KR101206741B1 - Graphene forming method by graphite intercalation compounds made by salts - Google Patents

Abstract

The present invention relates to a method for preparing graphite intercalation compound (GIC) and producing graphene using the same. The present invention comprises the steps of (a) obtaining an alkali metal or alkali metal ion or alkaline earth metal or alkaline earth metal ion from an alkali metal salt or alkaline earth metal salt; (b) forming a graphite interlayer compound using the alkali metal or alkali metal ions or alkaline earth metal or alkaline earth metal ions; And (c) dispersing the graphite interlayer compound to obtain graphene. The present invention can easily produce a graphite interlayer compound at a low price by using a cheap and safe salt, it is possible to lower the production cost of the graphene by obtaining the graphene through it, it is easy to mass-produce the graphene.

Description

Graphene manufacturing method by preparing graphite intercalation compound using salt {Graphene forming method by graphite intercalation compounds made by salts}

The present invention relates to a graphene (graphene) manufacturing method, and more particularly to a method for producing a graphite interlayer compound and a single layer or several layers of graphene using the same.

Indium Tin Oxide (ITO) electrodes, which are used as electrode materials for plastic substrates, are more than 1000 times higher in sheet resistance when wheeled, and are actually flexible due to the brittle nature of ITO itself and the difference in thermal expansion coefficient between plastic substrates. There are many problems when applied to electronic devices. Currently, conductive polymers, carbon nanotubes, and carbon nanofibers are being considered as conductive materials that can replace ITO. Among them, carbon nanotubes, which are excellent in conductivity and adhesion to a substrate, and which are mechanically and thermally stable, are next-generation electrode materials. Is in the spotlight.

However, carbon nanotubes have a problem in that when applied to devices as a single functional element, linear I / O currents are low, contact area is small, and linear carbon nanotubes are synthesized at desired positions. Graphene is a perfect two-dimensional carbon nanoelectronic material that can solve this problem.

Graphene refers to a planar two-dimensional carbon structure that forms sp2 bonds, and has a high physical and chemical stability. At room temperature, electrons can be moved 100 times faster than silicon and 100 times more current per unit area than copper. In addition, the thermal conductivity is more than two times higher than diamond, the mechanical strength is more than 200 times stronger than steel and has transparency. In addition, the spatial clearance of the hexagonal honeycomb structure, where carbon is connected like a net, creates elasticity and does not lose electrical conductivity even when stretched or folded. Such unusual structure and physical properties of graphene can replace ITO, the main material of current transparent electrodes, and can replace silicon, the main material of semiconductors.

In order to apply the graphene having excellent characteristics to the flexible electronic device, it is necessary to mass produce a large area of graphene having a single layer of high quality and to manufacture the graphene at a low temperature. In addition, to be commercialized, it must be competitive in price and secured in process safety.

Current methods for preparing graphene include mechanical, epitaxy, thermal expansion, gas phase, chemical vapor deposition (CVD), graphene redox, and graphite intercalation compounds. Fin oxidation-reduction methods are used for graphene production.

The mechanical method is to attach a scotch tape to a graphite sample and then remove it to obtain graphene in the form of a sheet separated from graphite on the surface of the scotch tape. In this case, the peeled off graphene sheet has a constant number of layers, and its shape is not constant due to the tearing of paper. Moreover, there is a disadvantage that it is extremely difficult to obtain a large amount of graphene sheets in large areas.

The epitaxy method is a method of growing a graphene layer on a single crystal silicon carbide (SiC) substrate, and the thermal expansion method is a graphene is prepared by applying a heat of 1000 ° C. or more to graphite oxide to remove oxides and separating the layers at the same time. It is a way. In the gas phase method, argon gas and ethanol aerosol are injected into a microplasma reactor to form an argon plasma to induce evaporation and decomposition of ethanol, and when the plasma is stopped, graphene of a solid material is produced.

The CVD method is a method of depositing a catalyst metal on a substrate to form a thin metal film, and then flowing a gas containing carbon, argon, and hydrogen together at a high temperature of 800 ° C. or higher to obtain graphene formed on the metal film. However, the process temperature is very high, the graphene may be damaged during the catalyst removal process, disadvantageous in terms of large area and price.

