KR101584170B1 - Three dimensional structured carbon supported catalyst using carbon nantotubes and method for preparing the same - Google Patents

Abstract

After partially dehydrohalogenating the polymer fibers, porous carbon nanotubes are prepared through heat treatment, and then the obtained carbon nanotubes are used to produce a non-noble metal catalyst or a non-metal catalyst. As a result, a non-noble metal and / or a non-metal catalyst for electrochemical reaction of pores having uniform porosity can be produced. The catalyst improves the mass transfer rate of the reactant in the electrochemical reaction electrode, thereby increasing the performance of the electrochemical reaction electrode.

Description

TECHNICAL FIELD [0001] The present invention relates to a three-dimensional carbon-supported catalyst using carbon nanotubes and a method for preparing the same,

The present invention relates to a method for producing a carbon-supported catalyst having a novel three-dimensional structure by preparing carbon nanotubes by dehydrohalogenating the polymer fibers to prepare porous carbon nanotubes, a carbon-supported non-noble metal catalyst for electrochemical reactions, / Or a non-metal catalyst.

There is a method of synthesizing a compound in which iron and nitrogen exist in the form of a ring and the like to use the catalyst as a catalyst for fuel cells (Patent Documents 1 to 3).

For example, Patent Document 1 is for producing an iron-cobalt hybrid catalyst using a carbon supporting material, and Patent Document 2 is for preparing a catalyst by heating and treating a mixture of a noble metal salt and carbon black, Document 3 is to prepare an electrode catalyst using a transition metal and chalcogen.

However, according to the studies of the present inventors, catalysts produced using these conventional methods have been found to form a thick catalyst layer on the cathode of a fuel cell, thereby increasing the mass transfer resistance, thereby rapidly raising the overvoltage of the fuel cell at high output current There are disadvantages. In order to solve such a problem, it is important to prepare a catalyst having a structure which is excellent in activity and can be well-developed in pores.

U.S. Patent Application Publication No. 2014-0024521 U.S. Patent Application Publication No. 2014-0045098 U.S. Patent No. 7,851,399

Embodiments of the present invention, in one aspect, provide a non-noble metal catalyst and / or a non-metal catalyst having high activity and stability, without using a noble metal, in place of conventional methods that are expensive to manufacture.

In embodiments of the present invention, in another aspect, porous carbon nanotubes having a well-developed pore structure obtained by de-halogenating and then carbonizing polymer fibers are used and the pore structure is well developed in the final catalyst A non-noble metal catalyst and / or a non-metal catalyst capable of enhancing the mass transfer rate of the reactant in the electrochemical reaction electrode, thereby increasing the performance of the electrochemical reaction electrode.

According to one embodiment of the present invention, there is provided a method for fabricating a polymer fiber, comprising: a first step of forming a polymer fiber using a halogenated polymer; A second step of preparing a carbon nanotube by partially dehydrogenating and heat-treating the polymer fiber; A third step of mixing the obtained carbon nanotube with a first compound and / or a second compound; And a fourth step of heat-treating the mixture, wherein the first compound includes a heterocyclic compound including a non-noble metal and a carbon compound, and the second compound includes a carbon compound including a non-metallic substance other than carbon A carbon-supported catalyst for electrochemical reaction.

According to one embodiment of the present invention, there is provided a carbon-supported catalyst for an electrochemical reaction produced by the above method, wherein a non-metallic substance other than carbon is present on the surface of the carbon nanotube and / or a non-noble metal, There is provided a carbon-supported catalyst for electrochemical reaction in which a three-dimensional pore structure including a non-metal and carbon is formed.

In exemplary embodiments, the carbon nanotubes preferably have a carbon structure therein.

According to embodiments of the present invention, in one aspect, the catalyst can be manufactured using noble metal and / or non-metal materials, which are low in price without using a noble metal, thereby greatly reducing the manufacturing cost of the catalyst.

Further, in another aspect, the noble metal and / or non-metal catalyst obtained by the production method using carbon nanotubes according to the embodiments of the present invention can be used as a catalyst of an electrochemical reaction electrode, The pore structure of the electrochemical reaction electrode has a well-developed pore structure formed by the three-dimensional pore structure, thereby improving the mass transfer rate of the reactant in the electrochemical reaction electrode, thereby increasing the performance of the electrochemical reaction electrode.

Therefore, the non-noble metal and / or the non-metal catalyst can be very usefully used for an electrochemical reaction such as a carbon dioxide conversion reaction or a fuel cell.

