CARBON COMPLEX AND METHOD FOR MANUFACTURING THE SAME

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2024-0115084, filed on Aug. 27, 2024, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE DISCLOSURE

Field of the Disclosure

The present disclosure relates to a carbon composite and a method of manufacturing the same. More particularly, the present disclosure relates to a carbon composite in which a metal layer including at least one of a metal, a metal oxide, and a metal carbide is formed on the surface of a carbon material, and a method of manufacturing the same.

Description of the Related Art

Carbon materials are highly valuable materials applicable in a wide range of industries such as catalysts, fuel cells, secondary battery electrode materials, supercapacitors, composites, gas sensors, solar cells, chemical plants, desalination devices, and natural gas reformers, and they have been applied in various forms.

Activated carbon, which has high conductivity, excellent mechanical properties, and a very large specific surface area, has been extensively studied as an electrode material for fuel cells and secondary batteries due to its high porosity and stable carbon characteristics. It has also attracted attention as a separation matrix for storing gaseous fuels such as hydrocarbons and hydrogen, or for purifying harmful gases such as carbon dioxide in contaminated regions.

Materials obtained by mixing carbon materials with high thermal conductivity (such as diamond, graphite, carbon black, and carbon nanotubes) and polymers are used as heat dissipation materials for controlling heat generation in electronic products and components. As modern electronic devices become more precise, miniaturized, and highly integrated, localized heat generation becomes more severe. Such heat generation not only reduces the efficiency and performance of electronic components but also raises serious concerns about the stability of semiconductors, thereby further highlighting the importance of heat dissipation materials.

Carbon fiber-reinforced composites have high rigidity while being lightweight, and thus their use has been expanded in various fields such as structural materials for aircraft, automotive structures, and sporting goods. In particular, in applications where conductivity or electromagnetic shielding properties are required (for example, primary aircraft structures requiring electromagnetic shielding to prevent damage caused by lightning during flight, or automotive ECU cases requiring electromagnetic shielding to prevent malfunction of sensors), the application fields are expanding to include carbon fiber-reinforced metal composites that are made by combining carbon fibers with metals.

Electrodes of lithium secondary batteries are mainly made of carbon materials with large surface areas. However, when such carbon materials are used alone as electrodes, there is a limitation in energy density, and the charge/discharge efficiency is poor. Therefore, research has been conducted on functionalization to overcome these difficulties.

As reviewed above, with the diversification of application forms of carbon materials, the functionalization of carbon materials is attracting increasing attention as an important characteristic. Accordingly, there is a continuous demand for the development of surface modification technologies that may impart various functions to the surfaces of carbon materials. However, current methods for introducing functional materials onto the highly hydrophobic surface of carbon materials mostly rely on surface treatment techniques that generate defects on the surface of the carbon material, or methods that involve complex manufacturing processes and require high production costs. Therefore, there is a need for a surface modification method that can reduce manufacturing costs and simplify the manufacturing process.

SUMMARY OF THE DISCLOSURE

Therefore, the present disclosure has been made in view of the above problems, and it is an object of the present disclosure to provide a carbon composite and a method of manufacturing the carbon composite. More specifically, the present disclosure aims to provide a carbon composite in which a metal layer is uniformly formed on the surface of a carbon material.

It is another object of the present disclosure to provide a method of controlling the composition of a metal layer formed on a carbon composite. More specifically, the present disclosure aims to provide a method capable of selectively controlling the composition of the metal layer to include at least one selected from the group consisting of a metal, a metal oxide, and a metal carbide.

It is still another object of the present disclosure to provide a method of adjusting the thickness of a metal layer formed on a carbon composite.

In accordance with an aspect of the present disclosure, the above and other objects can be accomplished by the provision of a method of manufacturing a carbon composite, the method including: preparing a carbon dispersion solution by dispersing a carbon material and an ionic amphipathic molecule in a polar solvent; mixing a metal precursor in the carbon dispersion solution to prepare a carbon-metal dispersion solution; obtaining a carbon-metal ion complex from the carbon-metal dispersion solution; and forming a metal layer on a surface of the carbon material by heat-treating the carbon-metal ion complex, wherein the metal layer includes at least one selected from the group consisting of a metal, a metal oxide, and a metal carbide, and the carbon-metal ion complex is bound by electrostatic attraction between the ionic amphipathic molecule coated on the surface of the carbon material and a metal ion or ionic metal complex included in the metal precursor.

