JPH09167620A - ELECTRODE CATALYST FOR FUEL CELL, MANUFACTURING METHOD THEREOF, AND ELECTRODE AND FUEL CELL USING THE CATALYST - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a highly active and long-life fuel cell electrode catalyst that can contribute to the realization of a practical fuel cell with high output and long life. The electrocatalyst of the present invention is a fuel having a conductive carbon powder carrier and metal catalyst particles made of Pt material selected from Pt and Pt alloy and dispersed and carried on the conductive carbon powder carrier. In electrode catalysts for batteries,
On the surface of the metal catalyst particles, Nb, Ni, Sn, Ta, Ti, selected from oxides and hydroxides,
And a compound containing at least one element selected from Zr and Si together. The electrode of the present invention has a conductive and acid-resistant support member,
In a fuel cell electrode in which an electrode catalyst layer composed of an electrode catalyst and a water repellent binder is formed, the above electrode catalyst is used as the electrode catalyst.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a fuel cell electrode catalyst, a method for producing the same, and an electrode and a fuel cell using the catalyst.

[0002]

A fuel cell is an electrochemical device that supplies a fuel such as hydrogen or hydrocarbons and an oxidant such as oxygen, and directly converts the chemical energy of the redox reaction into electric energy (electric power). It is a device. Generally, fuel electrode (anode), oxidant electrode (cathode), electrolyte between both electrodes,
And means for supplying fuel gas and oxidant gas to the anode and cathode, respectively.

In such a fuel cell, an electrode catalyst is used for the anode and the cathode. During operation of the fuel cell, the fuel supplied to the anode is oxidized on the electrode catalyst in the presence of the electrolyte to release electrons, and the oxidant supplied to the cathode is discharged to the external circuit on the electrode catalyst in the presence of the electrolyte. The electrons are reduced while consuming the electrons supplied from the anode. The current flowing through the external circuit by this series of operations is used as electric power under a constant load.

In the fuel cell, the electrode catalyst as described above plays an important role, and the output and life of the fuel cell largely depend on the characteristics of the electrode catalyst. Therefore, various researches and developments for obtaining an electrocatalyst having higher characteristics have been conventionally carried out for the purpose of realizing a fuel cell having a larger output and a longer life.

As a concrete electrode catalyst, platinum (Pt) and palladium (P
d), rhodium (Rh), ruthenium (Ru), iridium (Ir), osmium (Os), silver (Ag), gold (Au), or a combination of two or more thereof is metallic black. Was used in the form of.

Further, alloy catalysts of these noble metals with one or more base metals such as aluminum, chromium, manganese, iron, cobalt, nickel and copper (US Pat. Nos. 3,428,490 and 3,468,717), etc. Was used. However, since these catalysts use a large amount of noble metal due to their small metal surface area, and because they are extremely easy to sinter in the electrolyte, the catalyst life is short,
It wasn't economical.

[0007] After that, those in which a noble metal component is dispersed and carried on a conductive powder carrier such as carbon black has come to be used. Such a carbon powder-supported catalyst can significantly reduce the amount of the noble metal used as compared with the above-mentioned noble metal catalyst and alloy catalyst with a base metal, and thus contributes greatly to the improvement of the economical efficiency of fuel cell power generation. , Is expected as a promising basic form of electrode catalyst.

By the way, in order for the phosphoric acid fuel cell, which is the closest to practical use at present, to spread widely as a practical power generation system, it is necessary to have an operating life of 40,000 hours or more at an output of a certain level or more. It is said that. In recent years, with the aim of developing a fuel cell having high efficiency, long life, and high economic efficiency, development of a carbon powder-supported catalyst that is highly active mainly for a redox reaction at the cathode has been advanced.

That is, first, a supported binary alloy catalyst of a platinum group metal and a base metal such as vanadium, aluminum, titanium or chromium was found (US Pat. No. 4,186,110).
U.S. Pat. Nos. 4,202,934 and 4,316,944), followed by a supported platinum ternary alloy catalyst obtained by adding cobalt to platinum-vanadium or platinum-chromium for further higher activation (U.S. Pat. No. 4,447,506). Alternatively, platinum-cobalt-nickel supported platinum ternary alloy catalyst (Japanese Patent Laid-Open No. 61-8851) and the like are disclosed. Further, a supported platinum-iron binary ordered alloy (Pt ₃ Fe superlattice alloy) catalyst (Japanese Patent Laid-Open No. 60-7941)
Japanese Patent Application Laid-Open (Kokai) Publication), and a supported platinum-chromium-cobalt ternary ordered alloy catalyst is proposed (US Pat. No. 471).
1829). Further, a platinum-iron-cobalt ternary alloy catalyst having improved catalytic activity and improved retention of metal surface area (JP-A-62-163746).
Is disclosed.

[0010]

However, each of the above-mentioned various conventional carbon powder-supported catalysts has the activity required for the electrode catalyst in order to realize the above-mentioned practical fuel cell. It has not reached the level of life at the same time.

Therefore, the first object of the present invention is to have a high activity and a long life, which can contribute to the realization of a practical fuel cell having a large output and a long life, as compared with the above-mentioned conventional carbon powder-supported catalyst. Another object of the present invention is to provide a fuel cell electrode catalyst. A second object of the present invention is to provide an optimal method for producing such a highly active and long-life fuel cell electrode catalyst. Furthermore, the third object of the present invention is to provide a highly active and long-life electrode using such highly active and long-life electrode catalyst, and a practical fuel cell with large output and long life. That is.

