KR100728611B1 - Catalyst for fuel cell electrode and method of preparing the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode catalyst for a fuel cell and a method of manufacturing the same, and more particularly, to a carbon-based carrier and an electrically conductive polymer at least partially coated with the carbon-based carrier and a transition metal activity distributed on the surface of the electrically conductive polymer. The present invention relates to an electrode catalyst for a fuel cell comprising component particles, and a method for producing the same.

The present invention provides a supported catalyst in which a transition metal active material is supported on a carrier in a high content ratio, and the transition metal active material is dispersed evenly with a high dispersibility. The catalyst activity is very excellent, the manufacturing cost is low, and the carbon monoxide endothelial toxicity is high. There is an effect of providing an electrode catalyst for a fuel cell.

Electroconductive Polymer, Coating, Polypyrrole, Carbonization, Heat Treatment

Description

Electrode catalyst for fuel cell and manufacturing method thereof {Catalyst for fuel cell electrode and method of preparing the same}

1 is a conceptual diagram illustrating a manufacturing process of an electrode catalyst for a fuel cell of the present invention.

2 is a flowchart illustrating a manufacturing procedure of an electrode catalyst for a fuel cell of the present invention.

3A and 3B are transmission electron microscope photographs of the supported catalysts prepared in Examples 1 and 7, respectively.

4 is a graph showing the results of X-ray diffraction analysis performed on the supported catalyst of Example 1. FIG.

5 is a graph showing the results of the performance test performed on the membrane electrode assembly prepared in Example 3, Example 4 and Comparative Example 1.

6 is a graph showing the results of carbon monoxide endothelial toxicity test performed on the membrane electrode assembly prepared in Example 3 and Comparative Example 1.

7 is a graph showing the results of the performance test performed on the membrane electrode assembly prepared in Example 5, Example 6 and Comparative Example 2.

<Explanation of symbols for the main parts of the drawings>

10: conductive polymer monomer 20: transition metal precursor

30: transition metal catalyst particle 30 ': transition metal nuclear growth point

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode catalyst for a fuel cell and a method of manufacturing the same, and more particularly, to an electrode catalyst for a fuel cell and a method for producing the same having excellent catalytic activity, low manufacturing cost and high carbon monoxide endothelial toxicity.

A fuel cell is a device that produces electrical energy by electrochemically reacting fuel and oxygen, and is a power generation device that does not have thermal efficiency as in a Carnot cycle. Fuel cells are more environmentally friendly because they do not emit pollutants such as NOx and SOx, and emit less carbon dioxide and noise than conventional thermal power plants.

Fuel cells can be classified into proton exchange membrane fuel cells (PEMFC), phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), and solids depending on the type of electrolyte used. It is divided into a solid oxide fuel cell (SOFC).

As a fuel cell using a polymer electrolyte membrane that delivers protons, a polymer electrolyte membrane fuel cell (PEMFC) using hydrogen and oxygen as a reactant, and a direct methanol fuel cell (DMFC) using methanol and oxygen as a reactant methanol fuel cell). The polymer electrolyte membrane fuel cell has a relatively low operating temperature and a small volume and weight compared to other fuel cells, and thus may be usefully used for transportation and mobile power.

As a catalyst used in a fuel cell, it is common to use a supported catalyst having a platinum or platinum-ruthenium catalyst supported on a carbon support to increase the utilization of the catalyst. For this purpose, it has recently been generalized to use a material having a large specific surface area and excellent electrical conductivity, such as carbon nanotubes, as a carrier rather than conventional carbon black. However, in order to support the catalyst on the carbon nanotubes in a high content ratio, the Bonnenman method can be applied, but the manufacturing process is complicated and difficult, mass production is difficult. In addition, it is known that it is difficult to prepare a supported catalyst supported by a carbon nanotube in a content of 40 wt% or more by the bulk supported method used as a general catalyst manufacturing method.

On the other hand, as a method of using an electroconductive polymer in a catalyst, Rajeshwar et al. Published a patent for an electrode in which platinum nanoparticles are uniformly dispersed in a polypyrrole film in US Pat. No. 5,334,292, and Finkelshtain et al. In US Pat. No. 6,380,126. A patent for an electrode in which platinum nanoparticles are uniformly dispersed in a polyaniline film has been published. However, these films differ in conductivity depending on the type of dopant, and the like, and in the absence of the dopant, the conductivity is significantly lowered, so that the film cannot be used as a catalyst carrier. In addition, they have a disadvantage in that a large amount of catalyst particles of the noble metal component is distributed inside the polymer film, and thus the manufacturing cost is high compared to the performance. In addition, there is no mention of what these electrodes have in terms of carbon monoxide endothelial toxicity.

The first technical problem to be achieved by the present invention is to provide an electrode catalyst for a fuel cell having excellent catalytic activity, low manufacturing cost, and high carbon monoxide endothelial toxicity.

