KR102289201B1 - Graphene synthesis apparatus and graphene synthesis method by electrochemical treatment - Google Patents

Abstract

The present invention provides a graphene synthesis apparatus and a graphene synthesis method, wherein the graphene synthesis apparatus comprises: a reaction chamber defining a space where graphene is synthesized; a first counter electrode disposed inside the reaction chamber; a second counter electrode disposed to face the first counter electrode inside the reaction chamber; and N working electrodes (where N is an integer greater than or equal to 2) disposed with a predetermined interval between the first counter electrode and the second counter electrode, wherein each N working electrode is independently and electrochemically connected to the first counter electrode and the second counter electrode, and graphene is synthesized on the working electrode.

Description

Graphene synthesis apparatus and graphene synthesis method by electrochemical treatment {Graphene synthesis apparatus and graphene synthesis method by electrochemical treatment}

The present invention relates to an apparatus for synthesizing graphene by electrochemical treatment and a method for synthesizing graphene, and more particularly, to an apparatus and method for synthesizing graphene by electrochemical treatment using a plurality of working electrodes.

Graphene is a two-dimensional sheet composed of sp ^{2 carbon having a honeycomb structure and having an atomic thickness.} Since graphene was first isolated by Professor Geim's group in 2004, research in related fields has rapidly increased. However, a significant portion of these graphene manufacturing-related technologies are not for the actual single-layer graphene, but for several-layer graphene having a thickness of 2 to 10 graphene layers, or a large amount in the exfoliation process used to make graphene. Most of it is about graphene oxide (GO) oxidized with

In order to solve the problems in the production of these nanometer-sized carbon materials, exfoliated graphite of micrometer scale having properties similar to graphene by directly exfoliating low-cost natural graphite through physical and chemical methods. Research on manufacturing has been actively carried out.

Recently, Professor Mullen's research team at the Max Planck Institute in Germany produced high-quality exfoliated graphite in a short time in a short time without using special physical pressure or toxic strong acids such as sulfuric acid and nitric acid through a simple electrochemical process. A manufacturing process that can be produced has been developed (Mullen et al., J. Am. Chem. Sos. 2014, 135, 6083.). As a related patent technology, Korean Patent Application Laid-Open No. 2013-0087018 discloses a technique for exfoliating graphite using an organic solvent such as propylene carbonate and dimethylformamide, lithium salt, and ultrasonic waves, and Korean Patent Application Laid-Open No. 2016-0079115 discloses a technology using sodium citrate as an electrolyte as a technology capable of producing graphene oxide in a suitable yield and thickness while maintaining a desired level of oxidation by an exfoliation method through an electrochemical reaction.

However, the platinum (Pt) electrode, which is generally used in most electrochemical reactions up to now, is very expensive, although it has excellent electrical activity and strong corrosion resistance. In particular, in producing high-quality exfoliated graphite, it is necessary to produce a large amount in a short time in order to increase economic feasibility. The difficulty is a major obstacle to mass production and commercialization through the process.

An object of the present invention is to provide an apparatus and method capable of rapidly producing a large amount of graphene at a relatively low cost.

One aspect of the present invention is a reaction chamber defining a space in which graphene is synthesized;

a first counter electrode disposed inside the reaction chamber;

a second counter electrode disposed inside the reaction chamber to face the first counter electrode; and

including N working electrodes (wherein N is an integer of 2 or more) disposed with a predetermined interval between the first counter electrode and the second counter electrode;

The N working electrodes are each independently electrochemically connected to the first counter electrode and the second counter electrode, and graphene is synthesized on the working electrode to provide a graphene synthesizing apparatus.

In one specific example, the first counter electrode may be each electrochemically connected to the N working electrodes, and the second counter electrode may be each electrochemically connected to the N working electrodes.

In one specific example, the first counter electrode and the second counter electrode may each independently be a metal electrode or a graphite electrode.

In one specific example, the N working electrodes may be graphite electrodes.

In one specific example, the first counter electrode, the second counter electrode, and the N working electrodes may each independently be in the form of a sheet, a foil, or a plate.

In one specific example, an electrolyte may be further included in the reaction chamber.

For example, the electrolyte may include an anionic electrolyte, a cationic electrolyte, ionic liquids, or a combination thereof.

For example, the anionic electrolyte may include sulfate (SO ₄ ^2- ), nitrate (NO ₃ ^- ), phosphate (PO ₄ ^3- ), or a combination thereof.

For example, the cationic electrolyte may be a metal halide. For example, the metal halide ^{may be a halogen salt including Li +} , Na ⁺ , K ⁺ , and the like, for example, the metal halide may be LiCl.

