WO2013162097A1

WO2013162097A1 - Carbon nano-material, and preparation method thereof

Info

Publication number: WO2013162097A1
Application number: PCT/KR2012/003204
Authority: WO
Inventors: 정두환; 김상경; 임성엽; 백동현; 이병록; 김지영
Original assignee: 한국에너지기술연구원
Priority date: 2012-04-26
Filing date: 2012-04-26
Publication date: 2013-10-31

Abstract

The present invention relates to a carbon nano-material, and a preparation method thereof. The carbon nano-material of the present invention comprises a carbon nanofiber containing nitrogen. The method for preparing the carbon nano-material of the present invention comprises the steps of: introducing nitrogen gas into a reactor in the presence of a metal catalyst supported in a support; increasing temperature while supplying a gas mixture of nitrogen gas and hydrogen gas into the reactor; and supplying a nitrogen-containing compound into the reactor. According to the present invention, the carbon nano-material has remarkable durability and can more effectively support a catalyst, and thus performs excellently as a catalyst support. The carbon nano-material of the present invention shows remarkable durability due to excellent crystallinity by introducing nitrogen into a carbon nanofiber, more effectively supports a catalyst, and can improve dispersibility. The carbon nano-material of the present invention is expected to be used as a support of a catalyst including an electrode catalyst of a fuel cell and to be applied to develop a material of various fields.

Description

【Specification】

[Name of invention]

Carbon Nano Materials and Methods for Making the Same

Technical Field

The present invention relates to a carbon nanomaterial and a method for manufacturing the same, and more particularly, to a carbon nanomaterial and a method for producing the same, which are excellent in durability and capable of supporting a catalyst more efficiently.

Background Art

The fuel cell is a power generation system that directly converts the chemical reaction energy of hydrogen and oxygen contained in a hydrocarbon-based material such as methanol, ethane, and natural gas into electrical energy.

<3> Such a fuel cell is a clean energy source that can replace fossil energy, and has a merit that can produce a wide range of outputs by stacking a unit cell stack. It is attracting attention as a compact and mobile portable power source because it shows 10 times the energy density.

<4> A typical example of a fuel cell is a polymer electrolyte fuel cell (PEMFC: Polymer).

Electrolyte Membrane Fuel Cell) and Direct Oxidation Fuel Cell. When methanol is used as a fuel in the direct oxidation fuel cell, it is called a direct methanol fuel cell (DMFC).

Although a number of research and development examples of electrode catalysts for fuel cells have been reported, the trends up to now have focused on improving catalyst activity, and in recent years, many efforts have been made to improve durability in terms of practical use.

In the conventional catalyst, a supported catalyst was used to increase the inertness (activity per catalyst weight), but it was difficult to secure the catalyst durability by causing the support structure destruction in the process of increasing the support for high dispersion of the catalyst. For this reason, there have been cases of attempting to strengthen the support durability by detonating the carbon support, but there is a problem in that it is not effective in terms of catalyst activity due to the difficult process and the difficulty of supporting the catalyst itself.

<7> _. On the other hand, porous materials that are advantageous in terms of mass transfer, such as mesoporous carbon, have also suffered from structural weakness. Recently, a case of developing a catalyst utilizing nanoparticles or nanofibers, which can give a high specific surface area as a so-called open surf ace, as a carrier Although has been reported, this is also a situation that does not obtain effective results due to the difficulty of supporting and dispersing the catalyst. [Detailed Description of the Invention]

[Technical problem]

It is an object of the present invention to provide a carbon nanomaterial having excellent durability and capable of supporting a catalyst more efficiently and having excellent performance as a catalyst carrier.

The present invention also aims to provide a method for producing the carbon nanomaterial.

Technical Solution

According to an embodiment of the present invention, a carbon nanomaterial including carbon nanofibers including nitrogen is provided.

<π> According to another embodiment of the present invention, the step of introducing a nitrogen gas, in the presence of a metal catalyst supported on a carrier in a reaction vessel; Raising the temperature while supplying a mixed gas of nitrogen gas and hydrogen gas to the reaction vessel; And supplying a nitrogen-containing compound to the reactor.

Advantageous Effects

The carbon nanomaterial according to the present invention has excellent durability and can support a catalyst more efficiently, and thus has excellent performance as a catalyst carrier. The carbon nanomaterial of the present invention has an advantage of having excellent durability due to excellent crystallinity, carrying a catalyst more effectively, and improving dispersibility by introducing nitrogen into carbon nanofibers.

The carbon nanomaterial of the present invention is expected not only to be used as a support for a catalyst including an electrode catalyst of a fuel cell but also to be used for introduction and development in various fields.

[Brief Description of Drawings]

1 is a view schematically showing the structure of a half-unggi used in the present invention.

2 is a view showing the temperature and feed gas composition profile of the reaction process performed in the embodiment of the present invention.

FIG. 3 is a graph showing N / C (atomic%) according to the synthesis yield and elemental analysis of the nitrogen-doped carbon nano-rubber prepared according to Examples 1 to 11. FIG.

4 is a cross-sectional view of nitrogen-doped carbon nanofibers prepared according to Examples 1 to 11.

SEM picture.

5 is a sum of carbon nanofibers prepared according to Examples 4, 7, 10, and 12 to 15; Graph showing sexual yield.

FIG. 6 is an SEM photograph of carbon nanofibers prepared according to Examples 4 and 12.

FIG. 7 is a TG measurement graph of carbon nanofibers prepared according to Examples 2, 5, 7, 10, and 11. FIG.