The second technical problem to be achieved by the present invention is to provide an electrode catalyst for a fuel cell having excellent catalytic activity and electrical conductivity and high carbon monoxide endothelial toxicity.

The third technical problem to be achieved by the present invention is to provide a method for producing an electrode catalyst for a fuel cell having excellent catalytic activity and high carbon monoxide endothelial toxicity.

The fourth technical problem to be achieved by the present invention is to provide an electrode for a fuel cell having excellent catalytic activity and high carbon monoxide endothelial toxicity.

The fifth technical problem to be achieved by the present invention is to provide a membrane electrode assembly for a fuel cell having excellent catalytic activity and high carbon monoxide endothelial toxicity.

The sixth technical problem to be achieved by the present invention is to provide a fuel cell having excellent catalytic activity and high carbon monoxide endothelial toxicity.

The present invention to achieve the first technical problem, a carbon-based carrier;

An electrically conductive polymer at least partially coating the carbonaceous carrier;

Transition metal active ingredient particles distributed on the surface of the electrically conductive polymer; And

Provided is an electrode catalyst for a fuel cell including a catalyst metal precursor or a transition metal active component atom distributed in the electrically conductive polymer.

The present invention to achieve the second technical problem, a carbon-based carrier;

A carbon layer at least partially coating the carbonaceous carrier while forming a separate phase from the carbonaceous carrier;

Transition metal active component particles distributed over the surface of the carbon layer; And

Provided is an electrode catalyst for a fuel cell including a catalyst metal precursor or a transition metal active component atom distributed in the carbon layer.

The present invention to achieve the third technical problem,

(a) providing a mixture of a carbonaceous carrier, a transition metal catalyst precursor, and a conductive polymer monomer dispersed in a dispersion medium;

(b) polymerizing the monomers in the mixture; And

(C) provides a method for producing an electrode catalyst for a fuel cell comprising the step of reducing the catalyst metal precursor.

The fuel cell electrode catalyst manufacturing method is preferably performed at a temperature of about 1 ℃ to about 30 ℃.

The manufacturing method of the electrode catalyst for a fuel cell may further comprise the step of heat-treating the result of step (c).

The present invention provides a fuel cell electrode including the fuel cell electrode catalyst to achieve the fourth technical problem.

The present invention to achieve the fifth technical problem,

A cathode comprising a catalyst layer and a diffusion layer; An anode comprising a catalyst layer and a diffusion layer; And an electrolyte membrane positioned between the cathode and the anode, wherein the cathode or the anode includes an electrode catalyst for a fuel cell of the present invention.

The present invention to achieve the sixth technical problem,

A cathode comprising a catalyst layer and a diffusion layer; An anode comprising a catalyst layer and a diffusion layer; And an electrolyte membrane positioned between the cathode and the anode, wherein the anode or the cathode includes an electrode catalyst for a fuel cell of the present invention.

By using the electrode catalyst for fuel cells of the present invention, it is possible to construct a fuel cell with excellent catalyst activity and high carbon monoxide endothelial toxicity.

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

An electrode catalyst for a fuel cell of a first aspect of the present invention includes a carbon-based carrier; An electrically conductive polymer at least partially coating the carbonaceous carrier; Transition metal active ingredient particles distributed on the surface of the electrically conductive polymer; And a catalytic metal precursor or transition metal active component atom distributed within the electrically conductive polymer.

The carbon-based carrier may be carbon which is widely used as a main component and is generally used as a carrier. For example, graphite, carbon powder, acetylene black, carbon black, activated carbon, mesoporous carbon, carbon nanotube, carbon nanofiber , Carbon nanohorn, carbon nano ring, carbon nanowire, or fullerene (C ₆₀ ), but is not limited thereto.

The electrically conductive polymer may be coated with the carbonaceous carrier as a whole, or may be partially coated. At this time, the coating thickness may be 0.1 nm to 1000 nm, preferably 0.5 nm to 100 nm. If the coating thickness exceeds 1000 nm, there is a disadvantage in that the electrical conductivity is lowered. If the coating thickness is thinner than 0.1 nm, the binding strength with the carbon-based carrier is lowered and it is difficult to dope the transition metal into the electrically conductive polymer.

The electrically conductive polymer is, for example, polypyrrole, polyaniline, polyacetylene, polythioene, polythiophene, polyethylenedioxythiophene, polythienylenevinylene, Polyparaphenylenesulfide (poly (p-phenylenesulfide)) or mixtures thereof, but is not limited thereto.

Examples of the transition metal constituting the transition metal active ingredient particles include platinum (Pt), ruthenium (Ru), iridium (Ir), tungsten (W), cobalt (Co), nickel (Ni), and iron (Fe). ), Osmium (Os), rhodium (Rh), rhenium (Re) or alloys thereof, but is not limited thereto. In particular, the transition metal constituting the transition metal active ingredient particles is preferably platinum or an alloy of platinum and ruthenium.

