JP6881747B2 - Water electrolyzer, membrane electrode assembly, Ru-based nanoparticle linking catalyst and Ru-based nanoparticle linking catalyst layer manufacturing method, fuel cell and methane hydrogenation catalyst - Google Patents

Description

The present invention relates to a water electrolyzer that electrolyzes water to generate hydrogen gas and oxygen gas. The present invention also relates to a method for producing a Ru-based nanoparticle linking catalyst and a Ru-based nanoparticle linking catalyst layer, and a membrane electrode assembly using the catalyst. Further, the present invention relates to a fuel cell for extracting electric energy and a catalyst for hydrogenation of methane.

Since water electrolysis can convert electric power into hydrogen without generating carbon dioxide, it is attracting attention as an electric power-hydrogen storage system that stores renewable energy as hydrogen energy. Examples of the water electrolysis method include alkaline water electrolysis, solid polymer type water electrolysis, and high temperature water electrolysis. Of these, the polymer electrolyte electrolysis has a structure in which a solid polymer electrolyte membrane is sandwiched between a pair of electrodes, and oxygen gas is generated from one electrode and hydrogen gas is generated from the other electrode. Since the distance between the pair of electrodes is small and the method is advantageous for high current density operation, research and development are being vigorously carried out.

In particular, various proposals have been made for the catalyst layer of the electrode, which is the key to improving the performance. For example, Non-Patent Document 1 proposes a catalyst layer using carrier-free Ir and Ru oxide particles. Further, Non-Patent Document 2 proposes a catalyst layer in which Pt-M (M = Ir, Re, Ru, Pd) and Pt-Ru-M (M = Ir, Pd) particles are supported on carbon. There is. Further, Non-Patent Document 3 discloses a catalyst layer using Ni, Fe oxides supported on a stainless steel mesh, and Non-Patent Document 4 discloses a catalyst using Ni, Fe oxide particles supported on a Ni mesh. Layers have been proposed.

The present inventors have recently proposed a technique having a nanoparticle connection structure suitable for a fuel cell, although it is not a technique relating to an electrolysis device (Patent Document 1).

Japanese Unexamined Patent Publication No. 2015-92464

International Journal of Hydrogen Energy, 2007, 32, 2320-2324 Journal of The Electrochemical Society, 2009, 156, 3, B363-B369 Phys. Chem. Chem. Phys., 2011, 13, 1162-1167 Energy Environ. Sci., 2012, 5, 7869-

In order to promote the spread of water electrolyzers, a technique for improving the catalytic activity of an anode catalyst that decomposes water is desired. Further, in addition to the improvement of catalytic activity, improvement of durability is required. The method of supporting the metal nanoparticles on the carbon particles has an advantage that the effective surface area of the metal catalyst can be increased, but carbon corrosion occurs on the high potential side, so that there is a problem in durability. Further, a method of supporting metal particles on a Ti fiber carrier or the like instead of a carbon carrier is known, but there is a problem that the gas diffusion resistance generated by water electrolysis increases because the catalyst layer becomes thick. ..
Although the problems in the water electrolyzer have been described above, the same problems may occur in the hydrogenation reaction of the fuel cell and methane gas.

The present invention has been made in view of the above background, and is an aqueous electrolyzer, a membrane electrode assembly, a Ru-based nanoparticle coupling catalyst, and Ru, which are excellent in durability and capable of increasing catalyst efficiency even without a carbon carrier. An object of the present invention is to provide a method for producing a system nanoparticle connection catalyst layer, a fuel cell, and a catalyst for hydrogenation of methane.

As a result of diligent studies by the present inventors, they have found that the problems of the present invention can be solved in the following aspects, and have completed the present invention.
[1]: A water electrolyzer that electrolyzes water to generate hydrogen and oxygen, which is in contact with an electrolyte, an anode electrode in contact with the electrolyte, and is connected to the anode electrode through an external circuit. Ru-based nanoparticles exhibiting electron conductivity, comprising a cathode electrode that generates hydrogen gas, and a sintered body in which Ru-containing metal nanoparticles are linked to at least a part of the surface of the anode electrode in contact with the electrolyte. A water electrolyzer that uses a ligated catalyst.
Here, examples of the "electrolyte" include an aqueous electrolyte solution and an electrolyte polymer. The "Ru-containing metal nanoparticles" are composed of ruthenium nanoparticles composed of Ru (ruthenium) alone, a mixture of the ruthenium nanoparticles and metal nanoparticles composed of other metal elements, and an alloy of ruthenium and other metals. Refers to metal nanoparticles. Further, these metal nanoparticles may be metal oxides. The Ru-containing metal nanoparticles may be a single type or a plurality of types may be used in combination. Further, the "Ru-based nanoparticle connection catalyst" refers to a catalyst in which metal nanoparticles are sintered and has a portion in which the nanoparticles are connected to each other and a void portion, which are connected in a network shape, and at least Ru as metal nanoparticles. Containing metal nanoparticles are used. The form of the catalyst is not particularly limited, and a desired shape can be obtained depending on the application.

[2]: The water electrolysis apparatus according to [1], wherein the Ru-based nanoparticle coupling catalyst is at least one of a capsule-shaped catalyst, a rod-shaped catalyst, and a sheet-shaped catalyst.
[3]: The water electrolysis apparatus according to [1] or [2], wherein the Ru-based nanoparticle linking catalyst is carbon carrier-free.
[4]: The water electrolysis apparatus according to any one of [1] to [3], wherein the Ru-based nanoparticle coupling catalyst contains an fcc structure.
[5]: The water electrolysis apparatus according to any one of [1] to [4], wherein the anode catalyst layer has a thickness of 10 μm or less.

[6]: A membrane electrode assembly in which a solid polymer electrolyte film is arranged between an anode catalyst layer and a cathode catalyst layer, and a sintered body is provided on at least one of the anode catalyst layer and the cathode catalyst layer. A membrane electrode assembly in which a Ru-based nanoparticle connection catalyst is used, which comprises a Ru-based nanoparticle connection catalyst in which Ru-containing metal nanoparticles are linked to exhibit electron conductivity.
[7]: The membrane electrode assembly according to [6], wherein the anode catalyst layer has a thickness of 10 μm or less.
[8]: The membrane electrode assembly according to [6] or [7], wherein the Ru-based nanoparticle coupling catalyst is carbon carrier-free.
[9]: The membrane electrode assembly according to any one of [6] to [8], wherein the Ru-based nanoparticle coupling catalyst contains an fcc structure.

[10]: A step (a) of forming a mold having a desired shape and having the first polarity, and
The step (b) of adsorbing or in-situ growing Ru-containing metal nanoparticles having a second polarity opposite to the first polarity on the mold surface.
After the step (b), a step (c) of obtaining a Ru-based nanoparticle coupling catalyst by sintering treatment, and
The step (d) of incorporating the Ru-based nanoparticle linking catalyst and an ionic conductor having a contact site is provided.
The method for producing a Ru-based nanoparticle-linked catalyst layer, wherein the ionic conductor in step (d) is at least one of the following (i) to (iii).
(I) A component contained in the mold incorporated in the step (a).
(Ii) It is obtained by converting the component contained in the template as a precursor after the step (c).
(Iii) It is introduced by adding a new step after the step (c).
[11]: The Ru-based nanoparticle coupling catalyst is at least one of a capsule-shaped catalyst, a rod-shaped catalyst, and a sheet-shaped catalyst.
The method for producing a Ru-based nanoparticle-linked catalyst layer according to [10], wherein the ion conductor is provided inside or outside the Ru-based nanoparticle-linked catalyst.
[12]: The method for producing a Ru-based nanoparticle-linked catalyst layer according to [10] or [11], wherein the sintering treatment is a supercritical treatment or a subcritical treatment.
[13]: The Ru-based nanoparticle-linked catalyst layer according to any one of [10] to [12], wherein the template modifies the surface of the pre-template particles and the surface is composed of template particles having the first polarity. Manufacturing method.

[14]: A Ru-based nanoparticle linking catalyst made of a sintered body and having Ru-containing metal nanoparticles linked to each other to have electron conductivity.
[15]: A fuel cell having a membrane electrode assembly in which a solid polymer electrolyte membrane is arranged between an anode catalyst layer and a cathode catalyst layer.
The membrane electrode assembly is the membrane electrode assembly according to any one of [6] to [9].
The solid polymer electrolyte membrane is a fuel cell in which at least a part of the Ru-based nanoparticle linking catalyst is in contact with the fuel cell and has an ionic conductor.
[16]: A catalyst for reforming methane gas into hydrogen gas.
A catalyst for hydrogenation of methane, which comprises a sintered body and uses a Ru-based nanoparticle connection catalyst having Ru-containing metal nanoparticles linked to have electron conductivity.

According to the present invention, a method for producing a water electrolyzer, a membrane electrode assembly, a Ru-based nanoparticle linking catalyst, and a Ru-based nanoparticle linking catalyst layer, which have excellent durability and can increase catalyst efficiency even without a carbon carrier. It has an excellent effect of being able to provide a fuel cell and a catalyst for hydrogenation of methane.