For example, the ionic liquid may include an anionic ionic liquid, a cationic ionic liquid, or a combination thereof. For example, the cationic ionic liquid may include an ammonium-based ionic liquid, an imidazolium-based ionic liquid, a pyrrolidinium-based ionic liquid, or a combination thereof.

Another aspect of the present invention comprises the steps of introducing an electrolyte into the reaction chamber;

disposing a first counter electrode and a second counter electrode to face each other in the electrolyte;

disposing N working electrodes (wherein N is an integer of 2 or more) with a predetermined interval between the first counter electrode and the second counter electrode;

electrochemically connecting the N working electrodes independently of each other to a first counter electrode and a second counter electrode, respectively; and

Applying a voltage to the first counter electrode, the second counter electrode, and the N number of working electrodes to synthesize graphene on the working electrode; provides a graphene synthesis method comprising a.

In one specific example, by applying the voltage, a direct current of 0.1 to 5A may flow.

Since the graphene synthesis apparatus of the present invention includes two counter electrodes, the synthesis reaction of graphene occurs on both surfaces of the working electrode where graphene is synthesized, and thus the production rate and production can be increased.

In addition, by increasing the number of working electrodes included in the device of the same size as compared to the prior art, the process space required for synthesizing the same amount of graphene can be reduced, and the production rate and production speed can also be increased.

1 is a schematic diagram showing the structure of a graphene synthesis apparatus according to an embodiment of the present invention.
2 is a schematic diagram showing the structure of a graphene synthesis device incorporating a conventional multi-electrode system.
3A to 3D are photographs showing a graphene synthesis apparatus and a graphene synthesis process according to an embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed subject matter may be thorough and complete, and that the spirit of the present invention may be sufficiently conveyed to those skilled in the art.

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

In general, the amount of graphene (exfoliated graphite) produced through an electrochemical exfoliation process of a pair of a metal electrode (counter electrode) and a graphite electrode (working electrode) is inevitably limited, and the amount of graphene produced in several batches is limited. Since it is difficult to uniformly control the quality, manufacturing a large amount of graphene in one electrochemical batch is a very important factor in a low-cost mass production process. Therefore, in order to increase the single batch production of graphene, it is necessary to first enlarge the area of the metal electrode and the graphite electrode. However, if the size of the graphite electrode increases, the time of the exfoliation process becomes longer, and electrochemical reaction for a long time may cause electrooxidation. As this size increases, the fairness and the quality of the produced graphene deteriorate.

As a method to solve this problem, a multi-electrode system in which the number of graphite electrodes and metal electrodes is increased has been proposed.

2 is a schematic diagram showing the structure of a graphene synthesis device incorporating a conventional multi-electrode system.

Referring to FIG. 2 , the conventional graphene synthesizing apparatus 20 has graphite electrodes 221 , 222 , 223 as working electrodes therebetween, and metal electrodes 211 , 212 , 213 and 214 as counter electrodes on both sides. After disposing the electrolyte 230, electricity is applied to generate a peeling phenomenon on both surfaces of the graphite electrodes 221, 222, and 223.

That is, the conventional graphene synthesis apparatus 20 includes N+1 metal electrodes 211, 212, 213, and 214 with N graphite electrodes 221, 222, 223 interposed therebetween, and the graphite electrode ( 221, 222, and 223), by producing graphene on both sides, it was possible to increase the production compared to the conventional time.

Nevertheless, there is still a need for synthesizing a larger amount of graphene at a faster rate.

1 is a schematic diagram showing the structure of a graphene synthesis apparatus according to an embodiment of the present invention.

Referring to FIG. 1 , the graphene synthesis apparatus 10 includes a reaction chamber 100 defining a space in which graphene is synthesized; a first counter electrode 111 disposed inside the reaction chamber 100; a second counter electrode 112 disposed in the reaction chamber 100 to face the first counter electrode 111; and N working electrodes 121 , 122 , 123 , 124 and 125 disposed with a predetermined interval between the first counter electrode 111 and the second counter electrode 112 , where N is an integer greater than or equal to 2 . ), wherein the N working electrodes 121, 122, 123, 124, and 125 are each independently electrochemically connected to the first counter electrode 111 and the second counter electrode 112, and the Graphene is synthesized on the working electrodes 121 , 122 , 123 , 124 , and 125 .

In FIG. 1 , the case where N is 5 is shown, but the present invention is not limited thereto, and the case where N is an integer of 5 or more may also be applied.

