KR20190082558A - manufacturing method of 0-dimensional and 1-dimensional graphene composite catalyst containing nitrogen-iron and fuel cell application - Google Patents

Abstract

The present invention is to provide a method for manufacturing a 0-dimensional and 1-dimensional graphene composite catalyst containing nitrogen-iron and applications to a fuel cell. The method for manufacturing a catalyst comprises: peeling a stacked-cup carbon nanofiber and forming carbon powder; mixing the carbon powder with an iron precursor, a nitrogen precursor and a solvent, freeze-drying the same and forming mixed powder; and thermally treating the mixed powder. The carbon powder comprises 0-dimensional graphene nanoflakes and 1-dimensional graphene nanoribbon. According to the present invention, the catalyst manufactured by the method is not poisoned.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a zero-dimensional and one-dimensional graphene composite catalyst containing nitrogen and iron,

The present invention relates to a method for preparing a zero-dimensional and one-dimensional graphene composite catalyst containing nitrogen and iron and its application to a fuel cell, and more particularly, Dimensional graphene structure composite catalyst for a fuel cell.

A fuel cell is a power generation type cell which converts the chemical reaction energy of hydrogen and oxygen directly into electric energy. Unlike a general battery, as long as hydrogen and oxygen are supplied from the outside, electricity can be continuously produced. Unlike conventional power generation methods, which can generate electricity, the efficiency is twice as high as that of internal combustion engines.

In addition, the polymer electrolyte fuel cell is a fuel cell that uses a polymer membrane having hydrogen ion exchange characteristics as an electrolyte. The polymer electrolyte fuel cell includes a solid polymer electrolyte fuel cell (SPEFC), a solid polymer fuel cell (SPFC), and a polymer electrolyte membrane fuel cell It has an energy conversion efficiency superior to that of other types of fuel cells and has a merit that a high current density and an output density can be obtained even at a low temperature. In addition, it has a short startup time and a fast response to load change. Therefore, the present invention can be applied to various fields such as power supply for electric vehicles, mobile use, military use, home use, and the like.

The main components of the polymer electrolyte fuel cell are a polymer electrolyte membrane, an electrode, and a separator to form a stack. In particular, a membrane-electrode assembly (MEA) in which an anode and a cathode are adhered to a polymer electrolyte membrane by a hot-pressing method is called a membrane-electrode assembly (MEA) .

The MEA of the fuel cell is manufactured with a structure in which the electrodes are widely spread with a thin electrolyte interposed therebetween. Particularly, the electrode is made into a porous structure using fine particles so that the electrolyte and the gas penetrate from both sides to form a three-phase interface at a wide area.

The electrode for a polymer electrolyte fuel cell consists of a catalyst layer and a support for supporting the catalyst layer.

This fuel cell supplies hydrogen to the anode, supplies oxygen to the cathode, and the catalysts in the anode oxidize hydrogen or methanol to form a proton. After passing through the proton conducting membrane, the cathode reduces the reaction with oxygen by the catalysts, Production.

Electrode catalysts are needed to allow oxidation and reduction reactions of the elec- trolyte cells to occur at useful rates and potentials.

However, the platinum catalyst is an expensive precious metal, and has the highest price specific gravity among the components and materials constituting the fuel cell system, and the CO tolerance in the reaction gas is low.

Therefore, in order to mass-produce and commercialize a platinum catalyst, which accounts for a large portion of the total fuel cell production cost, there is a need for lowering the amount of platinum used and developing a commercially viable and highly active platinum substitute catalyst It is getting higher.

Korean Patent Publication No. KR 2014-0075918

SUMMARY OF THE INVENTION The present invention provides a method for preparing a zero-dimensional and one-dimensional graphene composite catalyst containing nitrogen and iron, and a technique for application to a fuel cell.

More specifically, it is intended to provide a catalyst containing nitrogen-iron capable of reducing the production cost, and to provide such a catalyst to increase the oxygen reduction activity without poisoning and to apply the catalyst to a fuel cell.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. There will be.