Oxidizing, dispersing, and reducing graphite to obtain graphene is one of the most commonly used methods. However, oxygen (O) atoms are not completely removed in the reducing process.

1 and 2 show the characteristics of graphene made by the conventional redox method. 1 is a result of X-ray photoelectron spectroscopy (XPS) of redox graphene, (a) before reducing graphene oxide, (b) after reducing, and (c) until heat treatment after reduction. A rough case is indicated. As shown in FIG. 1, even after the reduction and heat treatment of graphene oxide, a significant amount (more than 20%) of oxygen atoms remains without being removed (Nature Nanotechnology 3, 270 (2008)).

2 is a graph showing the relationship between the sheet resistance and transmittance of the graphene. The more oxygen atoms are removed, the more the permeability increases, but the surface resistance also increases. In order to apply graphene as a transparent conductive film, the permeability and the sheet resistance are important, so there is a problem when oxygen atoms are not removed.

The current graphite intercalation compound method is to insert a metal between graphite interlayers. The interlayer spacing of the original graphite is 3.35 Å, but when the alkali metal or alkaline earth metal ions are inserted between the graphite layers, the interlayer spacing is widened. At this time, the interval between the ions located at the bottom of the periodic table, that is, the atomic radius is larger, becomes larger.

However, conventionally, graphite intercalation compounds have been prepared by directly using metals to insert alkali metal ions or alkaline earth metal ions between graphite layers, melting the metals themselves or metals in an appropriate organic solvent, and then reacting with graphite. . Alkali metals and alkaline earth metals are elements of Groups 1 and 2 of the periodic table, which are very reactive and therefore impossible to process in an oxygen atmosphere. They are extremely explosive and difficult to handle. In addition, the price of the metal itself is very expensive, the price of graphene is very high.

In the production of graphite intercalation compounds, when alkali metal ions or alkaline earth metal ions and molecules such as tetrahydrofuran (THF) are inserted together between graphite layers (called cointercalation), the gap between the graphite layers becomes wider. This can make dispersion into graphene easier. Table 1 shows that the spacing when metal ions are intercalated between graphite layers increases and that spacing increases further when THF is added.

The problem to be solved by the present invention is to provide a graphene manufacturing method that can proceed to a safe process at a low temperature in order to mass-produce a large area of graphene having a high quality.

In order to achieve the above object, the present invention comprises the steps of (a) obtaining an alkali metal or alkali metal ion or alkaline earth metal or alkaline earth metal ion from an alkali metal salt or alkaline earth metal salt; (b) forming a graphite interlayer compound using the alkali metal or alkali metal ions or alkaline earth metal or alkaline earth metal ions; And (c) dispersing the graphite interlayer compound to obtain graphene.

The method may further include removing by-products of the forming of the graphite interlayer compound.

The alkali metal salt or alkaline earth metal salt is preferably a metal halide, and when two or more kinds of alkali metal salts or alkaline earth metal salts are used, they are mixed in a eutectic molar ratio.

The present invention does not use metal directly for the production of graphite intercalation compounds, but uses cheap and safe salts. Thus, existing expensive, complex and dangerous processes for the production of graphite intercalation compounds can be converted into cheap, simple and safe processes. The invention also proceeds at low temperatures.

Accordingly, the price of graphene can be lowered, and the graphene manufacturing process can be easily performed, thereby enabling mass synthesis of graphene. Through this, large-scale graphene with high quality can be mass-produced, and the possibility of commercialization can be suggested.