The average particle diameter of the transition metal active ingredient particles may be about 1 nm to about 500 nm, more preferably about 1 nm to about 10 nm. When the average particle diameter is less than about 1 nm, the catalytic properties of the transition metal are not well expressed, and when the average particle diameter exceeds about 500 nm, the specific surface area is lowered, so that the efficiency is lowered.

The transition metal active ingredient particles are distributed on the surface of the electrically conductive polymer. That is, the electrically conductive polymer is coated on the surface of the carbon-based carrier, wherein the transition metal active ingredient particles are distributed on the outer surface of the electrically conductive polymer. In addition, the catalytic metal precursor or the transition metal active ingredient atom may be distributed in the center of the electrically conductive polymer. This is because the outer surface of the electroconductive polymer is advantageous for mass transfer, and thus it is easy to grow as a transition metal active ingredient particle when the catalyst metal precursor is reduced, whereas the inside of the electroconductive polymer is disadvantageous for material transfer, and thus the transition metal when the catalyst metal precursor is reduced. It is due to the difficulty of growing into active ingredient particles.

An electrode catalyst for a fuel cell of a second aspect of the present invention includes a carbon-based carrier; A carbon layer at least partially coating the carbonaceous carrier while forming a separate phase from the carbonaceous carrier; Transition metal active component particles distributed over the surface of the carbon layer; And a catalytic metal precursor or transition metal active component atom distributed within the carbon layer.

The carbonaceous carrier and the transition metal active ingredient are as described above.

The carbon layer may be a carbon layer generated as a result of carbonization of the polymer, and forms a phase separate from the carbonaceous carrier. The carbon layer may be amorphous or may have a structure having a certain regularity.

The carbon layer may be entirely coated with the carbon-based carrier, or may be partially coated. At this time, the coating thickness may be 0.1 nm to 1000 nm, preferably 0.5 nm to 100 nm. If the coating thickness exceeds 1000 nm, there is a disadvantage in that the electrical conductivity is lowered. If the coating thickness is thinner than 0.1 nm, the binding strength with the carbon-based carrier is lowered and it is difficult to dope the transition metal into the electrically conductive polymer.

The transition metal active ingredient particles are distributed on the surface of the carbon layer. That is, the carbon layer is coated on the surface of the carbon-based carrier, the particles of the transition metal active ingredient is distributed on the outer surface of the carbon layer. In addition, the catalytic metal precursor or transition metal active ingredient atoms may be distributed in the center of the carbon layer. This is because the outer surface of the electrically conductive polymer corresponding to the precursor of the carbon layer is advantageous for material transfer in the preparation of the electrode catalyst for fuel cell, so that it is easy to grow into the transition metal active ingredient particles when the catalyst metal precursor is reduced. The interior is due to the disadvantage of mass transfer and difficult to grow into transition metal active ingredient particles upon reduction of the catalyst metal precursor.

The third aspect of the present invention,

(a) providing a mixture of a carbonaceous carrier, a transition metal catalyst precursor, and a conductive polymer monomer dispersed in a dispersion medium;

(b) polymerizing the monomers in the mixture; And

(C) provides a method for producing an electrode catalyst for a fuel cell comprising the step of reducing the catalyst metal precursor.

The content of the carbon-based carrier is preferably 1% by weight to 60% by weight based on the total weight of the carbon-based carrier, the transition metal catalyst precursor, and the conductive polymer monomer, and the content of the transition metal catalyst precursor is 20% by weight. It is preferably from 90% by weight, and the content of the conductive polymer monomer is preferably 10% by weight to 60% by weight.

If the content of the carbon-based carrier is less than 1% by weight, the supported catalyst is not well formed. If the content of the carbon-based carrier exceeds 60% by weight, the amount of the electrically conductive polymer and the transition metal active ingredient is too high. Less has the disadvantage of poor performance.

When the content of the transition metal catalyst precursor is less than 20% by weight, it is difficult to form a supported catalyst having a high metal content, and when the content of the transition metal catalyst precursor exceeds 90% by weight, the size of the transition metal active ingredient particles produced is There is a disadvantage in that the specific surface area is reduced.

If the content of the conductive polymer monomer is less than 10% by weight, there is a disadvantage that the transition metal active component is not dispersed well, and if the content of the conductive polymer monomer exceeds 60% by weight, the electrical conductivity is relatively lower than that of the carbon-based carrier. Since the content of the electrically conductive polymer increases, there is a disadvantage that the electrical conductivity decreases.