1 is a flow chart showing a procedure for manufacturing a catalyst for electrochemical reaction according to an exemplary embodiment of the present invention.
FIGS. 2A, 2B, and 2C are cross-sectional images of carbon nanotubes having a web structure in the form of a web in a scanning electron microscope in the embodiment of the present invention. 2D is an image of the carbon nanotube observed by a transmission electron microscope.
3A is an image obtained by observing a cross section of a carbon nanotube whose interior is hollowed by a scanning electron microscope in the embodiment of the present invention. 3B is an image observed at a high magnification.
4A and 4B are images showing a non-noble metal catalyst prepared by using only a heterocyclic compound and a carbon compound without using carbon nanotubes by a scanning electron microscope in the comparative example of the present invention. 4c and 4d are images of a porous non-noble metal catalyst prepared by mixing a carbon nanotube, a heterocyclic compound, and a carbon compound by a scanning electron microscope in an embodiment of the present invention.
5A is an image of a non-precious metal catalyst observed at a low magnification by a transmission electron microscope in the embodiment of the present invention. 5B is an image obtained by observing a columnar structure formed on the surface of a carbon nanotube by a transmission electron microscope at a high magnification in the embodiment of the present invention. FIG. 5C is an image obtained by observing a sheet-like carbon structure at a high magnification by a transmission electron microscope in an embodiment of the present invention.
6A is an image of a sheet-like structure formed on a noble metal catalyst in an embodiment of the present invention by a transmission electron microscope. FIG. 6B is a view of an orange square region in FIG. 6A observed by a high-angle scattering dark field scanning transmission electron microscope. 6C and 6D show the distribution of carbon, nitrogen, and iron elements observed with a fluorescent X-ray analyzer in FIG. 6B. FIG. 6F shows the carbon, nitrogen, and iron elements stacked in FIG. 6B.
FIG. 7 is a graph showing an image obtained by observing a carbon nanotube portion of a non-precious metal catalyst using a scanning transmission electron microscope and line profile analysis of an element on an orange line in an image with a fluorescent X-ray analyzer in an embodiment of the present invention.
FIG. 8 shows the results of analysis of crystallinity of carbon nanotubes and noble metal catalysts prepared therefrom by X-ray diffraction (XRD) in the examples of the present invention.
9A to 9C are results of analysis of elements existing on the surface of a noble metal catalyst by X-ray photoelectron spectroscopy in the embodiment of the present invention.
10 is a graph illustrating the results of evaluating the performance of oxygen reduction reaction of non-noble metal catalysts and commercial catalysts through experiments of semiconductors in the examples of the present invention. FIG. 10A is a result of 0.1 M potassium hydroxide solution, and FIG. 10B is a half cell test result of 0.5 M sulfuric acid solution.
11A is an image of a non-metal catalyst formed on a carbon nanotube observed by a scanning electron microscope in an embodiment of the present invention. 11B is an image of a non-metallic catalyst observed with a transmission electron microscope in an embodiment of the present invention.
12A is an image of a non-metal catalyst observed at a high magnification by a transmission electron microscope in an embodiment of the present invention. 12B is a graph showing the difference in light and darkness with respect to the white line in FIG. 12A.
13A is an image of a non-metal catalyst observed by a transmission electron microscope in an embodiment of the present invention. FIG. 13B is a view of the orange square region in FIG. 13A observed by a high-angle scattering dark-field scanning transmission electron microscope. 13C and 13D show the distribution of carbon, nitrogen and oxygen elements observed with a fluorescent X-ray analyzer in FIG. 13B. FIG. 13f shows the carbon, nitrogen, and oxygen elements stacked in FIG. 13b.
FIG. 14 is a graph showing the results of evaluating the performance of a non-metal catalyst and a commercial catalyst in an oxygen reduction reaction in a 0.1 M potassium hydroxide solution through an experiment of a half cell in an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail.

As used herein, a carbon compound means an organic or inorganic compound containing carbon. That is, it is a compound that can be a source of carbon including carbon. For reference, the carbon compound may or may not further include a non-metallic substance other than carbon.

In the present specification, a carbon compound including a non-metallic substance other than carbon means a compound formed by bonding a non-metallic substance such as hydrogen, oxygen, or nitrogen to carbon or carbon as a basic skeleton. For example, in the case of cyanide or hydrogen cyanide, it may be a carbon compound including a non-metallic substance other than carbon.

In the present specification, a three-dimensional pore-forming structure (or a three-dimensional structure) is a three-dimensional structure formed on the surface of a carbon nanotube (e.g., a stem-like or branched or network- Which form pores. Here, the three-dimensional structures form pores because the structures are connected to each other to form three-dimensional pores (e.g., macroscopic holes). Of course, the structure itself may also include pores (e.g., micropores, etc.). The three-dimensional pore-forming structure is mainly composed of carbon, and may further include other non-precious metals or non-metals.

In this specification, the term "heat treatment" means that the temperature is raised to the first temperature, the temperature is maintained at the corresponding temperature for a predetermined time, and then the temperature is raised to the second temperature and maintained for a predetermined time at the temperature. On the other hand, the heat treatment in one step means that the temperature is directly raised to the target temperature without performing the two steps, and then maintained for a predetermined time at the temperature.

In the exemplary embodiments of the present invention, a polymer fiber is formed using a halogenated polymer (step 1), a part of the polymer fiber is dehydrohalogenated and heat treated to produce carbon nanotubes (step 2) The obtained carbon nanotubes are mixed with the first compound and / or the second compound (third step), and the mixture is heat-treated (step 4). The first compound includes a heterocyclic compound including a non-noble metal and a carbon compound, and the second compound includes a carbon compound including a non-metallic material other than carbon. As a result, it is possible to produce carbon-supported non-noble metal and / or non-metal catalyst for electrochemical reaction of porous catalysts with well-developed pores. Described above.

In exemplary embodiments of the present invention, first, a polymer fiber is prepared using a halogenated polymer by, for example, electrospinning (first step). In an exemplary embodiment, a method for producing a polymer fiber using a halogenated polymer will be described as follows.

First, a halogenated polymer solution is prepared by mixing a halogenated polymer raw material with a solvent. The reason for producing the polymer fiber using the halogenated polymer is that the halogenated polymer is not de-halogenated through the dehalogenation process, and the remaining halogenated polymer is decomposed and removed in the subsequent carbonization process at a high temperature, hollow to form a carbon nanotube. Further, since the dehydrogenated halogenated polymer is decomposed to form a new structure, a carbon nanotube having a web structure in a cavity can be easily produced It can be used as a raw material.

As described above, the halogenated polymer can be used to form the polymer fiber by, for example, electrospinning, electroblown, meltblown, or the like. Electrospinning is suitable for producing nano-sized polymer fibers with small diameters.

Next, a part of the polymer of the polymer fiber is dehydrohalogenated and then heat-treated at a high temperature to decompose or vaporize the halogen polymer remaining in the polymer fiber, and carbon nanotubes can be produced by carbonizing the dehydrohalogenated polymer on the outer wall have. On the other hand, the polymer not subjected to the dehalogenation treatment in the dehalogenation process may remain in the polymer fiber, and may be decomposed or vaporized in the subsequent heat treatment process to form a cavity there.

Non-limiting examples of halogenated polymers include polyvinylidene fluoride, poly (vinylidene fluoride-co-hexafluoropropylene), poly (vinylidene fluoride-co-trifluoroethylene), perfluoropolymers A homopolymer or a copolymer of a chlorinated polymer monomer including a fluoropolymer homopolymer or copolymer, polyvinyl chloride, polyvinylidene chloride, poly (vinylidene chloride-co-vinyl chloride), and a saran polymer; May be used.

