JP2012221929A - Method for manufacturing membrane electrode assembly, and method for manufacturing solid polymer fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for inexpensively manufacturing a membrane electrode assembly in which a catalyst non-formed region is accurately and simply formed in a catalyst layer and dispersibility of water can be improved, by producing an electrode catalyst for a fuel cell using titanium or the like and having high catalyst activity through heat treatment at relatively low temperature.SOLUTION: The method for manufacturing the membrane electrode assembly includes the steps of: preparing a catalyst precursor solution containing titanium or the like, removing a solvent, heat treating a solid residue and producing a catalyst (a); applying an anode catalyst paste and a cathode catalyst paste containing the catalyst (a) on first and second transfer films respectively; forming a laminate by overlapping the first and the second transfer films so as to sandwich a solid polymer electrolyte membrane so that each of the catalyst paste is directed to the solid polymer electrolyte membrane side; and hot-pressing the laminate by using a die having a hot-press surface in which a flat catalyst paste transfer section and a catalyst paste non-transfer section that has a predetermined depth with respect to the catalyst paste transfer section are formed.

Description

  The present invention relates to a polymer electrolyte fuel cell that generates electricity using an electrochemical reaction and a method for producing a membrane / electrode assembly applied thereto.

  A polymer electrolyte fuel cell is a type of fuel in which a solid polymer 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. It is a battery. Hydrogen or methanol is mainly used as the fuel.

  Conventionally, in order to increase the reaction speed of the fuel cell and increase the energy conversion efficiency of the fuel cell, a layer containing a catalyst (hereinafter referred to as “catalyst layer”) is provided on the cathode (air electrode) surface or anode (fuel electrode) surface of the fuel cell. It was also written).

FIG. 71 is a cross-sectional view illustrating the structure of a conventional polymer electrolyte fuel cell.
In FIG. 71, the membrane / electrode assembly 1 includes an anode catalyst layer 3 and a cathode catalyst layer 4 that are disposed with a solid polymer electrolyte membrane 2 interposed therebetween, and an anode side gas diffusion layer 5 and a cathode side gas diffusion layer 6 that are solid high. They are arranged on the anode catalyst layer 3 and the cathode catalyst layer 4 with the molecular electrolyte membrane 2 interposed therebetween, and are joined and integrated so as to be in close contact with each other. The membrane / electrode assembly 1 has a pair of separator plates 7 and 8 having gas flow paths 7a and 8a so that the gas flow paths 7a and 8a face the anode-side gas diffusion layer 5 and the cathode-side gas diffusion layer 6, respectively. It is arrange | positioned on both sides. The anode side gas diffusion layer 5 has a function of uniformly supplying fuel gas to the anode catalyst layer 3 and collecting current. The anode side gas diffusion layer 6 constitutes an anode electrode together with the anode catalyst layer 3, and the cathode side gas diffusion layer 6 is an oxidizing agent. A gas is supplied uniformly to the cathode catalyst layer 4 and has a function of collecting current. The cathode catalyst layer 4 and the cathode electrode constitute a cathode electrode.

  Here, for convenience of explanation, the polymer electrolyte fuel cell is shown as a single cell configured by sandwiching the membrane-electrode assembly 1 between separator plates 7, 8. A plurality of joined bodies 1 and separator plates 7 and 8 are alternately stacked.

  As described above, the conventional polymer electrolyte fuel cell is composed of a single catalyst layer in which the anode catalyst layer 3 and the cathode catalyst layer 4 are continuous. Therefore, since water moves to the cathode side as protons move, diffusion of water to the anode side hardly occurs. Moreover, the movement of water in the cathode catalyst layer 4 is less likely to occur. As a result, there is a problem that a local water excess state occurs in the cathode catalyst layer 4, the wet state in the solid polymer electrolyte membrane 2 becomes non-uniform, and the battery characteristics are deteriorated.

  In order to solve this problem, it is conceivable to provide fine grooves in the anode catalyst layer 3 and the cathode catalyst layer 4 to increase the efficiency of water diffusion. However, in the conventional manufacturing method, the catalyst layer having fine grooves is used. Could not be formed.

  In addition, since the anode catalyst layer 3 and the cathode catalyst layer 4 are each configured as a single continuous catalyst layer, there is a problem that sufficient cell characteristics cannot be obtained when the operating conditions of the fuel cell are changed.

  Therefore, in order to realize high battery performance under a wide range of operating conditions, it is considered effective to form a plurality of catalyst layers suitable for different operating conditions in the anode catalyst layer 3 and the cathode catalyst layer 4. In the method, a plurality of catalyst layers having different compositions cannot be accurately formed on the same plane.

  In Patent Document 1, in order to solve these problems, the first and second transfer films are sandwiched with the anode polymer paste and cathode catalyst paste facing the polymer electrolyte membrane side. And a laminate having a hot press surface on which a flat catalyst paste transfer portion and a catalyst paste non-transfer portion having a predetermined depth with respect to the catalyst paste transfer portion are formed. A manufacturing method of a membrane / electrode assembly in which the laminated body is hot-pressed is disclosed. According to this manufacturing method, a catalyst non-formation region can be accurately and easily formed in a catalyst layer, It is described that diffusibility can be improved.

  As the catalyst metal used in this catalyst paste, a metal having fine particles such as platinum supported on the surface of carbon black particles is used. However, since the price of platinum or the like is high, there is a problem that the manufacturing cost of the membrane / electrode assembly is high. Further, since the amount of resources such as platinum is limited, development of an alternative catalyst and a membrane / electrode assembly using the catalyst is required.

  In addition, the noble metal used for the cathode surface may be dissolved in an acidic atmosphere, and there is a problem that it is not suitable for applications that require long-term durability. Therefore, development of a catalyst that does not corrode in an acidic atmosphere, has excellent durability, and has a high oxygen reducing ability and a membrane / electrode assembly using the catalyst is strongly demanded.

  Base metal carbides, base metal oxides, base metal carbonitrides, chalcogen compounds, and carbon catalysts that do not use any precious metal have been reported as noble metal substitute catalysts (see, for example, Patent Documents 2 to 5). These materials are cheaper and have abundant resources than noble metal materials such as platinum.

However, these catalysts including the base metal materials described in Patent Document 2 and Patent Document 3 have a problem that a practically sufficient oxygen reducing ability is not obtained.
Moreover, although the catalyst described in patent document 4 and patent document 5 shows high oxygen reduction catalytic activity, it is a problem that stability under fuel cell operation conditions is very low.

As such a precious metal substitute catalyst, Nb and Ti oxycarbonitrides in Patent Document 6 and Patent Document 7 are attracting particular attention because they can effectively exhibit the above performance.
The catalysts described in Patent Document 6 and Patent Document 7 have extremely high performance compared to conventional noble metal alternative catalysts, but heat treatment at a high temperature of 1600 ° C. to 1800 ° C. is required in part of the production process. (For example, Patent Document 6 Example 1 or Patent Document 7 Example 1).

  Although such high-temperature heat treatment is not impossible industrially, it is difficult, and it leads to a rise in equipment costs and operation management difficulties. It was rare.

Patent Document 8 reports a technique relating to the production of carbon-containing titanium oxynitride containing carbon, nitrogen and oxygen.
However, in the production method described in Patent Document 8, in order to produce a carbon-containing titanium oxynitride, production of titanium oxynitride by reaction of a nitrogen-containing organic compound and a titanium precursor, and phenol resin and titanium oxynitride. A two-step synthesis of producing carbon-containing titanium oxynitride by reaction with a nitride precursor is required and the process is complicated. In particular, the production of the titanium oxynitride precursor requires a complicated process such as stirring at 80 ° C., heating, refluxing, cooling, and concentration under reduced pressure, and thus the production cost is high.

  Moreover, since the phenol resin is a thermosetting resin having a three-dimensional network structure, it is difficult to uniformly mix and react with the metal oxide. In particular, since the thermal decomposition temperature of the phenol resin is 400 ° C. to 900 ° C., there is a problem that a carbonization reaction due to complete decomposition of the phenol resin hardly occurs at a temperature of 1000 ° C. or less.

  Furthermore, Patent Document 8 and Non-Patent Document 1 merely describe the application as a thin film for a solar heat collector and a photocatalyst as its application, and the shape such as granular or fibrous shape that is highly useful as an electrode catalyst. The method for producing a metal oxycarbonitride and its use has not been disclosed or studied.

  Patent Document 9 discloses a method for producing an electrode catalyst characterized by firing a mixed material of an oxide and a carbon material precursor, but an electrode catalyst having sufficient catalytic performance has not been obtained. .

  Further, Patent Document 10 discloses a fuel cell electrode catalyst using a polynuclear complex such as cobalt. However, there is a problem in that the raw material has high toxicity, high cost, and insufficient catalytic activity. there were.

  Non-Patent Document 2 discloses a method for producing an electrode catalyst characterized by firing a mixed material of titanium alkoxide and a carbon material precursor, but in the production process, an organic substance containing nitrogen is used. No electrode catalyst having sufficient catalytic performance has been obtained.

JP 2004-39474 A JP 2004-303664 A International Publication No. 07/072665 Pamphlet US Patent Application Publication No. 2004/0096728 JP 2005-19332 A International Publication No. 2009/031383 Pamphlet International Publication No. 2009/107518 Pamphlet JP 2009-23887 A JP 2009-255053 A JP 2008-258150 A

Journal of Inorganic Materials (Chinese) 20, 4, P785 Electrochemistry Communications Volume 12, Issue 9, September 2010, Pages 1177-1179

An object of the present invention is to solve such problems in the prior art.
That is, an object of the present invention is platinum or the like having a high catalytic activity using a transition metal (such as titanium) through heat treatment at a relatively low temperature (that is, without providing a heat treatment (firing) step at high temperature). Produced a fuel cell electrode catalyst that can be used as an alternative catalyst, and a non-catalyst-forming region can be accurately and easily formed in the catalyst layer, improving the diffusibility of water at low cost. It is to provide a method of manufacturing.

The present invention relates to the following (1) to (6), for example.
(1)
(A) Step a1 in which at least a transition metal-containing compound, a nitrogen-containing organic compound, and a solvent are mixed to obtain a catalyst precursor solution,
A step a2 of removing the solvent from the catalyst precursor solution, and a step a3 of obtaining a fuel cell electrode catalyst (a) by heat-treating the solid residue obtained in the step a2 at a temperature of 500 to 1100 ° C.,
A catalyst production process in which a part or all of the transition metal-containing compound is a compound containing at least one transition metal element M1 selected from Group 4 and Group 5 elements of the periodic table as a transition metal element;
(B) applying an anode catalyst paste onto the first transfer film;
(C) preparing a cathode catalyst paste containing the fuel cell electrode catalyst (a) and applying it on the second transfer film;
(D) The first and second transfer films are stacked so that the anode catalyst paste and the cathode catalyst paste are directed toward the solid polymer electrolyte membrane so as to sandwich the solid polymer electrolyte membrane, thereby forming a laminate. Process,
(E) Hot pressing the laminate using a mold having a hot press surface on which a flat catalyst paste transfer portion and a catalyst paste non-transfer portion having a predetermined depth with respect to the catalyst paste transfer portion are formed, A method for producing a membrane / electrode assembly, comprising: a hot pressing step of transferring the anode catalyst paste and the cathode catalyst paste onto the solid polymer electrolyte membrane in substantially the same shape as the catalyst paste transfer portion.

(2)
The method for producing a membrane / electrode assembly according to (1), wherein the first and second transfer films are formed to a thickness of 10 μm or more and 50 μm or less.

(3)
In the hot pressing step (E), the plurality of molds formed so that the catalyst paste transfer portions do not overlap with each other are hot pressed one by one, and the anode catalyst paste and the cathode catalyst paste are The method for producing a membrane / electrode assembly according to the above (1), wherein the mold is transferred to the solid polymer electrolyte membrane in several times.

(4)
A membrane / electrode assembly is produced by the production method described in (1) above so that a non-catalyst forming region is formed in the anode catalyst layer and the cathode catalyst layer with the solid polymer electrolyte membrane interposed therebetween. And
An anode side gas diffusion layer and a cathode side gas diffusion layer are respectively disposed on the anode catalyst layer and the cathode catalyst layer to produce a membrane / electrode assembly with a gas diffusion layer,
A method for producing a polymer electrolyte fuel cell, comprising: laminating a plurality of membrane-electrode assemblies with a gas diffusion layer through a separator having a gas flow path formed therein.

(5)
The method for producing a polymer electrolyte fuel cell according to the above (4), wherein the anode catalyst layer and the cathode catalyst layer are composed of a plurality of catalyst forming regions separated by the catalyst non-forming region.

(6)
The above (5), wherein at least one of the anode catalyst layer and the cathode catalyst layer is formed of catalyst pastes having different compositions, and at least two types of the catalyst formation regions are mixed. ) A method for producing a polymer electrolyte fuel cell.

  According to the method for producing a membrane / electrode assembly of the present invention, a transition metal (such as titanium) is used after a heat treatment at a relatively low temperature (that is, without providing a heat treatment (firing) step at a high temperature). Produces an electrode catalyst for fuel cells that has a high catalytic activity and can be used as an alternative catalyst such as platinum. Using this catalyst, a non-catalyst formation area can be accurately and easily formed in the catalyst layer. Membrane / electrode assembly can be manufactured at low cost.

Moreover, according to the manufacturing method of said (2), the pattern of a fine catalyst non-formation area | region can be transcribe | transferred accurately.
Moreover, according to the manufacturing method of said (3), the catalyst layer of a different composition can be mixed.

FIG. 1 is a powder X-ray diffraction spectrum of the catalyst (1) of Catalyst Production Example 1-1. FIG. 2 is a powder X-ray diffraction spectrum of the catalyst (2) of Catalyst Production Example 1-2. FIG. 3 is a powder X-ray diffraction spectrum of the catalyst (3) of Catalyst Production Example 1-3. FIG. 4 is a powder X-ray diffraction spectrum of the catalyst (4) of Catalyst Production Example 1-4. FIG. 5 is a powder X-ray diffraction spectrum of catalyst (5) of Catalyst Production Example 1-5. FIG. 6 is a powder X-ray diffraction spectrum of catalyst (6) of Catalyst Production Example 1-6. FIG. 7 is a powder X-ray diffraction spectrum of the catalyst (7) of Catalyst Production Example 1-7. FIG. 8 is a powder X-ray diffraction spectrum of the catalyst (8) of Catalyst Production Example 8. FIG. 9 shows a current-potential curve obtained by evaluating the oxygen reducing ability of the fuel cell electrode (1) using the catalyst of Catalyst Production Example 2-1. FIG. 10 shows a current-potential curve in which the oxygen reducing ability of the fuel cell electrode (2) using the catalyst of Catalyst Production Example 2-2 was evaluated. FIG. 11 shows a current-potential curve in which the oxygen reducing ability of the fuel cell electrode (3) using the catalyst of Catalyst Production Example 2-3 was evaluated. FIG. 12 shows a current-potential curve in which the oxygen reducing ability of the fuel cell electrode (4) using the catalyst of Catalyst Production Example 2-4 was evaluated. FIG. 13: shows the electric current-potential curve which evaluated the oxygen reduction ability of the electrode (5) for fuel cells using the catalyst of catalyst manufacture example 2-5. FIG. 14 is a powder X-ray diffraction spectrum of the catalyst of Catalyst Production Example 3-1. FIG. 15 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reducing ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-1. FIG. 16 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-2 was evaluated. FIG. 17 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reducing ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-3. FIG. 18 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-4 was evaluated. FIG. 19 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-5 was evaluated. FIG. 20 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reducing ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-6. FIG. 21 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reducing ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-7. FIG. 22 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-8 was evaluated. FIG. 23 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-9 was evaluated. FIG. 24 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-11 was evaluated. FIG. 25 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-12 was evaluated. FIG. 26 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-13 was evaluated. FIG. 27 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-14 was evaluated. FIG. 28 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-15 was evaluated. FIG. 29 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-16 was evaluated. FIG. 30 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-17 was evaluated. FIG. 31 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-18 was evaluated. FIG. 32 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-19. FIG. 33 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-20 was evaluated. FIG. 34 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-21. FIG. 35 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-22. FIG. 36 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-23 was evaluated. FIG. 37 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-24 was evaluated. FIG. 38 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reducing ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-25. FIG. 39 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-26 was evaluated. FIG. 40 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-27 was evaluated. FIG. 41 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reducing ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-28. FIG. 42 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-29 was evaluated. FIG. 43 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-30 was evaluated. FIG. 44 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-31 was evaluated. FIG. 45 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-32 was evaluated. FIG. 46 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-33. FIG. 47 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-34 was evaluated. FIG. 48 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-36. FIG. 49 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-37. FIG. 50 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of the fuel cell electrode using the catalyst of Catalyst Production Example 3-38 was evaluated. FIG. 51 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-39 was evaluated. FIG. 52 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-40 was evaluated. FIG. 53 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-41 was evaluated. FIG. 54 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reduction ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-42. FIG. 55 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reducing ability of a fuel cell electrode using the catalyst of Catalyst Production Example 3-43. FIG. 56 shows an oxygen reduction current density-potential curve obtained by evaluating the oxygen reducing ability of the fuel cell electrode using the catalyst of Comparative Catalyst Production Example 3-1. FIG. 57 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Comparative Catalyst Production Example 3-2 was evaluated. FIG. 58 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Comparative Catalyst Production Example 3-3 was evaluated. FIG. 59 shows an oxygen reduction current density-potential curve in which the oxygen reduction ability of a fuel cell electrode using the catalyst of Comparative Catalyst Production Example 3-4 was evaluated. FIG. 60 shows an oxygen reduction current density-potential curve in which the oxygen reducing ability of a fuel cell electrode using the catalyst of Comparative Catalyst Production Example 3-5 was evaluated. It is sectional drawing explaining the structure of the polymer electrolyte fuel cell which concerns on Embodiment 1 of this invention. It is a principal part plane part explaining the formation state of the anode catalyst layer in the polymer electrolyte fuel cell which concerns on Embodiment 1 of this invention. It is a top view which shows the hot press surface of the metal mold | die applied to the manufacturing method of the membrane electrode assembly of the polymer electrolyte fuel cell which concerns on Embodiment 1 of this invention. It is a side view explaining the manufacturing method of the membrane electrode assembly of the polymer electrolyte fuel cell which concerns on Embodiment 1 of this invention. It is a principal part plane part explaining the formation state of the cathode catalyst layer in the polymer electrolyte fuel cell which concerns on Embodiment 2 of this invention. It is a top view which shows the hot press surface of the 1st metal mold | die applied to the manufacturing method of the membrane electrode assembly of the polymer electrolyte fuel cell which concerns on Embodiment 2 of this invention. It is a top view which shows the hot press surface of the 2nd metal mold | die applied to the manufacturing method of the membrane electrode assembly of the polymer electrolyte fuel cell which concerns on Embodiment 2 of this invention. It is a side view explaining the 1st hot press process in the manufacturing method of the membrane electrode assembly of the polymer electrolyte fuel cell which concerns on Embodiment 2 of this invention. It is a principal part plane part explaining the formation state of the cathode catalyst layer by the 1st hot press process in the manufacturing method of the membrane electrode assembly of the polymer electrolyte fuel cell which concerns on Embodiment 2 of this invention. It is a side view explaining the 2nd hot press process in the manufacturing method of the membrane electrode assembly of the polymer electrolyte fuel cell which concerns on Embodiment 2 of this invention. It is sectional drawing explaining the structure of the conventional polymer electrolyte fuel cell.

