JP5217434B2 - Fuel cell, its catalyst and its electrode - Google Patents

Description

  The present invention relates to a fuel cell catalyst, a method for producing the same, a fuel cell electrode and a fuel cell using the fuel cell catalyst.

  In recent years, in order to further improve energy efficiency and solve environmental problems, attempts have been made to clean exhaust gas by using a fuel cell as a power source for automobiles. ing. In particular, development of a polymer electrolyte fuel cell (PEFC) as a fuel cell for a fuel vehicle (FCHV) has been rapidly progressing.

  A fuel cell is a power generator that supplies fuel to the anode and oxidant to the cathode, takes out the potential difference between the anode and cathode as voltage, and supplies it to the load. Hydrogen is commonly used as the anode fuel, and oxidant is generally used as the oxidant. For this, oxygen in the air is used. A fuel cell is composed of an anode and a cathode and an electrolyte sandwiched between them. In a polymer electrolyte fuel cell, an ion exchange membrane is used as an electrolyte. Specifically, an electrolyte membrane / electrode assembly in which a catalyst layer is formed on both surfaces of an ion exchange membrane as an electrolyte, and an anode gas diffusion layer and a cathode gas diffusion layer are integrally formed on the outside of the catalyst layer, respectively. A unit cell composed of a barrier plate, an electrolyte membrane / electrode assembly, and a barrier plate laminate is formed by stacking several tens to several hundreds of cells so as to obtain a desired voltage according to the application. Yes.

  In such a fuel cell, when hydrogen reaches the anode catalyst layer, protons and electrons are generated by an electrochemical reaction process. Protons generated here move sequentially in the electrolyte and reach the cathode. On the other hand, electrons are sent to the cathode via an external load. In the cathode catalyst layer, electrons sent via an external load, oxygen in the air as an oxidant, and protons that have moved through the electrolyte combine to form water through an electrochemical reaction process. .

  Conventionally, as a catalyst for such a fuel cell, a catalyst based on a noble metal such as platinum, which is expensive and has a problem in terms of resources, has been used for both the cathode and the anode. The amount of platinum used for the exhaust gas purification catalyst of gasoline cars is considerably larger than that of platinum.

  Therefore, in order to commercialize fuel cells, development of fuel cell catalysts that can be put into practical use at low cost, replacing catalysts based on precious metals such as platinum, which are problematic in terms of price and resources. Is one of the essential issues.

In the following Patent Document 1, it is described in the claims that an alloy composed of platinum element and an additive element such as tellurium element is used for the fuel cell catalyst, and PtTe ₂ is studied in Example 4. However, in this document, the group VIII element is limited to Pt, and there is no disclosure about ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), or iridium (Ir).
Non-patent documents 1 and 2 describe a catalyst composed of a ruthenium element and a tellurium element, but only a catalyst having an abundance ratio of ruthenium element and tellurium element of Ru / Te = 1 / 0.055 is disclosed. No catalyst is disclosed for the tellurium element ratio exceeding 0.055, and no suggestion is given.
Non-Patent Document 3 discloses LuxTey, but does not disclose specific values of x and y. Since the synthesis method is the same as in Non-Patent Document 1, it is speculated that only Ru ₁ Te _0.055 has been studied.
Non-patent documents 4 and 5 disclose Mo ₄ Ru ₂ Te ₈ , Mo ₅ Rh ₁ Te ₈ , and Mo _5.4 Os _0.6 Te ₈ . However, it does not disclose any description that it is desirable that the abundance ratio of transition metals (Ru, Rh, Os) other than Te element and Mo is in a specific region.

JP-A-10-92441

Electrochimica Acta 47, 2002, 3807-3814 Journal of Physical Chemistry B 106 (7), 2002, 1670-1676 Nuclear Instruments & Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment, 448 (1-2), 2000, 323-326. Journal of Applied Electrochemistry 25 (11), 1995, 1004-1008 J Chim Phys Phys Chim Biol 93 (4), 1996, 702-710

As described in Document 1, it is known that an alloy of platinum and tellurium can be used as a fuel cell catalyst. However, this fuel cell catalyst uses platinum which is expensive and has problems in terms of resources. The problem of developing a catalyst for a fuel cell that can be used practically at low cost instead of a catalyst mainly composed of noble metals such as platinum cannot be solved.
The present invention provides a fuel cell catalyst that exhibits an excellent catalytic action that is inexpensive and can be substituted for a noble metal catalyst such as platinum, and a fuel cell electrode and a fuel cell using the fuel cell catalyst. Objective.

The fuel cell catalyst according to the first aspect includes tellurium (Te) and ruthenium (Ru ), and when the composition is expressed as Ru ₁ Te _X , 1 <X <4. .

The fuel cell catalyst of the second aspect is selected from the group consisting of rhodium (Rh), palladium (Pd), osmium (Os), and iridium (Ir) in addition to tellurium (Te) and ruthenium (Ru). When at least one element L is included and the composition is expressed as L _Y Ru ₁ Te _X , 1 <X and 0 <Y ≦ 10.

  The fuel cell electrode material of the third aspect and the fuel cell electrode of the fourth aspect have the catalyst of the first or second aspect.

  The fuel cell of the fifth aspect has the electrode of the fourth aspect.

As a result of intensive investigations in view of the above circumstances, the present inventors have a high catalytic activity by using an alloy or a compound composed of a group VIII element such as ruthenium and tellurium, and can be substituted for a noble metal catalyst such as platinum. It has been found that a fuel cell catalyst having the following can be obtained. Further, it has been found that by attaching this to a substrate, a fuel cell catalyst can be obtained that is inexpensive, has a higher catalytic activity, and has a practical utility that can replace a noble metal catalyst such as platinum.
The present invention has been completed based on such knowledge, and the gist thereof is as follows.

[1] A fuel cell catalyst comprising tellurium (Te) and ruthenium (Ru ) , wherein the composition is expressed as Ru ₁ Te _X , 1 <X <4 .
[2 ] A fuel cell catalyst according to [1], which contains RuTe ₂ .
[ 3 ] In [1], in addition to tellurium (Te) and ruthenium (Ru) , at least one selected from the group consisting of rhodium (Rh), palladium (Pd), osmium (Os), and iridium (Ir) A catalyst for a fuel cell comprising a seed element L and having a composition expressed as L _Y Ru ₁ Te _X , wherein 1 <X and 0 <Y ≦ 10.
[ 4 ] The fuel cell catalyst according to [1], further including a substrate on which Te and Ru are deposited .
[5 ] The catalyst for a fuel cell according to [ 4 ], wherein the substrate is a carbon-based substrate .
[6 ] A fuel cell catalyst according to [1], wherein the fuel cell is a polymer electrolyte fuel cell .
[7 ] A fuel cell electrode material comprising an ion exchange membrane and a fuel cell catalyst layer of [1] formed on the ion exchange membrane .
[8 ] A fuel cell electrode material comprising an electrode gas diffusion layer and a fuel cell catalyst layer of [1] formed on the electrode gas diffusion layer .
[9 ] A fuel cell electrode material comprising a transfer film and a fuel cell catalyst layer of [1] formed on the transfer film .
[10 ] A fuel cell electrode comprising the fuel cell catalyst according to [1] .
[11 ] A fuel cell using the fuel cell electrode according to [ 10 ] .
[12 ] In the fuel cell according to [ 11 ], the fuel cell is a polymer electrolyte fuel cell .
[13 ] A method for producing a fuel cell catalyst according to [ 5 ], comprising the steps of mixing a carbon-based substrate, a Te precursor and a Ru precursor, and activating the precursor. method for producing a catalyst for a fuel cell characterized by having.
[14 ] A method for producing a fuel cell catalyst according to [ 5 ], comprising a step of mixing a carbon-based substrate and the fuel cell catalyst according to [1]. A method for producing a catalyst .
[15 ] The method for producing a fuel cell catalyst according to [ 13 ], further comprising a step of depositing a transition metal on the carbon-based substrate .
[16 ] The method for producing a fuel cell catalyst according to [ 14 ], further comprising a step of depositing a transition metal on a carbon-based substrate .
[17 ] A fuel cell stack containing the fuel cell catalyst according to [1] .
[18 ] A fuel cell system including the fuel cell stack according to [ 17 ] .

  INDUSTRIAL APPLICABILITY According to the present invention, for a practical fuel cell that exhibits good catalytic action and can be synthesized safely at low cost, which can be replaced with a noble metal catalyst such as platinum, which is expensive and problematic in terms of resources. Provided are a catalyst, a fuel cell electrode and a fuel cell using the fuel cell catalyst.

  According to the present invention, since a fuel cell using an inexpensive fuel cell catalyst is provided, the expansion and practical application of the fuel cell to a fuel vehicle, a stationary cogeneration system, and the like are promoted.

