KR20100063481A - Method for preparing supported catalysy for fuel cell - Google Patents

Abstract

PURPOSE: A manufacturing method of a supported catalyst for a fuel cell is provided to mass-produce the supported catalyst for the fuel cell including the excellent electro-activity with a simple process. CONSTITUTION: A manufacturing method of a supported catalyst for a fuel cell comprises the following steps: forming a metal precursor mixture solution including a base catalyst metal precursor, and ionic liquid; forming a reduced resultant by reducing the metal precursor mixture solution; purifying the reduced resultant and collecting the ionic liquid; and drying the purified product. The base catalyst metal precursor is chloride of platinum, a nitride, an oxide, or a halogenide.

Description

Method for preparing supported catalyst for fuel cell {Method for preparing supported catalysy for fuel cell}

A method for producing a catalyst for a fuel cell, a fuel cell electrode including a catalyst prepared according to the production method, a membrane electrode assembly including the electrode, and a fuel cell including the membrane electrode assembly are disclosed. More specifically, A method for producing a catalyst for a fuel cell, which has a small size and shows excellent activity even in high tack, a fuel cell electrode including the catalyst prepared according to the manufacturing method, a membrane electrode assembly including the electrode, and the membrane electrode assembly A fuel cell is disclosed.

With the development of science and technology, the need for a high-capacity power source is increasing. However, the conventional lithium secondary battery does not meet this need, and has a disadvantage in that it has a short time and a long life of recharging after a short time of use. As a solution to this, environmentally friendly, high energy density and long life fuel cells have attracted attention as next generation power sources.

Such fuel cells are polymer electrolyte membrane fuel cells (PEMFC), phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC) depending on the type of electrolyte used. cell), solid oxide fuel cell (SOFC), etc., depending on the electrolyte used, the operating temperature of the fuel cell and the material of the components are different. In addition, according to the fuel supply method to the anode, the external reforming type for converting the fuel to hydrogen-enriched gas through the fuel reformer and supplying to the anode, and the fuel direct supply type for supplying gas or liquid fuel directly to the anode or It can be divided into internal reforming type. A representative example of the direct fuel supply type is a direct methanol fuel cell (DMFC), and a direct methanol fuel cell generally uses an aqueous methanol solution as a fuel and a hydrogen ion conductive polymer electrolyte membrane as an electrolyte. Therefore, DMFC also belongs to PEMFC. PEMFCs can achieve high power density, even at small and light weights. Moreover, the use of PEMFCs simplifies the construction of power generation systems.

The basic structure of a fuel cell typically includes an anode (fuel electrode), a cathode (oxidant electrode), and a polymer electrolyte membrane disposed between the anode and the cathode. The anode is provided with a catalyst layer for promoting the oxidation of the fuel, and the cathode is provided with a catalyst layer for promoting the reduction of the oxidant. In the anode, the fuel is oxidized to produce hydrogen ions and electrons, the hydrogen ions are transferred to the cathode through the electrolyte membrane, and the electrons are transferred to the external circuit (load) through the conductor (or current collector). In the cathode, water is generated by combining hydrogen ions transferred through the electrolyte membrane, electrons transferred from an external circuit through a conductor (or current collector), and oxygen. At this time, the movement of electrons via the anode, the external circuit and the cathode is power. As such, the cathode and / or anode of the fuel cell contains a catalyst that promotes electrochemical oxidation of the fuel and / or electrochemical reduction of oxygen.

Fuel cell catalysts are generally prepared in the liquid phase. In this case, mass production is easy because the process variables are not large and the manufacturing process is simple. As a method for preparing a fuel cell catalyst, for example, a colloidal method for preparing an electrode catalyst for methanol fuel cell directly in an aqueous solution has been studied by Watanabe et al. (Journal of Electroanl. Chem., 229). , 395 (1987). This process involves the multi-step process of adding a reducing agent (eg, Na ₂ CO ₃ or NaHSO ₄ ) to a hydrated platinum chloride (H ₂ PtCl ₆ .xH ₂ O) and an aqueous solution of a second metal chloride to produce and produce a metal complex intermediate. A method for producing nano-sized platinum alloy particles by hydrolysis of the intermediates to form metal oxides and heat treatment, according to the type of reducing agent added in each step and the pH (pH) accompanying between the processes The size of the platinum alloy changes sensitively and has the disadvantage of requiring heat treatment. As another example, a colloidal method for preparing an electrocatalyst for a methanol fuel cell directly on a non-aqueous solution has been studied by Bonnemann et al. (Angew. Chem. Int. Ed. Engl., 30 (10)). , 1312 (1991). This method is to prepare a surfactant-stabilized catalyst by using a synthesized tetrabutylammonium-based reducing agent and to remove the surface active agent surrounding the catalyst by heat treatment. It has the advantage of being uniform around 2nm and easy to disperse in carbon, but has the disadvantage that the size of the particle is slightly increased due to the complicated and essential heat treatment.