In an exemplary embodiment, it is preferable to control the dispersion and viscosity of the halogenated polymer solution.

That is, in the first step, it is preferable to prepare a halogenated polymer solution having a high degree of dispersion while maintaining a certain degree of viscosity of the halogenated polymer solution. This is because different types of carbon nanotubes can be manufactured in the final heat treatment process depending on the dispersion degree / viscosity of the halogenated polymer solution.

Particularly, when a halogenated polymer solution having a high degree of dispersion is used, a polymer fiber having a small diameter can be produced. As the polymer fibers having a small diameter and a uniform diameter are formed, a non-noble metal catalyst and / or a non-metal catalyst material having a well-developed pore structure can be manufactured. In a non-limiting example, the diameter of the polymer fibers is, for example, 20 to 1000 nm, and the range of the deviation of the diameter is 10 to 300 nm.

On the other hand, when the polymer fibers are dehydrohalogenated in a second step to be described later and subjected to heat treatment, carbon nanotubes are produced. In a non-limiting example, when a halogenated polymer solution having a high degree of dispersion is used, A carbon nanotube in which a structure (for example, a carbon structure in the form of a web) is present can be produced. It is more preferable to prepare a non-noble metal catalyst and / or a non-metal catalyst by using the carbon nanotubes in which the carbon structure is formed in view of the development of the pore structure.

Meanwhile, in an exemplary embodiment of the present invention, carbon nanotubes are prepared by dehydrohalogenating at least a part of the polymer fibers obtained through the first step, followed by heat treatment (second step).

Since the halogenated polymer melts at a relatively low temperature near 200 ° C and changes into a liquid phase, if carbonized through a high-temperature heat treatment in a heating furnace, it may be vaporized or decomposed to lose the shape of the fiber. Therefore, in the second step according to the exemplary embodiment of the present invention, at least a part of the polymer fibers is dehydrohalogenated before carbonization of the polymer fibers.

In a non-limiting example, for dehalogenation, the halogenated polymeric fibers are treated with a strong alkaline aqueous solution or a strongly alkaline organic solution. Whereby the chemical dehalogenation reaction in which the halogen element is removed can be induced.

Thereafter, the carbon nanotubes can be produced by carbonizing the dehydrogenated polymer fibers by heat treatment at a high temperature in a heating furnace.

The heat treatment may be performed in a mixed gas containing, for example, at least one of nitrogen, argon, helium, hydrogen, etc., or a temperature range of 100 to 2000 占 폚 under a vacuum atmosphere. Through such a heat treatment process, the dehydrohalogenated polymer fibers can be carbonized accompanied by a carbonization (graphitization) reaction.

Meanwhile, in an exemplary embodiment of the present invention, a non-noble metal catalyst and / or a non-metal catalyst can be prepared using the obtained carbon nanotubes.

In one embodiment, the method for preparing a non-noble metal catalyst comprises mixing the first compound and the carbon nanotubes (step 3), and heat-treating the mixture (step 4).

Specifically, for example, a first compound, that is, a heterocyclic compound containing a non-noble metal, and a carbon compound are mixed and stirred in a solvent, and the obtained carbon nanotube is mixed with the solution and stirred. Then, after the mixture is prepared, a non-noble metal catalyst supported on the porous carbon nanotube and the porous three-dimensional pore structure (carbon body) can be produced through heat treatment at a high temperature. As a result, a porous non-noble metal catalyst having well-developed pore structure can be produced.

A process for preparing a mixed solution by mixing a heterocyclic compound containing a non-noble metal and a carbon compound in a solvent (third step) is described below as a non-limiting example.

First, a heterocyclic compound containing a noble metal and a carbon compound are mixed in a solvent, and the two compounds are sufficiently mixed in a solvent for 1 to 50 hours, for example, by stirring using an ultrasonic wave or a magnetic stirrer.

The reason why the heterocyclic compound containing a noble metal is added to the mixed solution is that the heterocyclic compound containing such a noble metal can act as a catalyst for the electrochemical oxygen reduction reaction. Also, in the heat treatment process, the non-noble metal heterocyclic compounds contained in the mixture are bonded to each other to change into metal particles, and these metal particles are converted into three-dimensional structures (for example, structures having a stem or branch shape or a network structure) The three-dimensional structure can form pores (mainly macropores) by being connected with other structures in the surrounding, and thus can form a noble metal catalyst having a well-developed pore structure have.

The heterocyclic compound containing the non-noble metal may contain nitrogen, oxygen, sulfur, silicon, boron, phosphorus, etc. in addition to carbon, and may have a three-dimensional structure in which rings and rings are overlapped with each other. Or an aromatic compound which forms an atomic bond of a covalent double bond ring.

As the non-limiting examples of the heterocyclic compound including the above-mentioned noble metal, a heterocyclic compound including a transition metal such as Fe, Co, Cu, Ni, Zn, and Mg can be used.

More specifically, in a non-limiting example, a heterocyclic compound comprising a transition metal of a non-noble metal may comprise a phthalocyanine or a naphthalocyanine. For example, the heterocyclic compounds containing non-noble metals are iron (II) phthalocyanine, iron (III) phthalocyanine chloride, iron (III) phthalocyanine-4,4 ' monosodium salt hydrate, Cobalt (II) phthalocyanine, Cobalt (II) 2,3-naphthalocyanine, Copper (II) phthalocyanine, Copper (II) 1,4,8,11,15,18,22,25-octabutoxy- 31H-phthalocyanine, Nickel (II) phthalocyanine, Zinc phthalocyanine, Zinc 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro- (III) phthalocyanine chloride, Silver (III) -phthalocyanine, Mg phthalocyanine, Mg tetracarboxylic phthalocyanine, Ge (IV) phthalocyanine, Silicon phthalocyanine dichloride, Tin (II) phthalocyanine, Aluminum phthalocyanine hydroxide, Disodium phthalocyanine, Gallium phthalocyanine, and Vanadyl 2,3-naphthalocyanine. These compounds may be used singly or in combination of two or more thereof.