The transition metal catalyst precursor is ionized to be uniformly doped and distributed inside and outside of the electroconductive polymer due to electrostatic interaction with the functional group of the electroconductive polymer. The doped transition metal catalyst precursor ions serve as a nucleation site for the transition metal to grow on the surface of the conductive polymer during the reduction process. Grows into component particles. Therefore, the amount corresponding to the doping level determined according to the amount of the electroconductive polymer in the transition metal catalyst precursor is used for doping, and the amount exceeding the doping level in the transition metal catalyst precursor contributes to the increase in the particle size of the transition metal active ingredient. . In consideration of this point, it is preferable that the concentration of the transition metal catalyst precursor is 1/4 to 2 times the concentration of the conductive polymer monomer. That is, when the concentration of the transition metal catalyst precursor is less than 1/4 times the concentration of the conductive polymer monomer, the growth of the transition metal active component may be insufficient and the catalyst activity may be deteriorated. When the concentration of the conductive polymer monomer is greater than twice the specific surface area of the catalyst particles may be reduced and inefficient.

The transition metal catalyst precursor may be, for example, chloride, nitrate, or sulfate of the transition metal, but is not limited thereto. More specific examples include H ₂ PtCl ₆ , H ₂ IrCl ₆ , IrCl ₃ , PtCl ₂ , RuCl ₃ , RhCl ₃ , NiCl ₂ , and WCl ₆ .

The conductive polymer monomer may be, for example, polypyrrole, polyaniline, polyacetylene, polythiophene, polyethylenedioxythiophene, polythienylenevinylene Polythienylenevinylene), poly (p-phenylenesulfide) or any mixture thereof may be used, and is not particularly limited.

As the dispersion medium, for example, an alcohol-based dispersion medium such as methanol, ethanol or propanol, a nonpolar solvent such as tetrahydrofuran (THF) or acetone, a polar solvent such as benzene or toluene, or water may be used.

Optionally, the mixture may further comprise a surfactant. The surfactant helps the transition metal catalyst precursor and the conductive polymer monomer to be better distributed on the surface of the carbon-based carrier, and may be a nonionic surfactant, a cationic surfactant, an anionic surfactant, and / or an amphoteric surfactant. Can be used. However, in the case of cationic surfactants and anionic surfactants, consideration should be given to the interaction between the transition metal catalyst precursor ions used and the suitability according to the type of dispersion medium. As the amphoteric surfactant, for example, alanine-based, imidazolium betaine-based, aminodipropion salt and the like can be used. As the nonionic surfactant, for example, an alkylaryl polyether alcohol-based compound can be used. It is possible, but not limited to. More specifically, the amphoteric surfactant is preferably Nn-dodecyl-N, N-dimethyl-3-amino-1-propane sulfonate, and the nonionic surfactant is Triton X-100 and Triton X-100. The same material is preferred. The concentration of the surfactant is preferably 2 to 30 times the critical micelle concentration (CMC). The CMC refers to the minimum surfactant concentration at which micelles can be formed.

Optionally, the mixture may further comprise an acid solution. The acid solution is to assist polymerization of the conductive polymer monomer, and may be an inorganic acid such as sulfuric acid, hydrochloric acid, or nitric acid.

The method of mixing the carbon-based carrier, the transition metal catalyst precursor and the conductive polymer monomer to form the mixture is not particularly limited. For example, after dispersing the carbon-based carrier in the dispersion medium, the transition metal catalyst precursor and the conductive It may be to add a polymer monomer. At this time, there is almost no difference depending on the order of introduction of the transition metal catalyst precursor and the conductive polymer monomer.

The transition metal catalyst precursor and the conductive polymer monomer may be stirred at room temperature for about 30 minutes to about 8 hours or mixed for about 20 minutes to about 1 hour using ultrasonic waves.

Following the step of forming the mixture may further comprise the step of adsorbing the transition metal catalyst precursor and the conductive polymer monomer to the carbon-based carrier. The adsorption step may be, for example, using ultrasonic waves, and may be performed for 2 to 6 hours.

The conductive polymer monomer is polymerized with respect to the mixture prepared as described above to coat the surface of the carbonaceous carrier.

An initiator is added to polymerize the conductive polymer monomer. The initiator may use iron chloride (FeCl ₃ ), ammonium persulfate ([NH ₄ ] ₂ S ₂ O ₈ ), sodium persulfate (Na ₂ S ₂ O ₈ ), in particular the electrolysis of the precious metal catalyst prepared ammonium persulfate It is preferred because it does not affect chemical activity.

The concentration of the initiator is preferably 1% to 10% by weight of the amount of the conductive polymer monomer. When the concentration of the initiator is less than 1% by weight of the amount of the conductive polymer monomer, there is a disadvantage that the conductive polymer polymerization is slow, and when the concentration of the initiator exceeds 10% by weight of the amount of the conductive polymer monomer, the conductivity An initiator for preparing a polymer may act as an impurity and reduce the degree of conductive polymer polymerization.