In order to increase the activity of the fuel cell, it is preferable that such a catalyst is supported in an alloy form. However, in the prior art including a high temperature heat treatment process, an increase in catalyst particle size is inevitable, thereby decreasing activity.

One aspect of the present invention is to provide a method for producing a catalyst for a fuel cell, the particle size of which shows excellent activity even in the case of high support.

Another aspect of the present invention is to provide an electrode for a fuel cell comprising a catalyst prepared according to the above production method.

Another aspect of the invention to provide a membrane electrode assembly comprising the electrode.

Another aspect of the present invention is to provide a fuel cell including the membrane electrode assembly.

According to one aspect of the invention,

Preparing a metal precursor mixed solution comprising a main catalyst metal precursor and an ionic liquid;

Reducing the metal precursor mixed solution with a reducing agent to prepare a reduction product;

Purifying the reduction product and recovering the ionic liquid; And

Provided is a method for preparing a catalyst for a fuel cell comprising the step of drying the purified product.

According to another aspect of the invention there is provided an electrode for a fuel cell comprising a catalyst prepared according to the above production method.

According to another aspect of the invention there is provided a membrane electrode assembly comprising the electrode.

According to another aspect of the invention there is provided a fuel cell comprising the membrane electrode assembly.

According to one aspect of the present invention, it is possible to provide a supported catalyst for a fuel cell having excellent electrical activity in a simple process and in large quantities, and to provide a high performance membrane electrode assembly and a fuel cell having excellent power density.

Hereinafter, a method for manufacturing a catalyst for a fuel cell according to an embodiment of the present invention, a fuel cell electrode including a catalyst prepared according to the production method, a membrane electrode assembly including the electrode and a fuel cell including the membrane electrode assembly This will be described in more detail.

According to one embodiment of the present invention, it is possible to provide a method for producing a catalyst for a fuel cell, which exhibits excellent activity even in the case of high support because of the small particle size.

A method of preparing a catalyst for a fuel cell according to an embodiment of the present invention includes the steps of preparing a mixed metal precursor solution by mixing the main catalyst metal precursor and the ionic liquid; Reducing the metal precursor mixed solution with a reducing agent to prepare a reduction product; Purifying the reduction product and recovering the ionic liquid; And it includes a method for producing a catalyst for a fuel cell comprising the step of drying the purified result.

That is, the method for producing a catalyst for a fuel cell, by mixing the main catalyst metal precursor and the ionic liquid to prepare a metal precursor mixed solution, and reducing it with a reducing agent provides a high catalyst alloy catalyst for the small particle size. It is possible to control the particle size of the active metal by using the fuel cell catalyst production method according to an embodiment of the present invention, to have a high yield manufacturing process by using an ionic liquid, and to recover the ionic liquid Reuse may facilitate the purification process.

According to one embodiment of the invention, the main catalyst metal precursor may be a chloride, nitride, oxide or halide of platinum, specifically tetrachloroplatinic acid (H ₂ PtCl ₄ ), hexachloroplatinic acid (H ₂ PtCl ₆ ), Potassium tetrachloroplatinate (K ₂ PtCl ₄ ), hexachloroplatinate (K ₂ PtCl ₆ ), Pt (NH ₃ ) ₂ (NO ₂ ) ₂ , and Pt (NH ₃ ) ₄ Cl ₂ It may be one or more, but is not limited thereto.

The ionic liquid refers to a salt that is water-soluble or fat-soluble and consists of a cation and an anion. The ionic liquid has almost no vapor pressure in the chemical process, and has a very polar property compared to the conventional organic solvent, but has a very low coordination power, and has the characteristics of bringing raw materials of different properties into the same phase.

As the cation of the ionic liquid may be selected from the formula of Table 1.