That is, the graphene synthesizing apparatus 10 shown in FIG. 1 is compared to the conventional graphene synthesizing apparatus 20 shown in FIG. 2 , even if the number of working electrodes is increased, the number of counter electrodes is reduced to two without a change in the number of counter electrodes. While maintaining, the first counter electrode 111 of the N working electrodes 121 , 122 , 123 , 124 , 125 disposed between the first counter electrode 111 and the second counter electrode 112 disposed on both sides, and Through an electrochemical connection to the second counter electrode 112 , graphene may be synthesized on both surfaces of the N working electrodes 121 , 122 , 123 , 124 , and 125 when a voltage is applied.

Therefore, by increasing the number of working electrodes included in the device of the same size compared to the prior art, the process space required to synthesize the same amount of graphene can be reduced, and the production volume and production speed can also be increased.

For example, the first counter electrode 111 is electrochemically connected to each of the N working electrodes 121, 122, 123, 124, and 125, and the second counter electrode 112 is connected to the N working electrodes ( 121, 122, 123, 124, and 125) may be electrochemically connected to each other.

In the present specification, "electrochemically connected" may mean, for example, electrical connection. For example, the first counter electrode and the second counter electrode may be negative electrodes, and the N working electrodes may be positive electrodes. For example, the first counter electrode and the second counter electrode may be positive electrodes, and the N working electrodes may be negative electrodes.

For example, as shown in FIG. 1 , terminals for electrical connection may be disposed on the first counter electrode 111 and the second counter electrode 112 .

3A to 3D are photographs showing a graphene synthesis apparatus and a graphene synthesis process according to an embodiment of the present invention.

Specifically, Figure 3a is a step before the graphene synthesis reaction, an electrolyte is introduced into a reaction chamber, a first counter electrode and a second counter electrode are arranged to face each other in the electrolyte, and the first counter electrode and the second counter electrode The N working electrodes are disposed with a predetermined interval between the electrodes, and the N working electrodes are each independently electrochemically connected to the first counter electrode and the second counter electrode. Subsequently, a reaction of synthesizing graphene on the working electrode by applying a voltage to the first counter electrode, the second counter electrode, and the N working electrodes proceeds. FIGS. 3B and 3C are a stage during the reaction, and FIG. 3D is the end stage of the graphene synthesis reaction, and FIGS. 3A to 3D show the reaction sequence.

Referring to FIGS. 3A to 3D together with FIG. 1 , the first counter electrode 111 is electrochemically connected to the N working electrodes 121, 122, 123, 124, and 125, respectively, and the second counter electrode ( 112 ) may be specifically confirmed to be electrochemically connected to each of the N working electrodes 121 , 122 , 123 , 124 , and 125 .

For example, the first counter electrode 111 and the second counter electrode 112 may each independently be a metal electrode or a graphite electrode.

For example, the metal electrode may include stainless steel, nickel, or a combination thereof.

For example, the graphite electrode may be independently of each other, hard carbon, soft carbon, artificial graphite, natural graphite, graphitized carbon fiber, graphitized mesocarbon microbead, petroleum coke, plastic resin, carbon fiber, pyrolytic carbon, or combinations thereof may be included.

For example, the first counter electrode 111 and the second counter electrode 112 may be metal electrodes.

For example, the first counter electrode 111 and the second counter electrode 112 may be the same as or different from each other.

For example, the N working electrodes 121 , 122 , 123 , 124 , and 125 may be graphite electrodes.

For example, the N working electrodes 121 , 122 , 123 , 124 , and 125 are independent of each other, hard carbon, soft carbon, artificial graphite, natural graphite, graphitized carbon fiber, graphitized mesocarbon microbead, petroleum It may include coke, plastic resin, carbon fiber, pyrolytic carbon, or a combination thereof.

For example, the N working electrodes 121 , 122 , 123 , 124 , and 125 may be the same as or different from each other.

As described above, since it is necessary to enlarge the areas of the metal electrode and the graphite electrode in order to increase the production amount of graphene in a single batch, the first counter electrode 111 , the second counter electrode 112 , and the N working electrodes (121, 122, 123, 124, 125) may be in the form of a sheet, foil, or plate.

The graphene synthesis apparatus 10 may further include an electrolyte 130 in the reaction chamber 100 .

The electrolyte 130 is not particularly limited, but may include, for example, an anionic electrolyte, a cationic electrolyte, an ionic liquid, or a combination thereof.

For example, the anionic electrolyte may include sulfate (SO ₄ ^2- ), nitrate (NO ₃ ^- ), phosphate (PO ₄ ^3- ), or a combination thereof.