FIG. 8 is a graph of measuring the specific surface area of carbon nanofibers prepared according to Examples 1-11.

9 is an XPS (X-ray Photoelectron) for nitrogen of the carbon nanofibers of Example 3

Spectroscopy Graph showing spectral results.

FIG. 10 is an XPS (X-ray Photoelectron) for nitrogen of the carbon nanofibers of Example 7. FIG.

Spectroscopy Graph showing spectral results.

FIG. 11 is a graph showing the total nitrogen content of the Hanso nanofibers prepared according to Examples 1 to 11 and the nitrogen content present on the surface of the carbon nanofibers.

FIG. 12 shows N / C atomic ratios and (B) component (graphite-like structure) / (A) component (pyridine-like structure) on the surface of carbon nanofibers prepared according to Examples 1 to 11. Graph showing the ratio.

FIG. 13 is an X-ray diffraction (XRD) measurement graph of carbon nanofibers prepared according to Examples 1 to 11.

FIG. 14 is a graph showing the distance between d002 plane and Lc (002) crystal size of carbon nanofibers prepared according to Examples 1 to 11. FIG.

15 is a graph showing the results of cyclic voltametry experiments measured using working electrodes using the carbon materials of Examples 4, 7 and 10, and Comparative Examples 2 to 4. FIG. 16 is a graph showing the results of oxygen reduction reaction experiments using the working electrode using the carbon material of Examples 4, 7 and 10, and Comparative Examples 2 to 4.

17 is a graph showing the results of cyclic voltametry experiments measured using an operating electrode using a catalyst prepared according to Examples 16 to 18 and Comparative Examples 5 to 6. FIG. FIG. 18 is a graph showing the results of an oxygen reduction reaction test measured using a working electrode using a catalyst prepared according to Examples 16 to 18 and Comparative Examples 5 to 6. FIG.

Best Mode for Implementation of the Invention

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

The present invention relates to carbon nanomaterials. This carbon material contains nitrogen Carbon nanofibers. In this carbon nanofiber, nitrogen may be present in a doped form and distributed throughout the crystal structure of the carbon nanofiber. As such, the presence of nitrogen in the doped form can prevent the outflow of nitrogen in the blackening condition, and the nitrogen forms a structure with carbon nanofibers, thereby improving durability.

Nitrogen included in the carbon nanofibers may exist in various chemical states. That is, nitrogen is inserted into the carbon structure constituting the carbon nanofiber, pyridine-like

It may be present as an A component having a (pyridine-like) structure or a pyr idine-1 like structure, or may be present as a B component having a -like structure or blood-like structure. It may also be present in combination with oxygen. When measuring carbon nanofibers containing nitrogen according to an embodiment of the present invention by X-ray photoelectron spectroscopy (XPS), the component ratio (B / A) of the B component and the A component is preferably 0.3 to 2.0. , 1.0 to 2.0 is more preferred. When the component ratio (B / A) is included in the above range, it is effective in maintaining the structure of the carbon nanofibers while improving the activity for the oxygen reduction reaction.

The content of nitrogen in the carbon nanofibers may be 0.5 to 10 atomic%. When the content of nitrogen is included in the above range, it is possible to impart sufficient functionality by nitrogen doping and at the same time eliminate the structural vulnerability of the carbon nanofibers by nitrogen doping.

<36>

In the carbon nanofibers, the ratio (N / C) of nitrogen to carbon is preferably 1.0 to 5.0 atomic%. The higher the ratio of nitrogen, the greater the effect of imparting the effects of nitrogen, but too high the ratio of nitrogen acts as a defect in the carbon structure, weakening crystallinity. When nitrogen is present in the above range compared to carbon, it is possible to obtain a doping effect of nitrogen in a highly crystalline structure.

The carbon nanofibers preferably have a herringbone structure. The herringbone structure refers to a state in which the arrangement of graphenes is arranged at a constant angle in a V-shape with respect to the fiber axis in carbon having an abyssal structure having a crystalline structure. That is, the carbon nanofibers exhibit crystallinity. When the carbon nanofibers have a herringbone structure, the edges of the graphite may be exposed to the surface in abundance.

<3> Such carbon nanofibers have a (002) plane peak at 20 to 30 ^° when 2Θ is measured by X-ray diffraction measurement using CuKa. In addition, the surface between the carbon nanofibers The distance d002 is 0.340 to 0.356 mm 3 and the crystal size Lc (002) may be 1 to 7 nm. The average diameter of the carbon nanofibers may be 10 to 100 nm. When the average diameter of the carbon nanofibers falls within the above range, high specific surface area as a carrier can be obtained together with structural durability.

<4i> The carbon nanofibers preferably have a specific surface area of 50 to 500 m ² / g, and more preferably 70 to 490 m ² / g.

The carbon nano material may be manufactured by a manufacturing method according to another embodiment of the present invention. The method includes the steps of introducing nitrogen gas in a reaction vessel, in the presence of a metal catalyst supported on a carrier; Heating the temperature while supplying a mixed gas of nitrogen gas and hydrogen gas to the reaction vessel; And supplying a nitrogen containing compound to the reactor.

Hereinafter, the manufacturing method will be described in detail.

First, nitrogen gas is introduced in the reaction vessel in the presence of a metal catalyst supported on a carrier.

The carrier may be selected from the group consisting of MgO, MgO, Si0 _2l A1 ₂ 0 ₃ , zeolite, aluminosilicate carbon-based materials, and combinations thereof. The carbonaceous material may be natural alum, artificial alum, carbon black, activated carbon, activated carbon fiber, carbon nanotube, carbon nanofiber, or a combination thereof.

