JP5106342B2 - Catalyst, method for producing the same and use thereof - Google Patents

Description

  The present invention relates to a catalyst, a method for producing the same, and uses thereof.

  Fuel cells are classified into various types depending on the type of electrolyte and the type of electrode, and representative types include alkali type, phosphoric acid type, molten carbonate type, solid electrolyte type, and solid polymer type. Among them, a polymer electrolyte fuel cell that can operate at a low temperature (about −40 ° C.) to about 120 ° C. attracts attention, and in recent years, development and practical application as a low-pollution power source for automobiles is progressing. As a use of the polymer electrolyte fuel cell, a vehicle driving source and a stationary power source are being studied. However, in order to be applied to these uses, durability over a long period of time is required.

  In this polymer solid fuel cell, a polymer solid electrolyte is sandwiched between an anode and a cathode, fuel is supplied to the anode, oxygen or air is supplied to the cathode, and oxygen is reduced at the cathode to extract electricity. is there. Hydrogen or methanol is mainly used as the fuel.

  Conventionally, in order to increase the reaction rate of the fuel cell and increase the energy conversion efficiency of the fuel cell, the fuel cell cathode (air electrode) surface or anode (fuel electrode) surface has a layer containing a catalyst (hereinafter referred to as “for fuel cell use”). Also referred to as “catalyst layer”).

  As this catalyst, a noble metal is generally used, and platinum which is stable at a high potential and has a high activity among noble metals has been mainly used. However, since platinum is expensive and has limited resources, the development of an alternative catalyst has been sought.

  In addition, the noble metal used on the cathode surface may be dissolved in an acidic atmosphere, and there is a problem that the noble metal is not suitable for applications that require long-term durability. Therefore, there has been a strong demand for the development of a catalyst that does not corrode in an acidic atmosphere, has excellent durability, and has high oxygen reducing ability.

  In recent years, materials containing non-metals such as carbon, nitrogen, and boron have attracted attention as catalysts instead of platinum. These non-metal-containing materials are cheaper and have abundant resources than precious metals such as platinum.

  Non-Patent Document 1 reports that a ZrOxN compound based on zirconium exhibits oxygen reducing ability.

  Patent Document 1 discloses an oxygen reduction electrode material containing one or more nitrides selected from the group of elements of Group 4, Group 5 and Group 14 of the long periodic table as a platinum substitute material.

  However, these materials containing non-metals have a problem that practically sufficient oxygen reducing ability is not obtained as a catalyst.

  Further, Patent Document 2 discloses a carbonitride oxide obtained by mixing carbide, oxide, and nitride and performing heat treatment at 500 to 1500 ° C. in a vacuum, an inert or non-oxidizing atmosphere.

  However, the oxycarbonitride disclosed in Patent Document 2 is a thin film magnetic head ceramic substrate material, and the use of this oxycarbonitride as a catalyst has not been studied.

Although platinum is useful not only as a catalyst for the fuel cell, but also as an exhaust gas treatment catalyst or an organic synthesis catalyst, platinum is expensive and has limited resources. There has been a demand for the development of a catalyst that can be used in various applications.
S. Doi, A .; Ishihara, S .; Mitsushima, N .; Kamiya, and K.K. Ota, Journal of The Electrochemical Society, 154 (3) B362-B369 (2007) JP 2007-31781 A Japanese Patent Laid-Open No. 2003-342058

  An object of the present invention is to solve such problems in the prior art, and an object of the present invention is to provide a catalyst that does not corrode in an acidic electrolyte or at a high potential, has excellent durability, and has a high oxygen reduction ability. There is.

  As a result of intensive studies to solve the above-described problems of the prior art, the present inventors have found one or more Group 3 transition metal compounds and one or more Group 4 or 5 having a crystallite size in the range of 1 to 100 nm. It is found that the Group 4 or Group 5 metal oxynitride mixture containing a Group transition metal oxide does not corrode in an acidic electrolyte or at a high potential, has excellent durability, and has a high oxygen reducing ability, The present invention has been completed.

The present invention relates to the following (1) to (8) , for example.
(1)
Of the Group 4 or Group 5 transition metal comprising one or more Group 3 transition metal compounds and one or more Group 4 or Group 5 transition metal oxides having a crystallite size in the range of 1 to 100 nm. A carbonitride oxide mixture,
The Group 3 transition metal is at least one selected from the group consisting of yttrium and cerium;
The Group 4 or 5 transition metals are, fuel cell electrode catalyst which is a titanium down.

(2)
Obtaining a metal carbonitride mixture comprising one or more Group 3 transition metal compounds and one or more Group 4 or Group 5 transition metal oxides;
Heat-treating the metal carbonitride mixture in an oxygen-containing gas to obtain a metal carbonitride oxide mixture,
The Group 3 transition metal is at least one selected from the group consisting of yttrium and cerium;
The Group 4 or 5 transition metals The production method of an electrode catalyst for a fuel cell according to (1) that it is a titanium down.
(3)
A fuel cell electrode catalyst layer comprising the catalyst according to (1) .