On the other hand, the carbon compound is mixed with the heterocyclic compound including the above-mentioned noble metal. When the non-noble metal particles generated in the heat treatment form a structure (three-dimensional pore structure) around the carbon body, The compound can be a carbon source for forming such a structure (three-dimensional pore-forming structure). Further, when the carbon compound further includes a non-metallic material other than carbon, it can act as a source of carbon and non-metallic materials or as a catalyst for growth of the pore-forming structure. According to this method, for example, a three-dimensional pore-forming structure in the shape of a stem, a branch or a network can be grown without injecting an external carbon and / or nonmetallic material source.

The carbon compound is not particularly limited as long as it is a carbon source. In addition, for example, carbon may be a compound having a basic skeleton and formed by combining not only hydrogen but also nonmetal materials such as oxygen, nitrogen, sulfur, phosphorus, boron, sulfur and halogen elements. The bond may be composed of a single bond, a double bond, a triple bond, or the like.

As a non-limiting example of the carbon compound, cyanide, cyanates, cyanogen, or other organic nitrogen compounds may be used alone or in combination.

Specifically, the carbon compound is selected from the group consisting of N, N'-Dimethylethylenediamine, Cyanide, Lithium cyanide, Chloroacetonitrile, Cyanomethanesulfonyl chloride, Cyanamide, Diethylcyanamide, Fumaronitrile, Acetylmalononitrile, cis-Mucononitrile, 2-Amino-1,1,3-propenetricarbonitrile, And may be at least one selected from the group consisting of -Hexenedinitrile, Cyanogen, Cyanogen bromide, Propiolamide, 2-Bromo-2-fluoroacetamide, 3-amino-propionitrile and Diethyl phosphoramidate.

The three-dimensional pore structure is formed on the surface of the carbon nanotubes to be mixed in the mixed solution. The direction in which the three-dimensional pore structure is grown is determined by the directionality of the carbon nanotubes, Can have a well-developed structure.

The three-dimensional pore-forming structure is mainly composed of carbon, and includes synthesized noble metal particles, and may further include a base metal. (O), nitrogen (N), boron (B), sulfur (S), phosphorus (P) or the like derived from a heterocyclic compound or a carbon compound (when the carbon compound further contains a non- , Fluorine (F), iodine (I), and chlorine (Cl) may exist in the form of a porphine or a compound.

These three-dimensional pore-forming structures have catalytic activity.

In a non-limiting example, the size of the synthesized non-precious metal particles may be between 1 nm and 100 nm. For reference, in the case where carbon nanotubes are not used as in the embodiments of the present invention, the size of the metal particles may be 100 nm or more since heat treatment is performed in a state in which the heterocyclic compound is not easily dispersed, Can be lowered.

Next, the prepared mixed solution is dried and then heat-treated at a high temperature to prepare a porous noble metal catalyst (Step 4).

The heat treatment may be performed at a temperature ranging from 100 to 2000 ° C under a vacuum or a mixed gas containing, for example, nitrogen, argon, helium, hydrogen, or the like. Through such a heat treatment process, the heterocyclic compound including the noble metal and the carbon compound are bonded to each other at the surface of or around the carbon nanotube and carbonized, and a new structure, that is, a carbon nanotube having a three- To form a noble metal catalyst. In a non-limiting example, as noted above, in the three-dimensional pore-forming structure, non-precious metals may be present evenly distributed with carbon and nonmetals.

If the temperature is less than 100 ° C, the above reaction may not occur. If the temperature exceeds 2000 ° C, most of non-metallic substances such as carbon and nitrogen may be burned and disappear. The specific heat treatment temperature within the above-mentioned temperature range can be controlled in consideration of the type of pores to be formed and the activity of the catalyst. Generally, if the heat treatment temperature is too low, the pore structure will not be formed, whereas if it is too high, the formed pore structure will be decomposed and the catalyst activity will decrease. In this respect, a preferable temperature range is 600 to 1000 占 폚.

Meanwhile, in another exemplary embodiment of the present invention, the method for producing a non-metal catalyst comprises mixing the second compound and the carbon nanotubes (step 3), and heat-treating the mixture (step 4).

Specifically, for example, a carbon compound containing a second compound, i.e., a non-metal catalytic active substance other than carbon, and the carbon nanotube obtained above are mixed and stirred in a solvent (third step), and the resulting mixture is dried, A porous non-metal catalyst can be prepared (Step 4). Accordingly, a non-metal catalyst (i.e., a carbon-supported nonmetal catalyst) having a structure in which a non-metallic material other than carbon is covered on the surface of the porous carbon nanotube can be produced.

In a non-limiting example, the non-metallic material comprises at least one of nitrogen (N), boron (B), sulfur (S), phosphorus (P), fluorine (F), iodine ). ≪ / RTI >

The heat treatment may be performed at a temperature of 100 to 2000 ° C under a mixed gas or a mixed gas containing, for example, nitrogen, argon, helium, hydrogen, or the like.

In addition, the heat treatment process may be carried out by using hydrogen containing compounds such as carbon or nitrogen, for example, methane (CH ₄ ), ethane (C ₂ H ₆ ), acetylene (C ₂ H ₂ ), propane (C ₃ H ₈ ) a C ₃ H _6), butane (C ₄ H _10), hexane (C ₅ H _10), heptane (C ₆ H _14), ammonia (NH ₃₎ adding a gas or a mixture gas containing steam is at least one, such as (Carbonization reactor). ≪ / RTI > These gases are either carbon sources or nitrogen (non-metallic materials other than carbon) sources. Of course, in the case of the embodiments of the present invention, there is no need to inject the corresponding gases, but it is also possible to inject additional gases.

In an exemplary embodiment, the heat treatment during the production of the non-metal catalyst is divided into two stages. The first stage is preferably carried out at 100-600 ° C, and the second stage is preferably carried out at 600-2000 ° C.

The reason for performing the heat treatment in two steps is to primarily remove the solvent and also to form a bond between the carbon compounds. This bond between the carbon compounds proceeds at a slow rate for a long time. When the heat treatment is performed at a high temperature immediately without such a step, the carbon compounds are evaporated or decomposed at a high temperature and may be discharged to the outside of the reactor in a gaseous state because the bonding between the carbon compounds is not sufficiently performed.