In addition, the metal catalyst may be a metal selected from the group consisting of Ni, Fe, Co, and combinations thereof or alloys thereof. The metal catalyst may further include a metal selected from the group consisting of Mo, Cu, Cr, Pt, Ru, Pd, or a combination thereof.

Subsequently, the reactor is heated while supplying a mixed gas of nitrogen gas and hydrogen gas. Hydrogen gas prevents catalyst poisoning in the catalytic chemical vapor deposition (CCVD) process and increases the synthesis yield. When reaction occurs under a simple mixture of hydrogen gas and a carbonizable compound, pyrolysis occurs excessively. Side reactions may occur due to the high reaction rate, and incorporation of an inert gas such as nitrogen gas may induce an appropriate reaction rate for the growth of carbon nanofibers by catalyst reaction.

In this case, the mixing ratio of nitrogen gas and hydrogen gas in the mixed gas is appropriately about 160: 40 cc, but is not limited thereto.

The temperature raising step is a temperature of 300 to 700 ^° C. at a temperature increase rate of 5 to ire / min Until it reaches. If the temperature increase rate is slower than the above range, the synthesis time increases, which leads to a decrease in productivity. Too high a temperature causes difficulty in temperature control.

Then, when the temperature reaches the desired temperature of 300 to 700 ^° C., nitrogen-containing compound is fed to the reactor.

The nitrogen-containing compound may be selected from the group consisting of acetonitrile, acrylonitrile, pi, pyridine and combinations thereof.

In addition, the feed rate of the nitrogen-containing compound for the stable catalytic reaction

0.01 to 0.05 cc / min is appropriate.

Carbon nano material according to an embodiment of the present invention can be usefully used for the cathode electrode for fuel cells.

That is, the cathode electrode for a fuel cell according to another embodiment of the present invention includes the carbon nanomaterial. In general, the cathode electrode includes a cathode catalyst layer and an electrode substrate, and the carbon nanomaterial may be included in the cathode catalyst charge.

In this case, the carbon nanomaterial serves as a carrier of a catalyst causing a reduction reaction by reaction of oxidant, hydrogen ion and electron supplied to the cathode electrode.

As the catalyst, for example, a platinum-based catalyst generally used as a cathode electrode catalyst of a fuel cell may be used.

<57>. The platinum-based catalyst may be platinum, ruthenium, osmium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy or platinum-M alloy (M is Ga, Ti, V, Cr, Mn, Fe, Co, Ni). , At least one catalyst selected from the group consisting of Cu, Zn, Sn, Mo, W, Rh, and Ru). Specific examples of the platinum-based catalyst include Pt, Pt / Ru, Pt / W, Pt / Ni, Pt / Sn, Pt / Mo, Pt / Pd, Pt / Fe, Pt / Cr, Pt / Co, Pt / Ru / W , Pt / Ru / Mo, Pt / Ru / V, Pt / Fe / Co, Pt / Ru / Rh / Ni and Pt / Ru / Sn / W can be used.

When using a carbon nano material according to an embodiment of the present invention as a support, and using a platinum-based catalyst on the support, the supporting process is well known in the art and thus will be described in detail herein. Although omitted, the contents can be easily understood by those in the field.

The cathode catalyst layer may further include a binder resin to improve adhesion of the catalyst layer and transfer hydrogen ions.

It is preferable to use a polymer resin having hydrogen ion conductivity as the binder resin, and more preferably, sulfonic acid group, carboxylic acid group, phosphoric acid group, or phosphate in the side chain. Any polymer resin having a cation exchange group selected from the group consisting of a phonic acid group and derivatives thereof can be used. Preferably, a fluorine polymer, a benzimidazole polymer, a polyimide polymer, a polyetherimide polymer, a polyphenylene sulfide polymer, a polysulfone polymer, a polyether sulfone polymer, a polyether ketone polymer, a polyether- It may include one or more hydrogen ion conductive polymer selected from ether-based polymer or polyphenylquinoxaline-based polymer, more preferably poly (perfluorosulfonic acid), poly (perfluorocarboxylic acid), sulfonic acid Copolymers of tetrafluoroethylene and fluorovinyl ethers containing groups, sulfonated polyetherketone aryl ketones, poly (2,2'-m-phenylene) -5,5'-bibenzimidazoles [poly (2 , 2'—in—phenylene) —5,5'-bibenzimidazole] or poly (2,5—benzimidazole) comprising at least one hydrogen ion conductive polymer The can be used.

<6i> The hydrogen ion conducting polymer may contain H, Na, K,

It may also be substituted with Li, Cs or tetrabutylammonium. In case of substituting H with Na in the ion-exchange group of the side chain terminal, NaOH is substituted for the preparation of the catalyst composition, and tetrabutylammonium hydroxide is substituted with tetrabutylammonium, and K, Li or Cs is also appropriate. Substitutions may be used. Since this substitution method is well known in the art, detailed description thereof will be omitted.

The binder resin may be used in the form of a single substance or a mixture, and may also be optionally used with a nonconductive compound for the purpose of further improving adhesion to the polymer electrolyte membrane. It is preferable to adjust the usage-amount so that it may be suitable for a purpose of use.

