KR100551034B1 - Catalist for fuel cell, preparation method thereof, and fuel cell system comprising the same - Google Patents

Abstract

The present invention relates to a catalyst for a fuel cell, a method for manufacturing the same, and a fuel cell system including the same. More specifically, a catalyst for a fuel cell having an oxide reduction potential (ORP) of platinum (Pt) of 450 mV or more, and a production thereof It relates to a method and a fuel cell system comprising the same.

The catalyst for a fuel cell of the present invention has the advantage of improving the speed performance of the entire fuel cell system while reducing the production cost and having a high oxygen reduction rate of platinum and excellent reactivity.

Fuel cell, platinum, iron, alloy, heat treatment, oxygen reduction potential, cyclic ammeter

Description

Catalyst for fuel cell, method of manufacturing the same, and fuel cell system including same {CATALIST FOR FUEL CELL, PREPARATION METHOD THEREOF, AND FUEL CELL SYSTEM COMPRISING THE SAME}

1 is a schematic diagram of a platinum-oxygen adsorption model of a catalyst for a fuel cell of the present invention.

2 is a schematic diagram showing an overall configuration of a fuel cell system of the present invention.

3 is an exploded perspective view showing a stack of the fuel cell system of the present invention.

4 is a graph showing Oxygen Reduction Potential (ORP) values of catalysts for fuel cells prepared according to Examples 1 to 8 and Comparative Examples 1 to 7. FIG.

5 is a cyclic voltametry (CV) graph of the catalyst for fuel cells prepared according to Examples 1 and 2. FIG.

6 is a graph showing a cyclic voltametry (CV) graph of a catalyst for a fuel cell prepared according to Examples 3 and 4. FIG.

7 is a graph showing a cyclic voltametry (CV) graph of a catalyst for a fuel cell prepared according to Examples 5 and 6. FIG.

8 is a graph showing a cyclic voltametry (CV) graph of a catalyst for a fuel cell prepared according to Examples 7 and 8. FIG.

9 is a graph of cyclic voltametry (CV) of a catalyst for a fuel cell prepared according to Comparative Examples 1 to 3. FIG.

10 is a graph of the cyclic voltametry (CV) of the catalyst for fuel cells prepared according to Comparative Examples 4 and 5.

[Industrial use]

The present invention relates to a fuel cell catalyst, a method for manufacturing the same, and a fuel cell system including the same. More particularly, the present invention relates to a fuel cell catalyst, a method for producing the same, and a fuel cell system including the same.

[Private Technology]

In general, a fuel cell is a power generation that directly converts chemical energy into electrical energy by an electrochemical reaction generated by using hydrogen, oxygen, or oxygen-containing air as a fuel contained in a hydrocarbon-based material such as methanol, ethanol, or natural gas. System.

These fuel cells are phosphoric acid fuel cells operating near 150 ~ 200 ℃, molten carbonate fuel cells operating at high temperature of 600 ~ 700 ℃, solid oxide type operating at high temperature of 1000 ℃ or higher depending on the type of electrolyte used. It is classified into fuel cell, polymer electrolyte type and alkaline type fuel cell operating at room temperature to below 100 ° C. Each of these fuel cells operates on the same principle, but the type of fuel, operating temperature, catalyst and electrolyte Are different.

Among these, polymer electrolyte fuel cells (PEMFCs), which are being developed recently, have excellent output characteristics, low operating temperatures, fast start-up and response characteristics compared to other fuel cells, and methanol and ethanol. In addition, using hydrogen produced by reforming natural gas as a fuel has a wide range of applications such as a mobile power source such as a car, a distributed power source such as a house and a public building, and a small power source such as an electronic device.