The schematic cross-sectional view which shows an example of the main part of the water electrolysis apparatus which concerns on 1st Embodiment. The schematic explanatory view of the water electrolysis reaction of the solid polymer type water electrolysis apparatus which has a cation exchange membrane. The schematic explanatory view of the water electrolysis reaction of the solid polymer type water electrolysis apparatus which has an anion exchange membrane. The schematic partial enlarged view of the anode catalyst layer which concerns on 1st Embodiment. The schematic diagram of the capsule-shaped catalyst which concerns on 1st Embodiment. The schematic perspective view in the VI-VI cutting line of FIG. The explanatory view which shows the manufacturing process of the anode catalyst layer which concerns on 1st Embodiment. The explanatory view which shows the manufacturing process of the anode catalyst layer which concerns on 1st Embodiment. The explanatory view which shows the manufacturing process of the anode catalyst layer which concerns on 1st Embodiment. The explanatory view which shows the manufacturing process of the anode catalyst layer which concerns on 1st Embodiment. The schematic partial enlarged view of the anode catalyst layer which concerns on 2nd Embodiment. The schematic partial enlarged view of the anode catalyst layer which concerns on 3rd Embodiment. The schematic explanatory view of the anode catalyst layer which concerns on 5th Embodiment. FIG. 6 is a schematic cross-sectional view showing an example of a main part of the water electrolysis apparatus according to the sixth embodiment. FIG. 6 is a schematic cross-sectional view showing an example of a main part of the fuel cell according to the seventh embodiment. The schematic explanatory view of the methane hydrogenation apparatus which concerns on 8th Embodiment. Scanning electron microscope image of the Ru-based nanoparticle connection catalyst of Example 1. A transmission electron microscope image of the Ru-based nanoparticle coupling catalyst of Example 1. A transmission electron microscope image of the Ru-based nanoparticle coupling catalyst of Example 2. A transmission electron microscope image of the Ru-based nanoparticle coupling catalyst of Example 3. The figure which shows the XRD measurement result of the Ru-based nanoparticle coupling catalyst of Examples 1 to 3 and Comparative Example 1. FIG. LSV curve in the evaluation of oxygen evolution reaction activity of the catalysts of Examples 1 and Comparative Examples 1 and 3 in an acidic environment. LSV curve in the evaluation of oxygen evolution reaction activity of the catalysts of Examples 1 and Comparative Examples 1 and 3 in an alkaline environment. LSV curve in the evaluation of hydrogen generation reaction activity of the catalysts of Examples 1 and Comparative Examples 1 and 3 in an acidic environment. LSV curve in the evaluation of hydrogen generation reaction activity of the catalysts of Examples 1 and Comparative Examples 1 and 3 in an alkaline environment. CV curves in evaluating the activity of the methanol oxidation reaction of the catalysts of Examples 1 to 3 and Comparative Examples 2 and 3 in an aqueous methanol solution. Partial enlarged explanatory view of the anode catalyst layer of the water electrolysis apparatus which concerns on a conventional example.

Hereinafter, an example of an embodiment to which the present invention is applied will be described. The numerical value specified in the present specification is a value obtained by the method disclosed in the embodiment or the embodiment. Further, the numerical values "A to B" specified in the present specification refer to a range in which the numerical values A and the numerical values A are larger than the numerical values B and the numerical values B are satisfied. The following description and drawings have been simplified as appropriate to clarify the description. In addition, matters necessary for the practice of the present invention 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 the art.

[First Embodiment]
FIG. 1 shows an example of a schematic diagram of a main part of the water electrolyzer according to the first embodiment. The water electrolyzer 1 includes a solid polymer electrolyte membrane 5 having an ion-conducting property that functions as an electrolyte, an anode electrode 10 to which water is supplied, a cell 6 having a cathode electrode 20 for generating hydrogen gas, and an external circuit. Has 7. Normally, in the water electrolyzer 1, a plurality of cells 6 are stacked.

In the anode electrode 10, the anode catalyst layer 11 and the gas diffusion layer 12 are arranged in this order from the solid polymer type electrolyte membrane (hereinafter, also referred to as “electrolyte film”) 5 side, and the cathode electrode 20 is the cathode catalyst layer 21 and gas. The diffusion layer 22 is arranged in this order from the electrolyte film 5 side. A separator 13 is arranged outside the anode electrode 10, and a separator 23 is arranged outside the cathode electrode 20. The anode electrode 10 and the cathode electrode 20 can be said to be gas diffusion electrodes because gas, water, and the catalyst layer can come into contact with each other at the same time.

The electrolyte membrane 5 includes a cation exchange membrane (Cation Exchange Membrane (PEM)) and an anion exchange membrane (Anion Exchange Membrane (AEM)). When a cation exchange membrane is used, as shown in the schematic diagram of FIG. 2, on the anode side,
H ₂ O → 2H ⁺ + 1 / 2O ₂ + 2e ⁻
Reaction occurs, and oxygen gas and hydrogen ions are generated. Then, the electrons are supplied to the cathode electrode 20 through the external circuit 7. On the other hand, hydrogen ions move to the cathode electrode 20 side via the electrolyte membrane 5. Then, on the cathode electrode 20 side, 2H ⁺ + 2e ⁻ → H ₂
Reaction occurs and hydrogen gas is generated.
On the other hand, when an anion exchange membrane is used, as shown in FIG. 3, hydroxide ions (OH ⁻ ) move to the anode side via the electrolyte membrane 5. Then, on the anode side, 2OH ⁻ → H ₂ O + 1 / 2O ₂ + 2e ⁻
Reaction occurs. That is, oxygen gas is generated. Then, the electrons are supplied to the cathode side via an external circuit. On the other hand, on the cathode side, 2H ₂ O + 2e ⁻ → 2OH ⁻ + H ₂
Reaction occurs and hydrogen gas is generated.
The first embodiment can be applied to both a cation exchange membrane and an anion exchange membrane as the electrolyte membrane 5, but here, a case where a cation exchange membrane is used will be described.

When a voltage is applied between both electrodes while supplying water to the anode electrode 10, the water is electrolyzed at the anode electrode 10 to generate ^{oxygen and hydrogen ions (H +).} The hydrogen ions pass through the electrolyte membrane 5 and move to the cathode electrode, where they receive electrons from the external circuit 7 and become hydrogen gas. As the electrolyte membrane 5, a membrane that allows substantially only hydrogen ions to permeate is preferable, but a membrane that allows water to move may be used. In the latter case, it is necessary to construct a drainage system on the cathode electrode 20 side as well.

An anode catalyst layer 11 made of a Ru-based nanoparticle connecting catalyst is provided on at least a part of the surface of the anode electrode 10 in contact with the electrolyte membrane 5. The Ru-based nanoparticle linking catalyst comprises a sintered body in which Ru-containing metal nanoparticles are linked, and has electron conductivity. The anode catalyst layer 11 may be a Ru-based nanoparticle-linked catalyst alone, or may further have an ionic conductor. In this case, the ionic conductor also functions as an electrolyte together with the electrolyte membrane 5. In addition, other components can be included as long as the gist of the present invention is not deviated.

As the cathode catalyst layer 21 constituting the cathode electrode 20, a known catalyst layer can be appropriately used, but the above-mentioned Ru-based nanoparticle coupling catalyst can also be preferably used. By using the Ru-based nanoparticle-linked catalyst as the cathode catalyst layer 21, the thickness can be significantly reduced as compared with the conventional catalyst layer in which the metal nanoparticles are supported on the carbon carrier. As a result, the water electrolyzer can be made compact. Further, it is possible to reduce the power consumption per unit area.

A structure in which the anode catalyst layer 11 and the cathode catalyst layer 21 are bonded to the electrolyte membrane 5 so as to face the electrolyte membrane 5 is called a membrane electrode assembly (MEA) 8. The anode catalyst layer 11 of the anode electrode 10 and the cathode catalyst layer 21 of the cathode electrode 20 are electrically connected by the external circuit 7.

When a cation exchange membrane is used, water is supplied to the anode electrode 10 side in the water electrolyzer 1. Pure water is usually used. Water is electrolyzed mainly in the anode catalyst layer 11 of the anode electrode 10 to generate hydrogen ions and oxygen. In the water electrolyzer 1 configured as described above, oxygen gas is discharged from the anode electrode 10 through the gas flow path 14 of the separator 13. The generated hydrogen ions move to the cathode catalyst layer 21 via the electrolyte membrane 5 having ionic conductivity. On the other hand, the generated electrons move to the cathode catalyst layer 21 via the external circuit 7. The hydrogen ions and electrons that reach the cathode electrode 20 become hydrogen gas in the cathode catalyst layer 21. Oxygen gas and hydrogen gas are produced by these series of reactions.

The electrolyte membrane 5 is not particularly limited as long as it is a membrane made of a material capable of transporting ions and not exhibiting electron conductivity. Preferable examples include polyperfluorosulfonic acid resin, sulfonated polyether sulfonic acid resin, sulfonated polyimide resin, sulfuric acid-doped polybenzimidazole and the like.

Hereinafter, the catalyst layer used as the anode catalyst layer 11 will be described in detail. FIG. 4 shows a schematic partially enlarged view of the catalyst layer according to the first embodiment. The Ru-based nanoparticle coupling catalyst 3 according to the first embodiment is composed of a capsule-shaped catalyst 30, and is in contact with the ionic conductor 4 mainly on the outer surface of the capsule-shaped catalyst 30. The capsule-shaped catalysts 30 are brought into contact with each other and / or fused to each other to ensure electron conductivity. However, in the example of FIG. 4, the capsule-shaped catalysts 30 arranged on one surface are shown for convenience of explanation. , In the figure, the capsule-shaped catalysts 30 are not necessarily bonded and / or fused to each other.

FIG. 5 shows a schematic view of the capsule-shaped catalyst 30 of the first embodiment, and FIG. 6 shows a schematic perspective view of the VI-VI cutting line of FIG. As shown in FIGS. 5 and 6, the capsule-shaped catalyst 30 of the first embodiment has a network-like skeleton 31 having a substantially spherical outer shell, and the inside thereof has a hollow structure 32. The network-like skeleton 31 has a network-like structure in which metals are fused to each other, and has electron conductivity.

A large number of voids 33 are formed in the network-like skeleton 31. The void 33 is formed so as to communicate the inside and the outside of the capsule-shaped catalyst that defines the contour. The porosity of the reticulated skeleton 31 is not particularly limited. As long as the network skeleton can be maintained and electron conductivity can be ensured, it can be appropriately designed according to the application and required needs. In the case of applications where the amount of catalyst is required, for example, the void can be set to about 1%. Further, when the strength of the network-like skeleton is high due to the structure, for example, the void can be set to about 90%.