Due to the heat treatment in the forming of the metal layer, at least one reaction selected from thermal oxidation, carbothermal reduction, and carbonization of the metal ion or the ionic metal complex may be carried out.

In the forming of the metal layer, a temperature or method of the heat treatment may be controlled such that the metal layer selectively includes at least one selected from the group consisting of a metal, a metal oxide, and a metal carbide.

The heat treatment temperature may range from 300° C. to 2,000° C.

The heat treatment method may include at least one selected from furnace heat treatment, laser treatment, white light treatment, Joule heating, microwave heat treatment, and plasma heat treatment.

The intensity of the laser treatment may range from 0.5 W to 20 W.

A scanning speed of the laser treatment may range from 50 mm/s to 1,500 mm/s.

In the preparing of the carbon dispersion solution, the content of the ionic amphipathic molecule may range from 2 to 80 parts by weight based on 100 parts by weight of the carbon material.

The ionic amphipathic molecule may be a polymer or monomer including a functional group selected from the group consisting of amine, ammonium, carboxylic acid, sulfonic acid, sulfate, hydroxyl, thiol, and ketone.

The metal precursor may include at least one selected from the group consisting of copper (Cu), nickel (Ni), iron (Fe), zinc (Zn), tin (Sn), silver (Ag), titanium (Ti), aluminum (Al), molybdenum (Mo), zirconium (Zr), indium (In), tungsten (W), vanadium (V), chromium (Cr), niobium (Nb), tantalum (Ta), and hafnium (Hf).

The obtaining of the carbon-metal ion complex may be performed by a centrifugation method or a wet coating method.

The metal layer may be adjusted to have a thickness of 10 nm to 1 μm.

In accordance with another aspect of the present disclosure, provided is a carbon composite manufactured by the method, wherein the carbon composite includes: a carbon material; and a metal layer formed on a surface of the carbon material, wherein the metal layer includes at least one selected from the group consisting of a metal, a metal oxide, and a metal carbide.

The metal layer may have a thickness of 10 nm to 1 μm.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a flowchart illustrating a method for manufacturing a carbon composite according to one embodiment of the present disclosure;

FIG. 2 illustrates the schematic cross-sectional view of a carbon composite according to another embodiment of the present disclosure;

FIG. 3 illustrates the results of energy dispersive spectroscopy (EDS) analysis of a carbon-metal ion complex prepared according to Comparative Example 3;

FIG. 4 illustrates the results of energy dispersive spectroscopy analysis of a carbon-metal ion complex prepared according to Comparative Example 4;

FIGS. 5 to 8 illustrate the results of EDS analysis of carbon-metal ion complexes prepared according to Comparative Examples 5 to 8; and

FIG. 9 illustrates the results of X-ray diffraction (XRD) analysis for confirming the composition of a metal layer formed in a carbon composite prepared according to Examples 1 to 4.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure will now be described more fully with reference to the accompanying drawings and contents disclosed in the drawings. However, the present disclosure should not be construed as limited to the exemplary embodiments described herein.

The terms used in the present specification are used to explain a specific exemplary embodiment and not to limit the present inventive concept. Thus, the expression of singularity in the present specification includes the expression of plurality unless clearly specified otherwise in context. It will be further understood that the terms “comprise” and/or “comprising”, when used in this specification, specify the presence of stated components, steps, operations, and/or elements, but do not preclude the presence or addition of one or more other components, steps, operations, and/or elements thereof.

It should not be understood that arbitrary aspects or designs disclosed in “embodiments”, “examples”, “aspects”, etc. used in the specification are more satisfactory or advantageous than other aspects or designs.

In addition, the expression “or” means “inclusive or” rather than “exclusive or”. That is, unless otherwise mentioned or clearly inferred from context, the expression “x uses a or b” means any one of natural inclusive permutations.

In addition, as used in the description of the disclosure and the appended claims, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless context clearly indicates otherwise.

Further, when an element such as a layer, a film, a region, and a constituent is referred to as being “on” another element, the element can be directly on another element or an intervening element can be present.

Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

FIG. 1 is a flowchart illustrating a method for manufacturing a carbon composite according to one embodiment of the present disclosure.

Referring to FIG. 1, the method of manufacturing a carbon composite according to an embodiment of the present disclosure may include: a step (S110) of dispersing a carbon material and an ionic amphipathic molecule in a polar solvent to prepare a carbon dispersion solution; a step (S120) of mixing a metal precursor in the carbon dispersion solution to prepare a carbon-metal dispersion solution; a step (S130) of obtaining a carbon-metal ion complex from the carbon-metal dispersion solution; and a step of (S140) heat-treating the carbon-metal ion complex to form a metal layer on the surface of the carbon material.

