Membrane-catalyst layer structure, membrane-electrode assembly, fuel cell, water electrolysis unit, and water electrolysis device

Abstract

A membrane-catalyst layer structure is provided that can maintain good power generation performance or good electrolysis performance for a long time, respectively. A membrane-catalyst layer structure is provided in which a first catalyst layer and a second catalyst layer are sandwiched opposite each other by a membrane comprising at least a polymer electrolyte membrane. The first and second catalyst layers comprise platinum and / or iridium as a first metal, and the first and / or second catalyst layers further comprise at least one element selected from gold, silver, copper, nickel, palladium, cobalt, rhodium, iron, ruthenium, and osmium as a second metal. The membrane comprises a compound N having a nitrogen-containing heterocycle.

Description

TECHNICAL FIELD

[0001] The present application relates to a membrane-catalyst layer structure, a membrane-electrode assembly, a fuel cell, a water electrolysis cell, and a water electrolysis device. BACKGROUND

[0002] A fuel cell is a power generation device that obtains electric energy by electrochemically oxidizing a fuel such as hydrogen or methanol, and is attracting attention as a clean energy supply source. Among them, a solid polymer fuel cell has a low operating temperature and a high energy density, and is expected to be widely used as a power generation device for mobile bodies such as automobiles and ships.

[0003] A solid polymer fuel cell is composed of a plurality of cells, the structure of which is that an anode and a cathode are opposed with a separator containing a polymer electrolyte membrane interposed therebetween, and the solid polymer fuel cell generates electricity by supplying a fuel (hydrogen, methanol) to the anode and an oxidant gas (air, oxygen) to the cathode. In such a solid polymer fuel cell, in order to suppress the crossover of the fuel, an electrolyte membrane containing a nitrogen-containing heterocyclic compound has been proposed (for example, Patent Literature 1).

[0004] In addition, on the other hand, in recent years, hydrogen has attracted attention as a clean energy source instead of fossil fuels, considering environmental problems such as global warming. Hydrogen is expected as a clean energy because it basically releases only water even if it is burned, and does not emit carbon dioxide, which is a cause of global warming. The production of hydrogen is mainly performed by electrolysis of water.

[0005] As a method of producing hydrogen using electrolysis of water, alkaline water electrolysis and polymer electrolyte membrane (PEM) type water electrolysis are known. Among them, the PEM type water electrolysis method can operate at a high current density, and has an advantage that it can flexibly respond to output fluctuations of renewable energy.

[0006] The PEM type water electrolysis method is a method of supplying water to a water electrolysis cell in which an anode and a cathode are opposed with a separator containing a polymer electrolyte membrane interposed therebetween, generating oxygen gas at the anode, and generating hydrogen gas at the cathode.

[0007] As a polymer electrolyte constituting a polymer electrolyte membrane, a fluorine-based polymer electrolyte and a hydrocarbon-based polymer electrolyte are known, and as an anode catalyst, iridium is used, and as a cathode catalyst, platinum is used (for example, see Patent Literatures 2 to 3).

[0008] PRIOR ART DOCUMENTS

[0009] PATENT LITERATURE

[0010] Patent Literature 1: Japanese Patent Application Laid-Open No. 2019-507006

[0011] Patent Document 2: Japanese Patent Application Publication No. 2023-112816

[0012] Patent Document 3: Japanese Patent Application Publication No. 2018-159121 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] In the field of fuel cells, there is a requirement to maintain high power generation performance for a long time, but the technology described in the aforementioned patent documents is not sufficient.

[0015] On the other hand, in the field of water electrolysis, reducing the cost of hydrogen production is required to popularize hydrogen energy. To reduce hydrogen production costs, it is effective to maintain high electrolysis performance for an extended period within the same water electrolysis unit without replacing the unit. However, the technology described in the aforementioned patent documents is insufficient.

[0016] Therefore, in view of the above-mentioned issues, the object of the present invention is to provide a membrane-catalyst layer structure that can maintain good power generation performance or good electrolysis performance for a long time, respectively.

[0017] Methods for solving problems

[0018] The above-mentioned objective of the present invention is achieved through the following invention. That is,

[0019] [1] A membrane-catalyst layer structure, wherein a first catalyst layer and a second catalyst layer are sandwiched between a membrane comprising at least a polymer electrolyte membrane, the first catalyst layer and the second catalyst layer comprising platinum and / or iridium as a first metal, the first catalyst layer and / or the second catalyst layer further comprising at least one element selected from gold, silver, copper, nickel, palladium, cobalt, rhodium, iron, ruthenium and osmium as a second metal, and the membrane comprising a compound N having a nitrogen-containing heterocycle.

[0020] [2] According to the membrane-catalyst layer structure described in [1], the compound N having a nitrogen-containing heterocycle contains a nitrogen-containing aromatic five-membered ring or a nitrogen-containing aromatic six-membered ring.

[0021] [3] According to the membrane-catalyst layer structure described in [1] or [2], the above-mentioned compound N having a nitrogen-containing heterocycle contains a nitrogen-containing aromatic six-membered ring.

[0022] [4] According to any one of [1] to [3], the above-mentioned compound N having nitrogen-containing heterocycles contains a plurality of nitrogen-containing aromatic six-membered rings.

[0023] [5] According to any one of [1] to [4], the compound N having a nitrogen-containing heterocycle is a compound selected from general formulas (D1), (D2) and (D3).

[0024]

[0025] In the formula, R 1 It represents at least one group selected from the group consisting of divalent or higher hydrocarbon groups, amino groups, thioether groups, ketone groups, sulfonyl groups, sulfone groups, and ether groups, where n = 1 Q. 1 Each of the following can be independently represented as a five-membered or six-membered nitrogen-containing aromatic heterocycle, a fused ring formed by these nitrogen-containing aromatic heterocycles, or a fused ring formed by these nitrogen-containing aromatic heterocycles and a hydrocarbon aromatic ring, wherein these nitrogen-containing aromatic heterocycles and hydrocarbon aromatic rings can be substituted with any substituent. n1 represents an integer from 2 to 10.

[0026]

[0027] In the formula, R 2 Q represents at least one group selected from hydrocarbon, amino, thioether, ketone, sulfonyl, sulfone, and ether groups, or directly bonded. 2 This indicates a group consisting of 1 to 5 nitrogen-containing aromatic heterocycles (five- or six-membered rings), fused rings formed by these nitrogen-containing aromatic heterocycles, or fused rings formed by these nitrogen-containing aromatic heterocycles and hydrocarbon aromatic rings, respectively. Both the nitrogen-containing aromatic heterocycles and the hydrocarbon aromatic rings can be substituted with any substituents. n2 represents an integer from 1 to 20. X 1 and X 2 Each of these groups independently represents at least one group selected from hydrogen, halogen, hydrocarbon, alkoxy, aryloxy, carboxyl, carboxylic acid ester, phosphono, phosphonic oxide, phosphonic acid, phosphate ester, sulfonic acid, sulfate ester, hydroxyl, amino, cyano, and nitro.

[0028]

[0029] In the formula, R 3 C(R) represents a nitrogen atom, R represents a hydrogen atom or an alkyl group, and Q represents a nitrogen atom. 3 This indicates a nitrogen-containing aromatic heterocycle with a five- or six-membered ring, a fused ring formed by these nitrogen-containing aromatic heterocycles, or a fused ring formed by these nitrogen-containing aromatic heterocycles and a hydrocarbon aromatic ring, wherein these nitrogen-containing aromatic heterocycles and the hydrocarbon aromatic ring can be substituted with any substituent. g represents an integer from 5 to 500.

[0030] [6] According to any one of [1] to [5], the first catalyst layer is an oxygen evolution catalyst layer containing iridium as the first metal, and the second catalyst layer is a proton reduction catalyst layer containing platinum as the first metal.

[0031] [7] According to any one of [1] to [5], the first catalyst layer is an oxygen reduction catalyst layer containing platinum as the first metal, and the second catalyst layer is a hydroxide catalyst layer containing platinum as the first metal.

[0032] [8] According to the membrane-catalyst layer structure described in [6], the second catalyst layer contains ruthenium as the second metal.

[0033] [9] According to the membrane-catalyst layer structure described in [6] or [8], the second catalyst layer comprises carbon particles supported on platinum, or carbon particles supported on platinum and ruthenium.

[0034]

[10] According to the membrane-catalyst layer structure described in [8] or [9], the second catalyst layer comprises carbon particles supported on a platinum-ruthenium alloy.

[0035]

[11] According to any one of [1], [6], [8] to

[10] , the first catalyst layer contains iridium as the first metal and iridium oxide as the iridium element.

[0036]

[12] The membrane-catalyst layer structure according to any one of [1] to

[11] further comprises a polymer electrolyte in the first catalyst layer and the second catalyst layer.

[0037]

[13] According to any one of [1], [6], [8] to

[12] , the first catalyst layer comprises iridium as a first metal and a polymer electrolyte, wherein the mass ratio (Ya) of the polymer electrolyte to the mass of the iridium is 0.05 or more and less than 0.5, and the second catalyst layer comprises platinum as a first metal, ruthenium as a second metal and a polymer electrolyte, wherein the mass ratio (Yc) of the polymer electrolyte to the total mass of the platinum and ruthenium is 0.25 or more and less than 1.1.

[0038]

[14] According to the membrane-catalyst layer structure described in

[13] , the above ratio (Ya) is less than the above ratio (Yc).

[0039]

[15] In any one of [1] to

[14] , the thickness of the first catalyst layer and / or the second catalyst layer is 25% or less, relative to 100% of the thickness of the diaphragm.