  Hereinafter, the present invention will be described in more detail. However, the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

[Fuel cell catalyst]
The fuel cell catalyst according to the first aspect of the present invention contains tellurium (Te), and further comprises ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), and iridium (Ir). The value of X when including one or more selected elements M and expressed as M ₁ Te _X is 0.2 <X <4. In the description of the first aspect, Te and the element M may be collectively referred to as an active component.

The catalyst for a fuel cell according to the second aspect of the present invention includes tellurium (Te), ruthenium (Ru), and rhodium (Rh), palladium (Pd), osmium (Os), and iridium (Ir) contained as necessary. ), The value of X when expressed as L _Y Ru ₁ Te _X is X> 0.2, and the value of Y is 0 <y ≦ 10. It is. In the description of the second aspect, Te, Ru, and element L may be collectively referred to as an active component.

  In any embodiment, the fuel cell catalyst of the present invention may be composed of only active components, and may further contain other transition metals. The active ingredient may be applied to the substrate.

  In the following, an element represented by M, that is, one or more elements selected from the group consisting of ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), and iridium (Ir) is represented by “ Sometimes referred to as “Group VIII metal”. One or more elements L selected from the group consisting of rhodium (Rh), palladium (Pd), osmium (Os), and iridium (Ir) may be referred to as “Group VIII metal other than Ru”.

  In addition, a fuel cell catalyst that is not coated with an active component and is substantially composed of only the active component is referred to as a “pure catalyst”, and a fuel in which the active component is deposited on the substrate. Battery catalysts are sometimes referred to as “adhered catalysts”.

<Active ingredient>
Next, the abundance ratio of tellurium (Te) element and group VIII metal element (M) in the active component of the fuel cell catalyst of the first embodiment will be described. When the composition of the active ingredient is described as M ₁ Te _X , X> 0.2, particularly preferably X> 1, X <4, preferably X <3, more preferably X <2.5. is there. If the abundance ratio X of the tellurium element is less than this range, the activity tends to be low, and if it exceeds this range, the activity is difficult to be produced. Two or more Group VIII metal elements (M) may be used. M ₁ Te _X represents the ratio of the total number of elements of the group VIII metal element M to the number of tellurium elements Te.

Next, the abundance ratio of tellurium (Te) element, ruthenium (Ru) element and group VIII metal (L) other than Ru in the active component of the fuel cell catalyst of the second embodiment will be described. When the composition of the active ingredient of the second aspect is described as L _Y Ru ₁ Te _X , X is X> 0.2, preferably X> 1, usually X <20, preferably X <15, More preferably, X <10, more preferably X <5, and particularly preferably X <3. If the abundance ratio of the tellurium element is below this range, the activity tends to be low, and if it exceeds this range, the activity is difficult to be produced.

Y is 0 <Y ≦ 10, preferably 0 <Y ≦ 5, more preferably 0 <Y ≦ 3. Two or more Group VIII metal elements (L) other than Ru may be used. L _Y Ru ₁ Te _X represents the ratio of the total number of group VIII metal elements L other than Ru, the number of elements of ruthenium element (Ru), and the number of elements of tellurium element (Te).

  In either of the first and second embodiments, the abundance ratio of each element in the catalyst is determined by inductively coupled plasma emission spectroscopy according to a conventional method by weighing the catalyst and then decomposing it by melting with alkali, adding the acid, and measuring the volume. It can be quantified by analytical methods.

  In any embodiment, the content of tellurium in the active ingredient is usually 5% or more by weight, more preferably 6% or more, still more preferably 10% or more, usually 96% or less, based on the whole active ingredient. Preferably it is 95% or less, More preferably, it is 93% or less, More preferably, it is 90% or less, More preferably, it is 87% or less. If the tellurium content in the active ingredient is below this range, the activity tends to be low, and if it exceeds this range, the activity is difficult to be produced.

  In the first and second embodiments, the total content of Group VIII metals in the active ingredient, that is, ruthenium, rhodium, palladium, osmium, and iridium is usually 1% or more, preferably 5 with respect to the whole active ingredient. % Or more, more preferably 7% or more, further preferably 10% or more, more preferably 13% or more, usually 95% or less, preferably 90% or less, more preferably 88% or less, still more preferably 85% or less. . If the content of the group VIII metal in the active ingredient is below this range, the activity tends to be low, and if it exceeds this range, the activity is difficult to be produced.

  In the first and second embodiments, the active ingredient may contain one kind of Group VIII metal alone or may contain two or more kinds. The active ingredient preferably contains ruthenium or rhodium as the Group VIII metal, and particularly preferably contains ruthenium as the Group VIII metal.

  The active ingredient can also contain ingredients other than tellurium elements and Group VIII metals as long as the effects of the present invention are not impaired.

In the active ingredient of the first and second embodiments, tellurium may be Te element, oxide such as TeO ₂ and TeO ₃ , oxo acid such as H ₂ TeO ₃ and H ₆ TeO ₆ , TeCl ₂ and TeBr. _It may take the form of an inorganic compound such as chloride such as ₂ and an organic compound such as tellurophen. Group VIII metals can also take the form of bonding with organic compounds in addition to inorganic compounds such as metal elements, oxides, and chlorides. For example, ruthenium may be a Ru element, an oxide such as RuO or RuO ₂ , a chloride such as RuCl ₃ · xH ₂ O, an inorganic compound such as Ru (NO) (NO ₃ ) ₃ , Ru (acac) ₃ and Ru ₃ (CO) ₁₂ may be combined with an organic compound such as ₁₂ .

  These tellurium components and group VIII metal components constituting the active component may be present without any bond, or may be present with a bond. In the case where these elements have a bond and the elements are directly bonded to each other, the active component may be a so-called alloy.

Specific examples of the active component having an alloy form include RuTe ₂ , RuTe, Ru ₂ Te, OsTe ₂ , RhTe, RhTe ₂ , Rh ₃ Te ₂ , Rh ₃ Te ₄ , Rh ₃ Te ₈ , IrTe ₂ , _{Ir 3 Te 8, PdTe, Pd} 3 Te 2, PdTe 2, Pd 9 Te 4, Pd 2.5 Te, Pd 3 Te, Pd 2 Te, Pd 20 Te 7, Pd 8 Te 3, Pd 7 Te 2, Pd 7 Te ₃ , Pd ₄ Te, Pd ₁₇ Te _{4 and the} like. Among them, RuTe ₂ , RuTe and Ru ₂ Te are preferable, and RuTe ₂ is particularly preferable. It may be in the form of an alloy in which tellurium and two or more elements of group VIII metals are bonded.

  The presence form () of the element in the active ingredient can be specified by X-ray diffraction (XRD). That is, for example, the existence form of an element can be specified by irradiating an active ingredient deposited on a substrate described later with X-rays (Cu-Kα rays) and observing the diffraction spectrum thereof.

  Examples of the measurement apparatus and measurement conditions include, but are not limited to, the following.

Measuring device X-ray powder analysis device / PANallytical PW1700
Measurement conditions X-ray output (Cu-Kα): 40 kV, 30 mA
Scanning axis: θ / 2θ
Measurement range (2θ): 3.0 ° to 90.0 °
Measurement mode: Continuous
Reading width: 0.05 °
Scanning speed: 3.0 ° / min
DS, SS, RS: 1 °, 1 °, 0.20mm

Specifically, RuTe ₂ has 21.808 °, 27.920 °, 31.287 °, 32.716 °, 43.369 ° as 2θ (± 0.3 °) peaks of X-ray diffraction. Those giving characteristic peaks such as 45.203 °, 48.322 °, 51.509 °, 53.981 °, 56.910 °, 68.565 °, 21.767 °, 26.189 °, 27 .877 °, 31.249 °, 32.658 °, 33.847 °, 36.719 °, 39.822 °, 43.308 °, 44.377 °, 45.177 °, 45.801 °, 48 Those giving characteristic peaks such as 244 °, 50.117 °, 50.661 °, 51.426 °, 27.857 °, 31.271 °, 34.344 °, 39.873 °, 47. 123 °, 49.353 °, 51.53 °, 53.614 °, 57.636 °, 65.236 °, 67.032 °, 68.881 °, 72.414 °, 77.547 °, 80.922 °, 82.608 °, 85.948 Those that give a characteristic peak such as °.

<Pure catalyst shape>
There is no particular limitation on the shape of the pure catalyst made of the active component not deposited on the substrate, but it is most generally particulate. The average particle size of the particulate pure catalyst is usually 100 μm or less, preferably 1000 nm or less, more preferably 500 nm or less, especially 300 nm or less, usually 0.5 nm or more, preferably 1.0 nm or more, more preferably 2.0 nm. That's it. If the particle size of the pure catalyst is less than this range, it becomes unstable and easily deactivates, and if it exceeds this range, it becomes difficult to obtain high activity.