[0012]

[Means for Solving the Problems] [1. Inventions according to claims 1 to 5: fuel cell electrode catalyst]
The invention according to claim 1 is a conductive carbon powder carrier, and P
In a fuel cell electrode catalyst having metal catalyst particles, which are made of a Pt material selected from t and a Pt alloy and are dispersed and carried on the conductive carbon powder carrier, an oxide and a water are provided on the surface of the metal catalyst particles. A compound containing at least one element selected from Nb, Ni, Sn, Ta, Ti, and Zr and a compound selected from oxides and Si is deposited. There is.

In the invention according to claim 1 having the above structure, Nb, Ni, Sn, Ta, Ti and Z
Oxides and hydroxides containing both Si and at least one element selected from r are present at the supporting edge of fine particles of Pt or Pt alloy dispersed and supported on the conductive carbon powder carrier. , Proceeds in a cathode atmosphere in which a high temperature phosphoric acid electrolyte and oxygen as an oxidant coexist,
It has the effect of suppressing elution and sintering of catalytically active metals.

Further, in a high temperature phosphoric acid electrolyte, Zr and Si
Even if reacts with phosphoric acid, zirconium phosphate and silicon phosphate, which are insoluble in phosphoric acid, are generated and stabilized, respectively, so that the suppressing effect does not change for a long time. Furthermore, oxides and hydroxides (both zirconium phosphate and silicon phosphate are included when they are formed) containing both Zr and Si existing in the periphery of supporting fine particles of Pt or Pt alloy are phosphoric acid. Since it has an affinity with the electrolyte, it forms an appropriate wetting site with phosphoric acid and is effective in improving the oxygen reduction reaction.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, the composition of the supported metal of the fuel cell electrode catalyst is set as follows. That is, in the invention of claim 2, the composition of the supported metal is
At least one element selected from Nb, Ni, Sn, Ta, Ti, and Zr and Si are all 10 wt% or more, and the Pt material is 4
0% by weight or more.

According to the invention of claim 2 having the above configuration, the following actions and effects can be obtained. That is, for example, in the composition of Pt (Pt alloy) -Zr, Si-supported metal, when at least one of the two elements of Zr and Si is less than 10% by weight, the effect of adding Zr and Si does not significantly appear. , Pt (Pt alloy) -Zr-based or Pt (Pt alloy) -Si-based catalysts exhibit only the same performance. Further, when Pt (Pt alloy) is less than 40% by weight, the catalytically active metal surface area is insufficient and the catalytic activity is lowered. Therefore, according to the invention of claim 2, Z
Each of the two elements of r and Si is 10% by weight or more,
Moreover, when the Pt material is 40% by weight or more, high catalytic activity can be obtained.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the invention described in (3), the metal catalyst particles are characterized in a dispersed state. That is, in the invention according to claim 3, the metal catalyst particles are dispersed and supported on the conductive carbon powder carrier in a highly dispersed state having a metal surface area of 60 m ² / g or more.

According to the invention of claim 3 having the above-mentioned structure, the following actions and effects can be obtained. That is, when the metal catalyst particles are less than 30 m ² / g, the activity per unit weight is insufficient and it is not economical. Therefore, the metal catalyst particles should be 30 m ² / g or more, preferably,
The activity per unit weight can be increased by being dispersed and supported on the carbon powder carrier in a highly dispersed state having a metal surface area of 60 m ² / g or more according to the invention of claim 3.

The invention according to claim 4 is characterized in that, in the invention according to any one of claims 1 to 3, the deposited amount of the element is. That is, in the invention of claim 4, the deposition amount of at least one element selected from Nb, Ni, Sn, Ta, Ti, and Zr is 1 to 4 weight when calculated as an oxide. According to the invention of the fourth aspect, which has the above-described structure, the following actions and effects can be obtained. That is, the deposition amount of each of the above elements is determined by the oxide (specifically, Nb
₂ O ₃ , NiO, SnO ₂ , Ta ₂ O ₃ , TiO ₂ and ZrO ₂ ), when the amount of deposition of the above elements exceeds 4% by weight, Pt (Pt alloy) on the carrier. The degree of dispersion is reduced, and the improvement in performance is small in proportion to the increase in the applied amount. On the contrary, there is a limit to the degree of dispersion even if the deposited amount is 1% by weight or less. Therefore, by setting the deposition amount of the above element in the range of 1 to 4% by weight according to the invention of claim 4, a sufficient dispersity can be secured and the performance can be improved.

A fifth aspect of the present invention is characterized in that, in the invention according to any one of the first to fourth aspects, the amount of the Pt material carried is set as follows. That is, in the invention according to claim 5, the Pt
The amount of material carried is the same as that of the conductive carbon powder carrier and P
According to the invention of the fifth aspect, which has the above-described structure, the content is 5 to 20% by weight with respect to the total weight of the t material. That is, when the amount of Pt (Pt alloy) supported exceeds 30% by weight, the degree of dispersion of Pt (Pt alloy) on the carrier decreases, and there is little improvement in performance despite the increase in the amount supported, which is an economic advantage. Is reduced. On the contrary, there is a limit to the degree of dispersion even if the loading amount is extremely lowered,
On the contrary, the activity per unit mass of catalyst is lowered, so that a large amount of catalyst is required, which is not preferable. Therefore, Pt
By setting the supported amount of (Pt alloy) to 1 to 30% by weight, preferably 5 to 20% by weight according to the invention of claim 5, with respect to the total weight of the carrier and Pt (Pt alloy).
The performance can be improved by efficiently utilizing Pt (Pt alloy).