Examples of the nonconductive compound include polytetrafluoroethylene (PTFE), tetrafluoroethylene-nucleated fluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro alkylvinyl ether copolymer (PFA), and ethylene. Tetrafluoroethylene

(ethylene / tetrafluoroethylene (ETFE)), ethylenechlorotrifluoro-ethylene copolymer (ECTFE), polyvinylidene fluoride, copolymer of polyvinylidene fluoride-nuclear fluoropropylene (PVdF-HFP), dodecyl More preferably one or more selected from the group consisting of benzenesulfonic acid and sorbbi (Sorbitol).

The electrode substrate plays a role of supporting the electrode and diffuses the fuel and the oxidant into the catalyst layer so that the oxidant can easily access the catalyst layer. The electrode substrate is a conductive substrate, and representative examples thereof include carbon paper, carbon cloth, carbon felt, or metal cloth (metal in fiber state). The metal film is formed on the surface of the cloth formed of a porous film or polymer fibers consisting of) may be used, but is not limited thereto.

In addition, it is preferable to use a water-repellent treatment with a fluorine-based resin as the electrode base material, since it is possible to prevent the reactant diffusion efficiency from being lowered by water generated when the fuel cell is driven. Examples of the fluorine resin include polytetrafluoroethylene, polyvinylidene fluoride, polynuclear fluoropropylene, polyperfluoroalkyl vinyl ether, polyperfluorosulfonyl fluoride alkoxy vinyl ether, and fluorinated compounds. Fluorinated ethylene propylene, polychlorotrifluoroethylene or copolymers thereof can be used.

In addition, it may further include a microporous layer for enhancing the effect of the semi-aungmul diffusion in the electrode substrate. These micropores are generally conductive powders of small particle size, such as carbon powder, carbon black, acetylene black, activated carbon, carbon fiber, fullerene, carbon nanotubes, carbon nanowires, carbon nano scars. -horn) or it may include a carbon ^nano ring (carbon nano ring).

The microporous layer is prepared by coating a composition comprising a conductive powder, a binder resin, and a solvent on the electrode substrate. Examples of the binder resin include polytetrafluoroethylene, polyvinylidene fluoride, polynuclear fluoropropylene, polyperfluoroalkyl vinyl ether, polyperfluorosulfonyl fluoride, alkoxy vinyl ether, polyvinyl alcohol, and cells. Loose acetate or copolymers thereof and the like can be preferably used. As the solvent, alcohols such as ethane-isopropyl alcohol, n-propyl alcohol, butyl alcohol, etc., water, dimethylacetamide, dimethyl sulfoxide, N-methylpyridone, tetrahydrofuran, etc. may be preferably used. . Depending on the viscosity of the composition, the coating process may be used, such as screen printing, spray coating or coating using a doctor blade, but is not limited thereto.

<68>

In the above description, the case where the carbon nanomaterial of the present invention is used as a catalyst carrier of a cathode electrode of a fuel cell has been described. However, the carbon nanomaterial of the present invention can be used as a carrier of various other catalysts, and furthermore, to develop materials in various fields. It can be widely used.

<70>

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention and the present invention is limited by the following examples. It is not.

(Example 1)

<73> * Preparation of catalyst for carbon nanofibers

<74> 8.426 g of iron nitride (iron (II) nitrate, Sigma-Aldrich, Assay 98.0%) was distilled water

It was dissolved in 14.857g to prepare an aqueous solution of iron nitride, 7.34g of nickel nitride (nickel nitrate, Sigma-Aldrich, Assay 99.0%) was dissolved in 13.272g of distilled water to prepare a nickel nitride aqueous solution, magnesium nitrate (magnesium nitrate) Hexahydrate, Junsei Chemical, Assay 97.0%) 9.935g was dissolved in 9.524g of distilled water to prepare an aqueous solution of magnesium nitride hexahydrate.

The aqueous solutions and citric acid were added to a 100 ml beaker. At this time, the amount of citric acid was used to be 0.625 times the total moles of metal contained in the aqueous solution.

Subsequently, after placing the mixture in a furnace, the phase was 150 over 1 hour at (25 ^° C).

^It heated up to ^° C and maintained the temperature for 10 minutes to remove moisture. The obtained product was sharply crushed, pulverized finely, and then heated up to 18 CTC. After holding for 2 hours at 180 ^° C, it was crushed and finely ground in a mortar. The milled product was heated to 350 ^° C. over 2 hours, then maintained at 350 ^° C. for 1 hour, finely ground and finely ground at the mortar to prepare a MgO ocher colored catalyst supported on NiFe catalyst. At this time, the molar ratio of Ni: Fe: MgO was 4: 1: 5.

* Preparation of Nitrogen-doped Carbon Nanofibers

The semi-unggi shown in FIG. 1 was prepared.

About 100 mg of the MgO catalyst carrying the NiFe catalyst prepared above was evenly spread on the alumina plate to a width of 3 × 3cu. The alumina plate prepared by evenly spreading the catalyst was placed in the center of the quartz stream of the reactor shown in FIG. 1 and then sealed using Teflon tape.

Next, the following process was performed according to the temperature and feed gas composition profile as shown in FIG. 2.

A moisture trap was installed at the nitrogen gas outlet to remove moisture in the quartz tube and nitrogen gas.

In order to sufficiently purge the inside of the quartz stream with nitrogen at room temperature, nitrogen gas was supplied at 200 cc / min for 15 minutes.

Subsequently, while raising the quartz tube to the reaction temperature (300 ^° C.) for 1 hour, Nitrogen gas and hydrogen gas were supplied into the quartz tube at a supply amount of 160 cc / min and 40 cc / min, respectively.