In the exemplary embodiments of the present invention, since the bonding of the carbon compounds formed on the surface of the carbon nanotube serves as an active point of the catalyst, it is advantageous to prepare the non-metal catalyst by dividing the heat treatment step into two stages .

Meanwhile, in another exemplary embodiment of the present invention, the heterocyclic compound including a noble metal may be mixed together in the production of the non-metal catalyst. [In this case, the heterocyclic compound including a noble metal, the carbon compound (non- Is mixed with the carbon nanotubes]. In this case, since there is a heterocyclic compound including a noble metal, heat treatment can be performed in one step without performing two steps.

Hereinafter, the present invention will be described in more detail by way of non-limiting and illustrative examples.

[Example 1]

Step 1

1.5 g of polyvinylidene fluoride as a halogenated polymer was mixed with 7.5 g of acetone and 2.5 g of dimethylacetamide, followed by stirring for about 5 minutes.

Then, 2.5 μl of 1,8-diazabicyclo [5,4,0] undec-7-ene (DBU) was added to the reaction mixture and stirred at about 70 ° C. for 30 minutes.

The polymer solution thus prepared was stirred again at 40 DEG C for 2 hours or 8 hours. The reason why the agitation time is different is that carbon nanotubes having different diameters and internal shapes are manufactured.

The polymer solution thus prepared was made into polymer fibers by electrospinning. The polymer fibers prepared from the polymer solution with stirring for 8 hours were small in diameter and uniform, and the polymer fibers prepared from the polymer solution stirred for 2 hours had large diameters and nonuniformities.

As the electrospinning condition, the discharge rate of the polymer solution was set to about 30 μl / min, and the potential difference between the needle of the solution inserting needle and the bottom surface where the injected polymer fibers fell was about 18 kV to 20 kV.

Step 2

The dehydrohalogenation treatment of the polymer fibers prepared in the first step was performed.

A strong alkaline aqueous solution was used for the dehalogenation treatment. The specific dehalogenation treatment conditions were as follows.

Namely, 80 g of natrium hydroxide was added to 418 g of distilled water and 2 g of tetra-n-butylammonium bromide (TBAB) as a phase transfer catalyst was added thereto, followed by stirring for about 20 minutes. At this time, the temperature of the solution was heated to 70 占 폚, the temperature of the solution became 70 占 폚, and the electrospun polymer fibers were added and stirred for 10 minutes.

Thereafter, heat treatment was performed in a nitrogen atmosphere using a heating furnace. The heating rate of the heating furnace was 10 ° C / min. After heating from room temperature to 800 ° C, it was maintained at the temperature for 1 hour.

FIGS. 2A, 2B, and 2C are SEM images of the carbon nanotubes produced in an embodiment of the present invention. FIG. Referring to FIGS. 2A, 2B, and 2C, the carbon nanotubes prepared by stirring the polymer solution at 40 ° C for 8 hours have a small diameter (less than 300 nm), uniformity, and a carbon-like carbon structure inside the tube. FIG. 2 (d) shows a transmission electron microscope image of the carbon nanotube thus prepared. It can be observed that the carbon structures in the carbon nanotubes exist in the form of a spider web.

3A and 3B are SEM images of carbon nanotubes prepared by stirring the polymer solution at 40 DEG C for 2 hours. These carbon nanotubes are large in diameter, non-uniform, and have no carbon structure inside. The polymer fibers prepared by electrospinning after stirring for 2 hours are larger in diameter than the polymer fibers produced by stirring for 8 hours and are uneven. Dehalogenation of polymer fibers progresses rapidly on the surface, and gradually becomes slower toward the inside of the fibers.

More specifically, as the diameter of the polymer fiber becomes larger, dehalogenation occurs mainly on the surface of the fiber, and the inside of the fiber is not dehalogenated. The halogen polymer in the fiber is decomposed or vaporized without being carbonized while being subjected to a heat treatment at a high temperature, and is discharged to the outside of the reactor, thereby forming a hollow in the fiber. On the other hand, the polymer fibers of the dehalogenated portion are carbonized to form carbon hollow fibers, that is, carbon nanotubes having cavities therein.

Polymer fibers prepared by electrospinning after stirring for 8 hours are small in diameter and uniform. If the diameter of the polymer fiber is small, dehalogenation progresses partly as well as on the surface of the fiber. The partially de-halogenated polymer inside the polymer fiber may form carbon nanotubes through the high-temperature process of heat treatment and may additionally form a carbon fiber structure in the carbon nanotubes.

Carbon nanotubes produced by this method have characteristics that the fine (less than 2 nm) and / or mesopores (between 2 nm and 50 nm) are well developed, while having a wide specific surface area of 1358 m ² / g. Macro pores of 50 nm or more can also be included. When the carbon nanotubes are used, a catalyst for non-noble metal and / or non-metal electrochemical reaction having high catalytic activity can be produced.

Step 3

0.8 g of cyanamide and 0.2 g of iron phthalocyanine (Iron (II) phthalocyanine) were mixed in an ethanol solution, and the mixture was stirred for about 1 hour.

0.2 g of the finely ground powdered carbon nanotubes (both of which was stirred for 2 hours and stirred for 8 hours) were added to the iron phthalocyanine mixture and stirred at 60 ° C for 12 hours or more.

Step 4

The mixture prepared in the third step was dried in an oven at 50 DEG C for 24 hours or more, put into a heating furnace, and carbonized in a nitrogen atmosphere.

The heating rate of the furnace was heated from room temperature to 800 ° C at a rate of 20 ° C / min, and then maintained at that temperature for 1 hour.

4 is a scanning electron microscope image of a catalyst for noble metal / nonmetal electrochemical reaction produced in Examples and Comparative Examples of the present invention. 4A and 4B are non-noble metal catalysts prepared by carbonizing carbon phthalocyanine mixtures without carbon nanotubes (Comparative Example: the rest of the procedure is the same except that carbon nanotubes are not added). 4c and 4d, carbon nanotubes were placed in an iron phthalocyanine mixture and carbonized (Example).

