KR20100011029A - Hcms carbon-supported electrode catalysts in proton exchange membrane fuel cell and method for manufacturing the same - Google Patents

Abstract

PURPOSE: An HCMS(hollow core with mesoporous shell) carbon-supported electrode catalyst is provided to improve the performance of a fuel cell due to high catalyst activity compared with Pt-Ru catalyst and Pt catalyst dipped in the existing carbon black. CONSTITUTION: An HCMS(hollow core with mesoporous shell) carbon-supported electrode catalyst comprises 15~84 weight% of a hollow core with mesoporous shell consisting of an inside having macro hollow and an outer surface having mesopore; 15~80 weight% transition metal; and 0.01-5 weight% at least one or two kinds selected from a polyalkylene oxide copolymer and alkyl polyethylene oxide copolymer.

Description

HCC carbon-supported catalyst for fuel cell electrode and method for manufacturing same {HCC carbon-supported electrode catalysts in proton exchange membrane fuel cell and method for manufacturing the same}

The present invention uses a carbon capsule structure of a hollow core with mesoporous shell (HCMS) structure as a carrier, and has a structure in which a catalyst metal is supported thereon. It relates to a HCMS carbon supported catalyst and a preparation method thereof.

Unlike ordinary batteries, fuel cells do not need to be replaced or recharged. Instead, a fuel cell is a device that converts chemical energy into electrical energy through an electrochemical reaction by supplying fuel such as hydrogen or methanol. The advantages of fuel cell are high efficiency (less than about 60% of energy conversion efficiency), and it is possible to use various fuels as a pollution-free energy source, and it has advantages such as small area area and short construction period. Various applications are possible, from decentralized power generation to utility power, residential and power projects. The potential market size is expected to be enormous, especially when the operation of fuel cell vehicles, the next generation transportation device, is used in various ways. In particular, hydrogen fuel proton exchange membrane (PEM) fuel cells have attracted attention as energy sources for automobiles and transportation that require greater power.

The principle of the PEM fuel cell is as follows. The fuel cell includes a fuel electrode (oxide electrode), an oxygen electrode (reduction electrode), and a proton exchange membrane that physically separates them. Hydrogen is supplied to the fuel electrode and oxygen is supplied to the oxygen electrode. When a wire is connected to each of the fuel electrode and the oxygen electrode (for example, by connecting an external power consumption circuit), the circuit starts operation.

In the fuel electrode, the supplied hydrogen is decomposed into protons and electrons as shown in Formula 1, and the protons are easily transferred from the fuel electrode to the oxygen electrode through the membrane, whereas the polymer electrolyte membrane, which is an electrical insulator, is transferred from the anode to the oxygen electrode through the membrane. Block it from becoming

H ₂ → 2H ^{+ +} 2e ^-

Accordingly, in the oxygen electrode, the supplied oxygen is reduced as shown in the following formula (2).

_{^{O 2 + 4H + + 4e -}} → 2H 2 O

Therefore, when the operation of the fuel cell is combined, the hydrogen supplied to the anode as the cathode combines with the oxygen supplied to the oxygen as the anode to generate water and electrical energy. In order to improve the function and efficiency of the PEM fuel cell, it is important to use a highly active catalyst material, but it is also very important to improve the characteristics of the electrode. That is, it is also important to improve the diffusivity of the hydrogen gas and oxygen gas used in the electrode reaction in the electrode, and to increase the conductivity of the hydrogen ions and electrons generated by the electrode reaction. On the other hand, the catalyst is usually supported on a carrier, and in general, carbon having a nano-sized pore structure is used as the carrier. Accordingly, the electrode of the hydrogen gas and the oxygen gas has a porous structure in which a catalyst supported carbon carrier and a polymer electrolyte are combined, and a carrier having a large pore volume with a large surface area in order to optimize the size and dispersion of the catalyst nanoparticles. It is preferable to use. The carbon carrier is an electron conduction channel and the polymer electrolyte is a hydrogen ion conduction channel.

Porous pores of the electrode play an important role as supply and discharge channels for oxygen gas, hydrogen gas and water. Therefore, the improvement of the microstructure and manufacturing method of the electrode, the amount of the polymer electrolyte in the electrode is an important factor for improving the characteristics. With regard to the microstructure of the electrode described above, the catalytic activity is greatly changed because the size, stability, and dispersion state of the catalyst nanoparticles supported depend on the properties and the microstructure of the carbon carrier. In addition, the characteristics of the fuel cell are greatly changed because the reaction and the movement and discharge of the product, the conductivity of hydrogen ions and electrons change depending on the structure of the carbon carrier as the electrode carrier such as pore distribution and connectivity, surface area and surface properties. In general, when the surface area and pore volume of the carbon carrier are large, the size of the supported metal catalyst particles is smaller and more uniformly distributed on the carbon carrier to increase the active area, and the diffusion of fuel and reaction products can easily occur, thereby improving the activity. Can be. However, if the average particle diameter of the carbon material constituting the carbon carrier is large or the size of the internal pores of the carbon carrier is large, the specific surface area of the carbon carrier decreases, so that the amount of catalyst material carried thereon decreases and the dispersion state decreases. The characteristics of the battery tend to be deteriorated. When the average particle diameter and pore size of the carbon materials constituting the carbon carrier are extremely small, the specific surface area becomes very high, so that the amount of supported catalyst material increases, but delivery and diffusion of the reaction gas, etc. It becomes difficult and the polymer electrolyte cannot penetrate into the micropore, so that the utilization efficiency of the catalyst is lowered and the fuel cell characteristics are not improved.

Therefore, optimizing the structure and shape of the carbon carrier is a method of maximizing the performance and efficiency of a fuel cell, particularly a proton electrolyte membrane (PEM) fuel cell.

However, until now, little correlation has been examined between the microstructure of the electrode carbon carrier for fuel cells and the characteristics of the fuel cell. For this reason, fuel cells using various carbon materials, including activated carbon, have been manufactured and their characteristics have been examined, but the optimum characteristics have not yet been obtained.