TABLE 1

, 시아노기 등으로 치환될 수 있다In Table 1, R, R 'and R "are independently a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, wherein the alkyl group is a straight or branched alkyl group having 1 to 12 carbon atoms, or 1 to 6 carbon atoms. Linear or branched alkyl groups, and examples of such unsubstituted alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, isoamyl, Hexyl, etc. One or more hydrogen atoms contained in the alkyl group include a halogen atom, a hydroxy group, -SH, a nitro group,

, Cyano group and the like can be substituted

As the anion, halides, alkylsulfonyls, haloalkylsulfonyls, phosphoryls, imides, nitrates or carbonyl groups of elements of group VIII, IB, 2B, IIIA, and VA on the periodic table (CAS version) may be selected. .

Specific examples of the ionic liquids include 1-ethyl-3-methyl-imidazolium (EMIM) and 1-methyl-3-propyl-imidazoli 윰 (1-methyl -3-propyl-imidazolium (PMIM), 1-butyl-3-methyl-imidazolium (BMIM), 1-methyl-3-pentyl-imidazoli 윰 (1 -methyl-3-pentyl-imidazolium (PnMIM), 1-hexyl-3-methyl-imidazolium (HMI), 1- and heptyl-3-methyl-imidazoli 양이온 (1-heptyl-3-methyl-imidazolium (HpMIM)) selected from the group consisting of hexafluoroantimonate (SbF ₆ ), hexafluorophosphate (PF ₆ ), tetrafluoroborate (BF ₄ ) , An imide containing an anion selected from the group consisting of bis (trifluorosulfonyl) imide (NTf ₂ ), trifluoromethanesulfonate (OTf), acetate (OAc), and nitrate (NO ₃ ) Jolyzek salts, but is not limited thereto.

The content of the ionic liquid may be, for example, 10 to 200 parts by weight, 25 to 100 parts by weight, and 30 to 80 parts by weight based on 100 parts by weight of the main catalyst metal precursor. At this time, if the content of the ionic liquid is less than 10 parts by weight of the particle stability effect of the active metal particles is insufficient to increase the size of the active particles, if more than 200 parts by weight may be effective in controlling the size of the active particles, but the purification process is long Economics can fall.

According to an embodiment of the present invention, the metal precursor mixed solution may further include a cocatalyst metal precursor. When the cocatalyst metal precursor is further included, it is possible to control the increase in the particle size of the active metal due to alloy formation as compared with the case of using the main catalyst metal precursor alone. There may be.

The cocatalyst metal precursor is a chloride, nitride, oxide or at least one metal selected from the group consisting of cerium, ruthenium, tin, tungsten, titanium, molybdenum, iron, vanadium, manganese, cobalt, chromium, nickel, palladium, rhodium and iridium Halide, more specifically (NH ₄ ) ₂ [RuCl ₆ ], (NH ₄ ) ₂ [RuCl ₅ H ₂ 0], RuCl ₃ · 3H ₂ O, (CH ₃ COO) ₂ Co.4H ₂ One or more selected from the group consisting of O, CoCl ₂ · 6H ₂ O, CoSO ₄ · 7H ₂ O, CoF ₂ and Co (NO ₃ ) ₂ · 6H ₂ O, but is not limited thereto.

The content of the cocatalyst metal precursor may be determined in consideration of the alloy ratio of the alloy catalyst to be prepared, and specifically 0.5 to 300 parts by weight, 10 to 150 parts by weight, 30 to 100 parts by weight based on 100 parts by weight of the main catalyst metal precursor. It may be part by weight. At this time, when the content of the cocatalyst metal precursor is less than 0.5 parts by weight, the effect of controlling the particle size and improving durability due to the alloying effect cannot be expected. If the content is greater than 300 parts by weight, the surface of the main catalyst metal is replaced with the cocatalyst metal. It can exhibit the effect of lowering the activity of the main catalyst metal.

Subsequently, a reduction step of the prepared metal precursor mixture solution is performed, wherein the reducing agent used in the reduction step includes alcohol, hydrazine, aldehyde, sodium borohydride, lithium borohydride, potassium borohydride, sodium thiosulfate, and the like. It may be one or more selected from the group. Examples of the alcohol include monoalcohols such as methanol and ethanol, ethylene glycol, propane-1,3-diol, 2-methylpropane-1,3-diol, hexane-1,6-diol or 1,10-decane. And dialcohols such as diols.