The thickness of the outer shell of the capsule-shaped catalyst 30 is not particularly limited, but is preferably 1 nm or more and 50 nm or less. By setting the thickness of the capsule-shaped catalyst 30 to 1 nm or more, structural defects can be suppressed and stable production can be performed. The shape of the Ru-based nanoparticle connecting 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, it can have an ellipsoidal shape, a cylindrical rod shape as in the third embodiment described later, a sheet shape as in the fifth embodiment described later, or a spiral shape. Further, it may be composed of a single type, or may be configured by fusing a plurality of two or more types.

The material of the Ru-based nanoparticle linking catalyst 3 can form a sintered body, and any metal-based nanoparticles containing a metal containing ruthenium at least in a part thereof can be used without limitation. A preferred example is Ru alone, a nanoparticle ligation catalyst. Further, a Ru-based nanoparticle linking catalyst containing a metal other than ruthenium may be used. As the other metal, conventionally known metals can be used. For example, platinum, cobalt, nickel, palladium, iron, silver, gold, copper, iridium, molybdenum, rhodium, chromium, tungsten, manganese, these metal compounds, metal oxides, and alloys containing two or more of these metals. Examples include fine particles composed of. Among these, ruthenium alone, ruthenium-platinum alloy, ruthenium-cobalt alloy, ruthenium-nickel alloy, ruthenium-iron alloy, ruthenium-platinum-iron alloy, ruthenium-platinum-iridium alloy, ruthenium-platinum-palladium alloy, etc. Ruthenium alloys are often used. Examples thereof include ruthenium-iron-nickel alloy, ruthenium-iridium alloy, ruthenium-palladium alloy, ruthenium-rodium alloy and the like. As the anode catalyst layer 11, a Ru-based nanoparticle linking catalyst may be used, and may be mixed with other metal nanoparticle linking catalysts.

The structure of the Ru-based nanoparticle linking catalyst 3 is not particularly limited, but a preferable structure is an fcc structure or an hcp structure (hexagonal close-packed). From the viewpoint of catalytic activity, it is preferable to have an fcc structure. The capsule-shaped catalyst 30 constituting the anode catalyst layer 11 may be used alone or in combination of two or more.

The particle size of the capsule-shaped catalyst 30 is not particularly limited, and can be appropriately selected depending on the intended use. 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-shaped catalyst 30 is usually 10 nm or more. In the anode catalyst layer 11, a plurality of anode catalyst layers having different particle sizes may be mixed.

The thickness of the catalyst layer can be appropriately designed according to the application, but it is preferably thin from the viewpoint of improving the efficiency of proton conductivity. Although it may vary depending on the type of the water electrolyzer used and the type of catalyst, the thickness of the anode catalyst layer 11 and the cathode catalyst layer 21 of the stack type water electrolyzer is preferably 10 μm or less. From the viewpoint of improving the efficiency of proton conductivity, the thickness of the catalyst layer is preferably 2 μm or less, more preferably 0.5 μm or less.

The ionic conductor 4 may be any conventionally known one as long as it exhibits ionic conductivity. When a cation exchange membrane is used, a cation conductor is used. In this case, a proton conductor that conducts hydrogen ions is usually used. On the other hand, when an anion exchange membrane is used, an anion conductor is used. In this case, a hydroxide ion conductor that conducts hydroxide ions is usually selected.

As the ionic conductor 4, a resin having an ionic conductive group or the like can be preferably used. For example, a polymer in which a sulfonic acid group or an anion exchange group is introduced into a fluorocarbon-based or hydrocarbon-based 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 exemplified. Examples of the acidic functional group include a sulfonic acid group, a sulfo group, a sulfonyl group, a phosphoric acid group and the like, and examples of the zirconium compound include zirconium sulfate, zirconium sulfophenylphosphonate, zirconium phosphate, zirconia sulfate and the like. .. Examples of the polymer having a sulfonic acid group include perfluorosulfonic acid polymers (Nafion (registered trademark), Flemion (registered trademark), Aciplex (trade name), etc.), SPECS: polyether sulfone, SPEEK: sulfonated polyether. Etherketone, SPEK: Sulfonated polyetherketone and the like can be exemplified.

The content of the ionic conductor in the catalyst layer is not particularly limited as long as the ionic conductivity can be ensured and the electric resistance value does not become too large. The catalyst layer may contain other components such as a binder other than the ionic conductor.

The capsule-shaped catalyst 30 has electron conductivity because the metals are fused or in contact with each other on the surface of the capsule. The electron conductivity between the capsule and other capsules is as follows: (1) a method of ensuring electron conductivity by bringing the capsule-shaped catalysts 30 into contact with each other, and (2) fusing the capsule-shaped catalysts 30 with each other between particles. Such a method and / or (3) a method of adding another conductive particle in order to assist the conductivity between the particles of the capsule-shaped catalyst 30 can be exemplified. As the method (1), a method of applying appropriate pressure from above and below in the thickness direction when forming the membrane electrode assembly can be exemplified. It is preferable to hot press at an appropriate temperature. As the method (2), a method of forming the capsule so as to have a desired shape during the sintering process described later, or a method of fusing the particles of the capsule-shaped catalyst 30 at the stage of forming the sintered body. An example is a method of performing the treatment by contacting the particles. 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 a suitable particle size so as not to hinder gas diffusion. For example, particles having a particle size smaller than that of the capsule-shaped catalyst 30 and porous carbon particles having excellent gas flowability can be mentioned. The above (1) to (3) can be used alone or in combination.

Next, an example of the method for producing the Ru-based nanoparticle-linked catalyst layer of the first embodiment will be described. However, the Ru-based nanoparticle-linked catalyst layer of the present invention can be produced by various methods, and is not limited to the following production methods.

The catalyst layer according to the first embodiment is manufactured through the following steps. That is, the step (a) of forming a mold having a desired shape and having a first polarity, and the mold surface having a second polarity opposite to the first polarity and containing catalyst nanoparticles. The step (b) of adsorbing or in-situ growing the metal nanoparticles to be produced, the step (c) of obtaining the Ru-based nanoparticles linking catalyst 3 by sintering, and the contact site with the Ru-based nanoparticles linking catalyst 3. It includes the step (d) of incorporating the ionic conductor having. As the metal nanoparticles, gold storage nanoparticles containing ruthenium are used. The ionic conductor in step (d) is at least one of the following (i) to (iii).
(I) A component contained in the mold incorporated in the step (a).
(Ii) It is obtained by converting the component contained in the template as a precursor after the step (c).
(Iii) It is introduced by adding a new step after the step (c).

[Step (a)]
First, an aqueous dispersion of pretemplate particles 34 (see FIG. 7) is prepared. Suitable materials for the pretemplate particles 34 include silica (SiO ₂ ), titanium oxide (TiO ₂ ), magnesium fluoride (MgF ₂ ), aluminum fluoride (AlF ₃ ), lithium fluoride (LiF), and sodium fluoride. (NaF), Aluminum Oxide (Al ₂ O ₃ ), Zirconia Oxide (ZrO ₂ ), Niobide Oxide (Nb ₂ O ₅ ), Indium Tin Oxide (ITO), Zinc Oxide (ZnO), Tin Oxide (SnO ₂ ), Examples thereof include inorganic materials such as ceria (CeO ₂ ), yttrium oxide (Y ₂ O ₃ ), bismuth oxide (Bi ₂ O ₃ ), apatite, and glass. The pretemplate particles 34 may be made of a single material or may be particles obtained by mixing a plurality of materials. Further, particles obtained by kneading, mixing, granulating and classifying two or more kinds of materials in advance may be used.

The method for preparing the pre-template particles 34 is not particularly limited, but for example, rolling granulation, fluidized layer granulation, stirring granulation, crushing / crushing granulation, compression granulation, extrusion granulation, fusion granulation, and mixing. Granulation can be performed using physical granulation methods such as granulation, spray-cooled granulation, spray-drying granulation, precipitation / precipitation granulation, freeze-drying granulation, suspension coagulation granulation, and drop-cooled granulation. .. Classify as necessary. If the premolded particles 34 are commercially available, they may be used.

The range of the particle size of the pretemplate particles 34 is not particularly limited, but is usually about 10 nm to 10 μm. If the particle size exceeds 10 μm, the pretemplate particles 34 may not be dispersed in the solvent. The shape of the premold particles 34 is not particularly limited, but is usually spherical or substantially spherical. As described above, the shape of the hollow capsule-shaped catalyst 30 can be adjusted by the shape of the premold particles 34.

The surface of the pretemplate particles 34 is then modified. Specifically, an aqueous dispersion of template particles 35 (see FIG. 8) coated with a coating layer (not shown) having the first polarity is prepared. Since the mold particles 35 are coated with a coating layer, the mold particles 35 have a larger particle size than the pre-mold particles 34. The thickness of the coating layer is not particularly limited and can be appropriately set as long as it does not deviate from the gist of the present invention. The coating layer does not necessarily have to be coated over the entire surface of the premolded particles 34, and there may be uncoated areas.

The method of coating the coating layer on the premold particles 34 is not particularly limited, but the method of coating by electrostatic bonding is convenient. When the pretemplate particles 34 are negatively charged particles, a positively charged coating layer can be coated. Further, when the pretemplate particles 34 are positively charged particles, the negatively charged coating layer can be coated. It is also possible to coat the negatively charged coating layer with a more positively charged coating layer.

The coating layer is not particularly limited as long as the template particles 35 can exhibit the first polarity, but preferred 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 positively charged ionic polymer generally include those having a positively charged or capable functional group such as a quaternary ammonium group and an amino group. Specifically, polyethyleneimine (PEI), polyallylamine hydrochloride (PAH), polydiallyldimethylammonium chloride (PDDA), polyvinylpyridine (PVP), polylysine and the like. On the other hand, examples of the ionic polymer having a negative charge include those having a negative charge or a functional group capable of carrying a negative charge such as sulfonic acid, sulfuric acid, and carboxylic acid. Specifically, polystyrene sulfonic acid (PSS), polyvinyl sulfuric acid (PVS), dextran sulfuric acid, chondroitin sulfuric acid, polyacrylic acid (PAA), polymethacrylic acid (PMA), polymaleic acid, polyfumaric acid and the like. Through these steps, the mold 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 coagulate and settle in water. The upper limit is not particularly limited, but is usually +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. The lower limit is not particularly limited, but is usually -80 mV or more.

