KR20090033288A - Catalyst for low temperature fuel cell using carbon nanofiber as a support, electrode for low temperature fuel cell using the catalyst, and low temperature fuel cell using the catalyst - Google Patents

Abstract

A catalyst for a low temperature fuel cell is provided to maximize the efficiency while increasing the surface area of the dipped platinum catalyst, and to reduce noble metals. A catalyst for a low temperature fuel cell comprises a support and a catalyst. The support is fiber-like nano carbon of highly effective surface area, having the specific surface area measured with a nitrogen BET method of 100 m^2/g or more. The fiber-like nano carbon of highly effective surface area comprises the steps of: (i) manufacturing a transition metal alloy catalyst containing (a) iron single catalyst through oxidation reaction and reduction reaction and (b) at least one metal elected from the group consisting of nickel, cobalt, copper, and molybdenum; (ii) adding hydrogen gas to the catalyst, and performing reduction reaction to produce minute metals on the surface of the catalyst; and (iii) adding C1-4 saturated and unsaturated gas or the mixed gas consisting of carbon monoxide and hydrogen gas and heat-treating them.

Description

Catalyst for low temperature fuel cell using a fibrous nanocarbon as a carrier, electrode for low temperature fuel cell using the catalyst, and low temperature fuel cell using the catalyst {Catalyst for low temperature fuel cell using carbon nanofiber as a support, Electrode for low temperature fuel cell using the catalyst, and Low temperature fuel cell using the catalyst}

The present invention relates to a catalyst for a low temperature fuel cell using fibrous nanocarbon having a carbon nanorod as a basic unit structure as a carrier of a platinum noble metal catalyst, an electrode for a low temperature fuel cell using the catalyst, and a low temperature fuel cell using the catalyst.

A fuel cell converts chemical energy of a fuel directly into electricity through an electrochemical reaction, and exhibits higher efficiency than other energy conversion systems.

Such a fuel cell has a similarity to a primary cell such as a voltaic cell in which electrons are released from one electrode by a chemical reaction and move through an external circuit to the other electrode.

However, there is an important difference between the general cell and the fuel cell. In the general cell, the reactant is contained in the electrode, and as the reaction proceeds, the reactant is chemically converted and gradually extinguished, whereas the fuel cell has a liquid or gas at one electrode. The fuel is continuously supplied in the form, and the other electrode is continuously supplied with oxygen or air from the outside, and thus has an advantage of generating electric energy for a much longer time than a general battery.

Among them, a polymer electrolyte membrane fuel cell (hereinafter referred to as "PEMFC"), which is a low-temperature fuel cell (hereinafter referred to as "low temperature fuel cell"), and a direct methanol fuel cell (DMFC) Is mainly developed for the purpose of portable, home stationary and automotive power.

In particular, they operate at temperatures ranging from room temperature to 100 ° C., unlike other batteries, and have fast startup and response characteristics. In addition, since hydrogen is produced by reforming hydrocarbons such as methanol, ethanol or natural gas as a fuel, the application range for the above use has a wide range of advantages.

On the other hand, PEMFC and DMFC basically need a fuel cell stack (stack), fuel tank and fuel pump.

PEMFC needs a reformer that generates hydrogen gas by reforming fuel in the process of supplying fuel to the stack as compared to DMFC, and generates hydrogen at high temperature using platinum, which is the most active catalyst, as a catalyst of the reformer. As it is purified and used in high purity, it acts as a big factor of price increase. In addition, the high pressure hydrogen tank to replace the reformer has a fatal problem in the stability and materials of the high pressure hydrogen tank. However, since PEMFC uses hydrogen directly, the output characteristics of the PEMFC are much higher than those of DMFC.

On the other hand, DMFC supplying the liquid methanol fuel directly to the stack does not require a reformer, unlike PEMFC, so there is no safety problem of the reformer or the hydrogen tank, and it can be manufactured at a relatively low price, but has a disadvantage in that the output characteristics are poor.

DMFC and PEMFC commonly have a negative electrode (or fuel electrode) that generates hydrogen ions from a raw material using methanol or hydrogen as a raw material with a hydrogen ion conductive electrolyte membrane interposed therebetween, and hydrogen ions and air or oxygen transferred through the electrolyte membrane. It consists of a positive electrode (or air electrode) that reacts the obtained oxygen ions to generate water. In summary, the fuel electrode, the electrolyte membrane, and the air electrode are compressed and manufactured to be called a membrane electrode assembly (hereinafter referred to as "MEA").