The metal layer may include at least one selected from the group consisting of a metal, a metal oxide, and a metal carbide, and the carbon-metal ion complex may be formed by electrostatic attraction between an ionic amphipathic molecule coated on the surface of the carbon material and a metal ion or ionic metal complex included in the metal precursor. Here, the ionic metal complex refers to a structure in which a central metal ion is coordinated with an anion or a molecule, wherein the central metal ion may be a transition metal ion carrying a cationic charge, and the anion or molecule bonded to the central metal ion may have at least one lone electron pair.

Hereinafter, the method of manufacturing a carbon composite will be described in greater detail.

The method of manufacturing a carbon composite includes a step (S110) of preparing a carbon dispersion solution.

The step (S110) of preparing a carbon dispersion solution involves dispersing a carbon material and an ionic amphipathic molecule in a polar solvent, and a surface modification reaction occurs in which the ionic amphipathic molecule is coated on the surface of the carbon material. The ionic amphipathic molecule is composed of a hydrophilic functional group carrying a charge and a hydrophobic chain, and when mixed with the carbon material, the chain portion is arranged along the surface of the carbon material, while the charged functional group is oriented toward the solution. As a result, the surface of the carbon material may be induced to have hydrophilic groups, enabling the carbon material to be uniformly dispersed in the polar solvent.

The polar solvent used in the carbon dispersion solution may include water. In the step (S110) of preparing a carbon dispersion solution, an organic solvent is not used as a solvent, so that no post-treatment process for handling an organic solvent is required during the manufacturing process, thereby providing cost reduction and prevention of environmental pollution.

In the step (S110) of preparing a carbon dispersion solution, ultrasonic waves may be used as a method for dispersing a carbon material and an ionic amphipathic molecule. Specifically, the carbon material and the ionic amphipathic molecule may be added to the solvent, and ultrasonic waves may be applied thereto, so that the carbon material and the ionic amphipathic molecule are uniformly dispersed in the solvent. In this case, the time for applying ultrasonic waves may range from 1 minute to 60 minutes.

The step (S110) of preparing a carbon dispersion solution may be performed at a temperature of 4° C. to 100° C. If an organic solvent is used as the solvent in the step (S110) of preparing a carbon dispersion solution, there arises a problem that the preparation must be carried out at a high temperature exceeding 100° C., thereby causing significant process costs. According to the method of manufacturing a carbon composite of an embodiment of the present disclosure, the preparation may be performed at a low temperature below 100° C., thereby achieving cost reduction.

In the step (S110) of preparing a carbon dispersion solution, the carbon material may be selected from the group consisting of carbon nanotubes (CNT), graphite, graphene, activated carbon, mesoporous carbon, carbon black, carbon nanofiber, and carbon nanowires.

In the step (S110) of preparing a carbon dispersion solution, the ionic amphipathic molecule may be a polymer or monomer containing a functional group selected from the group consisting of amine, ammonium, carboxylic acid, sulfonic acid, sulfate, hydroxyl, thiol, and ketone.

Among ionic amphipathic molecules, ionic amphipathic molecules having a positive charge may be polymers or monomers having an amine or ammonium functional group, and specifically, may include one selected from the group consisting of polyethyleneimine, polyacrylamide, polyallylamine, hexadimethrine, cetrimonium, poly(diallyldimethylammonium), and dodecyltrimethylammonium.

An ionic amphipathic molecule having a negative charge may be a polymer or monomer containing a functional group selected from the group consisting of carboxylic acid, sulfonic acid, sulfate, hydroxyl, thiol, and ketone, but is not limited thereto.

Specific examples of ionic amphipathic molecules having a negative charge may include one selected from the group consisting of polyacrylic acid, carboxymethylcellulose, polystyrenesulfonate, polyvinylsulfonate, dodecyl benzenesulfonate, dodecyl sulfate, polypropylene glycol, polyethylene glycol, poly(ethylene glycol) methyl ether thiol, ethyl acetoacetate, and polyvinylpyrrolidone (PVP), but are not limited thereto.

In the step (S110) of preparing a carbon dispersion solution, the content of the ionic amphipathic molecule may be 2 to 80 parts by weight per 100 parts by weight of the carbon material. The ionic amphipathic molecule serves to increase the dispersibility of the carbon material in the polar solvent. Accordingly, when used in an amount less than 2 parts by weight, it may be difficult to uniformly disperse the carbon material in the polar solvent, leading to aggregation. When used in an amount exceeding 80 parts by weight, the adsorption behavior of the metal ion or ionic metal complex onto the ionic amphipathic molecule may be restricted.