In order for the polymer electrolyte fuel cell as described above to basically have a system configuration, a fuel cell body (hereinafter referred to as a stack for convenience) called a stack, a fuel tank, and a fuel tank are supplied from the fuel tank to the stack. A fuel pump for this purpose is needed. Further, a reformer for reforming the fuel to generate hydrogen gas and supplying the hydrogen gas to the stack is further included in the process of supplying the fuel stored in the fuel tank to the stack. Therefore, the polymer electrolyte fuel cell supplies the fuel stored in the fuel tank to the reformer by the pumping force of the fuel pump, the reformer reforms the fuel to generate hydrogen gas, and the stack electrochemically reacts the hydrogen gas with oxygen. Electric energy is produced.

On the other hand, the fuel cell may employ a direct methanol fuel cell (DMFC) method that can supply the liquid methanol fuel directly to the stack. Such a direct methanol fuel cell fuel cell, unlike the polymer electrolyte fuel cell, the reformer is excluded.

In the fuel cell system as described above, a stack that substantially generates electricity has a structure in which several to tens of unit cells composed of an electrode-electrolyte assembly (MEA) and a bipolar plate are stacked. Has The electrode-electrolyte composite has a structure in which an anode electrode (also called "fuel electrode" or "oxide electrode") and a cathode electrode (also called "air electrode" or "reduction electrode") are attached with an electrolyte membrane interposed therebetween. . The bipolar plate simultaneously serves as a passage for supplying hydrogen gas and oxygen necessary for the reaction of the fuel cell and a conductor connecting the anode electrode and the cathode electrode of each electrode-electrolyte composite in series. Therefore, hydrogen gas is supplied to the anode electrode by the bipolar plate, while oxygen is supplied to the cathode electrode. In this process, electrochemical oxidation of hydrogen gas occurs at the anode electrode, and electrochemical reduction of oxygen occurs at the cathode electrode, and electricity, heat, and water can be obtained together due to the movement of the generated electrons.

Here, the catalyst used in the oxygen reduction reaction of the cathode is mainly used platinum (Pt), because the price of platinum is expensive, various alloy catalysts have been studied.

U.S. Patent No. 4447506 describes alloy catalysts such as platinum (Pt)-chromium (Cr)-cobalt (Co), platinum (Pt)-chromium (Cr), and U.S. Pat. Contents relating to alloy catalysts such as Pt) -gallium (Ga) and platinum (Pt) -chromium (Cr) are described. However, the patent document does not clearly indicate how the bonding force between the platinum and the oxygen affects the oxygen reduction reaction and is related to the overall activity of the catalyst, and much research is required.

The present invention is to solve the above problems, an object of the present invention is to increase the speed of the oxygen reduction reaction by controlling the bonding force between the platinum and oxygen, to increase the speed of the overall fuel cell chemical reaction catalyst for fuel cells To provide.

Another object of the present invention is to provide a method for preparing the fuel cell catalyst.

Still another object of the present invention is to provide a fuel cell system including the catalyst for the fuel cell.

In order to achieve the above object, the present invention provides a catalyst for a fuel cell having an oxide reduction potential (ORP) of platinum (Pt) of 450 mV or more.

The invention also comprises the steps of mixing the platinum-containing material and iron-containing material to prepare a mixture; Drying the mixture; And it provides a method for producing a catalyst for a fuel cell comprising the step of heat-treating the dried mixture.

The invention also comprises the steps of mixing a platinum containing material, a chromium containing material and a nickel containing material to prepare a mixture; Drying the mixture; And it provides a method for producing a catalyst for a fuel cell comprising the step of heat-treating the dried mixture.

The present invention also provides a fuel supply unit for supplying a fuel mixed with fuel and water; A reforming unit reforming the mixed fuel to generate hydrogen gas; A stack comprising the catalyst for the fuel cell, wherein the hydrogen gas supplied from the reforming unit undergoes an electrochemical reaction with external air to generate electrical energy; And an air supply unit supplying external air to the stack and the reforming unit.

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

The chemical reaction of the fuel cell of the present invention is developed in the following reaction.

^{_{Cathode: O 2 + 4H + + 4e}} - → 2H 2 O

^{_{Anode: H 2 → 2H + + 2e}} -

Total: 2H ₂ + O ₂ → 2H ₂ O

In the above scheme, the oxygen reduction reaction of the cathode corresponds to the rate determining step (rds), and the detailed mechanism of the oxygen reduction reaction, which is the rate determining step reaction, has not yet been elucidated.