However, since the catalyst used in the manufacture of most fuel cells uses a platinum single metal or a platinum-ruthenium alloy as described above, the catalyst has a very expensive problem. Therefore, most of the studies up to now have been conducted for the purpose of maximizing the activity of the catalyst with a limited amount of catalyst, or studies that derive the maximum activity ignoring platinum consumption.

However, it is indispensable for the commercialization of fuel cells to reduce the platinum catalyst price, and the price of the catalyst is directly related to the amount of platinum used. Currently used commercial catalysts are mostly catalysts manufactured and sold by Johnson Matthey and E-TEK.

In particular, Pt-Ru catalyst with platinum and ruthenium and 60 wt% of the total catalyst and 40 wt% carbon carrier is used as the anode catalyst of DMFC, and platinum is 20wt of the total catalyst as the anode catalyst of PEMFC. Pt catalyst having a carbon carrier of 80% by weight is used, and each cathode catalyst uses Pt black having only pure platinum particles dispersed without a carbon carrier.

The present invention is to solve the problems of the conventional low-temperature fuel cell, such as the production cost increase by using such expensive platinum as a catalyst to lower the catalyst manufacturing price, and to extend the life of the catalyst.

Accordingly, the present invention can maximize the effective surface area of the carrier on which the precious metal platinum catalyst can be supported to increase the activity of the precious metal platinum catalyst, and thus, the fibrous nanocarbon carrier composed of carbon nanorods capable of reducing the amount of the precious metal catalyst used. It is possible to reduce the production cost of the catalyst, and to provide a long-life low-temperature fuel cell catalyst, an electrode using the catalyst, and a low-temperature fuel cell through long-term stability of the catalyst.

In addition, an object of the present invention is to provide a low-temperature fuel cell having a higher activity than conventional commercial catalysts by using a catalyst using a fibrous nanocarbon consisting of the carbon nanorods as a catalyst carrier as a fuel electrode.

The fuel cell catalyst prepared using the fibrous nanocarbon having the carbon nanorods as the basic unit structure of the present invention as a catalyst carrier maximizes the effective supported surface area capable of actually supporting platinum on the surface of the carrier, and the surface area of the supported platinum catalyst. In addition, by maximizing the utilization efficiency, using the catalyst prepared as described above, even though the use of the precious metal of the commercial catalyst is lowered from 3mg / ㎠ to 2mg / ㎠ high-performance fuel of 1.5 to 2 times in a single cell Battery manufacturing is possible. In addition, the reduction of the use of precious metals can greatly contribute to lowering the catalyst price, and ultimately can also significantly reduce the price of the fuel cell stack.

The object of the present invention as described above is a carrier; And a catalyst for a low temperature fuel cell comprising a catalyst, wherein the carrier has a specific surface area of 100 m ² / g or more, measured by nitrogen BET method having a nanorod having a diameter of 2 to 8 nm and a length of 4 to 30 nm as a basic unit structure. It is achieved by a catalyst for low temperature fuel cells, characterized in that it comprises fibrous nanocarbon and a catalyst supported on the fibrous nanocarbon carrier having the high effective surface area.

In addition, an electrode for a low temperature fuel cell to achieve another object of the present invention is characterized in that it comprises a metal catalyst supported on a high effective surface area fibrous nano-carbon carrier.

In addition, the low-temperature fuel cell for achieving another object of the present invention is characterized in that it comprises a metal catalyst supported on a high effective surface area fibrous nano-carbon carrier.

Hereinafter, the present invention will be described in more detail.

Hereinafter, a method for preparing the high effective surface area fibrous nanocarbon carrier for preparing a catalyst for a low temperature fuel cell according to the present invention will be described.

First an iron and a metal catalyst through an oxidation reaction and a reduction reaction; Or preparing an alloy catalyst comprising at least one transition metal selected from the group consisting of nickel, cobalt, copper and molybdenum; Reducing gas by adding hydrogen gas to the catalyst to generate metal particles on the surface of the catalyst; And a heat treatment by adding a mixed gas of a saturated and unsaturated gas having 1 to 4 carbon atoms and a hydrogen gas to the catalyst in which the metal fine particles are produced.

This will be described in more detail as follows.