Electrocatalysts currently used for the oxidation and reduction of fuel and air in fuel cells have good electrical conductivity and are relatively large in surface area, for example carbon black having a surface area of about 230 m ² / g, for example Vulcan from Cabot It is prepared by dispersing a metal catalyst in the form of fine particles using XC-72 as a carrier. However, since the Vulcan XC-72 has a non-uniform pore size distribution, and particularly contains a large number of micropores that the polymer electrolyte cannot reach well, the catalyst particles supported thereon do not form a three-phase interface and thus do not contribute to the electrochemical reaction. In addition, Vulcan XC-72 has a problem of limiting the activity of the supported catalyst by preventing the diffusion of gas due to the lack of three-dimensional pore connectivity. For this reason, the development of a new high-efficiency carrier is required, and there are several characteristics required for catalysts for fuel cell electrodes such as Pt-Ru / C and Pt / C in connection with the improvement of the activity of the fuel cell.

First, the metal catalyst particles should be small in size and uniformly dispersed to provide a wide range of catalytic active sites and have a large surface area where oxidation and reduction reactions occur.

Second, the carbon used as a carrier should have a large surface area and a well-developed porous structure to facilitate the movement of gas and water, and the metal catalyst particles should be strongly supported so that the metal catalyst particles cannot be separated by physical and chemical impacts.

As such, the carrier used for electrode production of a fuel cell is required to have a suitable porosity, excellent electrical conductivity, and a large surface area. In the case of a catalyst for a fuel cell electrode, carbon black has been used as a carrier for a catalyst.

The inventors of the present invention disclose a method for producing porous carbon molecular sieves having a uniform size and regularity using a liquid carbon precursor, which is a method for producing porous carbon having excellent electrical conductivity and having uniform pores and a large surface area. 0369979, "A catalyst for a fuel cell using a porous carbon structure in which spherical pores having a uniform diameter are regularly arranged in three dimensions, and a method of manufacturing the same" is described in Korean Patent No. 10-0574030, "Hollow with a mesoporous outer shell. The method of manufacturing a nanocapsule structure has already been registered as Korean Patent No. 10-0500975, and is a fuel cell electrode supported by HCMS carbon capsule structure for a direct methanol fuel cell using methanol as a fuel. "Method for preparing catalyst and electrocatalyst" has already been registered as Korean Patent No. 10-0544886, and their description For forms a part of the content of this is their entireties by reference to the context of the present invention Reference.

Accordingly, the present inventors have attempted to solve the above problems, the catalyst particles supported on the carrier used in the prior art does not form a three-phase interface, the connectivity of the carrier pores is small, preventing the diffusion of gas to limit the activity of the supported catalyst In addition to solving the above problem, the metal catalyst is uniformly dispersed in the carrier to provide a wide range of catalytic active sites, thereby completing the HCMS carbon supported catalyst for fuel cell electrodes that can maximize the activity. It is an object of the present invention to provide a HCMS carbon supported catalyst for fuel cell electrodes and a method of manufacturing the same.

HCMS carbon supported catalyst for fuel cell electrode of the present invention for solving the above problems is 1) spherical carbon capsule structure of the hollow core (Hollow core with mesoporous shell) structure; 2) transition metals; And 3) a single or two types of copolymers selected from polyalkylene oxide copolymers and alkylpolyethylene oxide copolymers.

In addition, the present invention relates to a method for producing the HCMS carbon supported catalyst for the fuel cell electrode,

An underwater slurry of a spherical carbon capsule structure having a hollow core structure; An aqueous solution in which a water-soluble metal salt having catalytic activity is dissolved; And a single or two types of copolymers selected from a polyalkylene oxide copolymer and an alkyl polyethylene oxide copolymer; a first step of preparing a mixed solution by mixing;

A second step of diluting and stirring distilled water into the mixed solution such that the concentration of the water-soluble metal salt is 1 mM to 5 mM;

A third step of preparing a reaction solution by adjusting the pH of the diluted mixed solution to 8-9;

A fourth step of preparing a catalyst by adding a reducing agent to the reaction solution to reduce the water-soluble metal salt to form metal particles, and then supporting the formed metal particles on the carbon capsule structure; And

And a fifth step of separating the catalyst from the reaction solution.

HCMS carbon supported catalyst for fuel cell electrode according to the present invention has the advantage that the supported catalyst can be produced while using a smaller amount than carbon black by using a carbon capsule structure of a porous hollow core structure having excellent electrical conductivity and a large surface area In this case, metal particles of very small sizes of 1 to 4 nm, preferably 2 to 3 nm can be uniformly dispersed in the structure, thereby increasing the active area where a catalytic reaction can occur, and thus, with a fuel such as hydrogen. There is an effect that can increase the catalytic activity for the oxidation reaction and the reduction reaction of oxygen.

In addition, since the HCMS carbon supported catalyst for fuel cell electrode of the present invention has higher catalytic activity than the Pt-Ru catalyst or Pt catalyst supported on the existing carbon black, the performance of the fuel cell can be improved, and the solution is simple in aqueous state. There is an advantage that can be produced by the method.

This invention will be described in detail.

The present invention relates to a HCMS carbon supported catalyst for fuel cell electrodes, characterized in that it comprises a spherical carbon capsule structure having a hollow core with mesoporous shell structure and a transition metal,

More specifically,

The HCMS carbon supported catalyst for fuel cell electrodes of the present invention further includes a single or two types of copolymers selected from polyalkylene oxide copolymers and alkyl polyethylene oxide copolymers.

The spherical carbon capsule structure (hereinafter referred to as "HCMS carbon capsule structure") of the hollow core with a mesoporous shell structure is composed of a double structure of an outer shell having an inner and a mesopores having a macro hollow, The manufacturing method is described in detail in Korean Patent Registration No. 10-0500975 as mentioned above.