In order to accomplish the above object, one embodiment of the present invention provides a method for preparing a zero-dimensional and one-dimensional graphene composite catalyst containing nitrogen and iron and a technique for application to a fuel cell. The method for preparing the composite catalyst comprises the steps of forming a carbon powder by peeling a stacked cup carbon nanofiber, mixing the carbon powder with an iron precursor, a nitrogen precursor and a solvent, followed by lyophilization to obtain a mixed powder And heat treating the mixed powder. The carbon powder may include a zero-dimensional graphene nanoflake and a one-dimensional graphene nanoribbons.

The stacked-cup carbon nanofibers are stacked cup-shaped carbon and stacked-cup carbon nanofibers surrounded by a few graphitic walls. Structure.

The iron precursor may be iron sulfate or iron carbide.

The nitrogen precursor may also include dicyandiamide, pyrrole, aniline, urea, protealocyanine, porphyrin, acetonitrile, cyanamide, dicyanamide, acrylonitrile or polyacrylonitrile .

Further, the solvent is characterized by containing water, purified water, ethanol, or propyl alcohol.

The lyophilization step is performed at a temperature of -40 ° C to -30 ° C.

Also, the temperature of the heat treatment step is 800 ° C to 900 ° C.

Further, the heat treatment step is performed in an argon gas atmosphere.

In order to achieve the above-described technique, another embodiment of the present invention provides a composite catalyst prepared by the above-described method for producing a composite catalyst.

In order to achieve the above-described technology, another embodiment of the present invention provides a membrane-electrode bonding agent comprising a catalyst prepared by the above-mentioned method for producing a composite catalyst.

In order to achieve the above-described technology, another embodiment of the present invention provides a membrane-electrode assembly comprising a catalyst prepared by the method for producing a complex catalyst according to claim 1 and a platinum catalyst.

In order to achieve the above-described technology, another embodiment of the present invention provides a fuel cell comprising the above-described membrane-electrode bonding agent.

In order to achieve the above-described technique, another embodiment of the present invention provides a method for manufacturing a carbon composite. The carbon composite material manufacturing method includes the steps of forming a carbon powder by peeling a stacked cup carbon nanofiber, laminating the carbon powder and the solvent, lyophilizing the mixture to form a mixed powder, And heat treating the mixed powder, wherein the carbon powder includes 0-dimensional graphene nanoflake and 1-dimensional graphene nanoribbons.

In order to achieve the above-described technology, another embodiment of the present invention provides a carbon composite material produced by the carbon composite material manufacturing method described above.

In order to achieve the above-described technology, another embodiment of the present invention provides an electrode structure comprising the carbon composite material described above.

According to the embodiment of the present invention, the catalyst produced through the above-described catalyst production method can provide the effect of not being poisoned.

In addition, a zero-dimensional and one-dimensional structure composite catalyst containing nitrogen-iron can provide the effect of producing less by-products of the oxidation-reduction reaction.

In addition, the zero-dimensional structure complex catalyst containing nitrogen-iron can provide an effect of increasing the oxygen reduction activity of the catalyst by decreasing the work function due to its small size.

In addition, since the one-dimensional structural composite catalyst containing nitrogen-iron is formed in a porous structure, the movement of electrons, reactants and products can be smoothly performed, thereby increasing the oxygen reduction activity.

In addition, since the conventional noble metal platinum catalyst is not used, the production cost can be reduced and mass production can be achieved.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart showing a method for producing a composite catalyst. FIG.
FIG. 2 is a TEM photograph synthesizing a 0-dimensional-1-dimensional graphene structure composite catalyst containing nitrogen-iron.
FIG. 3 is a graph showing the results of oxygen reduction activity of synthesized catalysts.
4 is a graph showing the hydrogen peroxide production rate and stability in methanol of the synthesized catalysts.
FIG. 5 is a graph of the ultraviolet light electron spectroscopy analysis result.
6 is an SEM photograph and an electrochemical impedance spectroscopy graph of an electrode manufactured using the synthesized catalyst.
7 is a flowchart showing a method for producing a carbon composite material.
8 is a graph showing the oxygen reduction activity of the synthetic catalyst.
9 is a graph showing the stability of the synthetic catalyst.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" (connected, connected, coupled) with another part, it may be referred to as "directly connected" "Is included. Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart showing a method for producing a catalyst.

