone, and anthraquinone.

In order to reduce the graphite oxide using the organic alkali metal compound and / or its derivative obtained through the above process, water-bathed sonication is performed at 0.1 to 10 mg / ml in the anhydrous solvent of the graphite oxide, For 0.1 to 48 hours, but it is not limited to any method capable of achieving the above object while blocking moisture and air contact. In addition to water-bathed sonication, either ultrasonication or homogenizer may be performed, or other methods of dispersion may be used.

The anhydrous solvent may be, for example, N, N'-dimethylformamide, N, N'-diethylformamide, t-butylformamide, , Anhydrous t-butylacetamide, tetrahydrofuran, dioxane, N-methyl-2-pyrrolidone (NMP), anhydrous tetrahydrofuran, Ethylene glycol, anhydrous diethylene glycol, diethyl ether, anhydrous tri- or tetraethylene glycol dimethyl ether, anhydrous acetonitrile, It is preferable to use anhydrous 1,2-dimethoxyethane (DME), tetramethylene sulfone, dimethyl sulfone, diphenyl sulfone, anhydrous tetramethylene sulfoxide tetramethylene sulf but are not limited to, one or more of oxide: TMSO, dimethyl sulfoxide (DMSO), and anhydrous diphenyl sulfoxide.

An organic alkali metal compound and / or a derivative thereof is added to a graphite oxide dispersion. It is preferable to stir at a rate of 10 rpm to 10000 rpm at 10 to 50 ° C for 1 minute to 1440 minutes, but it is applicable if the temperature, the stirring speed, and the time at which the mixed liquid of the same characteristics can be obtained.

The sufficiently stirred mixture is filtered through filtration, and the filtrate is washed 1 to 30 times with washing with a solvent, tetrahydrofuran (THF), water or methanol. Washing using a solvent is carried out for the purpose of removing unreacted materials, so that any solvent that can perform this purpose without modification of the obtained material can be used.

Washing using methanol or water is carried out for the purpose of removing impurities including alkali metal derivatives and obtaining reduced graphite oxide close to graphene, but in order to improve dispersibility, it is preferable to use a solvent used without methanol or water .

It is preferable to dry the obtained material at a temperature of 20 to 90 DEG C for 1 to 60 hours in a vacuum of 10 ^-3 Torr or less or in a vacuum oven of 1 atm. However, drying is performed without modifying the obtained reduced graphite oxide Anything you can use is possible.

Thereafter, it is preferable to finally dry using a low-activity or inert gas such as nitrogen, argon, neon, krypton or xenon. Reduced graphite oxide can be obtained through the above process.

In the present invention, X-ray diffraction (X-ray diffraction) was used for structural analysis and XPS was used for analyzing functional groups. Raman spectroscopy was used to observe structural changes, and scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for microstructure analysis.

The use of the novel graphite oxide reducing agent as evidenced by the present invention makes it possible to easily obtain a reduced amount of high quality graphite oxide in a short time at room temperature.

In addition, the method of the present invention enables control of dispersion stability, so that reduced graphite having improved dispersion can be obtained.

The reduced graphite oxide prepared according to the method of the present invention can be applied to a variety of materials such as electrodes for lithium ion batteries, supercapacitors, solar cells, gas adsorption and storage agents, sensors, organic dye adsorption and storage agents, memory materials, It is available.

The present invention will be further illustrated by the following embodiments, which do not limit the scope of the present invention.

Example  One

Graphite oxide oxidized graphite is a modified Hummer? method [Chem. Mater. 1999, 11, 771.].

Lithium naphthalenide to be used as a reducing agent was prepared by dissolving 0.1 mol of naphthalene in 1 L of anhydrous tetrahydrofuran and then adding an appropriate amount of lithium [Angew. Chem. Int. Ed., 2011, 50, 491.].