Briefly summarized the manufacturing method of the carbon capsule structure is as follows. First, uniformly sized spherical silica particles are synthesized through sol-gel process, and then the silica mesoporous outer shell is formed on the surface of the synthesized silica, and the shell is filled with intermediate pores. with mesoporous shell) After synthesis, the polymer precursor is injected into mesoporous outer mesopores, and if the precursor is a monomer, the polymer precursor is molded through polymerization, and then polymerized to obtain a polymer-silica template composite, and then the polymer-silica composite is inactivated. The carbonization process is carried out at temperatures of 900 ° C. to 1000 ° C. under gas to give a composite of carbon-silica. Selective dissolution of the silica template using a hydrofluoric acid (HF) solution or sodium hydroxide (NaOH) solution results in the formation of pores of a certain size in the place where the silica template is melted. It has pores and the outer shell produces spherical new HCMS carbon capsule structures with mesopores formed. In this case, the mesopores may be regularly or irregularly distributed according to the synthesis method. In addition to the patent document, the inner hollow diameter of the carbon capsule structure can be variously adjusted by controlling the size of the silica particles, the thickness of the outer shell is selected from C ₁₈ -TMS (octadecyltrimethoxysilane) and HTMABr (hexadecyltrimethylammonium bromide) or 2 It is possible to control the outer thickness by controlling the amount of the surfactant consisting of more than one species and silica tetraethoxysilane (TEOS), that is, by adjusting the TEOS / surfactant molar ratio. The regularity of the distribution of mesopores in the outer shell can also be adjusted as follows. In the case of C ₁₈ -TMS and TEOS, the hydrolysis reaction of the two compounds is carried out simultaneously and disordered mesopores are formed in the silica shell. On the other hand, in the case of HTMABr and TEOS, since HTMABr first forms a regular micelle structure on the silica wall, TEOS is hydrolyzed and polymerized thereon to form regular mesopores. On the other hand, as the carbon precursor used to form the outer shell having mesopores, the present invention is not limited thereto, but divinylbenzene (DVB), acrylonitrile, phenol, phenolic resin, Sugars and general formula, including vinyl chloride, vinyl acetate, styrene, methacrylate, methyl methacrylate, ethylene glycol dimethacrylate, furfuryl alcohol, resorcinol-formaldehyde (RF), and Compounds represented by CH ₂ = CRR '(where R and R' are alkyl or aryl groups) or those which form graphitic carbon by a carbonation reaction selected from mesophase pitch are used. Included.

As a radical polymerization initiator used for superposition | polymerization of the said polymer monomer, although this invention is not limited to this, azobisisobutyronitrile (AIBN), t-butylperacetate, benzoyl peroxide, acetyl peroxide, and lauryl It can select from the initiators used for normal radical polymerization reactions, such as a peroxide, and can use.

Matters related to the manufacturing method of the HCMS carbon capsule structure other than the above are described in detail in Korean Patent Registration No. 10-0500975, and also, the type of the carbon precursor and SCMS silica specified above to control the shape of the mesoporous shell. By varying the ratio of the template particles and the carbon precursor, it can be synthesized in various ways from the rough surface to the smooth surface to maximize the function as a catalyst carrier.

The HCMS carbon capsule structure, which is one of the components of the HCMS carbon supported catalyst for fuel cell electrodes of the present invention, serves as a carrier to a support of metal particles in the present invention, wherein the spherical carbon capsule structure of the hollow core structure is 30 nm. Above, preferably having a macro hollow core having a constant internal diameter of 30 nm to 1000 nm, the outer shell in the middle of a uniform diameter in the range of 2 nm to 20 nm, more preferably 2 nm to 10 nm It is a spherical carbon capsule with a double pore structure with pores. The spherical carbon capsule structure of the hollow core structure can be used as a catalyst itself, and can be applied to various applications such as adsorbents, separation and purification, hydrogen and drug storage, and electrodes. Herein, when the inner diameter of the spherical carbon capsule structure of the hollow core structure is less than 30 nm, it may be difficult to form a spherical capsule having a uniform shape, and when the thickness exceeds 1000 nm, a problem may occur in that the activity decreases due to a decrease in surface area. If possible, it is better to use the above range. In addition, when the pores of the outer shell of the spherical carbon capsule structure of the hollow core structure is less than 2 nm, the material is difficult to move, the three-phase interfacial formation is difficult, and the activity may decrease, and when the surface area exceeds 20 nm, the surface area may be reduced. It is preferable to use one within the above range because a problem of decrease in activity may occur.

One of the components of the present invention is the transition metal is platinum (Pt), ruthenium (Ru), rhodium (Rh), molybdenum (Mo), osmium (Os), iridium (Ir), rhenium (Re), palladium (Pd) , Vanadium (V), tungsten (W), cobalt (Co), iron (Fe), selenium (Se), nickel (Ni), bismuth (Bi), tin (Sn), Cr (chromium) and copper (Cu It includes single or two or more metals selected from among others. When using two or more kinds of the transition metal, it is not particularly limited, but it is preferable to use a composite metal containing two or more kinds selected from platinum, ruthenium or molybdenum. In this case, when the platinum-ruthenium (Pt-Ru) composite metal is used as the transition metal, it is preferable to use a platinum-ruthenium transition metal having a molar ratio of 1: 0.5 to 1.5 of platinum and ruthenium. In this case, if the ruthenium is less than 0.5 mole with respect to 1 mole of the platinum, there may be a problem that the activity decreases, and even if more than 1.5 moles may cause a problem that the catalytic activity decreases, it is preferable to use within the molar ratio range. .

The transition metal in the preparation of the catalyst of the present invention is a water-soluble metal salt of the spherical carbon capsule structure of the hollow core structure; And a copolymer selected from the group consisting of one or two selected from a polyalkylene oxide copolymer and an alkyl polyethylene oxide copolymer. The water-soluble metal salt is converted into metal particles and supported on the carbon capsule structure.