The polymerization temperature is preferably carried out at a temperature of about 1 ° C to about 30 ° C, more preferably at a temperature of about 1 ° C to about 6 ° C. If the polymerization temperature is less than about 1 ℃ reaction rate is too fast to increase the nucleation frequency, thereby increasing the production of oligomers having a small molecular weight, it is not possible to uniformly coat the conductive polymer on the carbon-based carrier. In addition, when the polymerization temperature exceeds about 30 ℃ polymerization reaction is slow may proceed inefficient reaction.

The polymerization time is preferably about 30 minutes to about 4 hours. If the polymerization time is less than about 30 minutes, the reaction may not proceed sufficiently, so that the generation of the electrically conductive polymer may be insufficient. If the polymerization time exceeds about 4 hours, the polymerization may proceed sufficiently and the additional reaction may be insignificant.

After the polymerization of the conductive polymer monomer to form an electrically conductive polymer as described above, it is possible to produce an electrode catalyst for a fuel cell having activity by reducing the catalyst precursor.

A reducing agent may be added directly to reduce the catalyst precursor (first method), or the dispersion medium in the mixture may be removed and reduced while flowing reducing gas in a closed heating space such as an oven or furnace (second method). ).

According to the first method, as the reducing agent, for example, compounds such as sodium borohydride (NaBH ₄ ), methanol, ethanol, formic acid, ethylene glycol and hydrazine may be used. After the addition of the reducing agent may be reduced by stirring at room temperature for 1 hour to 2 hours. However, when a nonionic surfactant is used, it is preferable to avoid alcohol reducing agents.

According to the said 2nd method, it can reduce by heating to 100 degreeC-1000 degreeC, supplying the gas of a reducing atmosphere containing hydrogen to a heating space, for example.

In the electrode catalyst for a fuel cell obtained as described above, for example, impurities such as surfactants and other metal ions may remain, and may be washed and filtered by conventional methods known in the art to remove them. For example, the washing may use a liquid such as deionized water, and may be filtered and dried at a temperature of 60 ° C. or lower.

Optionally, the reduced electrode catalyst for the fuel cell may be annealed to carbonize the electrically conductive polymer. Carbonized electroconductive polymer forms a separate phase from the carbon-based carrier, but has an advantage of improving efficiency because it has a higher electrical conductivity than the electroconductive polymer.

The heat treatment may be performed for about 10 minutes to about 1 hour at a temperature of about 300 ℃ to about 1000 ℃.

When the heat treatment temperature is less than about 300 ℃, the carbonization of the electrically conductive polymer is insufficient to achieve the purpose of heat treatment, and when the heat treatment temperature exceeds about 1000 ℃, the size of the transition metal active ingredient particles is too large to reduce the specific surface area Therefore, there is a fear that the efficiency is lowered.

If the heat treatment time is less than about 10 minutes, the carbonization of the electrically conductive polymer is insufficient, and it is difficult to achieve the purpose of heat treatment. If the heat treatment time exceeds about 1 hour, the size of the transition metal active ingredient particles is too large to reduce the specific surface area. Therefore, there is a fear that the efficiency is lowered.

In this case, the heat treatment may be performed in an inert gas atmosphere such as nitrogen, argon, neon, or helium, or may be performed while alternately forming a hydrogen atmosphere and the inert gas atmosphere to prevent the growth of catalyst particles.

The conceptual diagram and flowchart of the manufacturing method of the electrode catalyst for fuel cells of this invention demonstrated above are shown in FIG. 1 and FIG. 2, respectively. In FIG. 1, the conductive polymer monomer 10 and the transition metal precursor 20 are adsorbed on the surface of the carbon-based carrier, the conductive polymer monomer 10 is polymerized to form an electrically conductive polymer, and the transition metal nucleus growth point is reduced. (30 ') is produced and the transition metal active ingredient is actively grown around the nucleus growth point, particularly on the surface where the material transfer is relatively free, to form the transition metal catalyst particles (30).

Optionally, the transition metal catalyst particles 30 may be subjected to heat treatment after filtration, washing, and drying.

A fourth aspect of the present invention provides an electrode for a fuel cell comprising the electrode catalyst for fuel cell.

The electrode may be prepared by a method well known in the art, and is not particularly limited. For example, non-limiting examples of the electrode can be prepared by dispersing a powder and a binder of an electrode catalyst for fuel cell in a solvent, and applying it to a porous, preferably diffusion layer, followed by drying.

A fifth aspect of the present invention provides a membrane electrode assembly including the electrode catalyst for fuel cell.

The present invention provides a cathode comprising a catalyst layer and a diffusion layer; An anode comprising a catalyst layer and a diffusion layer; And an electrolyte membrane positioned between the cathode and the anode, wherein the cathode or the anode includes an electrode catalyst for a fuel cell of the present invention.