The process for reducing graphite oxide using lithium naphthalenide obtained through the above process is as follows. After redispersing the graphite oxide through an aqueous-tetrahydrofuran water-bathed sonication, the lithium naphthalenide is added to the graphite oxide dispersion. After stirring at room temperature for 10 minutes, the mixture is filtered through filtration and washing with methanol or water can be repeated.

The obtained material is dried in a vacuum oven at a temperature of 60 占 폚 for 24 hours to finally obtain a reduced graphite oxide.

Example  2

Graphite oxide oxidized graphite is a modified Hummer? method [Chem. Mater. 1999, 11, 771.].

Lithium naphthalenide to be used as a reducing agent was prepared by dissolving 0.1 mol of naphthalene in 1 L of anhydrous tetrahydrofuran and then adding an appropriate amount of lithium [Angew. Chem. Int. Ed., 2011, 50, 491.].

The process for reducing graphite oxide using lithium naphthalenide obtained through the above process is as follows. The graphite oxide is redispersed through water-bathed sonication in anhydrous tetrahydrofuran. Lithium naphthalenide is added to the graphite oxide dispersion. After stirring at room temperature, the mixture is filtered through filtration and washed repeatedly with tetrahydrofuran. The obtained material is dried in a vacuum oven at a temperature of 60 占 폚 for 24 hours to finally obtain a reduced graphite oxide.

Comparative Example  One

Graphite oxide oxidized graphite is a modified Hummer? method [Chem. Mater. 1999, 11, 771.].

Preparation of reduced graphite oxide with hydrazine was prepared according to the following article [Carbon 2007, 45, 1558.].

Comparative Example  2

Graphite oxide oxidized graphite is a modified Hummer? method [Chem. Mater. 1999, 11, 771.].

Preparation of reduced graphite oxide using sodium borohydride was prepared according to the following article [Nat. Chem.2009, 1, 403.].

Experimental Example  1 - Experiment of dispersion stability of aqueous solution

Figs. 1A and 1B are photographs obtained after 24 hours from the dispersion of reduced graphite oxide in distilled water according to Example 1 and Example 2 of the present invention, respectively. In the case of the reduced graphite oxide prepared according to Example 2 (FIG. 1B), it can be confirmed that the stability of dispersion through the chemical control method is improved due to the residual alkali metal.

Experimental Example  2 - X-ray diffraction  (X- ray Diffraction ) analysis

FIG. 2 shows data obtained by X-ray diffraction analysis of graphite oxide and reduced graphite oxide prepared according to Example 1 of the present invention. The reaction time of 10 minutes shows that the reduction is above a certain level.

Experimental Example  3 - Microscope ( SEM , TEM ) analysis

3 shows microstructure-related data according to Embodiment 1 of the present invention. 3 (a) is an SEM photograph of reduced graphite oxide, and (b) is a TEM photograph of reduced graphite oxide. Through the microstructure photograph and the SAED (Selected Area Electron Diffraction) pattern, it is confirmed that the use of an organic alkali metal compound such as lithium naphthalenide and its derivative forms a reduced monolayer graphite oxide within 10 minutes at room temperature.

Experimental Example  4 - Raman  analysis

4 shows Raman analysis results of graphite oxide and reduced graphite oxide produced according to Example 1 of the present invention. In the case of the reduced graphite oxide, since the intensity ratio (I _D / I _G ) is larger than that of graphite oxide, it can be seen that the size of the graphene-like domain is small, but more.

Experimental Example  5 - XPS (X- ray Photoelectron Spectroscopy ) analysis

FIG. 5A shows X-ray photoelectron spectroscopy (XPS) analysis results of graphite oxide and reduced graphite oxide prepared according to Example 1 of the present invention. FIG. 5B is a graph showing the results of XPS analysis of graphite oxide and reduced graphite Oxides XPS C1s spectra were quantitatively analyzed by curve-fitting. 5A, it can be confirmed that the functional groups containing oxygen in the reduced graphite oxide are commonly decreased as compared with graphite oxide.

