KR20210128755A - Graphene nanoplate with high specific surface area and method for producing the same - Google Patents

Abstract

The present invention relates to a graphitic nanoplate comprising 95 to 100 parts by weight of carbon and 0 to 2 parts by weight of oxygen, based on 100 parts by weight of the graphitic nanoplate, wherein the specific surface area of the graphitic nanoplate is 2,000 m^2/g or more. The graphitic nanoplate according to the present invention has a low oxygen content, a high specific surface area, and excellent crystallinity, thereby being applied to various uses such as a catalyst support, a chemical catalyst, energy conversion and storage, a fuel cell, and others. In addition, since the graphitic nanoplate is inexpensive and can be produced in large quantities, the cost for processes can be reduced.

Description

A graffiti nanoplate having a high specific surface area and a method for manufacturing the same

The present invention relates to a graphic nanoplate and a method for manufacturing the same. Specifically, it relates to a method for obtaining a graphic nanoplate having a high specific surface area and a low oxygen content and good crystallinity by heat-treating a graphic nanoplate with selectively functionalized edges under a carbon dioxide atmosphere.

Graphene is a basic unit of graphite and is a thin film made of a thickness of one carbon atom. Specifically, it is a two-dimensional planar material in which carbon forms a covalent bond in a hexagonal shape. Graphene is a material with excellent physical and chemical properties with thermal and electrical conductivity. Methods for producing such graphene include mechanical exfoliation, chemical exfoliation, exfoliation-reinsertion-expansion, chemical vapor deposition, epitaxy synthesis, and chemical synthesis.

The mechanical exfoliation method preserves the excellent properties of graphene as it is, but the final yield is extremely low, so it is only used for research on the properties of graphene in laboratories and the like.

Graphene prepared by chemical vapor deposition is reported to show excellent properties, but it requires a heavy metal catalyst, can be synthesized at a high temperature (about 1,000 ° C), and has limited production capacity depending on the area of the substrate used.

The epitaxial synthesis method has a disadvantage in that the electrical properties of the produced graphene are poor and the substrate is very expensive.

Overcoming the shortcomings of the conventional method of manufacturing graphene, a method of manufacturing graphite selectively functionalized only at the edges mechanically and chemically using a ball mill process is attracting attention as a method for manufacturing graphene in large quantities at low cost.

High specific surface area, low oxygen content, and excellent crystallinity are required in order to use graphite with functionalized edges by mechanochemical methods as capacitors and catalyst supports. An activation process and an additional reduction process are required to achieve this. Conventionally, there is a problem in that the activation process is performed using a chemical agent or high-temperature steam, thereby exposing to a risk in the process process.

Korean Patent Publication No. 10-2017-0136147

The present application relates to a graphic nanoplate and a method for manufacturing the same for solving the problems of the prior art, and a high specific surface area, low oxygen content, and excellent crystallinity can be achieved only by a simple process of heat treatment in a carbon dioxide atmosphere.

The graffiti nanoplate of the present invention for achieving the above technical problem, based on 100 parts by weight of the graffiti nanoplate, 95 parts by weight to 100 parts by weight of carbon; and 0 parts by weight to 2 parts by weight of oxygen, wherein the specific surface area of the graffiti nanoplate is 2,000 m ² /g or more.

The size of the [002] peak in the XRD analysis of the graphic nanoplate may be 2 to 20 times larger than the [100] peak, but is not limited thereto.

Based on 100 parts by weight of the graffiti nanoplate, the oxygen may include 0.1 parts by weight to 0.5 parts by weight, but is not limited thereto.

The specific surface area of the graffiti nanoplate may be 2,000 m ² /g to 2,800 m ² /g, but is not limited thereto.

A method for manufacturing a graffiti nanoplate includes the steps of mechanically pulverizing graphite under an inert gas atmosphere; and heat-treating the pulverized graphite under a carbon dioxide atmosphere.

The carbon dioxide may be injected at 100 ml to 1,000 ml per minute, but is not limited thereto.

The heat treatment may be performed at a temperature of 700°C to 1,200°C, but is not limited thereto.

The heat treatment may be performed for 5 to 7 hours, but is not limited thereto.