1 is an XPS (X-ray Photoelectron Spectroscopy) result of graphene prepared by a conventional redox method.
FIG. 2 is a graph showing a relationship between sheet resistance and transmittance of graphene made through a conventional redox method.
3 is a flowchart of a graphene manufacturing method according to the present invention, Figure 4 is a schematic diagram according to the process according to it.
5 is a state diagram of KI and KOH used in the first experimental example of the present invention.
Figure 6 (a) is the first KI and KOH and HOPG (Highly Oriented Pyrolytic Graphite) in the first experimental example of the encapsulated container when opened and heated, Figure 6 (b) is the KI and KOH in THF is also the result when put together.
Figure 7 is the TGA results of the K-graphite interlayer compound made through KI-KOH conditions in the first experimental example of the present invention.
8 is a state diagram of KI and KCl used in the second experimental example of the present invention.
Figure 9 (a) is a state dispersed in dichlorobenzene (dichlorobenzene: DCB) after the hot process in the second experimental example of the present invention, Figure 9 (b) is a state when mixed with ethanol after the dispersion of DCB.
10 is a Raman spectroscopy result of the graphene prepared according to the second experimental example of the present invention.
11 and 12 are Raman spectroscopy results according to a comparative example.
13 is a TEM (Transmission Electron Microscopy) photograph of the graphene prepared by the second experimental example of the present invention.
14 is an XPS analysis result of graphene prepared as a second experimental example of the present invention and graphite as a raw material of this process.
15 is a schematic diagram of a graphene manufacturing method according to a third experimental example of the present invention.
FIG. 16 is a gas chromatography / mass spectroscopy result for confirming that 1-iodine-2-chloro-benzene is formed through the reaction of KI and DCB in the third experimental example of the present invention. .
17 is a result of checking the change in pH while adding distilled water to confirm whether Cl ₂ is generated through the reaction of KI and DCB in the third experimental example of the present invention.
18 is a high magnification TEM (HRTEM) photograph showing the edge of the graphene prepared by the third experimental example of the present invention and a comparative example (multilayer graphene).
FIG. 19 (a) is a reference for informing the diffraction pattern by the (100) plane and the (110) plane, and FIG. 19 (b) is manufactured through the third experimental example of the present invention. It is a diffraction pattern of graphene, and FIG. 19C shows a diffraction pattern of multilayer graphene as a comparative example.
Figure 20 (a) is a Raman spectroscopic 2D peak shape of the graphene prepared by the third experimental example of the present invention, Figure 20 (b) attempts to analyze the Raman mapping (Raman mapping) of two points of 5um ㅧ 3um size. According to the shape of the 2D peak was investigated the distribution and proportion of the layer.
Figure 21 shows the Raman spectroscopy results of the graphene prepared according to the third experimental example of the present invention.
22 is an XPS analysis result of graphene prepared by the third experimental example of the present invention.
23 is an XPS analysis result for confirming the presence of K, Cl, I in the graphene prepared by the third experimental example of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Accordingly, the shape of the elements in the drawings and the like are exaggerated to emphasize a clearer description.

3 is a flowchart of a graphene manufacturing method according to the present invention, Figure 4 is a schematic diagram according to the process according to it.

First, according to step s1 of FIG. 3, alkali metal or alkali metal ions or alkaline earth metal or alkaline earth metal ions are obtained from alkali metal salts or alkaline earth metal salts. The type of salt does not need to be greatly limited, but it is preferable to select a cheap, safe and easy to handle. Particularly preferred salts are metal halides.

Alkali metal ions or alkaline earth metals from alkali metal salts having alkali metals (Li, Na, K, Rb, Cs) as cations or alkaline earth metal salts having alkaline earth metals (Be, Mg, Ca, Sr, Ba) as cations Two methods are available for obtaining ions.

One way of obtaining alkali metal ions or alkaline earth metal ions from alkali metal salts or alkaline earth metal salts is to heat the alkali metal salts or alkaline earth metal salts together above the melting point. In this case, when two or more salts are put together, the melting point is lowered at a specific mixing molar ratio of the two or more salts. The molar ratio and temperature point at this time are called eutectic points, which can be seen from the phase diagrams of two or more salts, and Table 2 shows the eutectic points for some salts.

Another method of obtaining alkali metal ions or alkaline earth metal ions from an alkali metal salt or alkaline earth metal salt is to add a solvent to dissolve the salt. Compared to the first method, the process temperature does not have to be raised to the melting point of the salt, which further lowers the process temperature.

