JP2019153478A - Nanoparticle-bound catalyst and manufacturing method thereof, catalyst layer for gas diffusion electrode, membrane-electrode assembly, and fuel cell - Google Patents

Abstract

To provide: a method for manufacturing a nanoparticle-bound catalyst, which is superior in durability to a load response cycle; and the others.SOLUTION: A method for manufacturing a nanoparticle-bound catalyst according to the present invention comprises the steps of: forming a casting mold having a first polarity; forming a metal-based nanoparticle-attached casting mold having a second polarity on a casting mold surface; performing, on the metal-based nanoparticle-attached casting mold, either one of (I) a step of forming, by a heat treatment, a nanoparticle-bound skeleton comprising an alloy containing a first metal atom having a fuel cell catalytic activity and a second metal atom for enhancing the catalytic activity and, after coating at least part of a surface with a silica layer, increasing the degree of regularity of a regular atomic arrangement structure by a heat treatment, and (II) a step of forming, by a heat treatment, a nanoparticle-bound skeleton comprising the same constitution as in step (I) and increasing the degree of regularity of a regular atomic arrangement structure thereof after coating a surface with the silica layer; and removing the casting mold and the silica layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nanoparticle-linked catalyst and a method for producing the same. The present invention also relates to a gas diffusion electrode catalyst layer, a membrane electrode assembly, and a fuel cell using the nanoparticle-linked catalyst.

  Polymer electrolyte fuel cells (PEFC) attract attention from the viewpoint of high energy conversion efficiency and miniaturization. Fuel cell vehicles, stationary cone generation systems, portable power supplies, power supplies for information equipment Application to such as is expected. In order to improve the characteristics of the polymer electrolyte fuel cell, it is essential to improve the performance of the catalyst layer disposed on the electrodes (anode and cathode). For this reason, energetic research and development has been conducted on the catalyst layer, and many proposals have been made.

  Non-Patent Documents 1 and 2 report a catalyst in which platinum iron alloy and platinum cobalt alloy nanoparticles having an atomic arrangement ordered structure are supported on a carbon support. In Non-Patent Document 3, it has been reported that in a platinum iron alloy nanoparticle catalyst, the metal atomic arrangement ordered structure can be enhanced by performing heat treatment after coating with magnesium oxide. However, when carbon is used as the carrier, there is a problem that the carbon performance is significantly reduced due to corrosion of the carbon due to the start and stop of PEFC (Non-patent Document 4).

  The present inventors have recently developed a nanoparticle-linked catalyst in which metal-based nanoparticles are linked as a catalyst layer material for PEFC (Non-patent Document 5, Patent Document 1). This catalyst, for example in the form of a porous hollow capsule, forms a network structure in which metal catalysts are fused together, so that it can maintain a nano-sized crystallite diameter while having conductivity, and requires a carbon support. It has the feature of not. This catalyst revealed about 9 times higher ORR surface specific activity for oxygen reduction reaction (ORR) than the commercially available carbon-supported platinum nanoparticle catalyst. In addition, it was reported that it showed excellent durability in the start / stop durability test to accelerate carbon corrosion.

  Non-patent documents 6 and 7 report Pt nanochains, platinum-cobalt alloy nanowires and the like as carbon-free nanostructure catalysts.

Japanese Patent Laying-Open No. 2015-92464

J. Kim et al., J. Am. Chem. Soc., 2010, 132, 4996-4997, D. Wang et al., Nat. Mater., 2013, 12, 81-87 Q. Li et al., Nano letters, 2015, 15, 2468-2473. Y. Hashimasa et al., ECS Trans., 2012, 50, 723-732. T. Yamaguchi et al., Energy Environ. Sci., 8, 3545-3549 (2015). H. Wang et.al., Chem. Commun., 2011, 47, 3407-3409, S.M. Alia et al., ACS Catal., 2014, 4, 2680-2686

  For further diffusion of PEFC, it is indispensable to improve the performance and durability by improving the catalyst layer, particularly by improving the cathode catalyst layer in which the oxygen reduction reaction (ORR) occurs. By using the carbon support-free catalyst layer material for PEFC of Patent Document 1 described above, the durability could be significantly improved in the start / stop durability test for accelerating the carbon corrosion, but the load response for accelerating metal elution There is a strong demand for a technique for improving the durability in the durability test.

  The present invention has been made in view of the above background, and provides a nanoparticle-coupled catalyst excellent in durability against a load response cycle, a production method thereof, a catalyst layer for a gas diffusion electrode, a membrane electrode assembly, and a fuel cell. With the goal.

As a result of extensive studies by the present inventors, it has been found that the problems of the present invention can be solved in the following modes, and the present invention has been completed.
[1]: a step (a) of forming a template having a desired shape and having a first polarity;
A step of adsorbing metal-based nanoparticles containing catalyst nanoparticles having a second polarity opposite to the first polarity on the surface of the template, or growing them in situ to obtain a template with metal-based nanoparticles ( b) and
For the mold with metal nanoparticles,
(I) A nanoparticle-linked skeleton formed of an alloy of at least two kinds of metal atoms, ie, a first metal atom having fuel cell catalytic activity and a second metal atom that improves the catalytic activity of the first metal atom is formed by heat treatment. Then, after covering at least part of the surface with a silica layer, the step of increasing the degree of order of the atomic arrangement regular structure of the nanoparticle-linked skeleton by heat treatment, and (II) covering at least part of the surface with the silica layer Thereafter, a nanoparticle linking skeleton composed of an alloy of at least two kinds of metal atoms, ie, a first metal atom having fuel cell catalytic activity and a second metal atom that improves the catalytic activity of the first metal atom, is formed by heat treatment. And increasing the degree of order of the atomic arrangement regular structure of the nanoparticle-linked skeleton,
A step (c) of performing any one of
The manufacturing method of the nanoparticle connection catalyst which comprises the process (d) which removes the said casting_mold | template and the said silica layer after a process (c).
[2] The method for producing a nanoparticle-linked catalyst according to [1], wherein the nanoparticle-linked catalyst is at least one of a capsule shape, a rod shape, and a sheet shape.
[3]: The method for producing a nanoparticle-linked catalyst according to [1] or [2], wherein the step (d) is 500 ° C. to 1300 ° C.
[4]: The nanoparticle-linked skeleton is an alloy containing two or more kinds selected from platinum, iron, cobalt, nickel, palladium, silver, gold, copper, ruthenium, iridium, molybdenum, rhodium, chromium, tungsten, and manganese. The manufacturing method of the nanoparticle connection catalyst in any one of [1]-[3] which consists of.
[5]: Any one of [1] to [4], in which the processing conditions of the step (d) are adjusted so that atoms located in the surface layer of the nanoparticle-linked skeleton are mainly formed from the first metal atoms. The manufacturing method of the nanoparticle connection catalyst as described in any one of.
[6] A nanoparticle-linked catalyst obtained by the method for producing a nanoparticle-linked catalyst according to any one of [1] to [5].
[7]: A first metal atom which is made of a sintered body and has nanoparticles connected to each other and has a fuel cell catalytic activity, and a metal of a different type from the first metal atom. A nanoparticle-coupled catalyst having an atomic arrangement regular structure composed of at least two kinds of alloys of second metal atoms to be improved and having a nanoparticle-linked skeleton having a degree of order of the atomic arrangement regular structure of 0.5 or more .
[8] The nanoparticle-linked catalyst according to [7], which is at least one of a capsule-shaped catalyst, a rod-shaped catalyst, and a sheet-shaped catalyst.
[9]: The nanoparticle coupling skeleton is selected from platinum, iron, cobalt, nickel, palladium, silver, gold, copper, ruthenium, iridium, molybdenum, rhodium, chromium, tungsten, and manganese. The nanoparticle-linked catalyst according to [7] or [8], which comprises an alloy containing two or more types.
[10] The nanoparticle-linked catalyst according to any one of [7] to [9],
A catalyst layer for a gas diffusion electrode comprising the nanoparticle-coupled catalyst and an ionic conductor that is at least partially in contact.
[11] A membrane electrode assembly in which a solid polymer electrolyte membrane is disposed between an anode catalyst layer and a cathode catalyst layer,
A membrane / electrode assembly using the gas diffusion electrode catalyst layer according to [10] as at least one of the anode catalyst layer and the cathode catalyst layer.
[12]: A fuel cell comprising the membrane electrode assembly according to [11].

  According to the present invention, it is possible to provide a nanoparticle-coupled catalyst having excellent durability against a load response cycle, a method for producing the catalyst, a gas diffusion electrode catalyst layer, a membrane electrode assembly, and a fuel cell.