The step (S120) of preparing a carbon-metal dispersion solution may be carried out by adding a metal precursor to the carbon dispersion solution and stirring it.

In the step (S120) of preparing a carbon-metal dispersion solution, a reaction may occur in which the ionic amphipathic molecule coated on the surface of the carbon material in the step (S110) of preparing a carbon dispersion solution is bound to a metal ion or ionic metal complex included in the metal precursor by electrostatic attraction.

When a cationic amphipathic molecule is used, a hydrophilic functional group carrying a positive charge may be arranged on the surface of the carbon material, so that the cationic amphipathic molecule may adsorb a metal anion or an anionic metal complex. When an anionic ionic amphipathic molecule is used, the hydrophilic functional group carrying a negative charge may be arranged on the surface of the carbon material, such that the anionic ionic amphipathic molecule may adsorb a metal cation or a cationic metal complex.

The step (S120) of preparing a carbon-metal dispersion solution may, like the step (S110) of preparing a carbon dispersion solution, be performed at a temperature in the range of 4° C. to below 100° C., and stirring may be performed for at least 5 minutes to achieve uniform adsorption.

At a temperature below 4° C., the adsorption behavior of the ionic amphipathic molecule and the metal ion or the ionic metal complex may be restricted, while at a temperature exceeding 100° C., the thermal behavior of molecules and ions may be activated, making uniform adsorption difficult.

The metal precursor may include at least one selected from the group consisting of copper (Cu), nickel (Ni), iron (Fe), zinc (Zn), tin (Sn), silver (Ag), titanium (Ti), aluminum (Al), molybdenum (Mo), zirconium (Zr), indium (In), tungsten (W), vanadium (V), chromium (Cr), niobium (Nb), tantalum (Ta), and hafnium (Hf).

Specific examples of the metal precursor may include copper (II) nitrate, copper acetate, copper (II) sulfate, copper (II) chloride, copper (II) acetylacetonate, nickel (II) nitrate, nickel (II) acetate, nickel (II) sulfate, nickel (II) chloride, nickel (II) acetylacetonate, iron (III) nitrate, iron (III) chloride, iron (III) acetate, iron (II) sulfate, zinc (II) nitrate, zinc (II) chloride, zinc (II) acetate, zinc (II) sulfate, tin (IV) acetate, tin (II) chloride, tin (II) acetylacetonate, silver nitrate, silver acetate, silver sulfate, silver chloride, silver acetylacetonate, titanium (IV) chloride, aluminum (III) nitrate, aluminum (III) chloride, aluminum (III) sulfate, ammonium heptamolybdate, molybdenum (III) chloride, zirconium (IV) chloride, indium (III) nitrate, indium (III) chloride, indium (III) acetate, sodium tungstate, tungsten (IV) chloride, ammonium metatungstate, ammonium metavanadate, vanadyl sulfate, vanadium (III) nitrate, ammonium dichromate, chromium (III) nitrate, chromium (III) chloride, chromium (III) acetate, chromium (III) sulfate, niobium (V) chloride, tantalum (V) chloride, and hafnium (IV) chloride, but are not limited thereto.

The step (S130) of obtaining a carbon-metal ion complex may be performed by a centrifugation method or a wet coating method.

In the step (S120) of preparing a carbon-metal dispersion solution, when the ionic amphipathic molecule coated on the surface of the carbon material is bound to a metal ion or ionic metal complex included in the metal precursor by electrostatic attraction, a carbon-metal ion complex is formed. Since the metal ion or ionic metal complex formed in the carbon-metal ion complex is bound by weak electrostatic attraction, a subsequent step may be required to more firmly bind the metal ion or ionic metal complex to the surface of the carbon material.

The step (S130) of obtaining a carbon-metal ion complex may include obtaining the prepared carbon-metal ion complex by centrifugation or a wet coating method, and may further include a process of removing excess ionic amphipathic molecule substances or metal precursors that remain unadsorbed on the surface of the carbon material. The process of removing the excess ionic amphipathic molecule substances or metal precursors may be carried out by discarding the supernatant after centrifugation.

When the centrifugation method is used, the process may further include drying the precipitated particles, wherein the drying temperature may range from 50° C. to 200° C., and the drying time may range from 10 minutes to 24 hours.