  In addition, the average particle diameter of the pure catalyst is measured by unifying the direction of measuring the length of the particle diameter with a scanning electron microscope (SEM) or transmission electron microscope (TEM) and measuring the particle length in that direction. This is shown as an average value.

<Substrate>
The deposition catalyst has a substrate and an active component deposited and held on the substrate. In order to electrically connect the active component, the substrate preferably has high conductivity.

  The substrate is preferably a carbon-based substrate having high conductivity.

  The carbon-based substrate is not particularly limited, and may be, for example, carbon black, carbon nanotube, carbon nanohorn, carbon nanocluster, fullerene, pyrolytic carbon, activated carbon, or the like. The carbon-based substrate may be a vapor-grown carbon fiber (Vapor Growth Carbon Fiber: hereinafter sometimes abbreviated as “VGCF”) by a vapor-phase method. It has moderate elasticity and is suitable.

  Among these carbon-based substrates, carbon black is industrially advantageous in terms of conductivity, availability, and cost. Examples of carbon black include channel black, furnace black, thermal black, acetylene black, oil furnace black, and gas furnace black. These carbon-based substrates can be used singly or in combination of two or more.

The specific surface area of the substrate is not particularly limited, but is usually 5 m ² / g or more, preferably 100 m ² / g or more, more preferably 150 m ² / g or more, and usually 5000 m ² / g or less, preferably 2000 m ² / g. The following is preferable. If the specific surface area is too small, the effective area for depositing the active ingredient is reduced, and the reaction field is reduced, so that sufficient catalytic activity cannot be obtained. Moreover, when the specific surface area is excessively large, the pore diameter of the substrate may be small, and even if the active component is deposited in the small pores, sufficient catalytic activity cannot be obtained. The specific surface area of the substrate is measured by the BET method.

  The form of the substrate is not particularly limited, but the most commonly used is a powder form.

<Adhesion of active ingredient to substrate>
In the present invention, the state in which the active component is applied to the substrate refers to a state in which the active component and the substrate are in contact with each other so as to obtain electrical conductivity. Therefore, the active ingredient can be applied to the substrate by simply mixing the active component and the substrate. However, as described later, after mixing the active compound supply compound and the substrate, the mixture is calcined and coated. It is preferable to wear. Alternatively, the substrate and the active component may be mixed and then fired. In the following, the state in which the active ingredient is mixed with the active ingredient supply compound or the active ingredient and then baked to deposit the active ingredient is referred to as “supporting”.

  The shape of the active ingredient applied to the substrate is not particularly limited, but the most common is a particulate form. The average active particle size of the particulate active ingredient is usually 100 μm or less, preferably 1000 nm or less, more preferably 500 nm or less, especially 300 nm or less, usually 0.5 nm or more, preferably 1.0 nm or more, more preferably 2 It is desirable that it is 0.0 nm or more. If the particle size of the active ingredient is below this range, it becomes unstable and easily deactivated, and if it exceeds this range, it becomes difficult to obtain high activity.

  The average particle size of the active ingredient deposited on the substrate is determined by unifying the direction in which the particle length is measured with a scanning electron microscope (SEM) or transmission electron microscope (TEM). The particle length is measured and indicated as an average value.

  In order to deposit such a small average particle size active ingredient on a substrate, the production method may be devised as described later. Among these, it is preferable to control the state of crystal growth by lowering the firing temperature after mixing the substrate and the active component and shortening the firing time.

The weight ratio of active ingredient / (active ingredient + substrate) indicating the deposition ratio of the active ingredient to the substrate is not particularly limited, but is usually 10 ⁻⁵ or more, preferably 0.001 or more, more preferably It is 0.01 or more, especially 0.05 or more, and usually 0.95 or less, preferably 0.4 or less, and especially 0.3 or less. If the deposition ratio of the active ingredient is below this range, the desired activity cannot be obtained, and if it exceeds this range, the effect of improving the activity due to deposition becomes difficult.

<Other catalyst components>
In the present invention, a transition metal may be further deposited on the substrate as long as the effects of the present invention are not impaired.

This transition metal (hereinafter sometimes referred to as “other catalyst component”) is an element belonging to the fourth to sixth periods of groups IIIA to VIIA, VIII, and IB of the periodic table, and titanium ( Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), yttrium (Y), zirconium (Zr), niobium ( Nb), molybdenum (Mo), lanthanum (La), europium (Eu), gold (Au), cerium (Ce), tantalum (Ta), tungsten (W), rhenium (Re), praseodymium (Pr), neodymium ( Nd) is exemplified. The transition metal is preferably one having a positive standard electrode potential E ° (25 ° C.) in an aqueous solution represented by the following electrochemical equilibrium formula: oxidant + ne ⁻ = reduced form. This is because elution due to oxidation is unlikely to occur as a natural property of metals, and there is little deterioration of the catalyst due to it. Specific examples of such a transition metal include gold and silver.

  However, in order to make the catalyst more industrially advantageous, it is better to reduce the number of expensive catalyst components as much as possible.

  Although platinum (Pt) can be used in combination as the transition metal, platinum is expensive, so it is desirable that the addition amount be small. When platinum is added, specifically, the weight ratio of the total platinum component / active ingredient is usually 0.001 or more, preferably 0.01 or more, more preferably 0.05 or more, and usually 0.4 or less, preferably Is preferably 0.3 or less, and more preferably 0.2 or less.

  In addition, the following shows the electrochemical equilibrium formula of main transition metals and the standard electrode potential E ° (25 ° C.).

  These transition metals as other catalyst components may be used alone or in combination of two or more.

Specific examples in which the transition metal and the active component are used in combination include the following i) to v).
i) The active ingredient is mixed with other catalyst components to the substrate.
ii) Other catalyst components are supported on the substrate together with the active components.
iii) The active component supported on the substrate is mixed with other catalyst components.
iv) The other catalyst component supported on the other substrate is mixed with the active component.
v) The other catalyst component supported on the other substrate is mixed with the active component supported on the substrate.

  The total transition metal / active component weight ratio is usually 0.001 or more, preferably 0.01 or more, especially 0.05 or more, usually 0.5 or less, preferably 0.4 or less, especially 0.3. The following is preferred. If this weight ratio is less than this range, it is difficult to obtain the desired activity, and if it exceeds this range, it is difficult to improve the activity.

  The transition metal is preferably in the form of powder. The average particle size of the powder is usually 1000 nm or less, preferably 500 nm or less, and more preferably 300 nm or less, and usually 0.5 nm or more. When the average particle size is less than this range, the catalyst becomes unstable and easily deactivates, and when it exceeds this range, it is difficult to obtain high activity.

In the fuel cell catalyst of the present invention, a metal component other than the transition metal element may be contained in an amount of several weight percent or less based on the weight of the active component.

  A catalyst containing an active component and a transition metal, in particular, a catalyst having an active component and a transition metal supported on a substrate has high catalytic activity. This is presumably because the transition metal functions as a cocatalyst for the active component and the activity is improved.

<Manufacture of pure catalyst>
There is no particular limitation on the method for synthesizing the pure catalyst of the first aspect composed only of the active component not deposited on the substrate, and any known method can be used.

  For example, an element supply compound as an active ingredient, that is, a precursor of the active ingredient is dissolved or dispersed in a solvent such as water in a predetermined molar ratio, and after filtration or evaporation of the solvent, the precursor is added as necessary. It is prepared by applying an activation step (for example, reduction treatment).

The precursor of each element is not particularly limited as long as it can be thermally decomposed. Tellurium precursors include tellurium powder (Te), halides such as TeCl ₂ , TeBr ₂ and TeCl ₄ , oxides such as TeO ₂ and TeO ₃ , and oxo acids such as H ₂ TeO ₃ and H ₆ TeO _6. Inorganic salts such as

Moreover, as precursors of ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), in addition to these halides, oxides, inorganic salts, organic acid salts, etc., Examples include compounds that bind to organic compounds. Specific examples of the ruthenium compound include halides such as RuCl ₃ · xH ₂ O and RuBr ₃ , Ru (SO ₄ ) ₂ , Ru (NO) (NO ₃ ) _3, K ₂ RuO ₄ · H ₂ O and the like. Examples thereof include inorganic salts, organic acid salts such as Ru ₂ (OCH ₃ CO) ₄ , and organic compounds such as ruthenium acetylacetonate (Ru (acac) ₃ ). Examples of the rhodium compound include halides such as RhCl ₃ · xH ₂ O and RhBr ₃ , inorganic salts such as KRh (SO ₄ ) ₂ · 12H ₂ O, Rh (NO ₃ ) ₃ · 2H ₂ O, and Rh (OCH ₃ CO ) Organic acid salts such as ₃ . Examples of the palladium compound include halides such as PdCl ₂ , PdCl ₂ .2H ₂ O, PdF ₂ , PdCl ₄ , K ₂ PdCl ₄ , K ₂ PdCl ₆ , inorganic salts such as Pd (NO ₃ ) ₂ , Pd (OCH _3). CO) _{2 and} other organic acid salts. Examples of the osmium compound include halides such as OsCl ₃ and K ₂ OsCl ₆ , and oxides such as OsO ₂ . Examples of the iridium compound include halides such as IrCl ₃ and IrBr ₃ , oxides such as IrO ₂ , and inorganic salts such as Ir (SO ₄ ) ₂ .