[0040]

[16] The membrane-catalyst layer structure according to any one of [1] to

[15] , wherein the polymeric electrolyte membrane comprises a hydrocarbon-based polymeric electrolyte.

[0041]

[17] According to the membrane-catalyst layer structure described in [1] or [7], the first catalyst layer is an anode catalyst layer and the second catalyst layer is a cathode catalyst layer.

[0042]

[18] A fuel cell comprising the membrane-catalyst layer structure described in any one of [1] to

[17] .

[0043]

[19] A water electrolysis device comprising the membrane-catalyst layer structure described in any one of [1] to

[17] .

[0044]

[20] A membrane-electrode junction is formed by disposing electrode substrates on both sides of a membrane-catalyst layer structure as described in any one of [1] to

[17] .

[0045]

[21] A fuel cell comprising the membrane-electrode junction described in

[20] .

[0046]

[22] A water electrolysis unit comprising the membrane-electrode junction described in

[20] .

[0047]

[23] A water electrolysis apparatus comprising the water electrolysis unit described in

[22] .

[0048] The effects of the invention

[0049] The membrane-catalyst layer structure of the present invention can maintain good electrolysis performance for a long time in fuel cells and in water electrolysis. Attached Figure Description

[0050] Figure 1 A cross-sectional schematic diagram showing an example of the water electrolysis unit of the present invention. Detailed Implementation

[0051] The embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be implemented with various modifications according to the purpose and use.

[0052] The membrane-catalyst layer structure according to embodiments of the present invention comprises a first catalyst layer and a second catalyst layer sandwiching a membrane containing a polymer electrolyte membrane. Furthermore, by including a combination of the membrane containing a compound N having a nitrogen-containing heterocyclic ring (hereinafter sometimes simply referred to as "compound N"), and the first catalyst layer and the second catalyst layer each containing the following metals, good power generation performance or good electrolysis performance can be maintained for a long time, respectively.

[0053] That is, the first catalyst layer and the second catalyst layer contain platinum and / or iridium as the first metal, and the first catalyst layer and / or the second catalyst layer also contain at least one element selected from gold, silver, copper, nickel, palladium, cobalt, rhodium, iron, ruthenium and osmium as the second metal.

[0054] [Septum]

[0055] The separator comprises at least a polymeric electrolyte membrane. The polymeric electrolyte membrane contains a polymeric electrolyte. The separator may consist solely of the polymeric electrolyte membrane, or it may be a laminate of the polymeric electrolyte membrane and other layers. Details regarding the other layers will be described later. In the case where the separator is a laminate of the polymeric electrolyte membrane and other layers, compound N may be included in any one or more of the layers constituting the separator. In this invention, compound N is preferably included at least in the polymeric electrolyte membrane.

[0056] From the viewpoint of maintaining good power generation or electrolysis performance over a long period, the content of compound N in the membrane is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and particularly preferably 0.2 parts by mass or more, relative to 100 parts by mass of the polymeric electrolyte contained in the membrane. Furthermore, the above-mentioned content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, and particularly preferably 1 part by mass or less.

[0057] In fuel cells, from the viewpoint of maintaining good power generation performance over a long period of time, the thickness of the membrane is preferably 2 μm or more, more preferably 3 μm or more, and particularly preferably 4 μm or more. The aforementioned thickness is preferably 30 μm or less, more preferably 20 μm or less, and particularly preferably 15 μm or less.

[0058] On the other hand, in water electrolysis, from the viewpoint of maintaining good electrolysis performance over a long period of time, the thickness of the diaphragm is preferably 20 μm or more, more preferably 30 μm or more, even more preferably 40 μm or more, and particularly preferably 50 μm or more. The aforementioned thickness is preferably 250 μm or less, more preferably 200 μm or less, even more preferably 180 μm or less, and particularly preferably 150 μm or less.

[0059] [Compound N]

[0060] Nitrogen-containing heterocycles constituting compound N are preferably nitrogen-containing aromatic heterocycles or nitrogen-containing aliphatic heterocycles. Among these, nitrogen-containing aromatic heterocycles are preferred.

[0061] Examples of nitrogen-containing aromatic heterocycles include, for example, pyridine rings, pyridazine rings, pyrimidine rings, pyrazine rings, triazine rings, pyrrole rings, pyrazole rings, imidazole rings, triazole rings, and tetraazole rings. azole ring, Diazole rings, thiazole rings, thiadiazole rings, selenazole rings, etc. Nitrogen-containing aromatic heterocycles can also be substances obtained by fusion of the above-mentioned heterocycles, such as imidazopyridine and imidazopyrimidine. Alternatively, they can be benzimidazole, benzo[…] Substances obtained by fusion of nitrogen-containing aromatic heterocycles with hydrocarbon aromatic rings, such as azoles, benzothiazoles, quinoline, quinoxaline, and phenanthrene. Among the aforementioned hydrocarbon aromatic rings, benzene rings, naphthalene rings, anthracene rings, and phenanthrene rings are preferred, with benzene rings being more preferred.

[0062] Among the nitrogen-containing aromatic heterocycles, nitrogen-containing five-membered and six-membered aromatic rings are preferred, with nitrogen-containing six-membered aromatic rings being particularly preferred. More preferably, these nitrogen-containing five-membered or six-membered aromatic rings are fused with hydrocarbon aromatic rings (e.g., benzene rings, naphthalene rings, anthracene rings, phenanthrene rings), and even more preferably, nitrogen-containing six-membered aromatic rings are fused with hydrocarbon aromatic rings. Particularly preferred are two nitrogen-containing six-membered aromatic rings fused with one hydrocarbon aromatic ring. The number of nitrogen-containing six-membered aromatic rings constituting compound N is preferably two or more, more preferably three or more, and particularly preferably four or more.

[0063] The number of nitrogen-containing heterocycles in compound N is preferably 2 or more, more preferably 3 or more, and particularly preferably 4 or more. Furthermore, the aforementioned number is preferably 1,000 or less, more preferably 800 or less, and particularly preferably 500 or less. Compound N can be either a non-polymer (low molecular weight) or a polymer (high molecular weight). When compound N is a non-polymer, the number of nitrogen-containing heterocycles is preferably less than 30, preferably 20 or less, and particularly preferably 15 or less. When compound N is a polymer, the number of nitrogen-containing heterocycles is preferably 30 or more, preferably 40 or more, and particularly preferably 50 or more.

[0064] In water electrolysis, from the viewpoint of maintaining good electrolytic performance for a longer period, it is also suitable to use compound N, which is not easily dissolved from the membrane during water electrolysis operation. From this perspective, the molecular weight of compound N used in water electrolysis is preferably relatively large, specifically, preferably 200 or more, more preferably 300 or more, and particularly preferably 400 or more. Furthermore, during membrane fabrication, it is preferable that compound N is easily mixed with the polymeric electrolyte; from this perspective, the molecular weight of compound N is preferably 200,000 or less, more preferably 150,000 or less, and particularly preferably 100,000 or less. Here, when compound N is a polymer, this molecular weight is the exponential average molecular weight.

[0065] Compound N is preferably a compound represented by the following general formula (D1), (D2) or (D3).

[0066]

[0067] R 1It represents at least one group selected from the group consisting of divalent or higher hydrocarbon groups, amino groups, thioether groups, ketone groups, sulfonyl groups, sulfone groups, and ether groups, where n = 1 Q. 1 Each of the following can be independently represented as a five-membered or six-membered nitrogen-containing aromatic heterocycle, a fused ring formed by these nitrogen-containing aromatic heterocycles, or a fused ring formed by these nitrogen-containing aromatic heterocycles and a hydrocarbon aromatic ring, wherein these nitrogen-containing aromatic heterocycles and hydrocarbon aromatic rings can be substituted with any substituent. n1 represents an integer from 2 to 10.

[0068]

[0069] R 2 Q represents at least one group selected from hydrocarbon, amino, thioether, ketone, sulfonyl, sulfone, and ether groups, or directly bonded. 2 This indicates a group consisting of 1 to 5 nitrogen-containing aromatic heterocycles (five- or six-membered rings), fused rings formed by these nitrogen-containing aromatic heterocycles, or fused rings formed by these nitrogen-containing aromatic heterocycles and hydrocarbon aromatic rings, respectively. Both the nitrogen-containing aromatic heterocycles and the hydrocarbon aromatic rings can be substituted with any substituents. n2 represents an integer from 1 to 20. X 1 and X 2 Each of these groups independently represents at least one group selected from hydrogen, halogen, hydrocarbon, alkoxy, aryloxy, carboxyl, carboxylic acid ester, phosphono, phosphonic oxide, phosphonic acid, phosphate ester, sulfonic acid, sulfate ester, hydroxyl, amino, cyano, and nitro.

[0070]

[0071] R 3 C(R) represents a nitrogen atom, R represents a hydrogen atom or an alkyl group, and Q represents a nitrogen atom. 3 This indicates a nitrogen-containing aromatic heterocycle with a five- or six-membered ring, a fused ring formed by these nitrogen-containing aromatic heterocycles, or a fused ring formed by these nitrogen-containing aromatic heterocycles and a hydrocarbon aromatic ring, wherein these nitrogen-containing aromatic heterocycles and the hydrocarbon aromatic ring can be substituted with any substituent. g represents an integer from 5 to 500.

[0072] In the above general formulas (D1) and (D2), the term "amino" refers to primary to tertiary amino groups and quaternary ammonium cations. Furthermore, the term "i-valent (i=1~3) or higher bonding sites" refers to sites having i or more that can bond with other structural units.