[2. Inventions according to claims 6 to 12: Method for producing fuel cell electrode catalyst] The invention according to claim 6 is a method for producing the fuel cell electrode catalyst according to any one of claims 1 to 5. In the above, the following steps of carrying and depositing are sequentially performed. In the loading step, P is deposited on the conductive carbon powder carrier.
A Pt material selected from t and Pt alloys is dispersed and supported to form a supported metal catalyst. In the deposition step, on the surface of the supported metal catalyst formed in the supporting step, a kind selected from oxides and hydroxides and Nb, Ni, Sn, Ta, Ti, and Zr A compound containing both Si and at least one element selected from the above is deposited.

According to a seventh aspect of the present invention, in the method for producing the fuel cell electrode catalyst according to any one of the first to fifth aspects, the following first and second deposition steps are performed. And carrying step are sequentially performed. In the first deposition step, on the conductive carbon powder carrier, a kind selected from oxides and hydroxides and S
A first compound containing i is deposited. In the second deposition step, after the first deposition step, Nb, Ni, Sn, Ta, Ti on the conductive carbon powder carrier are selected from oxides and hydroxides. , And a second compound containing at least one element selected from Zr to form a catalyst carrier. In the loading step, P selected from Pt and Pt alloy is added to the catalyst support formed in the second deposition step.
The t material is dispersed and supported to form a supported metal catalyst.

According to an eighth aspect of the present invention, in the method for producing the fuel cell electrode catalyst according to any one of the first to fifth aspects, the following deposition step and supporting step are sequentially performed. It is characterized by that. That is, in the deposition step, a type selected from oxides and hydroxides and Nb, N are formed on the conductive carbon powder carrier.
A catalyst carrier is formed by depositing a compound containing both Si and at least one element selected from i, Sn, Ta, Ti, and Zr. In the carrying step,
Pt is added to the catalyst carrier formed in the deposition step.
And a Pt material selected from Pt alloys are dispersed and supported to form a supported metal catalyst.

The ninth aspect of the present invention is the method for producing the fuel cell electrode catalyst according to any one of the first to fifth aspects, wherein the three types of supported metals are collectively treated as follows. It is characterized in that it is carried by. That is, in the invention according to claim 9, Nb, Ni, Sn, T
Conducting conductivity using a mixed solution containing at least one element selected from a, Ti, and Zr and Si and a Pt material selected from Pt and Pt alloys. These three types of components are simultaneously supported on a porous carbon powder carrier.

According to the inventions of claims 6 to 9 having the above-mentioned constitutions, it is possible to easily manufacture the fuel cell electrode catalysts of claims 1 to 5. However, still more, in consideration of easiness of operation and controllability of the loading amount of multi-components, a supported metal catalyst is formed in advance, and thereafter, elements such as Zr and Si are simultaneously deposited. The method of the invention described in 6 is the most practical.

The tenth aspect of the invention is the method for producing a fuel cell electrode catalyst according to any one of the sixth to ninth aspects, and particularly has the following feature in the deposition step. That is, in the invention according to claim 10, in the deposition step, the Nb, Ni, Sn, Ta,
As a treating agent for depositing at least one element selected from Ti and Zr, NbCl ₃ , N
An aqueous solution of a chloride selected from iCl ₂ , SnCl ₄ , TaCl ₃ , TiCl ₄ and ZrCl ₂ is used.

According to the invention of the tenth aspect having the above-mentioned constitution, the elements such as Zr can be deposited easily and efficiently by using the aqueous solution of various chlorides. As the treatment agent for depositing Si, for example, Na ₄ SiO ₄ (water glass) or choline silica solution can be used.

The eleventh aspect of the present invention is characterized in that, in the invention according to any one of the sixth to tenth aspects, the method further comprises the step of subjecting the conductive carbon powder carrier to a high temperature heat treatment.

According to the eleventh aspect of the present invention having the above-mentioned structure, the following actions and effects can be obtained. That is, as the conductive carbon powder suitable as the carrier material of the electrode catalyst, for example, conductive carbon black, acetylene black, graphite powder or the like can be used. Specifically, the product name "Vul of Cabot"
can XC-72R "," Vulcan XC-7 "
2 ”or the product name“ Shawi ”of Gulfoil.
and acetylene black marketed as "Nigan Black". Where Vulcan XC
Materials such as -72R are subjected to high temperature heat treatment in an inert gas atmosphere or in a vacuum and partially graphitized to obtain a highly corrosive condition in which a high temperature acidic electrolyte and an oxidizing agent such as oxygen coexist. It is desirable to improve the corrosion resistance of the electrode catalyst carrier as described above. Therefore, according to the invention of claim 11, heat-treating a conductive carbon powder carrier at a high temperature to improve corrosion resistance as an electrode catalyst carrier under highly corrosive conditions such as a phosphoric acid fuel cell. You can Further, the carrier material as described above generally has a BET surface area of 60 to 250 m ² / g.

The invention according to claim 12 is the invention according to any one of claims 6 to 11, wherein after each of the steps, the supported metal catalyst is heated to 800 to 1000 ° C in an inert gas. It is characterized by further comprising a step of performing high temperature heat treatment at a temperature.

According to the twelfth aspect of the invention having the above configuration, the following actions and effects can be obtained. That is, the electrode catalyst is 800 to 1000 in an inert gas.
By heat treatment at a temperature of ° C, the oxide or hydroxide of Si in contact with the conductive carbon powder carrier has an increased affinity with carbon (C) (formation of SiC). as a result,
Stable oxides or hydroxides containing both Si and at least one element selected from Nb, Ni, Sn, Ta, Ti, and Zr depending on the carrying edge of fine particles of Pt or Pt alloy. And further enhances the effect of suppressing elution of catalytically active metals and sintering.