Referring to FIG. 1, a carbon powder is formed by stripping a stacked cup carbon nanofiber (S100). The carbon powder is mixed with an iron precursor, a nitrogen precursor and a solvent, followed by lyophilization (S200) of forming a mixed powder and a step (S300) of heat-treating the mixed powder.

First, stacked cup-shaped carbon nanofibers are peeled off to form carbon powder (S100).

The carbon powder may include 0-dimensional graphene nanoflake and 1-dimensional graphene nanoribbons.

For example, carbon nanofibers can be stacked-cup carbon nanofibers surrounded by a few graphitic walls.

When the carbon nanofibers are not peeled off, the carbon nanofibers remain in the conventional form, so that the carbon nanofibers are peeled off and the cup-shaped carbon is laminated on the cup-shaped zero-dimensional graphene nanoflake and the stacked cup- The graphite wall may have a carbon powder containing graphene nanoribbons of one-dimensional structure through a peeling process.

Therefore, the zero-dimensional structure of the peeled carbon nanofibers can provide an effect of increasing the oxygen reduction activity of the catalyst by decreasing the work function due to a small size, and the one-dimensional structure of the carbon powder is formed into a porous structure, And the effect of facilitating the movement of the product and increasing the oxygen reduction activity.

Further, the step of forming the carbon powder by peeling may include peeling using the Modified Hummers' method.

Next, the carbon powder is mixed with an iron precursor, a nitrogen precursor, and a solvent, followed by lyophilization to form a mixed powder (S200).

The iron precursor may include iron sulfate or iron carbide.

The nitrogen precursor may also include dicyandiamide, pyrrole, aniline, urea, protealocyanine, porphyrin, acetonitrile, cyanamide, dicyanamide, acrylonitrile or polyacrylonitrile .

Therefore, the iron precursor and the nitrogen precursor may serve to enhance the activity of the catalyst.

In addition, the solvent may be characterized by containing water, purified water, ethanol, or propyl alcohol.

Therefore, the mixture prepared by mixing the carbon powder, the iron precursor, the nitrogen precursor and the solvent can be prepared through a synthesis reaction, and the prepared mixture can be lyophilized.

The temperature of the freeze-drying step may be -196 ° C to 0 ° C.

In the freeze-drying step, a mixed solution in which the powder is mixed with a solvent according to the temperature condition may be prepared as a mixed powder.

Next, the lyophilized mixed powder is heat-treated (S400).

The temperature of the heat treatment step may be 800 ° C to 900 ° C.

If the temperature is higher than 900 ° C in the heat treatment step or lower than 800 ° C in the heat treatment step, the doping of the heteroatom may not be smoothly performed.

The heat treatment may be performed in an argon gas atmosphere.

The heat treatment may be performed in an argon atmosphere so as to prevent oxidation of the carbon powder when the heat treatment is performed in an argon gas atmosphere.

It is possible to provide a membrane-electrode assembly including the composite catalyst prepared by the above-mentioned composite catalyst production method.

The composite catalyst may include a structure in which the membrane-electrode bonding agent includes an anode to which hydrogen fuel is supplied, a cathode to which air is supplied, and an electrolyte layer including a catalyst between the anode and the cathode.

Therefore, the composite catalyst reacts with the supplied gaseous fuel to decompose into hydrogen ions, or the hydrogen ions that pass through the membrane react with oxygen in the air to generate water, and the composite catalyst of the present invention produces It is possible to provide an effect of increasing the activity of oxidation-reduction without using a noble metal platinum catalyst in a zero-dimensional or one-dimensional structure.

Also, it is possible to provide a membrane-electrode assembly including a catalyst prepared by the above-described complex catalyst production method and a platinum catalyst.

Although the catalyst of the present invention can increase the activity of oxidation-reduction without using a platinum catalyst as described above, the catalyst of the present invention and the platinum catalyst can be used together to increase the lifetime of the fuel cell because stability and reliability are poor .

Accordingly, it is possible to provide a membrane-electrode assembly comprising a catalyst prepared by the method of the present invention and a platinum catalyst, thereby providing a membrane-electrode assembly with an increased lifetime.

Also, it is possible to provide a fuel cell including the composite catalyst prepared by the above-described method for producing a composite catalyst, and including the membrane-electrode assembly.