In order to obtain alkali metal ions or alkaline earth metal ions from alkali metal or alkaline earth metal salts, salt mixtures comprising at least two salts are preferably used. At this time, like KI and KCl, the cations may be the same and the anions may be different salts. Like KI and LiI, the cations may be different but the same anions may be used. In addition, it is possible to have different anions and cations such as KI and LiCl. In other words, any kind may be used as long as the salt contains an alkali metal or an alkaline earth metal in the cation.

Salt mixtures comprising at least two alkali metal or alkaline earth metal salts are prepared into a mixture by mixing with graphite. The mixture is then heated above the eutectic point of the salt mixture to melt the salt mixture, or a solvent is added to the mixture to dissolve the salt mixture.

On the other hand, when the alkali metal salt or alkaline earth metal salt is dissolved in a solvent, an alkali metal or alkaline earth metal can be obtained. This method is to obtain alkali metal or alkaline earth metal through chemical reaction between alkali metal or alkaline earth metal salt and solvent.

Next, referring to step s2 of FIG. 3, the graphite interlayer compound is formed using the alkali metal or alkali metal ion or alkaline earth metal or alkaline earth metal ion obtained in step s1. At this time, the addition of at least one of THF, ammonia, toluene, benzene, dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) further increases the distance between the graphite layers, making graphene more easily. You can get it.

The formation of alkali metal (or alkaline earth metal) -graphite intercalation compounds is a compound that spontaneously forms as an alkali metal or alkali metal ion or alkaline earth metal or alkaline earth metal ion intercalates into the interlayer of graphite. The diffusion distance may be calculated through diffusivity of alkali metal or alkali metal ions or alkaline earth metal or alkaline earth metal ions, thereby predicting the average size of graphene. It is also possible to increase the average size of graphene by increasing the diffusion coefficient.

By the way, the salt is present as a cation and an anion in the state of melting above the melting point heating or solvent, and is electrically neutral. Although the reaction in which alkali metal ions or alkaline earth metal ions are intercalated between graphite layers is a spontaneous reaction, alkali metal ions or alkaline earth metal ions cannot be intercalated between graphite layers while breaking the electric neutral state.

Therefore, in the present invention, two or more salts are used to react the anions of the salt mixture. For example, when KI and KCl are mixed as salts, I ^-of KI and Cl ^- of KCl meet to form a compound called ICl. ICl is a unique compound in which two substances with anionic tendencies meet to form a compound. As the anions react as described above, cations are inserted between the graphite layers. In other words, while making ICl, K ⁺ is intercalated between graphite layers. At this time, K ⁺ is inserted into the graphite layer while changing to K. Intercalated cations (alkali metal or alkaline earth metal atoms) can increase the spacing between the layers of graphite to separate the graphite layers. After forming the graphite intercalation compound, further by-products such as ICl may be removed.

When the graphite intercalation compound is formed using an alkali metal or alkaline earth metal obtained through the reaction of a salt with a solvent, the alkali metal or alkaline earth metal is intercalated into the graphite interlayer.

Next, as in step s3 of Figure 3, the graphite interlayer compound is dispersed to obtain graphene. The dispersing process is to remove the alkali metal or alkaline earth metal in atomic form intercalated from the graphite interlayer compound.

Referring to FIG. 4, which is a process schematic diagram, first, graphite 10 as a raw material is composed of several layers 10a, 10b, 10c,... When the alkali metal or alkali metal ion or alkaline earth metal or alkaline earth metal ion 20 obtained from the alkali metal salt or alkaline earth metal salt in step s1 is inserted between the graphite layers 10a, 10b, 10c, ... according to step s2, Alkali metal or alkaline earth metal as it is, alkali metal ions or alkaline earth metal ions can be converted to an alkali metal or alkaline earth metal to form a graphite intercalation compound (GIC) 30 as shown in Figure 4 (b).

Next, the step S3 is performed to remove the alkali metal or alkaline earth metal 20 interposed between the GIC 30 layers. When alcohols or a suitable solvent having a hydroxyl group (-OH) are applied to the GIC 30 above, the alkali metal or the alkaline earth metal 20 escapes, thereby forming the graphite 10 in various layers 10a, 10b, 10c,. ..) Monolayer or multilayered graphite is graphene.