[3. Inventions according to claims 13 to 15: Electrode catalyst and fuel cell] The invention according to claim 13 provides an electrode catalyst layer comprising an electrode catalyst and a water-repellent binder on a conductive and acid-resistant support member. In the formed fuel cell electrode, the electrode catalyst is the fuel cell electrode catalyst according to any one of claims 1 to 5.

The fuel cell electrode of the invention according to claim 13 having the structure as described above is the highly active and long-life fuel cell electrode catalyst according to any one of claims 1 to 5. Since it is used, it has high activity and long life.
It is useful as the cathode of phosphoric acid fuel cells. Also,
The water-repellent binder can bind the catalyst layer to the conductive support member and can provide sufficient gas diffusivity to the reaction gas such as hydrogen and oxygen and the generated gas such as water in the catalyst layer. .

According to a fourteenth aspect of the present invention, there is provided a fuel electrode and an oxidant electrode, and means for supplying a fuel gas and an oxidant gas to the fuel electrode and the oxidant electrode, respectively. In a phosphoric acid fuel cell using an acid, the oxidizer electrode is the fuel cell electrode according to claim 13.

According to a fifteenth aspect of the present invention, there is provided a fuel electrode and an oxidant electrode, and means for supplying a fuel gas and an oxidant gas to the fuel electrode and the oxidant electrode, respectively, and a solid electrode is used as an electrolyte between both electrodes. In a polymer electrolyte fuel cell using a polymer, the oxidizer electrode is the fuel cell electrode according to claim 13.

Claims 14 and 1 having the above-mentioned structure
According to the fifth aspect of the invention, since the highly active and long-life fuel cell electrode according to the thirteenth aspect is used, it is possible to realize a practical fuel cell having a large output and a long life.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION

[1. Production of Fuel Cell Electrode Catalyst] The fuel cell electrode catalyst according to the present invention is produced, for example, as follows. First, a powder of conductive carbon black as a carrier material is brought into contact with an aqueous solution or slurry containing a compound of each metal component forming Pt or a Pt alloy to adsorb or impregnate each metal compound or its ion on the carrier.
Then, while stirring the slurry at a high speed, a suitable immobilizing agent, for example, ammonia, hydrazine, formic acid, a dilute solution of formalin or the like is slowly added dropwise to each metal component as an insoluble compound or partially reduced metal fine particles. It is dispersed and supported on a carrier. The Pt compound is 2
A valent or tetravalent chloroplatinic acid, a chloroplatinic acid salt, etc. can be used. When a Pt alloy is used, chloride, nitric acid compound, sulfuric acid compound or the like of each metal to be used as an alloy component can be used. Next, at least one element selected from Nb, Ni, Sn, Ta, Ti and Zr and Si are deposited on the surface of the electrode catalyst particles in which Pt or Pt alloy is dispersed and carried on the conductive carbon powder carrier. The oxide or hydroxide contained together is deposited.

Pt (Pt alloy) and Z as described above
The catalyst precursor slurry containing each metal compound component of r and Si is filtered and then dried in a nitrogen stream. Next, heat treatment is performed at a temperature of 800 to 1000 ° C. in an inert gas. Pt-Zr-S in the composition range of the catalyst of the present invention
The three-element system of i is SiZ when the heat treatment temperature is 600 ° C or lower.
A compound of rO ₄ is formed, but metallization of Pt hardly occurs. The metallization of Pt requires a high temperature treatment of 750 ° C. or higher, more preferably 800 to 1000 ° C., and the holding time is in the range of 30 minutes to 1 hour. Also, long-time heat treatment at an excessively high temperature of 1000 ° C. or higher should be avoided because it causes the crystallite size of the metal to grow and reduces the metal surface area of the catalyst.

The optimum temperature and holding time for the Pt metallization treatment depend on the particle size and dispersity of each metal component or its compound supported on the catalyst precursor. When the particles are supported with a small particle size and high dispersion, a stable compound of SiZrO ₄ is formed at a lower temperature and in a shorter time with a sufficient metallization, and the Pt catalyst particle size generated is also small and highly dispersed. You can get The preferred particle size of the electrode catalyst of the present invention is 100 A or less, and more preferably 5 A or less.
It is 0 A or less. To obtain such microcrystallites,
The particle size of the supported metal or its compound on the catalyst precursor is 5
It is necessary to control the slurry concentration, the addition rate of the Zr and Si solution, the stirring rate, the reduction metallization treatment condition, etc. in the supporting step so as to be 0 A or less, and more preferably 30 A or less.

[2. Fuel Cell Electrode] The fuel cell electrode of the present invention using the above electrode catalyst will be described below. The fuel cell electrode of the present invention comprises a Pt (Pt alloy) -Zr-Si-based electrode catalyst and a water-repellent binder, for example, a polymer binder such as polytetrafluoroethylene or polyfluoroethylene propylene, which is conductive and acid-resistant. Is an electrode for a fuel cell, which is bound to a water-repellent supporting member, for example, a graphite paper which has been previously subjected to water repellent treatment.