The above-described problem solving means are merely exemplary, and should not be construed as limiting the present application. In addition to the exemplary embodiments described above, additional embodiments may exist in the drawings and detailed description.

The disclosed technology may have the following effects. However, this does not mean that a specific embodiment should include all of the following effects or only the following effects, so the scope of the disclosed technology should not be construed as being limited thereby.

According to the above-described means for solving the problems of the present application, the graphic nanoplate according to the present application has a low oxygen content, a high specific surface area, and excellent crystallinity. Conventionally, there is a problem of being exposed to risks in the process by using chemicals and/or high-temperature steam as an activation process and/or a reduction process to achieve these conditions. The graffiti nanoplate according to the present application was effectively activated by heat treatment in a carbon dioxide atmosphere. The present application has the advantage of being able to simply and safely obtain activated graffiti nanoplates using only carbon dioxide.

The graffiti nanoplate according to the present application can be applied to various uses such as catalyst support, chemical catalyst, energy conversion and storage, and fuel cell. In addition, since it is inexpensive and can be manufactured in large quantities, it is easy to reduce the cost of the process.

1 is a flowchart of a method of manufacturing a graffiti nanoplate according to an embodiment of the present application.
2 is an X-ray diffraction (XRD) graph of a graffiti nanoplate according to an embodiment and a comparative example of the present application.
3 is a graph showing the specific surface area according to the carbon dioxide injection amount of the graffiti nanoplate according to an embodiment and a comparative example of the present application.
4 is a graph showing the specific surface area according to the heat treatment temperature of the graffiti nanoplate according to an embodiment and a comparative example of the present application.
5 is a graph showing the specific surface area according to the heat treatment time of the graffiti nanoplate according to an embodiment and a comparative example of the present application.
6 is a graph showing the specific surface area according to the injected gas of the graffiti nanoplate according to an embodiment and a comparative example of the present application.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. However, this is not intended to limit the present invention to a specific embodiment, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

In describing each figure, like reference numerals are used for like components. The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The term “and/or” includes a combination of a plurality of related listed items or any of a plurality of related listed items.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. shouldn't

Throughout this specification, when it is said that a member is positioned "on", "on", "on", "under", "under", or "under" another member, this means that a member is positioned on the other member. It includes not only the case where they are in contact, but also the case where another member exists between two members.

Throughout this specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

As used herein, the terms "about," "substantially," and the like are used in a sense at or close to the numerical value when the manufacturing and material tolerances inherent in the stated meaning are presented, and to aid in the understanding of the present application. It is used to prevent an unconscionable infringer from using the mentioned disclosure in an unreasonable manner. Also, throughout this specification, "step to" or "step to" does not mean "step for".

Throughout this specification, the term "combination of these" included in the expression of the Markush form means one or more mixtures or combinations selected from the group consisting of the components described in the expression of the Markush form, and the components It is meant to include one or more selected from the group consisting of.

Hereinafter, the graphic nanoplate of the present application and a method for manufacturing the same will be described in detail with reference to embodiments, examples, and drawings. However, the present application is not limited to these embodiments and examples and drawings.

Herein, based on 100 parts by weight of the graffiti nanoplate, 95 parts by weight to 100 parts by weight of carbon; and 0 parts by weight to 2 parts by weight of oxygen, wherein the specific surface area of the graffiti nanoplate is 2,000 m ² /g or more.

The size of the [002] peak in the XRD analysis of the graphic nanoplate may be 2 to 20 times larger than the [100] peak, but is not limited thereto.

In XRD (X-ray diffraction) analysis, the [002] peak may appear at around 26.5°, and the [100] peak may appear at around 43.5°.

In general, graphite has a narrow and large peak in XRD analysis. On the other hand, when impurities such as graphene oxide, redox graphene, etc. are included, the peak appears wide and small in XRD analysis. That is, as the [002] peak appears narrower and larger, it is similar to the crystallinity of graphite, and it can be determined that the crystallinity is good.

In the graphitic nanoplate according to the present application, in XRD analysis, the size of the [002] peak is 2 to 20 times larger than that of the [100] peak, and through this, it can be determined that the crystallinity is good.