(4)
The electrode catalyst layer for a fuel cell according to (3) , further comprising electron conductive particles.
(5)
An electrode comprising the fuel cell electrode catalyst layer according to (3) or (4) and a porous support layer.

(6)
A membrane electrode assembly having a cathode, an anode, and an electrolyte membrane disposed between the cathode and the anode, wherein the cathode and / or the anode is an electrode according to (5) Membrane electrode assembly.

(7)
A fuel cell comprising the membrane electrode assembly according to (6) .

(8)
Polymer electrolyte fuel cell comprising the membrane electrode assembly according to (6).

  The catalyst of the present invention does not corrode in an acidic electrolyte or at a high potential, is stable, has a high oxygen reducing ability, and is inexpensive compared with platinum. Therefore, the fuel cell including the catalyst is relatively inexpensive and has excellent performance.

<Catalyst>
The catalyst of the present invention is a metal carbonitride oxide mixture containing one or more Group 3 transition metal compounds and one or more Group 4 or Group 5 transition metal oxides having a crystallite size in the range of 1 to 100 nm. It is characterized by consisting of.

  The ratio and crystallite size of the Group 3 transition metal compound, Group 4 or Group 5 transition metal oxide in the catalyst of the present invention can be determined by Rietveld analysis.

  Conventionally, an analysis method called “Rietveld analysis” is known as an analysis method for specifying a crystal structure of a substance having a plurality of crystal phases. The details will be described below.

  In the Rietveld analysis, first, an approximated calculation is performed so that the measured diffraction pattern of the sample to be analyzed is obtained by the X-ray diffraction method (XRD method), and this measured diffraction pattern matches the calculated diffraction pattern based on the approximate calculation formula. An analysis technique called so-called pattern fitting that refines various parameters included in the equation is used. When various parameters are refined in this way, the ratio of a plurality of crystal phases (for example, monoclinic phase, tetragonal crystal, cubic crystal) and the size crystal of each crystallite are determined from the values of specific parameters. (Diameter) can be calculated.

At this time, in order to obtain a precise analysis parameter, the diffraction angle 2θ to be measured is preferably 10 to 110 °. Similarly, the diffraction angle interval to be measured is preferably 0.02 ° or less. Further, similarly, the measurement time is preferably set so that the diffraction intensity of the maximum peak of the obtained X-ray diffraction pattern is 5000 or more. In order to perform this Rietveld analysis, software for Rietveld analysis such as RIETAN-2000 can be used.
The catalyst of the present invention contains at least one group 3 transition metal compound. The Group 3 transition metal element may be either a lanthanoid or an aquinoid.

  In particular, the element of the group 3 transition metal compound is preferably at least one member selected from the group consisting of scandium, yttrium, lanthanum, cerium, samarium, dysprosium, and holmium.

  Although details are unknown, in general, a Group 3 transition metal element is likely to be dissolved in a Group 4 or Group 5 transition metal oxide. In the group 4 or group 5 transition metal oxide, the group 3 transition metal element becomes a defect, and the particle size is considered to be small in order to suppress crystal growth of the group 4 or group 5 transition metal oxide.

  When the particle size is small, the specific surface area is large, which is preferable as a catalyst. Moreover, it is speculated that the point which becomes a defect acts as an active point and enhances the catalytic activity.

  Although the addition amount of a group 3 transition metal compound changes with metal types, 0.1-20 mol% in all the transition metal compounds in a catalyst is preferable. If the amount of Group 3 transition metal compound added is less than 0.1 mol%, the effect may be reduced. Moreover, when there is more addition amount of a group 3 transition metal compound than 20 mol%, there exists a possibility that the catalytic action of a metal carbonitrous oxide mixture may be reduced, it is unpreferable.

  Group 3 transition metal elements are considered to be partly dissolved in group 4 or group 5 transition metal oxides, but depending on the type of element and the amount added, group 3 transition metal oxidation It may be detected as an object.

  It is preferable that any one of the Group 4 or Group 5 transition metal is a metal carbonitride because it does not corrode in the acidic electrolyte or at a high potential. In particular, any one of titanium, zirconium, tantalum, and niobium is preferable.

The group 4 or group 5 transition metal oxide referred to here is one that has been refined by Rietveld analysis and matched as an approximate value. One crystallite size of the Group 4 or Group 5 transition metal oxide obtained by Rietveld analysis is 1 to 100 nm. Preferably, it is 3-80 nm. More preferably, it is 5-50 nm. If the crystallite size is smaller than 1 nm, it is not preferable because the particles are aggregated and difficult to handle. If the crystallite size is larger than 100 nm, the catalyst area becomes small and high oxygen reduction ability may not be obtained.
The method for producing the catalyst of the present invention is not particularly limited.