Hereinafter, the present invention will be described in more detail.
[Electrocatalyst for fuel cell (a)]
First, the manufacturing method of the electrode catalyst (a) for fuel cells used by this invention is demonstrated.

The catalyst production step (A)
Step a1, wherein at least a transition metal-containing compound, a nitrogen-containing organic compound and a solvent are mixed to obtain a solution (also referred to herein as “catalyst precursor solution”),
A step a2 of removing the solvent from the catalyst precursor solution, and a step a3 of obtaining a fuel cell electrode catalyst (a) by heat-treating the solid residue obtained in the step a2 at a temperature of 500 to 1100 ° C.,
Part or all of the transition metal-containing compound is a compound containing at least one transition metal element M1 selected from Group 4 and Group 5 elements of the periodic table as a transition metal element. In the present specification, unless otherwise specified, atoms and ions are described as “atoms” without strictly distinguishing them.

(Step a1)
In step a1, at least a transition metal-containing compound, a nitrogen-containing organic compound, and a solvent are mixed to obtain a catalyst precursor solution.

As the mixing procedure, for example,
Step (i): Prepare a solvent in one container, add the transition metal-containing compound and the nitrogen-containing organic compound thereto, dissolve them, and mix them.
Step (ii): preparing a solution of the transition metal-containing compound and a solution of the nitrogen-containing organic compound and mixing them.

  When the solvent having high solubility for each component is different, the procedure (ii) is preferable. Further, when the transition metal-containing compound is, for example, a metal halide described later, the procedure (i) is preferable, and when the transition metal-containing compound is, for example, a metal alkoxide or a metal complex described later, a procedure is performed. (Ii) is preferred.

As a preferable procedure in the procedure (ii) in the case of using the first transition metal-containing compound and the second transition metal-containing compound described later as the transition metal-containing compound,
Step (ii ′): preparing a solution of the first transition metal-containing compound and a solution of the second transition metal-containing compound and the nitrogen-containing organic compound and mixing them.

The mixing operation is preferably performed with stirring in order to increase the dissolution rate of each component in the solvent.
When mixing the solution of the transition metal-containing compound and the solution of the nitrogen-containing organic compound, it is preferable to supply the other solution to one solution at a constant rate using a pump or the like.

It is also preferable to add the transition metal-containing compound solution to the nitrogen-containing organic compound solution little by little (that is, not to add the whole amount at once).
The catalyst precursor solution is considered to contain a reaction product of a transition metal-containing compound and a nitrogen-containing organic compound. The solubility of the reaction product in the solvent varies depending on the combination of the transition metal-containing compound, the nitrogen-containing organic compound, the solvent, and the like.

  Therefore, for example, when the transition metal-containing compound is a metal alkoxide or a metal complex, the catalyst precursor solution preferably contains a precipitate or a dispersoid, although it depends on the type of solvent and the type of nitrogen-containing organic compound. Even if included, these are a small amount (for example, 10% by weight or less, preferably 5% by weight or less, more preferably 1% by weight or less of the total amount of the solution). Further, the catalyst precursor solution is preferably clear, and for example, a value measured by a liquid transparency measurement method described in JIS K0102 is preferably 1 cm or more, more preferably 2 cm or more, and still more preferably 5 cm or more.

  On the other hand, for example, when the transition metal-containing compound is a metal halide, the catalyst precursor solution contains a transition metal-containing compound and a nitrogen-containing organic compound, depending on the type of solvent and the type of nitrogen-containing organic compound. The precipitate considered to be the reaction product of

In step a1, a transition metal-containing compound, a nitrogen-containing organic compound, and a solvent are placed in a pressurizable container such as an autoclave, and mixing may be performed while applying a pressure equal to or higher than normal pressure.
The temperature at the time of mixing a transition metal containing compound, a nitrogen containing organic compound, and a solvent is 0-60 degreeC, for example. Assuming that a complex is formed from the transition metal-containing compound and the nitrogen-containing organic compound, when this temperature is excessively high, the complex is hydrolyzed when the solvent contains water, resulting in the precipitation of hydroxide. It is considered that an excellent catalyst cannot be obtained. If this temperature is excessively low, the transition metal-containing compound is precipitated before the complex is formed, and it is considered that an excellent catalyst cannot be obtained.

<Transition metal-containing compound>
Part or all of the transition metal-containing compound is a compound containing at least one transition metal element M1 selected from Group 4 and Group 5 elements of the periodic table as a transition metal element. Specific examples of the transition metal element M1 include titanium, zirconium, hafnium, vanadium, niobium, and tantalum. These may be used alone or in combination of two or more.

  Among the transition metal elements M1, titanium, zirconium, niobium and tantalum are preferable, and titanium and zirconium are more preferable from the viewpoint of cost and performance of the obtained catalyst.

  The transition metal-containing compound preferably has at least one selected from an oxygen atom and a halogen atom, and specific examples thereof include a metal phosphate, a metal sulfate, a metal nitrate, a metal organic acid salt, Examples thereof include metal acid halides (intermediate hydrolysates of metal halides), metal alkoxides, metal halides, metal halides and metal hypohalites, and metal complexes. These may be used alone or in combination of two or more.

  As the metal alkoxide, methoxide, propoxide, isopropoxide, ethoxide, butoxide and isobutoxide of the transition metal are preferable, and isopropoxide, ethoxide and butoxide of the transition metal are more preferable. The metal alkoxide may have one type of alkoxy group or may have two or more types of alkoxy groups.

  As the transition metal-containing compound having an oxygen atom, an alkoxide, an acetylacetone complex, an acid chloride, and a sulfate are preferable, and from the viewpoint of cost, an alkoxide and an acetylacetone complex are more preferable, and a viewpoint of solubility in a solvent in the liquid phase Therefore, an alkoxide and an acetylacetone complex are more preferable.

  The metal halide is preferably a chloride, bromide or iodide of the transition metal, and the metal acid halide is preferably an acid chloride, acid bromide or acid iodide of the transition metal.

The metal perhalogenate is preferably a metal perchlorate, and the metal hypohalite is preferably a metal hypochlorite.
Specific examples of the transition metal-containing compound include
Titanium tetramethoxide, titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, titanium tetraisobutoxide, titanium tetrapentoxide, titanium tetraacetylacetonate, titaniumoxydiacetylacetonate, tris (acetyl Acetonato) titanium chloride ([Ti (acac) ₃ ] ₂ [TiCl ₆ ]), titanium tetrachloride, titanium trichloride, titanium oxychloride, titanium tetrabromide, titanium tribromide, titanium oxybromide, Titanium compounds such as titanium tetraiodide, titanium triiodide, and titanium oxyiodide;
Niobium pentamethoxide, niobium pentaethoxide, niobium pentaisopropoxide, niobium pentaboxide, niobium pentapentoxide, niobium pentachloride, niobium oxychloride, niobium pentabromide, niobium oxybromide, niobium pentaiodide, niobium pentaiodide, oxyiodination Niobium compounds such as niobium;
Zirconium tetramethoxide, zirconium tetraethoxide, zirconium tetrapropoxide, zirconium tetraisopropoxide, zirconium tetrabutoxide, zirconium tetraisobutoxide, zirconium tetrapentoxide, zirconium tetraacetylacetonate, zirconium tetrachloride, zirconium oxychloride, four Zirconium compounds such as zirconium bromide, zirconium oxybromide, zirconium tetraiodide, zirconium oxyiodide;
Tantalum pentamethoxide, tantalum pentaethoxide, tantalum pentaisopropoxide, tantalum pentabutoxide, tantalum pentapentoxide, tantalum tetraethoxyacetylacetonate, tantalum pentachloride, tantalum oxychloride, tantalum pentabromide, tantalum oxybromide, Tantalum compounds such as tantalum pentaiodide and tantalum oxyiodide;
Hafnium tetramethoxide, hafnium tetraethoxide, hafnium tetrapropoxide, hafnium tetraisopropoxide, hafnium tetrabutoxide, hafnium tetraisobutoxide, hafnium tetrapentoxide, hafnium tetraacetylacetonate, hafnium tetrachloride, hafnium oxychloride, odor Hafnium compounds such as hafnium iodide, hafnium oxybromide, hafnium iodide, hafnium oxyiodide;
Vanadium oxytrimethoxide, vanadium oxytriethoxide, vanadium oxytriisopropoxide, vanadium oxytributoxide, vanadium (III) acetylacetonate, vanadium (IV) acetylacetonate, vanadium pentachloride, vanadium oxychloride, five odors And vanadium compounds such as vanadium iodide, vanadium oxybromide, vanadium pentaiodide, and vanadium oxyiodide. These may be used alone or in combination of two or more.

Among these compounds, the resulting catalyst becomes fine particles with a uniform particle size, and its activity is high,
Titanium tetraethoxide, titanium tetrachloride, titanium oxychloride, titanium tetraisopropoxide, titanium tetraacetylacetonate,
Niobium pentaethoxide, niobium pentachloride, niobium oxychloride, niobium pentaisopropoxide,
Zirconium tetraethoxide, zirconium tetrachloride, zirconium oxychloride, zirconium tetraisopropoxide, zirconium tetraacetylacetonate,
Tantalum pentamethoxide, tantalum pentaethoxide, tantalum pentachloride, tantalum oxychloride, tantalum pentaisopropoxide, and tantalum tetraethoxyacetylacetonate are preferred, titanium tetraisopropoxide, titanium tetraacetylacetonate, niobium ethoxide, More preferred are niobium isopropoxide, zirconium oxychloride, zirconium tetraisopropoxide, and tantalum pentaisopropoxide.

  In addition, as the transition metal-containing compound, together with a transition metal-containing compound containing a transition metal element M1 of Group 4 or Group 5 of the periodic table as a transition metal element (hereinafter also referred to as “first transition metal-containing compound”), As the transition metal element, a transition metal-containing compound (hereinafter referred to as “second metal”) which is an element different from the transition metal element M1 and includes at least one transition metal element M2 selected from iron, nickel, chromium, cobalt, vanadium and manganese. May also be used in combination. Use of the second transition metal-containing compound improves the performance of the resulting catalyst.

  From the observation of the XPS spectrum of the catalyst, when the second transition metal-containing compound is used, bond formation between the transition metal element M1 (for example, titanium) and a nitrogen atom is promoted, and as a result, the performance of the catalyst is not improved. I guess that.

As the transition metal element M2 in the second transition metal-containing compound, iron and chromium are preferable and iron is more preferable from the viewpoint of a balance between cost and performance of the obtained catalyst.
As a specific example of the second transition metal-containing compound,
Iron (II) chloride, iron (III) chloride, iron (III) sulfate, iron (II) sulfide, iron (III) sulfide, potassium ferrocyanide, potassium ferricyanide, ammonium ferrocyanide, ammonium ferricyanide, iron ferrocyanide , Iron (II) nitrate, iron (III) nitrate, iron (II) oxalate, iron (III) oxalate, iron (II) phosphate, iron (III) phosphate ferrocene, iron (II) hydroxide, water Iron compounds such as iron (III) oxide, iron (II) oxide, iron (III) oxide, triiron tetroxide, iron (II) acetate, iron (II) lactate, iron (III) citrate;
Nickel chloride (II), nickel sulfate (II), nickel sulfide (II), nickel nitrate (II), nickel oxalate (II), nickel phosphate (II), nickel cene, nickel hydroxide (II), nickel oxide Nickel compounds such as (II), nickel acetate (II), nickel lactate (II);
Chromium (II) chloride, chromium (III) chloride, chromium (III) sulfate, chromium (III) sulfide, chromium (III) nitrate, chromium (III) oxalate, chromium (III) phosphate, chromium (III) hydroxide Chromium compounds such as, chromium (II) oxide, chromium (III) oxide, chromium (IV) oxide, chromium (VI) oxide, chromium (II) acetate, chromium (III) acetate, chromium (III) lactate;
Cobalt (II) chloride, cobalt (III) chloride, cobalt (II) sulfate, cobalt (II) sulfide, cobalt (II) nitrate, cobalt (III) nitrate, cobalt (II) oxalate, cobalt (II) phosphate, Cobalt compounds such as cobaltocene, cobalt (II) hydroxide, cobalt (II) oxide, cobalt (III) oxide, tricobalt tetroxide, cobalt (II) acetate, and cobalt (II) lactate;
Vanadium chloride (II), vanadium chloride (III), vanadium chloride (IV), vanadium oxysulfate (IV), vanadium sulfide (III), vanadium oxyoxalate (IV), vanadium metallocene, vanadium oxide (V), vanadium acetate Vanadium compounds such as vanadium citrate;
Manganese chloride (II), manganese sulfate (II), manganese sulfide (II), manganese nitrate (II), manganese oxalate (II), manganese hydroxide (II), manganese oxide (II), manganese oxide (III), Examples thereof include manganese compounds such as manganese acetate (II), manganese lactate (II), and manganese citrate. These may be used alone or in combination of two or more.

Among these compounds,
Iron (II) chloride, iron (III) chloride, potassium ferrocyanide, potassium ferricyanide, ammonium ferrocyanide, ammonium ferricyanide, iron (II) acetate, iron (II) lactate,
Nickel (II) chloride, nickel (II) acetate, nickel (II) lactate,
Chromium (II) chloride, chromium (III) chloride, chromium (II) acetate, chromium (III) acetate, chromium (III) lactate,
Cobalt (II) chloride, cobalt (III) chloride, cobalt (II) acetate, cobalt (II) lactate,
Vanadium chloride (II), vanadium chloride (III), vanadium chloride (IV), vanadium oxysulfate (IV), vanadium acetate, vanadium citrate,
Manganese chloride (II), manganese acetate (II) and manganese lactate (II) are preferred,
Iron (II) chloride, iron (III) chloride, potassium ferrocyanide, potassium ferricyanide, ammonium ferrocyanide, ammonium ferricyanide, iron (II) acetate, iron (II) lactate, chromium (II) chloride, chromium chloride (III ), Chromium (II) acetate, chromium (III) acetate, and chromium (III) lactate.