(1) The first step is to prepare an iron single metal or alloy catalyst, which is a catalyst for the production of high effective surface area fibrous nanocarbon carriers having carbon nanorods as a basic unit structure. Specifically, iron carbonate, nickel nitrate, and copper nitrate are reacted with a certain mixed solution with ammonium hydrocarbonate to produce iron carbonate and nickel carbonate-copper.

Iron oxide is prepared by oxidizing the preparation solution in a temperature range of 350 to 500 ° C., followed by oxidation for 30 minutes to 12 hours. Then, a reduction reaction is performed by adding a nitrogen mixed gas containing a sufficient amount of hydrogen gas at 1 to 50 vol.% In the iron oxide at a temperature in the range of 400 to 600 ° C .; Or an alloy catalyst of a transition metal. It is preferred that the finally obtained catalyst used in the preparation of the high effective surface area fibrous nanocarbon contains 5 to 5% by weight of iron.

The second step for producing the high effective surface area fibrous nanocarbon carrier is (2) reducing the prepared catalyst to produce metal particles on the surface thereof, specifically, preparing a predetermined amount of the prepared catalyst on a general horizontal line. After the dispersing apparatus is added, at least one inert mixed gas selected from the group consisting of nitrogen, argon, and helium containing 1 to 50 vol% of hydrogen gas is reduced at 400 to 600 ° C. for 1 to 30 hours to produce the iron. Single catalyst; And metal particles of 2.5 to 60 nm are produced on the surface of the transition metal alloy catalyst.

The third step for preparing the high effective surface area fibrous nanocarbon carrier is (3) a step of preparing fibrous nanocarbon having a nanorod structure by heat-treating the surface of the catalyst on which the metal fine particles are formed with a mixed gas. Specifically, in the temperature range of 350 to 700 ° C. while supplying a saturated and unsaturated gas having 1 to 4 carbon atoms and a mixed gas of carbon monoxide mixed with hydrogen to 5 to 80% by volume on the surface of the catalyst on which the metal fine particles are produced. When heat treated for 1 minute to 48 hours, fibrous nanocarbon having nanorods as a basic structural unit is obtained.

The fibrous nanocarbon having the nanorods of the present invention manufactured as described above as a basic structural unit has a nanorod having a diameter of 2-8 nm and a length of 4-30 nm as shown in FIGS. 1 and 3 below. It is preferable to have it as a basic structural unit. That is, the fibrous nanocarbon according to the present invention is constituted by the basic unit of the nanorod having a three-dimensional pencil-like structure.

Particularly, these unit structures are arranged in a certain direction to form fibrous nanocarbon, so that the surface of the fibrous nanocarbon is formed by the formation of a secondary structure by the unevenness of the cross section of the nanorods, and the edge surface of the carbon hexagonal mesh is exposed to the surface to arrange the fibrous nanocarbon than the base surface. It can be seen that it is composed of many electron densities.

The fibrous nanocarbon composed of nanorods according to the present invention has a concave-convex structure in which metal particles having a size of 2-8 nm can be effectively dispersed on a surface, unlike fibrous nanocarbon composed of basic structural units on a plate. ) And the dispersed metal particles move to the surface during or after the reaction and are entangled with each other to play a role in preventing the reactivity of the metal particles.

The secondary structure and the rich electron density thus formed contribute to the stable dispersion of platinum and ruthenium, and thus finer particles can be dispersed. Also, the dispersed platinum and ruthenium fine particles are not aggregated and stable even in repeated electrochemical reaction By acting as an anchoring site which may exist in a state, it can exhibit higher catalytic activity than carbon nanotubes and carbon black mainly composed of conventional carbon mesh.

The meaning of “high effective surface area” in the high effective surface area fibrous nanocarbon support is actually the surface area on which the catalyst is supported, which is different from the specific surface area measured by the nitrogen BET method.

Usually, in the case of activated carbon, 97% or more of the specific surface area measured by the nitrogen BET method is the specific surface area obtained in the ultrafine pores of 1 nm or less in diameter. However, in the fuel cell catalyst, since the particle size of the platinum particles is 2 to 4 nm, such pores are meaningless because the microscopic pores below 1 nm, such as activated carbon, cannot be supported by the platinum particles. The specific surface area obtained at is excluded from the effective surface area supported by the catalyst. Therefore, the effective surface area is obtained by subtracting the surface area obtained from the small pores into which the catalyst cannot enter, so that the effective surface area is necessarily smaller than the specific surface area measured by the nitrogen BET method.