Hereinafter, specific experimental examples will be described.

Experimental Example

In this experiment, K ions, which are alkali metals, were selected as ions to be inserted between the graphite layers, and a salt mixture of KI and KOH was used as an alkali metal salt to provide K ions.

5 is a state diagram of KI and KOH, when two or more salts are mixed at a specific molar ratio, it can be seen that the melting point is lowered. Since KI and KOH have a low eutectic temperature of 250 ° C. as shown in FIG. 5, when KI and KOH are heated to 250 ° C. or higher using KI and KOH at a molar ratio of eutectic point, graphite may be dispersed without additional solvent.

Figure 6 (a) is when the KI and KOH and HOPG (Highly Oriented Pyrolytic Graphite) pieces are put in an encapsulated container and heated to 250 ° C. and then opened, it can be seen that HOPG fragments are dispersed. You can see that. Figure 6 (b) is a result of the addition of THF to KI and KOH, it can be seen that the dispersion is better. When K and THF enter together, the interlayer spacing increases, which is more advantageous for dispersing graphite to make graphene. In both cases, it was confirmed that HOPG was completely dispersed by heat and pressure. As a reinforcement experiment, the experiment was conducted without applying pressure (in an unencapsulated container), and no dispersion of HOPG occurred.

Figure 7 is the result of ThermoGravimetric Analysis (TGA) of K-GIC made through KI-KOH conditions.

In the case of pure graphite, the mass change occurs due to oxidation at 800 ℃, but K-GIC is rapidly dropped due to the decrease of van der Waals force with graphite as K intercalated between 400 and 500 ℃ decreases with temperature. A change occurs, and an oxidation temperature is formed below 100 ° C. than pure graphite. From the TGA results, a sudden mass loss occurs at 419.6 ° C., indicating that K-GIC was formed according to this experimental example.

Experimental Example 2

In the second experimental example, a salt mixture of KI and KCl was used as the alkali metal salt to provide K ions.

As shown in FIG. 8, KI and KCl have high eutectic temperatures of 599 ° C., so that only salt cannot disperse graphite below 250 ° C., but the two salts are dissolved in dichlorobenzene (DCB) and then heated to 250 ° C. It was confirmed that the graphite is dispersed.

The specific process is as follows. KI, KCl, DCB and graphite were placed in a container and 250 ° C heat was applied in an encapsulated state to prepare K-GIC. Then, if K-GIC is put in ethanol, the inserted K is released and graphene is made.

When the salt is dissolved in the solvent, it is present as cations and anions, and is electrically neutral. Although the reaction in which the alkali metal is intercalated between the graphite layers is a spontaneous reaction, K ⁺ cannot be intercalated between the graphite layers while breaking the electric neutral state. In the above condition, I ^-of KI and Cl ^- of KCl meet to form a compound called ICl. ICl is a unique compound in which two substances with anionic tendencies meet to form a compound. That is, as ICl is made, K ⁺ becomes K and is intercalated between graphite layers.

ICl is a bronze colored compound. 9 (a) shows a state in which ICl is formed from a bronze color after being subjected to a hot process and dispersed in DCB. However, ICl becomes yellow when it is dissolved in a solvent having an OH- group. FIG. 9 (b) shows a state when mixed with ethanol after DCB dispersion. Therefore, the formation of ICl can be confirmed through the color change of FIGS. 9 (a) and 9 (b).

10 is a Raman spectroscopy (Raman spectroscopy) results of the graphene prepared by the experimental example method. The measurement of Raman spectroscopy Raman shifted (Raman shift) can confirm the 2D peak from the G peak, 2700cm ^-1 in the vicinity of 1350cm ^-1 in the vicinity of the D peak (peak), 1580cm ^-1.

D peak is a peak due to a bond other than sp2 bond of carbon, indicating that other atoms are defective at the edge of graphene, and are a measure of defect. That is, the lower the D peak and the smaller the peak, the better the graphene of high quality. Through the results of Figure 10, it can be seen that the characteristics of the graphene according to the present invention is excellent.