[0073] Additionally, as R 1 R 2 X 1 X 2 The hydrocarbon group represented can be, for example, represented by the general formula C m H n(m and n represent integers, m is preferably 1~20) represents a straight-chain, cyclic, or branched hydrocarbon group. The hydrocarbon group can be aliphatic or aromatic, but aromatic is preferred. The hydrocarbon group can be substituted with any substituent.

[0074] The term "any substituent" in the description of all the above groups is not particularly limited, but halogen, alkyl, alkoxy, aryl, aryloxy, carboxyl, carboxylic acid ester, phosphonyl, phosphonic oxide, phosphonic acid, phosphate ester, sulfonic acid, sulfate ester, hydroxyl, amino, cyano, and nitro are preferred.

[0075] The following examples illustrate compounds represented by the above general formula (D1), but are not limited to these.

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084] Among the compounds represented by the above general formula (D1), compounds having a nitrogen-containing aromatic six-membered ring are preferred, and compounds represented by the following general formula (D1a) are more preferred.

[0085]

[0086] In general formula (D1a), Ar 1 R represents the k-valence of a aryl group. 4 Each group independently represents at least one group selected from the group consisting of a halogen group, an alkyl group with 1 to 20 carbon atoms, an alkoxy group with 1 to 20 carbon atoms, an aryl group with 6 to 20 carbon atoms, an aryloxy group with 6 to 20 carbon atoms, a carboxyl group, a carboxylic acid ester group, a phosphonyl group, a phosphonic acid ester group, a phosphate ester group, a sulfonic acid ester group, a sulfate ester group, a hydroxyl group, an amino group, a cyano group, and a nitro group. j represents an integer greater than or equal to 0 and less than or equal to 7, and k represents an integer greater than or equal to 2.

[0087] Next, examples of compounds represented by the above general formula (D2) will be given, but are not limited to these.

[0088]

[0089]

[0090]

[0091]

[0092] Among the compounds represented by the above general formula (D2), compounds having a nitrogen-containing aromatic six-membered ring are preferred, and compounds represented by the following general formula (D2a) are more preferred.

[0093]

[0094] In general formula (D2a), Ar 2 R represents a aryl group. 5 Each of the following groups independently represents at least one group selected from the group consisting of a halogen group, an alkyl group with 1 to 20 carbon atoms, an alkoxy group with 1 to 20 carbon atoms, an aryl group with 6 to 20 carbon atoms, an aryloxy group with 6 to 20 carbon atoms, a carboxyl group, a carboxyl ester group, a phosphonyl group, a phosphonic acid group, a phosphate ester group, a sulfonic acid group, a sulfate ester group, a hydroxyl group, an amino group, a cyano group, and a nitro group. 3 and X 4 Each group independently represents at least one group selected from the following: hydrogen atom, halogen group, alkyl group with 1 to 20 carbon atoms, alkoxy group with 1 to 20 carbon atoms, aryl group with 6 to 20 carbon atoms, aryloxy group with 6 to 20 carbon atoms, carboxyl group, carboxylic acid ester group, phosphonyl group, phosphonic oxide group, phosphonic acid group, phosphate ester group, sulfonic acid group, sulfate ester group, hydroxyl group, amino group, cyano group, and nitro group. m represents an integer greater than or equal to 0 and less than or equal to 6, and n3 represents an integer greater than or equal to 2 and less than or equal to 4.

[0095] Next, examples of compounds represented by the above general formula (D3) will be given, but are not limited to these.

[0096]

[0097] Compound N can also be a compound that is not equivalent to any of the general formulas (D1), (D2), and (D3), as long as it is a compound having a nitrogen-containing heterocycle. Examples of such compounds are given below, but this is not a limitation.

[0098] (H1)1,10-Phenanthroline

[0099] (H2)5-Amino-1,10-Phenanthroline

[0100] (H3) Polybenzimidazole (PBI).

[0101] The above-mentioned polybenzimidazole (PBI) includes all compounds whose main chain has a benzimidazole structure. As PBI, the following formula (H3) is suitable.

[0102]

[0103] Furthermore, regarding compound N, a macrocyclic compound may be suitable as a compound that is not equivalent to any of the general formulas (D1), (D2), and (D3). Examples of macrocyclic compounds include compounds having a porphyrin skeleton, a porphyrin skeleton, a phthalocyanine skeleton, and a azidocalixarene skeleton. Specifically, examples include porphyrin, porphyrin, protoporphyrin, phthalocyanine, carbophen, dihydroporphyrin, chlorophyll, coprophyrinogen I, coprophyrinogen III, uroporphyrinogen I, uroporphyrinogen III, protoporphyrinogen IX, and azidocalixarene, but there are no particular limitations. Among these, porphyrin, porphyrin, phthalocyanine, and azidocalixarene are preferred, and porphyrin and phthalocyanine are more preferred.

[0104] [Polymer electrolyte membrane]

[0105] As described above, the polymeric electrolyte membrane contains a polymeric electrolyte. In this invention, a polymeric electrolyte membrane refers to a membrane containing 50% by mass or more polymeric electrolyte per 100% by mass of the total solid components. The content of the polymeric electrolyte is further preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[0106] Examples of the polymeric electrolytes used in this invention include fluorinated polymeric electrolytes and hydrocarbon-based polymeric electrolytes. In this invention, the polymeric electrolyte membrane preferably comprises a hydrocarbon-based polymeric electrolyte.

[0107] Fluorinated polymers with ionic groups are preferred as fluorinated polymeric electrolytes. Fluorinated polymers are polymers in which most or all of the hydrogen atoms in the alkyl and / or alkylene groups of the molecule are replaced by fluorine atoms.

[0108] Preferred examples of fluorine-based polymeric electrolytes include, for instance, perfluorinated carbon sulfonic acid polymers, perfluorinated carbon phosphonic acid polymers, trifluorostyrene sulfonic acid polymers, trifluorostyrene phosphonic acid polymers, ethylene tetrafluoroethylene-g-styrene sulfonic acid polymers, ethylene-tetrafluoroethylene copolymers, and polyvinylidene fluoride-perfluorinated carbon sulfonic acid polymers.

[0109] Among them, considering heat resistance and chemical stability, perfluorinated carbon sulfonic acid polymers are preferred. Examples of such polymers include, (Registered Trademark) (Company system) (Registered trademark) (AGC Corporation) and " "(Registered trademark) (Asahi Kasei Corporation) and other commercially available products."

[0110] As a hydrocarbon-based polymeric electrolyte, a hydrocarbon polymer having an ionic group is preferred. A hydrocarbon polymer is defined as a polymer having a main chain with hydrocarbons as the main structural unit. Among the aforementioned hydrocarbon polymers, aromatic hydrocarbon polymers with aromatic rings in the main chain are preferred. That is, aromatic hydrocarbon polymers are preferred among hydrocarbon-based polymeric electrolytes.

[0111] As an aromatic hydrocarbon polymer, preferred examples include those whose main chain comprises polysulfone, polyethersulfone, polyphenylene ether, polyarylene ether, polyphenylene sulfide, polyphenylene sulfide sulfone, poly(p-phenylene), polyarylene polymers, polyarylene ketones, polyether ketones, polyarylene phosphine oxides, polyether phosphine oxides, and polyphenylene oxides. Polymers of structures and aromatic rings in azoles, polybenzothiazoles, polybenzimidazoles, polyamides, polyimides, polyetherimides, and polyimide sulfones.

[0112] It should be noted that the term "polysulfone" refers to a general term for structures with sulfone bonds in their molecular chains; "polyethersulfone" refers to a general term for structures with both ether and sulfone bonds in their molecular chains; and "polyetherketone" refers to a general term for structures with both ether and ketone bonds in their molecular chains. Aromatic hydrocarbon polymers can possess multiple of these structures.

[0113] As aromatic hydrocarbon polymers, polyetherketone polymers are particularly preferred. Examples of polyetherketone polymers include, for example, polyetherketone, polyetherketoneketone, polyetheretherketone, polyetheretherketone, and polyetherketoneetherketone.

[0114] Furthermore, among aromatic hydrocarbon polymers, block copolymers are preferred. Here, a block copolymer refers to a block copolymer containing segments of structural units containing ionic groups and segments of structural units containing non-ionic groups.

[0115] The aforementioned ionic groups can be any ionic group possessing either cation exchange capability or anion exchange capability, but in this invention, proton exchangeable ionic groups are preferred. Examples of such functional groups include sulfonic acid groups, sulfonylimide groups, sulfate groups, phosphonic acid groups, phosphate groups, carboxylic acid groups, and ammonium groups. The polymer may contain two or more ionic groups, including amino groups and sulfonic acid groups. From the perspective of excellent water electrolysis performance, sulfonic acid groups, sulfonylimide groups, and sulfate groups are preferred; from the perspective of raw material cost, sulfonic acid groups are more preferred.

[0116] As described above, aromatic hydrocarbon block copolymers are preferred as polymeric electrolytes, and polyetherketone block copolymers are more preferred. Among polyetherketone block copolymers, substances containing segments comprising structural units (S1) containing ionic groups as described below, and segments comprising structural units (S2) not containing ionic groups, are particularly preferred.

[0117]

[0118] In general formula (S1), Ar 11 ~Ar 14 Ar represents any divalent aryl group. 11 and / or Ar 12 Contains ionic groups, Ar 13 and Ar 14 It may or may not contain ionic groups. Ar 11 ~Ar 14 It can be arbitrarily replaced, and more than two aryl groups can be used independently. * indicates the bonding site with the general formula (S1) or other structural units.