<Nitrogen-containing organic compound>
The nitrogen-containing organic compound is preferably a compound (preferably a compound capable of forming a mononuclear complex) that can be a ligand capable of coordinating to a metal atom in the transition metal-containing compound. More preferred are compounds that can be (preferably bidentate or tridentate) (can form chelates).

The said nitrogen containing organic compound may be used individually by 1 type, and may use 2 or more types together.
The nitrogen-containing organic compound is preferably an amino group, a nitrile group, an imide group, an imine group, a nitro group, an amide group, an azido group, an aziridine group, an azo group, an isocyanate group, an isothiocyanate group, an oxime group, a diazo group, It has a functional group such as a nitroso group, or a ring such as a pyrrole ring, a porphyrin ring, an imidazole ring, a pyridine ring, a pyrimidine ring, or a pyrazine ring (these functional groups and rings are also collectively referred to as “nitrogen-containing molecular groups”). .

  When the nitrogen-containing organic compound has a nitrogen-containing molecular group in the molecule, it is considered that the nitrogen-containing organic compound can be coordinated more strongly with the transition metal atom derived from the transition metal-containing compound through mixing in step a1.

  Among the nitrogen-containing molecular groups, an amino group, an imine group, an amide group, a pyrrole ring, a pyridine ring and a pyrazine ring are more preferable, an amino group, an imine group, a pyrrole ring and a pyrazine ring are more preferable, and an amino group and a pyrazine ring are preferable. Is particularly preferred because the activity of the resulting catalyst is particularly high.

  Specific examples of the nitrogen-containing organic compound (which does not include an oxygen atom) include melamine, ethylenediamine, ethylenediamine dihydrochloride, triazole, acetonitrile, acrylonitrile, ethyleneimine, aniline, pyrrole, polyethyleneimine, and the like. Of these, ethylenediamine and ethylenediamine dihydrochloride are preferred because of the high activity of the resulting catalyst.

  The nitrogen-containing organic compound is preferably a hydroxyl group, a carboxyl group, an aldehyde group, an acid halide group, a sulfo group, a phosphoric acid group, a ketone group, an ether group or an ester group (these are collectively referred to as “oxygen-containing molecular group”). .) If the nitrogen-containing organic compound has an oxygen-containing molecular group in the molecule, it is considered that the nitrogen-containing organic compound can be coordinated more strongly with the transition metal atom derived from the transition metal-containing compound through the mixing in step a1.

Among the oxygen-containing molecular groups, a carboxyl group and an aldehyde group are particularly preferable because the activity of the resulting catalyst is particularly high.
As the nitrogen-containing organic compound containing an oxygen atom in the molecule, the nitrogen-containing molecular group and the compound having the oxygen-containing molecular group are preferable. Such a compound is considered to be capable of particularly strongly coordinating to the transition metal atom derived from the transition metal-containing compound via the step a1.

As the compound having the nitrogen-containing molecular group and the oxygen-containing molecular group, amino acids having an amino group and a carboxyl group, and derivatives thereof are preferable.
Examples of the amino acids include alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, serine, threonine, tryptophan, tyrosine, valine, norvaline, glycylglycine, Triglycine and tetraglycine are preferred, and the activity of the resulting catalyst is high. Alanine, glycine, lysine, methionine, and tyrosine are more preferred, and the resulting catalyst exhibits extremely high activity, so that alanine, glycine, and lysine are particularly preferred. preferable.

  Specific examples of the nitrogen-containing organic compound containing an oxygen atom in the molecule include acylpyrroles such as acetylpyrrole, acylimidazoles such as pyrrolecarboxylic acid and acetylimidazole, carbonyldiimidazole and imidazole Carboxylic acid, pyrazole, acetanilide, pyrazinecarboxylic acid, piperidinecarboxylic acid, piperazinecarboxylic acid, morpholine, pyrimidinecarboxylic acid, nicotinic acid, 2-pyridinecarboxylic acid, 2,4-pyridinedicarboxylic acid, 8-quinolinol, and polyvinylpyrrolidone Compounds that can be bidentate ligands, specifically pyrrole-2-carboxylic acid, imidazole-4-carboxylic acid, 2-pyrazinecarboxylic acid, 2-piperidinecarboxylic acid , 2-piperazine carboxylic acid, nicotinic acid, 2-pyridinecarboxylic acid, 2,4-pyridinedicarboxylic acid, and 8-quinolinol are preferable, and 2- pyrazine carboxylic acid, and 2-pyridine carboxylic acid is more preferable.

  The ratio (B / A) of the total number of carbon atoms B of the nitrogen-containing organic compound used in step a1 to the total number A of transition metal elements of the transition metal-containing compound used in step a1 is determined in step a3. It is possible to reduce components desorbed as carbon compounds such as carbon dioxide and carbon monoxide during the heat treatment, that is, since it is possible to reduce the amount of exhaust gas during catalyst production, it is preferably 200 or less, more preferably 150 or less, more preferably 80 or less, particularly preferably 30 or less. From the viewpoint of obtaining a catalyst having a good activity, it is preferably 1 or more, more preferably 2 or more, further preferably 3 or more, particularly preferably 5 or more. It is.

  The ratio (C / A) of the total atom number C of nitrogen of the nitrogen-containing organic compound used in step a1 to the total atom number A of the transition metal element of the transition metal-containing compound used in step a1 is good activity. From the standpoint of obtaining a catalyst having a good activity, it is preferably 28 or less, more preferably 17 or less, still more preferably 12 or less, particularly preferably 8.5 or less. , More preferably 2.5 or more, further preferably 3 or more, particularly preferably 3.5 or more.

  The ratio of the first transition metal-containing compound and the second transition metal-containing compound used in step a1 is set to a molar ratio (M1: M2) between the atoms of the transition metal element M1 and the atoms of the transition metal element M2. In terms of M1: M2 = (1-a): a, the range of a is preferably 0.01 ≦ a ≦ 0.5, more preferably 0.02 ≦ a ≦ 0.4, especially Preferably it is 0.05 <= a <= 0.3.

<Solvent>
Examples of the solvent include water, alcohols and acids. As alcohols, ethanol, methanol, butanol, propanol and ethoxyethanol are preferable, and ethanol and methanol are more preferable. As the acids, acetic acid, nitric acid (aqueous solution), hydrochloric acid, phosphoric acid aqueous solution and citric acid aqueous solution are preferable, and acetic acid and nitric acid are more preferable. These may be used alone or in combination of two or more.

As the solvent when the transition metal-containing compound is a metal halide, methanol is preferable.
<Precipitation inhibitor>
When the transition metal-containing compound contains a halogen atom such as titanium chloride, niobium chloride, zirconium chloride, or tantalum chloride, these compounds are generally easily hydrolyzed by water to produce hydroxides or acid chlorides. It tends to cause precipitation of things. Therefore, when the transition metal-containing compound contains a halogen atom, it is preferable to add 1% by weight or more of a strong acid. For example, if the acid is hydrochloric acid, the addition of the acid so that the concentration of hydrogen chloride in the solution is 5% by weight or more, more preferably 10% by weight or more, suppresses the occurrence of precipitation derived from the transition metal-containing compound. However, a clear catalyst precursor solution can be obtained.

  Also when the transition metal-containing compound is a metal complex and water is used alone or water and another compound are used as the solvent, it is preferable to use a precipitation inhibitor. In this case, the precipitation inhibitor is preferably a compound having a diketone structure, more preferably diacetyl, acetylacetone, 2,5-hexanedione and dimedone, and further preferably acetylacetone and 2,5-hexanedione.

  These precipitation inhibitors are preferably 1 to 70% by weight, more preferably 2% in 100% by weight of a transition metal-containing compound solution (a solution containing the transition metal-containing compound and not containing the nitrogen-containing organic compound). It is added in an amount of -50% by weight, more preferably 15-40% by weight.

  These precipitation inhibitors are preferably used in an amount of 0.1 to 40% by weight, more preferably 0.5 to 20% by weight, and further preferably 2 to 10% by weight in 100% by weight of the catalyst precursor solution. Added.

The precipitation inhibitor may be added at any stage in step a1.
In step a1, preferably, a solution containing the transition metal-containing compound and the precipitation inhibitor is prepared, and then this solution and the nitrogen-containing organic compound are mixed to obtain a catalyst precursor solution. In addition, in the case where the first transition metal-containing compound and the second transition metal-containing compound are used as the transition metal-containing compound, in step a1, preferably, the first transition metal-containing compound and the precipitation are used. A solution containing an inhibitor is prepared, and then this solution is mixed with the nitrogen-containing organic compound and the second transition metal-containing compound to obtain a catalyst precursor solution. When the step a1 is performed in this way, the occurrence of the precipitation can be suppressed more reliably.

(Step a2)
In step a2, the solvent is removed from the catalyst precursor solution obtained in step a1.
The removal of the solvent may be performed in the air or in an inert gas (for example, nitrogen, argon, helium) atmosphere. As the inert gas, nitrogen and argon are preferable from the viewpoint of cost, and nitrogen is more preferable.

  The temperature at the time of solvent removal may be room temperature when the vapor pressure of the solvent is high, but from the viewpoint of mass production of the catalyst, it is preferably 30 ° C or higher, more preferably 40 ° C or higher, and still more preferably. From the viewpoint of not decomposing the catalyst precursor that is estimated to be a metal complex such as a chelate, which is contained in the solution obtained in step a1 at 50 ° C or higher, preferably 250 ° C or lower, more preferably 150 ° C. Below, it is 110 degrees C or less more preferably.

  The removal of the solvent may be performed under atmospheric pressure when the vapor pressure of the solvent is high, but in order to remove the solvent in a shorter time, it is performed under reduced pressure (for example, 0.1 Pa to 0.1 MPa). Also good. For example, an evaporator can be used to remove the solvent under reduced pressure.

The solvent may be removed while the mixture obtained in step a1 is allowed to stand, but in order to obtain a more uniform solid residue, it is preferable to remove the solvent while rotating the mixture.
When the weight of the container containing the mixture is large, it is preferable to rotate the solution using a stirring rod, a stirring blade, a stirring bar, or the like.

  In addition, when removing the solvent while adjusting the degree of vacuum of the container containing the mixture, since it will be dried in a container that can be sealed, removing the solvent while rotating the entire container, For example, it is preferable to remove the solvent using a rotary evaporator.

  Depending on the method of removing the solvent or the properties of the transition metal-containing compound or the nitrogen-containing organic compound, the composition or aggregated state of the solid residue obtained in step a2 may be non-uniform. In such a case, a catalyst having a more uniform particle size can be obtained by mixing and crushing the solid residue and using a more uniform and fine powder in step a3.

  For mixing and crushing solid residue, for example, roll rolling mill, ball mill, small diameter ball mill (bead mill), medium stirring mill, airflow crusher, mortar, automatic kneading mortar, tank crusher, jet mill If the solid residue is small, preferably, a mortar, an automatic kneading mortar, or a batch type ball mill is used, and when the solid residue is large and continuous mixing and crushing are performed. A jet mill is preferably used.

(Step a3)
In step a3, the solid content residue obtained in step a2 is heat-treated to obtain a fuel cell electrode catalyst (a).

The temperature at the time of this heat treatment is 500 to 1100 ° C, preferably 600 to 1050 ° C, more preferably 700 to 950 ° C.
If the temperature of the heat treatment is too higher than the above range, sintering and grain growth occur between the particles of the obtained electrode catalyst, resulting in a decrease in the specific surface area of the electrode catalyst. As a result, the processability during processing into a catalyst layer is poor. On the other hand, if the temperature of the heat treatment is too lower than the above range, an electrode catalyst having high activity cannot be obtained.

Examples of the heat treatment method include a stationary method, a stirring method, a dropping method, and a powder trapping method.
The stationary method is a method in which the solid residue obtained in step a2 is placed in a stationary electric furnace or the like and heated. The solid content residue weighed during heating may be put in a ceramic container such as an alumina board or a quartz board. The stationary method is preferable in that a large amount of the solid residue can be heated.

  The stirring method is a method in which the solid residue is placed in an electric furnace such as a rotary kiln and heated while stirring. The stirring method is preferable in that a large amount of the solid residue can be heated and aggregation and growth of the obtained electrode catalyst particles can be suppressed. Furthermore, the stirring method is preferable in that the electrode catalyst can be continuously produced by inclining the heating furnace.

  In the dropping method, an atmospheric gas is passed through an induction furnace, the furnace is heated to a predetermined heating temperature, and after maintaining a thermal equilibrium at the temperature, the solid residue is placed in a crucible that is a heating area of the furnace. It is a method of dropping and heating this. The dropping method is preferred in that aggregation and growth of the obtained electrocatalyst particles can be minimized.

  Powder capture method is an inert gas atmosphere containing a small amount of oxygen gas, the solid residue is splashed and suspended, captured in a vertical tube furnace maintained at a predetermined heating temperature, It is a method of heating.

  When the heat treatment is performed by the stationary method, the rate of temperature rise is not particularly limited, but is preferably about 1 ° C / min to 100 ° C / min, and more preferably 5 ° C / min to 50 ° C / min. is there. The heating time is preferably 0.1 to 10 hours, more preferably 0.5 hours to 5 hours, and further preferably 0.5 to 3 hours. When heating is performed in a tubular furnace in the stationary method, the heating time of the electrode catalyst particles is 0.1 to 10 hours, preferably 0.5 to 5 hours. When the heating time is within the above range, uniform electrode catalyst particles tend to be formed.

  In the case of the stirring method, the heating time for the solid residue is usually 10 minutes to 5 hours, preferably 30 minutes to 2 hours. In this method, when continuous heating is performed, for example, by tilting the furnace, the average residence time calculated from the steady sample flow rate in the furnace is set as the heating time.

  In the case of the dropping method, the heating time of the solid residue is usually 0.5 to 10 minutes, preferably 0.5 to 3 minutes. When the heating time is within the above range, uniform electrode catalyst particles tend to be formed.

  In the case of the powder trapping method, the heating time of the solid residue is 0.2 seconds to 1 minute, preferably 0.2 to 10 seconds. When the heating time is within the above range, uniform electrode catalyst particles tend to be formed.

  When performing the heat treatment by the stationary method, a heating furnace using LNG (liquefied natural gas), LPG (liquefied petroleum gas), light oil, heavy oil, electricity, or the like as a heat source may be used as the heat treatment apparatus. In this case, since the atmosphere at the time of heat-treating the solid residue is important in the present invention, the fuel flame is present in the furnace, and is not heated from the inside of the furnace, but is heated from the outside of the furnace. An apparatus is preferred.

When using a heating furnace in which the amount of the solid content residue is 50 kg or more per batch, a heating furnace using LNG and LPG as a heat source is preferable from the viewpoint of cost.
When it is desired to obtain an electrode catalyst having a particularly high catalytic activity, it is desirable to use an electric furnace using electricity as a heat source and capable of strict temperature control.

  Examples of the shape of the furnace include a tubular furnace, an upper lid furnace, a tunnel furnace, a box furnace, a sample table raising / lowering furnace (elevator type), a cart furnace, and the like, and the atmosphere can be controlled particularly strictly. Tubular furnaces, top lid furnaces, box furnaces and sample table raising / lowering furnaces are preferred, and tubular furnaces and box furnaces are preferred.

  In the case of employing the stirring method, the above heat source can be used, but the scale of the equipment is large when the solid residue is continuously heat-treated by inclining the rotary kiln among the stirring methods. Therefore, it is preferable to use a heat source derived from a fuel such as LPG because the amount of energy used tends to increase.

  As an atmosphere at the time of performing the heat treatment, the main component is preferably an inert gas atmosphere from the viewpoint of enhancing the activity of the obtained electrode catalyst. Among the inert gases, nitrogen, argon, and helium are preferable and nitrogen and argon are more preferable because they are relatively inexpensive and easily available. These inert gas may be used individually by 1 type, and may mix and use 2 or more types. These gases are generally called inert gases, but during the heat treatment in the step (2), these inert gases, that is, nitrogen, argon, helium, and the like are separated from the solid residue. It may be reacting.

When a reactive gas is present in the atmosphere of the heat treatment, the obtained electrode catalyst may exhibit higher catalytic performance.
For example, the heat treatment is performed using nitrogen gas, argon gas, a mixed gas of nitrogen gas and argon gas, or one or more gases selected from nitrogen gas and argon gas and one or more gases selected from hydrogen gas, ammonia gas, and oxygen gas. When the reaction is performed in a mixed gas atmosphere, an electrode catalyst having high catalytic performance tends to be obtained.