However, while oxygen is adsorbed on the platinum surface with moderate force, hydrogen approaches the platinum surface and reacts with the adsorbed oxygen to estimate that oxygen is released from the platinum surface to make water. The intensity of oxygen adsorption is related to the reaction rate, and thus, the reaction rate of fuel cell chemistry is closely related to the bonding force between platinum and oxygen.

1 is a diagram schematically showing a platinum-oxygen adsorption model in the catalyst for a fuel cell of the present invention containing a platinum-iron alloy. As shown in FIG. 1, there are various kinds of platinum-oxygen adsorption models, among which the bridge model is most likely. However, in any of the models shown in FIG. 1, the bonding force between the platinum and the oxygen affects the fuel cell chemical reaction mechanism.

The catalyst for fuel cells of the present invention has an oxygen reduction potential (ORP) of platinum (Pt) of 450 mV or more, preferably 450 to 550 mV, and more preferably 450 to 520 mV. If the oxygen reduction potential is less than 450 mV, the overall fuel cell chemistry is slow. However, in the case of 550mV or more, the particle size of the catalyst may increase.

The oxygen reduction potential (ORP) refers to the maximum value of the peak appearing between 300 mV to 600 mV when performing a cyclic voltametry (CV) experiment, the oxygen reduction potential value in the present invention Saturated calomel electrode (SCE) is used as a standard electrode, 10 wt% polytetrafluoroethane (PTFE) binder is used as a catalyst for fuel cells, and a paste electrode is used. A platinum plate is used as a counter electrode. 1 MH ₂ Based on an aqueous solution of SO ₄ as an electrolyte, measured at a scan rate of 10 mV / sec.

In general, in the case of a carbon-supported platinum (Pt / C) catalyst, which is the most commonly used catalyst for fuel cells, the oxygen reduction potential of platinum is lower than 450 mV. The larger the oxygen reduction potential value of platinum, the easier it is to be electrochemically reduced. In other words, oxygen is adsorbed on the surface of platinum during the oxygen reduction reaction of the cathode, which is a rate determining step, during the chemical reaction of the fuel cell, and the adsorbed oxygen is reduced and then falls off again. Means easier and faster reduction, which means that the activity of the catalyst is greater.

Thus, having a higher oxygen reduction potential means that the performance of the catalyst is better and also contributes to the improvement of the overall fuel cell performance.

The fuel cell catalyst includes a platinum-iron alloy, a platinum-chromium-nickel alloy, or a mixture thereof. The content of iron contained in the platinum-iron alloy is preferably 0.3 to 1.2 moles with respect to 1 mole of platinum. If the iron content is less than 0.3 mole with respect to 1 mole of platinum, it is difficult to form an alloy. When the iron content is more than 1.2 mole, it is difficult to obtain an effect of improving the oxygen reduction potential by the alloy. In addition, the platinum-chromium-nickel alloy preferably has a sum of chromium and nickel of 0.3 to 1.2 moles with respect to 1 mole of platinum. When the sum of chromium and nickel is less than 0.3 mole with respect to 1 mole of platinum, alloy formation is difficult. When the molar amount exceeds 1.2 mole, the effect of improving the oxygen reduction potential by the alloy is hardly obtained. In this case, however, in the platinum-chromium-nickel alloy, the molar ratio of chromium and nickel is preferably 4: 6 to 6: 4.

In the fuel cell catalyst, the average particle diameter of the alloy catalyst particles excluding the carrier is preferably 30 to 150 mm 3, more preferably 30 to 100 mm 3. The smaller the particle size of the catalyst is better, but if it is less than 30 kPa, there is difficulty in manufacturing, and if it exceeds 150 kPa, the reaction surface area is too small, so it is not practical and requires a high heat treatment temperature.