  For example, the present invention includes the Group 4 or Group 5 transition metal carbonitride mixture including any one of the Group 3 transition metal compounds and any one of the Group 4 or Group 5 transition metal oxides. And obtaining the metal carbonitride oxide mixture containing the metal oxide having a crystallite size of 1 to 100 nm by heat-treating the metal carbonitride mixture in an oxygen-containing gas. Obtainable.

  The smaller the particle size of the Group 4 or Group 5 transition metal carbonitride mixture containing any one of Group 3 transition metal compounds and any one of Group 4 or Group 5 transition metal oxides, It is presumed that the crystallite size of the metal oxide in the metal carbonitride obtained by heat-treating the transition metal carbonitride in an oxygen-containing inert gas is reduced.

(Step of obtaining metal carbonitride)
As a step of obtaining any one of the Group 3 transition metal compounds and obtaining the Group 4 or Group 5 transition metal carbonitride mixture containing any one of the Group 4 or Group 5 transition metal oxides,
(I) Heat treatment is performed in a nitrogen atmosphere or the like using as a raw material a group 3, group 4, group 5 transition metal, hydride, oxide, carbide, or nitride appropriately added with carbon that has the metal composition of the present invention. A solid phase method for obtaining a metal carbonitride mixture containing any one of Group 3 transition metals and any one of Group 4 or Group 5 transition metals.

(II) Metal charcoal containing any one of Group 3 transition metals having a small particle size by combining with a liquid phase method using a complex as a raw material, and containing any one of Group 4 or Group 5 transition metals Method to obtain nitride.
Etc.

  Next, from the manufacturing method of (I), any one of group 3 transition metal compounds using metal oxide and carbon as a raw material is included, and any one of group 4 or group 5 transition metal oxides A method for producing the Group 4 or Group 5 transition metal carbonitride mixture containing the above will be described in detail.

There are no particular restrictions on the Group 4 or Group 5 transition metal oxide. For example, ZrO, ZrO ₂ , Zr ₂ O _5, ZrO, ZrO, ZrO ₂ , Zr ₂ O _5, TiO, Ti ₃ O ₄ , TiO _2, Ti ₃ O ₅ , Ti _N O _2N-1, etc. Titanium oxide is used. Of these, ZrO ₂ and TiO _{2 which} are inexpensive and easily available are preferable.

There are no particular restrictions on the Group 3 transition metal oxide. For _example, such _{Sc 2 O 3, Y 2 O} 3, La 2 O 3, CeO 2, Sm 2 O 3, Dy 2 O 3, Ho 2 O 3 and the like.

Examples of the raw material carbon include carbon, carbon black, graphite, graphite, activated carbon, carbon nanotube, carbon nanofiber, carbon nanohorn, and fullerene. It is preferable that the particle size of the carbon powder is smaller because the specific surface area is increased and the reaction with the oxide is facilitated. For example, carbon black (specific surface area: 100 to 300 m ² / g, for example, XC-72 manufactured by Cabot) is preferably used.

  The compounding amount (molar ratio) is usually 0.1 to 20 mol% of the group 3 transition metal oxide with respect to the group 4 or group 5 transition metal oxide. Moreover, carbon is 1-4 mol with respect to the sum total of the group 4 or group 5 transition metal oxide and the group 3 transition metal oxide. Preferably, the carbon is 2-3 moles.

  These group 3 transition metal oxides, group 4 or group 5 transition metal oxides, and carbon are sufficiently mixed and then heat-treated in a nitrogen atmosphere.

Generally, the heat treatment is performed using an electric furnace. The temperature of heat processing is the range of 1200 to 2200 degreeC, Preferably it is the range of 1400-1700 degreeC. When the heat treatment temperature is less than 1200 ° C., a metal carbonitride mixture containing any one of Group 4 or Group 5 transition metals cannot be obtained. The lower the firing temperature, the smaller the particle size of the metal carbonitride mixture containing any one of Group 4 or Group 5 transition metals, but the raw materials and the like are likely to remain. If the temperature is 2200 ° C. or higher, sintering will increase the particle size, and a metal carbonitride mixture containing a Group 4 or Group 5 transition metal oxide having a crystallite size of 1 to 100 nm of the present invention cannot be obtained. Although depending on the metal species, a metal carbonitride containing any one of Group 4 or Group 5 transition metals having a small particle size with little residual material can be obtained in the range of 1400 to 1700 ° C.

(Process to obtain metal carbonitride)
Next, the process of obtaining a metal carbonitride oxide mixture by heat-treating the metal carbonitride mixture obtained by the above production method in a gas containing oxygen will be described.

  By diluting oxygen with an inert gas, the oxidation can be controlled to proceed uniformly. Examples of the inert gas include nitrogen, helium gas, neon gas, argon gas, krypton gas, xenon gas, and radon gas. Nitrogen or argon gas is particularly preferred because it is relatively easy to obtain.