The schematic diagram which shows an example of the nanoparticle connection catalyst which concerns on 1st Embodiment. Explanatory drawing which shows an example of the manufacturing process of the nanoparticle connection catalyst which concerns on 1st Embodiment. Explanatory drawing which shows an example of the manufacturing process of the nanoparticle connection catalyst which concerns on 1st Embodiment. 1 is a schematic cross-sectional view showing an example of a main part of a polymer electrolyte fuel cell according to a first embodiment. The typical partial enlarged view of the catalyst layer for gas diffusion electrodes which concerns on 1st Embodiment. The typical partial enlarged view of the catalyst layer for gas diffusion electrodes which concerns on 3rd Embodiment. The typical explanatory view of MEA concerning a 3rd embodiment. The typical explanatory view of the catalyst layer for gas diffusion electrodes concerning a 4th embodiment. 2 is a transmission electron microscope image of the silica-coated particles of Example 1. FIG. The transmission electron microscope image of the nanoparticle connection catalyst of Examples 1-3 and the comparative example 1. FIG. The transmission electron microscope image of the nanoparticle connection catalyst of Example 5. FIG. The transmission electron microscope image of the nanoparticle connection catalyst of the comparative example 2. The figure which shows the XRD measurement result of the powder sample of Examples 1-3 and the comparative example 1. The figure which shows the XRD measurement result of the powder sample of Example 5 and Comparative Example 1. The CV curve of the electrode of Example 1,2. The CV curve of the electrode of Example 4 and Comparative Example 1. The CV curve of the electrode of Example 5 and Comparative Example 1. The LSV curve of the electrode of Example 1,2. The LSV curve of the electrode of Example 4 and the comparative example 1. FIG. The LSV curve of the electrode of Example 5 and Comparative Example 1. Explanatory drawing of the FCCJ protocol applied to the durability test. The figure which compared the CV curve before and behind the durability test in the electrode of Example 2. FIG. The figure which compared the LSV curve before and behind the durability test in the electrode of Example 2. FIG. The figure which compared the CV curve before and behind the durability test in the electrode of Example 4. FIG. The figure which compared the LSV curve before and behind the durability test in the electrode of Example 4. FIG. The figure which plotted mass activity with respect to the frequency | count of a durability test of the sample produced using Examples 2 and 4 and Comparative Examples 1 and 3. FIG. The figure which plotted ORR surface specific activity with respect to the durability test frequency | count of the sample produced using Examples 2 and 4 and Comparative Examples 1 and 3. FIG. The figure which shows ORR surface specific activity with respect to the frequency | count of a durability test of the sample created using Example 2, 4 and the comparative example 1 (normalized with respect to an initial value). EDX line mapping of the sample of Example 2. EDX line mapping of the sample of Example 4. The EDX line mapping of the sample of the comparative example 1. The graph which compared the initial mass activity of the electrode using the sample of Example 2, 4 and Comparative Example 1, 3, and the mass activity after 10,000 cycles. The graph which compared the initial ORR surface specific activity of the electrode using the sample of Example 2, 4 and Comparative Example 1, 3, and the ORR surface specific activity after 10,000 cycles.

  Hereinafter, an example of an embodiment to which the present invention is applied will be described. In addition, the numerical value specified in this specification is a value calculated | required by the method disclosed by embodiment or an Example. In order to clarify the explanation, the following description and drawings are simplified as appropriate. Further, matters necessary for carrying out the present invention that are not particularly mentioned in the present specification can be grasped as design matters of those skilled in the art based on the prior art in this field. Hereinafter, embodiments of the present invention applied to a polymer electrolyte fuel cell will be described with reference to a nanoparticle-linked catalyst and a production method thereof according to the present invention.

[First Embodiment]
The manufacturing method of the nanoparticle connection catalyst which concerns on 1st Embodiment has the following processes at least. That is,
Step (a): forming a template having a desired shape and having a first polarity;
Step (b): a step of adsorbing metal nanoparticles having a second polarity opposite to the first polarity on the surface of the template, or growing the nanoparticles in situ to obtain a template with metal nanoparticles.
Step (c): For the template with metal nanoparticles,
(I) A nanoparticle-linked skeleton formed of an alloy of at least two kinds of metal atoms, ie, a first metal atom having fuel cell catalytic activity and a second metal atom that improves the catalytic activity of the first metal atom is formed by heat treatment. Then, after covering at least part of the surface with a silica layer, the step of increasing the degree of order of the atomic arrangement regular structure of the nanoparticle-linked skeleton by heat treatment, and (II) covering at least part of the surface with the silica layer Thereafter, a nanoparticle linking skeleton composed of an alloy of at least two kinds of metal atoms, ie, a first metal atom having fuel cell catalytic activity and a second metal atom that improves the catalytic activity of the first metal atom, is formed by heat treatment. And increasing the degree of order of the atomic arrangement regular structure of the nanoparticle-linked skeleton,
A process of performing any one of
Step (d): After the step (c), there is a step of removing the template and the silica layer.

The nanoparticle-coupled catalyst according to the first embodiment is a first metal atom having fuel cell catalytic activity and a metal species different from the first metal atom, and improves the catalytic activity of the first metal atom. It consists of at least two kinds of alloys of two metal atoms, and consists of a nanoparticle-linked skeleton having an atomic arrangement regular structure. Here, the atomic arrangement regular structure is referred to as a crystal lattice representing a three-dimensional arrangement of particles regularly arranged in a crystal, and is also referred to as a superlattice structure. For example, L1 ₀ type fct structure and L1 ₂ type fcc structure can be exemplified (RSC Adv., See 2016,6,3307-3325).

  In FIG. 1, the schematic diagram of an example of a nanoparticle connection catalyst is shown. The nanoparticle-linked catalyst according to the first embodiment includes a capsule catalyst 30. As shown in FIG. 1, the outer shell forms a substantially spherical nanoparticle-linked skeleton 31, and the inside has a hollow structure. The nanoparticle connection skeleton 31 has a network structure in which metals are fused together, and has electronic conductivity.

  Numerous voids 33 are formed in the nanoparticle linking skeleton 31. The gap 33 is formed so as to communicate the inside and the outside of the capsule catalyst 30 that defines the contour. The porosity of the nanoparticle connection skeleton 31 is not particularly limited. The nanoparticle linking skeleton 31 may be maintained within a range where electron conductivity can be secured, and can be appropriately designed according to the application and required needs. In applications where the amount of catalyst is required, for example, the voids can be about 1%. In addition, when the strength of the nanoparticle linking skeleton 31 is high due to the structure, for example, the voids can be about 90%.

  The thickness of the outer shell of the capsule catalyst 30 is not particularly limited, but is preferably 2 nm or more and 50 nm or less. By making the thickness of the capsule-shaped catalyst 30 2 nm or more, it is possible to suppress the structural defects and perform stable production. In addition, the shape of the nanoparticle connection catalyst 3 is not particularly limited, and the shape can be freely designed by controlling the shape of the template particles described later. For example, an elliptical sphere shape, a cylindrical rod shape as in a third embodiment to be described later, a sheet shape as in the fourth embodiment, or a spiral shape can be used. Moreover, even if it comprises from a single type, you may comprise by uniting two or more types.

  The nanoparticle connection skeleton 31 is made of an alloy containing two or more kinds selected from platinum, iron, cobalt, nickel, palladium, silver, gold, copper, ruthenium, iridium, molybdenum, rhodium, chromium, tungsten, and manganese. As the first metal atom, platinum, iridium, ruthenium, and palladium are preferable. Of these, platinum is particularly preferred. As the second metal atom, platinum, cobalt, nickel, palladium, iron, silver, gold, copper, ruthenium, iridium, molybdenum, rhodium, chromium, tungsten, and manganese are preferable. Of these, iron, cobalt, nickel, and copper are particularly preferable. Preferred examples of the alloy include platinum alloys such as platinum-iron alloy, platinum-cobalt alloy, platinum-copper alloy, platinum-iron-cobalt alloy, platinum-iron-nickel, platinum-iron-copper. In these platinum alloy examples, platinum is the first metal atom, and the other metal is the second metal atom.

  By using an alloy containing the second metal atom, the bond distance and electronic state of the first metal atom layer of the nanoparticle-linked catalyst can be changed, thereby improving the catalytic activity of the first metal. Examples of a suitable atomic arrangement regular structure of the nanoparticle linking skeleton include a superlattice structure such as an fcc ordered structure and an fct ordered structure.

  The particle size of the capsule-shaped catalyst 30 is not particularly limited, and can be appropriately selected according to the application. The particle size of the capsule-shaped catalyst 30 can be easily controlled by controlling the size of the template particles described later. Considering the size of the pre-template particles described later, the particle size of the capsule catalyst 30 is usually 10 nm or more. In the gas diffusion electrode catalyst layer 2, a plurality of particles having different particle diameters may be mixed.

  Hereinafter, steps (a) to (d) will be described in detail with reference to FIGS. 2 and 3. In addition, the same code | symbol is attached | subjected to the same element member in the following drawings.

[Step (a)]
First, an aqueous dispersion of pre-template particles (not shown) is prepared. Suitable materials for the pre-template particles include silica (SiO ₂ ), titanium oxide (TiO ₂ ), magnesium fluoride (MgF ₂ ), aluminum fluoride (AlF ₃ ), lithium fluoride (LiF), sodium fluoride ( NaF), aluminum oxide (Al ₂ O ₃ ), zirconia oxide (ZrO ₂ ), niobium oxide (Nb ₂ O ₅ ), indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO ₂ ), ceria Examples thereof include inorganic materials such as (CeO ₂ ), yttrium oxide (Y ₂ O ₃ ), bismuth oxide (Bi ₂ O ₃ ), apatite, and glass. The pre-template particles may be made of a single material or may be particles in which a plurality of materials are mixed. Moreover, the particle | grains which knead | mixed and mixed two or more types of materials previously, and granulated and classified may be sufficient.

  The preparation method of the pre-molded particles is not particularly limited. For example, rolling granulation, fluidized bed granulation, stirring granulation, crushing / pulverization granulation, compression granulation, extrusion granulation, fusion granulation, mixed granulation Granulation can be performed using physical granulation methods such as granulation, spray-cooling granulation, spray-drying granulation, precipitation / precipitation granulation, freeze-drying granulation, suspension aggregation granulation, and drop-cooling granulation. Classify as necessary. If pre-molded particles are available as commercial products, they may be used.

  The range of the particle size of the pre-template particles is not particularly limited, but is usually about 10 nm to 10 μm. If the particle size exceeds 10 μm, the pre-template particles may not be dispersed in the solvent. In addition, the shape of the pre-template particles is not particularly limited, but is usually spherical or approximately spherical. The shape of the hollow capsule catalyst 30 can be adjusted by the shape of the pre-template particles as described above.