[0119]

[0120] In general formula (S2), Ar 15 ~Ar 18 Ar represents any divalent aryl group, which can be arbitrarily substituted, but does not contain ionic groups. 15 ~Ar 18 Two or more aryl groups can be used independently. * indicates the bonding site with the general formula (S2) or other structural units.

[0121] Here, as Ar 11 ~Ar 18 Preferred divalent arylene groups include, but are not limited to, hydrocarbon-based arylene groups such as phenylene, naphthylene, biphenylene, and fluorene, as well as heteroarylene groups such as pyridylene, quinoxalinylene, and thiopheneylene. Here, "phenylene" is used in three ways depending on the position of the bonding site between the benzene ring and other structural units: ortho-phenylene, meta-phenylene, and para-phenylene. However, unless otherwise specified in this specification, it is used as a general term for these groups. The same applies to "naphthylene," "biphenylene," and other divalent arylene groups. 11 ~Ar 14 Preferably, it is a phenylene compound containing a phenylene group and an ionic group; most preferably, it is a p-phenylene compound containing a p-phenylene group and an ionic group. Additionally, Ar... 15 ~Ar 18 It can be replaced by groups other than ionic groups, but considering proton conductivity, chemical stability and physical durability, it is better to have no substitution.

[0122] The ion exchange capacity (IEC) of the polymeric electrolyte is preferably 0.5 meq / g or more and 3.5 meq / g or less. Considering both good electrolysis performance and good power generation performance, in the case of hydrocarbon-based polymeric electrolytes, the IEC is more preferably 1.0 meq / g or more and 3.5 meq / g or less, further preferably 1.4 meq / g or more and 3.0 meq / g or less, and particularly preferably 1.6 meq / g or more and 2.7 meq / g or less. In the case of fluorinated polymeric electrolytes, the IEC is more preferably 0.5 meq / g or more and 2.0 meq / g or less, further preferably 0.7 meq / g or more and 1.7 meq / g or less, and particularly preferably 0.8 meq / g or more and 1.5 meq / g or less.

[0123] Here, IEC refers to the molar amount of ionic groups introduced per unit dry weight of the polymeric electrolyte P. A higher value indicates a greater amount of ionic groups introduced. In this invention, IEC is defined as the value obtained through neutralization titration.

[0124] For the polymeric electrolyte constituting the polymeric electrolyte membrane, considering better electrolytic performance and power generation performance, a polymeric electrolyte with an IEC of 1.6 meq / g or higher is preferred, more preferably 1.7 meq / g or higher, and particularly preferably 1.8 meq / g or higher. Considering durability, the IEC of the polymeric electrolyte is preferably 3.0 meq / g or lower, more preferably 2.7 meq / g or lower, and particularly preferably 2.5 meq / g or lower.

[0125] Among the aforementioned polymeric electrolytes, hydrocarbon-based polymeric electrolytes are preferred due to their superior electrolytic and power generation performance. Among hydrocarbon-based polymeric electrolytes, aromatic hydrocarbon-based polymeric electrolytes are preferred, and polyetherketone block copolymers are even more particularly preferred.

[0126] The content of hydrocarbon-based polymeric electrolyte is preferably 60% or more by mass, more preferably 75% or more by mass, further preferably 90% or more by mass, and particularly preferably 100% by mass, relative to the total mass of polymeric electrolytes contained in the polymeric electrolyte membrane of 100% by mass.

[0127] Polymer electrolyte membranes can be composed of multiple layers. When a polymer electrolyte membrane is composed of multiple layers, the structures of the polymer electrolytes contained in each layer can be the same or different. Examples of such multiple layers include, for example, a stacked structure containing a layer containing a hydrocarbon-based polymer electrolyte and a layer containing a fluorine-based polymer electrolyte; or a non-composite layer containing a polymer electrolyte but not a porous substrate on one or both sides of a composite layer containing a porous substrate and a polymer electrolyte. The aforementioned composite layer is a layer in which the polymer electrolyte is filled into the pores of the porous substrate. Examples of porous substrates include fabrics, nonwoven fabrics, porous membranes, and mesh fabrics.

[0128] When the thickness of the polymer electrolyte membrane is set to 100%, the thickness ratio of the composite layer is preferably 10-90%, more preferably 20-80%, and particularly preferably 30-70%. Here, the thickness of the composite layer refers to the thickness of the porous substrate. In the electrolyte membrane used for water electrolysis, the specific thickness of the composite layer is preferably in the range of 22-47 μm, more preferably in the range of 25-45 μm, and particularly preferably in the range of 30-43 μm. Furthermore, the thickness of each non-composite layer is preferably 3 μm or more, more preferably 5 μm or more, and particularly preferably 10 μm or more. Additionally, the thickness of each non-composite layer is preferably 45 μm or less, more preferably 40 μm or less, and particularly preferably 35 μm or less.

[0129] When the polymeric electrolyte membrane is composed of multiple layers, examples include a configuration where all layers contain compound N and a configuration where some layers contain compound N. In the latter case, it is preferable that compound N is contained at least in the layer closest to the cathode catalyst layer.

[0130] Without impairing the effects of the present invention, the polymer electrolyte membrane may contain various additives, such as antioxidants, surfactants, free radical scavengers, hydrogen peroxide decomposers, non-electrolyte polymers, elastomers, fillers, etc.

[0131] From the viewpoint of maintaining good electrolytic performance over a long period of time in water electrolysis, the thickness of the polymer electrolyte membrane is preferably 20 μm or more, more preferably 30 μm or more, even more preferably 40 μm or more, and particularly preferably 50 μm or more. The aforementioned thickness is preferably 250 μm or less, more preferably 200 μm or less, even more preferably 180 μm or less, and particularly preferably 150 μm or less.

[0132] [Other layers]

[0133] The membrane may include layers other than the polymer electrolyte membrane. Here, "other layers" refers to layers whose polymer electrolyte content is less than 50% by mass relative to the total solid content of other layers. There are no particular limitations on what constitutes an "other layer," and various functional layers can be cited. Examples include protective layers (protecting the polymer electrolyte membrane), adhesive layers (strengthening the adhesion between the polymer electrolyte membrane and the catalyst layer), and gas migration suppression layers (decomposing and capturing gases such as hydrogen, oxygen, and hydrogen peroxide). Additionally, other layers can also be layers used to introduce compound N into the membrane. These other layers may contain the polymer electrolyte as long as it does not impair their function.

[0134] When other layers are provided, their thickness is preferably in the range of 0.1 to 30 μm, more preferably in the range of 0.5 to 20 μm, and particularly preferably in the range of 1 to 15 μm.

[0135] [Catalyst layer]

[0136] The membrane-catalyst layer structure according to embodiments of the present invention has a first catalyst layer disposed on one side of a membrane and a second catalyst layer disposed on the other side of the membrane. Furthermore, the first and second catalyst layers contain platinum and / or iridium as the first metal, and the first and / or second catalyst layers further contain at least one element selected from gold, silver, copper, nickel, palladium, cobalt, rhodium, iron, ruthenium, and osmium as the second metal.

[0137] In a fuel cell, the first catalyst layer preferably functions as an oxygen reduction catalyst layer, and the second catalyst layer preferably functions as a hydrogenation catalyst layer. Furthermore, the first catalyst layer (oxygen reduction catalyst layer) preferably contains platinum as a first metal, and the second catalyst layer (hydrogenation catalyst layer) preferably contains platinum as a first metal. Further, the first catalyst layer and / or the second catalyst layer preferably contains at least one element selected from cobalt, nickel, and ruthenium as a second metal.

[0138] In water electrolysis, the first catalyst layer preferably functions as an oxygen evolution catalyst layer, and the second catalyst layer preferably functions as a proton reduction catalyst layer. Furthermore, the first catalyst layer (oxygen evolution catalyst layer) preferably contains iridium as the first metal, and the second catalyst layer (proton reduction catalyst layer) preferably contains platinum as the first metal. More preferably, the second catalyst layer contains ruthenium as the second metal.

[0139] The catalyst layers used in water electrolysis are described in detail below. In water electrolysis, the first catalyst layer (oxygen evolution catalyst layer) is equivalent to the anode catalyst layer, and the second catalyst layer (proton reduction catalyst layer) is equivalent to the cathode catalyst layer. Hereinafter, the first catalyst layer will sometimes be referred to as the "anode catalyst layer," and the second catalyst layer as the "cathode catalyst layer."

[0140] [Anode catalyst layer (first catalyst layer)]

[0141] In water electrolysis, the anode electrolyzes water to produce oxygen and protons; therefore, the anode catalyst is sometimes called an oxygen evolution catalyst. The anode catalyst layer preferably contains iridium as the first metal. Iridium is useful as an oxygen evolution catalyst. That is, by containing iridium as a catalyst, the electrolysis performance of the anode catalyst layer is improved.

[0142] As a catalyst containing iridium, iridium with zero valence, iridium oxide, iridium carbide, iridium nitride, etc., can be used. Considering the ability to maintain good electrolysis performance for a longer period of time, iridium oxide is preferred. The catalyst containing iridium is preferably in particle form.

[0143] Catalysts containing iridium can also be catalyst particles supported on a support formed of metal oxides such as titanium oxide, tin oxide, tantalum oxide, niobium oxide, zirconium oxide, and tungsten oxide. Since the anode in water electrolysis is located in a high-potential environment, a support with high electrochemical oxidation resistance is preferred. In this respect, the aforementioned metal oxides exhibit high electrochemical oxidation resistance and are therefore preferred.