Such a fuel cell electrode is manufactured, for example, as follows. First, a Pt (Pt alloy) -Zr-Si based electrode catalyst is manufactured by the method as described above, and then this catalyst powder is mixed with a polytetrafluoroethylene suspension (for example, TFE-30 manufactured by Du Pont). Mix to make a uniform suspension. On the other hand, a graphite paper that has been previously subjected to a water-repellent treatment with a similar acid-resistant polymer material is prepared, on which a homogeneous mixed suspension of a catalyst and a water-repellent binder is suction-filtered or sprayed, It is manufactured by coating and affixing by a roll coater method or the like, and then firing in an inert gas atmosphere.

Further, the electrode of the present invention, as described above,
In particular, it is useful as a cathode of a phosphoric acid fuel cell, but not only as an electrode for an acidic electrolyte fuel cell,
It can also be used as a general gas diffusion electrode such as a button battery, a gas sensor electrode, and an electrode for electrolysis.

[0043]

EXAMPLES The present invention will be specifically described below with reference to examples.

[1. Production of Electrode Catalyst for Fuel Cell] [Production Example 1 (Example of production method according to claim 6)] "Pt-ZrO ₂ -SiO ₂ (weight ratio 50: 25: 2
5) Electrocatalyst "Heat-treated conductive carbon black (Cabot, Vulcan XC-7) having a specific surface area of 100 m ² / g
81 g of 2R) was slurried with 1500 ml of deionized water containing 4.0 g of glacial acetic acid. 9.0 g of Pt is replaced with H ₂ Pt
Dissolved with amine in 600 ml of aqueous solution as (OH) ₆ . After the platinum solution was added to the carbon slurry while stirring, the slurry temperature was gradually raised to about 95 ° C. while gradually adding 50 g of a 5% formic acid aqueous solution as a reducing agent. Then, after holding at 95 ° C. for 30 minutes, the mixture was allowed to cool to room temperature, filtered, and the filter cake washed with ion-exchanged water was dried at 95 ° C. for 16 hours in a nitrogen stream. This 10 wt% Pt / C catalyst (C1 ... Comparative example)
Had an MSA (electrochemical metal surface area) of 120 m ² / g.

Next, this 10 wt% Pt / C catalyst (C
1) 50 g is ultrasonically dispersed in 1000 ml of ion-exchanged water to form a uniform slurry, and while stirring this slurry,
A choline silica solution (SiO ₂ 10 mg / m ₂ )
l) After adding 75 ml, 100 ml of gelatin solution (0.2%) was added with further stirring, and stirring was continued for about 20 minutes. Subsequently, zircon oxide dichloride (ZrCl ₂ O)
Add 75 ml of solution (10 mg / ml as ZrO ₂ ),
After further stirring for about 20 minutes, a triethanolamine solution (10%) was added until the pH reached 6.5 to 7.5, and then about 2
Stirred for 0 minutes. Then, it was left to stand until carbon black was precipitated, filtered, and then the filter cake washed with ion-exchanged water was dried in a nitrogen stream at 95 ° C. for 10 hours.
Furthermore, in a 4% by volume hydrogen (residual nitrogen) gas flow, 9
After heating and holding at 00 ° C. for 1 hour, the mixture was allowed to cool to room temperature and the carbon-supported Pt—ZrO ₂ —SiO ₂ catalyst (C
2) was obtained.

[0046] Production Example 2 (Example of the production method according to claim 6)] "Pt-X-SiO ( weight ratio 50:25:25) _{electrocatalyst" (X = Nb 2 O 3} , NiO, SnO 2 , Ta ₂ O ₃ , T
iO ₂ ) ZrO ₂ in Production Example 1 was replaced with X described above, and otherwise X was Nb ₂ O ₃ , NiO, SnO ₂ , Ta ₂ O ₃ and TiO in accordance with Production Example 1.
_The carbon-supported Pt-X-SiO2 catalyst of No. ₂ (C3, C4, C5, C6, and C7, respectively) was produced.

[Production Example 3 (Example of production method according to claim 6)] "Pt alloy-ZrO ₂ -SiO ₂ (weight ratio 50:25:
25) Electrode Catalyst "Pt in the above Production Example 1 was replaced with a Pt alloy (Pt: Cr: C
o = 50: 25: 25 (atomic ratio), other than that, according to Production Example 1, carbon-supported Pt alloy-Zr.
O ₂ was prepared -SiO ₂ catalyst (C8).

[Production Example 4 (Example of production method according to claim 6)] "Pt alloy-X-SiO ₂ (weight ratio 50:25:25)
Electrode catalyst "(X = Nb ₂ O ₃ , NiO, SnO ₂ , Ta ₂ O ₃ , T
iO ₂ ) ZrO ₂ in Production Example 3 is replaced with X described above, and otherwise X is Nb ₂ O ₃ , NiO, SnO ₂ , Ta ₂ O ₃ , TiO in accordance with Production Example 3.
₂ is a carbon supported Pt alloy -X-SiO ₂ catalyst (respectively C9, C10, C11, C12, C13 to.) Was prepared.

[Production Example 5 (Example of production method according to claim 6)] "Pt alloy-ZrO ₂ -SiO ₂ (weight ratio 50:25:
25) Electrode catalyst "In the above Production Example 3, the heating conditions in a 4% by volume hydrogen (balance nitrogen) flow were changed to 500 ° C for 1 hour, and otherwise, in accordance with Production Example 3, carbon-supported Pt alloy-Zr.
O ₂ was prepared -SiO ₂ catalyst (C14).