  Next, an aqueous dispersion of the template particle 35 (see FIG. 2A) in which the surface of the pre-template particle is coated with the coating layer having the first polarity is prepared. Since the template particle 35 is coated with the coating layer, the particle diameter is larger than that of the pre-template particle. The thickness of the coating layer is not particularly limited, and can be set as appropriate without departing from the spirit of the present invention. The coating layer does not necessarily have to be coated over the entire surface of the pre-template particles, and there may be uncoated areas.

  The method of coating the coating layer on the pre-template particles is not particularly limited, but a method of coating by electrostatic coupling is simple. When the pre-template particles are negatively charged particles, a positively charged coating layer can be coated. In addition, when the pre-template particles are positively charged particles, a negatively charged coating layer can be coated. It is also possible to coat the negatively charged coating layer with a positively charged coating layer.

  The coating layer is not particularly limited as long as the template particle 35 can express the first polarity, and examples thereof include ionic polymers (cationic polymers and anionic polymers). Examples of the ionic polymer include polymers having a charged functional group in the main chain or side chain. Examples of the ionic polymer having a positive charge generally include those having a positive charge such as a quaternary ammonium group or an amino group or having a functional group capable of being charged. Specific examples include polyethyleneimine (PEI), polyallylamine hydrochloride (PAH), polydiallyldimethylammonium chloride (PDDA), polyvinylpyridine (PVP), and polylysine. On the other hand, examples of the ionic polymer having a negative charge generally include those having a negative charge or a functional group capable of being charged, such as sulfonic acid, sulfuric acid, and carboxylic acid. Specific examples include polystyrene sulfonic acid (PSS), polyvinyl sulfate (PVS), dextran sulfate, chondroitin sulfate, polyacrylic acid (PAA), polymethacrylic acid (PMA), polymaleic acid, and polyfumaric acid. Through these steps, the template of step (a) is formed.

  The zeta potential of the obtained aqueous dispersion is preferably +5 mV or more when the first polarity is positive. If it is less than +5 mV, the template particles 35 may aggregate and settle in water. Although an upper limit is not specifically limited, Usually, it is +80 mV or less. On the other hand, when the first polarity is negative, it is preferably −5 mV or less for the same reason as described above. Moreover, although a minimum is not specifically limited, Usually, it is -80 mV or more.

[Step (b)]
Next, in order to form the nanoparticle connection skeleton 31 that forms the skeleton of the capsule-shaped catalyst 30 on the surface of the template particle 35, a metal nanoparticle material is adsorbed or grown in situ. Thereby, the template particle | grains to which the metal type nanoparticle 36 (The precursor of a catalyst particle may be included) (refer FIG.2 (b)) adhered is obtained. Specifically, a solution in which a material for forming the capsule catalyst 30 is dissolved in a uniform dispersion of the template particles 35 is added, and these are adsorbed on the template particles 35 or grown in situ. As the metal-based nanoparticles, those having a second polarity having a polarity opposite to the first polarity of the surface of the template particle 35 are used.

  The shape of the metal-based nanoparticles is not particularly limited, and an amorphous powder, a flat powder, a spherical powder, a rod-shaped powder, and the like can be appropriately selected according to the use and purpose. When the metal-based nanoparticles are a blend, a plurality of shapes may be mixed. In addition, the metal-based nanoparticles may contain a component to be removed in the heating step described later.

  The average particle diameter of the metal-based nanoparticles is not particularly limited, but is preferably 1 nm or more, and is preferably 50 nm or less from the viewpoint of improving the specific surface area or catalyst activity per mass. The average particle diameter of the metal-based nanoparticles is more preferably 25 nm or less, and particularly preferably 15 nm or less, from the viewpoint of improving the specific surface area or catalytic activity per mass. A material having high catalytic ability even if the particle diameter of the catalyst nanoparticles is small is preferable. As a preferable material of the catalyst nanoparticles, the material of the capsule catalyst 30 described above can be exemplified. The preferable range of the average particle diameter of the metal-based nanoparticles other than the catalyst nanoparticles is also the same.

[Step (c)]
Subsequently, for the metal nanoparticle-attached template obtained in the step (b),
(I) A first metal atom having fuel cell catalytic activity and an alloy of at least two types of second metal atoms that are different from the first metal atom and improve the catalytic activity of the first metal atom Heat treatment for forming a nanoparticle-linked skeleton comprising, and then coating at least a part of the surface with a silica layer, followed by heat treatment to increase the degree of order of the atomic arrangement regular structure of the nanoparticle-linked skeleton. And (II) after coating at least a part of the surface with the silica layer, the first metal atom having the fuel cell catalytic activity and a metal species of a different type from the first metal atom, and the first metal Heating to form a nanoparticle-linked skeleton composed of at least two types of alloys of second metal atoms that improve the catalytic activity of the atoms and to increase the degree of order of the atomic arrangement regular structure of the nanoparticle-linked skeleton Step of performing a physical,
Do either one.

  FIG. 2 illustrates the case of step (I). In the case of (I), in the step (c), first, heat treatment (sintering treatment) is performed (see FIG. 2C). Thereby, the adhered metal-based nanoparticles 36 are converted into a sintered body, and the nanoparticle-linked skeleton 31 is obtained. Examples of the method for obtaining a sintered body include hydrothermal reaction and alcohol thermal reaction.

  The method of the heat treatment (sintering treatment) is not particularly limited as long as a metal network structure can be formed, but it is preferably performed by a hydrothermal reaction or an alcohol thermal reaction. The hydrothermal reaction and alcohol thermal reaction are preferably in a subcritical state, and particularly preferably in a supercritical state. The conditions for the hydrothermal reaction in subcritical or supercritical water are not particularly limited. It depends on the type and size of the template material and the coverage of the nanoparticles in the metal-based nanoparticles 36. In the case of silica fine particles having a particle size of about 300 nm, for example, 330 ° C., 20 MPa, reaction time of 3 hours, etc. can be used. Examples of a method for forming a superlattice structure include a method in which iron is contained in catalyst nanoparticles and an alcohol thermal reaction is performed.

  In the case of (I), the silica coating is performed after the heat treatment (sintering treatment) (see FIG. 2D). The silica coating method is not particularly limited as long as the nanoparticle-linked skeleton obtained by heat treatment (sintering treatment) can be coated with the silica layer. For example, a method of obtaining the obtained nanoparticle-linked skeleton by stirring tetraethyl orthosilicate as a silica source in ammonia water for several hours at room temperature can be exemplified. As the silica source, 3-aminopropyltriethoxysilane or methyltriethoxysilane may be used. It can also be obtained by stirring the silica source in an aqueous basic amino acid solution such as lysine or arginine. Although the thickness of a silica layer is not specifically limited, For example, it is about 1-100 nm.

Thereafter, heat treatment is performed to increase the degree of order of the atomic arrangement regular structure of the obtained nanoparticle-linked skeleton. By covering the silica layer 37, the metal catalyst of the nanoparticle-linked skeleton is prevented from fusing with each other during the heat treatment, and the atomic arrangement ordered structure is maintained while maintaining the nanoparticle-linked skeleton that is a metal-based network structure. Can increase the degree of order. The heat treatment is not particularly limited as long as the degree of order of the atomic arrangement regular structure can be increased. For example, the heat treatment is performed at 500 to 1300 ° C. for about 30 minutes to about 10 hours in an H ₂ / N ₂ atmosphere or an inert gas atmosphere. More preferably, it is 600-1100 degreeC, More preferably, it is 700-900 degreeC. In the step (c), by forming the silica layer 37, the aggregation during the heat treatment for increasing the degree of order is suppressed, and the degree of order of the atomic arrangement ordered structure is increased while maintaining the linked skeleton of the nanoparticles. It becomes possible.

  FIG. 3 is a schematic diagram for explaining the case of step (c) (II). In the case of (II), silica coating is first performed (see FIG. 3A). Thereafter, a first metal atom having fuel cell catalytic activity and a metal species of a different type from the first metal atom, and at least two alloys of a second metal atom that improve the catalytic activity of the first metal atom A heat treatment is performed to form a nanoparticle-linked skeleton composed of the above and to increase the degree of order of the atomic arrangement regular structure of the nanoparticle-linked skeleton (see FIG. 3B). By performing the heat treatment after the formation of the silica layer 37 in this manner, aggregation of the attached metal nanoparticles 36 can be effectively prevented.

  The heat treatment method is not particularly limited as long as a metal-based network structure can be formed and the degree of order of the atomic arrangement regular structure of the nanoparticle-linked skeleton can be increased. The heat treatment condition can be performed under one heat treatment condition or a plurality of conditions. For example, optimal heat treatment can be performed in order to form a nanoparticle-linked skeleton, and then optimal heat treatment can be performed in two or more stages in order to increase the degree of order of the atomic arrangement regular structure.

By forming the silica layer 37 in advance, aggregation of metal nanoparticles can be effectively suppressed, so that it is easy to form a nanoparticle-linked skeleton even in a method of heat treatment at normal pressure. Of course, as in (I), heat treatment can be performed in a subcritical or supercritical state. The heat treatment is not particularly limited as long as the degree of order of the atomic arrangement regular structure can be increased. For example, the heat treatment is performed at 500 to 1300 ° C. for about 30 minutes to about 10 hours in an H ₂ / N ₂ atmosphere or an inert gas atmosphere. The heating temperature is more preferably 600 to 1100 ° C, still more preferably 700 to 900 ° C. By forming the silica layer 37 in advance, it is possible to suppress the aggregation during the heat treatment and to increase the degree of order of the atomic arrangement regular structure while maintaining the connecting skeleton of the nanoparticles. The range of the degree of order can vary depending on the type of alloy of the obtained nanoparticle-coupled catalyst, and is not limited to a specific numerical range.