The content of the reducing agent may be determined in consideration of the alloy ratio of the alloy catalyst to be prepared. Specifically, in the case of a reduction method except an alcohol reduction method and a hydrogenation reduction method, the amount may be 0.8 to 5 equivalent parts, 1.0 to 4 equivalent parts, and 1.2 to 3 equivalent parts based on 1 molar equivalent of the anion salt of the metal precursor. In this case, when the content of the reducing agent is less than 0.8 equivalent parts, it may be difficult to make the alloy due to the insufficient reducing power, and when the content of the reducing agent is more than 5 equivalent parts, the size of the alloy particles and platinum particles due to excessive use of the reducing agent may increase.

Before preparing the reduction product by reducing the metal precursor mixed solution with a reducing agent, the method may further include adding and stirring a carbon support to the metal precursor mixture solution.

When the carbon support is further added to the metal precursor mixture solution, the carbon support itself may have an effect of controlling the size of the active metal particles by the absorption effect of the metal precursor.

The carbon support may be carbon black, ketjen black, acetylene black, activated carbon powder, carbon molecular sieve, carbon nanotubes, activated carbon having fine pores, mesoporous carbon, or a mixture thereof, but is not limited thereto. It is not.

The content of the carbon support may be 10 to 1,000 parts by weight, 25 to 500 parts by weight, and 50 to 300 parts by weight based on 100 parts by weight of the main catalyst metal precursor. In this case, when the content of the carbon support is less than 10 parts by weight, the amount of carbon support is insufficient, so that the effect of the carbon support becomes ineffective. If the content is more than 1,000 parts by weight, the density of the active catalyst decreases, thereby directly using a high content catalyst. It may be inappropriate for methanol fuel cells.

In addition, according to an embodiment of the present invention, there is provided a fuel cell electrode including a catalyst prepared by the manufacturing method, a membrane electrode assembly including the electrode, and a fuel cell including the membrane electrode assembly.

An electrode for a fuel cell according to an embodiment of the present invention may include an electrode substrate, a supported catalyst according to the manufacturing method of an embodiment of the present invention as described above, an electrode diffusion layer and a microporous layer, and the like, such as carbon paper. Carbon powders such as carbon black, acetylene black, carbon nanotubes, carbon nanowires, carbon nanohorns and carbon nanofibers on the electrode substrate; Binders such as polytetrafluoroethylene (PTFE: polytetrafluoroethylene), polyvinylidene fluoride (PVdF: polyvinylidenefluoride), and fluorinated ethylene propylene (FEP); And a dispersion medium such as water, ethanol, methanol, isopropyl alcohol, n-propyl alcohol, butyl alcohol, and the like, which are coated by a tape casting, spray, or screen printing method. Thereby forming a diffusion layer and a microporous layer with a uniform thickness, and then producing a slurry of a supported catalyst according to the production method of an embodiment of the present invention on the diffusion layer and the microporous layer by tape casting and spraying ( It may be prepared by coating by a method such as spray or screen printing.

The diffusion layer serves to make the reaction gas easily accessible to the catalyst layer, and also to prevent performance degradation due to water generated as a by-product when the battery is driven. On the other hand, the microporous layer serves to increase the performance of the diffusion layer.

Membrane Electrode Assembly (MEA) according to an embodiment of the present invention is an electrode including an anode and a cathode; And an electrolyte membrane disposed between the pair of electrodes.

The electrode is an electrode according to an embodiment of the present invention, and as the electrolyte membrane, a sulfonate high fluorinated polymer having a main chain generally composed of fluorinated alkylene and a side chain composed of fluorinated vinyl ether having a sulfonic acid group at its terminal (eg Polymer electrolytes such as Nafion (trademark of Dupont) may be used. Such a polymer electrolyte membrane exhibits excellent ion conductivity by impregnating an appropriate amount of water. Bonding of the electrode and the electrolyte membrane may be performed by a thermal press method or the like.

In addition, an embodiment of the present invention provides a fuel cell including the membrane electrode assembly, and the fuel cell includes at least one electricity generating unit, a fuel supply unit, and a gas supply unit. The electricity generating unit includes a positive electrode, a negative electrode, and a separator formed on both sides of the polymer electrolyte membrane, and the electrode and the separator may be integrally manufactured by using a metal mesh. The fuel supply unit serves to supply hydrogen or hydrogen-containing fuel, that is, alcohols such as methanol to the electricity generator, and the gas supply unit serves to supply oxygen or air including oxygen to the electricity generator.