[Production Example 6 (Example of production method according to claim 6)] "Pt alloy-ZrO ₂ -SiO ₂ electrode catalyst" In the Production Example 3, zircon dichloride (ZrCl)
₂ O) solution and choline silica solution were changed in the charged weights, respectively, and other than that, the (Pt alloy: ZrO ₂ : SiO ₂ ) weight ratio was (40: 3) according to Production Example 3.
0:30), (50:30:20), (60: 20: 2)
0) which is a carbon-supported Pt alloy-ZrO ₂ -SiO ₂
A catalyst (designated as C15, C16, and C17, respectively) was produced.

[Production Example 7 (Example of production method according to claim 7)] "Pt-ZrO ₂ -SiO ₂ (weight ratio 50: 25: 2
5) Electrocatalyst "Heat-treated conductive carbon black (Cabot, Vulcan XC-7) having a specific surface area of 100 m ² / g
81 g of 2R) was slurried in 1500 ml of deionized water containing 4.0 g of glacial acetic acid. This is ultrasonically dispersed to form a uniform slurry, and while this slurry is being stirred, a choline silica solution (as SiO ₂ 10 mg / ml) is added to this.
After adding 75 ml, 100 ml of gelatin solution (0.2%) was added with further stirring and stirring was continued for about 20 minutes. After filtration, the filter cake washed with ion-exchanged water was dried at 95 ° C for 16 hours in a nitrogen stream. This Si
50 g of O ₂ / C catalyst was ultrasonically dispersed in 1000 ml of ion-exchanged water to form a uniform slurry, and the zircon dichloride oxide (ZrCl ₂ O) solution (ZrO
As 10 mg / ml) was added. About 20 more
After stirring for a minute, a triethanolamine solution (10%) was added until the pH became 6.5 to 7.5, and the mixture was stirred for about 20 minutes. After that, leave it until the carbon black precipitates,
After filtration, the filter cake washed with ion-exchanged water was dried in a nitrogen stream at 95 ° C for 10 hours. This ZrO ₂ -SiO
_A platinum solution (9.0 g of Pt dissolved in 600 ml of H ₂ Pt (OH) ₆ in 600 ml of an aqueous solution together with an amine) was added thereto while stirring the slurry of ₂ / C catalyst.
After that, while gradually adding 50 g of a 5% formic acid aqueous solution as a reducing agent, the slurry temperature was gradually raised to about 95 ° C., and then the temperature was kept at 95 ° C. for 30 minutes, then allowed to cool to room temperature, and ion-exchanged after filtration. The filter cake washed with water was dried in a nitrogen stream at 95 ° C for 16 hours. Further, after heating and holding at 900 ° C. for 1 hour in a 4% by volume hydrogen (remainder nitrogen) stream, the mixture was allowed to cool to room temperature and carbon-supported Pt-
A ZrO ₂ —SiO ₂ catalyst (C18) was obtained.

[Production Example 8 (Example of production method according to claim 8)] "Pt-ZrO ₂ -SiO ₂ (weight ratio 50: 25: 2
5) Electrocatalyst "Heat-treated conductive carbon black (Cabot, Vulcan XC-7) having a specific surface area of 100 m ² / g
81 g of 2R) was slurried in 1500 ml of deionized water containing 4.0 g of glacial acetic acid. This is ultrasonically dispersed to form a uniform slurry, and while this slurry is being stirred, a choline silica solution (as SiO ₂ 10 mg / ml) is added to this.
After adding 75 ml, 100 ml of gelatin solution (0.2%) was added with further stirring and stirring was continued for about 20 minutes. Subsequently, 75 ml of zircon oxide dichloride (ZrCl ₂ O) solution (10 mg / ml as ZrO) was added, and the mixture was further stirred for about 20 minutes, and then triethanolamine solution (1
0%) until pH 6.5-7.5 is added, and the mixture is stirred for about 20 minutes, then allowed to stand until carbon black precipitates, filtered, and washed with ion-exchanged water. It was dried at 0 ° C. for 10 hours. While stirring the slurry of the ZrO ₂ —SiO ₂ / C catalyst, a platinum solution (Pt 9.0 g as H ₂ Pt (OH) ₆ dissolved in 600 ml of an aqueous solution together with an amine) was added thereto. Then, while gradually adding 50 g of a 5% formic acid aqueous solution as a reducing agent, the slurry temperature was adjusted to about 95 ° C.
After that, the temperature of the filter cake was maintained at 95 ° C. for 30 minutes, allowed to cool to room temperature, filtered, and washed with ion-exchanged water. The filter cake was dried at 95 ° C. for 16 hours in a nitrogen stream. Further, the mixture was heated and held at 900 ° C. for 1 hour in a 4% by volume hydrogen (remainder nitrogen) stream, and then allowed to cool to room temperature to obtain a carbon-supported Pt—ZrO ₂ —SiO ₂ catalyst (C19).

Production Example 9 (Comparative Example) "Pt Alloy-ZrO ₂ -SiO ₂ Electrocatalyst" Zirconium dichloride oxide (ZrCl) in Production Example 3 above.
₂ O) solution and choline silica solution were changed in the charged weights, respectively, except that the weight ratio of (Pt alloy: ZrO ₂ : SiO ₂ ) was (70: 2) according to Production Example 3.
3: 7), (70: 8: 22), (85: 7: 8),
(34:33:33) carbon-supported Pt alloy-Z
rO ₂ —SiO ₂ catalyst (C20, C21, C2, respectively)
2 and C23. ) Manufactured.

[Production Example 10 (Comparative Example)] "Pt alloy-ZrO ₂ (weight ratio 70:30) electrode catalyst" In Production Example 1, the carbon-supported Pt catalyst (C1).
Zirconium oxide dichloride (ZrCl ₂ O) solution (ZrO ₂
As the catalyst, a carbon-supported Pt alloy-ZrO ₂ (weight ratio 70:30) catalyst (C24) was produced according to Production Example 1 except that only 75 mg of 10 mg / ml) was used to support ZrO ₂ .