  When hydrogen gas is contained in the atmosphere of the heat treatment, the concentration of hydrogen gas is, for example, 100% by volume or less, preferably 0.01 to 10% by volume, more preferably 1 to 5% by volume.

When oxygen gas is contained in the atmosphere of the heat treatment, the concentration of oxygen gas is, for example, 0.01 to 10% by volume, preferably 0.01 to 5% by volume.
When none of the transition metal-containing compound, the nitrogen-containing organic compound, and the solvent has an oxygen atom, the heat treatment is preferably performed in an atmosphere containing oxygen gas.

  The heat-treated product obtained by the heat treatment may be used as an electrode catalyst as it is, or may be used after being further crushed as an electrode catalyst. In the present specification, operations for making the heat-treated product fine, such as crushing and crushing, are referred to as “crushing” without any particular distinction. When pulverization is performed, it may be possible to improve the workability in producing an electrode using the obtained electrode catalyst and the characteristics of the obtained electrode. For this crushing, for example, a roll rolling mill, a ball mill, a small-diameter ball mill (bead mill), a medium stirring mill, an airflow grinder, a mortar, an automatic kneading mortar, a tank disintegrator, or a jet mill can be used. When the amount of the electrode catalyst is small, a mortar, an automatic kneading mortar, or a batch type ball mill is preferable. When a heat-treated product is continuously processed in a large amount, a jet mill or a continuous type ball mill is preferable, and a continuous type ball mill is used. Among these, a bead mill is more preferable.

The crushing is preferably performed under the following conditions.
(Crushing conditions): Impact force (mechanical energy) applied to the heat treatment is in the range of 2 to 100G.
When a ball mill is used, the rotational centrifugal acceleration is in the range of 2 to 20 G. Hereinafter, the crushing conditions will be described in more detail using a case where crushing is performed using a ball mill as an example.

  The above-mentioned crushing can be achieved even by using a batch type ball mill (pot type ball mill or the like) or a continuous type ball mill by setting an appropriate rotational centrifugal acceleration.

  If the acceleration generated by the rotation is 2G or more, the time for crushing can be shortened, which is advantageous for industrial production of the catalyst, and if it is 20G or less, the damage on the surface of the catalyst is reduced. A catalyst with high activity is obtained.

  When pulverization is performed using a ball mill of the type in which the slurry of the heat-treated product is circulated in the mill, that is, a continuous ball mill as exemplified by the Glen Mill manufactured by Asada Iron Works, the time for pulverization is substantially In addition, the heat treatment product is present in the ball crushing chamber (crushing chamber) of the ball mill. Therefore, when the volume of the slurry of the heat treated material circulated throughout the mill is twice the volume of the mill crushing chamber (crushing chamber), the “time for crushing with the ball mill” When the volume of the slurry of the heat-treated product circulated throughout the mill is three times the volume of the mill crushing chamber (crushing chamber), The “time for performing” is 1/3 of the actual operation time of the mill.

  The ball diameter of the ball mill is preferably 0.01 to 5.0 mm, more preferably 0.05 to 3.0 mm, and still more preferably 0.1 to 1.0 mm. When the ball diameter is in the above range, a fuel cell catalyst having high catalytic ability (oxygen reducing ability) can be obtained.

  Examples of the ball mill ball material and the ball mill container include zirconia, glass, and alumina. As a material of the ball, zirconia having high wear resistance is preferable.

The amount of balls added to the ball mill is preferably 10 to 100 times the mass of the heat-treated product placed in the mill vessel.
The rotational centrifugal acceleration at the time of crushing by the ball mill is preferably in the range of 2 to 20G, more preferably in the range of 4 to 18G, and further preferably in the range of 6 to 16G. When the rotational centrifugal acceleration is in the above range, a fuel cell catalyst having high catalytic ability (oxygen reducing ability) can be obtained.

In the present invention, the rotational centrifugal acceleration at the time of crushing by a ball mill is obtained from the following equation.
Rotational centrifugal acceleration (unit: gravitational acceleration G) = 1118 × R ₁ × N ₁ ² × 10 ⁻⁸
R ₁ : rotation radius (cm)
N ₁ : Rotational speed (rpm)

  When the ball mill is a planetary ball mill, the revolving centrifugal acceleration at the time of crushing by the planetary ball mill is preferably 5 to 50 G, more preferably 8 to 45 G, and still more preferably 10 to 10 G. The range is 35G. When the revolution centrifugal acceleration is in the above range, a fuel cell catalyst having high catalytic ability (oxygen reducing ability) can be obtained.

In addition, in this invention, the revolution centrifugal acceleration at the time of crushing by a planetary ball mill is calculated | required from the following formula | equation.
Revolving centrifugal acceleration (unit: gravity acceleration G) = 1118 × R ₂ × N ₂ ² × 10 ⁻⁸
R ₂ : Revolution radius (cm)
N ₂ : revolution speed (rpm)

  When the pulverization is performed in a wet manner, the mixing ratio of the heat-treated product and the dispersion medium (mass of the heat-treated product: mass of the dispersion medium) is preferably 1: 1 to 1:50, more preferably 1: 3 to 1. : 20, more preferably 1: 5 to 1:10.

Examples of the dispersion medium include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, pentaanol, and 2-heptanol. Alcohols such as benzyl alcohol;
Ketones such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isobutyl ketone, methyl amyl ketone, acetonyl acetone, diethyl ketone, dipropyl ketone, diisobutyl ketone;
Ethers such as tetrahydrofuran, diethylene glycol dimethyl ether, anisole, methoxytoluene, diethyl ether, dipropyl ether, dibutyl ether;
Amines such as isopropylamine, butylamine, isobutylamine, cyclohexylamine, diethylamine;
Esters such as propyl formate, isobutyl formate, amyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, isopentyl acetate;
Polar solvents such as acetonitrile, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, diethylene glycol and propylene glycol are preferred. These may be used alone or in combination of two or more.

The dispersion medium is preferably substantially free of water. Specifically, the content of water in the dispersion medium is preferably 0 to 0.1% by mass.
The dispersion medium is added so that preferably 30 to 30% of the entire mill container is filled with the heat-treated product and balls in the mill container.

Crushing in a dry process (that is, without using a dispersion medium) is preferable because the catalyst can be easily recovered after crushing.
The crushing is usually performed under normal temperature and normal pressure, but may be performed by adjusting the temperature and pressure.

(Electrocatalyst for fuel cell)
Transition metal elements constituting the electrode catalyst (a) for fuel cell (hereinafter also simply referred to as “electrode catalyst (a)”, “catalyst (a)”, etc.) produced in the catalyst production step (A) (however, transition The metal element M1 and the transition metal element M2 are not distinguished from each other.) When the ratio of the number of atoms of carbon, nitrogen, and oxygen is expressed as transition metal element: carbon: nitrogen: oxygen = 1: x: y: z, 0 <x ≦ 7, 0 <y ≦ 2, and 0 <z ≦ 3.

  Since the activity of the electrode catalyst is high, the range of x is more preferably 0.15 ≦ x ≦ 5.0, further preferably 0.2 ≦ x ≦ 4.0, and particularly preferably 1.0 ≦ x. ≦ 3.0, and the range of y is more preferably 0.01 ≦ y ≦ 1.5, still more preferably 0.02 ≦ y ≦ 0.5, and particularly preferably 0.03 ≦ y ≦ 0. And the range of z is more preferably 0.6 ≦ z ≦ 2.6, further preferably 0.9 ≦ z ≦ 2.0, and particularly preferably 1.3 ≦ z ≦ 1. .9.

  In addition, the catalyst includes, as the transition metal element, one transition metal element M1 selected from the group consisting of Group 4 and Group 5 elements of the periodic table, and iron, nickel, chromium, cobalt, vanadium, and manganese. In the case of containing at least one selected transition metal element M2, the ratio of the number of atoms of the transition metal element M1, transition metal element M2, carbon, nitrogen and oxygen constituting the catalyst is set to the transition metal element M1: transition. When expressed as metal element M2: carbon: nitrogen: oxygen = (1-a): a: x: y: z, 0 <a ≦ 0.5, 0 <x ≦ 7, 0 <y ≦ 2, 0 <z ≦ 3. When the catalyst contains M2 as described above, the performance becomes higher.

Since the activity of the electrode catalyst is high, the preferable ranges of x, y and z are as described above, and the range of a is more preferably 0.01 ≦ a ≦ 0.5, and further preferably 0.02 ≦ a. ≦ 0.4, particularly preferably 0.05 ≦ a ≦ 0.3.
The values of a, x, y and z are values measured by the method employed in the catalyst production example described later.

<Effect expected to be exhibited by the presence of transition metal element M2>
The effects expected due to the presence of the transition metal element M2 (at least one metal element selected from iron, nickel, chromium, cobalt, vanadium and manganese, which is different from M1) are as follows.

  (1) The transition metal element M2 or the compound containing the transition metal element M2 acts as a catalyst for forming a bond between the transition metal element M1 atom and the nitrogen atom when synthesizing the electrode catalyst.

  (2) Even when the electrode catalyst is used in a high potential, high oxidizing atmosphere where the transition metal element M1 is eluted, the transition metal element M2 is passivated to further increase the transition metal element M1. Prevent elution.

(3) During the heat treatment in step a3, sintering of the heat-treated product, that is, reduction in specific surface area is prevented.
(4) When the transition metal element M1 and the transition metal element M2 are present in the electrode catalyst, there is a bias of charge at the site where both metal element atoms are adjacent to each other, and only the transition metal element M1 is included as the metal element. Substrate adsorption or reaction, or product desorption, which cannot be achieved with an electrocatalyst, occurs.

  The catalyst preferably has atoms of a transition metal element, carbon, nitrogen, and oxygen, and has an oxide, carbide, nitride, or a plurality of crystal structures of the transition metal element. Judging from the results of the crystal structure analysis by X-ray diffraction analysis for the catalyst and the results of elemental analysis, the catalyst has oxygen oxide sites in the oxide structure while having the oxide structure of the transition metal element. A structure in which a carbon atom or a nitrogen atom is substituted, or a structure in which a site of a carbon atom or a nitrogen atom is substituted with an oxygen atom while having a carbide, nitride or carbonitride structure of the transition metal element, or It is speculated that it is a mixture containing these structures.

<BET specific surface area>
According to the catalyst production step (A), a fuel cell electrode catalyst having a large specific surface area is produced, and the specific surface area calculated by the BET method of the catalyst (a) is preferably 30 to 350 m ² / g. preferably 50 to 300 m ² / g, more preferably from 100 to 300 m ² / g.

In the following measurement method (A) of the catalyst, a potential at which a difference of 0.05 mA / cm ² or more begins to appear between the reduction current in an oxygen atmosphere and the reduction current in a nitrogen atmosphere (oxygen reduction potential E@0.05 mA / cm ² ) is preferably 0.6 V (vs. RHE) or higher, more preferably 0.7 V (vs. RHE) or higher, more preferably 0.8 V or higher, based on the reversible hydrogen electrode.

[Measurement method (A):
The catalyst and carbon are placed in a solvent so that the amount of the catalyst dispersed in carbon, which is an electron conductive material, is 1% by mass, and stirred with ultrasonic waves to obtain a suspension. As carbon, carbon black (specific surface area: 100 to 300 m ² / g) (for example, VULCAN (registered trademark) XC-72 manufactured by Cabot) is used, and the mass ratio of the catalyst and carbon is 95: 5. To disperse. As the solvent, isopropyl alcohol: water (mass ratio) = 2: 1 is used.

  10 μL of the suspension is collected while applying ultrasonic waves, quickly dropped onto a glassy carbon electrode (diameter: 5.2 mm), and dried at 120 ° C. for 5 minutes. By drying, a catalyst layer for a fuel cell containing the catalyst is formed on the glassy carbon electrode. This dropping and drying operation is performed until a 1.0 mg or more fuel cell catalyst layer is formed on the surface of the carbon electrode.

  Next, 10 μL of NAFION (registered trademark) (DuPont 5% NAFION (registered trademark) solution (DE521)) diluted 10-fold with isopropyl alcohol is further dropped onto the fuel cell catalyst layer. This is dried at 120 ° C. for 1 hour.

Thus, using the obtained electrode, a reversible hydrogen electrode in a sulfuric acid aqueous solution of the same concentration at a temperature of 30 ° C. in a 0.5 mol / L sulfuric acid aqueous solution in an oxygen atmosphere and a nitrogen atmosphere was used as a reference electrode. And a difference of 0.2 μA / cm ² or more appears between the reduction current in the oxygen atmosphere and the reduction current in the nitrogen atmosphere when the current-potential curve is measured by polarization at a potential scanning speed of 5 mV / sec. The starting potential is defined as the oxygen reduction starting potential. ]
In the present invention, the oxygen reduction current density can be determined as follows.

First, a difference between a reduction current in an oxygen atmosphere and a reduction current in a nitrogen atmosphere at a specific potential (for example, 0.7 V (vsRHE)) is calculated from the result of the measurement method (A). A value obtained by dividing the calculated value by the electrode area is defined as an oxygen reduction current density (mA / cm ² ).
The catalyst (a) produced in the catalyst production step (A) can be used as an alternative catalyst for the platinum catalyst.

[Catalyst paste]
The cathode catalyst paste used in the present invention contains particles of the fuel cell electrode catalyst (a) produced in the catalyst production step (A) as catalyst particles. Therefore, by using this cathode catalyst paste, it is possible to produce a membrane / electrode assembly at a lower cost compared to the case where a conventional catalyst paste containing a platinum catalyst or the like is used.

  This cathode catalyst paste can be produced by a method similar to the conventional method for producing an electrode catalyst paste, except that the particles of the fuel cell electrode catalyst (a) are used as catalyst particles.

  The anode catalyst paste used in the present invention may be a conventionally known electrode catalyst paste. Like the cathode catalyst paste, the anode catalyst paste is a catalyst paste containing a fuel cell electrode catalyst (a) as catalyst particles. There may be.

  The catalyst paste preferably further includes an electron conductive powder (electron conductive particles). When the catalyst paste further contains an electron conductive powder, the reduction current of the fuel cell 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.
The catalyst has a certain degree of conductivity, but in order to give more electrons to the catalyst, or in order for the reaction substrate to receive more electrons from the catalyst, the catalyst is mixed with carrier particles for imparting conductivity. Also good. These carrier particles may be mixed with the catalyst manufactured through the steps a1 to a3 in the catalyst manufacturing step (A), or may be mixed at any stage of the steps a1 to a3.

  Examples of the material of the electron conductive particles include carbon, a conductive polymer, a conductive ceramic, a metal, or a conductive inorganic oxide such as tungsten oxide or iridium oxide, which can be used alone or in combination. . In particular, since the electron conductive particles made of carbon have a large specific surface area, and are easily available with a small particle size at low cost, and are excellent in chemical resistance and high potential resistance, carbon alone or carbon and other electrons. A mixture with conductive particles is preferred. That is, the catalyst layer preferably contains the catalyst and carbon.

  Examples of carbon include carbon black, graphite, activated carbon, carbon nanotube, carbon nanofiber, carbon nanohorn, fullerene, porous carbon, and graphene. If the particle size of the electron conductive particles made of carbon is too small, it becomes difficult to form an electron conduction path. If the particle size is too large, the gas diffusibility of the fuel cell catalyst layer and the catalyst utilization rate tend to decrease. Therefore, it is preferably 10 to 1000 nm, more preferably 10 to 100 nm.

When the electron conductive particles are made of carbon, the weight ratio of the catalyst to the electron conductive particles (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) salt, polypyridine, polyquinoxaline, polyphenylquinoxaline and the like. Among these, polypyrrole, polyaniline, and polythiophene are preferable, and polypyrrole is more preferable.

  Examples of the solvent (dispersion medium) contained in the catalyst paste include water and compounds having a hydroxyl group such as ethyl alcohol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, t-butyl alcohol, and terpineol. These may be used as a mixture.

  The catalyst paste preferably further includes a polymer electrolyte. 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 (registered trademark)), a hydrocarbon polymer compound having a sulfonic acid group, a polymer doped with an inorganic acid such as phosphoric acid. Compounds, organic / inorganic hybrid polymers partially substituted with proton-conducting functional groups, proton conductors in which a polymer matrix is impregnated with a phosphoric acid solution or a sulfuric acid solution, etc. Among these, NAFION As a supply source of NAFION (registered trademark), a 5% NAFION (registered trademark) solution (DE521, DuPont) may be used.

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 step (B) and step (C). 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 component and the dispersant may be further dispersed at the same time.