  Further, hydrogen may be mixed in the inert gas. The hydrogen concentration is preferably 0.0001 to 10% by volume, particularly preferably 0.05 to 5% by volume. Hydrogen is preferable in that the hydrogen concentration is within the above range, a uniform carbonitride oxide is formed. If the hydrogen concentration is less than 0.0001% by volume, the effect of mixing hydrogen is small, which is not preferable. On the other hand, if it exceeds 10% by volume, there is a possibility that sufficient oxidation cannot be carried out.

  The oxygen concentration in this step depends on the heat treatment time and the heat treatment temperature, but is preferably 0.0001 to 10% by volume, particularly preferably 0.03 to 3% by volume. When the oxygen concentration is within this range, it is preferable in that a uniform metal oxynitride mixture is formed.

  Further, if the oxygen concentration is less than 0.0001% by volume, it tends to be in an unoxidized state, and if it exceeds 10% by volume, oxidation tends to proceed excessively.

  The temperature of the heat treatment in this step is usually in the range of 400 to 1400 ° C, preferably in the range of 600 to 1200 ° C. The heat treatment temperature within the above range is preferable in that a uniform metal oxycarbonitride mixture is formed. When the heat treatment temperature is less than 400 ° C., oxidation does not proceed. If it is 1400 ° C. or higher, the progress of oxidation is fast, and there is a possibility that it cannot be controlled.

  Examples of the heat treatment method in this step include a leveling method, a stirring method, a dropping method, a powder trapping method, and the like.

  In the dropping method, an inert gas containing a small amount of oxygen flows through an induction furnace, the furnace is heated to a predetermined heat treatment temperature, and after maintaining a thermal equilibrium at the temperature, the furnace is heated in a crucible that is a heating area of the furnace. In this method, the metal carbonitride mixture as a raw material is dropped and heat-treated. The dropping method is preferable in that the aggregation and growth of the particles of the metal carbonitride oxide mixture can be minimized.

  The powder trapping method means that the metal carbonitride mixture is suspended in a vertical tube furnace maintained at a predetermined heat treatment temperature by splashing and floating the metal carbonitride mixture in an inert gas atmosphere containing a small amount of oxygen. It is a method of capturing and heat-treating.

  As the catalyst of the present invention, the metal oxycarbonitride obtained by the above-described production method and the like may be used as it is, but the resulting metal oxycarbonitride mixture is further pulverized into a finer powder. May be used.

Examples of the method for crushing the metal carbonitride oxide include a roll rolling mill, a ball mill, a medium agitation mill, an airflow crusher, a mortar, a method using a tank disintegrator, and the like. The method using an airflow pulverizer is preferable, and the method using a mortar is preferable from the viewpoint that a small amount of processing is easy.
<Application>
The catalyst of the present invention can be used as an alternative catalyst for a platinum catalyst.

  For example, it can be used as a catalyst for fuel cells, a catalyst for exhaust gas treatment, or a catalyst for organic synthesis.

  The fuel cell catalyst layer of the present invention is characterized by containing the catalyst.

  The catalyst layer for a fuel cell of the present invention can be used for either an anode catalyst layer or a cathode catalyst layer. The catalyst layer for a fuel cell of the present invention includes a catalyst layer (catalyst catalyst for cathode) provided on the cathode of a fuel cell because it contains a catalyst having high oxygen reducing ability and hardly corroded even in a high potential in an acidic electrolyte. Layer). In particular, it is suitably used for a catalyst layer provided on the cathode of a membrane electrode assembly provided in a polymer electrolyte fuel cell.

  The catalyst layer for a fuel cell of the present invention preferably further contains an electron conductive powder. When the fuel cell catalyst layer containing the catalyst further contains an electron conductive powder, the reduction current can be further increased. The electron conductive powder is considered to increase the reduction current because it causes an electrical contact for inducing an electrochemical reaction in the catalyst.

  The electron conductive particles are usually used as a catalyst carrier.

  Examples of the electron conductive particles include carbon, conductive polymers, conductive ceramics, metals, and conductive inorganic oxides such as tungsten oxide or iridium oxide, and these can be used alone or in combination. In particular, since carbon has a large specific surface area, carbon alone or a mixture of carbon and other electron conductive particles is preferable. That is, the fuel cell catalyst layer preferably contains the catalyst and carbon.

  As carbon, carbon black, graphite, graphite, activated carbon, carbon nanotube, carbon nanofiber, carbon nanohorn, fullerene and the like can be used. If the particle size of the carbon is too small, it becomes difficult to form an electron conduction path, and if it is too large, the gas diffusibility of the catalyst layer for fuel cells tends to decrease or the utilization factor of the catalyst tends to decrease. A range of 1000 nm is preferable, and a range of 10 to 100 nm is more preferable.

  When the electron conductive particles are carbon, the weight ratio of the catalyst to carbon (catalyst: electron conductive particles) is preferably 4: 1 to 1000: 1.