When the reaction temperature was reached, 0.035 ml / min of acetonitrile was supplied through the micropump and maintained for reaction time. At this time, nitrogen-doped carbon nanotubes were formed.

Subsequently, natural gas was cooled down to room temperature while supplying nitrogen gas to the quartz tube in a supply amount of 160 cc / min. Subsequently, the formed nitrogen-doped carbon nano-lives were collected.

The collected nitrogen-doped carbon nanotubes were mixed with 120 g of HCl and 300 g of distilled water, and the mixture was sealed and stirred for 24 hours. HC1 and distilled water were removed from the stirred product, 10% by weight of HC1 was added again, followed by further stirring for 24 hours. Subsequently, the stirred product was sufficiently washed with distilled water and filtered to obtain a carbon nano-leube doped with nitrogen.

(Example 2)

Carbon nanotubes doped with nitrogen were prepared in the same manner as in Example 1 above, except that the reaction temperature of the step of raising the temperature of the quartz rib was performed to 340 ^° C.

(Example 3)

Carbon nanotubes doped with nitrogen were prepared in the same manner as in Example 1, except that the reaction temperature of the quartz tube was raised to 380 ^° C.

(Example 4)

Nitrogen-doped carbon nanotubes were prepared in the same manner as in Example 1 except that the reaction temperature of the quartz tube sublimation process was performed up to 42 CTC.

(Example 5)

Nitrogen-doped carbon nanotubes were prepared in the same manner as in Example 1, except that reaction temperature of the quartz tube was raised to 460 ^° C.

(Example 6)

Nitrogen-doped carbon nano-Lube was prepared in the same manner as in Example 1 except that the reaction temperature of the process of subliming the quartz tube was 5 (xrc). It was.

<97> (Example 7)

Carbon nanotubes doped with nitrogen were prepared in the same manner as in Example 1, except that reaction temperature of the process of subliming the quartz tube was performed up to 52 CTC.

(Example 8)

Nitrogen-doped carbon nanotubes were prepared in the same manner as in Example 1 except that the reaction temperature of the process of raising the temperature of the quartz rib was performed up to 540 ^° C.

<ιοι> (Example 9)

Carbon nanotubes doped with nitrogen were prepared in the same manner as in Example 1 except that the reaction temperature of the process of heating the quartz tube was performed up to 600 ° C.

(Example 10)

Nitrogen-doped carbon nano-Lube was prepared in the same manner as in Example 1, except that the reaction temperature of the process of raising the quartz tube was performed up to 640 ^° C.

(Example 11)

Carbon nanotubes doped with nitrogen were prepared in the same manner as in Example 1 except that the reaction temperature of the step of raising the temperature of the quartz tube was performed up to 680 ^° C.

(Example 12)

Nitrogen-doped carbon nanotubes were prepared in the same manner as in Example 4 except that the reaction was maintained at a reaction temperature (42C C) for 3 hours (reaction time).

(Example 13)

<πο> Nitrogen-doped carbon nanotubes were prepared in the same manner as in Example 7, except that the reaction was maintained at a reaction temperature (52 CTC) for 3 hours (reaction time).

<ιπ> (Example 14)

Carbon nanotubes doped with nitrogen were prepared in the same manner as in Example 10 except that the reaction was maintained at a reaction temperature (640 ^° C.) for 3 hours (reaction time).

(113) (Example 15)

<ιΐ4> above, except that the reaction was maintained at a reaction temperature (64 CTC) for 5 hours (reaction time). Carbon nanotubes doped with nitrogen were prepared in the same manner as in Example 10.

<115> (Comparative Example 1)

The semi-unggi shown in FIG. 1 was prepared.

About 100 mg of the MgO catalyst carrying the prepared NiFe catalyst was evenly spread on the alumina plate to a width of 3 × 3cuf.

Subsequently, the alumina plate prepared by spreading the catalyst evenly was placed in the center of the semi-ungung quartz tube shown in FIG. 1 and then sealed using Teflon tape.

A moisture tram was installed at the outlet of the helium gas to remove moisture in the quartz tube and helium gas.

To sufficiently purge the inside of the quartz tube with helium gas at room temperature, helium gas was supplied at 200 cc / min for 15 minutes.

The quartz tube was then heated to the reaction temperature (30 (rC) for 1 hour while helium gas and hydrogen gas were supplied in a 4: 1 volume ratio into the quartz stream.

When the reaction temperature was reached, 0.035 ml / min of acetonitrile was supplied through the micropump and maintained at the reaction temperature for 1 hour (reaction time). At this time, carbon nanotubes doped with nitrogen were formed.

Subsequently, natural gas was cooled to room temperature while supplying nitrogen gas to the quartz stream in a supply amount of 160 cc / min. Subsequently, the formed nitrogen-doped carbon nanotubes were collected.

The collected nitrogen-doped carbon nanotubes were mixed with 120 g of HC1 and 300 g of distilled water, and the mixture was sealed and stirred for 24 hours. HC1 and distilled water were removed from the stirred product, and HC1 at a concentration of 10% by weight was added again, followed by further stirring for 24 hours. Subsequently, the stirred product was sufficiently washed with distilled water and filtered to obtain a carbon nanotube doped with nitrogen.

Carbon nanotubes doped with nitrogen were prepared in the same manner as in Example 1 except that the reaction temperature of the step of raising the temperature of the quartz tube was performed up to 420 ^° C.