[Step (b)]
Next, in order to form the network-like skeleton 31 of the capsule-shaped catalyst 30 on the surface of the template particles 35, the material of the metal nanoparticles is adsorbed or grown on the spot. As a result, the adhesion type catalyst particles 36 (see FIG. 9) are obtained. Specifically, a solution in which a material for forming the capsule-shaped catalyst 30 is dissolved is added to a uniform dispersion of the template particles 35, and these are adsorbed on the template particles 35 or grown on the spot. The polarity of the surface of the metal nanoparticles and template particles 35 to be added is opposite to that of the surface. That is, as the metal-based nanoparticles, those having a second polarity opposite to the first polarity on the surface of the template particles 35 are used.

The shape of the metal nanoparticles is not particularly limited, and an amorphous powder, a flat powder, a spherical powder, a rod-shaped powder, or the like can be appropriately selected depending on the application and purpose. When the metal nanoparticles are blended, those having a plurality of shapes may be mixed. In addition, the metal nanoparticles may contain components that are removed in the sintering step described later.

The average particle size of the metal 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 the catalytic activity per mass. The average particle size of the metal 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 the catalytic activity per mass. The particle size of the catalyst nanoparticles is preferably a material having high catalytic ability even if it is small. As a preferable material of the catalyst nanoparticles, the material of the capsule-shaped catalyst 30 described above can be mentioned. The same applies to the preferable range of the average particle size of the metal nanoparticles other than the catalyst nanoparticles.

[Step (c)]
Subsequently, the adherent catalyst particles 36 are converted into a sintered body. As a result, a fusion-type network skeleton (see FIG. 10) is obtained by adsorption or in-situ growth and fusion. Examples of the method for obtaining the sintered body include a hydrothermal reaction and an alcohol thermal reaction. After firing, the mold particles 35 are eluted to remove the mold particles 35, and a hollow capsule-shaped catalyst 30 as shown in FIG. 5 is obtained.

The method of sintering treatment is not particularly limited as long as a metal-based network treatment can be realized, but it is preferably performed by a hydrothermal reaction or an alcohol thermal reaction. For the hydrothermal reaction and the alcohol thermal reaction, it is preferable to carry out a subcritical treatment, and it is particularly preferable to carry out a supercritical treatment. 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 adherent catalyst particles 36. In the case of silica fine particles having a particle size of about 300 nm, for example, the temperature is 300 to 400 ° C., 10 to 40 MPa, the reaction time is 1 to 3 hours, and the like. As a method of forming a superlattice structure in the capsule-shaped catalyst 30, a method of impregnating catalyst nanoparticles with iron and performing an alcohol thermal reaction can be exemplified.

The Ru-based nanoparticle linking catalyst 3 is obtained by the above steps. In the first embodiment, in order to make the inside of the obtained capsule-shaped catalyst 30 hollow, the mold is removed using an aqueous NaOH solution or the like.

[Step (d)]
It has a step (d) of incorporating an ionic conductor in contact with at least a part of the Ru-based nanoparticle linking catalyst 3. As the ionic conductor, an ionic conductive binder such as an inorganic particle or a polymer as described above, or a composite material thereof is preferably used. Examples of the method of incorporation include a method of adding the ionic conductor 4 to the Ru-based nanoparticle linking catalyst 3 and kneading the mixture, and a method of heating and melting the ionic conductor 4 and entwining the ionic conductor 4 with the Ru-based nanoparticle linking catalyst 3. The step (d) is not limited to the case where the step (d) is carried out after the step (c), and may be incorporated in the steps (i) and (ii) described above. Moreover, these can be used together arbitrarily.

By the way, in the conventional method using a metal nanoparticle catalyst (for example, 2 to 3 nm) as an anode catalyst supported on a carbon carrier, as shown in FIG. 28, water is electrolyzed to generate oxygen gas, electrons, and hydrogen ions. It is occurring. The carbon particles carry a nanoparticulate metal catalyst to increase the effective surface area of the metal catalyst, and at the same time, disperse the metal catalyst particles so as not to aggregate and play a role of electron conduction. However, the carbon carrier is also a factor that inhibits gas diffusion. In fact, in the high current density region of the catalyst layer, the gas diffusion rate is slower than the reaction rate, and there is a problem that the activity decreases due to the gas diffusion rate-determining. Further, since the interface between the carbon carrier and the catalyst particles does not contribute to the reaction, there is a problem that the effective surface area of the catalyst nanoparticles is reduced by that amount.

On the other hand, according to the first embodiment, by using the Ru-based nanoparticles connecting catalyst 3 in either the anode catalyst layer 11 or the cathode catalyst layer 21, the nanoparticles are supported on the carbon carrier as compared with the catalyst layer. It is possible to reduce the thickness of the film. Therefore, the mass transfer resistance of the gas can be reduced. Moreover, since the metal nanoparticles have a structure in which they are connected to each other, voids can be formed while maintaining conductivity. In addition, the mechanical strength can be increased. As a result, the gas diffusivity is dramatically improved.

Further, by using the Ru-based nanoparticle coupling catalyst 3 for the anode catalyst layer 11, the oxygen evolution reaction can be efficiently promoted and the catalytic activity can be enhanced as compared with the case where a metal such as Pt is used. Further, the surface area can be remarkably increased by using the nanoparticle connecting catalyst having a network structure having voids. Therefore, since the catalyst efficiency per unit mass can be improved, the amount of precious metal used can be reduced, and the cost can be reduced. In addition, since it is highly active, it can be expected to reduce external power consumption.

When a carbon carrier is used for the anode catalyst layer 11 and the cathode catalyst layer 21, deterioration due to carbon corrosion in high potential operation becomes a problem, but according to the Ru-based nanoparticle coupling catalyst of the first embodiment, the carrier is free. Since it can be used in, durability can be improved. It also enables high potential operation. The Ru-based nanoparticle linking catalyst 3 of the present invention can be used without a carbon carrier, but it can also be used with a carbon carrier.

According to the method for producing a Ru-based nanoparticle-linked catalyst layer of the first embodiment, the particle size and hollow diameter of hollow catalyst particles can be easily adjusted by controlling the particle size, particle size distribution, and particle shape of the template particles. Can be controlled. Further, by including iron or the like, a capsule-shaped catalyst having a superlattice structure can be easily produced. Further, since the process of adding and contacting the ionic conductor after the production of the capsule-shaped catalyst is adopted, there is an advantage that the degree of freedom in the manufacturing process of the capsule-shaped catalyst and the degree of freedom in material selection are high.

[Second Embodiment]
Next, an example of the Ru-based nanoparticle-linked catalyst layer different from the first embodiment will be described. The Ru-based nanoparticle-linked catalyst layer of the second embodiment is different from the Ru-based nanoparticle-linked catalyst layer of the first embodiment in that an ionic conductor is mainly arranged inside the capsule-shaped catalyst 30, but the following The basic structure and manufacturing method other than those described in the above are the same as those in the first embodiment. In the following description, the same element members as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

FIG. 11 shows a schematic partially enlarged view of the catalyst layer according to the second embodiment. In the anode catalyst layer 11 according to the second embodiment, the ionic conductor 4 is mainly contained in the hollow structure 32 and the void 33 (see FIG. 4) of the capsule-shaped catalyst 30 of the Ru-based nanoparticle connecting catalyst 3.

The method for producing the catalyst layer according to the second embodiment includes steps (a) to (d) as in the first embodiment described above, and the ion conductor of the step (d) is, for example, a step. It is a component constituting the pre-template particles and / or the template particles incorporated by (a).

In order to enclose the ionic conductor 4 of the step (d) in the capsule-shaped catalyst 30, at least one of the pre-template particles and / or the components of the template particles of the step (a) is used as an ionic conductor (method (i). )). Preferred examples of pretemplate particles include inorganic proton conductors such as zirconium compounds having acidic functional groups such as zirconium sulfate, zirconium sulfophenylphosphonate, zirconium phosphate and zirconia sulfate, and inorganic anion conduction such as layered double hydroxides. The body can be illustrated. Further, as a preferable example when the ionic conductor 4 is used as a component of the template particles incorporated in the step (a), a sulfonic acid group or an anion exchange is carried out in the fluorocarbon-based or hydrocarbon-based polymer exemplified in the first embodiment. Examples include polymers into which groups have been introduced.

In order to encapsulate the ionic conductor 4 of the step (d) in the capsule-shaped catalyst 30, the template of the step (a) can be used as a precursor and converted after the sintering treatment of the step (c) (method (ii). )). For example, a method of introducing an ionic conductive functional group (acidic functional group, anionic functional group) into a template can be exemplified.

Further, in order to enclose the ionic conductor of the step (d) in the capsule-shaped catalyst 30, a method of adding a new ionic conductor after the step (c) and introducing the ionic conductor into the capsule-shaped catalyst 30 can be exemplified (). Method (iii)). This method is particularly effective when the porosity of the capsule-shaped catalyst 30 is large. The methods (i) to (iii) can be arbitrarily combined.

In the case of the method (i), the sintering process of the step (c) sets the conditions under which the functional groups of the ionic conductor are not broken. Ensuring the electron conductivity and the ionic conductivity between the particles of the capsule-shaped catalyst 30 may be performed by hot pressing or the like when manufacturing the membrane electrode assembly. Further, during the sintering process, the catalyst nanoparticles may be melted and connected between the particles at the contact portion between the particles of the capsule-shaped catalyst 30. It is preferable that the ionic conductors are in contact with each other and / or are bonded to each other over the plurality of capsule-shaped catalysts 30 so that the ionic conductivity can be ensured between the particles.