[Method for producing membrane / electrode assembly and polymer electrolyte fuel cell]
Next, a method for producing a membrane / electrode assembly and a polymer electrolyte fuel cell of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
61 is a cross-sectional view for explaining the structure of the solid polymer fuel cell according to Embodiment 1 of the present invention, and FIG. 62 is the formation of an anode catalyst layer in the polymer electrolyte fuel cell according to Embodiment 1 of the present invention. FIG. 63 is a plan view showing a hot press surface of a mold applied to the method for manufacturing a membrane / electrode assembly of a polymer electrolyte fuel cell according to Embodiment 1. FIG. 64 is a side view for explaining a method for producing a membrane / electrode assembly of a polymer electrolyte fuel cell according to Embodiment 1. FIG. In FIG. 63, the concave grooves are shown in black for convenience of explanation.

  In FIG. 61, an anode catalyst layer 11 and a cathode catalyst layer 12 are arranged with a solid polymer electrolyte membrane 2 interposed therebetween, and are joined and integrated to constitute a power generation element body. As shown in FIG. 62, the anode catalyst layer 11 is formed on one surface of the solid polymer electrolyte membrane 2 with the catalyst formation region 11a separated by the catalyst non-formation region 11b and arranged in a matrix. . Similarly, the cathode catalyst layer 12 is formed on the other surface of the solid polymer electrolyte membrane 2 in which the catalyst formation region 12a is separated by the catalyst non-formation region 12b and arranged in a matrix. Further, the anode-side gas diffusion layer 5 and the cathode-side gas diffusion layer 6 are disposed in close contact with the anode catalyst layer 11 and the cathode catalyst layer 12 with the solid polymer electrolyte membrane 2 interposed therebetween, thereby constituting the membrane / electrode assembly 10. is doing.

  The pair of separator plates 7 and 8 having the gas flow paths 7a and 8a faces the gas flow paths 7a and 8a to the anode-side gas diffusion layer 5 and the cathode-side gas diffusion layer 6, respectively. It is arrange | positioned on both sides.

  The anode side gas diffusion layer 5 has a function of uniformly supplying the fuel gas to the anode catalyst layer 11 and collecting current. The anode side gas diffusion layer 6 constitutes an anode electrode together with the anode catalyst layer 11, and the cathode side gas diffusion layer 6 is an oxidizing agent. A gas is supplied uniformly to the cathode catalyst layer 12 and has a function of collecting current, and a cathode electrode is configured together with the cathode catalyst layer 12. For convenience of explanation, the polymer electrolyte fuel cell is shown as a single cell having a membrane / electrode assembly 10 sandwiched between separator plates 7 and 8. A plurality of bodies 10 and separator plates 7 and 8 are alternately stacked.

  Here, the solid polymer electrolyte membrane 2 is one that is stable in the environment in the fuel cell, has high proton conductivity and gas barrier property, and does not have electronic conductivity, and generally has a sulfone group in the perfluoro main chain. Those having an acid group bonded thereto can be used.

Further, a hydrocarbon electrolyte membrane, a membrane in which a polymer microporous membrane is impregnated with a liquid electrolyte, or a membrane in which a porous body is filled with a polymer electrolyte may be used.
The anode and cathode catalyst layers 11 and 12 are mainly composed of catalyst particles and a polymer electrolyte that exchanges ions with the catalyst. Furthermore, additives such as inorganic particles, polymer particles, and carbon particles may be mixed for the purpose of controlling the hydrophilicity and water repellency of the catalyst layer and improving the porosity.

In the present invention, as the catalyst particles constituting the cathode catalyst layer 12, the particles of the fuel cell electrode catalyst (a) produced in the catalyst production step (A) are used.
As the catalyst particles constituting the anode catalyst layer 11, the fuel cell electrode catalyst (a) particles produced in the catalyst production step (A) may be used, and conventionally known catalyst particles (for example, carbon black particle surfaces) May be used in which metal fine particles having catalytic activity such as platinum are supported.

  The anode-side and cathode-side gas diffusion layers 5 and 6 may be any conductive porous body that is stable even in the environment within the fuel cell. Generally, the anode-side and cathode-side gas diffusion layers 5 and 6 are porous formed of carbon fibers such as carbon paper and carbon cloth. The body is used.

  Alternatively, an aluminum foil coated with stainless steel or corrosion resistant material is used for weight reduction. Separator plates 7 and 8 may be any conductive plate that is stable even in the environment inside the fuel cell, and generally a carbon plate formed with gas flow channel grooves is used.

  In the polymer electrolyte fuel cell configured as described above, as shown in FIG. 62, the anode catalyst layer 11 has a solid structure in which the catalyst formation region 11a is separated by the catalyst non-formation region 11b and arranged in a matrix. An anode catalyst layer 11 is formed on one surface of the polymer electrolyte membrane 2, and the catalyst formation region 12 a is separated by the catalyst non-formation region 12 b and arranged in a matrix, on the other surface of the solid polymer electrolyte membrane 2. The cathode catalyst layer 12 is formed. The catalyst forming region 11a and the catalyst forming region 12a are formed in the same shape and at the same position with the solid polymer electrolyte membrane 2 interposed therebetween.

  Therefore, since the catalyst non-formation region 12b does not move water accompanying protons, it becomes a path through which water moves from the cathode side to the anode side. When the cathode catalyst layer 12 is in a state of local excess of water due to water generated by the cathode reaction and water carried from the anode side accompanying protons, excess water passes through the non-catalyst formation region 12b. Water is returned to the anode side, and the local excessive water state is eliminated. Further, the water in the excessive catalyst formation region 12a moves to the adjacent catalyst formation region 12a through the non-catalyst formation region 12b, and the local excessive water state is eliminated. As a result, the wet state of the cathode catalyst layer 12 becomes uniform, and the wet state of the solid polymer electrolyte membrane 2 becomes uniform.

As a result, even if the humidity of the supply gas is lowered, the solid polymer electrolyte 2 is prevented from being depleted of water, and a decrease in battery performance is suppressed.
Next, a method for manufacturing the membrane / electrode assembly 10 will be described with reference to FIGS. 63 and 64.

  First, the anode catalyst paste 15 is applied on the first transfer film 20 to a predetermined thickness and then dried. Similarly, the cathode catalyst paste 16 is applied to the second transfer film 21 to a predetermined thickness and then dried.

  Next, the dried anode catalyst paste 15 and cathode catalyst paste 16 face the solid polymer electrolyte membrane 2, and the first and second transfer films 20, 21 are sandwiched between the solid polymer electrolyte membranes 2. The stacked body 25 is produced by overlapping.

  Then, as shown in FIG. 64, the laminate 25 is disposed between the upper and lower molds 30 and 31 heated to a predetermined temperature, and the upper mold 30 is pressed against the lower mold 31. Here, the lower die 31 is formed on a hot press surface 31a that is flat on the entire surface. On the other hand, as shown in FIG. 63, the upper die 30 has concave grooves 30c as catalyst paste non-transfer portions formed vertically and horizontally at a predetermined pitch, and flat catalyst paste transfer portions 30b arranged in a matrix. The hot press surface 31a is formed.

  As a result, the areas of the anode catalyst base 15 and the cathode catalyst paste 16 pressed by the catalyst paste transfer part 30b bite into the solid polymer electrolyte membrane 2. Then, the upper mold 30 is removed, the first and second transfer films 20 and 21 are peeled off, and the regions of the anode catalyst base 15 and the cathode catalyst paste 16 pressed by the catalyst paste transfer portion 30b are solid polymer electrolyte membranes. 2 is transferred. Therefore, a power generation element body in which the catalyst formation regions 11a and 12a are respectively arranged in a matrix on both surfaces of the solid polymer electrolyte membrane 2 is obtained. Furthermore, the anode-side gas diffusion layer 5 and the cathode-side gas diffusion layer 6 are disposed on both sides of the power generation element body, whereby the membrane / electrode assembly 10 is obtained.

  According to the method of manufacturing the membrane / electrode assembly 10, the hot press surface 30a of the upper mold 30 is formed on the flat catalyst paste transfer portion 30b separated by the concave grooves 30c and arranged in a matrix. During hot pressing, a pressure distribution is formed by the upper mold 30, and the anode catalyst base 15 and the cathode catalyst paste 16 are transferred to the solid polymer electrolyte membrane 2 in a desired pattern. That is, the anode catalyst base 15 and the cathode catalyst paste 16 are transferred from the first and second transfer films 20 and 21 to the solid polymer electrolyte membrane 2 in the area pressed by the catalyst paste transfer portion 30b, and correspond to the concave groove 30c. The region to be pressed is not pressed and is not transferred to the solid polymer electrolyte 2. As a result, the anode catalyst layer 11 and the cathode catalyst layer 12 are configured in a matrix form by separating the catalyst formation regions 11a and 12a, and the membrane / electrode assembly 10 with improved water diffusion efficiency can be easily produced. . Further, since the catalyst forming region 11a and the catalyst forming region 12a are accurately formed in the same shape and at the same position with the solid polymer electrolyte membrane 2 interposed therebetween, a portion where the catalyst layer does not function does not occur.

  Further, since the transfer areas of the anode catalyst layer 11 and the cathode catalyst layer 12 are defined by the hot press surface 30a of the upper mold 30, the anode catalyst paste 15 and the cathode catalyst paste 16 are transferred to the first and second transfer films 20, 21. The area to be applied can be larger than the hot press surface 30a. Therefore, it is not necessary to accurately manage the application areas of the anode catalyst paste 15 and the cathode catalyst paste 16 on the first and second transfer films 20 and 21, and the application process of the anode catalyst paste 15 and the cathode catalyst paste 16 is simplified. Productivity.

  Moreover, since the anode catalyst paste 15 and the cathode catalyst paste 16 are transferred onto the solid polymer electrolyte 2 with the same position and shape, a complicated alignment step is not required, and the productivity is improved.

  Here, the first and second transfer films 20 and 21 may be any material that can withstand the temperature during hot pressing, is not affected by the solvent of the catalyst paste, and has strength to withstand manufacturing operations. For example, a PET (polyethylene terephthalate) film is used. The first and second films 20 and 21 are difficult to form a fine pattern when they are thick, and when they are thin, the strength is reduced and the handleability is deteriorated. Therefore, the thickness is preferably 50 μm or less and 10 μm or more.

  If the hot press temperature is too low, the anode and cathode catalyst pastes 15 and 16 and the solid polymer electrolyte membrane 2 are difficult to be integrated, and if too high, the solid polymer electrolyte membrane 2 is thermally deteriorated. . Therefore, when a typical perfluoro-based membrane such as Nafion (registered trademark), Flemion (registered trademark), or Aciplex (registered trademark) is used as the solid polymer electrolyte membrane 2, the hot press temperature is 120. What is necessary is just to set it to 140 degreeC or more and less than 170 degreeC more desirably.

  Further, when the thickness of the first and second transfer films 20 and 21 is large, if the groove width of the concave groove 30c is too narrow, accurate transfer of the catalyst paste cannot be performed due to dispersion of pressure during hot pressing. Therefore, the groove width of the concave groove 30c needs to be set appropriately according to the thickness of the transfer film.

  Moreover, when the area ratio of the catalyst paste non-transfer portion (concave groove 30c) is designed to be large, the areas of the catalyst formation regions 11a and 12a are reduced, and the performance per area of the power generation element body is deteriorated. Therefore, in order to ensure the performance per area of the power generating element body, the ratio of the area of the catalyst paste non-transfer portion to the area of the hot press surface 30a needs to be less than 30%, preferably less than 20%.

  In the first embodiment, the catalyst non-formation regions 11b and 12b are formed so as to divide the anode catalyst layer 11 and the cathode catalyst layer 12 into a matrix, but the catalyst non-formation region has this shape. For example, it may be formed in a dot shape. In this case, dot-shaped concave portions may be dispersedly formed on the hot press surface of the upper mold.

Embodiment 2. FIG.
FIG. 65 is a plan view of a main part for explaining the formation state of the cathode catalyst layer in the polymer electrolyte fuel cell according to Embodiment 2 of the present invention. FIG. 66 is a diagram of the polymer electrolyte fuel cell according to Embodiment 2. FIG. 67 is a plan view showing a hot press surface of a first mold applied to a method for manufacturing a membrane / electrode assembly, and FIG. 67 is a method for manufacturing a membrane / electrode assembly of a polymer electrolyte fuel cell according to Embodiment 2. FIG. 68 is a plan view showing a hot press surface of a second mold applied to the first embodiment, and FIG. 68 illustrates a first hot press step in the method for manufacturing a membrane / electrode assembly of a polymer electrolyte fuel cell according to the second embodiment. FIG. 69 is a side view of the main part for explaining the formation state of the cathode catalyst layer by the first hot pressing step in the method for manufacturing the membrane / electrode assembly of the polymer electrolyte fuel cell according to Embodiment 2. FIG. 70 shows the second embodiment. It is a side view illustrating a second hot-pressing process in the manufacturing method of the membrane electrode assembly of a polymer electrolyte fuel cell that. For convenience of explanation, in FIG. 65, the catalyst formation region is hatched, and in FIG. 66 and FIG. 67, the concave portion is shown in black.

  In FIG. 65, the cathode catalyst layer 13 includes a first catalyst formation region 13a that exhibits good performance under low humidification conditions and a second catalyst formation region 13b that exhibits good performance under high humidification conditions. They are separated by 13c, arranged in a matrix, and formed on the other surface of the solid polymer electrolyte membrane 2. The first and second catalyst formation regions 13a and 13b are formed in the same shape as opposed to the catalyst formation region 11a with the solid polymer electrolyte membrane 2 interposed therebetween.

Other configurations are the same as those in the first embodiment.
Also in the polymer electrolyte fuel cell using the membrane / electrode assembly configured as described above, the anode catalyst layer 11 and the cathode catalyst layer 13 are separated by the non-catalyst forming regions 11b and 13c and arranged in a matrix. Since the catalyst forming regions 11a, 13a, and 13b are configured, the catalyst non-forming regions 11b and 13c serve as a path for water movement, and the same effects as those of the first embodiment can be obtained.

  Further, the cathode catalyst layer 13 is configured by mixing the first catalyst formation region 13a that exhibits good performance under low humidification conditions and the second catalyst formation region 13b that exhibits good performance under high humidification conditions. Thus, a polymer electrolyte fuel cell that can cope with a wide range of humidification conditions can be realized.

Next, a method for producing a membrane / electrode assembly will be described with reference to FIGS.
First, the anode catalyst paste 15 is applied on the first transfer film 20 to a predetermined thickness and then dried. Moreover, after apply | coating the 1st cathode catalyst paste 17 which shows a favorable performance on low humidification conditions on the 2nd transfer film 21 to predetermined thickness, it dries. Further, the second cathode catalyst paste 18 showing good performance under high humidification conditions is applied on the third transfer film 22 to a predetermined thickness and then dried.

  Next, the anode catalyst paste 15 and the first cathode catalyst paste 17 face the solid polymer electrolyte membrane 2, and the first and second transfer films 20 and 21 are stacked so as to sandwich the solid polymer electrolyte membrane 2. Together, the laminate 26 is produced.

  Then, as shown in FIG. 68, the laminated body 26 is disposed between the upper and lower molds 32 and 31 heated to a predetermined temperature, and the upper mold 32 is pressed against the lower mold 31. Here, as shown in FIG. 66, in the upper mold 32, the flat first catalyst paste transfer portion 32b is separated by the concave portion 32c as the catalyst paste non-transfer portion, and the first catalyst formation region in FIG. The hot press surfaces 32a are arranged in an array pattern 13a. As a result, the areas of the anode catalyst base 15 and the first cathode catalyst paste 17 pressed by the catalyst paste transfer part 32 b bite into the solid polymer electrolyte membrane 2. Then, the upper mold 32 is removed, the first and second transfer films 20 and 21 are peeled off, and the regions of the anode catalyst base 15 and the first cathode catalyst paste 17 pressed by the catalyst paste transfer portion 32b are solid polymer. Transferred to the electrolyte membrane 2. At this time, on the other surface of the solid polymer electrolyte membrane 2, as shown in FIG. 69, the first catalyst formation regions 13a are arranged alternately. Although not shown, the catalyst formation region 11a is formed on the one surface of the solid polymer electrolyte membrane 2 in the same pattern as the first catalyst formation region 13a.