Among the catalysts for fuel cells of the present invention, the catalyst comprising a platinum-iron alloy may be prepared from a platinum-containing material and an iron-containing material, and more specifically, mixing the platinum-containing material and the iron-containing material to prepare a mixture; Drying the mixture; Heat-treating the dried mixture.

At this time, it is preferable that the iron-containing material and the platinum-containing material are mixed so that the iron content per mole of platinum is 0.3 to 1.2 moles. When the content ratio of the iron-containing material is less than 0.3 mole based on the iron content of 1 mole of platinum, it is difficult to obtain the effect of improving the oxygen reduction potential by the alloy, and when it exceeds 1.2 moles, it is difficult to form the alloy.

The platinum-containing material may use platinum supported on a carrier commonly used in fuel cells. Specific examples of the carrier include carbon, alumina, silica, and the like. Of these, preferably platinum supported using carbon as a carrier can be used, and in this case, the carbon is more preferably acetylene black, graphite or the like.

Platinum supported by the carrier may be commercially available, or may be used by supporting platinum on the carrier. The process of supporting platinum on the carrier is well known in the art, and thus detailed description thereof will be omitted.

In addition, the iron-containing material includes iron, any compound that can form an alloy of platinum and iron may be used, but preferably a metal halide, nitrate, hydrochloride, sulfate or amine containing iron One or more may be used, and more preferably, metal halides containing iron may be used.

The iron-containing material may be mixed and used in a liquid phase, and preferably, the iron-containing material may be used in a solution state in which alcohol, water, or a mixture of alcohol and water is dissolved. The solution preferably has a concentration of iron-containing material in the range of 0.1 to 1 M.

After the mixture is prepared by mixing the platinum-containing material and the iron-containing material, it is dried. The drying process is a process of evaporating the water contained in the mixture, according to a conventional drying process.

After drying the mixture, the heat treatment is performed, and the heat treatment is preferably performed at a temperature of 500 ° C. or higher in a reducing atmosphere, more preferably the heat treatment temperature is 700 to 1500 ° C., and the heat treatment temperature is 700 Most preferably, it is -1000 degreeC. If the heat treatment temperature is less than 500 ° C., alloy formation is difficult. In addition, when the heat treatment temperature exceeds 1500 ° C, since the transition metal vaporization may occur, it is difficult to manufacture the alloy of the correct ratio.

In the reducing atmosphere during the heat treatment, a hydrogen gas, a nitrogen gas, or a mixed gas of hydrogen and nitrogen may be used.

Among the catalysts for fuel cells of the present invention, the catalyst comprising a platinum-chromium-nickel alloy can be prepared from a platinum containing material, a chromium containing material and a nickel containing material, and more particularly, a platinum containing material, a chromium containing material and a nickel containing material. Mixing the materials to prepare a mixture; Drying the mixture; Thermally treating the dried mixture.

At this time, the platinum-containing material, chromium-containing material and nickel-containing material are preferably mixed so that the sum of chromium and nickel is 0.3 to 1.2 moles with respect to 1 mole of platinum. When the content of chromium and nickel is less than 0.3 mole with respect to 1 mole of platinum, it is difficult to obtain an effect of improving the oxygen reduction potential by the alloy, and when it exceeds 1.2 moles, it is difficult to form an alloy. In this case, however, the relative mixing ratio of the chromium-containing material and the nickel-containing material is preferably 4: 6 to 6: 4 based on the molar ratio of chromium and nickel.

The platinum-containing material may use platinum supported on a carrier commonly used in fuel cells. Specific examples of the carrier include carbon, alumina, silica, and the like. Of these, preferably platinum supported using carbon as a carrier can be used, and in this case, the carbon is more preferably acetylene black, graphite or the like.

In addition, the chromium-containing material may be used as long as it contains a chromium, and any compound capable of forming an alloy with platinum, preferably a metal halide, nitrate, hydrochloride, sulfate or amine containing chromium. The above may be used, and more preferably, nitrate containing chromium may be used.

In addition, the nickel-containing material may be any compound as long as it contains nickel and may form an alloy with platinum. Preferably, the metal halide, nitrate, hydrochloride, sulfate, amine, etc. containing nickel may be used. It may be used as described above, and more preferably, metal halides containing nickel may be used.