In FIG. 11, an example in which the ionic conductor 4 is mainly arranged inside the capsule-shaped catalyst 30 has been given, but the ionic conductor 4 is a Ru-based nano in combination with the first embodiment and the second embodiment. It can also be formed both inside and outside the particle linking catalyst 3.

According to the anode catalyst layer 11 of the second embodiment, the following effects can be obtained in addition to the effects of the first embodiment. That is, by encapsulating the ionic conductor 4 inside the capsule-shaped catalyst 30, the anode catalyst layer 11 can be downsized with high efficiency. Further, according to the method for producing the anode catalyst layer 11 of the second embodiment, the following effects and the like can be obtained in addition to the effects of the first embodiment. That is, according to the method (i), there is an advantage that the step of bringing the ionic conductor into contact with the capsule-shaped catalyst can be omitted after the step (c), and the manufacturing step can be shortened. Further, according to the method (ii), since the sintering treatment is performed before the introduction of the ionic conductive functional group, the sintering treatment conditions and material choices are higher than those of the method (i). There is a merit.

[Third Embodiment]
The Ru-based nanoparticle linking catalyst layer of the third embodiment is different from the above-described embodiment using the capsule-shaped catalyst 30 in that the Ru-based nanoparticle linking catalyst 3 is composed of a rod-shaped catalyst, but is basic. The configuration is the same as that of the second embodiment.

FIG. 12 shows a partially enlarged view schematically showing the anode catalyst layer 11 of the third embodiment. As shown in FIG. 12, the anode catalyst layer 11 has a rod-shaped catalyst 40 and an ionic conductor 4.

As shown in FIG. 12, the rod-shaped catalyst 40 forms a substantially tubular network-like skeleton 41, and an ionic conductor 4 is arranged inside the rod-shaped catalyst 40. The network-like skeleton 41 has a network-like structure in which metals are fused to each other, and has electron conductivity.

A large number of voids 43 are formed in the network-like 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. The preferable range of the porosity of the reticulated skeleton 41 is the same as that of the first embodiment. In the example of FIG. 12, one rod-shaped anode catalyst layer 11 is illustrated, but in reality, a sheet-like structure is formed by a plurality of rod-shaped catalysts 40.

The thickness constituting the outer shell of the rod-shaped catalyst 40 is not particularly limited, but is preferably 1 nm or more and 50 nm or less. By setting the thickness of the rod-shaped catalyst 40 to 1 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 realize good ionic conductivity in the catalyst layer, the ionic conductor 4 includes not only the inside of the rod-shaped catalyst 40 but also the voids 43 formed in the network-like skeleton 41 of the rod-shaped catalyst 40 and the rod-shaped catalyst 40. It is preferable that the rod is continuously formed on the outside of the rod.

As the preferred material of the rod-shaped catalyst 40 and the ionic conductor 4, the same materials as those in the first embodiment can be exemplified. The length of the rod-shaped catalyst 40 and the particle size of the cut end face 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 and a structure in which the rod-shaped catalysts 40 are randomly arranged can be exemplified. The rod-shaped catalyst may be used in a single layer or in a plurality of layers. When a plurality of layers are used, they may be arranged so as to extend in different directions between the layers 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 electrolyte membrane 5 can be horizontal orientation, vertical orientation, random orientation, or the like. It is also possible to use a blend of the rod-shaped catalyst 40 and the capsule-shaped catalyst 30 of the first embodiment.

According to the anode catalyst layer 11 of the third embodiment, the same effect as that of the above-described embodiment can be obtained. Further, by using the rod-shaped catalyst 40 linked with nanoparticles, it is possible to increase the mechanical strength while increasing the surface area that can be used as the catalyst. Moreover, since it is connected in a rod shape, more stable electron conductivity can be ensured.

[Fourth Embodiment]
The third embodiment of the Ru-based nanoparticle linking catalyst layer of the fourth embodiment is in that the Ru-based nanoparticle linking catalyst 3 is a rod-shaped catalyst and an ionic conductor is disposed outside the rod-shaped catalyst. Although different from the Ru-based nanoparticle-linked catalyst layer of the form, the basic structure and manufacturing method other than those described below are the same as those of the third embodiment.

The catalyst layer according to the fourth embodiment is arranged outside the rod-shaped catalyst of the Ru-based nanoparticle linking catalyst so that the ionic conductor is mainly entangled with the Ru-based nanoparticle linking catalyst. The ionic conductor of step (d) can be easily manufactured by incorporating it after step (c) in order to dispose it on the outside inside the rod-shaped catalyst.

According to the Ru-based nanoparticle-linked catalyst layer of the fourth embodiment, in addition to the same effect as that of the third embodiment, the ionic conductor is incorporated after the step (c), so that the process margin of the sintering process or the material of the mold is used. It has the advantage of increasing selectivity.

[Fifth Embodiment]
The Ru-based nanoparticle linking catalyst layer of the fifth embodiment is different from the above-described embodiment in that the Ru-based nanoparticle linking catalyst is a sheet-like catalyst, but has a basic structure and production other than those described below. The method is the same as that of the above-described embodiment.

FIG. 13 shows a schematic view of the sheet-shaped anode catalyst layer 11 of the fifth embodiment. In the anode catalyst layer 11 according to the fifth embodiment, the Ru-based nanoparticle connecting catalyst and the ionic conductor are continuously arranged in the plane and in the thickness direction in the shape of a sheet 44. That is, the Ru-based nanoparticle-linked catalyst composed of a sheet-like catalyst has a network-like sheet structure, and the metals are fused to each other to have electron conductivity. Then, the ionic conductors are dispersed and arranged so as to come into contact with the sheet-shaped catalyst. The thickness of the sheet-shaped catalyst is not particularly limited and may be appropriately designed according to the application and required performance, but is preferably 10 μm or less, more preferably 2 μm or less, still more preferably 0.5 μm or less. By reducing the thickness of the sheet-shaped catalyst, structural defects can be suppressed and stable production can be performed.

As a method for obtaining a sheet-shaped Ru-based nanoparticle-linked catalyst, a film or sheet whose surface has the first polarity is used as a template, and the catalyst nanoparticles having the second polarity are impregnated therein to obtain metal nanoparticles. It is obtained by adsorption or in-situ growth and sintering. The film or sheet having the first polarity on the surface is not limited as long as it does not deviate from the gist of the present invention, but a non-woven fabric can be exemplified as a preferable example.

The constituent material of the non-woven fabric is not particularly limited as long as it does not deviate from the gist of the present invention, but silica fiber, zirconia fiber and the like can be exemplified as preferable examples. In this case, the non-woven fabric is used as a template, and after surface treatment is performed so that these non-woven fabrics have the first polarity, metal nanoparticles containing the catalyst nanoparticles having the second polarity are adsorbed or on the spot. It may be grown and sintered. The ion conductor 4 is a method of incorporating an ionic conductive functional group or the like into a silica fiber, a zirconia fiber or the like in advance (i), and / or a method of incorporating an ionic conductive functional group into these fibers after a sintering treatment (ii). Can be exemplified.

Further, as the non-woven fabric, it is also possible to use a material that can be sintered or removed after the sintering treatment. In this case, a catalyst layer is obtained by entwining the ionic conductor 4 with the obtained sheet-shaped Ru-based nanoparticle-linked catalyst.

According to the method of the fifth embodiment, there is an advantage that the step of forming the catalyst layer can be simplified. Further, since the Ru-based nanoparticle connection catalyst is constructed in the form of a sheet, the electron conduction efficiency and the surface area can be improved. It is also possible to reduce the thickness.

[Sixth Embodiment]
Next, a water electrolysis device different from the above embodiment will be described. FIG. 14 shows a schematic view of an example of a main part of the water electrolyzer according to the sixth embodiment. The water electrolyzer 2 according to the sixth embodiment includes an aqueous electrolyte solution 50, an electrolytic cell 51, an anode electrode 52, a cathode electrode 53, a partition wall 54, an external circuit 55, and the like.

As the electrolyte aqueous solution 50, an alkaline aqueous solution or an acidic aqueous solution is used. When a predetermined voltage is applied between the anode electrode 52 and the cathode electrode 53, a current flows between both electrodes and the electrochemical reaction proceeds. On the anode electrode 52 side, water is oxidized by an oxidation reaction to generate oxygen gas. On the other hand, a reduction reaction occurs on the surface of the cathode electrode 53 to generate hydrogen. The partition wall 54 plays a role of preventing a reverse reaction of the generated gas between the anode electrode 52 and the cathode electrode 53.

As the electrolyte aqueous solution 50, an alkaline aqueous solution or an acidic aqueous solution in which the electrolyte is dissolved is used. Examples of the electrolyte include potassium hydroxide, sodium hydroxide, sulfuric acid, nitric acid, perchloric acid, sodium sulfate, sodium nitrate, sodium perchlorate and the like. Examples of the cation of the electrolyte contained in the aqueous electrolyte solution 50 include protons, alkali metal ions, alkaline earth metal ions and the like. Further, examples of the anion include hydroxide ion, sulfate ion, nitrate ion and the like.

As shown in FIG. 14, the anode electrode 52 and the cathode electrode 53 are immersed in the aqueous electrolyte solution 50 and connected to the external circuit 55. Oxygen is generated on the anode electrode 52 side, and hydrogen is generated on the cathode electrode 53 side.

The anode catalyst layer 11 of the first to fifth embodiments can be preferably applied to at least the surface layer of the anode electrode 52. The anode electrode 52 itself may be made of the anode catalyst layer 11, or the anode catalyst layer may be supported on a metal plate, a metal mesh, carbon, or the like.

The cathode electrode 53 is composed of a known conductor. The conductive material is not particularly limited as long as it is not decomposed in the aqueous electrolyte solution 50. For example, a platinum or nickel compound can be exemplified. It may be made of the same material as the anode electrode 52.