Subsequently, the 3rd transfer film 22 is piled up on the other surface side of the solid polymer electrolyte membrane 2, and the laminated body 27 is produced.
Then, as shown in FIG. 70, the laminated body 27 is disposed between the upper and lower molds 33 and 31 heated to a predetermined temperature, and the upper mold 33 is pressed against the lower mold 31. Here, as shown in FIG. 67, the upper mold 33 has a flat second catalyst paste transfer portion 33b separated by a recess 33c as a catalyst paste non-transfer portion, so that a second catalyst formation region in FIG. The hot press surfaces 33a are arranged in an array pattern 13b. As a result, the areas of the anode catalyst base 15 and the second cathode catalyst paste 18 pressed by the catalyst paste transfer part 33b bite into the solid polymer electrolyte membrane 2. Then, the upper mold 33 is removed, the first and third transfer films 20 and 22 are peeled off, and the regions of the anode catalyst base 15 and the second cathode catalyst paste 18 pressed by the catalyst paste transfer portion 33b are solid polymer. Transferred to the electrolyte membrane 2. As a result, the catalyst forming region 11a is arranged in a matrix on one surface of the solid polymer electrolyte membrane 2, and the first and second catalyst forming regions 13a and 13b are matrixed on the other surface of the solid polymer electrolyte membrane 2. A power generation element array arranged in a shape is obtained. Further, the anode-side gas diffusion layer 5 and the cathode-side gas diffusion layer 6 are disposed on both sides of the power generation element body, whereby a membrane-electrode assembly is obtained.

  According to this method of manufacturing a membrane / electrode assembly, the upper molds 32 and 33 having hot press surfaces 32a and 33a formed so that the first and second catalyst paste transfer portions 32b and 33b do not overlap each other are respectively provided. Since the hot pressing is performed twice, the anode catalyst layer 11 is formed by separating the catalyst formation regions 11a and arranged in a matrix, and the cathode catalyst layer 13 is formed by forming the first and second catalysts. The regions 13a and 13b are separated and arranged in a matrix. Therefore, as in the first embodiment, a membrane / electrode assembly with improved water diffusion efficiency can be easily produced. In addition, a membrane / electrode assembly having the cathode catalyst layer 13 in which catalyst layers having different compositions are mixed can be easily produced.

  Further, since the transfer areas of the anode catalyst layer 11 and the cathode catalyst layer 13 are defined by the hot press surfaces 32a and 33a of the upper molds 32 and 33, the anode catalyst paste 15, the first cathode catalyst paste 17 and the second cathode catalyst The region where the paste 18 is applied to the first, second and third transfer films 20, 21, 22 can be made larger than the hot press surfaces 32a, 33a. Therefore, it is not necessary to accurately manage the application areas of the anode catalyst paste 15, the first cathode catalyst paste 17, and the second cathode catalyst paste 18 on the first, second, and third transfer films 20, 21, and 22. The application process of the pastes 15, 17, and 18 is simplified, and productivity is improved.

  Further, since the anode catalyst paste 15 and the first and second cathode catalyst pastes 17 and 18 are transferred onto the solid polymer electrolyte 2 in the same position and shape, a complicated alignment step is not required, and productivity is increased. As a result, the non-functional portion of the catalyst layer does not occur.

  In the second embodiment, the cathode catalyst layer 13 is composed of two types of catalyst layers having different compositions. However, the cathode catalyst layer is composed of three or more types of catalyst layers having different compositions. Also good. In this case, the upper mold and the transfer film formed so that the catalyst paste transfer portion (catalyst formation region) does not overlap each other are prepared for several catalyst layers having different compositions, and the transfer film is stacked on the solid polymer electrolyte membrane 2. The process of hot pressing with the upper mold is repeated for several minutes of the catalyst layer.

  In the second embodiment, the cathode catalyst layer 13 is composed of two types of catalyst layers having different compositions. However, the anode catalyst layer may be composed of a plurality of catalyst layers having different compositions. Alternatively, both the anode and cathode catalyst layers may be composed of a plurality of catalyst layers having different compositions.

  In the second embodiment, if the laminate 26 is hot-pressed with the upper mold 32 and then hot-pressed with the upper mold 33 without peeling off the second transfer film 21, the anode catalyst paste 15 and the The anode catalyst layer and the cathode catalyst layer composed of one cathode catalyst paste 17 are formed by two hot pressing processes. In other words, if a plurality of upper molds formed so that the catalyst paste transfer portions do not overlap with each other are prepared, the anode catalyst layer and the cathode catalyst layer can be transferred and formed in the hot press process for the number of upper molds. it can.

  The fuel cell having the membrane-electrode assembly using the catalyst produced in the catalyst production step (A) has high performance and is very inexpensive compared to the case where platinum is used as a catalyst. Have. This fuel cell has at least one function selected from the group consisting of a power generation function, a light emission function, a heat generation function, a sound generation function, an exercise function, a display function, and a charging function, and particularly the performance of an article provided with a fuel cell. The performance of a simple article can be improved. The fuel cell is preferably provided on the surface or inside of an article.

<Specific examples of articles equipped with fuel cells>
Specific examples of the article that can include a fuel cell having a membrane / electrode assembly manufactured by the manufacturing method of the present invention include buildings, houses, buildings such as tents, fluorescent lamps, LEDs, etc., organic EL, Street lighting, indoor lighting, lighting equipment such as traffic lights, machines, automotive equipment including vehicles themselves, home appliances, agricultural equipment, electronic equipment, portable information terminals including mobile phones, beauty equipment, portable tools, bathroom accessories Sanitary equipment such as furniture, toys, decorative items, bulletin boards, cooler boxes, outdoor generators such as outdoor generators, teaching materials, artificial flowers, objects, power supplies for heart pacemakers, power supplies for heating and cooling devices with Peltier elements .

[Catalyst production example]
Below, the manufacture example of the catalyst manufactured at a catalyst manufacturing process (A) is shown.
Various measurements in the catalyst production examples and comparative catalyst production examples were performed by the following methods.

[Analysis method]
1. Powder X-ray diffraction Samples were subjected to powder X-ray diffraction using a rotor flex made by Rigaku Corporation.

The number of diffraction line peaks in powder X-ray diffraction of each sample was counted by regarding a signal that can be detected with a ratio (S / N) of signal (S) to noise (N) of 2 or more as one peak.
The noise (N) is the width of the baseline.

2. Elemental analysis Carbon: About 0.1 g of a sample was weighed and measured with Horiba EMIA-110.
Nitrogen / oxygen: About 0.1 g of a sample was weighed and sealed in Ni-Cup, and then measured with an ON analyzer.

Transition metal elements (titanium, etc.): About 0.1 g of a sample was weighed on a platinum dish, and acid was added for thermal decomposition. This heat-decomposed product was diluted, diluted, and quantified by ICP-MS.
3. BET specific surface area 0.15 g of a sample was sampled, and the specific surface area was measured with a fully automatic BET specific surface area measuring device Macsorb (manufactured by Mountec Co., Ltd.). The pretreatment time and pretreatment temperature were set at 30 ° C. and 200 ° C., respectively.

[Catalyst Production Example 1-1]
1. Production of catalyst Titanium tetraisopropoxide (Pure Chemical) 5mL and acetylacetone (Pure Chemical) 5mL are added to a solution of 15mL of ethanol (Wako Pure Chemical) and 5mL of acetic acid (Wako Pure Chemical). A solution was made. Further, 2.507 g of glycine (Wako Pure Chemical Industries, Ltd.) was added to 20 mL of pure water, and stirred at room temperature to completely dissolve it to prepare a glycine-containing mixture solution. The titanium-containing mixture solution was slowly added to the glycine-containing mixture solution to obtain a transparent catalyst precursor solution. Using a rotary evaporator, the temperature of the hot stirrer was set to about 100 ° C. under reduced pressure in a nitrogen atmosphere, and the solvent was slowly evaporated while heating and stirring the catalyst precursor solution. The solid residue obtained by completely evaporating the solvent was finely and uniformly crushed in a mortar to obtain a powder.

  This powder is put into a tubular furnace, and a heating rate of 10% in an atmosphere of a mixed gas of 4% by volume hydrogen and nitrogen (that is, hydrogen gas: nitrogen gas = 4% by volume: 96% by volume mixed gas, and so on). The powder (hereinafter also referred to as “catalyst (1)” or “heat-treated product (1)”) was obtained by heating at 900 ° C./min to 900 ° C., holding at 900 ° C. for 1 hour, and naturally cooling.

The powder X-ray diffraction spectrum of the catalyst (1) is shown in FIG. Diffraction line peaks of titanium compound with cubic structure and titanium oxide with rutile structure were observed.
In addition, Table 1 shows the results of elemental analysis of the catalyst (1). The presence of carbon, nitrogen and oxygen was confirmed.
The BET specific surface area of the catalyst (1) was 146 m ² / g.

[Catalyst Production Example 1-2]
1. Production of catalyst Titanium tetraisopropoxide (manufactured by Junsei Chemical Co., Ltd.) 5 mL and acetylacetone (genuine chemical) 5 mL of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) 15 mL and acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) 5 mL In addition to the solution, a titanium-containing mixture solution was prepared while stirring at room temperature. In addition, 2.507 g of glycine (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.153 g of iron acetate (manufactured by Aldrich) were added to 20 mL of pure water, and the mixture was stirred and completely dissolved at room temperature to prepare a glycine-containing mixture solution. . The titanium-containing mixture solution was slowly added to the glycine-containing mixture solution to obtain a transparent catalyst precursor solution. Using a rotary evaporator, the temperature of the hot stirrer was set to about 100 ° C. under reduced pressure in a nitrogen atmosphere, and the solvent was slowly evaporated while heating and stirring the catalyst precursor solution. The solid residue obtained by completely evaporating the solvent was finely and uniformly crushed in a mortar to obtain a powder.

  This powder is put into a tubular furnace, heated to 900 ° C. at a heating rate of 10 ° C./min in a mixed gas atmosphere of 4% by volume hydrogen and nitrogen, held at 900 ° C. for 1 hour, and naturally cooled to give a powder ( (Hereinafter also referred to as “catalyst (2)” or “heat-treated product (2)”).

The powder X-ray diffraction spectrum of the catalyst (2) is shown in FIG. Diffraction line peaks of titanium compound with cubic structure and titanium oxide with rutile structure were observed.
In addition, Table 1 shows the results of elemental analysis of the catalyst (2). The presence of carbon, nitrogen and oxygen was confirmed.
The BET specific surface area of the catalyst (2) was 172 m ² / g.

[Catalyst Production Example 1-3]
1. Production of catalyst 5 mL of titanium tetraisopropoxide (manufactured by Junsei Chemical Co., Ltd.) and 5 mL of acetylacetone (manufactured by Junsei Chemical Co., Ltd.) and 15 mL of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) and acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) ) In addition to the solution with 5 mL, a titanium-containing mixture solution was prepared while stirring at room temperature. In addition, 2.507 g of glycine (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.306 g of iron acetate (manufactured by Aldrich) were added to 20 mL of pure water and stirred at room temperature to be completely dissolved to prepare a glycine-containing mixture solution. . The titanium-containing mixture solution was slowly added to the glycine-containing mixture solution to obtain a clear solution. Using a rotary evaporator, the temperature of the hot stirrer was set to about 100 ° C. under reduced pressure in a nitrogen atmosphere, and the solvent was slowly evaporated while heating and stirring the solution. The solid residue obtained by completely evaporating the solvent was finely and uniformly crushed in a mortar to obtain a powder.

  This powder is put into a tubular furnace, heated to 900 ° C. at a heating rate of 10 ° C./min in an argon gas atmosphere, held at 900 ° C. for 1 hour, and naturally cooled to form a powder (hereinafter referred to as “catalyst (3)”). I wrote.)

The powder X-ray diffraction spectrum of the catalyst (3) is shown in FIG. Diffraction line peaks of titanium compound with cubic structure and titanium oxide with rutile structure were observed.
In addition, Table 1 shows the results of elemental analysis of the catalyst (3). The presence of carbon, nitrogen and oxygen was confirmed.
The BET specific surface area of the catalyst (3) was 181 m ² / g.

[Catalyst Production Example 1-4]
1. Production of catalyst 5 mL of titanium tetraisopropoxide (manufactured by Junsei Chemical Co., Ltd.) and 5 mL of acetylacetone (manufactured by Junsei Chemical Co., Ltd.) and 15 mL of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) and acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) ) In addition to the solution with 5 mL, a titanium-containing mixture solution was prepared while stirring at room temperature. Further, 1.254 g of glycine (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.153 g of iron acetate (manufactured by Aldrich) were added to 20 mL of pure water and stirred at room temperature to completely dissolve to prepare a glycine-containing mixture solution. . The titanium-containing mixture solution was slowly added to the glycine-containing mixture solution to obtain a transparent catalyst precursor solution. Using a rotary evaporator, the temperature of the hot stirrer was set to about 100 ° C. under reduced pressure in a nitrogen atmosphere, and the solvent was slowly evaporated while heating and stirring the catalyst precursor solution. The solid residue obtained by completely evaporating the solvent was finely and uniformly crushed in a mortar to obtain a powder.

  This powder is put in a tubular furnace, heated to 800 ° C. at a temperature rising rate of 10 ° C./min in an argon gas atmosphere, kept at 800 ° C. for 1 hour, and naturally cooled to form a powder (hereinafter referred to as “catalyst (4)”). I wrote.)

The powder X-ray diffraction spectrum of the catalyst (4) is shown in FIG. Diffraction line peaks of titanium compound with cubic structure and titanium oxide with rutile structure were observed.
In addition, Table 1 shows the elemental analysis results of the catalyst (4). The presence of carbon, nitrogen and oxygen was confirmed.
The BET specific surface area of the catalyst (4) was 181 m ² / g.

[Catalyst Production Example 1-5]
1. Production of catalyst 5 mL of titanium tetraisopropoxide (manufactured by Junsei Chemical Co., Ltd.) and 5 mL of acetylacetone (manufactured by Junsei Chemical Co., Ltd.) and 15 mL of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) and acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) ) In addition to the solution with 5 mL, a titanium-containing mixture solution was prepared while stirring at room temperature. Further, 2.507 g of glycine (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 20 mL of pure water, and stirred at room temperature to completely dissolve it to prepare a glycine-containing mixture solution. The titanium-containing mixture solution was slowly added to the glycine-containing mixture solution to obtain a transparent catalyst precursor solution. Using a rotary evaporator, the temperature of the hot stirrer was set to about 100 ° C. under reduced pressure in a nitrogen atmosphere, and the solvent was slowly evaporated while heating and stirring the catalyst precursor solution. The solid residue obtained by completely evaporating the solvent was finely and uniformly crushed in a mortar to obtain a powder.

  This powder is put into a tubular furnace, heated to 500 ° C. at a rate of temperature increase of 10 ° C./min in a 4% by volume hydrogen and nitrogen gas atmosphere, held at 500 ° C. for 2 hours, and naturally cooled to obtain a powder (hereinafter referred to as “catalyst”). (5) ") was obtained.

The powder X-ray diffraction spectrum of the catalyst (5) is shown in FIG. Diffraction line peaks of titanium compound with cubic structure and titanium oxide with rutile structure were observed.
In addition, Table 1 shows the results of elemental analysis of the catalyst (5). The presence of carbon, nitrogen and oxygen was confirmed.
The BET specific surface area of the catalyst (5) was 51 m ² / g.

[Catalyst Production Example 1-6]
1. Production of catalyst 5 mL of titanium tetraisopropoxide (manufactured by Junsei Chemical Co., Ltd.) and 3 mL of acetylacetone (manufactured by Junsei Chemical Co., Ltd.) and 15 mL of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) and acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) ) In addition to the solution with 5 mL, a titanium-containing mixture solution was prepared while stirring at room temperature. Moreover, 1.859 g of polyvinyl pyrrolidone (manufactured by Aldrich) and 0.145 g of iron acetate (manufactured by Aldrich) were added to 15 mL of pure water, and the mixture was stirred and completely dissolved at room temperature to prepare a glycine-containing mixture solution. The titanium-containing mixture solution was slowly added to the glycine-containing mixture solution to obtain a transparent catalyst precursor solution. Using a rotary evaporator, the temperature of the hot stirrer was set to about 100 ° C. under reduced pressure in a nitrogen atmosphere, and the solvent was slowly evaporated while heating and stirring the catalyst precursor solution. The solid residue obtained by completely evaporating the solvent was finely and uniformly crushed in a mortar to obtain a powder.

  This powder is put into a tubular furnace, heated to 900 ° C. at a temperature rising rate of 10 ° C./min in a nitrogen gas atmosphere, held at 900 ° C. for 3 hours, and naturally cooled to form a powder (hereinafter referred to as “catalyst (6)”). I wrote.)

The powder X-ray diffraction spectrum of the catalyst (6) is shown in FIG. Diffraction line peaks of titanium compound with cubic structure and titanium oxide with rutile structure were observed.
In addition, Table 1 shows the elemental analysis results of the catalyst (6). The presence of carbon, nitrogen and oxygen was confirmed.
The BET specific surface area of the catalyst (6) was 260 m ² / g.