* Synthetic yield and N / C (atomic%)

Synthesis yield of N-doped carbon nanotubes prepared according to Examples 1 to 11 and N / C (atomic «are shown in Fig. 3) according to elemental analysis results. The amount of carbon produced compared to the amount of catalyst used in TGCThermal Gravimetry) was calculated based on the measurement results. In addition, elemental analysis was measured using a combustion method that analyzes the composition of each element by quantifying the gas generated during combustion.

As shown in FIG. 3, the yield is extremely low ^{at the} reaction temperature of 300 ^° C. (Example 1), whereas the production yield is rapidly increased at 340 ^° C. (Example 2), and the reaction temperature is 420 ^°. Slightly increased to C. In addition, the synthesis yield showed a marked decrease trend up to the reaction temperature of 520 ^° C, showed almost the same yield in the range of 520 ^° C to 650 ^° C, and then rapidly decreased at 680 ^° C.

In addition, the N / C (atomic%) is continuously increased from 300 ^° C (Example 1) to 520 ^° C (Example 7), and slowly decreases to 650 ^° C, 680 ^{At °} C, it showed a tendency to decrease rapidly.

<130>

<i3i> * SEM photo

SEM pictures of the nitrogen-doped carbon nanofibers prepared according to Examples 1 to 11 were measured and the results are shown in FIG. 4.

As shown in Figure 4, it can be seen that the reaction temperature is not yet equipped with the shape of the fiber at 340 ^° C or less.

The carbon nanofibers prepared according to Example 3 having a reaction temperature of 380 ^° C. are 30 to

It can be seen that fibers with a very uniform average diameter of size 40 nm were formed. In addition, it can be seen that the higher the reaction temperature, the longer the length of the fiber. When the reaction temperature is 540 ^° C or more, the fiber length distribution is similar, but as the reaction temperature increases, it can be seen that rather thick fibers of 70 to 100 nm average diameter appear.

<135>

* Synthetic yield over reaction time

The synthetic yields of the carbon nanofibers prepared according to Examples 4, 7, 10 and 12 to 15 were measured and the results are shown in FIG. 5.

As shown in FIG. 5, it can be seen that the amount of synthesis increases as the reaction time increases at each reaction temperature.

<139>

<140> * SEM picture

<i4i> SEM photographs of the carbon nanofibers prepared according to Examples 4 and 12 are shown in FIG. 6. As shown in FIG. 6, the fiber length of the carbon nanofibers having a reaction time of 3 hours is longer than that of the carbon nanofibers prepared in Example 4 having a reaction time of 1 hour. You can see that it broke.

<142>

<143> * TG measurement

For carbon nanofibers prepared according to Examples 2, 5, 7, 10, and 11, TG was measured using a TG analyzer (device: STA 409 PC, NETZSCH) under an air atmosphere. The TG measurement using the samples 10mg supplied to the TG analyzer, and the drying air to 30cc / min, and after heating to 5K / min from room temperature to 100 ^° C, such as 30 minutes at 100 ^° C is (isothermal) status After maintaining, removing moisture and stabilizing the state, the temperature was measured at a temperature of 5 K / min from 100 ^° C to 900 ° C.

The results are shown in FIG. As shown in Figure 7, it can be seen that the higher the reaction temperature, the better the oxidation resistance.

<146>

<147> * BET measurement

Nitrogen isotherm adsorption and desorption experiments were performed on the carbon nanofibers prepared according to Examples 1 to 11 to measure specific surface areas. Nitrogen isothermal adsorption and desorption experiment

Belsorp-II mini (Nihon Bell) was used and pressure range p / _P 0 = 0 to 0.99, adsorption / desorption range. In addition, the sample was prepared by treating the prepared carbon nanofibers in a 10 wt% HC1 solution for 48 hours, washing with distilled water and drying for 3 hours in a drying oven at 80 ^° C. The measured specific surface area results are shown in FIG. 8. As shown in FIG. 8, the carbon nanofibers prepared according to Examples 1 to 11 obtained specific surface areas in the range of about 70 to 480 m 7 g. In addition, as can be seen in Figure 8, it can be seen that the specific surface area tends to decrease slightly as the reaction temperature increases.

<149> * XPS measurement

In order to observe the surface chemical properties of the carbon nanofibers prepared according to Examples 1 to 11, XPS (X—ray Photoelectron Spectroscopy) analysis was performed. In the XPS analysis, the carbon, nitrogen, and oxygen components of each sample were analyzed at binding energy (C: 280 to 295 eV, N: 393 sowl 410 eV, 0: 520 to 540 eV). Among the results, XPS spectrum results for nitrogen of the carbon nanofibers of Examples 3 and 7 are shown in FIGS. 9 and 10. (A), (B) and (C) shown in FIGS. 9 and 10 are pyridine-like structures or pyridine-like structures nitrogen components (A) and graphite-like, respectively. Corresponding to the structure or pyrrole-like structure nitrogen component (B) component and nitrogen component (C) combined with oxygen, respectively. As a result, there are three forms of nitrogen in the manufactured carbon nanofibers. It can be seen that it exists.

In addition, for the carbon nanofibers prepared according to Examples 1 to 11, the total nitrogen content measured from the measured XPS results and the nitrogen content present on the carbon nanofiber surface are shown in FIG. 11. . As shown in FIG. 11, the nitrogen content (about 1 to 9 atom ¾) present on the surface is higher than the total nitrogen content (about 1 to 5 atom%), and the N / C atomic ratio at the surface is the total N / C source. It can be seen that about two times higher than mercy. Since the actual catalyst reaction is made on the surface of the catalyst and the carrier, the composition of the surface is important, and if there is more nitrogen on the surface of the total nitrogen content, the effect of nitrogen on the reaction can be seen more.