[Production Example 11 (Comparative Example)] "Pt alloy-SiO ₂ (weight ratio 70:30) electrode catalyst" In Production Example 1, carbon-supported Pt catalyst (C1).
Choline silica solution (as SiO ₂ 10 mg / ml) 7
Only 5 ml was used to support only SiO ₂ , and otherwise, according to Production Example 1, carbon-supported Pt alloy-Si.
O ₂ (weight ratio 70:30) catalyst (C25) was produced.

[Production Example 12 (Comparative Example)] "Pt-Cr-Co (atomic ratio 50:25:25) alloy catalyst" In Production Example 1, the carbon-supported Pt catalyst (C1).
On the other hand, 0.67 g is chromium nitrate and Co0.7
Using a mixed aqueous solution containing 6 g as cobalt nitrate,
Pt—Cr—Co alloy catalyst supporting carbon (C26) according to Production Example 1 except that Cr and Co are supported.
Was manufactured.

[Explanation of Evaluation Contents] In the specification of the present application, the activity of the oxygen reduction reaction is determined by the maximum current density (mA / mA / nm) shown by the oxygen electrode half cell at the hydrogen reference electrode (RHE, the same applies below) plus 900 mv. cm ² electrode area), the current density per unit mass of platinum is called mass activity (mA / mgPt), and this is divided by the metal surface area per unit mass of platinum (m ² / gPt) to obtain the specific activity. (ΜA / cm ² Pt). The metal surface area is determined by measuring the amount of electricity in the process of hydrogen adsorption on the metal surface in the cathodic sweep of cyclic voltammetry, which is EC. MSA (m ² / gP
It is represented by t). Furthermore, the stability of the electrocatalyst is determined by measuring the EC. It is represented by the retention rate of MSA (m ² / gPt).

[2. Production of Fuel Cell Electrodes] The catalysts C1 to C26 obtained in Production Examples 1 to 12 above were each used as an aqueous dispersion of polytetrafluoroethylene (Dup).
sonication, TFE-30). By adding aluminum trichloride to this mixed slurry, flocculent lump was coagulated and precipitated. A cotton-like lump containing each catalyst (C1 to C26) and polytetrafluoroethylene in a dry weight ratio of 50:50 was deposited on a graphite paper support material that had been previously treated to be water repellent, and after pressing and drying, a nitrogen stream was provided. It is baked at 350 ° C for 15 minutes and the electrode (E1
~ E26) was prepared. These electrodes are all 1 cm
It was prepared to contain 0.50 mg of supported metal per ² parts.

[3. Electrode Performance Test] The electrodes according to the examples and comparative examples manufactured as described above were subjected to the following performance tests, and the results shown in Tables 1 and 2 were obtained.

[3-1. Specific Activity Test for Oxygen Reduction Reaction] 105% phosphoric acid was used as an electrolyte, and the oxygen electrode half-cell characteristics of each electrode were measured while passing oxygen gas at a flow rate of 500 ml / cm ² at 200 ° C. to an electrode test piece of 20 mmφ Then, the specific activity (μA / cm ² Pt) was determined from the data, and the results shown in Tables 1 and 2 were obtained. As is clear from these tables, the electrodes E2 to E19 (excluding E14) using the carbon-supported electrocatalyst that is an example of the present invention
Is more than 4 times as active as the electrode (E1) using a single Pt-supported electrocatalyst, and is conventionally known as Pt-Cr.
It was highly active as compared with the -Co alloy catalyst (E26).

Carbon-supported Pt-ZrO ₂ -S of the present invention
Even with the iO ₂ catalyst system, the specific activity was small when the Pt composition was as low as less than 40% by weight (E23) or when only ZrO ₂ or SiO ₂ was supported (E24, E25).

[3-2. Electrode stability test] For each electrode, use an aging cell and add +75 in 105% phosphoric acid.
20 while applying a constant potential of 0 mV (vs. RHE)
After holding at 0 ° C. for 100 hours, the EC. MSA is measured and EC. When compared with MSA, the results shown in Tables 1 and 2 were obtained. As is clear from these tables, the electrodes E2 to E19 (excluding E14) based on the carbon-supported electrocatalyst, which are the examples of the present invention, are the single P
The stability was about twice that of the electrode (E1) using the t-supported electrocatalyst. In addition, the conventionally known Pt-Cr-
Even the Co alloy catalyst (E26) was less than 70%.

Carbon-supported Pt-ZrO ₂ -S of the present invention
Even with an iO ₂ -based catalyst, when the Pt composition is as low as less than 40% by weight (E23) or conversely exceeds 60% by weight (E20, E21, E22), or only ZrO ₂ or SiO ₂ is used. When loaded (E24, E25)
Has a retention rate of 70% or less, which is relatively low.