11 is J. Amer. Chem. Soc. 130 (47), 15802 (2008) Raman spectroscopy results from the supplement of the paper. 11, the D peak is very high in this case. In this paper, K-GIC is made using K metal directly.

FIG. 12 also shows Adv. Mater. 21, 1 (2009) Raman spectroscopy results from the paper. Also in FIG. 12, the D peak was formed very high. This paper does not produce GIC by inserting alkali metals, but rather graphene by inserting C ₂ F? NClF ₃ materials between graphite layers.

The comparison between FIG. 10 and FIG. 11 and FIG. 12, which are the result of the present invention, shows that the D peak of the present invention is relatively small and very excellent compared to the G peak.

Figure 13 is a TEM (Transmission Electron Microscopy) photograph of the graphene prepared by the present experimental example, it can be seen that the graphene of a single layer is made. 13 is a high magnification TEM (HRTEM) photograph taken by enlarging a small square portion of the left side. In the case of confirming two or more layers of graphene by HRTEM, the separation of the layer can be confirmed near the boundary. However, in this HRTEM, the interface was identified as a clean one layer. That is, it can be seen that the graphene of a single layer can be produced by dispersing the graphite interlayer compound having K inserted into each layer by the above process method.

14 is an XPS analysis result of graphene prepared in the present experimental example and graphite as a raw material of this process. Referring to FIG. 14, it can be seen that the degree of containing oxygen atoms by the post-process is very small. Therefore, in the above process, in addition to the impurity bond by the raw material graphite, the degree of impurity bonds generated in the process is very small.

Experimental Example 3

In the third experimental example, graphene was prepared by obtaining an alkali metal from an alkali metal salt. K was selected as the alkali metal to be intercalated between the graphite layers, and in order to obtain K, the reaction of the alkali metal salt KI and the solvent DCB was used.

First, Figure 15 is a schematic diagram of a graphene manufacturing method according to the present experimental example.

As shown in Fig. 15, KI, DCB and graphite are placed in a container and heated at 300 ° C in an encapsulated state. Reaction of KI with DCB yields 1-iodine-2-chloro-benzene and K and Cl ₂ . K can be intercalated between graphite layers to produce K-GIC. Then, if K-GIC is put in ethanol, the inserted K is released and K-GIC is dispersed to make graphene.

In fact, gas chromatography / mass spectroscopy was performed to determine whether 1-iodine-2-chloro-benzene was formed through the reaction of KI and DCB. Figure 16 shows that as a result, the result after the reaction is 97% consistent with 1-iodine-2-chloro-benzene.

In addition, the change of pH was confirmed while adding distilled water to confirm whether Cl ₂ is produced through the reaction of KI and DCB. When chlorine gas is produced, the pH is reduced due to HCl by the reaction of Cl ₂ + H ₂ O → HCl + HClO. According to FIG. 17, the pH of the resultant B was 6.38, but the pH was lowered to about 3 when distilled water was added.

16 and 17, it can be verified that 1-iodine-2-chloro-benzene and K and Cl ₂ have been obtained through the reaction of KI and DCB, and as described in the present invention, an alkali metal salt or It can be seen that graphene can be obtained after the preparation of the graphite interlayer compound by obtaining an alkali metal or an alkaline earth metal through the reaction of the alkaline earth metal salt and the solvent.

18 (a) is an HRTEM photograph showing the edge of the graphene prepared by the present experimental example (b) is a HRTEM photograph showing the edge of the multilayer graphene as a comparative example. As shown in FIG. 18 (b), when the graphene is a multilayer, stripes of the number of layers are generated. In the case of Figure 18 (a) it can be seen that there is no stripes appearing in Figure 18 (b), according to this it can be confirmed that the graphene of the monolayer is produced through this experimental example.

FIG. 19 (a) is a reference for informing the diffraction pattern by the (100) plane and the diffraction pattern by the (110) plane, and FIG. 19 (b) is a graph of the graphene manufactured by the present experimental example. Diffraction pattern. In the case of monolayer graphene, it can be seen that the pattern by the inner (100) surface is darker than the pattern of the outer (110) surface. 19 (c) shows a diffraction pattern of multilayer graphene as a comparative example. It can be seen that the pattern on the outer (110) face appears darker. In addition, the hexagonal pattern appears only when the non-oxidized graphene, Figure 19 (b) shows a hexagonal pattern, it can be confirmed that the graphene prepared by the present experimental example is non-oxidized graphene.