The polyalkylene oxide copolymer or alkylpolyethylene oxide copolymer, which is one of the other components of the present invention, in the present invention, the transition metal is uniformly well dispersed in the HCMS carbon capsule structure and the size of the transition metal The polyalkylene oxide copolymer is used to control the average molecular weight of 100 to 8000, more preferably 300 to 3500, the average molecular weight of the polyalkylene oxide copolymer is 100 If less than, the micelle (micelle) of the polyalkylene oxide copolymer is small to form a small metal catalyst, but the problem that can be agglomerated from the outside in most cases, the average molecular weight of more than 8000 polyalkylene oxide copolymer micelle itself is too large This is because a problem that the size of the metal catalyst is large may occur.

In addition, the polyalkylene oxide copolymer is a poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) triple copolymer [poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) triblock copolymer , Hereinafter referred to as "EO-PPO-PEO". In particular, in the case of using PEO-PPO-PEO in the polyalkylene oxide copolymer, Pluronic L31 (average molecular weight = 110), Pluronic L35 [(EO) ₁₁ (PO) ₁₆ (EO) ₁₁ , Average molecular weight = 1900], Pluronic L42 (average molecular weight = 2200), Pluronic L61 [(EO) ₂ (PO) ₃₀ (EO) ₂ ], L62 (average molecular weight = 2500), Pluronic 62D (average molecular weight = 2360), Pluronic L62LF (average molecular weight 2450), Pluronic L63 (average molecular weight = 2650), Pluronic L64 [(EO) ₁₃ (PO) ₃₀ (EO) ₁₃ , average molecular weight = 2900], Pluronic L65 [(EO) ₁₉ (PO) ₃₀ ( EO) ₁₉ , average molecular weight = 3400)], Pluronic L72 (average molecular weight = 2750) and Pluronic L92 (average molecular weight = 3650), it is preferable to use one or two or more selected.

In the case of using an alkyl polyethylene oxide copolymer, one or two selected from Brij 52 [C ₁₆ (EO) ₂ ], Brij 56 [C ₁₆ (EO) ₁₀ ] and Brij 58 [C ₁₆ (EO) ₂₀ ] It is good to mix and use the above.

HCMS carbon supported catalyst for fuel cell electrode of the present invention

Hollow core with mesoporous shell (HCMS) carbon capsule structure; and transition metal; And a single or two types of copolymers selected from polyalkylene oxide copolymers and alkyl polyethylene oxide copolymers.

Hollow core with mesoporous shell (HCMS) carbon capsule structure 15-84 wt%;

Transition metal 15 to 80% by weight; And

0.01 to 5% by weight of one or two types of copolymers selected from polyalkylene oxide copolymers and alkyl polyethylene oxide copolymers.

Here, the HCMS carbon capsule structure may use 15 to 84% by weight, more preferably 20 to 80% by weight based on the total weight of the HCMS carbon supported catalyst for fuel cell electrodes, wherein the amount of the structure used is 15% by weight If it is less than the active metal nanoparticle size may tend to increase, if the 84% by weight thickening catalyst layer may interfere with the diffusion of the material may occur, the transition metal is HCMS carbon support for fuel cell electrode of the present invention It is characterized in that it comprises 15 to 80% by weight more preferably 50 to 80% by weight based on the total weight of the catalyst, when less than 15% by weight thickening the catalyst layer may interfere with the diffusion of materials This is because the size of the active metal nanoparticles may increase when the amount exceeds 80% by weight, thereby decreasing the active area. In more detail, the transition metal is a metal of various weights corresponding to about 1/5 times or more, more preferably 1/4 to 4 times the weight of the spherical carbon capsule structure of the hollow core structure of the present invention. Can carry.

Since the spherical carbon capsule structure of the hollow core structure used in the present invention has a surface area of about 4 to 10 times per unit mass as compared to the conventional carbon black carrier, the surface area on which the metal catalyst particles can be loaded is the same. In addition to supporting a larger amount of metal catalyst particles compared to carbon black by weight, it is possible to prepare a catalyst with a metal having a much smaller particle size (2 to 3 nm), thereby efficiently storing expensive precious metals. It is also economically advantageous as it becomes available. As a result, the relative weight of the metal can be widely chosen depending on the intended use. Furthermore, the spherical carbon capsule structure of the hollow core structure used in the supported catalyst synthesis of the present invention has a macropore having a constant diameter of 30 nm or more, preferably 30 nm to 1000 nm, and a diameter of 2 for the outer shell. The uniformly sized mesopores in the range of nm to 20 nm are well developed in three dimensions and are interconnected to free the movement and diffusion of the fuel, allowing the fuel to easily reach the surface of the catalyst so that the reaction can proceed quickly. Reaction products also have the advantage of being easily discharged.

The polyalkylene oxide copolymer may be used in an amount of 0.01 to 5 wt% based on the total weight of the HCMS carbon supported catalyst for fuel cell electrodes. In this case, when the polyalkylene oxide copolymer is less than 0.01 wt%, the effect of dispersing metal particles may be increased. Problems that may be difficult to see may occur, and excessively more than 5% by weight of micelles may cause a problem that the metal catalyst may be eluted with the copolymer to wash less of the metal catalyst. It is preferable.

The above-described HCMS carbon supported catalyst for fuel cell electrode of the present invention can be used for an anode or a cathode of a fuel cell, and a general fuel electrode can be used, and is not particularly limited, but particularly includes a hydrogen fuel proton exchange membrane. It is good to use for the anode or the cathode of the polymer electrolyte membrane fuel cell.

Hereinafter, a method of preparing the HCMS carbon supported catalyst for fuel cell electrode according to the present invention will be described.

The production method of the HCMS carbon supported catalyst for fuel cell electrode of the present invention

(A) a slurry in water of a spherical carbon capsule structure (HCMS carbon capsule structure) of a hollow core structure; (B) an aqueous solution in which a water-soluble metal salt having a catalytic activity is dissolved; And (c) a single type or two types of copolymers selected from a polyalkylene oxide copolymer and an alkyl polyethylene oxide copolymer; a first step of preparing a mixed solution by mixing;

A second step of diluting and stirring distilled water into the mixed solution such that the concentration of the water-soluble metal salt is 1 mM to 5 mM;

A third step of preparing a reaction solution by adjusting the pH of the diluted mixed solution to 8-9;

A fourth step of preparing a catalyst by adding a reducing agent to the reaction solution to reduce the water-soluble metal salt to form metal particles, and then supporting the formed metal particles on the carbon capsule structure; And

And a fifth step of separating the catalyst from the reaction solution.