Referring to FIG. 4, in a non-noble metal catalyst (FIGS. 4c and 4d) prepared by mixing a carbon nanotube and an iron-phthalocyanine mixture, a three-dimensional structure web- To 1 mm) can be observed. This structure facilitates the mass transfer of the reactants and products of the electrochemical reaction, thereby increasing the performance of the electrochemical reaction. In addition, the above structure is evenly distributed over a large area of the carbon nanotubes. Therefore, the above catalyst has a relatively large specific surface area (463 m ² / g). On the other hand, it is difficult to observe the three-dimensional structures and pores of the catalysts prepared without adding carbon nanotubes (FIGS. 4A and 4B). The specific surface area of the catalyst prepared by carbonization without carbon nanotubes is about 208 m ² / g, which is relatively small.

For reference, as described above, the above-described three-dimensional structure can be said to be produced by bonding cyanamide and iron-phthalocyanine to each other at a temperature of 600 ° C or higher, for example.

5 is an image of a transmission electron microscope of a noble metal catalyst prepared by mixing carbon nanotubes in an embodiment of the present invention.

Referring to FIG. 5A, it can be seen that three-dimensional structures are formed around the carbon nanotubes. The structure can be broadly classified into a branch form and a sheet form.

FIG. 5B shows an image of a structure of a type observed by a transmission electron microscope. Iron particles are present in this structure. Iron particles are formed while iron-phthalocyanine bonds. Cyanamide is present around the iron particles. This cyanamide acts as a carbon and nitrogen source to form a three-dimensional structure. Therefore, a three-dimensional structure (mainly a carbon structure made of carbon) grows around the iron particles, wherein the growth direction of the structure is affected by the carbon nanotubes. Depending on the orientation of the carbon nanotubes, the direction in which the structure grows is determined. These structures are grown in a three-dimensional form due to the structural orientation of the carbon nanotubes, for example, when the carbon nanotubes are bonded from the surface or inside of the carbon nanotubes at a temperature of 600 ° C or higher.

5C shows a sheet structure around carbon nanotubes observed with a transmission electron microscope. Figure 5c shows lattice structures formed by bonding of carbons. These three-dimensional structures are composed of carbon, iron, nitrogen and oxygen atoms.

FIG. 6 is a result of analysis of elements of a three-dimensional structure through an energy dispersive X-ray analysis (EDX) in a scanning transmission electron microscope (STEM) according to an embodiment of the present invention . 6A is a view of a three-dimensional structure in the form of a sheet with a scanning transmission electron microscope. FIG. 6B is a detailed view of the atomic structure of the orange square region in FIG. 6A by refining the electron beam to about 1 angstrom with a high angle annular dark field (HAADF). As a result of observation, it can be observed that the structure overlaps several layers in a sheet form. 6C and 6D show the distribution of carbon, nitrogen, and iron elements observed with a fluorescent X-ray analyzer in FIG. 6B. FIG. 6F shows the carbon, nitrogen, and iron elements stacked in FIG. 6B.

The three-dimensional structures formed around the carbon nanotubes may be in the form of iron-porphyrin-like materials composed of nitrogen-oxygen-carbon material, or iron-nitrogen-carbon, produced by bonding nitrogen and oxygen with carbon structures . Iron-porphyrin has a structure in which an iron atom is bonded to nitrogen in the form of a ring structure. This bonding structure allows the iron atom to be present as a ferrous ion (Fe ^{2 +} ). The site of the ferrous ion acts as a place where it can easily bind to water. The binding energy of water and ferrous ion sites has a relatively low value (0.10 eV). Then, the water bound to the primary iron ion site can be easily replaced with oxygen, and this process serves as a principle in which the iron-porphyrin structure contributes to the oxygen reduction reaction.

FIG. 7 is a graph showing an image (FIG. 7A) of a surface of a carbon nano tube of a noble metal catalyst by a scanning electron microscope in an embodiment of the present invention and an image (FIG. (Fig. 7B and 7C). It can be observed that iron particles (bright areas) exist on the surface of the carbon nanotubes. These iron particles play a role in forming a three-dimensional structure of a branch from the surface of carbon nanotubes. Among the elements observed in the orange line region, carbon, nitrogen and iron were observed. As a result, it can be seen that materials composed of iron-nitrogen-carbon are uniformly distributed on the surface of the carbon nanotubes.

Figs. 7B and 7C are line profile results, and 7C is an enlarged view of 7b, showing the presence of elements distributed on the oblique line (orange line; carbon nanotube surface) of Fig. 7A. It can be seen that most of the carbon is present and nitrogen and iron are present, and nitrogen and iron particles are evenly distributed on the surface of the carbon nanotubes. Particularly, iron particles are distributed evenly with carbon and nitrogen as well as light colored portions (large iron particles) as well as particles of very small size.

8 shows the results of analyzing the crystal structure of carbon nanotube (CNT) and non-noble metal catalyst (Fe-N-CNT) by X-ray diffraction (XRD) in the embodiment of the present invention. Carbon nanotubes have an amorphous structure, while non-noble metal catalysts have a crystalline structure. As a result of the analysis of the noble metal catalyst, it can be confirmed that there is crystalline carbon and iron, and through this, cyanamide and iron-phthalocyanine are bonded in a high-temperature heat treatment process to form a crystalline catalyst material around the carbon nanotubes .

FIG. 9 is a graph showing the results of analysis of elements on the surface of a noble metal catalyst by X-ray photoelectron spectroscopy (XPS) in the embodiment of the present invention. FIG. 9A shows a spectrum according to the bonding form of carbon. FIG. Most of the carbon exists in the form of bonded carbon bonds, but it can be confirmed that carbon exists in the form of bonding with oxygen or nitrogen. FIG. 9B shows a spectrum according to the bonding form of nitrogen. There are predominantly pyridinic and pyrolic forms of nitrogen, with an atomic percentage of 7.7%. FIG. 9C shows a spectrum according to the bonding form of iron. It can be confirmed that iron exists in the form of ferrous ion (Fe ^{2 +} ) and ferric ion (Fe ^{3 +} ).