Hereinafter, a direct methanol fuel cell of a fuel cell according to an embodiment of the present invention will be described with reference to FIG. 1.

As shown in FIG. 1, the DMFC includes an anode 20 to which fuel is supplied, a cathode 30 to which an oxidant is supplied, and an electrolyte membrane 40 positioned between the anode 20 and the cathode 30. . In general, the anode 20 consists of an anode diffusion layer 22 and an anode catalyst layer 21, and the cathode 30 consists of a cathode diffusion layer 32 and a cathode catalyst layer 31. The anode catalyst layer and the cathode catalyst layer is made of a supported catalyst prepared by the manufacturing method according to an embodiment of the present invention described above.

The anode separator 50 has a flow path for supplying fuel to the anode, and serves as an electron conductor for transferring electrons generated from the anode to an external circuit or an adjacent unit cell. The cathode separator 60 has a flow path for supplying an oxidant to the cathode, and serves as an electron conductor for transferring electrons supplied from an external circuit or an adjacent unit cell to the cathode. In DMFC, an aqueous methanol solution is mainly used as the fuel supplied to the anode, which is supplied from a fuel supply section, and air is mainly used as an oxidant supplied to the cathode, which is supplied from a gas supply section.

The aqueous methanol solution transferred to the anode catalyst layer 21 through the anode diffusion layer 22 is decomposed into electrons, hydrogen ions, carbon dioxide, and the like. Hydrogen ions are transferred to the cathode catalyst layer 31 through the electrolyte membrane 40, electrons are transferred to an external circuit, and carbon dioxide is discharged to the outside. In the cathode catalyst layer 31, hydrogen ions delivered through the electrolyte membrane 40, electrons supplied from an external circuit, and oxygen in the air delivered through the cathode diffusion layer 32 react to generate water.

In such a DMFC, the electrolyte membrane 40 serves as a hydrogen ion conductor, an electronic insulator, a separator, and the like. In this case, the role of the separator means that unreacted fuel is delivered to the cathode, or unreacted oxidant is prevented from being delivered to the anode.

Hereinafter, the present invention will be described in more detail with reference to the following examples. The following examples are only intended to help a clear understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Example

Synthesis Example 1 Ionic Liquid (3.1-Butyl-3-methylimidazolysone)

Synthesis of Bis (trifluorosulfonyl) imide)

54 g of 1-butyl-3-methylimidazoli oil chloride was added to 150 ml of acetone. 68 g (1.1 equiv) of lithium bis (trifluorosulfonyl) imide was added thereto and reacted for 24 hours, and then the reaction solution was filtered to remove salts. The filtrate was distilled off to remove acetone, to prepare 1-butyl-3-methylimidazolysin bis (trifluorosulfonyl) imide ionic liquid.

Example 1: Preparation of Pt black with Pt content of 100% by weight

10.0 g of chloroplatinic acid (H ₂ PtCl ₆ .6H ₂ O, 99%) and 4.0 g of the ionic liquid prepared in Synthesis Example 1 were added to 200 g of acetone and stirred at room temperature for 8 hours. Subsequently, a solution obtained by dissolving 6.3 g of sodium hydroxide and 4.9 g of sodium borohydride as a reducing agent in 20 g of demineralized water was added dropwise to the reaction vessel and reduced for 1 hour. Acetone is removed using reduced pressure, and excess methylene chloride is added to form a layer with the demineralized water layer. The demineralized water layer containing the reaction by-products is purified by layer separation, and demineralized water is added again to repeat the purification method by layer separation to complete the purification process. The methylene chloride layer is then purified with a filter to recover the ionic liquid to obtain a catalyst. Pt black having a Pt content of 100% by weight was prepared by drying at 80 ° C. for 12 hours. (99% yield)

The recovered ionic liquid is distilled under reduced pressure from methylene chloride to be obtained as an ionic liquid and methylene chloride, which can be reused.