  These precursors may be used individually by 1 type, and 2 or more types may be mixed and used for them.

In order to produce a RuTe _X pure catalyst, for example, RuCl ₃ or Ru (acac) ₃ and H ₆ TeO ₆ are mixed in a desired molar ratio (RuCl ₃ , Ru (acac) _3, etc., the molar ratio of H ₆ TeO ₆ is Usually 0.2 or more, preferably 1 or more, usually 10 or less, preferably 4 or less, dissolved in water at a blending ratio, and a predetermined time (usually 10 minutes or more, preferably 30 minutes or more, usually 50 hours or less). , Preferably 30 hours or less) and then, if necessary, at a predetermined temperature (usually 60 ° C. or higher, preferably 100 ° C. or higher, usually 300 ° C. or lower, preferably 200 ° C. or lower) for a predetermined time (usually 10 minutes or longer). (Preferably 30 minutes or more, usually 50 hours or less, preferably 30 hours or less) Heating or refluxing, and then obtaining a precipitate by an evaporator. This is air-dried at room temperature, and then in an inert gas atmosphere such as nitrogen or argon for a predetermined time (usually 10 minutes or more, preferably 30 minutes or more, usually 50 hours or less, preferably 30 hours or less), a predetermined temperature (usually 100 The drying treatment is carried out at a temperature of not less than 200 ° C, preferably not less than 200 ° C, usually not more than 1000 ° C, preferably not more than 800 ° C. Next, a predetermined time (usually 10 minutes or more, preferably 30 minutes or more, usually 50 hours or less, preferably 30 hours or less), a predetermined temperature (usually 100 ° C or more, preferably 200 ° C or more, more preferably 300 ° C or more). In general, an inert gas such as nitrogen or Ar may be mixed under an air stream containing hydrogen at 1000 ° C. or lower, preferably 800 ° C. or lower. The hydrogen concentration in the inert gas is not particularly limited, but 1 % Or more, preferably 10% or more, 100% or less, or 80% or less). Thereby, an active component containing Ru and Te, that is, a pure catalyst can be obtained.

Pure catalysts other than RuTe _X can be produced in the same manner.

  Thereafter, in an inert gas atmosphere having a low oxygen concentration (for example, an oxygen concentration of about 5 wt% or less, especially about 2 wt% or less), a predetermined time (usually several tens of minutes, preferably 30 minutes or more, usually Passivation treatment may be performed to form a passive film by treatment at a predetermined temperature (usually around room temperature) for 10 hours or less, particularly 5 hours or less.

<Manufacture of deposited catalyst>
The deposition catalyst of the second embodiment is produced by depositing an active component on a substrate. Here, the active component may be applied to the substrate by, for example, a loading method in which the active component or a precursor of the active component is mixed and baked with the substrate, a mixing method in which the active component and the substrate are simply mixed, and other impregnations. It can carry out by well-known methods, such as a method, a precipitation method, and an adsorption method.

For example, the deposited catalyst is prepared by dissolving or dispersing a precursor of each element in a solvent such as an aqueous solution in a desired molar ratio, and impregnating the substrate with the solution or immersing the substrate in the solution, followed by filtration. Alternatively, it is prepared by depositing the precursor on the substrate by distilling off the solvent and, if necessary, activating the precursor of the active ingredient (for example, reduction treatment). In addition, the precursor similar to the compound used for manufacture of a pure catalyst can be used for the precursor of an active component. Among these, RuCl ₃ · xH ₂ O, Ru (acac) _{3 and} Ru (NO) (NO ₃ ) ₃ are preferable as the ruthenium precursor, and H ₆ TeO ₆ is preferable as the tellurium precursor.

Next, an example of a method for producing a deposition catalyst containing Ru and Te as active components will be described. RuCl ₃ or Ru _{(acac) 3} and H ₆ TeO ₆ blending ratio corresponding to the molar ratio of the desired (RuCl _3, Ru _(acac) molar ratio of H ₆ TeO ₆ for like ₃ is generally 0.2 or more, Preferably, it is dissolved in water at 1 or more, usually 10 or less, preferably 4 or less, and a predetermined amount of a substrate such as carbon black is mixed therewith, and a predetermined time (usually 10 minutes or more, preferably 30 minutes or more, usually 50). Or less, preferably 30 hours or less). In this case, ultrasonic treatment may be performed. Next, if necessary, a predetermined temperature (usually 60 ° C or higher, preferably 100 ° C or higher, usually 300 ° C or lower, preferably 200 ° C or lower) for a predetermined time (usually 10 minutes or longer, preferably 30 minutes or longer, usually 50 ° C). Heating or refluxing for a period of time or less, preferably 30 hours or less). Thereafter, a precipitate is obtained by filtration or an evaporator. This is air dried at room temperature. Next, a predetermined time (usually 10 minutes or more, preferably 30 minutes or more, usually 50 hours or less, preferably 30 hours or less) under a inert gas atmosphere such as nitrogen or argon, a predetermined temperature (usually 100 ° C. or more, preferably After drying at 200 ° C. or higher, usually 1000 ° C. or lower, preferably 800 ° C. or lower), a predetermined time (usually 10 minutes or longer, preferably 30 minutes or longer, usually 50 hours or shorter, preferably 30 hours or shorter), a predetermined temperature (Normally 100 ° C or higher, preferably 200 ° C or higher, more preferably 300 ° C or higher, usually 1000 ° C or lower, preferably 800 ° C or lower). The hydrogen concentration in the inert gas is not particularly limited, but is heated at 1% or more, preferably 10% or more, 100% or less, or 80% or less. As a result, an adherent catalyst in which an active component containing Ru and Te is supported on a substrate is obtained.

  Thereafter, in an inert gas atmosphere having a low oxygen concentration (for example, an oxygen concentration of about 5 wt% or less, especially about 2 wt% or less) for a predetermined time (usually several tens of minutes, preferably 30 minutes or more, usually 10 It is also possible to perform a passivation treatment for forming a passive film by treatment at a predetermined temperature (usually around room temperature) for a time or less, particularly 5 hours or less.

  Further, the active ingredient can be applied to the substrate by preparing the active component in advance by the above-described known method, mixing it with the substrate, and kneading the mixture with a mortar or the like. This mixing may be dry or wet, but is preferably wet mixed using a medium such as water and then dried at about 100 to 200 ° C.

  Among the above-described catalyst production methods, a support method in which a carbon base and a component selected from an active component and a precursor of the active component are mixed and then calcined is preferable. This calcination can improve the activity of the resulting catalyst. The reason why the activity can be improved by firing in this way is not necessarily clear, but since the active component is adhered to the carbon-based substrate, the sintering of the active component is suppressed during firing, and the activity is reduced. Is estimated to be due to the improvement.

  When the above-mentioned transition metal is applied to the substrate together with the active component, the transition metal may be applied simultaneously in the active component application step, and the transition metal is applied before or after the active component application step. May be. Here, the “active component deposition step” includes the treatment process for depositing the active component, that is, the entire process from the addition of the active component precursor to the provision of the active component.

  As transition metal precursors for depositing transition metals on the substrate, oxides, inorganic acid salts such as nitrates, sulfates and carbonates, organic acid salts such as acetates, halides, hydrides, Examples include carbonyl compounds, amine compounds, olefin coordination compounds, phosphine coordination compounds, and phosphite coordination compounds. These may be used alone or in combination of two or more.

  In order to deposit the transition metal together with the active component on the substrate, for example, a transition metal compound such as chloride is dissolved in the catalyst in which the active component containing Ru and Te synthesized by the method described above is supported on the substrate. The solution is added and allowed to stand for a predetermined time (usually 10 minutes or more, preferably 30 minutes or more, usually 50 hours or less, preferably 30 hours or less), and then the solvent is distilled off by an evaporator. In this case, ultrasonic treatment may be performed. Next, under an air stream containing hydrogen (inert gas such as nitrogen or Ar may be mixed, the hydrogen concentration in the inert gas is not particularly limited, but is 1% or more, preferably 10% or more, 100 % Or less, or 80% or less) at a predetermined temperature (usually 100 ° C. or higher, preferably 150 ° C. or higher, usually 800 ° C. or lower, preferably 500 ° C. or lower) for a predetermined time (usually 10 minutes or longer, preferably 30 minutes or longer). Usually 50 hours or less, preferably 30 hours or less). As a result, an adherent catalyst in which both the active component containing Ru and Te and the transition metal are supported on the substrate is obtained.