The chromium-containing material and the nickel-containing material may be mixed and used in a liquid phase, and preferably, the chromium-containing material and the nickel-containing material may be used in a solution state in which alcohol, water, or a mixture of alcohol and water is dissolved. The solution preferably has a concentration of chromium-containing material and nickel-containing material of 0.1 to 1 M, respectively.

After the mixture is prepared by mixing the platinum-containing material, the chromium-containing material and the nickel-containing material, it is subjected to drying and heat treatment. The drying process is a process of evaporating a solvent, such as water and alcohol, included in the mixture, according to a conventional drying process.

After drying the mixture, the heat treatment is performed, and the heat treatment is preferably performed at a temperature of 500 ° C. or higher in a reducing atmosphere, more preferably the heat treatment temperature is 700 to 1500 ° C., and the heat treatment temperature is 700 Most preferably, it is -1000 degreeC. If the heat treatment temperature is less than 500 ° C., alloy formation is difficult. In addition, when the heat treatment temperature exceeds 1500 ° C, since the transition metal vaporization may occur, it is difficult to manufacture the alloy of the correct ratio.

In the reducing atmosphere during the heat treatment, a hydrogen gas, a nitrogen gas, or a mixed gas of hydrogen and nitrogen may be used.

2 is a schematic diagram showing the overall configuration of the fuel cell system 100 of the present invention, Figure 3 is an exploded perspective view showing a stack 130 of the fuel cell system of the present invention.

2 and 3, the fuel cell system 100 of the present invention includes a fuel supply unit 110 for supplying a mixed fuel in which fuel and water are mixed; A reforming unit for reforming the mixed fuel to generate hydrogen gas; A stack 130 including the catalyst for the fuel cell, wherein the hydrogen gas supplied from the reforming unit undergoes an electrochemical reaction with external air to generate electrical energy; And an air supply unit 140 supplying external air to the reforming unit 120 and the stack 130.

In addition, the stack 130 of the fuel cell system of the present invention includes a plurality of unit cells for generating electrical energy by inducing an oxidation / reduction reaction of hydrogen gas supplied from the reforming unit 120 and external air supplied from the air supply unit ( 131.

Each unit cell 131 refers to a cell of a unit for generating electricity, and includes an electrolyte-electrode assembly (MEA) 132 for oxidizing / reducing hydrogen gas and oxygen in air. A separator (also called a bipolar plate, hereinafter referred to as a "bipolar plate") 133 for supplying air to the electrolyte-electrode composite 132. The separator 133 has the electrolyte-electrode complex 132 at the center and is disposed at both sides thereof. At this time, the separator plates located at the outermost side of the stack may be specifically referred to as end plates 133a.

The electrolyte-electrode complex 132 has a structure in which an electrolyte membrane is interposed between the anode electrode and the cathode electrode forming both sides.

The anode electrode is a portion receiving hydrogen gas through the separator 133, a catalyst layer for converting hydrogen gas into electrons and hydrogen ions by an oxidation reaction, and a gas diffusion layer (GDL: Gas) for smooth movement of electrons and hydrogen ions. Diffusion Layer).

In addition, the cathode electrode is a portion that receives air through the separator 133, the catalyst layer for the fuel cell converts oxygen in the air into electrons and oxygen ions by a reduction reaction, and a gas for smooth movement of electrons and oxygen ions It consists of a diffusion layer. The electrolyte membrane is a solid polymer electrolyte having a thickness of 50 to 200 μm, and has an ion exchange function for transferring hydrogen ions generated in the catalyst layer of the anode electrode to the catalyst layer of the cathode electrode.

In addition, the end plate 133a of the separation plate includes a pipe-shaped first supply pipe 133a1 for injecting hydrogen gas supplied from the reforming unit and a pipe-shaped second supply pipe 133a2 for injecting oxygen gas. And a first discharge pipe 133a3 for discharging the remaining unreacted hydrogen gas to the outside in the other end plate 133a and the unit cell 131. Finally, a second discharge pipe 133a4 for discharging the unreacted and remaining air to the outside is provided.