The diffusion layer and the electrolyte membrane included in the cathode and the anode may be well known in the fuel cell art. In addition, the catalyst layer of the cathode and / or the anode includes the electrode catalyst for a fuel cell of the present invention.

A sixth aspect of the present invention provides a fuel cell comprising the electrode catalyst for fuel cell.

The present invention provides a cathode comprising a catalyst layer and a diffusion layer; An anode comprising a catalyst layer and a diffusion layer; And an electrolyte membrane positioned between the cathode and the anode, wherein the anode or the cathode includes an electrode catalyst for a fuel cell of the present invention.

The diffusion layer and the electrolyte membrane included in the cathode and the anode may be well known in the fuel cell art. In addition, the catalyst layer of the cathode and / or the anode includes the electrode catalyst for a fuel cell of the present invention.

In the production of such a fuel cell, since a conventional method known in various documents can be used, detailed description thereof is omitted here.

Hereinafter, the structure and effects of the present invention will be described in more detail with specific examples and comparative examples, but these examples are only intended to more clearly understand the present invention and are not intended to limit the scope of the present invention.

Example 1 Preparation of Supported Catalyst Having Electroconductive Polymer Layer

By connecting the cooling circulation tank to the double tube reactor to circulate the cooling water to maintain the temperature of the reactor at 5 ℃ for the whole process. To 0.1 g of carbon nanotubes (manufactured by ILJIN Nanotech Co., Ltd.), 30 mL of Triton X-100 (manufactured by Aldrich), a surfactant, was added at a concentration of 20 mM and sufficiently stirred. 10 mL of 0.25 M pyrrole aqueous solution (produced by Aldrich) was added thereto, followed by sufficient stirring, and 10 mL of 0.1 M aqueous platinum chloride solution was added thereto, followed by sufficient stirring. As an initiator, 1 mL of 0.5 M ammonium peroxide sulfate was added thereto, followed by polymerization for 1 hour, and then an aqueous solution of sodium borohydride at 1 M concentration was added to reduce the platinum catalyst. After washing, filtering and drying with deionized water, 0.64 g of a weakly supported catalyst having a platinum-polypyrrole complex applied to carbon nanotubes was obtained. Thermogravimetric analysis (TGA) analysis showed that the supported catalyst had a platinum content of 61% by weight.

3A shows a surface photograph taken using a transmission electron microscope (TEM) for the supported catalyst. As can be seen in Figure 3a it can be seen that the catalyst metal having a size of about 3 nm or less is uniformly dispersed and supported.

The X-ray diffraction (XRD) spectrum of the supported catalyst is observed in FIG. 4. As can be seen in Figure 4, it can be confirmed that the conductive polymer is polymerized on the surface of the carbon nanotubes by disappearing the crystalline peak of the carbon nanotubes appearing at 2θ around 25 degrees, through a peak near 40 degrees It can be seen that platinum crystalline particles are produced.

Example 2 Preparation of Supported Catalyst Carbonized with Electroconductive Polymer

The supported catalyst prepared in Example 1 was heat-treated in an argon gas atmosphere for 30 minutes in a tube furnace at 350 ° C. to prepare a supported catalyst having a platinum content of about 78%.

<Example 3> Preparation of a membrane electrode assembly (MEA) using the supported catalyst of Example 1

The supported catalyst prepared in Example 1 was applied to the anode gas diffusion layer so that the amount of Pt supported was 0.1 mg / cm ² . In addition, a commercial Pt / C catalyst (manufactured by E-TEK, HP 60 wt% Pt / C) was applied to the cathode gas diffusion layer so that the amount of Pt supported was 1 mg / cm ² . As the gas diffusion layer, commercially available carbon paper (SGL-10BC, manufactured by SGL) was used for both the anode and the cathode. Pt / C and Nafion (Dupont, SE5012) solutions were added to a mixed solvent of isopropyl alcohol and water (mixing ratio 1: 1), and then dispersed in an ultrasonic bath for about 10 minutes or longer. Thus obtained catalyst ink was applied to the gas diffusion layer by spray coating, followed by drying to prepare a cathode and an anode. At this time, the Nafion content of the dried catalyst layer was 15% by weight for the anode and 10% by weight for the cathode.

Nafion 117 (manufactured by Dupont) was used as the polymer electrolyte membrane.

After inserting the polymer electrolyte membrane between the anode and the cathode, a pressure of about 1 ton was applied at a temperature of about 135 ° C. for about 3 minutes to prepare a membrane electrode assembly.

<Example 4> Preparation of MEA using the supported catalyst of Example 2

A membrane electrode assembly was prepared in the same manner as in Example 3, except that the supported catalyst prepared in Example 2 was used instead of the supported catalyst prepared in Example 1.