Based on 100 parts by weight of the graffiti nanoplate, the oxygen may include 0.1 parts by weight to 0.5 parts by weight, but is not limited thereto.

The graphic nanoplate according to the present application is activated by heat-treating graphene with selectively functionalized edges under a carbon dioxide atmosphere. On the other hand, in the case of graphene oxide or reduced graphene oxide, since functionalization is made randomly, the specific surface area may increase even after activation, but has a disadvantage in that the oxygen content is high and crystallinity is low. The present application can obtain a graphic nanoplate having a high specific surface area as well as a low oxygen content and high crystallinity by solving this problem. Moreover, when the graphene oxide is heat-treated in a carbon dioxide atmosphere, the graphene oxide is completely burned out, so that meaningful graphene cannot be obtained. This is because, in the case of graphene oxide, thermal stability is poor due to a large amount of oxygen functional groups. Therefore, in order to heat-treat graphene oxide, the heat treatment should be performed in an inert gas atmosphere. However, when the heat treatment is performed in an inert gas atmosphere, activation does not occur sufficiently.

The graffiti nanoplate according to the present application contains 0 parts by weight to 2 parts by weight, more preferably 0.1 parts by weight 0.5 parts by weight, and 95 parts by weight to 100 parts by weight of carbon relative to 100 parts by weight of the graffiti nanoplate. contains That is, since the graffiti nanoplate of the present application contains a high carbon ratio to oxygen content, it can be expected to have high electrical conductivity.

The specific surface area of the graffiti nanoplate may be 2,000 m ² /g to 2,800 m ² /g, but is not limited thereto.

The graffiti nanoplate according to the present application has a low oxygen content, a high specific surface area, and excellent crystallinity. Conventionally, there is a problem of being exposed to risks in the process by using chemicals and/or high-temperature steam as an activation process and/or a reduction process to achieve these conditions. The graffiti nanoplate according to the present application was effectively activated by heat treatment in a carbon dioxide atmosphere. The present application has the advantage of being able to simply and safely obtain activated graffiti nanoplates using only carbon dioxide.

The average diameter of the graffiti nanoplate may be 50 nm or more, but is not limited thereto.

The graffiti nanoplate according to the present application can be applied to various uses such as catalyst support, chemical catalyst, energy conversion and storage, and fuel cell. In addition, since it is inexpensive and can be manufactured in large quantities, it is easy to reduce the cost of the process.

Moreover, by blocking the introduction of impurities such as oxygen, it is possible to suppress the change in physical properties of the graffiti nanoplate due to the introduction of the impurities.

The present application includes the steps of mechanically pulverizing graphite under a reaction gas atmosphere; and heat-treating the pulverized graphite under a carbon dioxide atmosphere.

1 is a flowchart of a method of manufacturing a graffiti nanoplate according to an embodiment of the present application.

First, graphite is mechanically pulverized under a reaction gas atmosphere (S100).

The reaction gas may include carbon dioxide and/or an inert gas, but is not limited thereto.

The weight ratio of the graphite and the inert gas may be 1:3 to 1:5, but is not limited thereto.

The molar ratio of the graphite and the inert gas may be 1:3 to 1:5, but is not limited thereto.

The inert gas may include a gas selected from the group consisting of helium, argon, neon, nitrogen, and combinations thereof, but is not limited thereto.

The reaction vessel for pulverizing the graphite may be made of any material, but it is preferable to use a reaction vessel made of a metal material.

The pulverization may be pulverizing at a speed of 300 rpm to 600 rpm for 24 hours to 60 hours, but is not limited thereto.

In the pulverization step, a carbon source may be additionally injected, but the present invention is not limited thereto.

The carbon source may include a carbon-containing compound having 1 to 7 carbon atoms, but is not limited thereto.

The carbon source is selected from the group consisting of methane, ethane, ethylene, carbon monoxide, ethanol, acetylene, propane, propylene, butane, butadiene, pentane, fenrene, cyclopentadiene, hexane, cyclohexane, benzene, toluene, and combinations thereof. It may include a material, but is not limited thereto.