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

EXAMPLE

Example 1

Johnson Matthey Co. commercial platinum / carbon (Pt / C) catalyst (10 wt% platinum) was mixed and dispersed in an aqueous solution of 1.0 M FeCl ₂ concentration. At this time, the platinum / carbon (Pt / C) catalyst and the content of FeCl ₂ were set to 1: 1 based on the molar ratio of platinum: iron.

After the mixing process, the mixture was dried at 100 ° C. for 1 hour, and then heat-treated at 700 ° C. for 2.5 hours in the presence of a mixed gas of hydrogen and nitrogen (10% by volume of hydrogen and 90% by volume of nitrogen) to prepare a catalyst for a fuel cell.

Example 2

A catalyst for a fuel cell was prepared in the same manner as in Example 1 except that the heat treatment temperature was 900 ° C.

Example 3

The content of platinum / carbon (Pt / C) catalyst and FeCl ₂ was 3: 1 based on the molar ratio of platinum: iron, and the fuel cell was manufactured in the same manner as in Example 1 except that the heat treatment temperature was 700 ° C. Catalyst was prepared.

Example 4

The content of platinum / carbon (Pt / C) catalyst and FeCl ₂ is 3: 1 based on the molar ratio of platinum: iron and the heat treatment temperature is 900 ° C. for the fuel cell. Catalyst was prepared.

Example 5

Johnson Matthey Co.'s commercial platinum / carbon (Pt / C) catalyst (platinum content 10% by weight) was mixed with a 1 M mixed solution of Cr (NO ₃ ) ₃ · 9H ₂ O and NiCl ₂ . Dispersed. At this time, the contents of the platinum / carbon (Pt / C) catalyst, Cr (NO ₃ ) ₃ .9H ₂ O and NiCl ₂ were set to be 2: 1: 1 based on the molar ratio of platinum: chromium: nickel.

After the mixing process, the mixture was dried at 100 ° C. for 1 hour, and then heat-treated at 700 ° C. for 2.5 hours in the presence of a mixed gas of hydrogen and nitrogen (10% by volume of hydrogen and 90% by volume of nitrogen) to prepare a catalyst for a fuel cell.

Example 6

A fuel cell catalyst was prepared in the same manner as in Example 5 except that the heat treatment temperature was 900 ° C.

Example 7

The content of platinum / carbon (Pt / C) catalyst, Cr (NO ₃ ) ₃ · 9H ₂ O and NiCl ₂ should be 6: 1: 1 based on the molar ratio of platinum: chromium: nickel, and the heat treatment temperature is 700 ℃. A catalyst for a fuel cell was manufactured in the same manner as in Example 5 except for setting it as described above.

Example 8

The content of platinum / carbon (Pt / C) catalyst, Cr (NO ₃ ) ₃ · 9H ₂ O and NiCl ₂ should be 6: 1: 1 based on the molar ratio of platinum: chromium: nickel and the heat treatment temperature is 900 ° C. A catalyst for a fuel cell was manufactured in the same manner as in Example 5 except for setting it as described above.

Comparative Example 1

Johnson Matthey Co.'s platinum / carbon (Pt / C) catalyst (platinum content 10 wt%) was used as a catalyst for fuel cells.

Comparative Example 2

Johnson Matthey Co.'s platinum / carbon (Pt / C) catalyst (platinum content 10% by weight) was heated to 400 ° C in the presence of a mixture of hydrogen and nitrogen (10% by volume hydrogen and 90% by volume nitrogen). Heat treatment for 2.5 hours to prepare a catalyst for a fuel cell.

Comparative Example 3

A catalyst for a fuel cell was prepared in the same manner as in Comparative Example 1 except that the heat treatment temperature was 500 ° C.