  The conductive polymer is not particularly limited. For example, polyacetylene, poly-p-phenylene, polyaniline, polyalkylaniline, polypyrrole, polythiophene, polyindole, poly-1,5-diaminoanthraquinone, polyaminodiphenyl, poly (o- Phenylenediamine), poly (quinolinium) salts, polypyridine, polyquinoxaline, polyphenylquinoxaline and the like. Among these, polypyrrole, polyaniline, and polythiophene are preferable, and polypyrrole is more preferable.

  The polymer electrolyte is not particularly limited as long as it is generally used in a fuel cell catalyst layer. Specifically, a perfluorocarbon polymer having a sulfonic acid group (for example, Nafion (DuPont 5% Nafion solution (DE521), etc.), a hydrocarbon polymer compound having a sulfonic acid group, and an inorganic acid such as phosphoric acid are used. Examples thereof include doped polymer compounds, organic / inorganic hybrid polymers partially substituted with proton-conductive functional groups, and proton conductors in which a polymer matrix is impregnated with a phosphoric acid solution or a sulfuric acid solution. Among them, Nafion (DuPont 5% Nafion solution (DE521)) is preferable.

  Examples of the method for dispersing the catalyst on the electron conductive particles as a support include air flow dispersion and dispersion in liquid. Dispersion in liquid is preferable because a catalyst and electron conductive particles dispersed in a solvent can be used in the fuel cell catalyst layer forming step. Examples of the dispersion in the liquid include a method using an orifice contraction flow, a method using a rotating shear flow, and a method using an ultrasonic wave. The solvent used for dispersion in the liquid is not particularly limited as long as it does not erode the catalyst or electron conductive particles and can be dispersed, but a volatile liquid organic solvent or water is generally used. The

  Further, when the catalyst is dispersed on the electron conductive particles, the electrolyte and the dispersing agent may be further dispersed at the same time.

  The method for forming the catalyst layer for the fuel cell is not particularly limited. For example, a method of applying a suspension containing the catalyst, the electron conductive particles, and the electrolyte to the electrolyte membrane or the gas diffusion layer to be described later. It is done. Examples of the application method include a dipping method, a screen printing method, a roll coating method, and a spray method. In addition, after forming a catalyst layer for a fuel cell on a base material by a coating method or a filtration method using a suspension containing the catalyst, electron conductive particles, and an electrolyte, the catalyst layer for a fuel cell is formed on the electrolyte membrane by a transfer method. The method of forming is mentioned.

  The electrode of the present invention is characterized by having the fuel cell catalyst layer and a porous support layer.

  The electrode of the present invention can be used as either a cathode or an anode. Since the electrode of the present invention is excellent in durability and has a large catalytic ability, it is more effective when used for a cathode.

  The porous support layer is a layer that diffuses gas (hereinafter also referred to as “gas diffusion layer”). The gas diffusion layer may be anything as long as it has electron conductivity, high gas diffusibility, and high corrosion resistance. Generally, carbon-based porous materials such as carbon paper and carbon cloth are used. Materials and aluminum foil coated with stainless steel and corrosion-resistant materials for weight reduction are used.

  The membrane electrode assembly of the present invention is a membrane electrode assembly having a cathode, an anode, and an electrolyte membrane disposed between the cathode and the anode, wherein the cathode and / or the anode is the electrode. It is characterized by that.

  As the electrolyte membrane, for example, an electrolyte membrane using a perfluorosulfonic acid system or a hydrocarbon electrolyte membrane is generally used. However, a membrane or porous body in which a polymer microporous membrane is impregnated with a liquid electrolyte is used. A membrane filled with a polymer electrolyte may be used.

  The fuel cell according to the present invention includes the membrane electrode assembly.

  Fuel cell electrode reactions occur at the so-called three-phase interface (electrolyte-electrode catalyst-reaction gas). Fuel cells are classified into several types depending on the electrolyte used, etc., and include molten carbonate type (MCFC), phosphoric acid type (PAFC), solid oxide type (SOFC), and solid polymer type (PEFC). . Especially, it is preferable to use the membrane electrode assembly of this invention for a polymer electrolyte fuel cell.

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.
[Example 1]
1. Preparation of catalyst 0.17 g (1 mmol) of cerium dioxide, 7.92 g (99 mmol) of titanium oxide, and 3 g (250 mmol) of carbon black (manufactured by Cabot, Vulcan 72) were sufficiently mixed by a ball mill. The mixture was heat-treated at 1500 ° C. for 3 hours in a nitrogen atmosphere. The obtained product was sufficiently pulverized with a ball mill to obtain 7.2 g of a carbonitride mixture.
300 mg of the obtained titanium carbonitride mixture was heat-treated in a tube furnace at 1000 ° C. for 3 hours in a nitrogen atmosphere containing 1.5 vol% oxygen gas and 4 vol% hydrogen. The obtained titanium carbonitride oxide mixture (hereinafter also referred to as “catalyst (1)”) was sufficiently pulverized to obtain 270 mg.
X-ray diffraction spectra were measured using X'Pert PRO MPD. The voltage was 45 V, the current was 40 mA, the diffraction angle 2θ to be measured was 10 to 110 °, and the diffraction angle interval to be measured was 0.016711 °.