Comparative Example 1 Preparation of MEA Using Commercial Pt / C Catalyst

A membrane electrode assembly was manufactured in the same manner as in Example 3, except that a commercial Pt / C catalyst (manufactured by E-TEK) was used instead of the catalyst prepared in Example 1.

<Evaluation Example 1>

The performance of the membrane electrode assembly prepared in Example 3, Example 4 and Comparative Example 1 was measured. The anode was supplied with humidified 99.9% hydrogen and the cathode was supplied with humidified 99.9% oxygen. The change of the battery voltage according to the current density at the operating temperature of 50 ℃ was measured and the results are shown in FIG.

As shown in FIG. 5, although the supported amount of the platinum catalyst of Examples 3 and 4 was only one tenth of that of Comparative Example 1, Examples 3 and 4 were superior to Comparative Example 1, respectively. This is presumably due to the increased catalyst utilization due to the small and uniformly dispersed catalyst particles.

Evaluation Example 2 Carbon Monoxide Endothelial Toxicity Evaluation

Carbon monoxide endothelial toxicity was tested for the membrane electrode assembly prepared in Example 3 and Comparative Example 1. The evaluation was carried out in the same manner as in Evaluation Example 1, except that hydrogen containing 100 ppm of carbon monoxide was humidified and supplied as the anode fuel, and the results are shown in FIG. 6.

In addition, the results of the evaluation example 1 performed for Example 3 are compared with FIG. 6 to compare the degree of deterioration in comparison with the case where there is no carbon monoxide (Example 3a).

As shown in FIG. 6, the performance of the fuel containing carbon monoxide is lower than that of the fuel without carbon monoxide, but the performance of Example 3 is far superior to carbon monoxide toxicity compared to Comparative Example 1. It can be seen that. This means that it can be suitably employed as a catalyst of a fuel cell fueled by a reformed hydrogen enriched gas. The principle of endothelial carbon monoxide toxicity has not been elucidated. However, in view of the fact that the catalyst loading of Example 3 is only one tenth of the catalyst loading of Comparative Example 1, the endothelial toxicity to carbon monoxide is dramatically reduced. It can be seen that the improvement.

Example 5 Preparation of PtRu Supported Catalyst Having Electroconductive Polymer Layer

The supported catalyst was prepared in the same manner as in Example 1, except that 10 mL of an aqueous solution of chloroplatinic acid at a concentration of 0.1 M was added, and 5 mL of an aqueous solution of chloroplatinic acid at a concentration of 0.133 M and 5 mL of ruthenium chloride, respectively. Got it.

<Example 6> Preparation of MEA using the supported catalyst of Example 5

Membrane electrode assembly in the same manner as in Example 3, except that the supported catalyst prepared in Example 5 was applied to the anode gas diffusion layer so that the coating amount of 1.0 mg / cm ² was applied instead of the supported catalyst prepared in Example 1. Was prepared.

Comparative Example 2 Preparation of MEA Using Commercial PtRu Catalyst

A membrane electrode was applied in the same manner as in Example 3 except that a commercial PtRu catalyst (manufactured by E-TEK) was applied to the anode gas diffusion layer so that the coating amount was 4.0 mg / cm ² instead of the supported catalyst prepared in Example 1. The conjugate was prepared.

<Evaluation Example 3>

The performance was evaluated about the membrane electrode assembly prepared in Example 6 and Comparative Example 2. A 2 M aqueous solution of methanol was supplied to the anode and dry air was supplied to the cathode. The change of the battery voltage according to the current density at the operating temperature of 50 ℃ was measured and the results are shown in FIG.

As shown in FIG. 7, it can be seen that the catalyst loading in Example 6 has almost the same performance as the catalyst loading in Comparative Example 2, even though it is a quarter level. This means that the electrode catalyst for a fuel cell of the present invention has a very good performance in methanol oxidation characteristics.

<Example 7>

The supported catalyst was prepared in the same manner as in Example 1 except that the amount of the aqueous platinum chloride solution at a concentration of 0.1 M was increased to 30 mL.

TGA analysis showed that the supported catalyst had a platinum content of 78% by weight. In addition, the surface photograph taken using the TEM for the supported catalyst is shown in Fig. 3b. As can be seen in Figure 3b it can be seen that the catalyst metal having a size of about 3 nm or less is uniformly dispersed and supported.

Although described in detail with respect to preferred embodiments of the present invention as described above, those of ordinary skill in the art, without departing from the spirit and scope of the invention as defined in the appended claims Various modifications may be made to the invention. Therefore, changes in the future embodiments of the present invention will not be able to escape the technology of the present invention.