Unfortunately, the current analytical equipment has not developed an analytical method that can measure only the effective surface area, and the specific surface area measured by the nitrogen BET method is only available because the surface area can only be quantified. Is used in the present invention. Therefore, even if the specific surface area value measured by the nitrogen BET method is used, it is evident that the effective surface area in the present invention is different from the intrinsic specific surface area.

Therefore, compared to the activated carbon which makes the ultrafine pores intensive as mentioned above, in the case of fibrous nanocarbon, the ratio of pores having a larger diameter is relatively high, and in this case, the specific surface area increases relatively effective surface area. .

In other words, the anode catalyst of the low-temperature fuel cell exhibits activity by dispersing ultrafine metal particles on the surface of the carrier. The meaning of the high effective surface area of the carrier is that uniformity and fine dispersibility of the metal due to high dispersion of the metal. It has the meaning of providing a, and to prevent the degradation of the activity due to the catalytic reaction of the dispersed metal particles.

The specific surface area of the present invention means that the specific surface area of the carrier has a high effective surface area of 100 m ² / g or more, preferably 100 to 250 m ² / g.

The catalyst for a low temperature fuel cell according to the present invention is 5 to 95% by weight, preferably 20 to 80% of the high effective surface area fibrous nanocarbon carrier having the platinum single catalyst or the platinum alloy catalyst as the basic structural unit. It is preferable to support the catalytic metal. In the supporting process, platinum or ruthenium chloride is dissolved in water, and reprecipitated using a reducing agent, NaBH _4, to be highly dispersed as fine particles.

Examples of the supported metal catalysts include platinum single metal catalysts or include at least one metal selected from the group consisting of ruthenium, palladium, iridium, osmium, rhodium, molybdenum, tungsten, gold, iron and selenium A platinum-alloy catalyst is used, wherein the molar ratio of the platinum-alloy catalyst to other metals mixed with platinum is preferably 1: 0.5 to 1: 2, but is not limited thereto. Among these, a platinum-ruthenium alloy catalyst is especially preferable.

A method of preparing a fuel cell catalyst by supporting a platinum or platinum alloy catalyst on the surface of the high effective surface area fibrous nanocarbon having the nanorods as a unit structure is prepared using impregnation and chemical reduction methods, which are widely known as the most common methods. do. At this time, NaBH ₄ is used as a reducing agent, and precursors of platinum and ruthenium are (NH ₃ ) ₄ Pt (NO ₃ ) ₂ and (NH ₃ ) ₆ RuCl ₃ , or H ₂ PtCl ₆ .6H ₂ O and RuCl ₃ .nH ₂ O and the like are dissolved in distilled water, mixed with the fibrous nanocarbon carrier, added to a NaBH ₄ solution, reduced, washed, filtered and dried.

Meanwhile, in the present invention, a catalyst having a platinum catalyst or a platinum alloy catalyst supported on a fibrous nanocarbon carrier having the nanorods as a basic unit structure is used as an electrode of a low temperature fuel cell. The fuel cell using the electrode according to the present invention is a structural feature of the fibrous nanocarbon carrier of the present invention, the performance is improved, and the cost of the fuel cell stack can be significantly reduced by reducing the amount of platinum catalyst used. .

Hereinafter, the present invention will be described in more detail based on the following examples, but the present invention is not limited thereto.

Example  1: carbon Nanorods  With basic unit structure High fidelity  Surface area Fibrous On nanocarbon Supported  Preparation of Platinum-Ruthenium Alloy Catalysts

(1) Preparation of fibrous nanocarbon carrier having a nanorod structure

73 g of iron nitrate was dissolved in 300 g of distilled shoe, mixed with stirring, and 31 g of ammonium hydrocarbonate was added until a precipitate was formed. The formed precipitate (iron carbonate) was filtered using filter paper, and then washed twice with distilled water at about 50 ° C. and once with ethyl alcohol to remove excess ammonium hydrocarbonate, followed by 80 ° C. using a vacuum dryer. Dried for 8 hours.

The dried precipitate was oxidized in air at 400 ° C. for 5 hours using a vertical or horizontal furnace to obtain iron oxide. The iron oxide was reduced by using a nitrogen mixed gas containing 20 vol% of hydrogen gas again using a heating furnace at 20 ° C. for 20 hours to prepare an iron catalyst. The iron catalyst prepared above was treated with a nitrogen mixed gas having an oxygen content of 5 vol% for 1 hour at room temperature and passively stored at the surface of the iron catalyst.