Further, it is possible to provide a fuel cell including a membrane-electrode assembly including the composite catalyst and the platinum catalyst.

The membrane-electrode assembly including the composite catalyst may be included in the fuel cell together with a separator for constituting the stack.

Therefore, the membrane-electrode assembly including the complex catalyst and the fuel cell can provide the effect of increasing the redox activity, reducing the manufacturing cost, and enabling mass production.

Production Example 1

1) Using a Modified Hummers' method, a "stacked-cup carbon nanofiber surrounded by a few graphitic walls" was peeled off to form a carbon powder.

2) A mixture was prepared by mixing 0.5 g of the exfoliated carbon powder, 1 g of dicyandiamide, 77 mg of FeSO ₄ H ₂ O and purified water (DI-water).

3) The mixture was lyophilized at -40 < 0 > C.

4) Fe-N-exCNF catalyst was prepared by heat treatment of the lyophilized mixture powder at 850 ° C for 3 hours by injecting argon gas (50 ml / min).

Production Example 2

1) An Fe-N-ex CNF catalyst prepared in the same manner as in Production Example 1 and a platinum catalyst were mixed at an 80:20 ratio to prepare a mixed catalyst.

Comparative Example 1

1) A Fe-N-CNF catalyst was produced in the same manner as in Production Example 1 except for the peeling process of Production Example 1.

Comparative Example 2

1) Using graphite in place of "stacked-cup carbon nanofiber surrounded by a few graphitic walls" by using the carbon nanotube of Production Example 1, which was prepared in the same manner as in Production Example 1, Fe-N -ExGr catalyst.

FIG. 2 is a TEM photograph synthesizing a 0-dimensional-1-dimensional graphene structure composite catalyst containing nitrogen-iron.

2 (a) is a TEM photograph of Fe-N-CNF prepared in Comparative Example 1. FIG.

2 (b) is a TEM photograph of the Fe-N-exCNF prepared in Production Example 1 in a 0-dimensional structure.

2C is a TEM photograph of a one-dimensional structure of Fe-N-exCNF prepared in Preparation Example 1. FIG.

2 (d) is a TEM photograph of Fe-N-exGr prepared in Comparative Example 2. FIG.

2 (a) and 2 (b) and 2 (c) are compared with each other, it can be seen that the conventional shape is maintained by stack-cup carbon nanofibers surrounded by a few graphitic walls without peeling, B and c of Fig. 2 show that stacked-cup carbon becomes a 0-dimensional graphene nanoflake after peeling, and that the graphitic wall forms a porous structure of a one-dimensional graphene nanoribbon.

Therefore, it is possible to form a zero-dimensional or one-dimensional graphene structure complex through a peeling process to increase oxygen reduction activity due to a small size and to form a porous structure, thereby facilitating smooth movement of electrons, reactants and products, .

Also, referring to FIG. 2 (d), it can be seen that graphite is also peeled off to obtain a graphene shape having a relatively large-sized two-dimensional structure.

Therefore, it can be confirmed that the oxygen reduction activity of the catalyst is increased because the surface area is increased by peeling off from FIG. 2 (b) and FIG. 2 (c)

FIG. 3 is a graph showing the results of oxygen reduction activity of synthesized catalysts.

(Comparative Example 1), b is Fe-N-exGr (Comparative Example 2), c is Fe-N-exCNF (Production Example 1), d is Pt / C (Conventional platinum catalyst), and is an ORR polarization curve graph of the current density value according to the change in potential.

Referring to FIG. 3 (a), the graph a and graph c of the conventional platinum catalyst showed similar values, and a graph and peeling process without peeling process were performed. However, the graphite had better oxygen reduction activity than b It can be confirmed that it has a value indicating

Therefore, it can be confirmed that the effect of the oxygen reduction activity of the catalyst is enhanced through the separation process of the carbon nano-support during the production of the catalyst including nitrogen-iron.

3 (b) is a graph showing that Fe-N-CNF (Comparative Example 1), b is Fe-N-exGr (Comparative Example 2), and c is Fe-N-exCNF And the prepared catalyst was measured under the conditions of oxygen bubbling 0.1 M, HClO ₄ electrolyte, 5 mVs-1 and an electrode rotation speed of 900 rpm.