The present invention provides a supported catalyst in which a high amount of transition metal active material is supported on a carrier, and the transition metal active material is evenly dispersed with a high dispersibility, so that the catalyst activity is very excellent, the manufacturing cost is low, and the carbon monoxide endothelial toxicity is high. There is an effect of providing an electrode catalyst for a fuel cell.

Claims (21)

Carbon-based carriers; An electrically conductive polymer coating all or part of the surface of the carbonaceous carrier; Transition metal active ingredient particles distributed on the surface of the electrically conductive polymer; And An electrode catalyst for a fuel cell comprising a chloride, nitride, or sulfur oxide of a transition metal or a transition metal active component atom distributed in an interior of the electrically conductive polymer. The method of claim 1, wherein the electrically conductive polymer is polypyrrole, polyaniline, polythiophene, polyethylenedioxythiophene, polythienylenevinylene, polyparaphenylene sulfide (poly (p-phenylenesulfide)) or an electrode catalyst for a fuel cell, characterized in that a mixture thereof. The electrode catalyst for a fuel cell according to claim 1, wherein the thickness of the electrically conductive polymer is 0.1 nm to 1000 nm. The electrode catalyst for a fuel cell according to claim 1, wherein the thickness of the electrically conductive polymer is 0.5 nm to 100 nm. The method of claim 1, wherein the transition metal active ingredient is platinum (Pt), ruthenium (Ru), iridium (Ir), tungsten (W), cobalt (Co), nickel (Ni), iron (Fe), osmium (Os) ), Rhodium (Rh), rhenium (Re) or an alloy thereof. The electrode catalyst for fuel cell according to claim 1, wherein the average particle diameter of the transition metal active ingredient particles is 1 nm to 500 nm. The method of claim 1, wherein the carbon-based carrier is graphite, carbon powder, acetylene black, carbon black, activated carbon, mesoporous carbon, carbon nanotubes, carbon nanofibers, carbon nanohorns, carbon nano rings, carbon nanowires, or Fullerene (C ₆₀ ) electrode catalyst for fuel cells, characterized in that. Carbon-based carriers; A carbon layer forming a phase separate from the carbonaceous carrier and coating all or part of the surface of the carbonaceous carrier; Transition metal active component particles distributed over the surface of the carbon layer; And An electrode catalyst for a fuel cell comprising a chloride, nitride, or sulfur oxide of a transition metal distributed within the carbon layer, or a transition metal active component atom. (a) providing a mixture of a carbonaceous carrier, a chloride, a nitride, or a sulfur oxide of a transition metal, and a conductive polymer monomer dispersed in a dispersion medium; (b) polymerizing the monomers in the mixture; And (C) a method for producing an electrode catalyst for a fuel cell comprising the step of reducing the chloride, nitride, or sulfur oxide of the transition metal. 10. The method according to claim 9, wherein the carbon-based carrier, the chloride, nitride, or sulfur oxide of the transition metal, and the content of the carbon-based carrier 1% to 60% by weight based on the total weight of the conductive polymer monomer, the transition metal The method of producing an electrode catalyst for a fuel cell, characterized in that the content of chloride, nitride, or sulfur oxide of 20% to 90% by weight, the content of the conductive polymer monomer is 10% to 60% by weight. The method of claim 9, wherein the concentration of the chloride, nitride, or sulfur oxide of the transition metal is 1/4 to 2 times the concentration of the conductive polymer monomer. 10. The method of claim 9, wherein the polymerization is performed at a temperature of 1 ° C to 30 ° C. 10. The method of claim 9, wherein the polymerization is performed at a temperature of 1 ° C to 6 ° C. 10. The method of claim 9, wherein the mixture of step (a) further comprises a surfactant. The method for producing an electrode catalyst for a fuel cell according to claim 14, wherein the surfactant is an alanine-based, imidazolium betaine-based, aminodipropion salt or alkylaryl polyether alcohol-based compound. 10. The method of claim 9, wherein the reducing of the step (c) is performed at a temperature of 100 ° C to 1000 ° C in a hydrogen atmosphere. 10. The method of claim 9, further comprising the step of heat-treating the resultant of step (c). 18. The method of claim 17, wherein the heat treatment is performed at a temperature of 300 ° C to 1000 ° C. A fuel cell electrode comprising the electrode catalyst for fuel cell according to any one of claims 1 to 8. A cathode comprising a catalyst layer and a diffusion layer; An anode comprising a catalyst layer and a diffusion layer; And an electrolyte membrane positioned between the cathode and the anode, wherein the cathode or anode comprises an electrode catalyst for a fuel cell according to any one of claims 1 to 8. Electrode assembly. A cathode comprising a catalyst layer and a diffusion layer; An anode comprising a catalyst layer and a diffusion layer; And an electrolyte membrane positioned between the cathode and the anode, wherein the anode or cathode comprises an electrode catalyst for a fuel cell according to any one of claims 1 to 8. .

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