According to the water electrolysis apparatus according to the sixth embodiment, since the Ru-based nanoparticle coupling catalyst is used, the same effect as that of the first embodiment and the like can be obtained.

[7th Embodiment]
Next, an embodiment in which the Ru-based nanoparticle coupling catalyst is applied to a fuel cell will be described. FIG. 15 is a schematic cross-sectional view showing an example of a main part of the polymer electrolyte fuel cell according to the seventh embodiment. The polymer electrolyte fuel cell 101 includes a cell 6 including a polymer electrolyte membrane 5 having ionic conductivity, an anode unit 15 to which a fuel gas such as hydrogen is supplied, and a cathode unit 25 to which oxygen is supplied. It also has an external circuit 7 and the like. Usually, the battery is configured by stacking cells 6 according to the required output.

In the anode unit 15, the anode catalyst layer 11, the gas diffusion layer 12, and the separator 13 are arranged in this order from the solid polymer electrolyte membrane (hereinafter, also referred to as “electrolyte membrane”) 5 side, and the cathode unit 25 is the cathode catalyst layer. 21, the gas diffusion layer 22, and the separator 23 are arranged in this order from the electrolyte membrane 5 side. In the seventh 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 need only be able to contact the gas, the electrolyte and the catalyst layer at the same time, and the gas diffusion layers 12 and 22 do not necessarily have to be used. That is, it is also possible that the anode catalyst layer is composed of only the anode catalyst layer 11 and / or the cathode catalyst layer 21. Further, 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 8. The external circuit 7 is electrically connected to the anode catalyst layer 11 of the anode unit 15, the cathode catalyst layer 21 of the cathode unit 25, and the like.

In the polymer electrolyte fuel cell 101 configured as described above, in the anode unit 15, a reducing gas such as hydrogen is supplied from the gas flow path 14 of the separator 13 to the anode catalyst layer 11 via the gas diffusion layer 12. Will be done. On the other hand, in the cathode unit 25, 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 via the gas diffusion layer 22.

In the case of the cation exchange type in which hydrogen gas is used as the reducing gas and oxygen gas is used 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 via the electrolyte membrane 5 having ionic conductivity. On the other hand, the generated electrons move to the cathode catalyst layer 21 via the external circuit 7. The hydrogen ions and electrons that reach the cathode unit 25 react with oxygen in the cathode catalyst layer 21 to generate water. That is, an oxygen reduction reaction occurs in the cathode catalyst layer 21. The water generated by the reduction reaction is discharged to the outside from the separator 23 of the cathode unit 25 or supplied to the electrolyte membrane 5. Electricity is supplied to the outside by these series of reactions.

The role of the electrolyte membrane 5 and suitable specific examples are the same as those in the above embodiment. Further, the Ru-based nanoparticle coupling catalyst of the anode catalyst layer 11 is also as described in the above embodiment.

According to the seventh embodiment, the surface area that can be used as a catalyst can be increased by using a Ru-based nanoparticle-linked catalyst in either the anode catalyst layer 11 or the cathode catalyst layer 21. In addition, conductivity can be ensured without using a carbon carrier. Therefore, since the thickness of the catalyst layer can be reduced, the gas diffusion distance can be reduced and the gas diffusion rate can be increased. Therefore, according to the present invention, the problem of gas diffusion rate-determining, which has been a problem in the high current density region of the catalyst layer using the conventional carbon carrier, can be solved and high output can be realized. In addition, there is an advantage that it is not affected by carbon corrosion, which is a problem when carbon is used as a carrier. In the seventh embodiment, an example of application to a polymer electrolyte fuel cell as a catalyst layer has been described, but it can be suitably applied to various fuel cells. As a result, the performance as a fuel cell can be improved. In addition, CO poisoning resistance can be enhanced as compared with the conventional example in which Pt nanoparticles are supported on a carbon carrier. As a result, the durability as a fuel cell catalyst can be remarkably improved.

[8th Embodiment]
Next, an embodiment using a Ru-based nanoparticle linking catalyst as a hydrogenation catalyst for reforming methane gas into hydrogen gas will be described.
As the _{catalyst for advancing the reaction of CH 4} + 2H ₂ O → CO ₂ + 4H ₂ , the Ru-based nanoparticle linking catalyst described in the above embodiment can be used. As the apparatus used for hydrogenation of methane, a known one can be used as long as the Ru-based nanoparticle coupling catalyst is arranged at a position where the hydrogenation reaction of methane gas can be promoted.

FIG. 16 is a schematic view showing an example of the hydrogenation apparatus for methane gas according to the eighth embodiment. The methane gas hydrogenator 201 has a housing 60, a gas supply port 61, a gas discharge port 62, a housing internal space 63, and the like. The housing internal space 63 is filled with the Ru-based nanoparticle connecting catalyst 3. Water vapor and methane gas are sent from the gas supply port 61 into the housing internal space 63. Then, methane gas and water react with each other by the Ru-based nanoparticle connecting catalyst 3 filled in the housing internal space 63, and finally carbon dioxide and hydrogen are generated and recovered at the gas discharge port 62. Instead of the method of filling the housing internal space 63 with the Ru-based nanoparticle connecting catalyst 3, it may be supported on an inner wall installed inside the housing. Further, the sheet formed by using the Ru-based nanoparticle connecting catalyst 3 may be wound and housed in the housing internal space 63.

According to the methane gas hydrogenation catalyst according to the eighth embodiment, it is possible to provide a methane hydrogenation catalyst having excellent durability and capable of increasing the catalyst efficiency even without a carbon carrier.

The first to eighth embodiments can be arbitrarily combined. The water electrolyzer and the fuel cell may be integrated into a switchable device.

<< 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)
Template particles having a positive zeta potential were prepared by the following method. First, 0.16 g of silica particles (0.30 μm in diameter) as pretemplate particles and 5 mL of deionized water were placed in a 30 mL beaker to disperse the silica particles.

Next, 12.0 g of poly (diallyldimethylammonium chloride) (hereinafter abbreviated as "PDDA") and 19 g of deionized water were placed in a tube for a centrifuge. This tube was irradiated with ultrasonic waves for 10 minutes. The PDDA was dissolved. In addition, the beaker in which the silica particles were dispersed was irradiated with ultrasonic waves for 10 minutes, then the two solutions were mixed, and the mixture was centrifuged with deionized water at 25 ° C. and a rotation speed of 10,000 rpm for 10 minutes. This was carried out, and the purification of discarding the supernatant liquid and performing washing was repeated three times. As a result, an aqueous dispersion of PDDA-coated silica particles (template particles) dispersed in deionized water was obtained. PDDA-coated silica particles are referred to as "PDDA / SiO _2- OH".

Next, Ru-based nanoparticle-adsorbed PDDA-coated silica particles were synthesized. Tetraethylene glucol (manufactured by Sigma-Aldrich) 100 mL, PDDA / SiO _2- OH aqueous dispersion obtained in the above step is placed in a 200 mL eggplant-shaped flask so that the dry mass of PDDA / SiO _{2 is 0.08 g.} In addition, water was removed by evaporation. Transfer the contents of the flask to a 200 mL three-necked flask, add 0.1612 g (0.40 mmol) of acetylacetonatoruthenium (III) and 0.1591 g (0.40 mmol) of acetylacetonato platinum (II), and stir for 24 hours. Was done. Then, 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. Then, the temperature was raised to 180 ° C. at 10 K / min, and the mixture was heated at 180 ° C. for 2 hours. After allowing to cool to room temperature, the step of discarding the brown supernatant solution and washing with ethanol was repeated 5 times. Then it dried. When the ratio of Ru and Pt was determined by ICP, it was _{Ru 7.1} Pt _1.

The ethanol dispersion of the obtained Ru-based nanoparticle-adsorbed PDDA-coated silica particles was prepared and redispersed by sonication for 10 minutes. 5 mL of the obtained dispersion was placed in a closed supercritical reaction vessel TSC-0011 (volume 11 mL) manufactured by Pressure Resistant Glass Industry Co., Ltd., and sealed with a torque wrench. The sealed reaction vessel was placed in an electric furnace preheated to 380 ° C., and heat-treated for 80 minutes under the condition of a pressure of about 30 MPa. Then, the reaction vessel was placed in a water tank and rapidly cooled. After leaving it to stand for 1 to 2 hours, the reaction vessel was opened, and the step of washing with ethanol using ultrasonic treatment was repeated 5 times, and then dried. The scanning electron microscope image of the obtained Ru-based nanoparticle coupling catalyst is shown in FIG. From the figure, it was confirmed that by supercritical treatment at high temperature and in a short time, aggregation of RuPt metal particles was suppressed, an intermetal network was formed, and a capsule-shaped Ru-based nanoparticle coupling catalyst was obtained.

Then, the silica template was dissolved and removed by dispersing in a 3M aqueous NaOH solution and stirring at 85 ° C. for 3 hours. Then, centrifugation (25 ° C., 6,000 rpm, 10 minutes) was performed several times to wash and dry.

It was confirmed from the ICP that the obtained Ru-based nanoparticle linking catalyst was hollow, had an average particle size of about 300 nm, and had an element ratio of Ru _6.9 Pt _1. Hereinafter referred to Ru-based nanoparticle coupling catalyst obtained in Example 1 and the connecting _Ru 7 _Pt 1 -180. Figure 18 shows transmission electron microscopic image of 100keV consolidated _Ru 7 _Pt 1 -180 (the Hitachi H8100 transmission electron microscope). From the figure, it can be seen that the silica particles of the core material are dissolved and removed. Further, it can be seen that the nanoparticles are fused to each other and have a nanoparticle connection structure having voids on the surface.