In the step (S130) of obtaining a carbon-metal ion complex, the amount or thickness of the metal ion or ionic metal complex introduced onto the surface of the carbon material may be controlled depending on the method of obtaining the carbon-metal ion complex.

When a centrifugation method is used, since the metal ion or the ionic metal complex is adsorbed onto the ionic functional group of the ionic amphipathic molecule adsorbed on the surface of the carbon material, it may be coated as a thin film.

On the other hand, when a wet coating method is used, the metal ion or the ionic metal complex may be coated over the entire surface of the carbon material during evaporation of the solvent, thereby forming a thick film having a thickness of 100 nm to 1 μm.

Depending on the thickness of the metal ion or ionic metal complex, the ratio of oxidation, reduction, or carbonization reactions of the metal ion or ionic metal complex occurring during heat treatment may vary, and the surface volume fraction of the metal, metal oxide, and metal carbide may be controlled. Therefore, the electromagnetic properties and electrochemical properties of a carbon composite may be controlled by adjusting the method of obtaining the carbon-metal ion complex.

The step (S140) of forming a metal layer may include heat-treating the carbon-metal ion complex obtained in the step (S130) of obtaining a carbon-metal ion complex so as to induce chemical and/or physical bonding between the carbon material and the metal ion or ionic metal complex, thereby strengthening their interaction.

In the carbon-metal ion complex, the metal ion or the ionic metal complex is bound to the surface of the carbon material through electrostatic attraction between the ionic amphipathic molecule coated on the carbon material and the metal ion or ionic metal complex included in the metal precursor. However, in the step (S140) of forming a metal layer, at least one of a redox reaction, thermal oxidation reaction, carbothermal reduction reaction, or carbonization reaction of the metal ion or metal complex bound to the ionic amphipathic molecule may occur through heat treatment. As a result, chemical bonding on the surface of the carbon material may be formed, thereby strengthening the bonding with the surface layer.

In the step (S140) of forming a metal layer, the temperature or method of the heat treatment may be adjusted so that the metal layer formed on the surface of the carbon material selectively includes at least one selected from the group consisting of a metal, a metal oxide, and a metal carbide.

In the step (S140) of forming a metal layer, any one of furnace heat treatment, laser treatment, white light treatment, Joule heating, microwave heat treatment, or plasma heat treatment may be used. Here, furnace heat treatment means a process of heating in a furnace. Joule heating refers to a method of heating a metal body using electromagnetic induction, in which eddy currents are generated in the metal to be heated when a current is supplied to a coil, and the Joule heat generated by the resistance of the metal increases the temperature to transfer heat.

When furnace heat treatment is performed, the heat treatment may be carried out in an inert atmosphere, and the metal layer formed on the surface of the carbon material may include a metal oxide or a metal carbide.

When furnace heat treatment is performed, a thermal oxidation reaction may occur due to trace oxygen, and depending on the heat treatment temperature, a carbothermal reduction reaction and carbonization reaction of the metal oxide may proceed, resulting in the formation of a metal carbide.

More specifically, in laser heat treatment, the amount of energy delivered during the heat treatment process may be controlled by adjusting the intensity (power) or the scanning speed, thereby enabling control over the formation and composition of metal, metal oxide, and metal carbide.

Compared with furnace heat treatment, laser heat treatment may provide a much higher energy supply, such that the carbothermal reduction reaction of the metal oxide, which forms metals, and the carbonization reaction, which forms metal carbides, may occur simultaneously, and since the heat treatment process is carried out in a short time, simultaneous formation of metal, metal oxide, and metal carbide is possible.

Not only laser heat treatment but also white light treatment, Joule heating, microwave heat treatment, and plasma heat treatment may provide an instantaneous supply of very high thermal energy, so that, similar to laser heat treatment, a metal layer selectively including at least one of a metal, a metal oxide, and a metal carbide may be formed.

In the step (S140) of forming a metal layer, the furnace heat treatment temperature may range from 300° C. to 2,000° C.

At a temperature below 300° C., the thermal decomposition and redox reactions of the ionic amphipathic molecule may not sufficiently proceed, so that the metal layer may not be formed, whereas at a temperature exceeding 2,000° C., the metal layer may melt and lose its shape.

In laser treatment, white light treatment, Joule heating, microwave heat treatment, and plasma heat treatment, the heat treatment is carried out for a very short time, so that melting of the metal layer may be limited, but it is preferable to perform the heat treatment at a temperature of 2,500° C. or less.