The iron (Fe) catalyst was evenly dispersed on a quartz tube having a diameter of 5 cm, and a mixed gas containing carbon monoxide and 20 vol.% Hydrogen gas was injected at 200 sccm (cc amount introduced per minute), followed by heat treatment at 600 ° C. for 2 hours. To prepare a fibrous nano-carbon carrier having a carbon nanorod as a structural unit, the specific surface area is 250m ² / g.

At this time, by using a 0.5g iron catalyst for 4 hours to react 50g, 8 hours to prepare a fibrous nanocarbon having a carbon nanorod of 200g as a structural unit, the surface structure of the prepared fibrous nanocarbon scanning electron Measured under a microscope, the results are shown in Figure 1 below. As can be seen in the following 1, it is composed of the base unit of the nanorod having a three-dimensional pencil-like structure, and has a structure stacked almost perpendicular to the axial direction of the fibrous nanocarbon, the nanorod is It is composed of about 2-8nm in diameter and 4-30nm in length, it can be confirmed by the photograph of Figure 1 that the fibrous nano-carbon is made by the arrangement of this unit structure.

(2) Specific Effective Surface Area Fibrous Nanocarbon On the carrier Supported  Preparation of Platinum-Ruthenium Alloy Catalysts

1 g of the fibrous nanocarbon prepared above, 1.18 g of H ₂ PtCl ₆ .6H ₂ O, and 0.55 g of RuCl ₃ · 2H ₂ O were mixed in 20 cc of water, and dissolved with stirring. This solution was added dropwise to 0.5 mol NaBH ₄ and stirred to prepare a catalyst for a low-temperature fuel cell of 40 wt% PtRu after washing, filtration and drying after reduction.

(3) Production of electrodes and batteries for low temperature fuel cells

A slurry was prepared by mixing 1 g of the catalyst and 20% by weight of Nafion solution, and the slurry was 5 mg / cm 2 (Pt 1.33, Ru 0.77, carbon 3 mg) in carbon paper (2.5x2.5 cm 2) manufactured by Toray. / Cm 2) was applied with a brush to prepare a fuel electrode electrode.

All catalysts using fibrous nanocarbon were prepared by 40 wt% of platinum-ruthenium, and used Nafion 115 membrane, and were pressurized at a temperature of 100 Kg / cm 2 at 135 ° C. for 10 minutes using a high temperature press. All MEA cathode electrodes were coated with Pt black 6mg / cm2 by Johnson Matthey.

DMFC unit cell activity was measured at 30, 60 and 90 ° C, 2M methanol solution at 4ml / min in anode and 200ml / min at cathode in cathode. 2 is shown. As can be seen in the voltage-current curve of FIG. 2, the current densities at 0.4 V (volts) at 30, 60, and 90 ° C. are 116, 328, and 549 mA / cm 2, respectively. power density) of 72, 140 and 246 mW / cm 2, respectively.

In addition, the present invention compared to PtRu 60% by weight of the commercial catalyst 5mg / ㎠ (Pt / Ru / Carbon black = 2/1 / 2mg / ㎠), PtRu 40% by weight of the catalyst reduced the use of precious metals 5mg / ㎠ (PtRu /Ru/C(Carbon))=1.33/0.77/3mg/cm 2), the electrode activity was confirmed to be excellent.

Example  2

Instead of using iron nitrate alone in the preparation of the fibrous nanocarbon carrier having a nanorod structure, 8 g of copper nitrate and 40 g of nickel nitrate were dissolved in 300 g of distilled water, stirred and mixed, and then ammonia hydrocarbonate until precipitation was formed. A catalyst for preparing fibrous nanocarbon was prepared in the same manner as in Example 1 except that 29 g was added.

The prepared catalyst was uniformly dispersed on a 30 cm diameter quartz reactor and heat-treated at 600 ° C. for 2 hours while introducing 3000 sccm of a mixed gas of ethylene and 10 vol% hydrogen to prepare a fibrous nanocarbon having carbon nanorods as a structural unit. The specific surface area at this time is 100 m ² / g.

At this time, 0.5g of an iron catalyst was used for 2 hours to prepare fibrous nanocarbon having 150g of carbon nanorods as a structural unit, and the surface structure of the prepared fibrous nanocarbon was measured by a scanning electron microscope. The results are shown in FIG. 3. Next, as can be seen in Figure 3, the three-dimensional nanorods having a pencil-like structure consisting of three, the nanorods in two directions having a constant square with respect to the axial direction of the fibrous nanocarbon is a fish bone and It has a structure that is stacked in the same form, the nanorods are composed of about 2-8nm in diameter, 4-30nm in length, it can be observed in Figure 3 that the fibrous nanocarbon is made by the arrangement of this unit structure Can be.