Referring to FIG. 3 (b), the graph c in FIG. 3 (b) shows a difference in potential from the remaining graphs a to b, and enhances the oxygen reduction activity of the catalyst through the peeling process as in FIG. Can be confirmed.

4 is a graph showing the hydrogen peroxide production rate and stability in methanol of the synthesized catalysts.

Fig. 4 (a) shows a graph of hydrogen peroxide generation rate b according to the electric potential.

4 (a) shows that the Fe-N-exCNF catalyst produced according to Preparation Example 1 produces less than 5% hydrogen peroxide at all potentials, so that the electron transporting water does not decrease. Thus, hydrogen peroxide Can be advantageously used to produce a less catalytic reaction.

In FIG. 4 (b), a represents Fe-N-exCNF catalyst b, which is a conventional Pt / C catalyst, and is a graph of current density over time.

Referring to FIG. 4 (b), when the methanol injection (methanol addition) is performed, the current density of the conventional Pt / C catalyst is lowered and the Fe-N-exCNF catalyst maintains the current density value.

As a result, it can be confirmed that the Fe-N-exCNF catalyst is not poisoned by methanol and can be applied not only to a polymer membrane membrane fuel cell but also to a methanol direct fuel cell, compared with the conventional Pt / C catalyst, C platinum catalyst in the presence of the catalyst.

FIG. 5 is a graph of the ultraviolet light electron spectroscopy analysis result.

FIG. 5A is a graph showing Fe-N-exGr and b is Fe-N-exCNF catalyst and shows intensity values according to kinetic energy.

Referring to FIG. 5, according to ultraviolet light electron spectroscopy analysis, it is confirmed that the zero-dimensional graphene obtained through the peeling process has a low work function due to its small size, and the oxygen reduction activity and the work function of carbon are inversely proportional to each other .

Therefore, it can be confirmed that the carbon nanofibers in the catalyst have a better oxygen reduction activity effect through the peeling process.

6 is an SEM photograph and an electrochemical impedance spectroscopy graph of an electrode manufactured using the synthesized catalyst.

6 (a) shows Fe-N-exGr, (b) shows Fe-N-exCNF, and FIG. 6 FIG. 6 (d) is an electrochemical impedance spectroscopy (EIS) graph of FIG. 6 (c) to FIG. 6 (d) showing Fe-N-exGr and (b) Fe-N-exCNF catalyst.

Referring to FIG. 6, when the resistance of the electrode manufactured and the movement of electrons, reactants, and products was measured after the electrode was manufactured using the catalyst prepared in Preparation Example 1, Electrode is formed and Nyquist and Bode plot analysis graph using the EIS shows that resistance to electron transfer and resistance to reactant and product transfer are low.

Therefore, the one-dimensional graphene catalyst Fe-N-exCNF prepared in Preparation Example 1 has a porous structure to facilitate movement of electrons, reactants, and products, thereby increasing the oxygen reduction activity.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

7 is a flowchart showing a method for producing a carbon composite material.

Referring to FIG. 7, the step of forming a carbon powder by separating the stacked cup-shaped carbon nanofiber (S400), mixing the carbon powder and the solvent, and freeze-drying the mixture to form a mixed powder (S500), and heat treating the mixed powder (S600).

8 is a graph showing the oxygen reduction activity of the synthetic catalyst.

Referring to FIG. 8, there can be seen a graph of the oxygen reduction activity of the mixed catalyst (named Pt / Fe-N-ex CNF) of Preparation Example 2 prepared by mixing the catalyst of the present invention with the platinum catalyst, (Pt / Fe-N-exCNF) obtained by mixing the catalyst of the present invention and the platinum catalyst is superior to the graph of the Pt / C catalyst conventionally used.

9 is a graph showing the stability of the synthetic catalyst.

Referring to FIG. 9, there is shown a stability graph (operating at 0.4 V for 10 hours) of the mixed catalyst (named Pt / Fe-N-exCNF) of Preparation Example 2 prepared by mixing the catalyst of the present invention with the platinum catalyst. The graph of FIG. 9 shows that the stability of the mixed catalyst (Pt / Fe-N-exCNF) obtained by mixing the catalyst of the present invention with the platinum catalyst is superior to that of the conventional Pt / C catalyst.