In addition, the present invention

And a sixth step of washing and drying the catalyst separated from the reaction solution in the fifth step.

When explaining the steps of the manufacturing method in detail,

The electrode catalyst manufacturing method of the fuel cell according to the present invention has a large surface area and fine pores of metal catalyst particles which are reduced by slowly adding a carbon dispersion solution and a reducing agent to a solution of a metal salt under stirring at a relatively simple method without a complicated process. Not only uniformly dispersed on the porous spherical carbon capsule carrier having a volume, it is possible to produce metal catalyst particles of extremely fine size (2 ~ 3nm). In addition, the use of single or two types of copolymers selected from polyalkylene oxide copolymers and alkyl polyethylene oxide copolymers together helped to control the dispersion of catalyst particles and to control the size.

In the first step, the HCMS carbon capsule structure is the same as described above, wherein the water-soluble metal salt represents a salt form of the transition metal, the water-soluble salt of the metal to be catalyzed may be an acid salt or a basic salt. Examples of the water-soluble metal salt include H ₂ PtCl ₆ in the case of platinum, and RuCl ₃ in the case of ruthenium. The amount of these metal salts to be used may be determined stoichiometrically depending on the amount of metal to be supported on the catalyst support. For example, when using a Pt-Ru alloy, its use ratio may also be determined by stoichiometric calculation. The concentration of dissolving the water-soluble metal salt in water may also be determined according to the solubility in water according to the kind of the salt. The step of preparing the aqueous solution may vary depending on the solubility and concentration of each metal salt, the dissolution temperature, etc., but it is usually sufficient to stir for about 20 minutes to 1 hour. In addition, since the polyalkylene oxide copolymer or alkyl polyethylene oxide copolymer is also well dispersed in water, it may be sufficiently mixed with a stirring time of about 1 hour. And the polyalkylene oxide copolymer and alkyl polyethylene oxide copolymer is used the same as described above.

In the first step, the copolymer may be used 50 to 70 times the total weight of the metal catalyst used in the production of the water-soluble metal salt, when the copolymer is less than 50 times the micelle (micelle) of the copolymer It may not be able to accommodate all of the metal particles may cause a problem of agglomeration between the metal particles, when the excess of 70 times the micelle is excessively generated in the copolymer, when washing, the metal catalyst elutes with the polyalkylene oxide copolymer, so that less metal catalyst It is preferable to use within the above ranges as a problem may arise.

The HCMS carbon capsule structure is used in the form of a slurry in water as a carrier. For example, a carrier is added to water at an appropriate amount of carbon carrier relative to 100 ml of water, and prepared by stirring. At this time, the carrier aggregate may be separated into individual particles, and sonication may be performed in the middle of stirring to degas the air in the pores of the carrier. The slurry in water is prepared in a separate vessel and mixed with the water soluble metal salt in a reaction vessel.

In the second step, the molar concentration of the water-soluble metal salt is preferably 1 mM to 5 mM, preferably 1 mM to 3 mM, more preferably 1.5 mM to 2 mM, the water contained in the water-soluble metal salt solution It is calculated as the concentration of water-soluble metal salts relative to the total amount of water introduced by the water and other sources contained in the slurry in water and in water. The dilution of the concentration of the water-soluble metal salt is to prevent the metal particles from growing by aggregating and agglomerating the metal particles with each other when the metal particles are precipitated through a reduction reaction in the following step. That is, a problem occurs that the molar concentration of the water-soluble metal salt 5 m M, and in excess may cause problems due to agglomeration larger the metal particles of the metal particles, is so low that the concentration of the water-soluble metal salt during less than 1mM difficult precipitation of sufficient metal particles Can be. In addition, the growth of the particles is controlled by the above-mentioned polyalkylene oxide copolymer, metal particles are formed to a certain size, and are evenly dispersed. At this time, the stirring time is suitable about 1 to 2 hours.

In the third step, the reason for adjusting the pH to 8 to 9 is to adjust the appropriate pH range in advance so that the smooth reduction reaction can proceed in the reduction reaction of the fourth step. At this time, the pH control may be used an acid or a basic aqueous solution such as NaOH, such as HCl or HNO ₃ commonly used, the present invention is not particularly limited thereto.

The fourth step is a step of reducing the transition metal in the water-soluble metal salt state in the form of metal particles and supported on the carrier, the reducing agent is NaBH ₄ , LiBH ₄ , HCHO, HCOOH, CH ₃ OH, CH ₃ CH ₂ OH, One or two or more reducing agents selected from HCOONa, N ₂ H ₄ and AlBH ₄ may be used, and an excess is used relative to the number of moles of the water-soluble metal salt to be reduced. For example, an excess amount of NaBH ₄ aqueous solution is used to produce hydrogen (H) that is equivalent to 8 to 12 times, more preferably about 10 times, the number of moles of the water-soluble metal salt. And the metal particles have a size of 1 ~ 4 nm, more preferably 2 ~ 3 nm.

The fifth step is to precipitate the HCMS carbon supported catalyst prepared in the fourth step by allowing the reaction solution to stand still, and then separating the HCMS carbon supported catalyst from the reaction solution.

In the sixth step, the washing is a step of exfoliating the polyalkylene oxide copolymer used on the surface of the metal catalyst to expose the catalyst metal for use in the reaction. The washing is repeated with water and dried. The washing process is a process for removing impurities such as chlorine contained in the water-soluble metal salt.

The above steps are carried out under an air atmosphere at room temperature and atmospheric pressure, unless otherwise specified, and the water used is preferably distilled water or deionized water.