[Step (d)]
After the step (c), the silica layer 37 and the template particles 35 are eluted. Thereby, a hollow capsule-shaped catalyst 30 as shown in FIG. 2 (e) is obtained. The elution treatment method is not particularly limited as long as the object can be achieved, and examples thereof include a method of removing the silica layer 37 and the template particles 35 by alkali treatment such as NaOH aqueous solution.

  As a result of extensive studies by the present inventors, it has been found that the oxygen reduction characteristics fluctuate when used as a catalyst for a fuel cell due to the structure of the surface layer of the nanoparticle-linked skeleton. In other words, it was found that appropriately controlling the surface structure of the nanoparticle-linked catalyst is important for improving the activity. Specifically, it was found that oxygen reduction characteristics can be enhanced by forming atoms (one to several layers) located on the surface layer of the nanoparticle-linked skeleton mainly from the first metal atoms. The state of atoms located on the surface layer of the first metal can be easily adjusted by changing conditions such as the concentration and time of the alkali treatment when the alkali treatment is performed in the step (d).

  It was also found that the ORR mass activity and the ORR surface specific activity of the nanoparticle-linked skeleton differ depending on the processing conditions when removing the template particles 35 and the silica layer 37 in the step (d). For example, if an alkali treatment is used in the step (d), an alkali treatment (e.g., treatment with an aqueous NaOH solution of 1M or more and 5M or less, etc.) under mild conditions can be performed by a rich layer of the first metal atom on the surface layer. Shows high ORR activity. On the other hand, when treated under strong alkaline conditions (for example, when treated with an aqueous NaOH solution of 5M or more, 12M or less, etc.), the ORR activity is lower in the first metal atom rich layer than the mild alkali treatment. Indicates.

  The capsule-shaped catalyst 30 as shown in FIG. 1 is obtained by the above process. The capsule catalyst 30 is used as the nanoparticle-linked catalyst 3 that is in contact with and / or fused with each other.

  According to the method for producing a nanoparticle-coupled catalyst of the first embodiment, when a capsule-shaped catalyst as shown in FIG. 1 is produced, the metal catalyst is melted by a simple method of coating with a silica layer and heat-treating. The degree of ordering of the metal atomic arrangement ordered structure can be increased while preventing adhesion and maintaining the intermetallic network structure. Moreover, the surface area which can be utilized as a catalyst can be raised by using the capsule-shaped catalyst 30 which connected the nanoparticle and networked.

  The nanoparticle-linked catalyst of the first embodiment forms a gas diffusion electrode layer together with an ionic conductor, and can be suitably applied as a catalyst for a fuel cell or the like. Hereinafter, the example which applied the nanoparticle connection catalyst which concerns on 1st Embodiment to the polymer electrolyte fuel cell is demonstrated.

[Fuel cell]
FIG. 4 is a schematic cross-sectional view showing an example of a main part of the polymer electrolyte fuel cell according to the first embodiment. The polymer electrolyte fuel cell 1 includes a polymer electrolyte membrane 5 having ion conductivity, an anode unit 10 to which a fuel gas such as hydrogen is supplied, and a cell 6 having a cathode unit 20 to which oxygen is supplied, and an outside. Circuit 7 and the like. Normally, a battery is configured by stacking cells 6 according to a required output.

  In the anode unit 10, an anode catalyst layer 11, a gas diffusion layer 12, and a separator 13 are arranged in this order from the solid polymer electrolyte membrane (hereinafter referred to as polymer electrolyte membrane) 5 side, and the cathode unit 20 includes a cathode catalyst layer 21, a gas The diffusion layer 22 and the separator 23 are arranged in this order from the polymer electrolyte membrane 5 side. Here, an electrode with which a gas, an electrolyte, and a catalyst layer can simultaneously contact is referred to as a gas diffusion electrode. In the first embodiment, the anode catalyst layer 11 and the gas diffusion layer 12, and the cathode catalyst layer 21 and the gas diffusion layer 22 are gas diffusion electrodes, respectively. However, as described above, the gas diffusion electrode only needs to be able to contact the gas, the electrolyte, and the catalyst layer at the same time, and the gas diffusion layers 12 and 22 are not necessarily used. In other words, the gas diffusion electrode catalyst layer can be composed of only the anode catalyst layer 11 and / or the cathode catalyst layer 21. A structure in which each catalyst layer of the pair of gas diffusion electrodes is bonded to the electrolyte membrane so as to face the electrolyte membrane is referred to as a membrane electrode assembly (MEA) 8. The external circuit 7 is electrically connected to the anode catalyst layer 11 of the anode unit 10, the cathode catalyst layer 21 of the cathode unit 20, and the like.

  In the polymer electrolyte fuel cell 1 configured as described above, a reducing gas such as hydrogen is supplied from the gas flow path 14 of the separator 13 to the anode catalyst layer 11 through the gas diffusion layer 12 in the anode unit 10. The On the other hand, in the cathode unit 20, an oxidizing gas such as oxygen or air is supplied from the gas flow path 24 of the separator 23 to the cathode catalyst layer 21 through the gas diffusion layer 22.

  In the case of the cation exchange type using hydrogen gas as the reducing gas and oxygen gas as the oxidizing gas, an oxidation reaction of hydrogen occurs in the anode catalyst layer 11 to generate hydrogen ions and electrons. The generated hydrogen ions move to the cathode catalyst layer 21 through the polymer electrolyte membrane 5 having ion conductivity. On the other hand, the generated electrons move to the cathode catalyst layer 21 via the external circuit 7. Hydrogen ions and electrons that have reached the cathode unit 20 react with oxygen in the cathode catalyst layer 21 to generate water. That is, in the cathode catalyst layer 21, a reduction reaction of oxygen occurs. The water generated by the reduction reaction is discharged to the outside from the gas diffusion layer 22 of the cathode unit 20 or supplied to the polymer electrolyte membrane 5. Electricity is supplied to the outside by a series of these reactions.

  The polymer electrolyte membrane 5 is not particularly limited as long as it is a membrane made of a material that can transport ions and does not exhibit electronic conductivity. Preferable examples include polyperfluorosulfonic acid resin, sulfonated polyether sulfonic acid resin, sulfonated polyimide resin, and sulfuric acid doped polybenzimidazole.

  Hereinafter, the gas diffusion electrode catalyst layers used as the anode catalyst layer 11 and the cathode catalyst layer 21 will be described in detail. Note that the gas diffusion electrode catalyst layer described in detail below is not necessarily used for both the anode catalyst layer 11 and the cathode catalyst layer 21, but may be used for at least one of them.

  FIG. 5 is a schematic partial enlarged view of the gas diffusion electrode catalyst layer according to the first embodiment. The catalyst layer 2 for gas diffusion electrode includes a nanoparticle-coupled catalyst 3 and an ion conductor 4 that is at least partially in contact with the nanoparticle-coupled catalyst 3. The nanoparticle-linked catalyst 3 according to the first embodiment is composed of a capsule-shaped catalyst 30 having a metal nanoparticle-linked skeleton. The capsule-shaped catalyst 30 is in contact with the ion conductor 4 mainly on the outer surface. The capsule catalysts 30 are brought into contact with and / or fused together to ensure electronic conductivity. However, in the example of FIG. 5, for convenience of explanation, the capsule catalysts 30 arranged on one surface are illustrated. In the drawings, some of the capsule catalysts 30 are not joined and / or fused.

  The thickness of the catalyst layer 2 for gas diffusion electrode can be appropriately designed according to the use, but it is preferably thin from the viewpoint of improving the efficiency of gas diffusion. Gas diffusion electrode of various fuel cells such as direct methanol type liquid fuel type fuel cell and gas fuel type fuel cell such as hydrogen / oxygen fuel cell, which may vary depending on the type of fuel cell and the type of catalyst used The thickness of the catalyst layer is preferably 10 μm or less. Particularly in a hydrogen / oxygen fuel cell or the like, the thickness of the gas diffusion electrode catalyst layer is preferably 2 μm or less, and more preferably 0.5 μm or less, from the viewpoint of enhancing gas diffusivity with higher efficiency.

  The ion conductor 4 should just show ionic conductivity, and a conventionally well-known thing can be used for it. In the case of a cation conductor, a proton conductor that conducts hydrogen ions is usually used, and in the case of an anion conductor, a hydroxide ion conductor that conducts hydroxide ions is usually selected. As the ion conductor 4, a resin having an ion conductive group can be suitably used. For example, a polymer obtained by introducing a sulfonic acid group or an anion exchange group into a fluorocarbon or hydrocarbon polymer, an inorganic proton conductor such as a zirconium compound having an acidic functional group, an inorganic anion conductor such as a layered double hydroxide, etc. It can be illustrated. Examples of acidic functional groups include sulfonic acid groups, sulfo groups, sulfonyl groups, and phosphoric acid groups. Examples of zirconium compounds include zirconium sulfate, zirconium zirconium sulfophenylphosphonate, zirconium phosphate, and zirconia sulfate. . Examples of the polymer having a sulfonic acid group include perfluorosulfonic acid polymers (Nafion (registered trademark), Flemion (registered trademark), Aciplex (trade name), etc.), SPES: polyethersulfone, SPEEK: sulfonated polyether. Examples include ether ketone and SPEK: sulfonated polyether ketone.

  The content of the ion conductor 4 in the gas diffusion electrode catalyst layer 2 is not particularly limited as long as the ion conductivity can be secured and the electric resistance value does not become too large. The gas diffusion electrode catalyst layer 2 may contain other components such as a binder other than the ion conductor 4.