  Thereafter, in an inert gas atmosphere having a low oxygen concentration (for example, an oxygen concentration of about 5 wt% or less, especially about 2 wt% or less) for a predetermined time (usually several tens of minutes, preferably 30 minutes or more, usually 10 It is also possible to perform a passivation treatment for forming a passive film by treatment at a predetermined temperature (usually around room temperature) for a time or less, particularly 5 hours or less.

  As described above, the transition metal may be used as it is by mixing it with the substrate to which the active component is applied, or may be used by mixing the active component with the substrate to which the transition metal is applied.

[Fuel cell electrode and fuel cell]
The fuel cell electrode of the present invention contains the above-described fuel cell catalyst of the present invention. The fuel cell of the present invention uses such a fuel cell electrode of the present invention.

  In the fuel cell according to the present invention, as described above, fuel is supplied to the anode and oxidant is supplied to the cathode, the potential difference between the anode and cathode is taken out as a voltage, and power is supplied to the load. This power generation device includes an anode electrode, a cathode electrode, and an electrolyte sandwiched therebetween. In a polymer electrolyte fuel cell, an ion exchange membrane is used as an electrolyte. Solid polymer fuel cells include both PEFC fuel cells using hydrogen as a fuel and direct methanol fuel cells (DMFC) using methanol and water.

  In the case of a PEFC type fuel cell in which a catalyst layer is formed on both surfaces of an ion exchange membrane as an electrolyte, and a gas diffusion layer is formed outside the catalyst layer, the anode gas diffusion layer and the cathode gas diffusion layer are integrally formed. An electrolyte membrane / electrode assembly is used. In the case of a DMFC type fuel cell, an electrolyte membrane / electrode assembly in which a methanol aqueous solution current collector and a cathode gas diffusion layer are integrally formed is used. The electrolyte membrane / electrode assembly is provided with a partition plate on the diffusion layer side, and a plurality of unit cells including the partition plate, the electrolyte membrane / electrode assembly, and the partition plate are stacked until a desired voltage is obtained according to the application. To form a fuel cell stack. Usually, several tens to hundreds of unit cells are stacked to form a fuel cell stack.

  As the catalyst for forming the catalyst layer of the electrolyte membrane / electrode assembly, the fuel cell catalyst according to any of the first and second embodiments described above is used.

  An ion exchange membrane as an electrolyte is only required to have a cation exchange capacity, but it is practically desired to withstand an oxidation-reduction atmosphere at a temperature of about 80 to 100 ° C., which is a use temperature of a fuel cell. Alkyl sulfonic acid resins are exclusively used. Specific examples include perfluoroalkylsulfonic acid resin membranes such as Nafion (registered trademark manufactured by DuPont), Flemion (registered trademark manufactured by Asahi Glass Co., Ltd.), and Aciplex (registered trademark manufactured by Asahi Kasei Co., Ltd.).

  The ion exchange membrane preferably has a thickness of about 10 μm or more and several hundreds of μm or less, but it is desirable to make the thickness thinner in order to reduce the electric resistance. Taking Nafion as an example, Nafion 115 having a thickness of about 120 μm is often used. However, an electrolyte membrane having a thickness of 30 to 50 μm including a reinforcing material has begun to be developed, and these can be used similarly. .

  The diffusion layer of the PEFC type fuel cell supplies hydrogen at the anode and air at the cathode, and also has a function as a current collector for taking out the generated voltage. Therefore, the diffusion layer is preferably made of a material that is an excellent electronic conductor, allows both hydrogen and air gases to flow through, and can withstand the working atmosphere. As a material constituting the anode gas diffusion layer and the cathode gas diffusion layer, a carbon porous body such as carbon paper or carbon cloth having a thickness of usually about 100 to 500 μm, preferably about 100 to 200 μm is used. Similarly, the material of the methanol aqueous solution current collector of the DMFC type fuel cell is selected from materials in which the methanol aqueous solution circulates and can withstand the use atmosphere, and the thickness is usually 100 to 500 μm, preferably about 100 to 200 μm. A carbon porous body such as paper or carbon cloth is used.

  When an electrolyte membrane / electrode assembly is used in a fuel cell, a partition plate made of a material such as carbon, and in some cases, stainless steel, titanium, etc. is usually disposed behind the membrane to prevent hydrogen and air from mixing. In general, the partition plate is formed with grooves for the purpose of uniform and stable supply of hydrogen and air.

  Although there is no restriction | limiting in particular as a method of producing the electrolyte membrane / electrode assembly of the fuel cell of this invention, For example, the following methods are mentioned.

  Next, an example of a method for forming the cathode side catalyst layer and the anode side catalyst layer on the ion exchange membrane will be described. First, the fuel cell catalyst according to the first or second aspect is put in a suitable container, and a Nafion solution (concentration 5 wt%, manufactured by Aldrich) in which Naponion (registered trademark) manufactured by DuPont is dissolved, and a medium such as alcohol or water. To prepare a catalyst slurry. At this time, it is more preferable to apply ultrasonic vibration in order to promote the dispersion well. The concentration of the fuel cell catalyst of the present invention in the catalyst slurry is preferably about 1 to 50 g / L in order to obtain a desired dispersibility. Of course, a binder such as polytetrafluoroethylene (PTFE) may be added to the slurry in the range of about 3 to 30% by weight for the purpose of imparting water repellency or preventing the catalyst layer from peeling off. In addition, when the contents are to be agglomerated and made into a paste, the alcohol has 2 to 5 carbon atoms such as ethanol or isopropyl alcohol, preferably a lower alcohol having about 2 to 4 carbon atoms, or 2 to 5 carbon atoms such as ethylene glycol, preferably A polyhydric alcohol having about 2 to 4 carbon atoms can be added and aggregated so as to have a ratio of 0.25 to 1.0 with respect to water.

  The catalyst slurry thus obtained is deposited on an ion exchange membrane, a gas diffusion electrode material or a transfer film, and then dried to form a cathode side catalyst layer and an anode side catalyst layer.

Specifically, the cathode side catalyst layer and the anode side catalyst layer are respectively formed on the ion exchange membrane or the gas diffusion electrode material by any one of the following methods a) to d).
a) Spray the catalyst slurry on the ion exchange membrane to be used and dry it.
b) Spray the catalyst slurry on a gas diffusion electrode material such as carbon paper and dry.
c) Spray the catalyst slurry onto a transfer film material such as a tetrafluoroethylene-hexafluoropropylene copolymer (FEP) film (development treatment) and dry it. The surface opposite to the transfer film surface is desired, such as Nafion. The catalyst layer is transferred by appropriately pressing on the ion exchange membrane.
d) Similarly to c), after the catalyst slurry is spread on the FEP film, the slurry is covered with a gas diffusion electrode material such as carbon paper and dried.

In any of the cathode side catalyst layer and the anode side catalyst layer, the active component adhesion amount (basis weight) is usually 0.01 mg / cm ² or more, preferably 0.1 mg / cm ² or more, usually 1 g / cm ² or less, It is preferably 20 mg / cm ² or less, and most preferably about 10 mg / cm ² or less. If the amount of the active component attached is less than this range, sufficient catalytic activity cannot be obtained, and if it is more than this range, it is difficult to form an electrolyte membrane / electrode assembly.

  The catalyst layer may be formed on the ion exchange membrane and then laminated with the anode gas diffusion layer material or the cathode gas diffusion layer material. The catalyst layer may be formed on the anode gas diffusion layer material or the cathode gas diffusion layer material. May be laminated with an ion exchange membrane. The laminated body is preliminarily pressure-molded and then pressure-heat-molded with a press to obtain an electrolyte membrane / electrode assembly. In this joined body, the above-mentioned cathode-side catalyst layer is formed on one surface of the ion exchange membrane, the anode-side catalyst layer is formed on the opposite surface of the ion-exchange membrane, and the outer sides of both catalyst layers. The gas diffusion layers constituting the anode and the cathode are respectively laminated.

  In addition, when press-molding a laminated body preliminarily, it is preferable to set temperature and pressure lower than the conditions of the main molding and to set the time short as long as the collapse of the catalyst layer is prevented. This is because the catalyst particles and the gas diffusion layer porous body do not cause compression failure.