Comparative Example 4

Johnson Matthey Co. commercial platinum / carbon (Pt / C) catalyst (10 wt% platinum) was mixed and dispersed in an aqueous solution of 1.0 M NiCl ₂ concentration. At this time, the content of the platinum / carbon (Pt / C) catalyst and the nickel-containing material was set to 1: 1 based on the molar ratio of platinum: nickel.

After the mixing process, the mixture was dried at 100 ° C. for 1 hour, and then heat-treated at 700 ° C. for 2.5 hours in the presence of a mixed gas of hydrogen and nitrogen (10% by volume of hydrogen and 90% by volume of nitrogen) to prepare a catalyst for a fuel cell.

Comparative Example 5

A catalyst for a fuel cell was prepared in the same manner as in Comparative Example 1 except that the heat treatment temperature was 900 ° C.

Comparative Example 6

The content of platinum / carbon (Pt / C) catalyst and NiCl ₂ should be 3: 1 based on the molar ratio of platinum: nickel and the same as in Example 1 except that the heat treatment temperature was 700 ° C. Catalyst was prepared.

Comparative Example 7

The content of platinum / carbon (Pt / C) catalyst and NiCl ₂ is 3: 1 based on the molar ratio of platinum: nickel, and the fuel cell is manufactured in the same manner as in Example 1 except that the heat treatment temperature is 900 ° C. Catalyst was prepared.

The fuel cell catalysts prepared according to Examples 1 to 8 and Comparative Examples 1 to 7 were mixed with 10% by weight of polytetrafluoroethane (PTFE) binder to form a paste electrode, and a platinum plate was used as a counter electrode. The oxygen reduction potential of platinum of each catalyst was measured by a cyclic current method using a 1 MH ₂ SO ₄ aqueous solution as an electrolyte and a saturated calorie electrode (SCE) as a standard electrode. At this time, the scanning speed was 10 mV / sec.

Figure 4 is a graph showing the oxygen reduction potential (ORP) value of the catalyst for fuel cells prepared according to Examples 1 to 8 and Comparative Examples 1 to 7 measured by the above method. 5, 6, 7 and 8 are cyclic currents of a catalyst for a fuel cell prepared according to Examples 1, 2, 3, 4, 5, 6 and 7, respectively. Voltametry (CV) is a graph, Figure 9 is Comparative Examples 1 to 3, Figure 10 is a cyclic voltametry (CV) graph of the catalyst for a fuel cell prepared according to Comparative Examples 4 and 5.

The oxygen reduction potential values shown in FIG. 4 are summarized in Table 1 below.

TABLE 1

Alloy components Alloy composition ratio Heat treatment temperature (℃) Catalyst particle size Redox potential (mV) Example 1 Pt-Fe 1: 1 700 86.2 503 Example 2 Pt-Fe 1: 1 900 108 506 Example 3 Pt-Fe 3: 1 700 55.4 474 Example 4 Pt-Fe 3: 1 900 55 474 Example 5 Pt ₂ -Cr-Ni 2: 1: 1 700 44.7 484 Example 6 Pt ₂ -Cr-Ni 2: 1: 1 900 54 502 Example 7 Pt ₆ -Cr-Ni 6: 1: 1 700 48.4 464 Example 8 Pt ₆ -Cr-Ni 6: 1: 1 900 49.7 489 Comparative Example 1 Pt - No heat treatment <20 449 Comparative Example 2 Pt - 400 31.5 431 Comparative Example 3 Pt - 500 32.2 434 Comparative Example 4 Pt-Ni 1: 1 700 56.9 434 Comparative Example 5 Pt-Ni 1: 1 900 74.7 444 Comparative Example 6 Pt-Ni 3: 1 700 46.2 400 Comparative Example 7 Pt-Ni 3: 1 900 63.5 417

As shown in Table 1, the catalyst for a fuel cell of the present invention has a higher oxygen reduction potential value and is more easily electrochemically reduced than a platinum (Pt / C) catalyst supported on carbon, which is commonly used. It can be seen that the activity is greater.

The catalyst for a fuel cell of the present invention has a low production cost and has a high oxygen reduction rate and excellent reactivity of platinum, thereby improving the speed performance of the entire fuel cell system.