As the graphite is pulverized through the pulverization process, carbon at the edge of the graphite is charged or is in the form of a radical. The charged or radically formed carbon reacts with the reactive gas to form graphene with selectively functionalized edges.

By mechanically pulverizing the graphite under a reaction gas atmosphere, graphene with selectively functionalized edges can be obtained.

Then, the pulverized graphite is heat-treated under a carbon dioxide atmosphere (S200).

The carbon dioxide may be injected at 100 ml to 1,000 ml per minute, but is not limited thereto.

When the carbon dioxide is injected at less than 100 ml per minute or more than 1,000 ml per minute, the specific surface area of the graffiti nanoplate may not be sufficiently increased.

The heat treatment may be performed at a temperature of 700°C to 1,200°C, but is not limited thereto.

When the heat treatment temperature is less than 700° C. or higher than 1,200° C., the specific surface area of the graffiti nanoplate may not be sufficiently increased.

The heat treatment may be performed for 5 to 7 hours, but is not limited thereto.

When the heat treatment time is less than 5 hours and more than 7 hours, the specific surface area of the graffiti nanoplate may not be sufficiently increased.

With respect to the manufacturing method of the graffiti nanoplate of the present application, a detailed description of parts overlapping with the graffiti nanoplate of the present application is omitted. The same can be applied to the manufacturing method of the nanoplate.

The present invention will be described in more detail through the following examples, but the following examples are for illustrative purposes only and are not intended to limit the scope of the present application.

First, 80 g of graphite (99%, 32 mesh) was placed in a 500 ml metal grinding container. The air in the metal grinding vessel was removed using a vacuum pump, carbon dioxide 1 MPa was injected, and then the metal grinding vessel was pulverized at a speed of about 350 rpm for 48 hours. After the grinding was finished, the grinding material was treated with 1 M hydrochloric acid for 48 hours to completely remove the graphite and unreacted metals. After placing the pulverized graphite in an electric furnace, 300 ml of carbon dioxide was injected per minute and heat treatment was performed at a temperature of 900° C. for 6 hours to prepare a graffiti nanoplate.

A graffiti nanoplate was prepared in the same manner as in Example 1, except that 100 ml of carbon dioxide was injected per minute into the electric furnace.

A graphic nanoplate was prepared in the same manner as in Example 1, except that 500 ml of carbon dioxide was injected per minute into the electric furnace.

A graphic nanoplate was prepared in the same manner as in Example 1, except that the heat treatment was performed under a temperature of 700°C.

A graphic nanoplate was prepared in the same manner as in Example 1, except that the heat treatment was performed at a temperature of 800°C.

[Comparative Example 1]

First, 80 g of graphite (99%, 32 mesh) was placed in a 500 ml metal grinding container. The air in the metal grinding vessel was removed using a vacuum pump, carbon dioxide 1 MPa was injected, and then the metal grinding vessel was pulverized at a speed of about 350 rpm for 48 hours. After all grinding was completed, the grinding material was treated with 1 M hydrochloric acid for 48 hours to completely remove the graphite and unreacted metals to obtain non-activated graphic nanoplates.

[Comparative Example 2]

A graphic nanoplate was prepared in the same manner as in Example 1, except that the heat treatment was performed for 2 hours.

[Comparative Example 3]

A graphic nanoplate was prepared in the same manner as in Example 1, except that the heat treatment was performed for 4 hours.

[Comparative Example 4]

A graphic nanoplate was prepared in the same manner as in Example 1, except that the heat treatment was performed for 8 hours.

[Comparative Example 5]

A graphic nanoplate was prepared in the same manner as in Example 1, except that nitrogen instead of carbon dioxide was injected into the electric furnace.

[Comparative Example 6]

A graphic nanoplate was prepared in the same manner as in Example 1, except that carbon dioxide and hydrogen were injected into the electric furnace instead of carbon dioxide.

[Comparative Example 7]

A graphic nanoplate was prepared in the same manner as in Example 1, except that water vapor instead of carbon dioxide was injected into the electric furnace.

[Comparative Example 8]

The heat-treated graphene oxide (H-GO) was obtained by heat-treating graphene oxide at a temperature of 900° C. for 6 hours.