[0064]

[Table 1]

[Table 2]

[0065]

As is apparent from the above description, according to the present invention, it is possible to contribute to the realization of a practical fuel cell having a large output and a long life, as compared with the conventional carbon powder-supported catalyst. It is possible to provide a long-life fuel cell electrode catalyst. Carbon supported Pt-ZrO ₂ -Si the present invention
The O ₂ -based electrode catalyst exhibits a performance far superior to that of the conventional electrode catalyst in terms of both initial activity and life as a cathode catalyst for fuel cells. The acidic electrolyte fuel cell configured by using the electrode of the present invention including such an electrode catalyst has excellent output performance, a long operating life, and a large economic effect.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01M 4/88 H01M 4/96 M 4/96 B01J 23/64 102M

Claims (15)

[Claims] 1. A conductive carbon powder carrier, Pt and Pt
An electrode catalyst for a fuel cell, comprising a supported metal catalyst particle, which is made of a Pt material selected from an alloy and dispersed and supported on the conductive carbon powder carrier, comprising: an oxide and a hydroxide on the surface of the supported metal catalyst particle. Nb, Ni, Sn, Ta, T of the kind selected from the objects
A fuel cell electrode catalyst, wherein a compound containing both Si and at least one element selected from i and Zr is deposited. 2. The composition of the metal supported on the fuel cell electrode catalyst is Nb, Ni, Sn, Ta, Ti, and Zr.
2. The fuel cell according to claim 1, wherein the content of at least one element selected from the above and Si is 10 wt% or more, and the Pt material is 40 wt% or more. Electrode catalyst. 3. The metal catalyst particles are dispersed and carried on the conductive carbon powder carrier in a highly dispersed state having a metal surface area of 60 m ² / g or more. The fuel cell electrode catalyst described. 4. The deposition amount of at least one element selected from Nb, Ni, Sn, Ta, Ti, and Zr is in the range of 1 to 4% by weight when calculated as an oxide. The fuel cell electrode catalyst according to any one of claims 1 to 3, wherein 5. The loading amount of the Pt material is 5 to 2 with respect to the total weight of the conductive carbon powder carrier and the Pt material.
It is 0 weight%, It is characterized by the above-mentioned.
The electrode catalyst for a fuel cell according to any one of 1. 6. The method for producing an electrode catalyst for a fuel cell according to claim 1, wherein the Pt material selected from Pt and a Pt alloy on a conductive carbon powder carrier. A supporting step of forming and supporting a dispersed metal to form a supported metal catalyst; and a type selected from oxides and hydroxides on the surface of the supported metal catalyst formed in the supporting step.
Manufacture of a fuel cell electrode catalyst comprising a deposition step of depositing a compound containing both Si and at least one element selected from b, Ni, Sn, Ta, Ti, and Zr. Method. 7. The method for producing a fuel cell electrode catalyst according to claim 1, wherein the conductive carbon powder carrier is selected from oxides and hydroxides. Selected from oxides and hydroxides on the conductive carbon powder carrier after the first deposition step of depositing a first compound of a different type and containing Si, and after the first deposition step. A second deposition step of forming a catalyst carrier by depositing a second compound of the selected type and containing at least one element selected from Nb, Ni, Sn, Ta, Ti, and Zr. , The catalyst carrier formed in the second deposition step,
A method for producing a fuel cell electrode catalyst, comprising a supporting step of supporting a Pt material selected from Pt and a Pt alloy in a dispersed manner to form a supported metal catalyst. 8. The method for producing a fuel cell electrode catalyst according to claim 1, wherein the conductive carbon powder carrier is selected from oxides and hydroxides. Different types and Nb, Ni, Sn, Ta, T
a deposition step of depositing a compound containing both Si and at least one element selected from i and Zr to form a catalyst support; and the catalyst support formed in the deposition step. , Pt
And a supporting step of supporting a Pt material selected from among Pt alloys in a dispersed manner to form a supported metal catalyst. 9. The method for producing a fuel cell electrode catalyst according to claim 1, wherein at least one selected from Nb, Ni, Sn, Ta, Ti, and Zr. Using a mixed solution containing one element and all three kinds of elements of Si and a Pt material selected from Pt and a Pt alloy, these three kinds of elements are placed on a conductive carbon powder carrier. A method for producing an electrode catalyst for a fuel cell, which comprises simultaneously supporting the same. 10. In the depositing step, as a treating agent for depositing at least one element selected from Nb, Ni, Sn, Ta, Ti, and Zr, NbCl ₃ , NiCl ₂ , SnCl ₄ ,
The method for producing an electrode catalyst for a fuel cell according to claim 6, wherein an aqueous solution of a chloride selected from TaCl ₃ , TiCl ₄ , and ZrCl ₂ is used. . 11. The method for producing an electrode catalyst for a fuel cell according to claim 6, further comprising a step of heat-treating the conductive carbon powder carrier at a high temperature. 12. The method according to claim 6, further comprising a step of subjecting the supported metal catalyst to a high temperature heat treatment in an inert gas at a temperature of 800 to 1000 ° C. after each of the steps. The method for producing an electrode catalyst for a fuel cell according to any one of the above. 13. A fuel cell electrode comprising an electrocatalyst and an acid-resistant support member, on which an electrocatalyst layer comprising an electrocatalyst and a water-repellent binder is formed, wherein the electrocatalyst is the electrocatalyst. An electrode for a fuel cell, comprising the electrode catalyst for a fuel cell according to claim 5. 14. A fuel electrode and an oxidant electrode, and means for supplying a fuel gas and an oxidant gas to the fuel electrode and the oxidant electrode, respectively, and using phosphoric acid as an electrolyte between both electrodes. The phosphoric acid fuel cell, wherein the oxidant electrode is the fuel cell electrode according to claim 13. 15. A fuel electrode and an oxidant electrode, and means for supplying a fuel gas and an oxidant gas to the fuel electrode and the oxidant electrode, respectively, and using a solid polymer as an electrolyte between both electrodes. 14. The solid polymer fuel cell according to claim 13, wherein the oxidant electrode is the fuel cell electrode according to claim 13.