[Catalyst Production Example 1-7]
1. Production of catalyst Titanium tetraisopropoxide (manufactured by Junsei Co., Ltd.) is added to a solution of 15 mL of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) and 5 mL of acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) and stirred at room temperature. A titanium-containing mixture solution was prepared. Moreover, 1.859 g of polyvinyl pyrrolidone (manufactured by Aldrich) and 0.145 g of iron acetate (manufactured by Aldrich) were added to 15 mL of pure water and stirred at room temperature to completely dissolve it to prepare a glycine-containing mixture solution. The titanium-containing mixture solution was slowly added to the glycine-containing mixture solution to obtain a transparent catalyst precursor solution. Using a rotary evaporator, the temperature of the hot stirrer was set to about 100 ° C. under reduced pressure in a nitrogen atmosphere, and the solvent was slowly evaporated while heating and stirring the catalyst precursor solution. The solid residue obtained by completely evaporating the solvent was finely and uniformly crushed in a mortar to obtain a powder.

  This powder is put into a tubular furnace, heated to 600 ° C. at a temperature rising rate of 10 ° C./min in a nitrogen gas atmosphere, held at 600 ° C. for 2 hours, and naturally cooled to form a powder (hereinafter referred to as “catalyst (7)”). I wrote.)

The powder X-ray diffraction spectrum of the catalyst (7) is shown in FIG. Diffraction line peaks of titanium compound with cubic structure and titanium oxide with rutile structure were observed.
In addition, Table 1 shows the elemental analysis results of the catalyst (7). The presence of carbon, nitrogen and oxygen was confirmed.
The BET specific surface area of the catalyst (7) was 65 m ² / g.

[Catalyst Production Example 1-8]
1. Production of catalyst 5 mL of titanium tetraisopropoxide (manufactured by Junsei Chemical Co., Ltd.) and 5 mL of acetylacetone (manufactured by Junsei Chemical Co., Ltd.) and 15 mL of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) and acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) ) In addition to the solution with 5 mL, a titanium-containing mixture solution was prepared while stirring at room temperature. Further, 3.762 g of glycine (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.306 g of iron acetate (manufactured by Aldrich) were added to 20 mL of pure water, and the mixture was stirred at room temperature and completely dissolved to prepare a glycine-containing mixture solution. . The titanium-containing mixture solution was slowly added to the glycine-containing mixture solution to obtain a transparent catalyst precursor solution. Using a rotary evaporator, the temperature of the hot stirrer was set to about 100 ° C. under reduced pressure in a nitrogen atmosphere, and the solvent was slowly evaporated while heating and stirring the catalyst precursor solution. The solid residue obtained by completely evaporating the solvent was finely and uniformly crushed in a mortar to obtain a powder.

  This powder was put into a tubular furnace, heated to 900 ° C. at a heating rate of 10 ° C./min in a mixed gas atmosphere of 4% by volume hydrogen and nitrogen, held at 900 ° C. for 1 hour, and naturally cooled to obtain a powder (hereinafter referred to as “powder”). "Catalyst (8)") was obtained.

The powder X-ray diffraction spectrum of the catalyst (8) is shown in FIG. Diffraction line peaks of titanium compound with cubic structure and titanium oxide with rutile structure were observed.
In addition, Table 1 shows the elemental analysis results of the catalyst (8). The presence of carbon, nitrogen and oxygen was confirmed.
The BET specific surface area of the catalyst (8) was 241 m ² / g.

[Catalyst Production Example 2-1]
1. Production of Fuel Cell Electrode A catalyst (2) (0.095 g) and carbon (Cabot XC-72) (0.005 g) were mixed in a mass ratio of isopropyl alcohol: pure water = 2: 1 and mixed with 10 g. The mixture was stirred and suspended by sonic waves. 30 μl of the mixture was applied to a glassy carbon electrode (Tokai Carbon Co., Ltd., diameter: 5.2 mm) and dried at 120 ° C. for 1 hour to form a fuel cell catalyst layer of 1.0 mg or more on the carbon electrode surface. Furthermore, 10 μl of NAFION (registered trademark) (DuPont 5% NAFION (registered trademark) solution (DE521)) diluted 10-fold with isopropyl alcohol was applied on the catalyst layer for the fuel cell, and the mixture was applied at 120 ° C. for 1 hour. It dried and obtained the electrode (1) for fuel cells.

2. Evaluation of oxygen reduction ability 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 a potential scanning speed of 30 ° C. and 5 mV / sec. A potential curve 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 above measurement results, a potential at which a difference of 0.2 μA / cm ² or more began to appear between the reduction current in the oxygen atmosphere and the reduction current in the nitrogen atmosphere was defined as the oxygen reduction start potential. Further, the difference between the reduction current in an oxygen atmosphere and the reduction current in a nitrogen atmosphere at 0.7 V (vs RHE) was calculated. A value obtained by further dividing the calculated value by the electrode area was defined as an oxygen reduction current density (mA / cm ² ).

The catalytic ability of the produced fuel cell electrode (1) was evaluated based on the oxygen reduction starting potential and the oxygen reduction current density.
That is, the higher the oxygen reduction start potential and the higher the oxygen reduction current density, the higher the catalytic performance of the catalyst in the fuel cell electrode.

FIG. 9 shows a current-potential curve obtained by the above measurement.
The catalyst (2) produced in Catalyst Production Example 1-2 has an oxygen reduction starting potential of 1.01 V (vs. RHE), an oxygen reduction current density of 1.28 mA / cm ² , and has high catalytic ability. Okay (Table 2).

[Catalyst Production Example 2-2]
1. Production of Fuel Cell Electrode A catalyst (3) (0.095 g) and carbon (Cabot XC-72) (0.005 g) were mixed in a mass ratio of isopropyl alcohol: pure water = 2: 1 and mixed with 10 g. The mixture was stirred and suspended by sonic waves. 30 μl of the mixture was applied to a glassy carbon electrode (Tokai Carbon Co., Ltd., diameter: 5.2 mm) and dried at 120 ° C. for 1 hour to form a fuel cell catalyst layer of 1.0 mg or more on the carbon electrode surface. Furthermore, 10 μl of NAFION (registered trademark) (DuPont 5% NAFION (registered trademark) solution (DE521)) diluted 10-fold with isopropyl alcohol was applied on the catalyst layer for the fuel cell, and the mixture was applied at 120 ° C. for 1 hour. It dried and obtained the electrode (2) for fuel cells.

2. Evaluation of oxygen reduction ability The produced fuel cell electrode (2) was polarized in an oxygen atmosphere and a nitrogen atmosphere in a 0.5 mol / dm ³ sulfuric acid solution at a potential scanning rate of 5 mV / sec at 30 ° C. A potential curve 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 above measurement results, a potential at which a difference of 0.2 μA / cm ² or more began to appear between the reduction current in the oxygen atmosphere and the reduction current in the nitrogen atmosphere was defined as the oxygen reduction start potential. Further, the difference between the reduction current in an oxygen atmosphere and the reduction current in a nitrogen atmosphere at 0.7 V (vs RHE) was calculated. A value obtained by further dividing the calculated value by the electrode area was defined as an oxygen reduction current density (mA / cm ² ).

The catalytic ability of the produced fuel cell electrode (2) was evaluated based on the oxygen reduction starting potential and the oxygen reduction current density.
That is, the higher the oxygen reduction start potential and the higher the oxygen reduction current density, the higher the catalytic performance of the catalyst in the fuel cell electrode.

FIG. 10 shows a current-potential curve obtained by the above measurement.
The catalyst (3) produced in Catalyst Production Example 1-3 has an oxygen reduction starting potential of 1.01 V (vs. RHE), an oxygen reduction current density of 1.90 mA / cm ² , and has high catalytic ability. Okay (Table 2).

[Catalyst Production Example 2-3]
1. Production of Fuel Cell Electrode A catalyst (6) 0.095 g and carbon (XC-72 manufactured by Cabot Corporation) 0.005 g were mixed in 10 g of a solution having a mass ratio of isopropyl alcohol: pure water = 2: 1. The mixture was stirred and suspended by sonic waves. 30 μl of the mixture was applied to a glassy carbon electrode (Tokai Carbon Co., Ltd., diameter: 5.2 mm) and dried at 120 ° C. for 1 hour to form a fuel cell catalyst layer of 1.0 mg or more on the carbon electrode surface. Furthermore, 10 μl of NAFION (registered trademark) (DuPont 5% NAFION (registered trademark) solution (DE521)) diluted 10-fold with isopropyl alcohol was applied on the catalyst layer for the fuel cell, and the mixture was applied at 120 ° C. for 1 hour. It dried and obtained the electrode (3) for fuel cells.

2. Evaluation of oxygen reduction ability The produced fuel cell electrode (3) was polarized in an oxygen atmosphere and a nitrogen atmosphere in a 0.5 mol / dm ³ sulfuric acid solution at a potential scanning speed of 30 ° C. and 5 mV / sec. A potential curve 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 above measurement results, a potential at which a difference of 0.2 μA / cm ² or more began to appear between the reduction current in the oxygen atmosphere and the reduction current in the nitrogen atmosphere was defined as the oxygen reduction start potential. Further, the difference between the reduction current in an oxygen atmosphere and the reduction current in a nitrogen atmosphere at 0.7 V (vs RHE) was calculated. A value obtained by further dividing the calculated value by the electrode area was defined as an oxygen reduction current density (mA / cm ² ).

The catalytic ability of the produced fuel cell electrode (3) was evaluated based on the oxygen reduction starting potential and the oxygen reduction current density.
That is, the higher the oxygen reduction start potential and the higher the oxygen reduction current density, the higher the catalytic performance of the catalyst in the fuel cell electrode.

FIG. 11 shows a current-potential curve obtained by the above measurement.
The catalyst (6) produced in Catalyst Production Example 1-6 has an oxygen reduction starting potential of 1.04 V (vs. RHE), an elementary reduction current density of 0.68 mA / cm ² , and has high catalytic ability. Okay (Table 2).

[Catalyst Production Example 2-4]
1. Production of Fuel Cell Electrode A catalyst (7) 0.095 g and carbon (Cabot XC-72) 0.005 g were mixed in 10 g of a solution in which the mass ratio of isopropyl alcohol: pure water = 2: 1 was The mixture was stirred and suspended by sonic waves. 30 μl of the mixture was applied to a glassy carbon electrode (Tokai Carbon Co., Ltd., diameter: 5.2 mm) and dried at 120 ° C. for 1 hour to form a fuel cell catalyst layer of 1.0 mg or more on the carbon electrode surface. Furthermore, 10 μl of NAFION (registered trademark) (DuPont 5% NAFION (registered trademark) solution (DE521)) diluted 10-fold with isopropyl alcohol was applied on the catalyst layer for the fuel cell, and the mixture was applied at 120 ° C. for 1 hour. It dried and obtained the electrode (4) for fuel cells.

2. Evaluation of oxygen reduction ability The produced fuel cell electrode (4) was polarized in an oxygen atmosphere and a nitrogen atmosphere in a 0.5 mol / dm ³ sulfuric acid solution at a potential scanning speed of 30 ° C. and 5 mV / sec. A potential curve 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 above measurement results, a potential at which a difference of 0.2 μA / cm ² or more began to appear between the reduction current in the oxygen atmosphere and the reduction current in the nitrogen atmosphere was defined as the oxygen reduction start potential. Further, the difference between the reduction current in an oxygen atmosphere and the reduction current in a nitrogen atmosphere at 0.7 V (vs RHE) was calculated. A value obtained by further dividing the calculated value by the electrode area was defined as an oxygen reduction current density (mA / cm ² ).

The catalytic ability of the produced fuel cell electrode (4) was evaluated based on the oxygen reduction starting potential and the oxygen reduction current density.
That is, the higher the oxygen reduction start potential and the higher the oxygen reduction current density, the higher the catalytic performance of the catalyst in the fuel cell electrode.

FIG. 12 shows a current-potential curve obtained by the above measurement.
The catalyst (7) produced in Catalyst Production Example 1-7 has an oxygen reduction starting potential of 0.82 V (vs. RHE), an oxygen reduction current density of 0.4 mA / cm ² , and has high catalytic ability. Okay (Table 2).

[Catalyst Production Example 2-5]
1. Production of Fuel Cell Electrode 0.095 g of catalyst (8) and 0.005 g of carbon (XC-72 manufactured by Cabot Corporation) were put in 10 g of a solution mixed in a mass ratio of isopropyl alcohol: pure water = 2: 1. The mixture was stirred and suspended by sonic waves. 30 μl of the mixture was applied to a glassy carbon electrode (Tokai Carbon Co., Ltd., diameter: 5.2 mm) and dried at 120 ° C. for 1 hour to form a fuel cell catalyst layer of 1.0 mg or more on the carbon electrode surface. Furthermore, 10 μl of NAFION (registered trademark) (DuPont 5% NAFION (registered trademark) solution (DE521)) diluted 10-fold with isopropyl alcohol was applied on the catalyst layer for the fuel cell, and the mixture was applied at 120 ° C. for 1 hour. It dried and obtained the electrode (5) for fuel cells.

2. Evaluation of oxygen reduction ability The produced fuel cell electrode (5) was polarized in an oxygen atmosphere and a nitrogen atmosphere in a 0.5 mol / dm ³ sulfuric acid solution at a potential scanning speed of 30 ° C. and 5 mV / sec. A potential curve 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 above measurement results, a potential at which a difference of 0.2 μA / cm ² or more began to appear between the reduction current in the oxygen atmosphere and the reduction current in the nitrogen atmosphere was defined as the oxygen reduction start potential. Further, the difference between the reduction current in an oxygen atmosphere and the reduction current in a nitrogen atmosphere at 0.7 V (vs RHE) was calculated. A value obtained by further dividing the calculated value by the electrode area was defined as an oxygen reduction current density (mA / cm ² ).

The catalytic ability of the produced fuel cell electrode (5) was evaluated based on the oxygen reduction starting potential and the oxygen reduction current density.
That is, the higher the oxygen reduction start potential and the higher the oxygen reduction current density, the higher the catalytic performance of the catalyst in the fuel cell electrode.

FIG. 13 shows a current-potential curve obtained by the above measurement.
The catalyst (8) produced in Catalyst Production Example 1-8 has an oxygen reduction starting potential of 0.95 V (vs. RHE), an oxygen reduction current density of 1.50 mA / cm ² , and has high catalytic ability. Okay (Table 2).

[Catalyst Production Example 3-1]
1. Production of catalyst As the first transition metal-containing compound, 9.37 g of titanium tetraisopropoxide (manufactured by Junsei Kagaku Co., Ltd.) and 5.12 g of acetylacetone (Junsei Kagaku) 15 mL of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) and acetic acid In addition to a solution with 5 mL (Wako Pure Chemical Industries, Ltd.), a first transition metal-containing mixture solution was prepared while stirring at room temperature. Further, 10.0 g of glycine (manufactured by Wako Pure Chemical Industries, Ltd.) as a nitrogen-containing organic compound and 0.582 g of iron acetate (manufactured by Aldrich) as a second transition metal-containing compound are added to 20 mL of pure water and stirred at room temperature. And completely dissolved to prepare a nitrogen-containing organic compound-containing mixture solution. The first transition metal-containing mixture solution was slowly added to the nitrogen-containing organic compound-containing mixture solution to obtain a transparent catalyst precursor solution. Using a rotary evaporator, the temperature of the hot stirrer was set to about 100 ° C. under reduced pressure in a nitrogen atmosphere, and the solvent was slowly evaporated while heating and stirring the catalyst precursor solution. The solid residue obtained by completely evaporating the solvent was finely and uniformly crushed in a mortar to obtain a powder.

  This powder is put into a tubular furnace, heated to 890 ° C. at a heating rate of 10 ° C./min in an atmosphere of nitrogen gas containing 4% by volume of hydrogen gas, held at 890 ° C. for 1 hour, and naturally cooled to form powder The catalyst was obtained. Table 3 shows the BET specific surface area and elemental analysis results of this catalyst.

2. Production of Fuel Cell Electrode Next, 0.095 g of this catalyst and 0.005 g of carbon (XC-72 manufactured by Cabot Corporation) were mixed in 10 g of a solution having a mass ratio of isopropyl alcohol: pure water = 2: 1, The mixture was stirred and suspended by sonic waves. 30 μl of the mixture was applied to a glassy carbon electrode (Tokai Carbon Co., Ltd., diameter: 5.2 mm) and dried at 120 ° C. for 5 minutes to form a fuel cell catalyst layer of 1.0 mg or more on the surface of the carbon electrode. Further, 10 μl of NAFION (registered trademark) (DuPont 5% NAFION (registered trademark) solution (DE521)) diluted 10-fold with isopropyl alcohol was applied on the catalyst layer for the fuel cell, and the mixture was applied at 120 ° C. for 1 hour. It dried and obtained the electrode for fuel cells.