The above-described HCMS carbon supported catalyst for fuel cell electrodes of the present invention and a catalyst prepared by the method for preparing the same may be used in a fuel cell, and may also be used in an anode or a cathode of a fuel cell. The HCMS carbon supported catalyst of the present invention is preferably used for another type of polymer electrolyte membrane fuel cell including a hydrogen fuel proton exchange membrane fuel cell.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited thereto.

Production Example

Preparation of HCMS Carbon Capsule Structure (Spherical Carbon Capsule Structure with Hollow Core Structure)

Similar to the method described in Korean Patent Registration No. 10-0500975, a hollow core carbon capsule structure having a mesoporous outer shell was prepared as follows.

After synthesis of spherical silica particles having a diameter of about 350 nm, a solid core with mesoporous is added to the mesoporous silica shell by forming an outer shell using a TEOS / C ₁₈ -TMS mixture on the surface and heat-treating it. shell) silica template particles were synthesized. Thereafter, phenol and formaldehyde carbon precursor were injected into the mesoporous outer shell of the mesoporous shell and polymerized by heating to obtain a polymer-silica template composite. In addition, the mesophase pitch was heated to a softening point or more using a mesophase pitch, injected into the SCMS silica mold, and polymerized to obtain a polymer-silica mold composite.

The polymer-silica composite was carbonized under 900 ° C to 1000 ° C and inert gas such as nitrogen, argon, and helium to obtain a carbon-silica composite, followed by melting the silica template with hydrofluoric acid (HF) solution. A spherical HCMS carbon capsule structure was prepared in which the pores of a certain size were formed in a portion where silica was dissolved, that is, the center had a macro pores of a constant size and the outer shell was mesoporous.

SEM and TEM images of the HCMS carbon capsule structure prepared above are shown in FIGS. 1 and 2, respectively. In addition, the surface area was measured by the BET method, and it was confirmed that the surface area was about 2000 m ² / g.

According to the same procedure as described above, the SCMS silica template having a hollow inner diameter of about 150 nm was synthesized, and the surface shape was roughly or smoothly adjusted by adjusting the proportion of the carbon precursor and changing the type of the carbon precursor. To FIG. 6. These HCMS carbon encapsulated structures showed similar mesopore distribution and surface properties of the SCMS silica mold shells, depending on the distribution and surface characteristics of the uniform size of mesopores formed on the shell of the SCMS silica mold. Pore distribution is shown in FIG. 7.

Preparation of HCMS Carbon Supported Catalyst for Fuel Cell Electrode

Example 1

The aqueous solution of the metal was prepared in a 250 ml beaker with 0.0865 g H ₂ PtCl ₆ (Aldrich's reagent grade, 38.08 wt.% Pt) and RuCl ₃ (Aldrich's reagent grade, 40.0 wt. ) 0.0427 g was added to 80 ml of distilled water, and stirred for 30 minutes to prepare a solution. The H ₂ PtCl ₆ and While RuCl ₃ was dissolved, 6 ml of Pluronic L64 [(EO) ₁₃ (PO) ₃₀ (EO) ₁₃ ], a polyalkylene oxide copolymer, was added thereto and stirred to mix well. After stirring, a mixed solution of a water-soluble metal salt and a polyalkylene oxide copolymer was transferred to a 3 L beaker. 0.20 g of the HCMS carbon capsule structure prepared in Preparation Example was mixed with 150 ml of distilled water in a separate 250 ml beaker, followed by stirring for 30 minutes to prepare a slurry, and then into the 3 L Erlenmeyer flask containing an aqueous solution of a metal salt solution. The mixture was slowly added with stirring, followed by dilution with distilled water so that the total concentration of the water-soluble metal salt was about 2 mM, followed by stirring for 1 hour. Thereafter, the pH was adjusted to about 8.5 using a 20 wt% NaOH solution, and 40 ml of an aqueous solution in which 1.6 g of NaBH _{4 as a} reducing agent was dissolved was mixed with the HCMS carbon capsule structure, the water-soluble metal salt, and the polyalkylene oxide copolymer. The solution was added slowly and stirred for about 2 hours to allow metal particles to be supported on the HCMS carbon capsule structure. After stopping the stirring and leaving the solution clear, the filter was filtered using 0.2 ㎛ nylon filter paper, washed several times with distilled water and dried at 80 ℃ to prepare a Pt-Ru alloy catalyst, HCMS carbon supported catalyst for fuel cell electrodes It was. The TEM photograph of the prepared Pt-Ru alloy catalyst is shown in FIG. 8, and as can be seen from FIG. 8, Pt-Ru metal particles having a size of about 2 to 3 nm are uniformly synthesized and uniformly dispersed. have.

Example 2-Example 4

Example 2 to Example 4 were carried out in the same manner as in Example 1, except that Example 2 was water-soluble using 0.1313 g of H ₂ PtCl ₆ (Aldrich's reagent grade, 38.08 wt% Pt) instead of the aqueous Pt and Ru mixed solution. Pt solution was used, and Example 3 and Example 4 were carried out in the same manner as in Example 1, but was carried out to have a composition ratio as shown in Table 1 below.

Composition ratios of the HCMS carbon supported catalyst for fuel cell electrodes prepared in Examples 1 to 4 are shown in Table 1 below.

Classification (% by weight) Example 1 (Pt-Ru Alloy Catalyst) Example 2 (Pt Catalyst) Example 3 (Pt-Ru Alloy Catalyst) Example 4 (Pt-Ru Alloy Catalyst) HCMS Carbon Capsule Structure 80 80 39.9 19.8 Transition metal 19.8 19.8 59.9 80 Polyalkylene oxide copolymer 0.2 0.2 0.2 0.2 Total weight 100 wt%

Comparative Example 1 to Comparative Example 2

Comparative Example 1 was carried out in the same manner as in Example 1, but prepared a Pt-Ru alloy catalyst using Vulcan XC-72 (Cabot) as a carrier instead of the HCMS carbon capsule structure prepared in Preparation Example as a carrier, Example 2 was compared to the present invention using a commercial Pt-Ru alloy catalyst (molar ratio 1: 1, E-TEK, USA) loaded with a total of 20% by weight metal.