Example 2: Preparation of Pt-Ru black with Pt-Ru content of 100% by weight

In the reaction vessel, 10.0 g of chloroplatinic acid (H ₂ PtCl ₆ 6H ₂ O, 99%), 4.94 g of ruthenium chloride (RuCl ₃ · 3H ₂ O, 98%) and 5.0 g of the ionic liquid prepared in Synthesis Example 1 were used. Except that Pt-Ru black 100% by weight in the same manner as in Example 1 was prepared. (Yield 99%)

Comparative Example 1: Preparation of Pt Black with Pt Content of 100% by Weight

10.0 g of chloroplatinic acid (H ₂ PtCl ₆ .6H ₂ O, 99%) was added to the deionized water and stirred for 8 hours at room temperature. Subsequently, a solution of sodium hydroxide and sodium borohydride, which is a reducing agent, in demineralized water was added dropwise to the reaction vessel to reduce the solution for 1 hour. Thereafter, the process of refining with demineralized water was repeated, followed by vacuum drying at 80 ° C. to prepare Pt black having a Pt content of 100% by weight. (95% yield)

Comparative Example 2: Preparation of Pt-Ru Black with Pt-Ru Content of 100% by Weight

Pt- was prepared in the same manner as in Comparative Example 1 except that 10.0 g of chloroplatinic acid (H ₂ PtCl ₆ 6H ₂ O, 99%) and 4.94 g of ruthenium chloride (RuCl ₃ · 3H ₂ O, 98%) were used as the reaction vessel. Pt-Ru black having a Ru content of 100% by weight was prepared. (96% yield)

Comparative Example 3: Pt / C (Johnson Matthey)

This is a Pt black (Johnson Matthey) commercial catalyst with a platinum content of 100% by weight (based on metal).

Comparative Example 4: Pt-Ru Black (Johnson Matthey)

This is a Pt-Ru black (Johnson Matthey) commercial catalyst whose content is 100% by weight (based on metal) of platinum-ruthenium (atomic ratio 1: 1).

In the manufacturing process of Comparative Examples 1 to 2, since the reduction process is performed without a reducing agent serving as a stabilizer of the active metal, catalyst particles are formed larger than those of Examples 1 and 2 corresponding thereto.

Table 2 shows the supported amount of the active metal component, the particle size of the active metal component, the atomic ratio of the active metal component, the weight percentage of the element according to EDX for the catalyst according to Examples 1 to 2 and the catalyst according to Comparative Examples 1 to 4 , And yield and current density values are summarized.

TABLE 2

division Catalyst Name Active metal
Loading
(weight%) Active metal
Average particle size
(nm) atom
ratio EDX
(weight%) Yield
(%) Current density
(id, A / g) Example 1 Pt 100 4.5 - Pt (100) 99 4.8 Example 2 Pt-Ru 100 3.4 1: 1 Pt (66), Ru (34) 99 32 Comparative Example 1 Pt 100 7.2 - Pt (100) 95 2.7 Comparative Example 2 Pt-Ru 100 4.4 1: 1 Pt (66), Ru (34) 96 15 Comparative Example 3 Pt (JM) 100 6.8 - Pt (100) - 3.2 Comparative Example 4 Pt-Ru (JM) 100 4.0 1: 1 Pt (66), Ru (34) - 23

As shown in Table 2, the particle size of the active metal in the supported catalyst according to Example 1 is smaller than the particle size of the commercial catalyst according to Comparative Example 3. Example 1 (platinum particles 4.5nm) has a smaller platinum particle size than Comparative Example 1 (platinum particles 7.2nm) and commercial catalyst Comparative Example 3 (platinum particles 6.8nm), confirming that the particles are evenly distributed. It was. In addition, it was confirmed that Example 2 (platinum-ruthenium alloy particles 3.4nm) also has a smaller size of platinum-ruthenium alloy particles compared to Comparative Example 2 (platinum-ruthenium alloy particles 4.4nm).

In Table 2, the composition, physical properties and current density of the catalysts according to Examples 1 to 2 and Comparative Examples 1 to 4 were evaluated as follows.

Furtherance

The component content was evaluated by SEM-EDX (model name: JEOL, JSM-6335F, measured at 200 kV), and the chemical state of the composition was investigated by XPS (model name: MultiLab.ESCA 2000, light source: Mg Kα, measured at 15 kV / 500 W). It was.

Properties (particle size of catalyst metals)

XRD (model name: Rigaku X-ray powder diffractometer, light source: Cu Kα, measured at 40 kV / 40 mA) was performed to determine the crystallinity and crystal size of the catalyst. The particle size of the catalyst metal was calculated from the platinum (220) peak of the XRD pattern using the Scherrer equation of Equation 1 below, and the results are shown in Table 1 above. In Equation 1 below, L = average particle size, λ _Kα1 = wavelength of X-rays, θB = (θ) value of (220) peak, and B _(2θ) = (θ) range of (220) peak.