A low-temperature fuel cell catalyst was prepared in the same manner as in Example 1 using 1 g of the prepared fibrous nanocarbon, and the voltage-current curve of the DMFC unit cell measurement result using the dicatalyst is shown in FIG. 4. As can be seen from the voltage-current curve of FIG. 4, the current densities at 0.4 volts at 30, 60, and 90 ° C. are 86, 262, and 419 mA / cm 2, respectively, and the highest power densities are 62, 122, and A result of 197 mW / cm 2 was obtained.

In addition, the present invention compared to the commercial catalyst 5mg / cm 2 (Pt / Ru / Carbon black = 2/1 / 2mg / cm 2) of PtRu 60% by weight, 5mg / cm 2 (40% by weight of PtRu catalyst having reduced precious metal usage) Pt / Ru / C (Carbon)) = 1.33 / 0.77 / 3 mg / cm 2), but the electrode activity was confirmed to be excellent.

Comparative example  One : PtRu  60% by weight Johnson Matthey Activity Evaluation of Commercial Catalysts

Purchasing a commercial catalyst of 60% by weight of PtRu manufactured by Johnson Matthey, which used Vulcan XC-72 carbon black, which is the most widely used fuel cell catalyst carrier, was used as a catalyst carrier, 5 mg / cm 2 (Pt / Ru / Carbon black = 2/1/2 mg / cm 2) was prepared and used in the same manner as in Example 1- (3). The voltage-current curve of the result of evaluating unit cell activity is shown in FIG. 5. As can be seen in the voltage-current curve of FIG. 5, the current densities at 0.4 volts at 30, 60, and 90 ° C. are 50, 222, 318 mA / cm 2, respectively, and the highest power densities are 55, 121, A result of 162 mW / cm 2 was obtained.

Comparative example  2 : PtRu  60% by weight of E- TEK Activity Evaluation of Commercial Catalysts

As a fuel cell catalyst carrier, PtRu 60% by weight of a commercial catalyst manufactured by E-TEK using Vulcan XC-72 carbon black, which is generally used as a catalyst carrier, was purchased. The voltage-current curve of the MEA prepared in the same manner and the activity of the unit cell was evaluated in FIG. 6. As can be seen in the voltage-current curve of FIG. 6, the current densities at 0.4 volts at 30, 60, and 90 ° C. are 44, 210, and 265 mA / cm 2, respectively. A result of 140 mW / cm 2 was obtained.

On the other hand, the results of the single cell activity evaluation measured in Examples 1 and 2 and Comparative Examples 1 and 2 were summarized in Table 1 below. The current density and the maximum power density at 0.4V, which are important characteristics of the actual stack, were compared.

Current density at 0.4 V (mA / ㎠) Power density (mA / ㎠) 30 ℃ 60 ℃ 90 ℃ 30 ℃ 60 ℃ 90 ℃ Example 1 116 328 549 72 140 246 Example 2 86 262 419 62 122 197 Comparative Example 1 50 222 318 55 121 162 Comparative Example 2 44 210 265 40 116 140

As shown in Table 1, Johnson Matthey and E-TEK are commercial catalysts for the low-temperature fuel cell of the present invention including a low-temperature fuel cell catalyst using a fibrous nanocarbon having carbon nanorods as a structural unit as a metal catalyst carrier. The catalyst for low temperature fuel cells, which is superior to the catalyst and manufactured from fibrous nanocarbons having carbon nanorods as structural units, reduces platinum usage from 2 to 1.33 mg / cm 2 and ruthenium from 1 to 0.67 mg / cm 2. It shows superior catalytic activity than commercial catalysts.