  The capsule catalyst 30 has electronic conductivity because the metals are fused to each other on the capsule surface. The electronic conductivity between the capsule and the other capsules is as follows: (1) a method of ensuring electronic conductivity by bringing the capsule-shaped catalysts 30 into contact with each other; (2) fusion of the capsule-shaped catalysts 30 to each other between the particles. Examples of such a connection method and / or (3) a method of adding another conductive particle in order to assist the conductivity between the particles of the encapsulated catalyst 30 can be exemplified. Examples of the method (1) include a method of applying an appropriate pressure from above and below in the thickness direction when forming a membrane electrode assembly. It is preferable to hot press at an appropriate temperature. Examples of the method (2) include a method of forming a desired shape during the sintering process described later, and a method in which particles of the capsule catalyst 30 are fused at the stage of forming a sintered body. An example is a method in which the treatment is performed in contact. Examples of the method (3) include a method of adding conductive particles such as conductive carbon. In this case, it is preferable to select particles having an appropriate particle size so as not to inhibit gas diffusion. Examples thereof include particles having a particle size smaller than that of the capsule catalyst 30 and porous carbon particles having excellent gas flowability. Said (1)-(3) can be used individually or in combination. In addition, according to the nanoparticle-coupled catalyst obtained by the production method of the first embodiment, durability against a load response cycle when used for a gas diffusion electrode layer of a fuel cell can be significantly improved.

<Manufacture of gas diffusion electrode catalyst layer>
The gas diffusion electrode catalyst layer according to the first embodiment is manufactured through the following steps. However, the manufacturing method of the gas diffusion electrode catalyst layer of the present invention is not limited to the following manufacturing method.

The step of incorporating the ion conductor into the catalyst layer so as to have a contact site with the nanoparticle-coupled catalyst. This ionic conductor is at least one of the following (i) to (iii).
(I) Components contained in the template incorporated by step (a).
(Ii) A component obtained by converting the component contained in the template as a precursor.
(Iii) A component to be introduced by newly adding after step (d).

  It incorporates in the obtained nanoparticle connection catalyst so that at least one part of an ion conductor may have a contact part. As the ion conductor, inorganic particles as described above, ion conductive binders such as polymers, or composite materials thereof are preferably used. Examples of the incorporation method include a method in which the ion conductor 4 is added to the nanoparticle-coupled catalyst 3 and kneading, and a method in which the ion conductor 4 is heated and melted and entangled with the nanoparticle-coupled catalyst 3. In addition, it is not limited to the case where it implements after process (d), The method of incorporating by the method of above-mentioned (i) and (ii), and the method of using together (i)-(iii) arbitrarily can be illustrated.

  According to the PEFC of the first embodiment, it is possible to provide a nanoparticle-linked catalyst that achieves both excellent load response durability and high ORR activity. According to the gas diffusion electrode catalyst layer 2 of the first embodiment, it is possible to achieve both excellent load response durability and high ORR activity by increasing the degree of order of the atomic arrangement regular structure of the nanoparticle coupled catalyst. Moreover, the surface area which can be utilized as a catalyst can be raised by using the capsule-shaped catalyst 30 which connected the nanoparticle and networked. Further, by making the carbon carrier, which is the main factor of thickness, free, the thickness of the catalyst layer can be reduced. As a result, the gas diffusion distance can be reduced and the gas diffusion rate can be increased, so that the problem of gas diffusion rate control, which has been a problem in the high current density region of the catalyst layer using the conventional carbon support, is solved. High output can be realized. In addition, since it is not affected by carbon corrosion, the start / stop cycle can be improved.

[Second Embodiment]
The nanoparticle-coupled catalyst according to the second embodiment is formed of a sintered body, and is composed of a first metal atom having a fuel cell catalyst activity by linking the nanoparticles and a metal of a different type from the first metal atom. Electron conduction having an atomic arrangement ordered structure composed of at least two kinds of alloys of second metal atoms that improve the catalytic activity of one metal atom, and having a nanoparticle-linked skeleton in which the degree of order of the atomic arrangement ordered structure is 0.5 or more It is a catalyst which shows the property.

  As described in the first embodiment, the range of the degree of order can vary depending on the type of alloy of the obtained nanoparticle-coupled catalyst, and is not limited to a specific numerical range, but the degree of order is 0.5. By setting it as the above, the more outstanding catalyst characteristic is acquired. The nanoparticle coupled catalyst according to the second embodiment can be obtained by the method for producing a nanoparticle coupled catalyst according to the first embodiment.

The degree of order of the atomic arrangement regular structure can be obtained using the following formula (1) (SA Majetich et al., J. Magn. Magn. Mater., 2004, 284, 336-341, P. Andre et al. ., J. Magn. Magn. Mater., 2016, 417, 442-450, Y. Kinemuchi et al., Dalton Trans., 2016, 45, 10936-10941).
However, I _F denotes the intensity of the fundamental peak containing irregular structure and atomic arrangement ordered structure, Is is the peak intensity derived from the atomic arrangement ordered structure, obs is the measured value of the nanoparticle coupling catalyst, bulk rule of The measured value or theoretical value of S = 1 is shown. For example, in the example of PtFe having fct ordered structure, I _F denotes the peak intensity of (111), Is is a peak intensity of (110).

  The nanoparticle-coupled catalyst according to the second embodiment can provide a nanoparticle-coupled catalyst that achieves both excellent load response durability and high ORR activity when this catalyst is applied to PEFC.

[Third Embodiment]
The catalyst layer for the gas diffusion electrode of the third embodiment is different from the above-described embodiment using the capsule catalyst 30 in that the nanoparticle-coupled catalyst 3 is composed of a rod-shaped catalyst, but the basic configuration is as follows. This is the same as in the third embodiment.

  FIG. 6 is a partially enlarged view schematically showing an example of the gas diffusion electrode catalyst layer 2 of the third embodiment. FIG. 7 is sandwiched between the gas diffusion electrode catalyst layer of the third embodiment. The schematic diagram of the electrolyte membrane was shown. As shown in FIGS. 6 and 7, the gas diffusion electrode catalyst layer 2 has a rod-shaped catalyst 40 and an ion conductor 4.

  As shown in FIG. 6, the rod-shaped catalyst 40 forms a generally cylindrical nanoparticle linking skeleton 41, and the ion conductor 4 is disposed therein. The nanoparticle connection skeleton 41 has a network structure in which metals are fused, and has electronic conductivity.

  A large number of voids 43 are formed in the nanoparticle connection skeleton 41, and the voids 43 are formed so as to communicate the inside and the outside of the rod-shaped catalyst that defines the contour. A preferable range of the porosity of the nanoparticle connection skeleton 41 is the same as that in the first embodiment. In the example of FIG. 6, a single rod-shaped gas diffusion electrode catalyst layer 2 is illustrated, but actually, a sheet-like structure is formed by a plurality of rod-shaped catalysts 40.

  Although the thickness which comprises the outline of the rod-shaped catalyst 40 is not specifically limited, Preferably it is 2 nm or more and 50 nm or less. By setting the thickness of the rod-shaped catalyst 40 to 2 nm or more, structural defects can be suppressed and stable production can be performed. The length and shape of the rod-shaped catalyst 40 are not particularly limited, and can be appropriately designed by controlling the shape of the mold.

  In order to achieve good ion conductivity in the catalyst layer, the ion conductor 4 is not only inside the rod-shaped catalyst 40 but also in the void 43 or the rod-shaped catalyst formed in the nanoparticle connection skeleton 41 of the rod-shaped catalyst 40. It is preferable that the outer side of 40 is continuously formed.

  Examples of the preferred material of the rod-shaped catalyst 40 and the ion conductor 4 are the same as those in the first embodiment. The length of the rod-shaped catalyst 40 and the particle diameter of the end face of the cut end are not particularly limited and can be appropriately designed according to the application. The shape and size of the rod-shaped catalyst 40 can be easily controlled by controlling the shape and size of the mold. For example, a mode in which a plurality of rod-shaped catalysts 40 having an end face diameter of about 5 nm to 1 μm are connected in the same direction, or a structure in which they are randomly arranged can be exemplified. The rod-shaped catalyst may be used in a single layer or in multiple layers. In the case of a plurality of layers, the layers may be arranged so as to extend in different directions in order to increase the strength. Further, the major axis direction of the rod-shaped catalyst 40 with respect to the main surface of the polymer electrolyte membrane 5 can be horizontal alignment, vertical alignment, random alignment, or the like. Further, the rod-shaped catalyst 40 and the capsule-shaped catalyst 30 of the first embodiment can be blended and used.

  According to the gas diffusion electrode catalyst layer 2 of the third embodiment, the same effects as those of the above-described embodiment can be obtained. Moreover, by using the rod-shaped catalyst 40 networked with nanoparticles, the mechanical strength can be increased while increasing the surface area that can be used as a catalyst. Moreover, since it is connected in a rod shape, more stable electron conductivity can be secured.

[Fourth Embodiment]
The catalyst layer for the gas diffusion electrode of the fourth embodiment is different from the above-described embodiment in that the nanoparticle-coupled catalyst 3 is a sheet catalyst, but the basic structure and manufacturing method other than those described below are as follows. This is the same as in the previous embodiment.

  In FIG. 8, the schematic diagram of the catalyst layer 2 for sheet-like gas diffusion electrodes of 4th Embodiment is shown. In the gas diffusion electrode catalyst layer 2 according to the fourth embodiment, the nanoparticle-coupled catalyst and the ion conductor are continuously arranged in a sheet shape in the plane and in the thickness direction. That is, the nanoparticle-linked catalyst composed of a sheet-like catalyst has a network-like sheet structure, and the metals are fused together to have electronic conductivity. And the ion conductor is distributedly arranged so that it may contact with this sheet-like catalyst. The thickness of the sheet-like catalyst is not particularly limited and can be appropriately designed according to the use and required performance, but is preferably 10 μm or less, more preferably 2 μm or less, and further preferably 0.5 μm or less. By reducing the thickness of the sheet catalyst, structural defects can be suppressed and stable production can be performed.