[0144] As a catalyst containing iridium, it is preferable to use iridium-containing particles alone or to use catalyst-supported particles loaded on a support formed of metal oxide. Among these, it is particularly preferable to use iridium-containing particles alone.

[0145] On the other hand, carbon particles such as carbon black are generally known as supports for catalyst-loaded particles. However, in water electrolysis, considering the durability of the anode catalyst layer, it is preferable to have a low carbon particle content. Here, carbon particles include spherical, plate-like, and fibrous materials. The carbon particle content in the anode catalyst layer is preferably less than 0.1 mg / cm³. 2 More preferably less than 0.05 mg / cm³ 2 Further preferred concentration is less than 0.02 mg / cm³. 2 It is specially selected to be completely free of these components.

[0146] Relative to the total elemental mass of all metal catalysts contained in the anode catalyst layer (100% by mass), the iridium content in the anode catalyst layer is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, and particularly preferably 80% by mass or more. The upper limit is preferably 100% by mass or less.

[0147] The anode catalyst layer can contain both iridium and platinum as the first metal. In water electrolysis, the back diffusion of hydrogen generated at the cathode can cause it to mix with oxygen generated at the anode, potentially leading to an explosion. Platinum, acting as a catalyst for the formation of water from hydrogen and oxygen, prevents this explosion. The second metal can also be a substance that acts as a catalyst for the formation of water from hydrogen and oxygen. Examples include noble metals such as ruthenium, rhodium, palladium, gold, silver, and osmium. Among these, palladium is more preferred. Catalysts containing platinum and the aforementioned noble metals can include substances with an oxidation state of 0, oxides, carbides, and nitrides. Substances with an oxidation state of 0 are preferred.

[0148] When the anode catalyst layer contains iridium as well as platinum and / or the aforementioned precious metal elements, the content of platinum and / or the aforementioned precious metal elements is preferably in the range of 1 to 90 parts by mass relative to 100 parts by mass of iridium, more preferably in the range of 5 to 80 parts by mass, and particularly preferably in the range of 10 to 50 parts by mass.

[0149] In the anode catalyst layer, the mass of iridium per unit area is preferably 0.2~2.0 mg / cm³. 2 The range is more preferably 0.4~1.5 mg / cm³. 2 The range is particularly preferred to be 0.6~1.3 mg / cm³. 2 The range.

[0150] The anode catalyst layer preferably also contains a polymeric electrolyte. As the polymeric electrolyte, the aforementioned hydrocarbon-based polymeric electrolytes and fluorinated polymeric electrolytes can be used. Since the anode is located in a high-potential environment in the water electrolysis device, a fluorinated polymeric electrolyte with good resistance to electrochemical oxidation is preferred, and a perfluorinated carbon sulfonate polymer is even more preferred.

[0151] When the anode catalyst layer contains a polymeric electrolyte, from the perspective of electrolysis performance, the ratio (Ya) of the mass of the polymeric electrolyte to the mass of iridium in the anode catalyst layer, i.e., (mass of polymeric electrolyte) / (mass of iridium), is preferably 0.05 or more, more preferably 0.07 or more, and particularly preferably 0.1 or more. Furthermore, from the perspective of the diffusivity of the oxygen gas generated at the anode, the above ratio is preferably less than 0.5, more preferably less than 0.4, further preferably less than 0.3, and particularly preferably less than 0.25.

[0152] From the perspective of electrolysis performance, the thickness of the anode catalyst layer is preferably 0.5 μm or more, more preferably 1 μm or more, and particularly preferably 3 μm or more. Furthermore, considering the diffuseability and physical stability (such as cracking during operation) of the oxygen gas generated at the anode, the aforementioned thickness is preferably 25 μm or less, more preferably 20 μm or less, further preferably 15 μm or less, and particularly preferably 10 μm or less.

[0153] [Cathode catalyst layer (second catalyst layer)]

[0154] In water electrolysis, the cathode catalyst is sometimes referred to as a proton reduction catalyst because it reduces the protons generated at the anode to produce hydrogen gas. The cathode catalyst layer preferably contains platinum as the first metal. Platinum is useful as a proton reduction catalyst.

[0155] The cathode catalyst layer preferably further comprises ruthenium as a second metal. By containing platinum and ruthenium as catalysts, the cathode catalyst layer can maintain good electrolysis performance for a longer period of time. From the viewpoint of maintaining good water electrolysis performance for a longer period of time, the mass ratio of platinum (Pt) to ruthenium (Ru) (Ru / Pt) is preferably 0.1 or more, more preferably 0.2 or more, further preferably 0.3 or more, and particularly preferably 0.4 or more. In addition, the above mass ratio is preferably 2.0 or less, more preferably 1.7 or less, further preferably 1.5 or less, and particularly preferably 1.3 or less. On the other hand, from the viewpoint of water electrolysis performance, the mass ratio of Pt relative to the total mass of Pt and Ru, "Pt / (Pt+Ru)", is preferably 0.40 or more, more preferably 0.50 or more, and particularly preferably 0.60 or more. The above mass ratio "Pt / (Pt+Ru)" is preferably 0.90 or less, more preferably 0.80 or less, and particularly preferably 0.75 or less.

[0156] In the cathode catalyst layer, catalysts containing platinum and catalysts containing ruthenium can be used individually, or platinum-ruthenium alloys can be used, or substances in which platinum and ruthenium are respectively supported on carbon particles. Hereinafter, substances in which platinum is supported on carbon particles are referred to as "platinum-supported carbon particles," substances in which ruthenium is supported on carbon particles are referred to as "ruthenium-supported carbon particles," substances in which platinum and ruthenium are supported on carbon particles are referred to as "platinum and ruthenium-supported carbon particles," and substances in which platinum-ruthenium alloys are supported on carbon particles are referred to as "platinum-ruthenium alloy-supported carbon particles." Furthermore, they are collectively referred to as "carbon particles supported on catalysts such as platinum."

[0157] Examples of carbon particles mentioned above include carbon black such as furnace black, acetylene black, and Ketjen black, as well as substances obtained by graphitizing these carbon blacks.

[0158] When using carbon particles supported on catalysts such as platinum, from the viewpoint of the physical strength and durability of the cathode catalyst layer, the BET specific surface area of ​​the carbon particles supported on catalysts such as platinum is preferably 400 m². 2 / g or less, more preferably 300m 2 / g or less, more preferably 200m 2 / g or less, especially preferably 150m 2 / g or less. The preferred BET specific surface area is 30m². 2 / g or more, preferably 50m 2 / g or more, especially preferred is 70m 2 / g or more.

[0159] From the viewpoint of achieving better electrolysis performance, the catalyst used in the cathode catalyst layer is preferably carbon particles supported on catalysts such as platinum, and more preferably carbon particles supported on platinum and ruthenium. From the viewpoint of maintaining good electrolysis performance for a longer period of time, the catalyst used in the cathode catalyst layer is preferably carbon particles supported on a platinum-ruthenium alloy.

[0160] The loading rate of catalyst elements in carbon particles supported with catalysts such as platinum (the ratio of the mass of the catalyst element to the mass of the carbon particles supported with catalysts such as platinum) is preferably in the range of 20 to 70% by mass, more preferably in the range of 30 to 65% by mass, and particularly preferably in the range of 35 to 60% by mass.

[0161] In the cathode catalyst layer, considering electrolysis performance, the preferred mass of platinum per unit area is 0.05 mg / cm³. 2 The above, more preferably 0.1 mg / cm³ 2 The above, especially preferred, is 0.2 mg / cm³. 2 That's all. Furthermore, from a cost perspective, the mass of the aforementioned platinum element is preferably less than 1.0 mg / cm³. 2 More preferably less than 0.7 mg / cm³ 2 Especially preferred is less than 0.5 mg / cm³. 2 .

[0162] On the other hand, from the perspective of maintaining good electrolytic performance over a long period of time, the preferred mass of ruthenium per unit area is 0.03 mg / cm². 2 The above, more preferably 0.05 mg / cm³ 2 The above, especially preferred, is 0.1 mg / cm³. 2 That's all. Furthermore, the above content is preferably less than 0.8 mg / cm³. 2 More preferably less than 0.6 mg / cm³ 2 Especially preferred is less than 0.4 mg / cm³. 2 .

[0163] The cathode catalyst layer preferably also contains a polymeric electrolyte. As the polymeric electrolyte, the aforementioned hydrocarbon-based polymeric electrolyte or fluorinated polymeric electrolyte can be used. Among these, a fluorinated polymeric electrolyte is preferred, and a perfluorinated carbon sulfonate polymer is even more preferred. Furthermore, it is more preferable that both the anode catalyst layer and the cathode catalyst layer contain a polymeric electrolyte.

[0164] When the cathode catalyst layer contains a polymeric electrolyte, the ion exchange capacity (IEC) of the polymeric electrolyte is preferably less than 1.50 meq / g, more preferably less than 1.40 meq / g, and particularly preferably less than 1.30 meq / g. The lower limit is preferably 0.40 meq / g or more.