1 is a TEM and STM picture of the fibrous nanocarbon having carbon nanorods as basic units, respectively, prepared using pure iron (Fe) catalyst,

FIG. 2 is a graph showing unit cell voltage-current characteristics of a DMFC anode catalyst of 40 wt% Pt / Ru prepared using fibrous nanocarbon having carbon nanorods prepared in Example 1 as a carrier,

3 is a TEM and STM photograph of the fibrous nanocarbon having carbon nanorods as a basic unit prepared using a copper-nickel cocatalyst,

FIG. 4 is a graph showing unit cell voltage-current characteristics of Pt / Ru 40 wt% DMFC anode catalyst prepared using fibrous nanocarbon having carbon nanorods prepared in Example 3 as a carrier,

FIG. 5 is a graph showing DMFC unit cell voltage-current characteristics of Pt / Ru 60 wt% of the commercially available anode catalyst of Comparative Example 1;

FIG. 6 is a graph showing DMFC unit cell voltage-current characteristics of Pt / Ru 60 wt% of the commercially available anode catalyst of Comparative Example 2. FIG.

Claims (15)

In the low-temperature fuel cell catalyst consisting of a carrier and a catalyst, The carrier is a low-temperature fuel cell catalyst, characterized in that the high surface area of the fibrous nanocarbon having a specific surface area of 100m ² / g or more measured by the nitrogen BET method having a nanorod as a basic unit structure. The catalyst for a low temperature fuel cell according to claim 1, wherein the high effective surface area fibrous nanocarbon has a nano rod having a diameter of 2 to 8 nm and a length of 4 to 30 nm as a basic structural unit. The catalyst for a low temperature fuel cell according to claim 1, wherein the specific surface area of the carrier is 100 to 250 m ² / g. The method according to claim 1, wherein the high effective surface area fibrous nanocarbon carrier Iron monocatalyst through oxidation and reduction; Or preparing a transition metal alloy catalyst composed of at least one metal selected from the group consisting of nickel, cobalt, copper and molybdenum; Reducing gas by adding hydrogen gas to the catalyst to generate metal particles on the surface of the catalyst; And A catalyst for a low temperature fuel cell, wherein the catalyst is prepared by adding a saturated gas having 1 to 4 carbon atoms and a mixed gas of carbon monoxide and hydrogen gas. The catalyst for a low temperature fuel cell according to claim 4, wherein the oxidation reaction of the iron single catalyst or the alloy catalyst manufacturing step is performed by injecting air in a temperature range of 350 to 500 ° C. 5. The low temperature of claim 4, wherein the reducing reaction of the iron monocatalyst or the alloy catalyst preparing step is performed by injecting an inert gas containing 5 to 80 vol.% Of hydrogen gas in a temperature range of 400 to 550 ° C. 6. Catalyst for fuel cell. The catalyst for low temperature fuel cells according to claim 4, wherein the metal fine particles have a diameter of 2.5 to 60 nm. The catalyst for a low temperature fuel cell according to claim 4, wherein the reduction reaction of the metal particulate production step is performed for 1 to 30 hours under hydrogen gas. The method of claim 4, wherein the heat treatment is performed by mixing hydrogen gas to a saturated and unsaturated gas having 1 to 4 carbon atoms or a monoxide gas at a ratio of 5 to 80% by volume, and performing at least 1 minute in the range of 350 to 700 ° C. Catalyst for low temperature fuel cell, characterized in that. The method of claim 1, wherein the metal catalyst is a platinum single metal; Or a platinum-alloy catalyst comprising at least one metal selected from the group consisting of ruthenium, palladium, iridium, osmium, rhodium, molybdenum, tungsten, gold, iron and selenium, wherein the high effective surface area fibrous nanocarbon carrier is 5 Catalyst for low temperature fuel cell, characterized in that contained in 95% by weight. 11. The catalyst for low temperature fuel cell according to claim 10, wherein the molar ratio of the platinum-alloy catalyst to other metals mixed with platinum is 1: 0.5 to 1: 2. In the low-temperature fuel cell electrode, An electrode for a low temperature fuel cell comprising a catalyst having a metal catalyst supported on a high effective surface area fibrous nanocarbon carrier having a nano-rod as a basic unit structure. 13. The low temperature fuel cell electrode as claimed in claim 12, wherein the high effective surface area fibrous nanocarbon carrier has a nano rod having a diameter of 2 to 8 nm and a length of 4 to 30 nm as a basic structural unit. In low temperature fuel cell, A low temperature fuel cell comprising a catalyst having a metal catalyst supported on a high effective surface area fibrous nanocarbon carrier having a nano-rod as a basic unit structure as an electrode. 15. The low temperature fuel cell of claim 14, wherein the high effective surface area fibrous nanocarbon carrier has a nano rod having a diameter of 2 to 8 nm and a length of 4 to 30 nm as a basic structural unit.

Images