  As a method for obtaining a sheet-like nanoparticle-linked catalyst, a film or sheet having a first polarity on the surface is used as a template, and catalyst nanoparticles having the second polarity are impregnated therein to adsorb metal-based nanoparticles. Alternatively, it can be obtained by growing it in situ and subjecting it to a sintering treatment. The film or sheet having the first polarity on the surface is not limited as long as it does not depart from the spirit of the present invention, but a non-woven fabric can be exemplified as a suitable example.

  Although it does not specifically limit as a constituent material of a nonwoven fabric in the range which does not deviate from the meaning of this invention, A silica fiber, a zirconia fiber, etc. can be illustrated as a preferable example. In this case, after performing surface treatment so that these nonwoven fabrics have the first polarity, the metal nanoparticles containing the catalyst nanoparticles having the second polarity are adsorbed or in situ. What is necessary is just to make it grow and to sinter. The ion conductor 4 is a method (i) in which an ion conductive functional group or the like is previously incorporated into silica fiber, zirconia fiber or the like, and / or a method (ii) in which an ion conductive functional group is incorporated into these fibers after the sintering treatment. Can be illustrated.

  Moreover, it is also possible to use the raw material which can be removed after a sintering process or a sintering process as a nonwoven fabric. In this case, the gas diffusion electrode catalyst layer is obtained by entanglement of the ion conductor 4 with the obtained sheet-like nanoparticle-linked catalyst.

  According to the method of the fourth embodiment, the same effect as that of the first embodiment can be obtained. Moreover, there exists an advantage that the formation process of the catalyst layer for gas diffusion electrodes can be simplified. Moreover, since a nanoparticle connection catalyst is constructed in a sheet form, the electron conduction efficiency and the surface area can be increased. In addition, the thickness can be reduced.

  The first to fourth embodiments have been described above, but it goes without saying that other embodiments are also included in the scope of the present invention as long as they match the spirit of the present invention. Moreover, the said embodiment can be combined suitably. In the above, although the example applied to the polymer electrolyte fuel cell using the nanoparticle-linked catalyst according to the present invention has been described, it can be suitably applied to various fuel cells. In addition to fuel cells, the present invention can be applied to all uses where a nanoparticle-linked catalyst is used. In addition, the nanoparticle-linked catalyst of the present invention can be used in a carbon carrier-free manner as described above, but does not exclude the use of a carbon carrier.

<Example>
Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

Example 1
(Process (a))
Template particles having a positive zeta potential were prepared by the following method. First, 160 mg of silica particles (KE-P30: manufactured by Nippon Shokubai Co., Ltd.) and 5 mL of RO water were added to a centrifuge tube. After stirring, the mixture was stirred for 60 minutes with an ultrasonic cleaner. Further, 12 g of poly (diallyldimethylammonium chloride) (hereinafter PDDA, manufactured by Sigma-Aldrich) and 19 mL of RO water were added to another centrifuge tube, and the mixture was stirred for several minutes using a vortex (step 1).

Next, the silica-dispersed aqueous solution was added to a centrifuge tube containing a PDDA aqueous solution, stirred, and then stirred for 60 minutes with an ultrasonic cleaner (step 2). Thereafter, the mixture was centrifuged at 15000 rpm for 5 minutes, and the supernatant was removed (step 3). And RO water was added so that the whole quantity might be 25 mL, it was made to disperse | distribute using a vortex and an ultrasonic washing machine, it centrifuged for 5 minutes at 15000 rpm, and the supernatant liquid was removed. This washing operation was repeated three times to remove excess PDDA (Step 4). Thereby, an aqueous dispersion of PDDA-coated silica particles (template particles) dispersed in RO water was obtained. Hereinafter, the PDDA-coated silica particles prepared in this way are referred to as “PDDA / SiO ₂ ”.

Thereafter, 5 mL of RO water was added to disperse silica adsorbed by PDDA (hereinafter referred to as PDDA / SiO ₂ ) (step 5). Then, 250 μL is added to a pre-weighed container, the solvent is evaporated in an electric furnace at 90 ° C., and then weighed again to determine the weight concentration per unit volume in the white suspension of PDDA / SiO _2. Calculated.

(Process (b))
Next, PtFe nanoparticle-adsorbed PDDA-coated silica particles were synthesized. Tetraethylene glycol (TEG) 100 mL, acetylacetonate iron (III) (Iron (III) acetylacetonate) 240.0 mg and acetylacetonatoplatinum (II) (Platinum (II) acetylacetonate) 241.92 mg were added to a three-necked flask. The mixture was stirred using a sonic cleaner and a stirrer to dissolve the metal precursor (step 6). Thereafter, 30 mL of TEG was added to the eggplant flask, and the PDDA / SiO ₂ solution obtained in the above-described Step 5 was added to 120 mg, and the RO water was removed using an evaporator (Step 7).

Thereafter, the solution of Step 7 was added to the solution of Step 6. 20 ml of TEG was used for the washing. Thereafter, the mixture was stirred for 20 hours or more at room temperature, a set for reflux was assembled, and the mixture was placed in an Ar / H ₂ gas atmosphere, and then stirred at room temperature for 30 minutes. Thereafter, refluxing was performed at 230 ° C. for 2 hours (step 8).

After cooling to room temperature, the step of centrifuging to remove the supernatant and washing with ethanol was performed three times. Then, platinum iron alloy nanoparticles / PDDA / SiO ₂ particles were obtained by drying (step 9).

(Step c [(I) Process])
300 mg of the obtained platinum iron alloy nanoparticles / PDDA / SiO ₂ was dispersed in 5 mL of ethanol, transferred to an autoclave (volume 11 mL), and sealed using a torque wrench. The autoclave was quickly placed in an electric furnace that had been heated to 330 ° C. in advance and heated for 180 minutes. After completion of heating, the autoclave was placed in a water bath and sufficiently cooled. The autoclave was opened and centrifuged (room temperature, rotation speed 4700 rpm, 5 minutes), and then the supernatant was removed. This washing operation was performed three times, transferred to a sample tube using ethanol, and dried at 60 ° C. to obtain a powdered platinum-iron alloy network / SiO ₂ (step 10).

Subsequently, about 30 mg of platinum iron alloy network / SiO _{2 and} 1.16 mL of RO water were added to a 30 mL screw tube bottle, and the mixture was stirred for about 5 minutes using an ultrasonic cleaner. Next, 8 mL of EtOH and 0.4 mL of aqueous ammonia were added to the stirred platinum iron alloy network / SiO ₂ and further stirred. Thereafter, 0.2 mL of tetraethyl orthosilicate (TEOS) was added and stirred at room temperature for 360 minutes.

Subsequently, the mixture was transferred to a centrifuge tube and centrifuged at 15,000 rpm for 5 minutes, and the supernatant was removed. Ethanol was added so that the total amount became 40 mL, and the mixture was dispersed using a vortex and an ultrasonic cleaner, and then centrifuged and the supernatant was removed in the same manner as described above. This washing operation was repeated three times and then dried to obtain SiO ₂ coating / platinum iron alloy network / SiO ₂ . FIG. 9 shows a transmission electron microscope (TEM, Hitachi H8100 transmission electron microscope) image of silica-coated / PtFe network / SiO ₂ particles. As shown in FIG. 9, a smooth silica surface was observed over the entire surface, and it was confirmed that silica was coated on the catalyst surface. Further, from the TEM image, it was confirmed that the silica layer covered about 50 nm on the catalyst surface.

Subsequently, 50-300 mg of SiO ₂ coating / platinum iron alloy network / SiO ₂ was placed on a bakeware, and the temperature was raised over 60 minutes in a H ₂ / N ₂ (= 3/10) atmosphere using a tube furnace. And heat treatment was performed. The heat treatment temperature was 700 ° C. for 3 hours. Then, after sufficiently cooled at room temperature to obtain a SiO ₂ coating / platinum-iron alloys network / SiO _2.

(Process (d))
In a 100 mL Teflon (registered trademark) beaker, 30 mL of 10 M NaOH aqueous solution, SiO ₂ coating / platinum iron alloy network / SiO ₂ were added, and the mixture was heated and stirred at 90 ° C. for 180 minutes to dissolve SiO ₂ . Next, the mixture was transferred to a centrifuge tube, centrifuged at 4700 rpm for 5 minutes, and the supernatant was removed. Thereafter, RO water was added so that the total amount became 40 mL, and after centrifugation at 4700 rpm for 5 minutes, the supernatant was removed. This washing operation was performed three times, transferred to a sample tube using ethanol, and dried at 60 ° C. to obtain a platinum-iron alloy nanoparticle-coupled catalyst with controlled regularity. FIG. 10 shows a transmission electron microscope (TEM) image of the obtained hollow capsule-shaped PtFe alloy nanoparticle-coupled catalyst.

[Example 2]
A platinum-iron alloy nanoparticle coupled catalyst was obtained in the same manner as in Example 1 except that the heat treatment temperature in step (c) (I) was changed to 800 ° C.

[Example 3]
A platinum iron alloy nanoparticle coupled catalyst was obtained by the same method as in Example 1 except that the heat treatment temperature in step (c) (I) was changed to 900 ° C.

[Example 4]
A platinum iron alloy nanoparticle coupled catalyst was obtained by the same method as in Example 2 except that the concentration of the aqueous sodium hydroxide solution in step (d) was changed to 3M.