  The powder X-ray diffraction spectrum of the catalyst (1) is shown in FIG.

The crystallite size of titanium oxide in the titanium carbonitride oxide mixture was determined from the measured diffraction pattern using Rietveld analysis software JADE manufactured by Rigaku Corporation. The obtained results are shown in Table 1.

２．燃料電池用電極の製造
酸素還元能の測定は、次のように行った。触媒（１）０．０９５ｇとカーボンブラック（キャボット社製 ＸＣ−７２）０．００５ｇをイソプロピルアルコール：純水＝２：１の重量比で混合した溶液１０ｇに入れ、超音波で撹拌、縣濁して混合した。この混合物３０μｌをグラッシーカーボン電極（東海カーボン社製、径：５．２ｍｍ）に塗布し、１２０℃で１時間乾燥した。さらに、ナフィオン（デゥポン社 ５％ナフィオン溶液（ＤＥ５２１））を１０倍に純水で希釈したもの１０μｌを塗布し、１２０℃で１時間乾燥し、燃料電池用電極（１）を得た。

2. Production of Fuel Cell Electrode The oxygen reducing ability was measured as follows. Catalyst (1) 0.095 g and carbon black (Cabot XC-72, 0.005 g) were added to 10 g of a mixture of isopropyl alcohol: pure water = 2: 1 in a weight ratio, stirred with ultrasonic waves and suspended. Mixed. 30 μl of this mixture was applied to a glassy carbon electrode (manufactured by Tokai Carbon Co., Ltd., diameter: 5.2 mm) and dried at 120 ° C. for 1 hour. Further, 10 μl of Nafion (DuPont 5% Nafion solution (DE521)) diluted 10 times with pure water was applied and dried at 120 ° C. for 1 hour to obtain a fuel cell electrode (1).

3. Evaluation of oxygen reducing ability The catalytic ability (oxygen reducing ability) of the thus produced fuel cell electrode (1) was evaluated by the following method.

First, the produced fuel cell electrode (1) was polarized in an oxygen atmosphere and a nitrogen atmosphere in a 0.5 mol / dm ³ sulfuric acid solution at 30 ° C. and a potential scanning speed of 5 mV / sec, and a current-potential curve was obtained. It was measured. At that time, a reversible hydrogen electrode in a sulfuric acid solution having the same concentration was used as a reference electrode.

From the measurement results, the difference between the reduction current in the oxygen atmosphere and the reduction current in the nitrogen atmosphere was determined.
FIG. 2 shows an oxygen reduction current-oxygen reduction potential curve (hereinafter referred to as “current-potential curve”) obtained by the above measurement.
Table 2 shows current values at 0.7 V (vs. NHE). The larger the oxygen reduction current, the higher the catalytic ability (oxygen reducing ability) of the fuel cell electrode (1).

［実施例２］
１．触媒の調製
三酸化二イットリウム０．８１ｇ（２．５ｍｍｏｌ）、酸化チタン７．６ｇ（９５ｍｍｏｌ）、カーボンブラック（キャボット社製、Ｖｕｌｃａｎ７２）３ｇ（２５０ｍｍｏｌ）をボールミルで十分に混合した。該混合物を１５００℃で３時間、窒素雰囲気中で熱処理した。得られた物をボールミルで十分に粉砕し、炭窒化物混合物７．４ｇを得た。
得られたチタンの炭窒化物混合物３００ｍｇを、管状炉で、１０００℃３時間、１．５容量％酸素ガスと４容量％水素を含有する窒素雰囲気中で熱処理した。得られたチタンの炭窒酸化物混合物（以下「触媒（２）」とも記す。）を十分に粉砕し、２７５ｍｇを得た。

[Example 2]
1. Catalyst Preparation 0.81 g (2.5 mmol) of yttrium trioxide, 7.6 g (95 mmol) of titanium oxide, and 3 g (250 mmol) of carbon black (manufactured by Cabot, Vulcan 72) were sufficiently mixed by a ball mill. The mixture was heat-treated at 1500 ° C. for 3 hours in a nitrogen atmosphere. The obtained product was sufficiently pulverized with a ball mill to obtain 7.4 g of a carbonitride mixture.
300 mg of the obtained titanium carbonitride mixture was heat-treated in a tube furnace at 1000 ° C. for 3 hours in a nitrogen atmosphere containing 1.5 vol% oxygen gas and 4 vol% hydrogen. The obtained titanium carbonitride oxide mixture (hereinafter also referred to as “catalyst (2)”) was sufficiently pulverized to obtain 275 mg.

  The X-ray diffraction spectrum was measured in the same manner as in Example 1. The powder X-ray diffraction spectrum of the catalyst (2) is shown in FIG.

  Rietveld analysis was performed in the same manner as in Example 1 to determine the crystallite size of titanium oxide in the titanium carbonitride oxide mixture. The obtained results are shown in Table 1.