In the step (S140) of forming a metal layer, the laser treatment intensity (power) may range from 0.5 W to 20 W, and the scanning speed of the laser treatment may range from 50 mm/s to 1,500 mm/s. The scanning speed of the laser may refer to the speed at which the laser irradiation part scans over the metal nanoparticle film.

The optical energy supplied during laser heat treatment is determined by the intensity (power) and scanning speed of the laser treatment. When laser heat treatment is performed with high optical energy and low scanning speed, the carbothermal reduction reaction may be further activated, resulting in the formation of a surface layer containing metal compositions. When laser heat treatment is performed with low optical energy and high scanning speed, the composition may be limited to metals and metal oxides due to the restricted activation of the carbothermal reduction reaction. Therefore, the composition of the surface layer may be controlled depending on the laser treatment process parameters.

In the carbon composite according to one embodiment of the present disclosure, the thickness of the metal layer formed may be adjusted to 10 nm to 1 μm.

When the thickness of the metal layer is less than 10 nm, the formation of a uniform film-shaped metal layer may be limited. When the thickness exceeds 1 μm, residuals may remain because the thermal decomposition and volatilization of the ionic amphipathic molecule may be restricted during the heat treatment process.

Depending on the thickness of the metal layer, the occurrence ratio of thermal oxidation, carbothermal reduction, and carbonization reactions during heat treatment may be controlled, and the volume fraction of the metal, metal oxide, and metal carbide constituting the metal layer may also be controlled. Therefore, thickness control may be important for adjusting the electromagnetic and electrochemical properties of the carbon composite.

FIG. 2 illustrates the schematic cross-sectional view of a carbon composite according to another embodiment of the present disclosure.

Referring to FIG. 2, a carbon composite 200 according to another embodiment of the present disclosure may be manufactured to include a carbon material 210; and the metal layer 220 formed on the surface of the carbon material 210. The metal layer 220 formed on the surface of the carbon material 210 is characterized by including at least one selected from the group consisting of a metal, a metal oxide, and a metal carbide.

As described above in relation to the step of forming the metal layer, the thickness of the metal layer included in the carbon composite may be 10 nm to 1 μm.

Hereinafter, the present disclosure will be described in more detail through examples. These examples are provided to illustrate the present disclosure more specifically, and the scope of the present disclosure is not limited by these examples.

Comparative Example 1

2 g of artificial graphite was added to 250 g of distilled water and stirred, and then dispersed for 30 minutes using an external ultrasonic disperser to prepare a carbon dispersion aqueous solution. 0.12 g of copper sulfate pentahydrate was further added, followed by stirring for 2 hours. The solution was centrifuged at 7000 rpm for 15 minutes, and the precipitated particles were dried at 80° C. for 12 hours.

Comparative Example 2

Comparative Example 2 was prepared in the same manner as Comparative Example 1, except that ammonium molybdate tetrahydrate was used instead of copper sulfate pentahydrate.

Comparative Example 3

Comparative Example 3 was prepared in the same manner as Comparative Example 1, except that multi-walled carbon nanotubes (MWCNTs) were used instead of artificial graphite in the preparation of the carbon dispersion aqueous solution, and 1 g of polyethylene imine (PEI, M.W. 2000) was additionally used.

Comparative Example 4

Comparative Example 4 was prepared in the same manner as Comparative Example 3, except that polyvinylpyrrolidone was used instead of polyethylene imine, and ammonium molybdate tetrahydrate was used instead of copper sulfate pentahydrate.

Comparative Example 5

Comparative Example 5 was prepared in the same manner as Comparative Example 3, except that polyvinylpyrrolidone was used instead of polyethylene imine.

Comparative Example 6

Comparative Example 6 was prepared in the same manner as Comparative Example 3, except that ammonium molybdate tetrahydrate was used instead of copper sulfate pentahydrate.

Comparative Example 7

Comparative Example 7 was prepared in the same manner as Comparative Example 5, except that artificial graphite was used instead of multi-walled carbon nanotubes, and after stirring with copper sulfate pentahydrate, the centrifugation step was replaced with heating to 80° C. and stirring for 24 hours to evaporate the distilled water, thereby obtaining the remaining particles.

Comparative Example 8

Comparative Example 8 was prepared in the same manner as Comparative Example 7, except that polyethylene imine was used instead of polyvinylpyrrolidone, and ammonium molybdate tetrahydrate was used instead of copper sulfate pentahydrate.

Example 1

After the preparation of Comparative Example 8, the molybdenum-adsorbed graphite composite obtained was heat-treated in an argon (Ar) atmosphere at 600° C. for 3 hours to produce Example 1.