(Example 2)
Ru-based nanoparticles adsorption in the same manner as in Example 1 except that 0.0403 g (0.10 mmol) of acetylacetonatoruthenium (III) and 0.2784 g (0.71 mmol) of acetylacetonato platinum (II) were added. PDDA-coated silica particles were obtained, and then a Ru-based nanoparticle linking catalyst (average particle size: about 300 nm, hollow) was obtained. Hereinafter referred to Ru-based nanoparticle coupling catalyst obtained in Example 2 and the connecting _Ru 1 _Pt 1 -180. Ratio of Ru and Pt by ICP is, Ru-based nanoparticles adsorbed PDDA coated silica particles _Ru 1.1 Pt _1, connecting _Ru 1 _Pt 1 -180 was _Ru 1.1 Pt _1. Figure 19 shows a transmission electron micrograph of the consolidated _Ru 1 _Pt 1 -180 according to the second embodiment.

(Example 3)
Ru-based nanoparticle-adsorbed PDDA-coated silica particles were obtained in the same manner as in Example 1 except that the heating temperature at the time of synthesizing Ru-based nanoparticle-adsorbed PDDA-coated silica particles by the polyol method was changed to 230 ° C., and then Ru-based nanoparticles were obtained. A particle linking catalyst (average particle size: about 300 nm, hollow) was obtained. Hereinafter referred to Ru-based nanoparticle coupling catalyst obtained in Example 3 and the connecting _Ru 1 _Pt 1 -230. The ratio of Ru to Pt by ICP was Ru ₁ Pt _1.3 for Ru-based nanoparticle- _{adsorbed PDDA-coated silica particles and Ru 1} Pt _1.1 for Ru-based nanoparticle linkage catalyst. Figure 20 shows a transmission electron micrograph of the consolidated _Ru 1 _Pt 1 -230 according to the third embodiment.

(Comparative Example 1)
Pt / C (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., TEC10E50E, Pt: 46.6% by mass) was used as it was. It was confirmed that no connection structure between the particles was observed in the fine particles of Comparative Example 1.

(Comparative Example 2)
PtRu / C (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., TEC66E50, Pt: 32.6% by mass, Ru: 16.9% by mass) was used as it was. It was confirmed that no connection structure between the particles was observed in the fine particles of Comparative Example 2.
(Comparative Example 3)

For comparison, Pt-based nanoparticle-adsorbed PDDA-coated silica particles were synthesized. Tetraethylene glucol (manufactured by Sigma-Aldrich) 100 mL, PDDA / SiO _2- OH aqueous dispersion obtained in Example 1 was placed in a 200 mL eggplant-shaped flask so that the dry mass of PDDA / SiO _{2 was 0.08 g.} In addition, water was removed by evaporation. Transfer the contents of the flask to a 200 mL three-necked flask, add 0.15 g (0.42 mmol) of acetylacetonato iron (III) and 0.1512 g (0.38 mmol) of acetylacetonato platinum (II), and stir for 24 hours. Was done. Then, 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. Then, the temperature was raised to 230 ° C. at 10 K / min, and the mixture was heated at 230 ° C. for 2 hours. After allowing to cool to room temperature, the step of discarding the brown supernatant solution and washing with ethanol was repeated 5 times. Then it dried. When the ratio of Fe and Pt was determined by ICP, it was _{Fe 1} Pt _1.

The ethanol dispersion of the obtained Fe-based nanoparticle-adsorbed PDDA-coated silica particles was prepared and redispersed by sonication for 10 minutes. 5 mL of the obtained dispersion was placed in a closed supercritical reaction vessel TSC-0011 (volume 11 mL) manufactured by Pressure Resistant Glass Industry Co., Ltd., and sealed with a torque wrench. The sealed reaction vessel was placed in an electric furnace preheated to 330 ° C., and heat-treated for 160 minutes under the condition of a pressure of about 20 MPa. Then, the reaction vessel was placed in a water tank and rapidly cooled. After leaving it to stand for 1 to 2 hours, the reaction vessel was opened, and the step of washing with ethanol using ultrasonic treatment was repeated 5 times, and then dried. It was confirmed that the obtained Pt-based nanoparticle linking catalyst formed an intermetal network to obtain a capsule-shaped Pt-based nanoparticle linking catalyst.

XRD (RINT2000, manufactured by Rigaku) measurement (diffraction angle range: 2θ = 10 to 90 °, scan speed: 2θ = 1 ° / min) was performed on each of the powder samples of Examples 1 to 3 and Comparative Examples 1 and 2. went. The result is shown in FIG. Microparticles of Example 1, as shown in FIG. 21, connected _Ru 7 _Pt 1 -180 of Example 1, 2 [Theta] = 40 ° around the (111) peak of the plane Comparative Example 1, Comparative Example 2 platinum It is shifted to the higher angle side from the peak position of the (111) plane, and it can be seen that the structure is fcc-Ru rich.

Consolidated _Ru 1 _Pt 1 -180 of Example 2, it can be seen that the platinum (111) plane and the peak position of the comparison example 1 is a fcc-Pt-rich structure from a closer. On the other hand, in the fine particles of Example 3, the peak of the (111) plane near 2θ = 40 ° is shifted to a higher angle side than the peak position of the (111) plane of platinum, and the peak is the (111) plane and the peak of Comparative Example 2. Since the positions are close, it can be seen that they are alloyed. As shown in Examples 1 to 3, Ru-based nanoparticle-linked catalysts having different structures can be obtained by controlling the polyol reaction temperature and the charged composition ratio when producing the capsule catalyst.

[Evaluation of water electrolysis activity]
The Ru-based nanoparticle linking catalyst obtained in Example 1, the Pt / C particles of Comparative Example 1, and the Pt-based nanoparticle linking catalyst of Comparative Example 3 were subjected to an oxygen generation reaction as a water electrolytic anode catalyst using a rotating disk electrode. The activity was evaluated. For electrochemical measurements, aluminum-polished glassy carbon (geometric region: 0.196 cm ² ) was used.
(Electrode example 1)
The catalyst dispersion was prepared by mixing 5 mg of the catalyst in 6.25 mL of a 25% IPA solution and 12.5 μL of a perfluorocarbon material (Nafion®, 5 wt%). Then, 10 μL of the catalyst dispersion was applied to the surface of glassy carbon and dried. Through the above steps, electrodes in which the catalysts of Example 1 and Comparative Example 1 were supported on glassy carbon were prepared, respectively.
(Electrode example 2)
An electrode on which the catalyst of Comparative Example 3 was supported was produced in the same manner as in Electrode Example 1 except that the amount of the catalyst added to the 25% IPA solution was 2.5 mg.

The electrodes obtained from the catalyst samples of Example 1, Comparative Example 1 and Comparative Example 3 were used as working electrodes, respectively, and the electrodes were pretreated. The pretreatment is performed in a 0.1 M perchloric acid aqueous solution under a nitrogen atmosphere, using a platinum wire as the counter electrode and a reversible hydrogen electrode (RHE) as the reference electrode, in the range of 0.06 to 1.0 V (vs RHE). A CV (Cyclic voltammetry) cycle was performed 50 times at a sweep rate of 50 mV / s and room temperature.

Using the electrode after the pretreatment as the working electrode, the catalytic activity for the oxygen evolution reaction in the acid electrolyte was evaluated. A 0.1 M perchloric acid aqueous solution was used as the electrolytic solution in a nitrogen atmosphere, a platinum wire was used as the counter electrode, and a reversible hydrogen electrode (RHE) was used as the reference electrode. After 25 CV cycles in the range of 1.2 to 1.5 V (vs RHE) at a sweep rate of 50 mV / s and room temperature, LSV (Linear sweep voltammetry) measurement is performed under the following conditions to perform oxygen evolution reaction activity. Was calculated. That is, at an electrode rotation speed of 1600 rpm, potential scanning is performed from 1.2 V to 1.5 V (vs RHE) at a sweep rate of 10 mV / s, and an oxygen evolution reaction per noble metal mass is performed from the current value at a voltage of 1.48 V. The activity was evaluated. FIG. 22 shows the LSV measurement results using the working electrodes of Example 1, Comparative Example 1 and Comparative Example 3 obtained with the electrodes. From FIG. 22, it can be confirmed that the Ru-based nanoparticle-linked catalyst of Example 1 has a significantly higher oxygen evolution reaction activity in an acid environment than that of Comparative Examples 1 and 3.

Moreover, the catalytic activity for the oxygen evolution reaction in the alkaline electrolytic solution was evaluated using the electrode after the pretreatment as the working electrode. As the electrolytic solution, a 0.1 M potassium hydroxide aqueous solution was used under a nitrogen atmosphere, a platinum wire was used as the counter electrode, and a calomel electrode (Hg / HgO) was used as the reference electrode. After 25 CV cycles in the range of 1.2 to 1.5 V (vs RHE) at a sweep rate of 50 mV / s and room temperature, LSV (Linear sweep voltammetry) measurement is performed under the following conditions to perform oxygen evolution reaction activity. Was calculated. That is, at an electrode rotation speed of 1600 rpm, potential scanning is performed from 1.2 V to 1.5 V (vs RHE) at a sweep rate of 10 mV / s, and an oxygen evolution reaction per noble metal mass is performed from the current value at a voltage of 1.48 V. The activity was evaluated. FIG. 23 shows the LSV measurement results using the working electrodes of Example 1, Comparative Example 1 and Comparative Example 3 obtained with the electrodes. From FIG. 23, it was found that the Ru-based nanoparticle-linked catalyst of Example 1 had higher oxygen evolution reaction activity in an alkaline environment than that of Comparative Example 1 and Comparative Example 3.

Table 1 shows the results of the above OER activity evaluation. OER activity was evaluated with a _{current value of 1.48 V i 1.48 V.}

From Table 1, in an alkaline environment, OER mass activity of Example 1 was confirmed to be about 1.5 times that of Comparative Example 1 and about 10 times that of Comparative Example 3. Further, in an acid environment, it was confirmed that Example 1 exhibited OER mass activity 20 times or more as compared with Comparative Example 1 and about 100 times as much as that of Comparative Example 3.