2. Production of Fuel Cell Electrode A fuel cell electrode (2) was obtained in the same manner as in Example 1 except that the catalyst (2) was used.

3. Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (2) was used.

  FIG. 4 shows a current-potential curve obtained by the measurement.

Table 2 shows current values at 0.7 V (vs. NHE).
[Example 3]
1. Preparation of catalyst 0.09 g (0.5 mmol) of cerium dioxide, 12.3 g (99.5 mmol) of zirconium oxide, and 3 g (250 mmol) of carbon black (manufactured by Cabot, Vulcan 72) were sufficiently mixed by a ball mill. The mixture was heat-treated at 1700 ° C. for 3 hours in a nitrogen atmosphere. The obtained product was sufficiently pulverized with a ball mill to obtain 11.3 g of a zirconium carbonitride mixture.
300 mg of the obtained zirconium carbonitride mixture was heat-treated in a tube furnace at 1000 ° C. for 3 hours in a nitrogen atmosphere containing 0.75 vol% oxygen gas and 4 vol% hydrogen. The obtained zirconium carbonitride oxide mixture (hereinafter also referred to as “catalyst (3)”) was sufficiently pulverized to obtain 280 mg.
The X-ray diffraction spectrum was measured in the same manner as in Example 1. The powder X-ray diffraction spectrum of the catalyst (3) is shown in FIG.
Rietveld analysis was performed in the same manner as in Example 1, and the monoclinic and tetragonal crystallite sizes of zirconium oxide in the zirconium carbonitride oxide mixture were determined. The obtained results are shown in Table 3.

２．燃料電池用電極の製造
前記触媒（３）を用いた以外は実施例１と同様にして燃料電池用電極（３）を得た。

2. Production of Fuel Cell Electrode A fuel cell electrode (3) was obtained in the same manner as in Example 1 except that the catalyst (3) was used.

3. Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (3) was used.

FIG. 6 shows a current-potential curve obtained by the measurement.
Table 4 shows current values at 0.5 V (vs. NHE).

［実施例４］
１．触媒の調製
三酸化二イットリウム１．６１ｇ（５ｍｍｏｌ）、酸化ジルコニウム７．６ｇ（９０ｍｍｏｌ）、カーボン（キャボット社製、Ｖｕｌｃａｎ７２）３ｇ（２５０ｍｍｏｌ）をボールミルで十分に混合した。該混合物を１７００℃で３時間、窒素雰囲気中で熱処理した。得られた物をボールミルで十分に粉砕し、ジルコニウムの炭窒化物混合物１１．６ｇを得た。
得られたジルコニウムの炭窒化物混合物３００ｍｇを、管状炉で、１０００℃３時間、０．７５容量％酸素ガスと４容量％水素を含有する窒素雰囲気中で熱処理した。得られたジルコニウムの炭窒酸化物混合物（以下「触媒（４）」とも記す。）を十分に粉砕し、２７５ｍｇを得た。

[Example 4]
1. Preparation of catalyst 1.61 g (5 mmol) of yttrium trioxide, 7.6 g (90 mmol) of zirconium oxide, and 3 g (250 mmol) of carbon (manufactured by Cabot, Vulcan 72) were sufficiently mixed by a ball mill. The mixture was heat-treated at 1700 ° C. for 3 hours in a nitrogen atmosphere. The obtained product was sufficiently pulverized with a ball mill to obtain 11.6 g of a carbonitride mixture of zirconium.
300 mg of the obtained zirconium carbonitride mixture was heat-treated in a tube furnace at 1000 ° C. for 3 hours in a nitrogen atmosphere containing 0.75 vol% oxygen gas and 4 vol% hydrogen. The obtained zirconium carbonitride oxide mixture (hereinafter also referred to as “catalyst (4)”) was sufficiently pulverized to obtain 275 mg.

The X-ray diffraction spectrum was measured in the same manner as in Example 1. The powder X-ray diffraction spectrum of the catalyst (4) is shown in FIG.
Rietveld analysis was performed in the same manner as in Example 1, and the monoclinic and tetragonal crystallite sizes of zirconium oxide in the zirconium carbonitride oxide mixture were determined. The obtained results are shown in Table 3.

2. Production of Fuel Cell Electrode A fuel cell electrode (4) was obtained in the same manner as in Example 1 except that the catalyst (4) was used.

3. Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (4) was used.

FIG. 8 shows a current-potential curve obtained by the measurement.
Table 4 shows current values at 0.5 V (vs. NHE).
[Comparative Example 1]
1. Catalyst Preparation 8.0 g (100 mmol) of titanium oxide and 3 g (250 mmol) of carbon black (manufactured by Cabot, Vulcan 72) were mixed thoroughly with a ball mill. The mixture was heat-treated at 1500 ° C. for 3 hours in a nitrogen atmosphere. The obtained product was sufficiently pulverized with a ball mill to obtain 7.2 g of a titanium carbonitride mixture.
300 mg of the obtained titanium carbonitride mixture was heat-treated in a tube furnace at 1000 ° C. for 3 hours in a nitrogen atmosphere containing 1.5 vol% oxygen gas and 4 vol% hydrogen. The obtained titanium carbonitride oxide mixture (hereinafter also referred to as “catalyst (5)”) was sufficiently pulverized to obtain 275 mg.
The X-ray diffraction spectrum was measured in the same manner as in Example 1. The powder X-ray diffraction spectrum of the catalyst (5) is shown in FIG.
Rietveld analysis was performed in the same manner as in Example 1 to determine the crystallite size of titanium oxide in the titanium carbonitride oxide mixture. The obtained results are shown in Table 1.