[0165] From the perspective of electrolysis performance, the ion exchange capacity (hereinafter referred to as "IEC") of the polymer electrolyte contained in the cathode catalyst layer is... CA The ion exchange capacity (IEC) of the polymer electrolyte membrane is preferably smaller than that of the polymer electrolyte contained in the membrane. PE Specifically, IEC CA With IEC PE The ratio (IEC) CA / IEC PE Preferably, the value is 0.90 or less, more preferably 0.80 or less, even more preferably 0.70 or less, and particularly preferably 0.65 or less. Additionally, the ratio (IEC...) CA / IEC PE Preferably, the value is 0.20 or higher, more preferably 0.30 or higher, even more preferably 0.35 or higher, and particularly preferably 0.40 or higher.

[0166] When the cathode catalyst layer contains a polymeric electrolyte, from the perspective of electrolysis performance, the ratio (Yc) of the mass of the polymeric electrolyte in the cathode catalyst layer to the total mass of platinum and ruthenium, i.e., (mass of polymeric electrolyte) / (mass of platinum + mass of ruthenium), is preferably 0.25 or more, more preferably 0.40 or more, further preferably 0.50 or more, and particularly preferably 0.60 or more. Furthermore, from the perspective of the diffusivity of hydrogen gas generated at the cathode, the above ratio is preferably 1.1 or less, more preferably 1.0 or less, and particularly preferably 0.9 or less.

[0167] Among them, the particularly preferred ratio (Ya) is 0.05 or higher and less than 0.5, and the ratio (Yc) is 0.425 or higher and less than 1.1. The further preferred ratio (Ya) is smaller than the ratio (Yc).

[0168] From the perspective of electrolysis performance, the thickness of the cathode catalyst layer is preferably 0.5 μm or more, more preferably 1 μm or more, and particularly preferably 3 μm or more. Furthermore, considering the diffusion of hydrogen gas generated at the cathode and the physical stability of the catalyst layer (such as cracking during operation), the aforementioned thickness is preferably 25 μm or less, more preferably 20 μm or less, further preferably 15 μm or less, and particularly preferably 10 μm or less.

[0169] [Membrane-catalyst layer structure]

[0170] The membrane-catalyst layer structure according to the embodiments of the present invention has an anode catalyst layer (first catalyst layer) disposed on one side of the membrane and a cathode catalyst layer (second catalyst layer) disposed on the other side.

[0171] The membrane-catalyst layer structure according to embodiments of the present invention can be obtained, for example, by stacking an anode catalyst layer and a cathode catalyst layer onto a membrane, respectively. Alternatively, the membrane-catalyst layer structure of the present invention can be completed in the assembly process of the membrane-electrode assembly described later. Details regarding the latter method will be described later.

[0172] From the viewpoint of ensuring a tight seal between the membrane and the catalyst layer, it is preferable that both the anode catalyst layer and the cathode catalyst layer are stacked on the membrane. Hereinafter, the anode catalyst layer and the cathode catalyst layer will sometimes be collectively referred to as the "catalyst layer".

[0173] Examples of methods for applying catalyst layers to a membrane include coating, transfer, or a combination of both. These methods are not particularly limited, and well-known methods can be employed.

[0174] As a coating method, a known coating method is used to coat the diaphragm with a catalyst layer coating liquid. As a transfer method, an example is to stack a catalyst layer transfer sheet with a catalyst layer laminated on a transfer substrate with a diaphragm and then heat and pressurize it.

[0175] In the membrane-catalyst layer structure according to embodiments of the present invention, the thicknesses of the separator, the anode catalyst layer, and the cathode catalyst layer are as described above. However, from the viewpoint of maintaining good electrolysis performance for a longer period of time, it is preferable to adjust the relationship between these thicknesses. For example, it is preferable that the thickness of the anode catalyst layer and / or the cathode catalyst layer is 25% or less of 100% of the thickness of the separator. The thickness of the anode catalyst layer relative to 100% of the thickness of the separator is preferably 25% or less, more preferably 20% or less, and particularly preferably 15% or less. Furthermore, as a lower limit, it is preferably 1% or more. The thickness of the cathode catalyst layer relative to 100% of the thickness of the separator is preferably 25% or less, more preferably 20% or less, and particularly preferably 15% or less. Furthermore, as a lower limit, it is preferably 1% or more.

[0176] Furthermore, considering the same viewpoints as above, the thickness of the anode catalyst layer relative to 100% of the thickness of the polymer electrolyte membrane is preferably 25% or less, more preferably 20% or less, and particularly preferably 15% or less. As a lower limit, it is preferably 1% or more. The thickness of the cathode catalyst layer relative to 100% of the thickness of the polymer electrolyte membrane is preferably 25% or less, more preferably 20% or less, and particularly preferably 15% or less. As a lower limit, it is preferably 1% or more.

[0177] [Membrane-electrode assembly (MEA)]

[0178] By distributing electrode substrates on both sides of the membrane-catalyst layer structure according to embodiments of the present invention, a membrane-electrode junction is formed. That is, the membrane-electrode junction has an anode catalyst layer and an anode electrode substrate on one side of the membrane, and a cathode catalyst layer and a cathode electrode substrate on the other side.

[0179] For the primary purpose of applying voltage, the electrode substrate (sometimes also serving as a gas diffusion layer) is made of a conductive material. Porous substrates such as metals and carbon can be used as electrode substrates. Examples of metal porous substrates include metal nonwoven fabrics, sintered metal fibers, sintered metal powders, and sintered foamed metals. Examples of carbon porous substrates include carbon felt, carbon paper, carbon cloth, and sintered graphite particles.

[0180] As the anode electrode substrate, a porous metallic substrate with excellent corrosion resistance in environments such as high potential, the presence of oxygen, and strong acidity is preferred. From the above perspective, the metal constituting the porous metallic substrate is preferably titanium, aluminum, nickel, stainless steel, or alloys with at least one of these metals as the main component; titanium and alloys with titanium as the main component are particularly preferred.

[0181] From the perspective of material cost and conductivity, carbon porous substrates are preferred as cathode electrode substrates, and carbon paper is particularly preferred.

[0182] One or both of the anode catalyst layer and the cathode catalyst layer in the membrane-catalyst layer structure according to embodiments of the present invention can be laminated onto an electrode substrate. In the assembly process of the membrane-electrode assembly, an electrode substrate with the catalyst layers laminated and a separator are disposed, thereby forming a configuration in which the anode catalyst layer and the cathode catalyst layer are positioned opposite each other, with the separator sandwiched between them. That is, the membrane-catalyst layer structure is completed in the assembly process of the membrane-electrode assembly, and the present invention includes this method.

[0183] In the above-described manner, the anode catalyst layer and the cathode catalyst layer can be stacked separately on the electrode substrate. However, depending on the type of electrode substrate, sufficient adhesion between the catalyst layer and the substrate may not be achieved. Therefore, it is preferable to select an appropriate substrate based on its type. For example, porous carbon substrates exhibit good adhesion to the catalyst layer. Therefore, the cathode catalyst layer can be stacked on a suitable porous carbon substrate as the cathode electrode substrate, and the anode catalyst layer can be stacked on the separator. The aforementioned coating method and transfer method can be used as methods for stacking the catalyst layer onto the electrode substrate.

[0184] [Application Example]

[0185] The membrane-catalyst layer structure and membrane-electrode junction of the embodiments of the present invention can be applied to fuel cells, redox flow batteries, water electrolysis devices, electrochemical hydrogen compression devices, etc. Among these, application to fuel cells and water electrolysis devices is preferred, and application to water electrolysis devices is particularly preferred. Hereinafter, application examples to water electrolysis devices are described in detail, but the present invention is not limited to these.

[0186] [Water electrolysis unit and water electrolysis device]

[0187] The water electrolysis unit of the present invention includes a membrane-electrode assembly (MEA). The interior of the water electrolysis unit is divided by a membrane into an anode (composed of an anode catalyst layer and an anode electrode substrate) and a cathode (composed of a cathode catalyst layer and a cathode electrode substrate).

[0188] Figure 1 This is a cross-sectional schematic diagram showing an example of the water electrolysis unit of the present invention. The interior of the water electrolysis unit 1 is divided into an anode 20 and a cathode 30 by a diaphragm 10. Here, the anode 20 is composed of an anode catalyst layer (not shown) and an anode electrode substrate, and the cathode 30 is composed of a cathode catalyst layer (not shown) and a cathode electrode substrate. Furthermore, it is shown that they are sandwiched between the two sides by partitions 41 and 42.

[0189] The water electrolysis apparatus is equipped with multiple water electrolysis units, and a power supply (not shown) is connected to each anode 20 and cathode 30 to apply voltage. The water electrolysis apparatus, as a basic component, includes: a water supply unit that supplies water to the water electrolysis units, an electricity supply unit that supplies electricity to the water electrolysis units, an oxygen discharge unit that discharges the generated oxygen, a hydrogen discharge unit that discharges the generated hydrogen, and a water discharge unit that discharges excess water after electrolysis.

[0190] [Water Electrolysis Method]

[0191] The water electrolysis method of this invention is performed using the water electrolysis unit and the water electrolysis apparatus of this invention. Specifically, regarding the water electrolysis method according to the embodiments of this invention, it is preferable to supply water to a water electrolysis unit internally divided into an anode and a cathode by a membrane containing a polymer electrolyte membrane, and perform electrolysis. Oxygen is generated at the anode, and hydrogen is generated at the cathode. The anode catalyst layer constituting the anode contains iridium as a catalyst, the cathode catalyst layer constituting the cathode contains platinum as a catalyst, and the membrane contains a compound N having a nitrogen-containing heterocycle. More preferably, the cathode catalyst layer contains platinum and ruthenium as catalysts. The polymer electrolyte membrane, the membrane containing the polymer electrolyte membrane, the compound N, the anode catalyst layer, and the cathode catalyst layer in this method can preferably be applied according to the description above.