[Example 5]
A platinum iron alloy nanoparticle coupled catalyst was obtained in the same manner as in Example 2 except that the process (II) was applied in step (c). Specifically, step (b) was performed in the same manner as in Example 2, and then step c was performed.

(Step (c) [Process of (II)])
About 30 mg of the particles obtained in the step (b) and 1.16 mL of RO water were added to a 30 mL screw tube and stirred for about 5 minutes using an ultrasonic cleaner. Next, 8 mL of EtOH and 0.4 mL of aqueous ammonia were added to the stirred platinum iron alloy nanoparticles / PDDA / SiO ₂ and further stirred. Thereafter, 0.2 mL of tetraethyl orthosilicate (TEOS) was added and stirred at room temperature for 360 minutes.

Subsequently, the mixture was transferred to a centrifuge tube and centrifuged at 15,000 rpm for 5 minutes, and the supernatant was removed. Ethanol was added so that the total amount became 40 mL, and the mixture was dispersed using a vortex and an ultrasonic cleaner, and then centrifuged and the supernatant was removed in the same manner as described above. This washing operation was repeated three times and then dried to obtain SiO ₂ coating / platinum iron alloy nanoparticles / PDDA / SiO ₂ .

Thereafter, heat treatment was performed at 800 ° C. in H ₂ / N ₂ for 3 hours to simultaneously form a nanoparticle-linked skeleton and an atomic arrangement regular structure. Then, after sufficiently cooled at room temperature to obtain a SiO ₂ coating / platinum-iron alloys network / SiO _2.

(Process (d))
30 mL of 3M NaOH aqueous solution and SiO ₂ coating / platinum iron alloy network / SiO ₂ were added to a 100 mL Teflon beaker, and heated and stirred at 90 ° C. for 180 minutes to dissolve SiO ₂ . Next, the mixture was transferred to a centrifuge tube, centrifuged at 4700 rpm for 5 minutes, and the supernatant was removed. Thereafter, RO water was added so that the total amount became 40 mL, and after centrifugation at 4700 rpm for 5 minutes, the supernatant was removed. This washing operation was performed three times, transferred to a sample tube using ethanol, and dried at 60 ° C. to obtain a platinum-iron alloy nanoparticle-coupled catalyst with controlled regularity. FIG. 11 shows a transmission electron microscope (TEM) image of the obtained hollow capsule-shaped PtFe alloy nanoparticle-coupled catalyst.

[Comparative Example 1]
A platinum iron alloy nanoparticle coupled catalyst was obtained in the same manner as in Example 2 except that the silica coating and heat treatment in step (c) were not performed (supercritical treatment was performed).

[Comparative Example 2]
The platinum-iron alloy nanoparticle coupled catalyst obtained in Comparative Example 1 was subjected to the heat treatment in Step (c) at 800 ° C. for 2 hours in an H ₂ / N ₂ (= 3/10) atmosphere. Got.

[Comparative Example 3]
Pt / C (Tanaka Kikinzoku Kogyo TEC10E50E) was used as it was. It was confirmed that the ordered alloy structure was not observed in the fine particles of Comparative Example 3.

<TEM image>
In FIG. 10, the TEM image of the catalyst of the comparative example 1 and Examples 1-3 is shown. As shown in the figure, as in Comparative Example 1 in which the heat treatment step (c) was not performed, the catalysts of Examples 1 to 3 also maintained the capsule structure and also maintained the nano-sized network structure. Confirmed that it has been. From the TEM image, it was observed that the network thickness slightly increased as the heat treatment temperature increased.

  Also in the catalyst of Example 5, a hollow capsule-like nanoparticle-linked network structure was observed as shown in FIG. By coating the silica layer in advance, a nano-sized network structure in which nanoparticles are connected only by performing a heat treatment at normal pressure without performing a heat treatment using a special apparatus such as a supercritical treatment in the step (c). Found to form.

  FIG. 12 shows a TEM image of the catalyst of Comparative Example 2. As shown in the figure, in Comparative Example 2 in which the heat treatment was performed without performing the silica coating in the step (c), the catalysts were fused and aggregated, and the network structure and the capsule structure could not be maintained.

<Results of XRD measurement>
For the powder samples of Examples 1 to 3 and Comparative Example 1, XRD (Ultima IV, manufactured by Rigaku) measurement (diffractive angle range: 2θ = 10 to 90 °, scan speed: 2θ = 1 ° / min) was performed. . The degree of order S in the platinum iron alloy nanoparticle-coupled catalyst was determined using the following mathematical formula (2). The degree of ordering was calculated by using the ratio of the peak intensity I ₍₁₀₀₎ at (110) near 33 ° and the peak intensity I ₍₁₁₁₎ at (111) near 41 ° derived from the atomic arrangement ordered structure. For the bulk data, PDF library card 03-065-9121 was used.

FIG. 13 shows the XRD measurement results, and Table 1 shows the regularity S.

  By performing the process of step (c) (I), it was confirmed that the peak derived from (001) near 24 ° and the peak derived from (110) near 33 ° became clear as shown in FIG. did. These peaks indicate an fct (face centered tetragonal) atomic arrangement regular structure. Moreover, since the peak of the (111) plane in the vicinity of 2θ = 40 ° is shifted to the high angle side from the peak position of the (111) plane of pure platinum of Comparative Example 3, it was confirmed that alloying occurred. did.

  By performing the process of step (c) (II), it was confirmed that the peak derived from (001) near 24 ° and the peak derived from (110) near 33 ° became clear as shown in FIG. did. These peaks indicate an fct (face centered tetragonal) atomic arrangement regular structure. Moreover, since the peak of the (111) plane in the vicinity of 2θ = 40 ° is shifted to the high angle side from the peak position of the (111) plane of pure platinum of Comparative Example 3, it was confirmed that alloying occurred. did.

  Moreover, it can be seen from the results of Table 1 that the regularity S of the metal network (nanoparticle linking skeleton) is improved in both processes (I) and (II) of the step (c). In particular, under the heat treatment conditions of Examples 2 to 5 at 800 ° C. or higher, it was confirmed that the degree of regularity S was increased nearly twice as compared with Comparative Example 1 in which the heat treatment of step (c) was not performed. Moreover, despite the heat treatment at a high temperature, the nano-sized network structure was maintained, suggesting that the silica coating layer suppressed the fusion of the metal catalyst.

<Electrochemical evaluation>
Electrochemical evaluation of the nanoparticle-linked catalyst was performed by the rotating disk electrode (RDE) method. For electrochemical evaluation, a glassy carbon (geometric region: 0.196 cm ² ) electrode polished with aluminum particles was used.

(Production of RDE electrode)
2.5-5.0 mg of catalyst, 6.25 mL of 25 vol% isopropyl alcohol (IPA) aqueous solution, 12.5 μL of Nafion (registered trademark, 5 wt%, manufactured by Sigma-Aldrich) was added to a 30 mL screw tube. . Next, the mixture was dispersed for 1 hour or more while cooling using an ultrasonic cleaner. Thereafter, 10 μL of the prepared catalyst ink was dropped onto the polished glassy carbon electrode. This was dried to produce an electrode carrying a catalyst.

  CV (Cyclic voltammetry) measurement was performed using the catalyst samples of Examples 1, 2, 4, 5 and Comparative Example 1 as a working electrode, a platinum wire as a counter electrode, and a reversible hydrogen electrode (RHE) as a reference electrode. . As pretreatment by acid cleaning, 0.1 M perchloric acid in a nitrogen atmosphere was used as the electrolyte, and the CV cycle was performed 50 times at 0.05 to 1.2 V, a sweep rate of 50 mV / s, and room temperature. After acid cleaning, CV measurement was performed at a sweep rate of 20 mV / s, and an electrochemically active platinum surface area (ECSA) was calculated. FIG. 15 shows the results of CV measurement in Examples 1 and 2, FIG. 16 shows the results of Example 4 and Comparative Example 1, and FIG. 17 shows the results of CV measurement using the catalysts of Examples 5 and 1 as working electrodes.

  Further, with respect to the catalyst samples of Examples 1, 2, 4, 5 and Comparative Example 1, LSV (Linear sweep voltammetry) measurement was performed under the following conditions, and the oxygen reduction reaction activity was calculated. Specifically, at an electrode rotation speed of 1600 rotations / minute, a potential scan is performed from 0.05 V to 1.2 V at a sweep speed of 20 mV / s in an oxygen atmosphere. The oxygen reduction reaction activity per mass (mass activity per mass of mass (Mass Activity (MA)) was evaluated.

  18 shows the LSV measurement results of Examples 1 and 2 obtained, FIG. 19 shows the LSV measurement results of Example 4 and Comparative Example 1, and FIG. 20 shows the LSV measurement results of Example 5 and Comparative Example 1. Furthermore, the activity per surface area of platinum, which is electrochemically active, and the ORR surface specific activity (Specific Activity (SA)) were calculated from ECSA and MA. The results are shown in Table 2. Table 2 also shows the results when a similar experiment was performed on the catalyst of Comparative Example 3.

  The mass activity and ORR surface specific activity were greatly improved in Example 4 under the same conditions except that the alkali treatment in the step (d) was carried out with 10M NaOH and Example 3 was carried out with 3M NaOH. Confirmed that it will be. These values in Example 4 are comparable to those in Comparative Example 1. Good ORR surface specific activity was also obtained in Example 5 in which a PtFe nanoparticle-linked network was formed only by heat treatment without supercritical treatment.