8 to 9, the stability of the mixed catalyst (Pt / Fe-N-exCNF) mixed with the catalyst of the present invention and the platinum catalyst and the effect of the oxygen reduction activity are superior to those of the conventional Pt / C catalyst Can be confirmed.

The method for producing the carbon composite material is a method of preparing the complex catalyst except for the addition of the iron precursor and the nitrogen precursor in the step (S200) of the above-mentioned method for producing the complex catalyst. In this case, except for the iron precursor and the nitrogen precursor, Carbon composite can be produced.

In addition, the carbon powder of the carbon composite material may be a cup-shaped zero-dimensional structure and a ribbon-shaped one-dimensional structure.

Accordingly, the carbon composite material produced by the carbon composite material production method may be characterized in that the carbon composite material is removed from the conductive material, and the carbon composite material may be included in the fuel cell.

Since the fuel cell including the carbon composite material has an increased zero-dimensional structure and a one-dimensional structure, it can provide an oxygen reducing activity, and can reduce the production cost and mass production of the fuel cell by using no noble metal platinum catalyst Complex can be provided.

According to the embodiment of the present invention, the catalyst produced through the above-described catalyst production method can provide the effect of not being poisoned.

In addition, a zero-dimensional and one-dimensional structure composite catalyst containing nitrogen-iron can provide the effect of producing less by-products of the oxidation-reduction reaction.

In addition, the zero-dimensional structure complex catalyst containing nitrogen-iron can provide an effect of increasing the oxygen reduction activity of the catalyst by decreasing the work function due to its small size.

In addition, since the one-dimensional structural composite catalyst containing nitrogen-iron is formed in a porous structure, the movement of electrons, reactants and products can be smoothly performed, thereby increasing the oxygen reduction activity.

In addition, since the conventional noble metal platinum catalyst is not used, the production cost can be reduced and mass production can be achieved.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (16)

Peeling the stacked cup carbon nanofibers to form carbon powder;
Mixing the carbon powder with an iron precursor, a nitrogen precursor, and a solvent, followed by lyophilization to form a mixed powder; And
And heat treating the mixed powder,
Wherein the carbon powder comprises 0-dimensional graphene nanoflake and 1-dimensional graphene nanoribbons. The method according to claim 1,
The stacked-cup carbon nanofibers are stacked-cup carbon nanotubes and stacked-cup carbon nanofibers surrounded by a few graphitic walls. ≪ / RTI > The method according to claim 1,
Wherein the iron precursor comprises iron sulfate or iron carbide. The method according to claim 1,
Characterized in that said nitrogen precursor comprises dicyandiamide, pyrrole, aniline, urea, protealocyanine, porphyrin, acetonitrile, cyanamide, dicyanamide, acrylonitrile or polyacrylonitrile ≪ / RTI > The method according to claim 1,
Wherein the solvent comprises water, purified water, ethanol, or propyl alcohol. The method according to claim 1,
Wherein the lyophilizing step is performed at a temperature of -40 캜 to -30 캜. The method according to claim 1,
Wherein the temperature of the heat treatment step is 800 ° C to 900 ° C. The method according to claim 1,
Wherein the heat treatment is performed in an argon gas atmosphere. A catalyst prepared by the method of claim 1. A membrane-electrode assembly comprising a catalyst prepared by the method of claim 1. A membrane-electrode assembly comprising a catalyst prepared by the method of claim 1 and a platinum catalyst. 11. A fuel cell comprising the membrane-electrode assembly of claim 10 or claim 11. Peeling the stacked cup carbon nanofibers to form carbon powder;
Mixing the carbon powder and the solvent, followed by lyophilization to form a mixed powder; And
And heat treating the mixed powder,
Wherein the carbon powder comprises 0-dimensional graphene nanoflake and 1-dimensional graphene nanoribbons. 14. The method of claim 13,
The stacked cup-shaped carbon nanofibers have a stacked cup-shaped carbon and stacked cup-shaped carbon nanofibers surrounded by a few graphitic walls. Wherein the carbon nanofibers are formed on the substrate. 13. A carbon composite prepared by the method for producing a carbon composite material according to claim 13. An electrode structure comprising the carbon composite material according to claim 15.

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