The number of layers of graphene can also be confirmed by the 2D peak shape of Raman spectroscopy. Figure 20 (a) is a Raman spectroscopic 2D peak shape of the graphene prepared by the present experimental example, Figure 20 (b) is a 2D peak by attempting Raman mapping analysis of two points of 5um × 3um size By examining the distribution and ratio of the layers according to the shape of, it was confirmed that 11.67% monolayer, 75.83% bilayer graphene is present.

In the Raman spectroscopy of FIG. 21, it can be confirmed whether the graphene manufactured by the present experimental example is of high quality. Graphene using the conventional graphite oxidation-reduction method has a D peak intensity / G peak intensity value of 1.2. However, according to the present experimental example was formed about 0.56. Therefore, it can be seen that the case where the D peak is relatively small compared to the G peak is a method for producing better quality graphene.

22 is an XPS analysis result, it can be seen that a high quality non-oxidized graphene with a very small oxygen content was formed. FIG. 22A shows a wide scan result and FIG. 22B shows a narrow scan near the binding energy of carbon.

23 is an XPS analysis result for confirming whether K, Cl, and I remain in graphene prepared according to the present experimental example. 23 (a), (b), and (c) correspond to binding energies corresponding to K, Cl, and I, respectively. From the analysis results, K, Cl, and I remain in graphene prepared according to the present experimental example. You can see that it is not.

In the above, the present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications are possible by those skilled in the art within the technical idea of the present invention. Is obvious. Embodiments of the invention have been considered in all respects as illustrative and not restrictive, which include the scope of the invention as indicated by the appended claims rather than the detailed description therein, the equivalents of the claims and all modifications within the means. I'm trying to.

Claims (13)

delete Preparing a mixture by mixing a salt mixture obtained by mixing two or more kinds of alkali metal or alkaline earth metal salts in a eutectic molar ratio with graphite;
The mixture is placed in an encapsulated container and heated to above the eutectic point of the salt mixture, so that the alkali metal ions or alkaline earth metal ions produced by melting the salt mixture are intercalated between the layers of graphite to form a layer of the graphite. Increasing the spacing between and separating the graphite layer to form a graphite interlayer compound; And
Obtaining an graphene by removing an alkali metal or alkaline earth metal in atomic form intercalated between the graphite interlayer compounds from the graphite interlayer compound using alcohols having a hydroxyl group (—OH),
At least one of tetrahydrofuran (THF), ammonia, toluene, benzene, dimethyl sulfoxide (DMSO) and dimethylformamide (Dimetylformamide: DMF) may be further used to form the graphite interlayer compound. Graphene manufacturing method. delete delete The method of claim 2, further comprising removing by-products of the forming of the graphite interlayer compound. delete delete The method of claim 2, wherein the alkali metal salt or alkaline earth metal salt is a metal halide. delete Preparing a mixture by mixing a graphite mixture with a salt mixture including two or more alkali metal salts or alkaline earth metal salts;
Placing the mixture in an encapsulated container and heating to dissociate the salt mixture into cations and anions, reacting with each other anions to form byproducts, and inserting the cations between the graphite layers to form graphite intercalation compounds; And
Removing the by-products and using alcohols having a hydroxyl group (-OH) to remove graphene from the graphite interlayer compound in the form of atomic metals or alkaline earth metals intercalated between the graphite interlayers;
At least one of tetrahydrofuran (THF), ammonia, toluene, benzene, dimethyl sulfoxide (DMSO) and dimethylformamide (Dimetylformamide: DMF) may be further used to form the graphite interlayer compound. Graphene manufacturing method. The method of claim 10, wherein the at least two alkali metal salts or alkaline earth metal salts are metal halides. The method of claim 10, wherein the two or more kinds of alkali metal salts or alkaline earth metal salts are mixed in a eutectic molar ratio. delete

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