[evaluation]

1. Characterization of graffiti nanoplates

Elemental analysis of the graphic nanoplates prepared in Examples and Comparative Examples was performed, and the results are shown in Table 1 below.

Sample carbon content
(wt%) hydrogen content
(wt%) Oxygen content (wt%) Other (wt%) Example 1 97.94 0.20 0.49 - Comparative Example 1 85.04 1.10 11.00 - Comparative Example 8 91.98 0.26 1.60 Nitrogen: 0.15
Sulfur: 0.49

According to the results shown in Table 1, it can be confirmed that the oxygen content of the graphic nanoplate prepared in Example 1 was the least detected as 0.49%. On the other hand, in Comparative Example 1, which is a non-activated graphic nanoplate, it can be confirmed that a large amount of oxygen was detected with an oxygen content of 11.00%. In addition, the heat-treated graphene oxide Comparative Example 8 had an oxygen content of 1.60%, which was significantly lower than that of Comparative Example 1, but impurities such as nitrogen and sulfur were simultaneously detected, and the carbon content was 91.98% in Example 1 It can be seen that it is much lower than the carbon content of 97.94% of the graphic nanoplate. As a result, the carbon/oxygen (C/O) ratio of the graffiti nanoplate of the present application is higher than that of the heat-treated graphene oxide, so it can be expected that properties such as electrical conductivity are better.

In order to confirm the crystallinity of the graphic nanoplates prepared in Example 1, Comparative Example 1 and Comparative Example 8, XRD analysis was performed, and the results are shown in FIG. 2 .

2 is an X-ray diffraction (XRD) graph of a graffiti nanoplate according to an embodiment and a comparative example of the present application.

According to the results shown in FIG. 2, it can be confirmed that the [002] peak of Example 1 is narrow and the magnitude of the intensity is the highest. In particular, the [002] peak indicates a higher peak size than the [100] peak. On the other hand, in the case of Comparative Example 1, which is not activated, it can be seen that the sizes of the [002] peak and the [100] peak are similar. In addition, in the case of Comparative Example 8, the [002] peak appears to be larger than the [100] peak, but the [002] peak is wide and the magnitude of the intensity is low. That is, it can be seen that the crystallinity of the graphic nanoplate prepared in Example 1 is higher than that of Comparative Example 8.

2. Analysis of specific surface area of graffiti nanoplates according to experimental conditions

Specific surface area analysis of the graffiti nanoplates prepared in Examples and Comparative Examples was performed, and the results are shown in FIGS. 3 to 6 below.

(One) Graphical nanoplate according to the amount of carbon dioxide injected

In order to analyze the specific surface area of the graffiti nanoplate according to the amount of carbon dioxide injected, the graph of the specific surface area analysis of the graffiti nanoplates prepared in Examples 1 to 3 and Comparative Example 1 is shown in FIG. 3 .

3 is a graph showing the specific surface area according to the carbon dioxide injection amount of the graffiti nanoplate according to an embodiment and a comparative example of the present application.

According to the results shown in FIG. 3 , the specific surface area of Comparative Example 1, which is a non-activated graphic nanoplate, exhibited a very low specific surface area of about ^{500 m 2 /g.} On the other hand, the specific surface areas of the graphic nanoplates (Examples 1 to 3) activated by heat treatment in a carbon dioxide atmosphere were all 1,500 m ² /g or more, indicating a high specific surface area. In particular, it can be seen that the specific surface area of the graffiti nanoplate prepared in Example 1 in which the injection amount of carbon dioxide is 300 ml per minute is about 2,500 m ² /g, which is the highest.

(2) Graffiti nanoplate according to heat treatment temperature

In order to analyze the specific surface area of the graffiti nanoplate according to the heat treatment temperature, graphs of the specific surface area analysis of the graffiti nanoplates prepared in Examples 1, 4, 5 and Comparative Example 1 are shown in FIG. 4 .

4 is a graph showing the specific surface area according to the heat treatment temperature of the graffiti nanoplate according to an embodiment and a comparative example of the present application.