In addition, the ratio of N / C atomic ratio and the component (B) (graphite-like structure) / (A) component (pyridine-like structure) at the measured surface is shown in FIG. 12. As shown in FIG. 12, it can be seen that as the reaction temperature increases, the relative -nitrogen nitrogen component increases relatively.

<153> * Degradation Analysis

In order to confirm the degree of crystallization (crystallinity) of the carbon nanofibers prepared according to Examples 1 to 11, X-ray scarcity (XRD) analysis was performed. XRD analysis was performed using RINT2000 (Rigaku) and scanning speed of 0.02 per minute from 10 degrees ( ^° ) to 80 degrees ( ^° ) in 2Θ / Θ scanning mode. Among the measurement results, 2Θ shows a peak corresponding to the (002) lattice plane near 26 degrees Γ) in FIG. 13. As shown in FIG. 13, Examples 1 to 2. FIG. Carbon nanofibers prepared according to 11 can be seen that the peak of the (002) plane appears. In addition, it can be seen that as the reaction temperature increases, the peak central axis moves to a high angle, and the peak width narrows, thereby increasing the crystallinity. In addition, as the reaction temperature increases, the 10-band becomes apparent.

In addition, in the XRD results shown in FIG. 13, the determination parameter for the peak of the (002) plane is

Bragg's equation (interface distance determination) and Scherrer equation (crystal size determination) were calculated, and the results of d002 interplanar distance and Lc (002) crystal size are shown in FIG. 14. As shown in FIG. 14, as the reaction temperature increases until the reaction temperature of 50 CTC increases, d002 increases rapidly and similarly appears above 0.341-0.43 nm at higher temperatures, but Lc (002) is dependent on the reaction temperature. The linear increase was about 2 nm ^at the reaction temperature of 300 ^° C and about 6 nm ^{at the} reaction temperature of 680 ^° C. As a result, it can be seen that the crystallinity of the prepared carbon nanofibers is very excellent compared to the general carbon block.

<156> * Electrochemical Characterization A catalyst slurry was prepared by mixing 20nig of carbon nanofibers prepared in Examples 4, 7 and 10, 10 wt% ¾ concentration Napi silver solution (water solvent, Dupont) 40 ≠, distilled water 40kPa and ethanol lg. It was. The catalyst slurry was coated with 10, glass carbon having an IcHf area, and dried to prepare a working electrode.

Carbon black (Cabot) in place of the carbon nano-leube prepared in Example 2 as Comparative Example 2

A working electrode was prepared in the same manner as described above using Vulcan XC72R).

<159> Plate Type Instead Of Carbon Nano-Luv Prepared In Example As Comparative Example 3

A working electrode was prepared in the same manner as described above using CNFCSsuntel RP-610: CNF1).

A working electrode was prepared in the same manner as described above using carbon nanofibers (CNF 2) synthesized at 52 CTC using ethylene as a carbon source instead of the carbon nanotubes prepared in Example 4 as a comparative example.

<i6i> Working electrode manufactured, platinum mesh with counter electrode, Ag / AgCKALS as reference electrode. Electrochemical experiments were carried out with a three-electrode system using RE-IB, standard hydrogen electrode (denoted NHE).

Electrochemical experiments have shown that cyclic voltammetry is 0.1 M, which is thoroughly purged with nitrogen gas.

HC10 ₄ in aqueous solution, was conducted in the 0.0 to 1.2V with NHE reference electrode, an oxygen reduction reaction (Oxygen Reduction React ion: 0RR) experiment in 0.1M HC10 purged sufficiently with oxygen layer ₄ aqueous solution as reference electrode NHE 1.2 to It was carried out at 0.2V. Also, the potential sweep rate was fixed at 2 () mV / sec.

The results of the cyclic voltametry experiment are shown in FIG. 15, and the results of the 0RR experiment are shown in FIG.

16 is shown.

As shown in FIG. 15, Examples 4, 7 and 10, and Comparative Examples 2 to 4, all carbon materials exhibit a rectangular pattern by typical electric double layer formation. Examples 4, 7 and 10 In the case of using carbon nanofibers, it can be seen that the inner area is large. As such, the large internal area indicates a large amount of ion adsorption, which means that the ion adsorption capacity is excellent, and as a result, it can be predicted that the catalyst supporting characteristics and the interaction between the catalyst and the carrier will be excellent when used as a catalyst carrier for fuel cells. have.

In addition, as shown in Figure 16, the carbon nanofibers of Examples 4, 7 and 10 has an oxygen reduction activity, it can be seen that the carbon material of Comparative Examples 2 to 4 does not have an oxygen reduction activity. From this result, the carbon nanofibers of Examples 4, 7 and 10 can It can be seen that it can also be used as a catalyst for the sword electrode.

(166) (Example 16)

A catalyst precursor solution was prepared by stirring a platinum precursor (Chloroplatinic acid hydride 99.9%, Aldrich), a carbon nanofiber carrier prepared according to Example 11, and 400 ml of distilled water for 48 hours.

NaBH ₄ was prepared by dissolving it in 400 ml of distilled water in an amount of 15 times the molar ratio of the amount of metal to be supported. The mixture was stirred well for 30 minutes and then stirred for 48 hours to prepare a NaBH ₄ solution. The catalyst precursor solution was added to NaBH ₄ solution, and stirred for 1 hour to reduce the solution. The reduced product was washed with 1 L of distilled water and filtered, and dried for 2 hours in an oven at 80 ^° C to prepare a Pt / carbon nanofiber catalyst (Pt / N640).