Example 2

Example 2 was prepared in the same manner as Example 1, except that the heat treatment temperature was changed to 800° C.

Example 3

Example 3 was prepared in the same manner as Example 1, except that the heat treatment temperature was changed to 1000° C.

Example 4

After the preparation of Comparative Example 8, the molybdenum-adsorbed graphite composite obtained was irradiated with a laser at a power of 3.5 W and a scanning speed of 400 mm/sec under ambient conditions to produce Example 4.

Experimental Example 1: Investigation of Adsorption of Metal Ion or Ionic Metal Complex Depending on Whether Ionic Amphipathic Molecule is Used and Type of Charge of Ionic Amphipathic Molecule During Preparation of Carbon-Metal Ion Complex

For the carbon-metal ion complexes prepared according to Comparative Examples 1 to 4, the adsorption of a metal ion or ionic metal complex on the surface of the carbon material was investigated depending on whether an ionic amphipathic polymer was used.

Comparative Examples 1 and 2 were samples prepared without using an ionic amphipathic polymer. Comparative Example 3 used polyethylene imine, which is a cationic ionic amphipathic polymer, together with copper sulfate pentahydrate containing a cationic metal complex. Comparative Example 4 used polyvinylpyrrolidone, which is an anionic amphipathic polymer, together with ammonium molybdate tetrahydrate containing an anionic metal complex.

[Table 1] shows the results of elemental composition analysis of the carbon-metal ion complexes prepared according to Comparative Examples 1 to 4.

	TABLE 1
	Comparative	Comparative	Comparative	Comparative
	Example 1	Example 2	Example 3	Example 4

	Weight %	Atomic %	Weight %	Atomic %	Weight %	Atomic %	Weight %	Atomic %

C	—	—	—	—	98.53	98.74	98.38	98.61
N	—	—	—	—	1.47	1.26	1.62	1.39
Cu	—	—	—	—	0.00	0.00	—	—
Mo	—	—	—	—	—	—	0.00	0.00
Total	100	100	100	100	100.00	100.00	100.00	100.00

Referring to the results of [Table 1], it can be seen that, in the case of Comparative Examples 1 and 2 where an ionic amphipathic polymer was not used, surface modification of the artificial graphite did not proceed, so the artificial graphite was not dispersed in the solvent, and preparation of the carbon-metal ion complex was impossible.

In the case of Comparative Examples 3 and 4, it can be seen that, although dispersion of the artificial graphite in the solvent was possible by using an ionic amphipathic polymer, the ionic amphipathic polymer and the metal ion or ionic metal complex contained in the metal precursor carried the same charge, so that the adsorption reaction between the ionic amphipathic polymer and the metal ion or the ionic metal complex did not proceed.

The carbon-metal ion complexes prepared according to Comparative Examples 1 to 4 were analyzed using a scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS), and the results are shown in FIGS. 3 and 4.

FIG. 3 illustrates a carbon-metal ion complex prepared according to Comparative Example 3, and FIG. 4 illustrates a carbon-metal ion complex prepared according to Comparative Example 4.

Referring to the results of FIGS. 3 and 4, it can be seen that, in Comparative Examples 3 and 4 where ionic amphipathic polymers carrying the same charge as the metal ion or ionic metal complex contained in the metal precursor were used, the ionic amphipathic polymer was uniformly coated on the surface of the carbon material, but the metal ion or ionic metal complex was not adsorbed.

Experimental Example 2: Observation of Carbon-Metal Ion Complex

The carbon-metal ion complexes prepared according to Comparative Examples 5 to 8 were observed using a scanning electron microscope and energy dispersive spectroscopy.

Comparative Examples 5 and 7 used polyvinylpyrrolidone, which is an anionic amphipathic polymer, together with copper sulfate pentahydrate containing a cationic metal complex, whereas Comparative Examples 6 and 8 used polyethylene imine, which is a cationic amphipathic polymer, together with ammonium molybdate tetrahydrate containing an anionic metal complex.

[Table 2] shows the results of elemental composition analysis of the carbon-metal ion complexes prepared according to Comparative Examples 5 to 8.