Claims (25)

A catalyst for a fuel cell having an oxygen reduction potential (ORP) of platinum (Pt) of 450 to 550 mV. delete The catalyst for a fuel cell according to claim 1, wherein the fuel cell catalyst comprises at least one selected from the group consisting of a platinum-iron alloy and a platinum-chromium-nickel alloy. The catalyst for a fuel cell of claim 3, wherein the platinum-iron alloy comprises 0.3 to 1.2 moles of iron per mole of platinum. The catalyst for a fuel cell of claim 3, wherein the platinum-chromium-nickel alloy has a sum of chromium and nickel in an amount of 0.3 to 1.2 moles with respect to 1 mole of platinum. The fuel cell catalyst according to claim 3, wherein the average particle diameter of the alloy catalyst particles excluding the carrier is 30 to 150 mm 3. The catalyst for a fuel cell of claim 3, wherein the platinum-iron alloy or the platinum-chromium-nickel alloy is an alloy heat-treated at 700 ° C or higher. The catalyst of claim 7, wherein the platinum-iron alloy or platinum-chromium-nickel alloy is an alloy heat-treated at 700 ° C to 1500 ° C. Mixing the platinum containing material with the iron containing material to produce a mixture; Drying the mixture; And Heat-treating the dried mixture Including; The iron-containing material is a method for producing a fuel cell catalyst of at least one selected from the group consisting of metal halides, nitrates, hydrochlorides, sulfates and amines containing iron. The method of claim 9, wherein the platinum-containing material and the iron-containing material are mixed so that the iron content is 0.3 to 1.2 moles with respect to 1 mole of platinum. The method of claim 9, wherein the platinum-containing material is at least one selected from the group consisting of platinum supported on carbon, platinum supported on alumina, and platinum supported on silica. delete The method of claim 9, wherein the iron-containing material is in a solution state dissolved in alcohol, water, or a mixture of alcohol and water. The method of claim 13, wherein the solution has a concentration of 0.1 to 1 M of iron-containing material. Mixing the platinum containing material, the chromium containing material and the nickel containing material to prepare a mixture; Drying the mixture; And Heat-treating the dried mixture Including; The chromium-containing material is at least one selected from the group consisting of chromium-containing metal halides, nitrates, hydrochlorides, sulfates and amines, The nickel-containing material is a method for producing a fuel cell catalyst of at least one selected from the group consisting of metal halides, nitrates, hydrochlorides, sulfates and amines containing nickel. The method of claim 15, wherein the platinum-containing material, the chromium-containing material, and the nickel-containing material are mixed so that the sum of the contents of chromium and nickel is 0.3 to 1.2 moles with respect to 1 mole of platinum. The method of claim 15, wherein the platinum-containing material is at least one selected from the group consisting of platinum supported on carbon, platinum supported on alumina, and platinum supported on silica. delete delete The method of claim 15, wherein the chromium-containing material and the nickel-containing material are in a solution state dissolved in alcohol, water, or a mixture of alcohol and water. The method of claim 20, wherein the concentration of the chromium-containing material and the nickel-containing material dissolved in the solution is 0.1 to 1 M, respectively. The method of claim 9, wherein the heat treatment is performed at a temperature of 700 ° C. or higher in a reducing atmosphere. The method of claim 22, wherein the heat treatment temperature is 700 to 1500 ℃. 23. The method of claim 22, wherein the reducing atmosphere is a hydrogen gas, a nitrogen gas, or a mixed gas atmosphere of hydrogen and nitrogen. A fuel supply unit supplying a mixed fuel in which fuel and water are mixed; A reforming unit reforming the mixed fuel to generate hydrogen gas; A stack comprising a catalyst for a fuel cell according to any one of claims 1 to 8, wherein the hydrogen gas supplied from the reforming unit undergoes an electrochemical reaction with external air to generate electrical energy; And A fuel cell system comprising an air supply for supplying external air to the stack and reforming unit.

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