10 shows the results of a half-cell experiment using a rotating disc electrode (hereinafter referred to as RDE) of a non-noble metal catalyst (Fe-N-CNT) prepared in an embodiment of the present invention.

Half-cell experiments are conducted by applying a glassy carbon (glassy carbon) on the surface of 1mg / cm ² non-noble metal catalyst or a Pt / C catalyst commercially available of ^{0.01mg / cm 2 (40 wt.} % E-TEK) in the area of 0.196cm ² Respectively.

10A is a graph showing the results of measuring the performance of a catalyst for an oxygen reduction reaction in a 0.1 M potassium hydroxide (KOH) alkali electrolyte solution. The voltage scan rate was set at 5 mV / sec, and the rotational speed of the RDE half cell was set at 1600 rpm. As a result of the experiment, it can be confirmed that the non-noble metal catalyst (blue line) has superior performance to the oxygen reduction reaction than the commercial Pt / C catalyst (black line).

FIG. 10B shows the results of measurement of catalyst performance for an oxygen reduction reaction in a 0.5 M sulfuric acid (H ₂ SO ₄ ) solution. Experimental results show that the non-noble metal catalyst has a lower onset potential for the oxygen reduction reaction than the commercial Pt / C catalyst but has a relatively higher half potential and limiting current .

[Example 2]

The first and second steps were carried out in the same manner as in Example 1.

Step 3

0.8 g of cyanamide and 0.2 g of finely ground carbon nanotubes (both of which were agitated for 2 hours and agitated for 8 hours) were mixed in an ethanol solution and mixed for about 1 hour Lt; / RTI > Thereafter, the mixture was further stirred at 60 DEG C for 12 hours or longer.

Step 4

The mixture prepared in the third step was dried in an oven at 50 DEG C for 24 hours or more, put into a heating furnace, and carbonized in a nitrogen atmosphere.

The heat treatment in the furnace was carried out in two stages. That is, the temperature was raised from room temperature to 550 ° C at a heating rate of 3 ° C / min, maintained at this temperature for 4 hours, immediately increased to 900 ° C, and then maintained for 1 hour.

11 is an image of a scanning electron microscope and a transmission electron microscope of a nonmetal catalyst prepared in an embodiment of the present invention. 11A is an image of a non-metallic catalyst observed with a scanning electron microscope. 11B is an image of a nonmetal catalyst observed with a transmission electron microscope. FIG. 11B shows that the carbon structure is present in the catalyst.

12A is an image obtained by observing a non-metal catalyst at a high magnification by a transmission electron microscope in an embodiment of the present invention. Referring to FIG. 12A, it can be seen that the non-metal catalyst has an amorphous phase. However, the carbon nanotube surface portion of the non-metal catalyst is surrounded by the nitrogen-carbon structures of the crystal structure. 12B shows a contrast line profile based on the white line in FIG. 12A. It can be seen that the difference in contrast is repeated at regular intervals by the lattice of the nitrogen-carbon structure formed on the surface of the carbon nanotube. That is, it can be confirmed that it has a crystalline phase. The measured distance between the gratings is 0.33 nm.

13 is a result of analyzing elements of a non-metal catalyst with a fluorescent X-ray analyzer of a scanning transmission electron microscope in an embodiment of the present invention. 13A is an image of a non-metal catalyst observed with a scanning transmission electron microscope. 13B is a detailed view of the atomic structure of the orange square region in FIG. 13A by subdividing the electron beam to about 1 ANGSTROM using a high-angle scattering dark field night scanning transmission electron microscope. 13C and 13D and 13E show the distribution of carbon, nitrogen, and oxygen elements observed with the fluorescent X-ray analyzer in FIG. 13B. FIG. 13f shows the carbon, nitrogen, and oxygen elements stacked in FIG. 13b.

FIG. 14 shows experimental results of a half-cell of a non-metal catalyst (N-CNT) produced in an embodiment of the present invention. Half-cell tests were conducted by coating a glassy carbon (glassy carbon) of 1mg / cm ² on the surface of the base metal catalyst and 0.01mg / cm ² Pt / C catalyst commercially available (40 wt.% E-TEK ) in the area of 0.196cm ² . The voltage scan rate was set to 5 mV / sec, and the rotational speed of the half-cell was set to 1600 rpm.

14, it can be seen that the performance of the non-metal catalyst (red line) is lower than that of the commercial Pt / C catalyst (black line) in the potassium hydroxide (KOH) alkaline electrolyte solution of 0.1 M concentration . However, the performance difference is not large, and it is expected that when the amount of the non-metal catalyst is increased, the performance is higher than that of the commercial Pt / C catalyst.

Claims (24)