Furthermore, the hydrogen generation reaction activity as a water electrolytic cathode catalyst was evaluated using the electrode after the pretreatment as the working electrode. The electrode after the pretreatment was used as the working electrode, a 0.1 M perchloric acid aqueous solution was used as the electrolytic solution in a nitrogen atmosphere, a platinum wire was used as the counter electrode, and a reversible hydrogen electrode (RHE) was used as the reference electrode. At an electrode rotation speed of 3600 rpm, potential scanning was performed from 0.0 V to −0.5 V (vs RHE) at a sweep speed of 10 mV / s, and LSV (Linear sweep voltammetry) measurement was performed to evaluate the hydrogen generation reaction activity.

The same evaluation was performed in a 0.1 M potassium hydroxide aqueous solution under a nitrogen atmosphere. At that time, a platinum wire was used as the counter electrode, and a calomel electrode (Hg / HgO) was used as the reference electrode. FIGS. 24 and 25 show the LSV measurement results using the working electrodes of Example 1, Comparative Example 1 and Comparative Example 3 obtained with the electrodes. From FIGS. 24 and 25, it can be confirmed that the acid and alkaline electrolytic solutions have the same hydrogen reaction activity as those of Comparative Examples 1 and 3.

[Evaluation of methanol oxidation activity]
The Ru-based nanoparticle coupling catalysts obtained in Examples 1 to 3 and the PtRu / C particles of Comparative Example 1 were evaluated for methanol oxidation reaction activity as a fuel cell anode catalyst using a rotating disk electrode. For electrochemical measurements, aluminum-polished glassy carbon (geometric region: 0.196 cm ² ) was used.

(Electrode example 1)
The catalyst dispersion was prepared by mixing 5 mg of the catalyst in 6.25 mL of a 25% IPA solution and 12.5 μL of a perfluorocarbon material (Nafion®, 5 wt%). Then, 10 μL of the catalyst dispersion was applied to the surface of glassy carbon and dried. Through the above steps, electrodes in which the catalysts of Examples 1 to 3 and Comparative Example 2 were supported on glassy carbon were prepared, respectively.
(Electrode example 2)
An electrode on which the catalyst of Comparative Example 3 was supported was produced in the same manner as in Electrode Example 1 except that the amount of the catalyst added to the 25% IPA solution was 2.5 mg.

The electrodes obtained from the catalyst samples of Examples 1 to 3, Comparative Example 2 and Comparative Example 3 were used as working electrodes, respectively, and the electrodes were pretreated. The pretreatment is performed in a 0.1 M perchloric acid aqueous solution under a nitrogen atmosphere, using a platinum wire as the counter electrode and a reversible hydrogen electrode (RHE) as the reference electrode, in the range of 0.06 to 1.2 V (vs RHE). A CV (Cyclic voltammetry) cycle was performed 50 times at a sweep rate of 50 mV / s and room temperature.

Using the electrode after the pretreatment as the working electrode, the catalytic activity for the methanol oxidation reaction in the alkaline electrolyte was evaluated. As the electrolytic solution, 0.1 M sodium hydroxide + 0.1 M methanol aqueous solution was used under a nitrogen atmosphere, a platinum wire was used as the counter electrode, and a calomel electrode (Hg / HgO) was used as the reference electrode. Five CV cycles were performed in the range of 0.06 to 1.2 V (vs RHE) at a sweep rate of 20 mV / s and room temperature to evaluate carbon monoxide (CO) poisoning resistance in the methanol oxidation reaction. That is, the carbon monoxide (CO) poisoning resistance was evaluated from the ratio of the peak current value If swept in the positive direction and the peak current value Ib when swept in the negative direction, and If / Ib (see FIG. 26). .. As shown in these results, the Ru-based nanoparticle-linked catalyst according to the examples has much better CO poisoning resistance than Comparative Examples 2 and 3, and is excellent in durability.

1: Water electrolyzer, 2: Water electrolyzer, 3: Ru-based nanoparticle connection catalyst,
4: Ion conductor, 5: Solid polymer electrolyte membrane, 6: Cell,
7: External circuit, 8: Membrane electrode assembly,
10: Anode electrode, 11: Anode catalyst layer, 12: Gas diffusion layer, 13: Separator,
14: Gas flow path, 15: Anode unit,
20: Cathode electrode, 21: Cathode catalyst layer, 22: Gas diffusion layer, 23: Separator,
24: Gas flow path, 25: Cathode unit,
30: Capsular catalyst, 31: Reticulated skeleton, 32: Hollow structure, 33: Void,
34: Pre-mold particles, 35: Mold particles, 36: Adhesive catalyst particles,
40: Rod-shaped catalyst, 41: Reticulated skeleton, 43: Voids, 44: Sheet,
50: Aqueous electrolyte solution, 51: Electrolytic cell, 52: Anode electrode, 53: Cathode electrode,
54: partition wall, 55: external circuit,
60: Housing, 61: Gas supply port, 62: Gas discharge port, 63: Housing internal space,
101: Polymer electrolyte fuel cell,
201: Methane hydrogenator.

Claims (16)

A water electrolyzer that electrolyzes water to generate hydrogen and oxygen.
With electrolytes
The anode electrode in contact with the electrolyte and
A cathode electrode for generating hydrogen gas, which is in contact with the electrolyte and is connected to the anode electrode through an external circuit, is provided.
The anode electrode has a network-like skeleton made of a sintered body, in which a plurality of Ru-containing metal nanoparticles are connected to each other to form a large number of voids, on at least a part of the surface of the anode electrode in contact with the electrolyte, and electron conduction is provided. An aqueous electrolyzer using an anode catalyst layer containing a Ru-based nanoparticle linking catalyst exhibiting properties. The Ru-based nanoparticle linking catalyst
A capsule-like catalyst in which the plurality of Ru-containing metal nanoparticles are fused to each other to form a network-like skeleton with a hollow inside.
A rod-shaped catalyst in which the plurality of Ru-containing metal nanoparticles are fused to each other to form a tubular network skeleton, and
The water electrolysis apparatus according to claim 1, wherein the plurality of Ru-containing metal nanoparticles are fused to each other to form at least one of the sheet-like catalysts forming a network-like sheet structure. The water electrolysis apparatus according to claim 1 or 2, wherein the Ru-based nanoparticle linking catalyst is carbon carrier-free. The water electrolysis apparatus according to any one of claims 1 to 3, wherein the Ru-based nanoparticle linking catalyst includes an fcc structure. The water electrolysis apparatus according to any one of claims 1 to 4, wherein the thickness of the anode catalyst layer is 10 μm or less. A membrane electrode assembly in which a polymer electrolyte membrane is arranged between the anode catalyst layer and the cathode catalyst layer.
At least one of the anode catalyst layer and the cathode catalyst layer has a network-like skeleton made of a sintered body, in which a plurality of Ru-containing metal nanoparticles are connected to each other to form a large number of voids, and has electron conductivity. A membrane electrode assembly in which a Ru-based nanoparticle linking catalyst is used. The membrane electrode assembly according to claim 6, wherein the anode catalyst layer has a thickness of 10 μm or less. The membrane electrode assembly according to claim 6 or 7, wherein the Ru-based nanoparticle linking catalyst is carbon carrier-free. The membrane electrode assembly according to any one of claims 6 to 8, wherein the Ru-based nanoparticle linking catalyst includes an fcc structure. The step (a) of forming a mold having a desired shape and having the first polarity, and
The step (b) of adsorbing or in-situ growing Ru-containing metal nanoparticles having a second polarity opposite to the first polarity on the surface of the mold.
After the step (b), a step (c) of obtaining a network-like skeleton in which a plurality of Ru-based nanoparticles connecting catalysts are connected to each other to form a large number of voids by sintering treatment.
The step (d) of incorporating the Ru-based nanoparticle linking catalyst and an ionic conductor having a contact site is provided.
The method for producing a Ru-based nanoparticle-linked catalyst layer, wherein the ionic conductor in step (d) is at least one of the following (i) to (iii).
(I) A component contained in the mold incorporated in the step (a).
(Ii) It is obtained by converting the component contained in the template as a precursor after the step (c).
(Iii) It is introduced by adding a new step after the step (c). The Ru-based nanoparticle linking catalyst is
A capsule-like catalyst in which the plurality of Ru-containing metal nanoparticles are fused to each other to form a network-like skeleton with a hollow inside.
A rod-shaped catalyst in which the plurality of Ru-containing metal nanoparticles are fused to each other to form a tubular network skeleton, and
It is at least one of the sheet-like catalysts in which the plurality of Ru-containing metal nanoparticles are fused to each other to form a network-like sheet structure.
The method for producing a Ru-based nanoparticle-linked catalyst layer according to claim 10, wherein the ion conductor is provided inside or outside the Ru-based nanoparticle-linked catalyst. The method for producing a Ru-based nanoparticle-linked catalyst layer according to claim 10 or 11, wherein the sintering treatment is a supercritical treatment or a subcritical treatment. The method for producing a Ru-based nanoparticle-linked catalyst layer according to any one of claims 10 to 12, wherein the template modifies the surface of the pre-template particles and the surface is composed of template particles having a first polarity. A Ru-based nanoparticle linking catalyst made of a sintered body , having a network-like skeleton in which a plurality of Ru-containing metal nanoparticles are linked to each other to form a large number of voids, and having electron conductivity. A fuel cell having a membrane electrode assembly in which a polymer electrolyte membrane is arranged between an anode catalyst layer and a cathode catalyst layer.
The membrane electrode assembly is the membrane electrode assembly according to any one of claims 6 to 9.
The solid polymer electrolyte membrane is a fuel cell in which at least a part of the Ru-based nanoparticle linking catalyst is in contact with the fuel cell and has an ionic conductor. A catalyst that reforms methane gas into hydrogen gas
Hydrogenation of methane, which is composed of a sintered body and has a network-like skeleton in which a plurality of Ru-containing metal nanoparticles are linked to each other to form a large number of voids, and a Ru-based nanoparticles linking catalyst having electron conductivity is used. Chemical catalyst.

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