Comparative Example 3 to Comparative Example 4

Comparative Example 3 was carried out in the same manner as in Example 2, Pt catalyst was prepared using Vulcan XC-72 (Cabot) as a carrier instead of the HCMS carbon capsule structure prepared in Preparation Example as a carrier, Comparative Example 4 A total of 20 weight percent metal loaded commercial Pt catalyst (E-TEK, USA) was compared with the present invention.

Comparative Example 5

A Pt-Ru alloy catalyst, which is a HCMS carbon supported catalyst for fuel cell electrodes, was prepared in the same manner as in Example 1, without adding a triblock copolymer L64, which is a polyalkylene oxide copolymer.

Experimental Example 1

X-ray Diffraction Analysis Pattern Experiment

The X-ray diffraction analysis pattern of the HCMS carbon supported catalyst (Pt-Ru / HCMSC) for the fuel cell electrode prepared in Example 1 was compared with the catalyst (Pt-Ru / VC) of Comparative Example 1 and E-TEK, Inc. of the United States. It was compared with the commercial Pt-Ru alloy catalyst (Pt-Ru / VC-ETek) of Comparative Example 2 commercially purchased from the XRD pattern, the results are shown in FIG. Referring to FIG. 10, the 2θ value of about 68 ° corresponds to the (220) plane of the Pt metal crystal, which is a Pt-Ru catalyst prepared according to Example 1, similar to a commercially available Pt-Ru catalyst of E-TEK. In addition, it can be inferred that the alloy (alloy), and also, the peak of the catalyst according to Example 1 is broader than the peaks of Comparative Example 1 and Comparative Example 2 (broad), Comparative Example 1 and Comparative Example 2 It can be seen that the size of the metal particles is smaller than that of the catalyst, and the metal particles are more uniformly dispersed. 11 is an X-ray diffraction analysis pattern of the HCMS carbon supported catalyst (Pt / HCMSC) for fuel cell electrode prepared in Example 2 catalyst (Pt / VC) of Comparative Example 3 and E-TEK, Inc. of the United States. It was compared with the commercial Pt catalyst (Pt / VC-ETek) and XRD pattern of Comparative Example 4 commercially obtained from, the size of the transition metal particles are obtained by 2 ~ 3 nm by the actual TEM photograph and calculation.

Experimental Example 2

Hydrogen Oxidation Performance Test of Catalyst

Hydrogen oxidation performance of the Pt-Ru alloy catalyst obtained according to the method of Example 1 was also confirmed through the unit cell performance test, respectively, the oxygen reduction reaction performance of the Pt catalyst of Example 2, Comparative Examples 1, 2 and comparison The results are shown in FIGS. 12 and 13 as compared with the catalysts of Examples 3 and 4.

12 is a result of confirming the hydrogen oxidation reaction performance through a unit cell performance test comparing the Pt-Ru / HCMSC anode catalyst obtained according to the method of Example 1 with the Comparative Examples 1 and 2 catalyst, Figure 13 is Example 2 Pt / HCMSC cathode catalyst obtained according to the method is compared with the comparative examples 3 and 4 catalyst shows the results of oxygen reduction performance. At this time, the performance test was carried out under the conditions of electrode cross-sectional area of 6.25 cm ² , 200 sccm H ₂ , and 1000 sccm O ₂ .

12, it can be seen that compared with the catalysts of Comparative Example 1 and Comparative Example 2, the catalyst of Example 1 has a much higher battery voltage for the hydrogen oxidation reaction. In addition, it can be seen that the change in power density according to the change of current density in the unit performance test result is also superior to that of the E-TEK catalyst of Comparative Example 2. In FIG. 13, the catalyst of Example 2 was much more oxygen-reduced voltage density and power density than the catalysts of Comparative Example 3 and Comparative Example 4.

Referring to FIG. 14, the HCMS carbon supported catalyst (Pt-Ru / HCMSC) for the fuel cell electrode prepared in Example 1 was not added with Pluronic L64, which serves to uniformly disperse the metal particles in the carrier. It can be seen that the oxygen reduction performance is superior to that of the catalyst of Comparative Example 5 and Pt-Ru alloy catalyst using Vulcan XC-7 of Comparative Example 1 as a carrier.

From the above results, the Pt-Ru alloy catalyst (Example 1) prepared by using the carbon capsule structure of the hollow core with mesoporous shell (HCMS) structure as a carrier (Example 1) was Vulcan XC-72 of Comparative Example 1. Pt-Ru alloy catalyst ((Pt-Ru / VC) prepared by using as a carrier and commercial Pt-Ru alloy catalyst (Pt-Ru / VC-ETek commercially purchased from E-TEK Inc. of Comparative Example 2) Pt catalyst ((Pt / VC) and U.S. E- of Comparative Example 4) prepared for hydrogen oxidation and Pt / HCMSC catalyst (Example 2) were also prepared using Vulcan XC-72 of Comparative Example 3 as a carrier. It can be seen that TEK's commercially available Pt catalyst (Pt / VC-ETek) shows superior activity for oxygen reduction reaction.

FIG. 1 is a scanning electron microscope (SEM) photograph of a hollow core with mesoporous shell (HCMS) carbon capsule structure prepared in a preparation example.

FIG. 2 is a transmission electron microscope (TEM) photograph of HCMS carbon capsule structures of uniform size with irregular mesoporous distribution prepared in Preparation.

3 is a BET (Brunauer-Emmett-Teller) adsorption-desorption isotherm of the hollow carbon capsule structure prepared in Preparation Example.

4 to 6 is a hollow carbon capsule structure synthesized by adjusting the surface roughness by varying the type and ratio of the carbon precursor, Figure 4 is a hollow carbon capsule structure of a smooth surface, Figure 5 is an intermediate surface roughness It is a hollow carbon capsule structure having a, Figure 6 is a hollow carbon capsule structure of the rough surface.

7 is a TEM image of a solid core with mesoporous shell (SCMS) silica template prepared in Preparation Example.