Experimental Example  6 - Dispersion stability test on major solvents

6A to 6D are photographs obtained after 24 hours from the reduction graphite oxide before and after dispersion in distilled water according to Example 1, Example 2, Comparative Example 1 and Comparative Example 2 of the present invention, respectively. In the case of the reduced graphite oxide produced according to Example 1, the dispersion stability was observed to be low similarly to the reduced graphite oxide prepared according to Comparative Example 1 and Comparative Example 2.

However, the reduced graphite oxide prepared according to Example 2, which changed in the washing step, exhibited a more stable dispersion regardless of the solvent type. Accordingly, the production method of the present invention confirms that a reduced graphite oxide having improved dispersion degree is obtained through a comparatively easy dispersion control method.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. But is not limited to the form.

Claims (12)

delete Providing a graphite oxide;
Preparing a first mixed solution by mixing the graphite oxide with a dispersion containing an organic alkali metal compound or a derivative thereof;
Stirring and filtering the first mixed solution to prepare a second mixture in which a part or the whole of the first mixed solution is reduced;
Washing the second mixture with tetrahydrofuran (THF); And
And drying the second mixture to produce a reduced graphite oxide,
The step of washing the second mixture comprises:
Wherein the graphite oxide is washed by repeating 2 to 30 times at intervals of 10 minutes to 48 hours. 3. The method of claim 2,
Wherein the step of providing the graphite oxide comprises:
Wherein the reduced graphite oxide is formed by oxidizing graphite or expanded graphite. 3. The method of claim 2,
Wherein the step of preparing the first mixed solution comprises:
And mixing the graphite oxide with the second solvent at 0.1 mg / ml to 10 mg / ml. 5. The method of claim 4,
The second solvent may be, for example,
N, N'-diethylformamide, t-butylformamide, anhydrous acetamide, anhydrous t-butylacetamide (N, N'-dimethylformamide, t-butylacetamide, tetrahydrofuran, dioxane, N-methyl-2-pyrrolidone (NMP), anhydrous ethylene glycol, Diethylene glycol, diethyl ether, anhydrous tri- or tetraethylene glycol dimethyl ether, anhydrous acetonitrile, anhydrous 1,2-dimethoxyethane (DMSO), 1,2-dimethoxyethane (DME), tetramethylene sulfone, dimethyl sulfone, diphenyl sulfone, tetramethylene sulfoxide (TMSO) Sake foxy (Dimethyl sulfoxide: DMSO),, method of producing a reduction of graphite oxide comprising at least one of anhydrous diphenyl sulfoxide (diphenyl sulfoxide). 3. The method of claim 2,
Wherein the step of preparing the first mixture comprises:
Performing one of water-bathed sonication, ultrasonication, and homogenizer in the first mixture,
And the mixing time is 1 second to 480 hours. 3. The method of claim 2,
Wherein the step of preparing the second mixture comprises:
The first mixture further comprises one or more of stirring or water-bathed sonication, ultrasonication, homogenizer at a speed of 10 rpm to 10000 rpm at 10 ° C to 50 ° C, , A process for producing reduced graphite oxide. 3. The method of claim 2,
The organic alkali metal compound may be, for example,
And at least one of lithium (Li), sodium (Na), potassium (K), rubidium (Rb) and cesium (Cs)
The organic alkyl metal compound may be, for example,
Examples of the naphthalene, anthracene, chrysene, corannulene, phenanthrene, triphenylene, benzopyrene, coronene, tetracene, ), A method for producing reduced graphite oxide comprising at least one of pentacene, ovalene, carbazole, fluorenone, benzophenone, and anthraquinone . delete delete 3. The method of claim 2,
Wherein the step of preparing the reduced graphite oxide comprises:
And drying in an oven at a vacuum of 10 ^-3 Torr or less or 1 atm under a temperature of 20 ° C to 90 ° C for 1 hour to 60 hours. delete

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