[0192] The method for supplying water to the water electrolysis unit of the present invention is not particularly limited, and known methods can be used. Preferred methods for supplying water to the water electrolysis unit of the present invention include supplying water to the anode, supplying water to the cathode, and supplying water to both the anode and cathode. In the above-described water supply methods, it is preferable to supply water from outside the water electrolysis unit using a pump or similar means. In the water electrolysis method of the present invention, any of the above-described water supply methods can be used. From the viewpoint of electrolysis efficiency, it is preferable to promote the generation of oxygen and protons from the oxidation reaction of water; therefore, it is preferable to supply water at least to the anode.

[0193] Example

[0194] The present invention will be further described in detail below through examples, but the present invention is not limited thereto. It should be noted that the various measurement conditions are as follows.

[0195] (1) Molecular weight of polymer

[0196] The number-average molecular weight and weight-average molecular weight of the polymers were determined by GPC. A gel permeation chromatography apparatus was used. (Company name) manufactured HLC-8022GPC. Additionally, two columns were used as GPC pillars. TSK gelSuperHM-H (inner diameter 6.0 mm, length 15 cm) was manufactured by [Company Name]. The number-average molecular weight and weight-average molecular weight were determined using N-methyl-2-pyrrolidone solvent (10 mmol / L N-methyl-2-pyrrolidone solvent containing lithium bromide) at a flow rate of 0.2 mL / min, and converted to standard polystyrene.

[0197] (2) Ion exchange capacity (IEC)

[0198] The determination was performed using the neutralization titration methods shown in 1) to 4) below. Each determination was performed three times, and the average value was taken.

[0199] 1) After the block copolymer that had undergone proton replacement and been thoroughly washed with pure water was wiped dry, it was vacuum dried at 100°C for more than 12 hours, and the dried weight was calculated.

[0200] 2) 50 mL of 5 wt% sodium sulfate aqueous solution was added to the block copolymer and ion exchange was performed after standing for 12 hours.

[0201] 3) The generated sulfuric acid was titrated using a 0.01 mol / L sodium hydroxide aqueous solution. 0.1 w / v% of commercially available phenolphthalein solution was added as an indicator until a pale reddish-purple spot was reached as the endpoint.

[0202] 4) The IEC was obtained using the following formula.

[0203] IEC (meq / g) = [concentration of sodium hydroxide aqueous solution (mmol / ml) × amount added (ml)] / dry weight of sample (g).

[0204] (3) Determination of the thickness of the membrane and catalyst layer

[0205] Under the following conditions, the cross-sections of the diaphragm and each catalyst layer were observed using a scanning electron microscope (SEM), and the thicknesses of the diaphragm, anode catalyst layer, and cathode catalyst layer were determined from the obtained images.

[0206] Apparatus: Field Emission Scanning Electron Microscope (FE-SEM) S-4800 system)

[0207] • Accelerating voltage: 2.0kV

[0208] • Pretreatment: The cross-sectional specimens prepared by the BIB method were coated with Pt and then measured.

[0209] • BIB method: A cross-sectional sample preparation apparatus that uses an argon ion beam. A shielding plate is placed directly above the sample, and a wide beam of argon ions is irradiated from it to etch the sample, thereby creating the observation / analysis surface (cross-section).

[0210] (4) Determination of BET specific surface area of ​​carbon particles supported on catalysts such as platinum

[0211] After loading carbon particles loaded with platinum etc. into a glass container, vacuum drying was carried out at 23 °C for 16 hours. Next, the above-mentioned carbon particles loaded with platinum etc. that had been vacuum dried were loaded into a dedicated container that had been pre-dried and weighed, and pre-treatment was carried out under the following conditions. After the pre-treatment was completed, the weight of the dedicated container + the carbon particles loaded with platinum etc. was measured, and the weight of the carbon particles loaded with platinum etc. was calculated from the difference from the weight of the dedicated container. Next, the carbon particles loaded with platinum etc. after pre-treatment together with the dedicated container were installed in a measuring device, and gas adsorption measurement was carried out under the following conditions to prepare an adsorption isotherm with p / V (p 0 -p) on the vertical axis and p / p 0 on the horizontal axis. Data with p / p 0 ranging from 0.05 to 0.3 were extracted from the adsorption isotherm, and the BET specific surface area was calculated from the slope and the vertical-axis intercept of the approximate curve prepared by the least squares method.

[0212] <Pre-treatment conditions>

[0213] · Equipment: BELPREP VAC II ( manufactured by the company)

[0214] · Temperature: 100 °C

[0215] · Time: 5 hours

[0216] · Treatment atmosphere: Vacuum degassing at 10 Pa or less

[0217] <BET specific surface area measurement>

[0218] · Equipment: BELSORP-18 PLUS HT ( manufactured by the company)

[0219] · Temperature: 77 K (liquid nitrogen temperature)

[0220] · Dead volume measurement gas: He

[0221] · Adsorbate: N2

[0222] · Equilibrium setting time: 180 seconds (stable waiting time at each pressure)

[0223] · Specific surface area analysis method: BET method

[0224] <Meaning of symbols>

[0225] · V: N2 adsorption amount on the catalyst surface at each pressure

[0226] · p: Measured pressure

[0227] · p 0 : Atmospheric pressure

[0228] ·p / p 0 Relative pressure

[0229] (5) Evaluation of electrolysis performance

[0230] When evaluating the electrolytic performance of the membrane-catalyst stack, the membrane-electrode junction should be fabricated according to the following key points.

[0231] [Membrane-electrode junction]

[0232] In the examples and comparative examples, the cathode catalyst layer side stack of the membrane-catalyst stack was a commercially available gas diffusion electrode 24BCH manufactured by SGL Corporation, which was used as the cathode electrode substrate, and the anode catalyst layer side stack was a commercially available porous titanium sintered body plate, which was used as the anode electrode substrate, to create a membrane-electrode assembly.

[0233] [Water Electrolysis Method]

[0234] The membrane-electrode assembly fabricated above was placed in the JARI standard cell "Ex-1" manufactured by Ewa Co., Ltd. (electrode area 25 cm²). 2 The unit temperature was set to 60℃. Deionized water with a conductivity of less than 1 μS / cm was supplied to both the anode and cathode at a flow rate of 0.2 L / min under atmospheric pressure, with a current density of 1.5 A / cm. 2 Voltage was applied in a manner that allowed water electrolysis to be carried out over 2,000 hours.

[0235] The applied voltage was measured for electrolysis times of 0 hours and 2,000 hours, and the voltage rise rate after 2,000 hours was calculated using Equation 1 below.

[0236] Voltage rise rate (%) = (V1 - V0) / V0 × 100 ··· Equation 1

[0237] In the formula, V1 represents the applied voltage after 2,000 hours, and V0 represents the initial applied voltage (0 hours).

[0238] The lower the voltage at 0 hours (initial voltage), the higher the electrolytic performance; the lower the voltage rise rate, the less the electrolytic performance has decreased.

[0239] Synthesis of polyetherketone block copolymers (PEK blocks)

[0240] [Synthesis example 1]

[0241] (Synthesis of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane (K-DHBP) as shown in the following chemical formula (G1))

[0242] In a 500 mL flask equipped with a stirrer, thermometer, and distillation tube, 49.5 g of 4,4'-dihydroxybenzophenone, 134 g of ethylene glycol, 96.9 g of trimethyl orthoformate, and 0.50 g of p-toluenesulfonic acid monohydrate were added and dissolved. The mixture was then stirred at 78–82 °C for 2 hours. Further, the internal temperature was slowly increased to 120 °C and heated until the distillation of methyl formate, methanol, and trimethyl orthoformate completely stopped. After cooling the reaction solution to room temperature, it was diluted with ethyl acetate. The organic layer was washed with 100 mL of 5% potassium carbonate aqueous solution, separated, and the solvent was removed by distillation. 80 mL of dichloromethane was added to the residue to induce crystallization. The crystals were filtered and dried to obtain 52.0 g of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane, as shown in the following chemical formula (G1). The crystal was analyzed by GC, and the results showed that it contained 99.9% 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane and 0.1% 4,4'-dihydroxybenzophenone. The purity was 99.9%.

[0243]

[0244] [Synthesis example 2]

[0245] (Synthesis of the disodium 3,3'-disulfonated-4,4'-difluorobenzophenone shown in the following chemical formula (G2))

[0246] 109.1 g of 4,4'-difluorobenzophenone was dissolved at 100°C. (Same reagent) in 150 mL of fuming sulfuric acid (50% SO3) The reaction mixture was reacted in a solution of (a reagent) for 10 hours. Then, small batches were added to a large volume of water, neutralized with sodium hydroxide, and 200g of sodium chloride (NaCl) was added to precipitate the product. The precipitate was filtered and recrystallized from an aqueous ethanol solution to obtain the disodium salt of 3,3'-disulfonated-4,4'-difluorobenzophenone, as shown in the following chemical formula (G2). The purity was 99.3%.

[0247]

[0248] [Synthesis example 3]

[0249] (Synthesis of the nonionic oligomer a1 represented by the following general formula (G3))

[0250] In a 2,000 mL SUS polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark separator, 16.59 g of potassium carbonate (Aldrich reagent, 120 mmol), 25.83 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and 20.3 g (Aldrich reagent, 93 mmol) of 4,4'-difluorobenzophenone were added. After nitrogen purging, 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene were added. After dehydration at 150 °C, the toluene was removed by heating, and polymerization was carried out at 170 °C for 3 hours. Reprecipitation purification with a large amount of methanol yielded the terminal hydroxyl body of the nonionic oligomer a1. The number average molecular weight of the terminal hydroxyl body of the nonionic oligomer a1 was 10,000.