<169> (Example 17)

The platinum precursor (Chloroplatinic acid hydride 99.9%, Aldrich), except that the carbon nanofiber carrier prepared according to Example 13 and 400 ml of distilled water were stirred for 48 hours to prepare a catalyst precursor solution. In the same manner as in Example 16, a Pt / carbon nanofiber catalyst (Pt / N523) was prepared.

<i7i> (Example 18)

Platinum precursor (Chloroplatinic acid hydride 99.9%, Aldrich)

(Palladium (II) chloride 99.9%, Sigma— Aldrich), except that the catalyst precursor solution was prepared by stirring the carbon nanofiber carrier prepared according to Example 13 and 400 ml of distilled water for 48 hours. In the same manner, a PtPd / carbon nanofiber catalyst (PtPd / N523) was prepared. At this time, the weight ratio of platinum and palladium was 1: 2.

<173> (Comparative Example 5)

Pt precursor (Chloroplatinic acid hydride 99.9%, Aldrich), carbon black carrier and 400 ml of distilled water was stirred for 48 hours, except that the catalyst precursor solution was prepared in the same manner as in Example 16, Pt Carbon nanofiber catalysts (Pt / CB) were prepared.

<175> (Comparative Example 6) '

<176> Commercially available platinum-palladium catalysts (JM9000, Johnson Mat they Fuel Cells-Hi pec

Series) was used. At this time, the weight ratio of platinum and palladium was 1: 2.

20 mg, 10 catalyst prepared according to Examples 16 to 18 and Comparative Examples 5 to 6

Nafion solution (water solvent, Dupont) in weight% concentration, ≠ 0, distilled water and ethane Combined to make catalyst slurry. The catalyst slurry was applied to glass carbon 10 and dried thoroughly to prepare an electrode.

Using the prepared electrode, using the H ₂ S0 ₄ as the electrolyte was carried out in the same manner as the cyclic voltametry experiment and oxygen reduction reaction test to obtain a cyclic voltammetry experiment and oxygen reduction reaction test results . The results are shown in FIGS. 17 and 18, respectively. Cyclic voltammetry experiments shown ^'in Figure 17 is the value at 5 cycles, the electrochemically active surface (Electro Chemical Surface Area, ECSA) of the catalyst according to the hydrogen desorption amount is the comparative example 6 is shown the highest value Example 18 showed similar results as in Comparative Example 6.

In addition, as shown in FIG. 18, it can be seen that the catalysts of Comparative Examples 5 and 16 are excellent in activity.

Claims

[Range of request]

[Claim 1]

Carbon nanomaterials comprising carbon nanofibers comprising nitrogen.

[Claim 2]

The method of claim 1,

The nitrogen is a carbon nano material that is doped with carbon nano fibers.

[Claim 3]

Tax in Clause 1

In the carbon nanofibers, the nitrogen content is 0.5 to 10 atomic% carbon nano material.

[Claim 4]

The method of claim 1,

The carbon nanomaterial has a ratio (N / C) of 1.0 to 5.0 atomic% of carbon and carbon in the carbon nanofibers.

[Claim 5]

The method of claim 1,

Wherein the carbon nanofibers have a herringbone structure.

[Claim 6]

According to claim 1,

The carbon nanomaterial has an average diameter of 30 to 100 nm of carbon nanofibers.

[Claim 71

The method of claim 1,

Wherein the carbon nanofibers have a specific surface area of 50 to 500 m ² / g.

[Claim 8]

According to claim 1,

The carbon nanofibers are carbon nanomaterials having a (002) plane peak at 20 to 30 ^° when 2Θ is measured by X-ray diffraction measurement using CuKa.

[Claim 9]

Introducing nitrogen gas in the reactor in the presence of a metal catalyst supported on a carrier;

The temperature is raised while supplying a mixed gas of nitrogen gas and hydrogen gas to the reaction vessel step; And

Supplying a nitrogen-containing compound to the reactor

Method for producing a carbon nano material comprising a.

[Claim 10]

The method of claim 9,

The carrier is selected from the group consisting of MgO, Si0 ₂ , Al ₂ O ₃ , zeolite, aluminosilicate, carbon-based materials and combinations thereof.

[Claim 11]

The method of claim 9,

The metal catalyst is a method of producing a carbon nano material is a metal selected from the group consisting of Ni, Fe, Co and combinations thereof or alloys thereof.

[Claim 12]

The method of claim 9,

The mixing ratio of nitrogen gas and hydrogen gas in the said mixed gas is 160: 40 cc, The manufacturing method of the carbon nanomaterial.

[Claim 13].

According to claim 9,

The supply amount of the mixed gas is 200 cc / min.

[Claim 14]

The method of claim 9,

The step of raising the temperature is carried out until the temperature reaches a temperature of 300 to 700 ^° C. at a temperature increase rate of 5 to ire / min.

[Claim 15]

The method of claim 9,

The nitrogen-containing compound is selected from the group consisting of acetonitrile, acrylonitrile, pi, pyridine and combinations thereof.

[Claim 16]

The method of claim 19,

And a feed rate of the nitrogen-containing compound is 0.035 cc / min.

[Claim 17] The method of claim 7,

Supplying the nitrogen-containing compound is a method of producing a carbon nano material that is carried out at a temperature of 300 to 700 ^° C.

[Claim 18]

A catalyst comprising the carbon nanomaterial according to any one of claims 1 to 8 as a support.