A first step of forming a polymer fiber by using a halogenated polymer;
A second step of preparing a carbon nanotube by partially dehydrogenating and heat-treating the polymer fiber;
The obtained carbon nanotubes; A third step of providing a mixture comprising at least one of the first compound and the second compound; And
And a fourth step of heat-treating the mixture,
The first compound includes a heterocyclic compound including a non-noble metal and a carbon compound,
The second compound includes a carbon compound including a non-metallic substance other than carbon,
Wherein the carbon nanotubes of the carbon-supported catalyst have a three-dimensional pore-forming structure on the surface thereof.
delete The method according to claim 1,
Wherein the three-dimensional pore-forming structure comprises carbon and a non-noble metal.
The method of claim 3,
Wherein the three-dimensional pore-forming structure further comprises a non-metal other than carbon.
The method according to claim 1,
Wherein the carbon compound of the first compound is a carbon source for forming the three-dimensional pore structure.
6. The method of claim 5,
The carbon compound of the first compound further comprises a non-metal other than carbon, and the carbon for forming the three-dimensional pore-forming structure; And a carbon and non-metal materials source of a non-metallic material other than carbon.
The method according to claim 1,
The non-noble metal of the heterocyclic compound including the noble metal includes iron (Fe), cobalt (Co), silver (Ag), aluminum (Al), copper (Cu), nickel (Ni) ), Indium (In), sodium (Na), lithium (Li), magnesium (Mg), manganese (Mn), silicon (Si), vanadium (V), tin (Sn), germanium (Ge) And tellurium (Te). ≪ RTI ID = 0.0 > 11. < / RTI >
8. The method of claim 7,
The heterocyclic compound may be a group consisting of oxygen (O), nitrogen (N), boron (B), sulfur (S), phosphorus (P), fluorine (F), iodine Wherein the carbon-containing catalyst comprises at least one selected from the group consisting of carbon,
9. The method of claim 8,
Wherein the heterocyclic compound comprises phthalocyanine or naphthalocyanine.
10. The method of claim 9,
(II) phthalocyanine, Copper (II) phthalocyanine, Cobalt (II) phthalocyanine, Cobalt (II) 2,3-naphthalocyanine, Copper 4,8,11,15,18,22,25-octabutoxy-29H, 31H-phthalocyanine, Nickel (II) phthalocyanine, Zinc phthalocyanine, Zinc 1,2,3,4,8,9,10,11,15, (II) phthalocyanine, Ge (IV) phthalocyanine, Silicon phthalocyanine dichloride, Tin (II) phthalocyanine, Aluminum phthalocyanine hydroxide, Disodium phthalocyanine , Gallium (III) -phthalocyanine chloride, Indium (III) phthalocyanine chloride, Silver phthalocyanine and Vanadyl 2,3-naphthalocyanine.
The method according to claim 1,
And the size of the noble metal particles obtained after the fourth step is 1 nm to 100 nm.
A first step of forming a polymer fiber by using a halogenated polymer;
A second step of preparing a carbon nanotube by partially dehydrogenating and heat-treating the polymer fiber;
The obtained carbon nanotubes; A third step of providing a mixture comprising at least one of the first compound and the second compound; And
And a fourth step of heat-treating the mixture,
The first compound includes a heterocyclic compound including a non-noble metal and a carbon compound,
The second compound includes a carbon compound including a non-metallic substance other than carbon,
Wherein the carbon nanotubes of the carbon-supported catalyst have a non-metallic substance bonded to the surface thereof.
A first step of forming a polymer fiber by using a halogenated polymer;
A second step of preparing a carbon nanotube by partially dehydrogenating and heat-treating the polymer fiber;
The obtained carbon nanotubes; A third step of providing a mixture comprising at least one of the first compound and the second compound; And
And a fourth step of heat-treating the mixture,
The first compound includes a heterocyclic compound including a non-noble metal and a carbon compound,
The second compound includes a carbon compound including a non-metallic substance other than carbon,
The carbon compound including the non-metallic substance other than carbon of the second compound is at least one selected from the group consisting of oxygen (O), nitrogen (N), sulfur (S), phosphorus (P) By weight based on the weight of the carbon supported catalyst.
14. The method of claim 13,
Wherein the carbon compound including the non-metallic substance other than carbon comprises nitrogen.
15. The method of claim 14,
The carbon compound including the non-metallic substance other than carbon may be selected from the group consisting of N, N'-Dimethylethylenediamine, Cyanide, Lithium cyanide, Chloroacetonitrile, Cyanomethanesulfonyl chloride, Cyanamide, Diethylcyanamide, Fumaronitrile, Acetylmalononitrile, wherein the catalyst is at least one selected from the group consisting of propenetricarbonitrile, trans-3-hexenedinitrile, cyanogen, cyanogen bromide, propiolamide, 2-bromo-2-fluoroacetamide, 3-amino-propionitrile and diethyl phosphoramidate.
The method according to claim 1,
Wherein the heat treatment temperature in the fourth step is 100 占 폚 to 2000 占 폚.
The method according to claim 1,
In the third step, the carbon nanotubes and the first compound are mixed,
Wherein the mixture prepared in the fourth step is dried and then heat-treated in one step.
A first step of forming a polymer fiber by using a halogenated polymer;
A second step of preparing a carbon nanotube by partially dehydrogenating and heat-treating the polymer fiber;
The obtained carbon nanotubes; A third step of providing a mixture comprising at least one of the first compound and the second compound; And
And a fourth step of heat-treating the mixture,
The first compound includes a heterocyclic compound including a non-noble metal and a carbon compound,
The second compound includes a carbon compound including a non-metallic substance other than carbon,
In the third step, the carbon nanotubes and the second compound are mixed,
The method for producing a carbon-supported catalyst according to claim 1, wherein the mixture prepared in the fourth step is dried and then heat-treated in two steps.
19. The method of claim 18,
Wherein the first heat treatment step is performed in the range of 100-600 占 폚, and the second heat treatment step is performed in the range of 600-2000 占 폚.
The method according to claim 1,
Wherein the carbon nanotube obtained in the second step has a carbon structure inside the tube.
A first step of forming a polymer fiber by using a halogenated polymer;
A second step of preparing a carbon nanotube by partially dehydrogenating and heat-treating the polymer fiber;
The obtained carbon nanotubes; A third step of providing a mixture comprising at least one of the first compound and the second compound; And
And a fourth step of heat-treating the mixture,
The first compound includes a heterocyclic compound including a non-noble metal and a carbon compound,
The second compound includes a carbon compound including a non-metallic substance other than carbon,
Wherein the carbon nanotubes obtained in the second step have at least one of micropores of less than 2 nm, mesopores of 2 nm to 50 nm, and macropores of 50 nm or more.
As a catalyst for an electrochemical reaction,
A non-metallic substance is bonded to the surface of the carbon nanotube;
A three-dimensional pore-forming structure is formed on the surface of the carbon nanotube; or
A carbon-supported catalyst characterized in that a non-metallic material is bonded to a surface of a carbon nanotube and a three-dimensional pore-forming structure is formed.
23. The method of claim 22,
Wherein the carbon nanotube has a carbon structure inside the tube.
23. The method of claim 22,
Wherein the carbon-supported catalyst has at least one selected from the group consisting of micropores of less than 2 nm, mesopores of 2 nm to 50 nm, and macropores of 50 nm or more,
The carbon nanotube has at least one selected from the group consisting of micropores of less than 2 nm, mesopores of 2 nm to 50 nm, and macropores of 50 nm or more,
Wherein the three-dimensional pore-forming structure formed on the surface of the carbon nanotube comprises macropores of 50 nm or more.

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