3. Evaluation of oxygen reduction ability The prepared fuel cell electrode was polarized in an oxygen and nitrogen atmosphere in a 0.5 mol / L sulfuric acid aqueous solution at 30 ° C. and a potential scanning rate of 5 mV / sec, and a current-potential curve was measured. did. At that time, a reversible hydrogen electrode in a sulfuric acid solution having the same concentration was used as a reference electrode. The reduction current and a 0.05 mA / cm ² or more differences begin to appear potential at reduction current and a nitrogen atmosphere in an oxygen atmosphere was oxygen reduction potential E@0.05mA/cm ^2. Based on this oxygen reduction potential, the catalytic ability of the produced fuel cell electrode was evaluated. That is, the higher the oxygen reduction potential, the higher the catalytic ability of the catalyst in the fuel cell electrode.

[Catalyst Production Examples 3-2 to 3-26, 3-29 to 3-38, Comparative Catalyst Production Examples 3-1 to 3-3]
The same as Catalyst Production Example 3-1, except that the compounds described in Table 3 were used in the weights described in Table 3 as the first transition metal-containing compound, nitrogen-containing organic compound, and second transition metal-containing compound. The catalyst was produced by the above procedure and analyzed, and a fuel cell electrode was obtained and its oxygen reduction ability was evaluated. The results are shown in Table 3.

[Catalyst Production Examples 3-27 to 3-28]
1. Production of Catalyst Catalyst Production Example 3 except that the compounds described in Table 3 were used as the first transition metal-containing compound, the nitrogen-containing organic compound, and the second transition metal-containing compound in the weight described in Table 3. A transparent catalyst precursor solution was obtained by the same procedure as in 1. Using a rotary evaporator, the temperature of the hot stirrer was set to about 100 ° C. under reduced pressure in a nitrogen atmosphere, and the catalyst precursor solution was heated and stirred to slowly evaporate the solvent until the amount of the solution was reduced to half. The solid precipitated in the solution was taken out by filtration, and the solid residue obtained by drying the solid in nitrogen was finely and uniformly crushed in a mortar to obtain a powder.

  This powder is put into a tubular furnace, heated to 890 ° C. at a heating rate of 10 ° C./min in an atmosphere of nitrogen gas containing 4% by volume of hydrogen gas, held at 890 ° C. for 1 hour, and naturally cooled to form powder The catalyst was prepared and analyzed, and a fuel cell electrode was obtained and its oxygen reduction ability was evaluated. The results are shown in Table 3.

[Catalyst Production Example 3-39]
Except that the heating temperature was changed from 890 ° C. to 1000 ° C., a catalyst was produced in the same procedure as in Catalyst Production Example 3-1, analyzed, and a fuel cell electrode was obtained to evaluate its oxygen reducing ability. did. The results are shown in Table 3.

[Catalyst Production Example 3-40]
The compounds described in Table 3 as the first transition metal-containing compound, nitrogen-containing organic compound, and second transition metal-containing compound are used in the weights described in Table 3, and methanol (special grade, Wako Chemical) is used instead of ethanol. A catalyst was produced in the same procedure as in Catalyst Production Example 3-1, except that 50 ml was used and no acetic acid was used. The catalyst was analyzed, and a fuel cell electrode was obtained to evaluate its oxygen reducing ability. The results are shown in Table 3.

[Catalyst Production Example 3-41]
1. Production of catalyst 2.60 g of acetylacetone was placed in a beaker, and 4.30 g of vanadium isopropoxide as a first transition metal-containing compound was added dropwise with stirring, and 28 ml of acetic acid was added dropwise over 2 minutes. A transition metal-containing mixture solution was prepared.

  In a beaker, 60 ml of water, 50 ml of ethanol, and 60 ml of acetic acid were added, and 8.74 g of pyrazinecarboxylic acid was added as a nitrogen-containing organic compound and completely dissolved. While stirring this, 0.290 g of iron acetate was further added to the obtained solution little by little and dissolved. Next, while maintaining the temperature at room temperature and with stirring, the first transition metal-containing mixture solution is dropped slowly (over 10 minutes), and after the dropping, stirring is further performed for 30 minutes to obtain a transparent catalyst precursor solution (3 -41) was obtained.

  Using a rotary evaporator, the temperature of the hot stirrer was set to about 100 ° C. under reduced pressure in a nitrogen atmosphere, and the solvent was slowly evaporated while heating and stirring the catalyst precursor solution. The solid residue obtained by completely evaporating the solvent was finely and uniformly crushed in a mortar to obtain a powder.

  1.2 g of this powder was placed in a rotary kiln furnace, heated to 890 ° C. at a temperature rising rate of 10 ° C./min while flowing nitrogen gas containing 4% by volume of hydrogen gas at a rate of 20 ml / min, and 0 at 890 ° C. The powdered catalyst was obtained by holding for 5 hours and naturally cooling. Table 3 shows the BET specific surface area and elemental analysis results of this catalyst.

[Catalyst Production Example 3-42]
Into a beaker, 80 ml of acetic acid was added, and 6.13 g of vanadium (III) acetylacetonate was added dropwise with stirring to prepare a first transition metal-containing mixture solution.

  In a 500 ml eggplant flask containing one stir bar (length 30 mm), 60 ml of water, 50 ml of ethanol, and 60 ml of acetic acid are added, and 8.74 g of pyrazinecarboxylic acid is added as a nitrogen-containing organic compound and completely dissolved. It was. While stirring this, 0.290 g of iron acetate was further added to the obtained solution little by little and dissolved. Next, while maintaining the temperature at room temperature and with stirring, the first transition metal-containing mixture solution is dropped slowly (over 10 minutes), and after the dropping, stirring is further performed for 30 minutes to obtain a transparent catalyst precursor solution (3 -42) was obtained.

  A powdery catalyst was obtained by the same operation as in Catalyst Production Example 3-41 except that the catalyst precursor solution (3-41) was changed to the catalyst precursor solution (3-42). Table 3 shows the BET specific surface area and elemental analysis results of this catalyst.

[Catalyst Production Example 3-43]
1. Production of catalyst As the first transition metal-containing compound, 9.37 g of titanium tetraisopropoxide (manufactured by Junsei Kagaku Co., Ltd.) and 5.12 g of acetylacetone (Junsei Kagaku) are mixed with 5 mL of acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) In addition to the solution, a first transition metal-containing mixture solution was prepared while stirring at room temperature. Further, 10.0 g of glycine (manufactured by Wako Pure Chemical Industries, Ltd.) as a nitrogen-containing organic compound and 0.582 g of iron acetate (manufactured by Aldrich) as a second transition metal-containing compound are added to 20 mL of pure water and stirred at room temperature. And completely dissolved to prepare a nitrogen-containing organic compound-containing mixture solution. The first transition metal-containing mixture solution was slowly added to the nitrogen-containing organic compound-containing mixture solution to obtain a transparent catalyst precursor solution. Using a rotary evaporator, the temperature of the hot stirrer was set to about 80 ° C. under reduced pressure in a nitrogen atmosphere, and the solvent was slowly evaporated while heating and stirring the catalyst precursor solution. The solid residue obtained by completely evaporating the solvent was finely and uniformly crushed in a mortar to obtain a powder.

  This powder is put into a tube furnace, heated to 890 ° C. at a temperature rising rate of 20 ° C./min in an atmosphere of nitrogen gas containing 4% by volume of hydrogen gas, held at 890 ° C. for 30 minutes, and naturally cooled to form powder. The catalyst was obtained. Table 3 shows the BET specific surface area and elemental analysis results of this catalyst.

[Comparative Catalyst Production Example 3-4]
Titanium oxide (anatase type, 100 m ² / g), which is a transition metal-containing compound, is placed in a tubular furnace, heated to 900 ° C. at a temperature rising rate of 10 ° C./min in an atmosphere of nitrogen gas containing 4% by volume of hydrogen gas, A powdery catalyst was produced by holding at 900 ° C. for 1 hour and naturally cooling. The analysis was carried out to obtain a fuel cell electrode, and its oxygen reduction ability was evaluated. The results are shown in Table 3.

[Comparative Catalyst Production Example 3-5]
² g of titanium oxide (anatase type, 100 m ² / g) which is a transition metal-containing compound and 0.75 g of carbon black (manufactured by Cabot, VULCAN (registered trademark) XC72) are mixed well in a mortar, put in a tube furnace, and hydrogen In a nitrogen gas atmosphere containing 4% by volume of gas, the catalyst was heated to 1700 ° C. at a heating rate of 10 ° C./min, held at 1700 ° C. for 3 hours, and naturally cooled to produce a powdered catalyst. The analysis was carried out to obtain a fuel cell electrode, and its oxygen reduction ability was evaluated. The results are shown in Table 3.

[Comparative Catalyst Production Example 3-6]
The powder obtained in Catalyst Production Example 3-1 is placed in a tubular furnace, heated to 170 ° C. at a temperature rising rate of 10 ° C./min in an atmosphere of nitrogen gas containing 4% by volume of hydrogen gas, and held at 170 ° C. for 1 hour. A powdered catalyst was produced by natural cooling. The analysis was carried out to obtain a fuel cell electrode, and its oxygen reduction ability was evaluated. The results are shown in Table 4.

[Comparative Catalyst Production Example 3-7]
The powder obtained in Catalyst Production Example 3-1 is placed in a tubular furnace, heated to 240 ° C. at a temperature rising rate of 10 ° C./min in an atmosphere of nitrogen gas containing 4% by volume of hydrogen gas, and held at 240 ° C. for 1 hour. A powdered catalyst was produced by natural cooling. The analysis was carried out to obtain a fuel cell electrode, and its oxygen reduction ability was evaluated. The results are shown in Table 4.

[Comparative Catalyst Production Example 3-8]
The powder obtained in Catalyst Production Example 3-1 is placed in a tubular furnace, heated to 300 ° C. at a temperature rising rate of 10 ° C./min in an atmosphere of nitrogen gas containing 4% by volume of hydrogen gas, and held at 300 ° C. for 1 hour. A powdered catalyst was produced by natural cooling. The analysis was carried out to obtain a fuel cell electrode, and its oxygen reduction ability was evaluated. The results are shown in Table 4.

[Comparative Catalyst Production Example 3-9]
The powder obtained in Catalyst Production Example 3-1 is placed in a tubular furnace, heated to 1200 ° C. at a temperature rising rate of 200 ° C./h in an atmosphere of nitrogen gas containing 4% by volume of hydrogen gas, and held at 1200 ° C. for 2 hours. A powdered catalyst was produced by natural cooling. Furthermore, the electrode for fuel cells was obtained and the oxygen reduction ability was evaluated. The results are shown in Table 4.

[Comparative Catalyst Production Example 3-10]
The powder obtained in Catalyst Production Example 3-1 is placed in a tubular furnace, heated to 1400 ° C. at a temperature rising rate of 200 ° C./h in an atmosphere of nitrogen gas containing 4% by volume of hydrogen gas, and held at 1400 ° C. for 2 hours. A powdered catalyst was produced by natural cooling. Furthermore, the electrode for fuel cells was obtained and the oxygen reduction ability was evaluated. The results are shown in Table 4.

[Comparative Catalyst Production Example 3-11]
The powder obtained in Catalyst Production Example 3-1 is placed in a tubular furnace, heated to 1600 ° C. at a temperature rising rate of 200 ° C./h in an atmosphere of nitrogen gas containing 4% by volume of hydrogen gas, and held at 1600 ° C. for 2 hours. A powdered catalyst was produced by natural cooling. Furthermore, the electrode for fuel cells was obtained and the oxygen reduction ability was evaluated. The results are shown in Table 4.

※酸素還元電位Ｅ＠０．０５ｍＡ／ｃｍ²・・・酸素雰囲気での還元電流と窒素雰囲気での還元電流とに０．０５ｍＡ／ｃｍ²以上差が現れ始める電位

※ oxygen reduction potential E@0.05mA/cm ² ··· reduction current and reduction current and to 0.05mA / cm ² or more difference begins to appear potential in a nitrogen atmosphere in an oxygen atmosphere

表３、４中の略号の意味は以下のとおりである。

The meanings of the abbreviations in Tables 3 and 4 are as follows.

Acac: Acetylacetone Ti-iP: Titanium tetraisopropoxide TiAcac complex: Titanium tetraacetylacetonate Zr-B: Zirconium tetrabutoxide Ta-E: Tantalum pentaethoxide Nb-E: Niobium pentaethoxide V-iP: Vanadium oxytri Isopropoxide (VO (O-iPr) ₃ )
VAacac complex: vanadium acetylacetonate (V (acac) ₃ )

2 solid polymer electrolyte membrane, 5 anode side gas diffusion layer, 6 cathode side gas diffusion layer, 7, 8 separator plate, 7a, 8a gas flow path, 10 membrane / electrode assembly, 11 anode catalyst layer, 11a catalyst formation region 11b catalyst non-formation region, 12 cathode catalyst layer, 12a catalyst formation region, 12b catalyst non-formation region, 13 cathode catalyst layer, 13a first catalyst formation region, 13b second catalyst formation region, 13c catalyst non-formation region, 15 anode Catalyst paste, 16 Cathode catalyst paste, 20 First transfer film, 21 Second transfer film, 22 Third transfer film, 25, 26, 27 Laminate, 30 Upper mold, 30a Hot press surface, 30b Catalyst paste transfer part, 30c Concave groove (catalyst paste non-transfer part), 32 upper mold, 32a hot press surface, 32b catalyst pace Transfer portion, 32c recess (catalyst paste non-transfer portion), 33 upper mold, 33a hot press surface, 33b catalyst paste transfer portion, 33c recess (catalyst paste non-transfer portion).

Claims (6)

(A) Step a1 in which at least a transition metal-containing compound, a nitrogen-containing organic compound, and a solvent are mixed to obtain a catalyst precursor solution,
A step a2 of removing the solvent from the catalyst precursor solution, and a step a3 of obtaining a fuel cell electrode catalyst (a) by heat-treating the solid residue obtained in the step a2 at a temperature of 500 to 1100 ° C.,
A catalyst production process in which a part or all of the transition metal-containing compound is a compound containing at least one transition metal element M1 selected from Group 4 and Group 5 elements of the periodic table as a transition metal element;
(B) applying an anode catalyst paste onto the first transfer film;
(C) preparing a cathode catalyst paste containing the fuel cell electrode catalyst (a) and applying it on the second transfer film;
(D) The first and second transfer films are stacked so that the anode catalyst paste and the cathode catalyst paste are directed toward the solid polymer electrolyte membrane so as to sandwich the solid polymer electrolyte membrane, thereby forming a laminate. Process,
(E) Hot pressing the laminate using a mold having a hot press surface on which a flat catalyst paste transfer portion and a catalyst paste non-transfer portion having a predetermined depth with respect to the catalyst paste transfer portion are formed, A method for producing a membrane / electrode assembly, comprising: a hot pressing step of transferring the anode catalyst paste and the cathode catalyst paste onto the solid polymer electrolyte membrane in substantially the same shape as the catalyst paste transfer portion.   The method for producing a membrane-electrode assembly according to claim 1, wherein the first and second transfer films are formed to a thickness of 10 µm or more and 50 µm or less.   In the hot pressing step (E), the plurality of molds formed so that the catalyst paste transfer portions do not overlap with each other are hot pressed one by one, and the anode catalyst paste and the cathode catalyst paste are 2. The method for producing a membrane-electrode assembly according to claim 1, wherein the mold is transferred to the solid polymer electrolyte membrane in several times. The membrane / electrode assembly is produced by the production method according to claim 1 so that a non-catalyst forming region is formed in the anode catalyst layer and the cathode catalyst layer opposite to each other across the solid polymer electrolyte membrane. ,
An anode side gas diffusion layer and a cathode side gas diffusion layer are respectively disposed on the anode catalyst layer and the cathode catalyst layer to produce a membrane / electrode assembly with a gas diffusion layer,
A method for producing a polymer electrolyte fuel cell, comprising: laminating a plurality of membrane-electrode assemblies with a gas diffusion layer through a separator having a gas flow path formed therein.   5. The method for producing a polymer electrolyte fuel cell according to claim 4, wherein the anode catalyst layer and the cathode catalyst layer are composed of a plurality of catalyst formation regions separated by the catalyst non-formation region.   6. The catalyst layer according to claim 5, wherein at least one of the anode catalyst layer and the cathode catalyst layer is formed of catalyst pastes having different compositions, and at least two types of the catalyst formation regions are mixed. A method for producing the polymer electrolyte fuel cell as described.

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