8 is a HCMS carbon supported Pt-Ru for a fuel cell electrode prepared in Example 1; Alloy catalyst.

9 is a HCMS carbon-supported Pt catalyst for a fuel cell electrode prepared in Example 2. FIG.

10 is a HCMS carbon supported Pt-Ru for a fuel cell electrode according to Example 1 of the present invention. Alloy catalyst and Pt-Ru supporting vulcan carbon of Comparative Example 1 Alloy Catalysts and Commercial Pt-Ru of Comparative Example 2 This graph shows the X-ray diffraction pattern of alloy catalyst.

11 is a HCMS carbon supported Pt catalyst for a fuel cell electrode of Example 2 of the present invention and a vulcan carbon supported Pt of Comparative Example 1 Catalyst and Comparative Example 2 A graph showing an X-ray diffraction analysis pattern of a commercial Pt catalyst.

12 is a HCMS carbon supported Pt-Ru for a fuel cell electrode of Example 1 Alloy catalyst and Pt-Ru supporting vulcan carbon of Comparative Example 1 Alloy Catalysts and Commercial Pt-Ru of Comparative Example 2 This is a graph showing the unit cell performance curves tested at 60 ^° C oxygen conditions with an alloy catalyst as an anode.

FIG. 13 is a 20 wt% Pt catalyst supported on the HCMS carbon capsule structure synthesized in Example 2 of the present invention, a commercial E-TEK Pt catalyst, and a Pt catalyst supported on Vulcan carbon under a 60 ^° C oxygen test using a reducing electrode. One unit cell performance curve.

14 is a HCMS carbon-supported Pt-Ru for fuel cell electrode synthesized in Example 1 of the present invention. It is a graph showing the unit cell performance curve of the alloy catalyst and the catalysts prepared in Comparative Examples 1 and 5 were tested under an oxygen condition of 60 ^° C as an anode.

Claims (13)

A spherical carbon capsule structure having a hollow core with mesoporous shell structure having an inner shell having a macro hollow and an outer shell having mesopores; Transition metals; And HCMS carbon-carrying catalyst for a fuel cell electrode, characterized in that it comprises a; polyalkylene oxide copolymers and alkyl polyethylene oxide copolymers of one or two selected. The method according to claim 1, 15 to 84% by weight of the spherical carbon capsule structure; 15 to 80% by weight of the transition metal; And 0.01 to 5% by weight of the copolymer; HCMS carbon supported catalyst for a fuel cell electrode comprising a. The HCMS carbon supported catalyst for fuel cell electrode according to claim 1, wherein the macro hollow has a diameter of 30 nm to 1000 nm and the mesopores have a diameter of 2 nm to 20 nm. The method of claim 1, wherein the transition metal is platinum (Pt), ruthenium (Ru), rhodium (Rh), molybdenum (Mo), osmium (Os), iridium (Ir), rhenium (Re), palladium (Pd), vanadium (V), tungsten (W), cobalt (Co), iron (Fe), selenium (Se), nickel (Ni), bismuth (Bi), tin (Sn), chromium (Cr) and copper (Cu) HCMS carbon supported catalyst for fuel cell electrodes, characterized in that selected single or two or more. The method of claim 1, wherein the polyalkylene oxide copolymer is poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) triple block copolymer [poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) triblock copolymer] The triple block copolymer is one or more selected from Pluronic L31, Pluronic L35, Pluronic L42, Pluronic L61, Pluronic L62, Pluronic 62D, Pluronic L62LF, Pluronic L63, Pluronic L64, Pluronic L65, Pluronic L72 and Pluronic L92 HCMS carbon supported catalyst for fuel cell electrodes. The HCMS carbon supported catalyst for fuel cell electrode according to any one of claims 1 to 5, wherein the fuel cell electrode is an anode or a cathode. A fuel cell comprising the catalyst of any one of claims 1 to 5. The fuel cell of claim 7, wherein the fuel cell is a polymer electrolyte membrane fuel cell including a hydrogen fuel proton exchange membrane. (A) an underwater slurry of a spherical carbon capsule structure having a hollow core structure; (B) an aqueous solution in which a water-soluble metal salt having a catalytic activity is dissolved; And (C) a single or two types of copolymers selected from polyalkylene oxide copolymers and alkylpolyethylene oxide copolymers; A first step of preparing a mixed solution by mixing; A second step of diluting and stirring distilled water into the mixed solution such that the concentration of the water-soluble metal salt is 1 mM to 5 mM; A third step of preparing a reaction solution by adjusting the pH of the diluted mixed solution to 8-9; A fourth step of preparing a catalyst by adding a reducing agent to the reaction solution to reduce the water-soluble metal salt to form metal particles, and then supporting the formed metal particles on the carbon capsule structure; And And a fifth step of separating the catalyst from the reaction solution. The fuel cell according to claim 9, wherein the reducing agent is one or more selected from NaBH ₄ , LiBH ₄ , HCHO, HCOOH, CH ₃ OH, CH ₃ CH ₂ OH, HCOONa, N ₂ H ₄ and AlBH ₄ . Method for producing HCMS carbon supported catalyst for electrodes. The method of claim 9, wherein the water-soluble metal salt is platinum (Pt), ruthenium (Ru), rhodium (Rh), molybdenum (Mo), osmium (Os), iridium (Ir), rhenium (Re), palladium (Pd), vanadium (V), tungsten (W), cobalt (Co), iron (Fe), selenium (Se), nickel (Ni), bismuth (Bi), tin (Sn), chromium (Cr) and copper (Cu) A method for producing a HCMS carbon supported catalyst for fuel cell electrodes, characterized in that selected single or two or more metal salts. 10. The method of claim 9, wherein the metal particles have a size of 1 to 4 nm. The method according to claim 9, wherein the copolymer is used for producing a HCMS carbon supported catalyst for a fuel cell electrode, characterized in that 50 to 70 times the total weight of the metal catalyst used in the production of the water-soluble metal salt.

Images