<Load response durability test>
A load response durability test for accelerating the elution of the catalytic metal was performed on the samples of Examples 1, 2, 4 and Comparative Example 1 prepared by the above method according to the FCCJ protocol under the following conditions. FIG. 21 is an explanatory diagram of the FCCJ protocol applied to the durability test. A cycle in which a load of 0.6 V and 1.0 V was applied for 3 seconds each was taken as one cycle. After sweeping a predetermined potential cycle, CV measurement and LSV measurement were performed in the same manner as described above, and ECSA, mass activity, and surface specific activity were evaluated. The load response potential cycle was performed at 60 ° C. using an N ₂ saturated 0.1 M HClO ₄ aqueous solution as the acid electrolyte.

  FIG. 22 shows the CV curve at the initial stage and after 10,000 cycles in Example 2, and FIG. 23 shows the LSV curve. Further, FIG. 24 shows the CV curve at the beginning and after 10,000 cycles in Example 4, and FIG. 25 shows the LSV curve. FIG. 26 is a graph plotting changes in mass activity when the durability test was performed on the catalyst samples of Examples 2 and 4 and Comparative Examples 1 and 3. FIG. 27 is a graph plotting changes in the surface specific activity when the durability test is performed on the sample.

  22 to 25, it was found that the initial CV curve and LSV curve were substantially maintained even after 10,000 cycles in both Example 2 and Example 4. FIG. 26 shows that the initial mass activity is high in Example 4 and Comparative Example 1, but after 10,000 cycles, the sample of Example 4 having a high degree of order fired at 800 ° C. has the highest mass activity. . Although the initial mass activity in Example 2 is low, the value after Comparative Example 1 and Comparative Example 3 is higher after 10,000 cycles. Also, as for the ORR surface specific activity, from FIG. 27, the sample of Example 4 and Comparative Example 1 showed a high value, but after 10,000 cycles, the sample of Example 4 had the highest ORR surface specific activity. Next, it can be seen that Example 4 is high. That is, it was confirmed that the samples of Examples 2 and 4 had high activity retention and excellent durability. In particular, Example 4 has a high initial activity and the highest catalytic activity after 10,000 cycles.

  FIG. 28 shows a plot of normalized ORR surface specific activities of Examples 2 and 4 and Comparative Example 1. From these figures, the samples of Examples 2 and 4 having a high degree of order of about 0.8 are compared with Comparative Example 1 (order degree 0.44) having a low degree of order, and the retention rate of the ORR surface specific activity ( It can be seen that the evaluation (ORR surface specific activity after the cycle with respect to the initial value) is high. This suggests that by taking a thermodynamically stable atomic arrangement ordered structure (fct structure), iron elution can be suppressed and durability can be improved.

<EDX line mapping analysis>
Next, the result of EDX line mapping analysis will be described. The catalyst for Example 2 and 4, respectively (1) an initial product (2) after acid washing (0.1 M, HClO ₄ aq. In _{N 2} atmosphere, CV50 cycles at a sweep rate of 50 mV / s), (3) Three samples after the durability test (after a load cycle of 10,000 cycles) were evaluated. Moreover, about the catalyst of the comparative example 1, it measured also about the initial stage goods and two samples after acid washing. FIG. 29 shows Example 2, FIG. 30 shows Example 4, and FIG. 31 shows an EDX line mapping diagram of Comparative Example 1.

  From the results of the line mapping analysis shown in FIGS. 29 and 30, it was confirmed that elution of iron can be significantly suppressed in the load response durability test by increasing the degree of order S of the nanoparticle-coupled catalyst. Specifically, the nanoparticle-linked catalyst of Example 2 was able to suppress the elution of iron in the acid cleaning, and it was confirmed that the elution was slight even after the 10,000 cycle test. When the thickness of the Pt layer (Pt-rich layer) on the catalyst surface was determined, the initial thickness and the thickness after acid cleaning were almost the same, and both Examples 2 and 4 were 0.4 nm. This thickness is equivalent to about 2 platinum atomic layers. The thickness of the platinum-rich layer after 10,000 cycles was 0.5 nm in Example 2 and 0.7 nm in Example 4, and it was confirmed that a thin platinum-rich layer can be maintained by suppressing elution of iron.

  On the other hand, the thickness of the Pt-rich layer of the nanoparticle-coupled catalyst layer of Comparative Example 1 that was not subjected to the heat treatment in the step (d) was 0.8 nm after the acid cleaning. This was equivalent to a 3-4 platinum atomic layer, and it was confirmed that there was a slight thickness compared to the above examples. From these results, it is suggested that elution of Fe from the catalyst surface can be suppressed in the acid cleaning and the durability test by improving the degree of order by heat treatment. It is suggested that a high degree of order in the nanoparticle-linked catalyst is important for improving the load response durability.

  FIG. 32 shows a bar graph of the ORR mass activity after 10,000 cycles of the initial products of Examples 2 and 4 and Comparative Examples 1 and 3, and FIG. 33 shows a bar graph of the ORR surface specific activity of the same sample. In Comparative Example 1 without heat treatment in step (d), the ORR surface specific activity after 10,000 cycles decreased to 28% of the initial value, but in Example 2, the ORR surface specific activity retention was 90%. It was confirmed that the durability was significantly improved. Also in Example 4 where the alkali treatment was performed under milder conditions than Example 2, the ORR surface specific activity retention was sufficiently high, and both the ORR mass activity and surface specific activity after 10,000 cycles were in Example 2. It was found to be larger than Comparative Examples 1 and 3. In addition, Patent Document 1 demonstrates the excellent start / stop durability of a carbon-free nanoparticle-linked catalyst. From the above results, the present invention can provide a nanoparticle-linked catalyst that achieves both excellent load response / startup / stop durability and high ORR activity.

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Gas diffusion electrode catalyst layer 3 Nanoparticle connection catalyst 4 Ion conductor 5 Polymer electrolyte membrane 6 Cell 7 External circuit 10 Anode unit 11 Anode catalyst layer 12, 22 Gas diffusion layer 13, 23 Separator 14, 24 Gas Channel 20 Cathode unit 21 Cathode catalyst layer
30 Capsule-shaped catalyst 31 Nanoparticle linking skeleton 33 Void 35 Template particle 36 Metal nanoparticle 37 Silica layer 40 Rod-shaped catalyst 41 Nanoparticle linking skeleton
43 Air gap

Claims (12)

Forming a mold having a desired shape and having a first polarity;
A step of adsorbing metal-based nanoparticles containing catalyst nanoparticles having a second polarity opposite to the first polarity on the surface of the template, or growing them in situ to obtain a template with metal-based nanoparticles ( b) and
For the mold with metal nanoparticles,
(I) A nanoparticle-linked skeleton formed of an alloy of at least two kinds of metal atoms, ie, a first metal atom having fuel cell catalytic activity and a second metal atom that improves the catalytic activity of the first metal atom is formed by heat treatment. Then, after covering at least part of the surface with a silica layer, the step of increasing the degree of order of the atomic arrangement regular structure of the nanoparticle-linked skeleton by heat treatment, and (II) covering at least part of the surface with the silica layer Thereafter, a nanoparticle linking skeleton composed of an alloy of at least two kinds of metal atoms, ie, a first metal atom having fuel cell catalytic activity and a second metal atom that improves the catalytic activity of the first metal atom, is formed by heat treatment. And increasing the degree of order of the atomic arrangement regular structure of the nanoparticle-linked skeleton,
A step (c) of performing any one of
The manufacturing method of the nanoparticle connection catalyst which comprises the process (d) which removes the said casting_mold | template and the said silica layer after a process (c).   The method for producing a nanoparticle-coupled catalyst according to claim 1, wherein the nanoparticle-coupled catalyst is at least one of a capsule shape, a rod shape, and a sheet shape.   The said process (c) is 500 degreeC-1300 degreeC, The manufacturing method of the nanoparticle connection catalyst of Claim 1 or 2.   The nanoparticle-linked skeleton is made of an alloy containing two or more kinds selected from platinum, iron, cobalt, nickel, palladium, silver, gold, copper, ruthenium, iridium, molybdenum, rhodium, chromium, tungsten, and manganese. The manufacturing method of the nanoparticle connection catalyst in any one of 1-3.   The nanoparticle coupling | bonding in any one of Claims 1-4 which adjust the process conditions of the process of a process (d) so that the atom located in the surface layer of the said nanoparticle coupling | bonding skeleton is mainly formed from a 1st metal atom. A method for producing a catalyst.   The nanoparticle connection catalyst obtained by the manufacturing method of the nanoparticle connection catalyst in any one of Claims 1-5.   A first metal atom made of a sintered body and having nanoparticles connected to each other and having a fuel cell catalytic activity, and a metal of a different type from the first metal atom, and improving the catalytic activity of the first metal atom. A nanoparticle-coupled catalyst having an electron conductivity having a nanoparticle-linked skeleton having an atomic arrangement regular structure composed of at least two kinds of metal atom alloys and having an order of the atomic arrangement regular structure of 0.5 or more.   The nanoparticle-linked catalyst according to claim 7, which is at least one of a capsule-shaped catalyst, a rod-shaped catalyst, and a sheet-shaped catalyst.   The nanoparticle-linked skeleton is two or more types selected from platinum, iron, cobalt, nickel, palladium, silver, gold, copper, ruthenium, iridium, molybdenum, rhodium, chromium, tungsten, and manganese. The nanoparticle-linked catalyst according to claim 7 or 8, comprising an alloy containing Nanoparticle-linked catalyst according to any one of claims 7 to 9,
A catalyst layer for a gas diffusion electrode comprising the nanoparticle-coupled catalyst and an ionic conductor that is at least partially in contact. A membrane electrode assembly in which a solid polymer electrolyte membrane is disposed between an anode catalyst layer and a cathode catalyst layer,
The membrane electrode assembly which uses the catalyst layer for gas diffusion electrodes of Claim 10 for at least one of the said anode catalyst layer and the said cathode catalyst layer.   A fuel cell comprising the membrane electrode assembly according to claim 11.