2. Production of Fuel Cell Electrode A fuel cell electrode (5) was obtained in the same manner as in Example 1 except that the catalyst (5) was used.

3. Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (5) was used.

  FIG. 10 shows a current-potential curve obtained by the measurement.

Table 2 shows current values at 0.7 V (vs. NHE).
[Comparative Example 2]
1. Preparation of Catalyst Zirconium oxide (12.3 g, 100 mmol) and carbon black (manufactured by Cabot, Vulcan 72) (3 g, 250 mmol) were sufficiently mixed by a ball mill. The mixture was heat-treated at 1500 ° C. for 3 hours in a nitrogen atmosphere. The obtained product was sufficiently pulverized by a ball mill to obtain 11.9 g of a zirconium carbonitride mixture.
300 mg of the obtained zirconium carbonitride mixture was heat-treated in a tube furnace at 1000 ° C. for 3 hours in a nitrogen atmosphere containing 0.75 vol% oxygen gas and 4 vol% hydrogen. The obtained zirconium carbonitride oxide mixture (hereinafter also referred to as “catalyst (6)”) was sufficiently pulverized to obtain 275 mg.

  The X-ray diffraction spectrum was measured in the same manner as in Example 1. The powder X-ray diffraction spectrum of the catalyst (6) is shown in FIG.

  Rietveld analysis was performed in the same manner as in Example 1, and the monoclinic and tetragonal crystallite sizes of zirconium oxide in the zirconium carbonitride oxide mixture were determined. The obtained results are shown in Table 3.

2. Production of Fuel Cell Electrode A fuel cell electrode (6) was obtained in the same manner as in Example 1 except that the catalyst (6) was used.

3. Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (5) was used.

FIG. 12 shows a current-potential curve obtained by the measurement.
Table 4 shows current values at 0.5 V (vs. NHE).

The catalyst obtained from the production method of the present invention does not corrode in an acidic electrolyte or at a high potential, has excellent durability, and has a high oxygen reducing ability. Therefore, a catalyst layer for a fuel cell, an electrode, an electrode assembly, or a fuel cell Can be used.

It is a powder X-ray-diffraction spectrum of a catalyst (1). It is an electric current-potential curve of an electrode (1). It is a powder X-ray-diffraction spectrum of a catalyst (2). It is an electric current-potential curve of an electrode (2). It is a powder X-ray-diffraction spectrum of a catalyst (3). It is an electric current-potential curve of an electrode (3). It is a powder X-ray-diffraction spectrum of a catalyst (4). It is an electric current-potential curve of an electrode (4). It is a powder X-ray-diffraction spectrum of a catalyst (5). It is an electric current-potential curve of an electrode (5). It is a powder X-ray diffraction spectrum of a catalyst (6). It is an electric current-potential curve of an electrode (6).

Claims (8)

Of the Group 4 or Group 5 transition metal comprising one or more Group 3 transition metal compounds and one or more Group 4 or Group 5 transition metal oxides having a crystallite size in the range of 1 to 100 nm. A carbonitride oxide mixture,
The Group 3 transition metal is at least one selected from the group consisting of yttrium and cerium;
The Group 4 or 5 transition metals are, fuel cell electrode catalyst which is a titanium down. Obtaining a metal carbonitride mixture comprising one or more Group 3 transition metal compounds and one or more Group 4 or Group 5 transition metal oxides;
Heat-treating the metal carbonitride mixture in an oxygen-containing gas to obtain a metal carbonitride oxide mixture,
The Group 3 transition metal is at least one selected from the group consisting of yttrium and cerium;
The Group 4 or 5 transition metals The production method of an electrode catalyst for a fuel cell according to claim 1, characterized in that the titanium emission. A fuel cell electrode catalyst layer comprising the catalyst according to claim 1 . The electrode catalyst layer for a fuel cell according to claim 3 , further comprising electron conductive particles. 5. An electrode comprising the fuel cell electrode catalyst layer according to claim 3 and a porous support layer. 6. A membrane electrode assembly comprising a cathode, an anode, and an electrolyte membrane disposed between the cathode and the anode, wherein the cathode and / or the anode is an electrode according to claim 5. Membrane electrode assembly. A fuel cell comprising the membrane electrode assembly according to claim 6 . Polymer electrolyte fuel cell comprising the membrane electrode assembly according to claim 6.

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