  In the fuel cell system for PEFC of the present invention, in addition to the above fuel cell stack that obtains an electromotive force by an electrochemical reaction and a compressor that supplies compressed air as an oxygen-containing gas, hydrogen as a fuel gas is compressed to a high pressure. Has a hydrogen cylinder to store. In addition, a catalytic combustor that combusts exhaust hydrogen and exhaust air that have not been used for power generation in the fuel cell stack may be provided as necessary. Further, hydrogen may be supplied by a reforming reaction such as methanol, natural gas, or methane. In that case, the fuel cell system uses a tank of methanol, natural gas or methane, a water tank, a mixer of methanol and water, an evaporator for evaporating methanol aqueous solution, etc. instead of a hydrogen cylinder, a reforming reaction. A reformer to perform is provided. Furthermore, in order to prevent poisoning of the fuel cell by carbon monoxide contained in the hydrogen gas after the reforming reaction, a carbon monoxide reduction device may be provided.

  In addition, the DMFC fuel cell system of the present invention includes a fuel cell stack that obtains an electromotive force by an electrochemical reaction, a compressor that supplies compressed air as an oxygen-containing gas, and a methanol aqueous solution container that is fuel. The aqueous methanol solution is sent to the anode electrode of the fuel cell stack by a feed pump. The aqueous methanol solution may be supplied to the anode electrode after being heated and vaporized by an evaporator in advance. In addition, an aqueous methanol solution not used for power generation in the fuel cell stack may be collected and returned to the aqueous methanol solution container. The methanol aqueous solution may be collected using a gas-liquid separator when necessary.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited by a following example.

In the following examples and comparative examples, XRD analysis of the prepared catalysts was performed under the following conditions.
[Powder XRD analysis]
Measuring device X-ray powder analysis device / PANallytical PW1700
Measurement conditions X-ray output (Cu-Kα): 40 kV, 30 mA
Scanning axis: θ / 2θ
Measurement range (2θ): 3.0 ° to 90.0 °
Measurement mode: Continuous
Reading width: 0.05 °
Scanning speed: 3.0 ° / min
DS, SS, RS: 1 °, 1 °, 0.20mm

  In the following examples and comparative examples, the performance (catalytic activity) of the produced cathode electrode was measured by the following cyclic voltammetry (CV) measurement.

[CV measurement]
Cyclic voltammetry (CV) measurement was performed under the condition that oxygen was not rate-controlled while bubbling nitrogen or air into the electrolytic solution using a stopper capable of keeping hermeticity in the electrolytic cell. The measurement conditions are as follows.
Electrolyte: 1.0 MH ₂ SO ₄ aqueous solution Scan speed: 5 mV / sec Scan range: 100 to 700 mV
Counter electrode: Pt
Reference electrode: Standard hydrogen electrode (SHE)

When the potential of the electrode is scanned in the direction of about 700 mV to 100 mV with respect to the standard hydrogen electrode, 4H ⁺ + O ₂ + 4e ⁻ → 2H ₂ O between the working electrode and the Pt counter electrode
It can be seen that the oxygen reduction current due to. Measures the current value flowing at 400 mV (SHE standard) when scanned in the base direction, and converts the measured current value into a current value per unit weight (1 g) of the active component contained in the catalyst. Evaluated.

  In the following examples, since measurement cannot be performed if the catalyst activity is too large, for convenience of measurement, the electrode was prepared by diluting so that the ratio of the active component in the substrate-coated catalyst was reduced. The preferred active ingredient ratio for preparation and the preferred range of the active ingredient loading on the electrode are as described above.

[Comparative Example 1]
<Synthesis of RuTe _X (X = 4.77) catalyst>
Ru (acac) _{3, that} is, 0.7888 g of ruthenium acetylacetonate and 4.545 g of telluric acid (manufactured by Mitsuwa Chemical) were added to carbon black (VULCAN XC-72R (manufactured by Cabot) so that the charged molar ratio of Ru and Te was 1:10. , Specific surface area (BET) 254 m ^{2 /} g)) and 0.8 g physically mixed in a mortar to obtain a mixture. This mixture was heated from room temperature to 300 ° C. for 20 minutes and from 300 ° C. to 500 ° C. over 3 hours at a flow rate of 3 L / hr of hydrogen. Thereafter, it was kept at 500 ° C. for 2 hours and then cooled to room temperature. Finally, the catalyst was produced by leaving it in a nitrogen atmosphere containing 1% oxygen for 2 hours for passivation. This catalyst was analyzed by RuD ₂ (value of 2θ, 21.757 °, 26.202 °, 27.901 °, 31.294 °, 32.677 °, 33.897 °, 36.791 °, 39.858 °, 43.352 °, 44.444 °, 45.209 °, 45.900 ° by XRD analysis. , 48.304 °, 51.491 °, 53.912 °, 56.906 °, 59.005 °, 59.902 °, 68.508 °, 72.957 °, 78.340 °, 80.853 °, 82.115 °, 85.902 °) and Te (value of 2θ, 23.037) It was confirmed that it contained peaks at 27 °, 27.556 °, 38.261 °, 40.451 °, 49.609 °, 62.808 °, and 63.709 °).

<Creation of cathode electrode>
The obtained RuTe ₂ , Te and CB-containing catalyst and separately prepared carbon black (VULCAN XC-72R (manufactured by Cabot, specific surface area (BET) 254 m ² / g)) were mixed in a mortar. The total content of Ru and Te in this mixture was 0.01778% by weight. 28.27 mg of this mixture was mixed with 5 mL of ethanol, sufficiently stirred with an ultrasonic cleaner, and then the total amount of Ru and Te deposited with a microsyringe (calculated on the assumption that Ru and Te elements were not volatilized. And the same in the comparative example) was dropped onto a glassy carbon electrode as a working electrode so as to be 72.41 ng / cm ² and dried by standing. Next, a 5% Nafion (registered trademark) solution (alcohol solution, manufactured by Aldrich Chemical Co., Ltd.) was added dropwise, dried by standing, and then further dried under vacuum to obtain a cathode electrode.

CV measurement was performed on this cathode electrode, and the evaluation results of catalyst activity are shown in Table 2. Since it is unknown whether the active species is Ru ₁ Te _X or Ru itself having an interaction with Te, both the activity per unit weight of the total of Ru and Te and the activity per unit weight of Ru are determined. Described.

  The Te / Ru ratios of Examples 1, 7, 10 and Comparative Examples 1 and 2 were determined by inductively coupled plasma emission according to a conventional method by weighing the catalyst and decomposing it by melting with alkali, adding the acid and then adjusting the volume. Obtained by spectroscopic analysis.

  In the case of Examples 2 to 6, 8, 9 and Comparative Example 3, it is assumed that Ru and Te elements are volatilized and are not blown at the time of heating and heat treatment under hydrogen flow, and Ru and Te in the electrode are not blown. The total loading, Ru loading in the electrode, and catalytic activity were calculated.

[Example 1]
<Synthesis of RuTe _X (X = 2) catalyst>
The catalyst was prepared in the same manner as in Comparative Example 1, except that the amount of telluric acid (manufactured by Mitsuwa Chemical) in Comparative Example 1 was changed from 4.545 g to 1.818 g so that the charged molar ratio of Ru and Te was 1: 4. Was prepared. This compound was analyzed by XRD analysis using RuTe ₂ (value of 2θ, 21.788 °, 26.203 °, 27.902 °, 31.293 °, 32.694 °, 33.892 °, 39.850 °, 43.350 °, 44.412 °, 45.207 °, 45.842 °, 48.300 °, 51.459 °, 53.949 °, 56.906 °, 58.999 °, 59.814 °, 60.295 °, 68.500 °, 72.995 °, 73.543 °, 76.072 °, 78.303 °, 80.849 °, 82.402 °, 85.404 °, 85.901 °) It confirmed that it contained.

<Creation of cathode electrode>
Except for using the obtained catalyst, a cathode electrode was prepared by the same method as in Comparative Example 1 so that the total adhesion amount of Ru and Te was 32.15 ng / cm ^2. It was shown in 2.

[Example 2]
<Synthesis of RuTe _X (X = 2) catalyst using Ru chloride>
Instead of Ru (acac) ₃ , 0.7888 g and telluric acid (manufactured by Mitsuwa Chemical Co., Ltd.) 4.545 g in Comparative Example 1 so that the charged molar ratio of Ru and Te is 1: 2, ruthenium chloride (water-containing product, ruthenium content) They were dissolved in 50 ml of water using 0.476 g of 42% by weight (manufactured by NE Chemcat) and 0.909 g of telluric acid (manufactured by Mitsuwa Chemical). The carbon black (VULCAN XC-72) 0.8g was put in it so that it might become Ru / (Ru + CB) = 20 weight%, and it ultrasonicated at room temperature for 1 hour. Then, the solvent was distilled off with an evaporator, and the obtained residue was dried at 300 ° C. for 3 hours under an argon stream. Thereafter, the mixture was cooled to room temperature, and heated at a flow rate of 3 L / hr of hydrogen from room temperature to 300 ° C. for 20 minutes and from 300 ° C. to 800 ° C. over 3 hours. Thereafter, the mixture was kept at 800 ° C. for 2 hours and then cooled to room temperature. Finally, it was left to passivate in a nitrogen atmosphere containing 1% oxygen for 2 hours.