	TABLE 2
	Comparative	Comparative	Comparative	Comparative
	Example 5	Example 6	Example 7	Example 8

	Weigh %t	Atomic %	Weight %	Atomic %	Weight %	Atomic %	Weight %	Atomic %

C	97.14	97.68	98.31	99.00	99.04	95.36	99.00	99.58
N	2.65	2.28	1.08	0.93	0.69	0.59	0.39	0.34
Cu	0.21	0.04	—	—	0.27	0.05	—	—
Mo	—	—	0.61	0.07	—	—	0.61	0.08
Total	100.00	100.00	100.00	100.00	100.00	100.00	100.00	100.00

Referring to the results of [Table 2], the carbon-metal ion complexes prepared according to Comparative Examples 5 to 8 had the ionic amphipathic polymer uniformly coated on the surface of the carbon material, which indicates that the carbon material was uniformly dispersed in the solvent.

In addition, the carbon-metal ion complexes prepared according to Comparative Examples 5 to 8 showed that the ionic amphipathic polymer and the metal ion or ionic metal complex contained in the metal precursor had opposite charges, and that the metal ion or ionic metal complex was adsorbed onto the ionic amphipathic polymer.

This demonstrates that the adsorption of a metal ion or an ionic metal complex onto the surface of the carbon material in the carbon-metal ion complex is due to the electrostatic attraction between the ionic amphipathic polymer and the metal ion or ionic metal complex contained in the metal precursor.

The carbon-metal ion complexes prepared according to Comparative Examples 5 to 8 were analyzed by energy dispersive spectroscopy (EDS), and the results are shown in FIGS. 5 to 8.

FIGS. 5 to 8 illustrate the results of EDS analysis of the carbon-metal ion complexes prepared according to Comparative Examples 5 to 8.

Referring to the results of FIGS. 5 to 8, it can be seen that the ionic amphipathic polymer was uniformly coated on the surface of the carbon material. It was also confirmed that the metal ion or ionic metal complex was adsorbed onto the portion where the ionic amphipathic polymer was coated.

That is, the carbon-metal ion complexes prepared according to Comparative Examples 5 to 8 confirmed that the adsorption of the metal ion or ionic metal complex onto the surface of the carbon material occurred through bonding caused by the electrostatic attraction between the ionic amphipathic polymer and the metal ion or ionic metal complex contained in the metal precursor.

Experimental Example 3: Confirmation of Composition of Metal Layer of Carbon Composite Formed Depending on Heat Treatment Temperature and Method

X-ray diffraction (XRD) analysis was conducted to confirm the composition of the metal layer formed in the carbon composites prepared according to Examples 1 to 4, and the results are shown in FIG. 9.

FIG. 9 illustrates the results of the XRD analysis of Examples 1 to 4.

Referring to the results of FIG. 9, it can be confirmed that the composition of the metal layer is adjusted depending on the heat treatment temperature and method. More specifically, in Example 1 at a heat treatment temperature of 600° C. and Example 2 at a heat treatment temperature of 800° C., the decomposition of the metal ion or ionic metal complex, and oxidation due to trace oxygen occurred during heat treatment, so that the metal layer was composed of a metal oxide. However, in Example 3 at a heat treatment temperature of 1000° C., a carbothermal reduction reaction and a carbonization reaction proceeded even though a metal oxide was formed, resulting in the metal layer being composed of a metal carbide.

In addition, in the case of Example 4 subjected to laser treatment, a metal oxide was formed, and both the carbothermal reduction reaction and carbonization reaction of the metal oxide proceeded. However, since the heat treatment was instantaneous, the carbothermal reduction and the carbonization reactions were limited, resulting in the formation of a metal layer including all of a metal, a metal oxide, and a metal carbide.

In the present disclosure, by modifying the hydrophobic surface of a carbon material with an ionic amphipathic molecule, a metal layer can be uniformly formed on the surface of the carbon material where the introduction of metallic substances is otherwise difficult.

In the present disclosure, by adjusting the temperature and method of heat treatment, the composition of the metal layer formed on the surface of the carbon material can be controlled to selectively include at least one of a metal, a metal oxide, and a metal carbide. Thus, the high surface electrical conductivity of metals and metal carbides, the high dielectric and magnetic properties due to metal oxides, and the electrochemical activity due to metal carbides and metal oxides can all be simultaneously controlled.

In the present disclosure, by controlling the thickness of the metal layer formed on the surface of the carbon material, the surface volume fraction of the metal, metal oxide, and metal carbide included in the metal layer can be adjusted, and the electromagnetic properties of a carbon composite can be controlled through the design of the composition of the carbon material and the metal layer.

Although the present disclosure has been described through limited examples and drawings, the present disclosure is not intended to be limited to the examples. Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the disclosure. Therefore, the scope of the present disclosure should not be limited to the described examples, but should be defined not only by the claims described below but also by equivalents of these claims.