[Equation 1]

Current density

The electrical activity was evaluated by measuring the current density per unit weight in the following manner. The catalyst slurry was prepared by mixing 16 mg of the catalyst prepared in Examples 1 to 2 and Comparative Examples 1 to 4, 0.5 ml of 10 wt% Nafion solution, and 20 ml of tertiary distilled water to prepare a catalyst slurry, followed by 2 mm round GC. 3 μl of the prepared catalyst slurry was applied to the electrode. The performance of the half cell electrode was evaluated using a three-electrode system (Reference Electrode: Ag, AgCl / KCl (sat'd), Counter Electrode: Platinum, gauze, 100mesh, 99.9%, in a mixed solution of 0.2M methanol and 0.1M sulfuric acid solution). Electrode: GC Electrode) was carried out at 25 ℃, the injection rate was 20 ㎷ / sec.

Table 2 shows the results. As shown in Table 1, Example 1 (4.8 A / g) using platinum has improved current density compared to Comparative Example 1 (2.7 A / g) and Comparative Example 3 (3.2 A / g), which is a commercial catalyst. Example 2 (32 A / g) using an alloy of platinum and ruthenium showed improved current density compared to Comparative Example 2 (15 A / g) and Comparative Example 4 (23 A / g), which is a commercial catalyst.

In order to compare the performance of the fuel cell employing the catalysts of Examples 1 and 2 and the fuel cells using the catalysts of Comparative Examples 3 and 4, which are commercial catalysts, fuel cells were prepared as in the following Production Examples.

Production Example

A binder such as polytetrafluoroethylene or Nafion solution, or a microporous layer containing ionomer and conductive carbon material is sprayed onto a water-repellent carbon paper with a fluorine resin such as polytetrafluoroethylene. After introducing the gas diffusion layer to prepare a cathode electrode by mixing the catalyst of Example 1 and a small amount of Nafion solution by spraying, the anode electrode was configured by applying the catalyst of Example 2 in the same manner. .

Subsequently, a conductive polymer film (Nafion 115-manufacturer: DuPont) was placed between the positive electrode and the negative electrode, and then a membrane electrode assembly (MEA) was manufactured by a thermal pressure method. A unit cell system was constructed by introducing a separator plate for supplying fuel (methanol) to the cathode side and a separator plate for supplying gas (air) to the anode side. The fuel supply of the fuel supply separation plate was supplied using a fuel pump in the fuel reservoir, the gas supply of the gas supply separation plate was supplied using an air pump, and the performance of the manufactured fuel cell was evaluated at room temperature.

On the other hand, in order to compare the performance of the fuel cell employing the supported catalysts of Examples 1 and 2 and the fuel cell using the supported catalysts of Comparative Examples 3 and 4, which are commercial catalysts, the catalyst according to Comparative Example 5, which is a commercial catalyst on the anode, was used. Except for using the catalyst according to Comparative Example 4 which is a commercial catalyst for the negative electrode, the same fuel cell system as described above was produced and its performance was evaluated.

2 shows performance evaluation results of a unit cell using the catalysts according to Examples 1 and 2 and a fuel cell using the catalysts according to Comparative Examples 3 and 4. FIG.

As shown in Figure 2, when comparing the performance under the same conditions it can be seen that in the case of the embodiment the power density per unit area is higher than the comparative example, and thus an embodiment of the present invention compared to the conventional known commercial catalyst It can be seen that the catalyst produced by the production method according to the present invention exhibits an excellent performance increase effect when employed as an electrode material of a fuel cell.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

1 is a view showing a fuel cell according to an embodiment of the present invention.