According to the results shown in FIG. 4 , the specific surface area of Comparative Example 1, which is a non-activated graphic nanoplate, exhibited a very low specific surface area of about ^{500 m 2 /g.} On the other hand, the specific surface areas of the graffiti nanoplates (Examples 1, 4, and 5) activated by heat treatment in a carbon dioxide atmosphere all showed a high specific surface ^{area of 2,500 m 2 /g or more.}

(3) Graffiti nanoplate according to heat treatment time

In order to analyze the specific surface area of the graffiti nanoplate according to the heat treatment time, a graph of the specific surface area analysis of the graffiti nanoplates prepared in Example 1 and Comparative Examples 1 to 4 is shown in FIG. 5 .

5 is a graph showing the specific surface area according to the heat treatment time of the graffiti nanoplate according to an embodiment and a comparative example of the present application.

According to the results shown in FIG. 5 , the specific surface area of Comparative Example 1, which is a non-activated graphic nanoplate, exhibited a very low specific surface area of about ^{500 m 2 /g.} In addition, although the specific surface area of the graffiti nanoplates of Comparative Examples 2 to 4 in which the heat treatment time was 2 hours, 4 hours, and 8 hours was significantly increased compared to before activation, it was confirmed that it was less than ^{1,500 m 2 /g.} On the other hand, the specific surface area of the graffiti nanoplate of Example 1, which was heat treated for 6 hours, was 2,500 m ² /g or more, indicating a high specific surface area.

(4) Graffiti nanoplate according to the injected gas

In order to analyze the specific surface area of the graffiti nanoplate according to the injected gas, the graph of the specific surface area analysis of the graffiti nanoplates prepared in Example 1 and Comparative Examples 1, 5, 6 and 7 is shown in FIG. 6 .

6 is a graph showing the specific surface area according to the injected gas of the graffiti nanoplate according to an embodiment and a comparative example of the present application.

According to the results shown in FIG. 6 , the specific surface areas of Comparative Examples 1 and 5, which are non-activated or nitrogen-injected graphic nanoplates, exhibit a very low specific surface area of about ^{500 m 2 /g.} In addition, although the specific surface area of the graphic nanoplates of Comparative Example 6 in which carbon dioxide and hydrogen were simultaneously injected and Comparative Example 7 in which water vapor was injected was increased compared to before activation, it can be confirmed that it was less than ^{1,500 m 2 /g.} On the other hand, the specific surface area of the graffiti nanoplate of Example 1, which was heat-treated in a carbon dioxide atmosphere, was 2,500 m ² /g or more, indicating a high specific surface area.

The above description of the present application is for illustration, and those of ordinary skill in the art to which the present application pertains will understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present application. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present application.

Claims (8)

In the graphic nanoplate,
Based on 100 parts by weight of the graphic nanoplate,
95 parts by weight to 100 parts by weight of carbon; and
Oxygen 0 parts by weight to 2 parts by weight; contains,
The specific surface area of the graffiti nanoplate is 2,000 m ² /g or more, the graffiti nanoplate.
The method of claim 1,
In the XRD analysis of the graphic nanoplate, the size of the [002] peak is 2 to 20 times larger than that of the [100] peak, the graphic nanoplate.
The method of claim 1,
Based on 100 parts by weight of the graffiti nanoplate, the oxygen comprises 0.1 parts by weight to 0.5 parts by weight, the graffiti nanoplate.
The method of claim 1,
The specific surface area of the graffiti nanoplate is 2,000 m ² /g to 2,800 m ² /g, the graffiti nanoplate.
mechanically pulverizing graphite under a reaction gas atmosphere; and
Heat-treating the pulverized graphite under a carbon dioxide atmosphere; including, a method of manufacturing a graffiti nanoplate.
6. The method of claim 5,
The carbon dioxide is to inject 100 ml to 1,000 ml per minute, the method for producing a graffiti nanoplate.
6. The method of claim 5,
The heat treatment is made under a temperature of 700 ℃ to 1,200 ℃, the method of manufacturing a graffiti nanoplate.
6. The method of claim 5,
The heat treatment is to be performed for 5 to 7 hours, the method of manufacturing a graffiti nanoplate.

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