For example, the sulfate may be one or more selected from _{ammonium sulfate ((NH 4} ) ₂ SO ₄ ), potassium sulfate (K ₂ SO ₄ ), and sodium sulfate (Na ₂ SO _{4 ).}

For example, the nitrate may be at least one selected from _{ammonium nitrate ((NH 4} )NO ₃ ), potassium nitrate (KNO ₃ ), and sodium nitrate (NaNO _{3 ).}

For example, the phosphate salt may be at least one selected from _{ammonium phosphate ((NH 4} ) ₃ PO ₄ ), potassium phosphate (K ₃ PO ₄ ), and sodium phosphate (Na ₃ PO _{4 ).}

For example, the cationic electrolyte may be a metal halide. For example, the metal halide ^{may be a halogen salt including Li +} , Na ⁺ , K ⁺ , and the like, for example, the metal halide may be LiCl.

For example, the ionic liquid may include an anionic ionic liquid, a cationic ionic liquid, or a combination thereof. For example, the cationic ionic liquid may include an ammonium-based ionic liquid, an imidazolium-based ionic liquid, a pyrrolidinium-based ionic liquid, or a combination thereof.

Another aspect of the present invention includes the steps of introducing the electrolyte 130 into the reaction chamber 100; disposing a first counter electrode 111 and a second counter electrode 112 in the electrolyte 130 to face each other; N number of working electrodes 121 , 122 , 123 , 124 , and 125 are disposed between the first counter electrode 111 and the second counter electrode 112 with a predetermined interval, where N is an integer greater than or equal to 2 . to do; electrochemically connecting the N working electrodes (121, 122, 123, 124, 125) to the first counter electrode (111) and the second counter electrode (112) independently of each other, respectively; and applying a voltage to the first counter electrode 111 , the second counter electrode 112 , and the N number of working electrodes 121 , 122 , 123 , 124 , 125 , so that the working electrodes 121 , 122 , 123 , 124 , 125) synthesizing graphene on it; it provides a graphene synthesis method, including.

The descriptions of the first counter electrode 111 , the second counter electrode 112 , the N working electrodes 121 , 122 , 123 , 124 , 125 , and the electrolyte 130 refer to the above description.

For example, by applying the voltage, a direct current of 0.1 to 5A may flow. For example, when the voltage is applied, the voltage value may vary according to the current by using a constant current.

Hereinafter, the effect of the graphene synthesizing apparatus according to an embodiment of the present invention will be described through examples.

Example

Example 1

Using two graphite electrodes as working electrodes and two stainless steel electrodes as counter electrodes, placing the working electrodes between the two counter electrodes, the electrolyte was 0.1M (NH ₄ ) ₂ SO ₄ was used. Each electrode was immersed in the electrolyte, and a constant current of 0.5A was applied to the graphite electrode for 2 hours while the distance between the electrodes was maintained at 2.5 cm to peel the graphite, followed by filtering and washing using a vacuum filtration device. As a result, 2.1 g of exfoliated graphite was obtained through a total of four electrodes.

Example 2

Three graphite electrodes were used as working electrodes, and two stainless steel electrodes were used as counter electrodes, and after disposing the working electrode between the two counter electrodes, 0.1M (NH ₄ ) ₂ SO ₄ was used as the electrolyte. Each electrode was immersed in the electrolyte, and a constant current of 0.5A was applied to the graphite electrode for 2 hours while the distance between the electrodes was maintained at 2.5 cm to peel the graphite, followed by filtering and washing using a vacuum filtration device. As a result, 3.1 g of exfoliated graphite was obtained through a total of 5 electrodes.

Example 3

Four graphite electrodes were used as working electrodes and two stainless steel electrodes were used as counter electrodes, and after disposing the working electrode between the two counter electrodes, 0.1M (NH ₄ ) ₂ SO ₄ was used as the electrolyte. Each electrode was immersed in the electrolyte, and a constant current of 0.5A was applied to the graphite electrode for 2 hours while the distance between the electrodes was maintained at 2.5 cm to peel the graphite, followed by filtering and washing using a vacuum filtration device. As a result, 4.2 g of exfoliated graphite was obtained through a total of 6 electrodes.

Example 4

Five graphite electrodes were used as working electrodes, and two stainless steel electrodes were used as counter electrodes, and after disposing the working electrodes between the two counter electrodes, 0.1M (NH ₄ ) ₂ SO ₄ was used as the electrolyte. Each electrode was immersed in the electrolyte, and a constant current of 0.5A was applied to the graphite electrode for 2 hours while the distance between the electrodes was maintained at 2.5 cm to peel the graphite, followed by filtering and washing using a vacuum filtration device. As a result, 5.2 g of exfoliated graphite was obtained through a total of 7 electrodes.