This compound was confirmed to contain RuTe ₂ by XRD analysis (values of 2θ were 21.991 °, 26.258 °, 28.044 °, 31.396 °, 32.757 °, 34.449 °, 39.996 °, 43.546 °, 45.441 °, 47.248 °, 48.448 °, 51.603 °, 53.703 °, 57.095 °, 60.344 °, 65.341 °, 66.506 °, 68.697 °, 73.156 °, 78.402 °, 81.098 °, 82.696 °, 86.052 °).

<Creation of cathode electrode>
Except for using the obtained RuTe ₂ -containing catalyst / CB, a cathode electrode was prepared by the same method as in Comparative Example 1 so that the total adhesion amount of Ru and Te was 19 ng / cm ^2, and evaluation was performed in the same manner. The results are shown in Table 2.

[Example 3]
<Synthesis of RuTe _X (X = 2) catalyst using nitric acid-based Ru>
Instead of Ru (acac) ₃ and 0.7888 g in Comparative Example 1, 5.37 g of telluric acid and 3.72% Ru (NO) (NO ₃ ) ₃ aqueous solution were used so that the charged molar ratio of Ru and Te was 1: 2. Using 0.909 g (manufactured by Mitsuwa Chemical), they were dissolved in 50 ml of water. The carbon black (VULCAN XC-72) 0.8g was put in it so that it might become Ru / (Ru + CB) = 20 weight%, and it ultrasonicated at room temperature for 1 hour. Then, the solvent was distilled off with an evaporator, and the obtained residue was dried at 300 ° C. for 3 hours under an argon stream. Thereafter, the mixture was cooled to room temperature, and heated at a flow rate of 3 L / hr of hydrogen from room temperature to 300 ° C. for 20 minutes and from 300 ° C. to 650 ° C. over 3 hours. Thereafter, it was kept at 650 ° C. for 2 hours, and then cooled to room temperature. Finally, it was left to passivate in a nitrogen atmosphere containing 1% oxygen for 2 hours.

This compound was confirmed to contain RuTe ₂ by XRD analysis (the values of 2θ were 21.755 °, 27.893 °, 31.250 °, 32.694 °, 34.342 °, 39.850 °, 43.351 °, 45.251 °, 47.108 °, 48.260 °, 51.499 °, 53.643 °, 56.949 °, 57.611 °, 65.204 °, 67.049 °, 68.804 °, 77.549 °, 80.907 °, 82.558 ° and 85.950 °).

<Creation of cathode electrode>
Except for using the obtained RuTe ₂ -containing catalyst / CB, a cathode electrode was prepared by the same method as in Comparative Example 1 so that the total adhesion amount of Ru and Te was 19 ng / cm ^2, and evaluation was performed in the same manner. The results are shown in Table 2.

[Example 4]
<Example in which the heat treatment temperature was 500 ° C. in Example 2>
A catalyst was synthesized in the same manner as in Example 2 except that the RuTe ₂ synthesis heat treatment temperature was 500 ° C.

That is, in place of Ru (acac) ₃ , 0.7888 g and telluric acid (manufactured by Mitsuwa Chemical Co., Ltd.) 4.545 g in Comparative Example 1 so that the charged molar ratio of Ru and Te is 1: 2, ruthenium chloride (water-containing product, They were dissolved in 50 ml of water using 0.476 g of ruthenium content of 42% by weight (manufactured by NE Chemcat) and 0.909 g of telluric acid (manufactured by Mitsuwa Chemical). The carbon black (VULCAN XC-72) 0.8g was put in it so that it might become Ru / (Ru + CB) = 20 weight%, and it ultrasonicated at room temperature for 1 hour. Then, the solvent was distilled off with an evaporator, and the obtained residue was dried at 300 ° C. for 3 hours under an argon stream. Thereafter, the mixture was cooled to room temperature, and heated at a flow rate of 3 L / hr of hydrogen from room temperature to 300 ° C. for 20 minutes and from 300 ° C. to 500 ° C. over 3 hours. Thereafter, it was kept at 500 ° C. for 2 hours and then cooled to room temperature. Finally, it was left to passivate in a nitrogen atmosphere containing 1% oxygen for 2 hours.

This compound was confirmed to contain RuTe ₂ by XRD analysis (the values of 2θ were 21.695 °, 27.855 °, 31.302 °, 32.741 °, 39.905 °, 43.448 °, 45.889 °, 48.300 °, 51.457 °, Peaks were given at 53.998 °, 57.199 °, 58.848 °, 65.247 °, 68.357 °, 73.096 °, 78.150 °, 82.486 °, 85.749 °, and 85.954 °).

<Creation of cathode electrode>
A cathode electrode was prepared in the same manner as in Comparative Example 1 except that the obtained RuTe ₂ -containing catalyst / CB was used so that the total adhesion amount of Ru and Te was 95 ng / cm ^2, and evaluation was performed in the same manner. The results are shown in Table 2.

[Example 5]
<Example in which the heat treatment temperature was 350 ° C. in Example 2>
A catalyst was synthesized in the same manner as in Example 2 except that the RuTe ₂ synthesis heat treatment temperature was 350 ° C.

That is, in place of Ru (acac) ₃ , 0.7888 g and telluric acid (manufactured by Mitsuwa Chemical Co., Ltd.) 4.545 g in Comparative Example 1 so that the charged molar ratio of Ru and Te is 1: 2, ruthenium chloride (water-containing product, They were dissolved in 50 ml of water using 0.476 g of ruthenium content of 42% by weight (manufactured by NE Chemcat) and 0.909 g of telluric acid (manufactured by Mitsuwa Chemical). The carbon black (VULCAN XC-72) 0.8g was put in it so that it might become Ru / (Ru + CB) = 20 weight%, and it ultrasonicated at room temperature for 1 hour. Then, the solvent was distilled off with an evaporator, and the obtained residue was dried at 300 ° C. for 3 hours under an argon stream. Thereafter, the mixture was cooled to room temperature, and heated at a flow rate of 3 L / hr of hydrogen from room temperature to 300 ° C. for 20 minutes and from 300 ° C. to 350 ° C. over 3 hours. Thereafter, it was kept at 350 ° C. for 2 hours and then cooled to room temperature. Finally, it was left to passivate in a nitrogen atmosphere containing 1% oxygen for 2 hours.

This compound was confirmed to contain RuTe ₂ by XRD analysis (2θ values peaked at 27.850 °, 28.155 °, 31.447 °, 32.449 °, 39.763 °, 43.700 °, 48.254 °, 57.108 °). )

<Creation of cathode electrode>
A cathode electrode was prepared by the same method as in Comparative Example 1 except that the obtained RuTe ₂ -containing catalyst / CB was used, so that the total adhesion amount of Ru and Te was 19 ng / cm ^2, and evaluation was performed in the same manner. The results are shown in Table 2.

[Example 6]
<Example in which the heat treatment temperature was 650 ° C. in Example 2>
<Synthesis of RuTe ₂ / carbon black (CB) catalyst>
A catalyst was synthesized in the same manner as in Example 2 except that the RuTe ₂ synthesis heat treatment temperature was 650 ° C.

That is, in place of Ru (acac) ₃ , 0.7888 g and telluric acid (manufactured by Mitsuwa Chemical Co., Ltd.) 4.545 g in Comparative Example 1 so that the charged molar ratio of Ru and Te is 1: 2, ruthenium chloride (water-containing product, They were dissolved in 50 ml of water using 0.476 g of ruthenium content of 42% by weight (manufactured by NE Chemcat) and 0.909 g of telluric acid (manufactured by Mitsuwa Chemical). The carbon black (VULCAN XC-72R) 0.8g was put in it so that it might become Ru / (Ru + CB) = 20 weight%, and it ultrasonicated at room temperature for 1 hour. Then, the solvent was distilled off with an evaporator, and the obtained residue was dried at 300 ° C. for 3 hours under an argon stream. Thereafter, the mixture was cooled to room temperature, and heated at a flow rate of 3 L / hr of hydrogen from room temperature to 300 ° C. for 20 minutes and from 300 ° C. to 650 ° C. over 3 hours. Thereafter, it was kept at 650 ° C. for 2 hours, and then cooled to room temperature. Finally, it was left to passivate in a nitrogen atmosphere containing 1% oxygen for 2 hours.