2 is a graph measuring power density and voltage according to current of the catalysts according to Examples 1 and 2 and the catalysts according to Comparative Examples 3 and 4;

<Short description of drawing symbols>

20: anode 30: cathode

40: electrolyte membrane 50: anode separator

60: cathode separator 22: anode diffusion layer

21: anode catalyst layer 31: cathode catalyst layer

32: cathode diffusion layer

110: carbon-based support 120: metal oxide particles

130: catalytic metal particles

Claims (14)

Preparing a metal precursor mixed solution comprising a main catalyst metal precursor and an ionic liquid; Reducing the metal precursor mixed solution with a reducing agent to prepare a reduction product; Purifying the reduction product and recovering the ionic liquid; And Method for producing a catalyst for a fuel cell comprising the step of drying the purified result. The method of claim 1, wherein the main catalyst metal precursor is a chloride, nitride, oxide or halide of platinum. The method according to claim 1, wherein the main catalyst metal precursor is tetrachloroplatinic acid (H ₂ PtCl ₄ ), hexachloroplatinic acid (H ₂ PtCl ₆ ), tetrachloroplatinic acid potassium (K ₂ PtCl ₄ ), hexachloroplatinum potassium (K ₂ PtCl ₆ ), Pt (NH ₃ ) ₂ (NO ₂ ) ₂ , and Pt (NH ₃ ) ₄ Cl _{2 A} method for producing a catalyst for a fuel cell, characterized in that at least one selected from the group consisting of. The method of claim 1, wherein the mixed metal precursor solution further comprises a cocatalyst metal precursor. The method of claim 4, wherein the cocatalyst metal precursor is at least one metal selected from the group consisting of cerium, ruthenium, tin, tungsten, titanium, molybdenum, iron, vanadium, manganese, cobalt, chromium, nickel, palladium, rhodium and iridium. A method for producing a catalyst for a fuel cell, characterized in that the chloride, nitride, oxide or halide. The method according to claim 4, wherein the cocatalyst metal precursor is (NH ₄ ) ₂ [RuCl ₆ ], (NH ₄ ) ₂ [RuCl ₅ H ₂ 0], RuCl ₃ .3H ₂ O, (CH ₃ COO) ₂ Co. A method for producing a catalyst for a fuel cell, characterized in that at least one selected from the group consisting of 4H ₂ O, CoCl ₂ · 6H ₂ O, CoSO ₄ · 7H ₂ O, CoF ₂ and Co (NO ₃ ) ₂ · 6H ₂ O. According to claim 1, wherein the ionic liquid is a salt consisting of a cation and an anion, the cation is selected from the formula of Table 1, the anion is a group VIII, IB, 2B, IIIA, VA on the periodic table (CAS version) Process for producing a catalyst for a fuel cell, characterized in that the halide, alkylsulfonyl, haloalkylsulfonyl, phosphoryl, imide, nitrate or carbonyl group of the element of: TABLE 1

In Table 1, R, R ', and R "are independently a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms. The method of claim 1, wherein the ionic liquid is 1-ethyl-3-methyl-imidazolium (EMIM), 1-methyl-3-propyl-imidazoli 윰 ( 1-methyl-3-propyl-imidazolium (PMIM), 1-butyl-3-methyl-imidazolium (BMIM), 1-methyl-3-pentyl-imidazoli 1- (1-methyl-3-pentyl-imidazolium (PnMIM), 1-hexyl-3-methyl-imidazolium (HMI)), 1- and heptyl-3-methyl- Cation selected from the group consisting of 1-heptyl-3-methyl-imidazolium (HpMIM), and hexafluoroantimonate (SbF ₆ ), hexafluorophosphate (PF ₆ ), tetrafluoroborate ( BF ₄ ), bis (trifluorosulfonyl) imide (NTf ₂ ), trifluoromethanesulfonate (OTf), acetate (OAc), and nitrate (NO ₃ ) containing anions selected from the group Production of a catalyst for a fuel cell, characterized in that the imidazolysin salt Way. The catalyst for a fuel cell of claim 1, further comprising: adding a carbon support to the metal precursor mixture solution and stirring the metal precursor mixture solution before reducing the metal precursor mixture solution with a reducing agent to produce a reduction product. Manufacturing method. The method of claim 9, wherein the carbon support is carbon black, Ketjen black, acetylene black, activated carbon powder, carbon molecular sieve, carbon nanotubes, activated carbon having fine pores, mesoporous carbon, or a mixture thereof A method for producing a catalyst for a fuel cell. The method of claim 1, wherein the reducing agent is at least one selected from the group consisting of alcohols, hydrazines, aldehydes, sodium borohydride, lithium borohydride, potassium borohydride, sodium thiosulfate, and the like. A fuel cell electrode comprising a catalyst prepared according to any one of claims 1 to 11. Membrane electrode assembly comprising an electrode according to claim 12. A fuel cell comprising the membrane electrode assembly of claim 13.

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