Comparative Example 1

Using two graphite electrodes as working electrodes and three stainless steel electrodes as counter electrodes, three counter electrodes and two working electrodes were alternately arranged, and the electrolyte was 0.1M (NH ₄ ) ₂ SO ₄ . was used. Each electrode was immersed in the electrolyte, and a constant current of 0.5A was applied to the graphite electrode for 2 hours while the distance between the electrodes was maintained at 2.5 cm to peel the graphite, followed by filtering and washing using a vacuum filtration device. As a result, through a total of five electrodes, 2.0 g of exfoliated graphite was obtained.

Comparative Example 2

Using 3 graphite electrodes as working electrodes and 4 stainless steel electrodes as counter electrodes, 4 counter electrodes and 3 working electrodes were alternately arranged, and the electrolyte was 0.1M (NH ₄ ) ₂ SO ₄ . was used. Each electrode was immersed in the electrolyte, and a constant current of 0.5A was applied to the graphite electrode for 2 hours while the distance between the electrodes was maintained at 2.5 cm to peel the graphite, followed by filtering and washing using a vacuum filtration device. As a result, 2.9 g of exfoliated graphite was obtained through a total of 7 electrodes.

The number of electrodes used in Examples 1 to 4 and Comparative Examples 1 to 2 and the amount of exfoliated graphite obtained were compared and shown in Table 1 below.

number of electrodes
(Number of working electrodes) exfoliated graphite (g) number of electrodes
(Number of working electrodes) exfoliated graphite (g) Example 1 4(2) 2.1 Comparative Example 1 5(2) 2.0 Example 2 5(3) 3.1 Comparative Example 2 7(3) 2.9 Example 3 6(4) 4.2 Example 4 7(5) 5.2

Referring to Table 1, when Example 2 and Comparative Example 1, and Example 3 and Comparative Example 2 using the same number of electrodes were compared, the amount of exfoliated graphite obtained in Examples 2 and 3, respectively, was significantly higher can confirm.

In addition, in Example 1, in which the number of electrodes was smaller than in Comparative Example 1, the amount of exfoliated graphite was greater than in Comparative Example 1, and Examples 2 and 3, in which the number of electrodes were smaller than in Comparative Example 2, also showed the amount of exfoliated graphite more than in Comparative Example 2.

Furthermore, even when comparing Example 1 and Comparative Example 1 with the same number of working electrodes, and Example 2 and Comparative Example 2, it was confirmed that the amount of exfoliated graphite obtained in Examples 1 and 2 with a smaller total number of electrodes was larger. can

As described above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited thereto, and the technical spirit of the present invention and the following by those of ordinary skill in the art to which the present invention pertains. It goes without saying that various modifications and variations are possible within the scope of equivalents of the claims to be described.

Claims (9)

a reaction chamber defining a space in which graphene is synthesized;
a first counter electrode disposed inside the reaction chamber;
a second counter electrode disposed inside the reaction chamber to face the first counter electrode; and
including N working electrodes (wherein N is an integer of 2 or more) disposed with a predetermined interval between the first counter electrode and the second counter electrode;
the first counter electrode is electrochemically connected to each of the N working electrodes;
The second counter electrode is electrochemically connected to each of the N working electrodes, and graphene is synthesized on the working electrode. delete According to claim 1,
The first counter electrode and the second counter electrode are, independently of each other, a metal electrode or a graphite electrode, a graphene synthesis device. According to claim 1,
The N working electrodes are graphite electrodes, graphene synthesis device. According to claim 1,
The first counter electrode, the second counter electrode, and the N working electrodes are, independently of each other, in the form of a sheet, a foil or a plate, graphene synthesis apparatus. According to claim 1,
Further comprising an electrolyte inside the reaction chamber, graphene synthesis device. 7. The method of claim 6,
The electrolyte is sulfate (SO ₄ ^2- ), nitrate (NO ₃ ^- ), phosphate (PO ₄ ^3- ), metal halide, ionic liquids (ionic liquids), or a combination thereof, graphene synthesis device comprising. introducing an electrolyte into the reaction chamber;
disposing a first counter electrode and a second counter electrode to face each other in the electrolyte;
disposing N working electrodes (wherein N is an integer of 2 or more) with a predetermined interval between the first counter electrode and the second counter electrode;
electrochemically connecting the first counter electrode to each of the N working electrodes and electrochemically connecting the second counter electrode to each of the N working electrodes; and
synthesizing graphene on the working electrode by applying a voltage to the first counter electrode, the second counter electrode, and the N working electrodes. 9. The method of claim 8,
By applying the voltage, a direct current of 0.1 to 5A flows, graphene synthesis method.

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