This compound was confirmed to contain RuTe ₂ by XRD analysis (values of 2θ were 21.899 °, 26.355 °, 27.951 °, 31.304 °, 32.753 °, 34.350 °, 39.949 °, 43.403 °, 45.300 °, 47.220 °, 48.307 °, 51.595 °, 53.702 °, 56.909 °, 59.946 °, 65.347 °, 68.598 °, 73.103 °, 78.302 °, 82.505 °, 85.996 °).

<Creation of cathode electrode>
A cathode electrode was prepared by the same method as in Comparative Example 1 except that the obtained RuTe ₂ -containing catalyst / CB was used, so that the total adhesion amount of Ru and Te was 19 ng / cm ^2, and evaluation was performed in the same manner. The results are shown in Table 2.
CV measurement was performed on this cathode electrode, and the evaluation results of catalyst activity are shown in Table 2.

[Example 7]
<Synthesis of RuTe _X (X = 2.11) catalyst>
Except that the amount of telluric acid (manufactured by Mitsuwa Chemical Co., Ltd.) in Comparative Example 1 was changed from 4.545 g to 0.909 g so that the charged molar ratio of Ru and Te was 1: 2, the same method as Comparative Example 1 was used. A catalyst was prepared. This compound was analyzed by XRD analysis using RuTe ₂ (value of 2θ, 21.507 °, 27.805 °, 31.300 °, 32.743 °, 40.041 °, 43.498 °, 45.356 °, 48.246 °, 51.441 °, 54.002 °, 57.057 °, 59.850 °, 65.306 °, 68.306 °, 73.347 °, 82.394 °, 85.753 °, and 86.095 °).

<Creation of cathode electrode>
Obtained are except that using the catalyst, Comparative Example 1. Table of results performed to create a cathode electrode such that the total amount of adhered Ru and Te is 19 ng / cm ^2, evaluated as the same manner as 2 It was shown to.

[ Comparative Example 4 ]
<Synthesis of RuTe _X (X = 1) catalyst>
The catalyst was prepared in the same manner as in Comparative Example 1 except that the amount of telluric acid (manufactured by Mitsuwa Chemical) in Comparative Example 1 was changed from 4.545 g to 0.4545 g so that the charged molar ratio of Ru and Te was 1: 1. Was prepared. This compound gave peaks at RuTe ₂ (values of 2θ, 21.901 °, 27.945 °, 31.300 °, 32.655 °, 40.047 °, 48.153 °, 51.594 °, 53.695 °, 65.170 °, 73.212 °, 82.447 ° by XRD analysis. And Ru (values of 2θ, which gave peaks at 38.449 °, 43.550 °, 57.199 °, 68.542 °, 78.451 °, and 85.997 °).

<Creation of cathode electrode>
Except for using the obtained catalyst, a cathode electrode was prepared by the same method as in Comparative Example 1 so that the total adhesion amount of Ru and Te was 12.02 ng / cm ^2. It was shown in 2.

[ Comparative Example 5 ]
<Synthesis of RuTe _X (X = 0.5) catalyst>
A catalyst was prepared in the same manner as in Comparative Example 4 except that the amount of telluric acid was changed to 0.227 g in Comparative Example 4 so that the charged molar ratio of Ru and Te was 1: 0.5. This compound was analyzed by XRD analysis with RuTe ₂ (value of 2θ, 21.846 °, 26.107 °, 27.907 °, 31.300 °, 32.745 °, 34.047 °, 39.897 °, 43.501 °, 45.244 °, 48.304 °, 51.590 °, 53.572 °, 54.003 °, 57.041 °, 68.555 °, 72.953 °, 82.364 °) and Ru (2θ, 38.705 °, 44.025 °, 78.394 °, 85.950 °) It was confirmed.

<Creation of cathode electrode>
Except for using the obtained RuTe ₂ -containing catalyst / CB, a cathode electrode was prepared by the same method as in Example 8 so that the total adhesion amount of Ru and Te was 12 ng / cm ^2, and evaluated in the same manner. The results are shown in Table 2.

[ Comparative Example 6 ]
<Synthesis of RuTe _X (X = 0.24) catalyst>
Except that the amount of telluric acid (manufactured by Mitsuwa Chemical) in Comparative Example 1 was changed from 4.545 g to 0.0909 g so that the charged molar ratio of Ru and Te was 1: 0.2, the same method as Comparative Example 1 The catalyst was prepared with This compound was analyzed by XRD analysis with RuTe ₂ (values at 2θ, peaks at 27.920 °, 31.298 °, and 32.512 °) and Ru (values at 2θ, 38.440 °, 42.205 °, 43.999 °, 69.351 °, 78.497 °, To give a peak at 84.630 °).

<Creation of cathode electrode>
A cathode electrode was prepared in the same manner as in Comparative Example 1 except that the obtained RuTe ₂ -containing catalyst / CB was used so that the total adhesion amount of Ru and Te was 6.66 ng / cm ^2. The results are shown in Table 2.

[Comparative Example 2]
<Synthesis of RuTe _X (X = 0.12) catalyst>
Except that the amount of telluric acid (manufactured by Mitsuwa Chemical Co., Ltd.) in Comparative Example 1 was changed from 4.545 g to 0.0250 g so that the charged molar ratio of Ru and Te was 1: 0.055, the same method as Comparative Example 1 The catalyst was prepared with

<Creation of cathode electrode>
Except for using the obtained catalyst, a cathode electrode was prepared by the same method as in Comparative Example 1 so that the total adhesion amount of Ru and Te was 5.68 ng / cm ^2. It was shown in 2.

[Comparative Example 3]
Add 0.299 g of Te metal (manufactured by NE Chemcat) and 0.5 g of Ru ₃ (CO) ₁₂ (manufactured by Aldrich) to 50 ml of m-Xylene and heat to reflux at 139 ° C. for 20 hours under N ₂ under reflux conditions. Then, a black powder was obtained by filtering the reaction solution. Next, the powder was washed with diethyl ether and air-dried to prepare a catalyst.

<Creation of cathode electrode>
Except for using the obtained catalyst, a cathode electrode was prepared by the same method as in Comparative Example 1 so that the total adhesion amount of Ru and Te was 5.75 ng / cm ^2. It was shown in 2.

  Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application (Japanese Patent Application No. 2005-183682) filed on June 23, 2005, and is incorporated by reference in its entirety.

Claims (18)

And tellurium (Te), comprising the <br/> ruthenium (Ru), when the composition expressed as _{Ru 1 Te X, 1 <X} < catalyst for a fuel cell, which is a 4. _{2. The} fuel cell catalyst according to claim 1, comprising RuTe2. According to claim 1, and tellurium (Te), in addition to ruthenium (Ru),
Rhodium (Rh), palladium (Pd), and at least one element L selected from the group consisting of osmium (Os), and iridium (Ir), when the composition expressed as L _Y Ru ₁ Te _X, 1 <X and 0 <Y ≦ 10. A fuel cell catalyst. 2. The fuel cell catalyst according to claim 1, further comprising a substrate on which Te and Ru are deposited. 5. The fuel cell catalyst according to claim 4, wherein the substrate is a carbon-based substrate.   2. The fuel cell catalyst according to claim 1, wherein the fuel cell is a polymer electrolyte fuel cell. An ion exchange membrane;
A fuel cell electrode material comprising the fuel cell catalyst layer of claim 1 formed on the ion exchange membrane.   A fuel cell electrode material comprising: an electrode gas diffusion layer; and a fuel cell catalyst layer according to claim 1 formed on the electrode gas diffusion layer.   A fuel cell electrode material comprising: a transfer film; and a fuel cell catalyst layer according to claim 1 formed on the transfer film.   A fuel cell electrode comprising the fuel cell catalyst according to claim 1. A fuel cell using the fuel cell electrode according to claim 10 . 12. The fuel cell according to claim 11, wherein the fuel cell is a polymer electrolyte fuel cell. A method for producing a fuel cell catalyst according to claim 5 ,
Mixing a carbon-based substrate, a precursor of Te and a precursor of Ru ;
A method for producing a catalyst for a fuel cell, comprising the step of activating the precursor. 6. A method for producing a fuel cell catalyst according to claim 5 , comprising a step of mixing a carbon-based substrate and the fuel cell catalyst according to claim 1. Method. 14. The method for producing a fuel cell catalyst according to claim 13 , further comprising a step of depositing a transition metal on the carbon-based substrate. 15. The method for producing a fuel cell catalyst according to claim 14 , further comprising a step of depositing a transition metal on the carbon-based substrate.   A fuel cell stack containing the fuel cell catalyst according to claim 1. A fuel cell system comprising the fuel cell stack according to claim 17 .