[0251] 1.1 g of potassium carbonate was added to a 500 mL three-necked flask equipped with a stirrer, nitrogen inlet tube, and Dean-Stark water separator. (Same reagent, 8 mmol), and 20.0 g (2 mmol) of the terminal hydroxyl group of the above nonionic oligomer a1. After nitrogen purging in the apparatus, 100 mL of NMP and 30 mL of toluene were added. After dehydration at 100 °C, the toluene was removed by heating. Further, 2.2 g (hexafluorobenzene) was added. The same reagent (12 mmol) was used, and the reaction was carried out at 105 °C for 12 hours. Reprecipitation and purification with a large amount of isopropanol yielded a nonionic oligomer a1 (terminal: fluorine group) of the following general formula (G3). The number average molecular weight was 11,000.

[0252]

[0253] [Synthesis Example 4]

[0254] (Synthesis of ionic oligomer a2 represented by the following general formula (G4))

[0255] In a 2,000 mL SUS polymerization apparatus equipped with a mixer, nitrogen inlet tube, and Dean-Stark water separator, 27.6 g of potassium carbonate was added. (Same) reagents, 200 mmol), 12.9 g (50 mmol) of K-DHBP obtained in Synthesis Example 1, and 9.3 g (4,4'-biphenyl) (Same) reagents, 50 mmol), 39.3 g (93 mmol) of 3,3'-disulfonated-4,4'-difluorobenzophenone disodium salt obtained in Synthesis Example 2, and 18-crown ether-617.9 g ( (82 mmol) was purged with nitrogen, then 300 mL of NMP and 100 mL of toluene were added. After dehydration at 150 °C, the toluene was removed by heating, and polymerization was carried out at 170 °C for 6 hours. Reprecipitation with a large amount of isopropanol yielded the ionic oligomer a2 (terminal: hydroxyl) of the following general formula (G4). The number average molecular weight was 16,000. It should be noted that in general formula (G4), M represents a hydrogen atom, Na, or K.

[0256]

[0257] (Synthesis of polyetherketone block copolymers)

[0258] In a 2,000 mL SUS polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark water separator, 16 g of ionic oligomer a2 and 11 g of nonionic oligomer a1 were added, and NMP was added to make the total amount of oligomers 7 wt%. The reaction was carried out at 105 °C for 24 hours.

[0259] Reprecipitation was carried out in a large volume of isopropanol / NMP mixture (2 / 1 by mass). The precipitate was recovered by filtration and washed with a large volume of isopropanol to obtain block copolymer b1. The polyetherketone block copolymer has a weight-average molecular weight of 340,000 and an ion exchange capacity (IEC) of 2.1 meq / g.

[0260] [Synthesis of Compound N]

[0261] Compounds (E1), (E4), (E8), (E10), (E23), (E34), (E36), (F23), (P3), and (H3) were synthesized. It should be noted that these compounds were synthesized with reference to International Publication Nos. 2014 / 08413, 2015 / 152058, and 2015 / 156228. Additionally, (F17), (F19), (P1), (H1), (H2), and the porphyrin were synthesized using commercially available products.

[0262]

[0263]

[0264]

[0265] (H1)1,10-Phenanthroline

[0266] (H2)5-Amino-1,10-Phenanthroline.

[0267] [Example 1]

[0268] [Fabrication of Polymer Electrolyte Membranes]

[0269] use" (Registered trademark) tape (Company) manufactures PET film. The 125T60 (registered trademark) was adhered and fixed to an SUS plate. 20g of the synthesized polyetherketone block copolymer was dissolved in NMP. 100mg of compound N was added to this solution as E1, and the mixture was stirred for 3 minutes to obtain a transparent solution with a polymer concentration of 13% by mass. The resulting solution was pressure filtered using a 1μm polypropylene filter, then cast onto the PET membrane and dried to obtain a membrane. Further, the membrane was subjected to proton exchange and deprotection reactions by immersion in a 10% by mass sulfuric acid aqueous solution at 80°C for 24 hours, followed by thorough washing by immersion in excess pure water for 24 hours to obtain a polymer electrolyte membrane (90μm thick). This polymer electrolyte membrane was used as a separator. The content of compound N in the separator was 0.5 parts by mass relative to 100 parts by mass of the polymer electrolyte.

[0270] [Fabrication of the Membrane-Catalyst Layer Structure]

[0271] An anode catalyst layer is stacked on one side of the polymer electrolyte membrane (diaphragm) prepared above, and a cathode catalyst layer is stacked on the other side to form a membrane-catalyst stack. The mass of iridium in the anode catalyst layer is 0.8 mg / cm³. 2 The mass of platinum in the cathode catalyst layer is 0.25 mg / cm³. 2 The thickness of each component was adjusted in a specific way.

[0272] <Anode Catalyst Layer>

[0273] Contains 10 parts by weight of catalyst particles (Elyst Ir75 0480 IrO2 catalyst manufactured by Umicore (Ir content 75%)) and fluorine-based polymer electrolyte. The total solid content is 1.3 parts by weight of "Nafion" (registered trademark) manufactured by (Company Name) (IEC=0.91 meq / g). The mass ratio of the polymeric electrolyte to the mass of iridium (Ya) is 0.17. The thickness of the anode catalyst layer is 8 μm.

[0274] <Cathode catalyst layer>

[0275] The catalyst particles include TEC61E54 carbon particles supported on a platinum-ruthenium alloy, manufactured by Tanaka Precious Metals Industry Co., Ltd. (catalyst loading rate 54% by mass, Pt / Ru mass ratio = 1 / 0.78, BET specific surface area 303 m²). 2 / g))10 parts by weight, fluorine-based polymeric electrolyte ( The catalyst layer, consisting of 4 parts by mass of "Nafion" (registered trademark) manufactured by [Company Name] (ID: D2020, IEC=0.91 meq / g), is composed entirely of solid components. The mass ratio (Yc) of the polymeric electrolyte to the total mass of platinum and ruthenium is 0.74. The thickness of this cathode catalyst layer is 12 μm.

[0276] [Comparative Example 1]

[0277] The polymer electrolyte membrane was made free of compound N, and the membrane-catalyst layer structure was prepared in the same manner as in Example 1.

[0278] [Examples 2-18]

[0279] In Example 1, the type and amount of compound N were changed as shown in Table 1. Otherwise, the same procedure as in Example 1 was followed to produce the membrane-catalyst layer structure.

[0280] [Example 19]

[0281] In Example 1, the polyetherketone block copolymer was replaced with the fluorine-based polymer electrolyte described below. Otherwise, the same procedure as in Example 1 was followed to produce the membrane-catalyst layer structure.

[0282] Fluorinated polymeric electrolytes

[0283] Used The substance obtained by NMP substitution of the solvent (water and 1-propanol) in a solution of "Nafion" (registered trademark) No. D2020 (IEC=0.91 meq / g) manufactured by (Company Name).

[0284] [Example 20]

[0285] In Example 1, the cathode catalyst layer was changed to the one described below. Otherwise, the same procedure as in Example 1 was followed to produce the membrane-catalyst layer structure.

[0286] <Cathode catalyst layer>

[0287] The catalyst particles include TEC66E50 carbon particles supported on a platinum-ruthenium alloy, manufactured by Tanaka Precious Metals Industry Co., Ltd. (catalyst loading rate 50% by mass, Pt / Ru mass ratio = 1 / 0.52, BET specific surface area 312 m²). 2 / g))10 parts by weight, fluorine-based polymeric electrolyte ( The catalyst layer, consisting of 4 parts by weight of "Nafion" (registered trademark) No. D2020 manufactured by (Company Name), is composed entirely of solid components. The mass ratio (Yc) of the polymeric electrolyte to the total mass of platinum and ruthenium is 0.8. The thickness of this cathode catalyst layer is 11 μm.

[0288] [Example 21]

[0289] In Example 1, the cathode catalyst layer was changed to the one described below. Otherwise, the same procedure as in Example 1 was followed to produce the membrane-catalyst layer structure.

[0290] <Cathode catalyst layer>

[0291] The catalyst particles include carbon particles TEC62E58-HT, supported on a platinum-ruthenium alloy and manufactured by Tanaka Precious Metals Industry Co., Ltd. (catalyst loading rate 58% by mass, Pt / Ru mass ratio = 1 / 1.04, BET specific surface area 285 m²). 2 / g))10 parts by weight, fluorine-based polymeric electrolyte ( The catalyst layer, consisting of 4 parts by weight of "Nafion" (registered trademark) D2020 manufactured by (Company Name), is composed entirely of solid components. The mass ratio (Yc) of the polymeric electrolyte to the combined mass of platinum and ruthenium is 0.69. The thickness of this cathode catalyst layer is 13 μm.

[0292] [Example 22]

[0293] In Example 1, the cathode catalyst layer was changed to the one described below. Otherwise, the same procedure as in Example 1 was followed to produce the membrane-catalyst layer structure.

[0294] <Cathode catalyst layer>

[0295] The catalyst particles include carbon particles TEC61E54-HT2 supported on a platinum-ruthenium alloy, manufactured by Tanaka Precious Metals Industry Co., Ltd. (catalyst loading rate 54% by mass, Pt / Ru mass ratio = 1 / 0.78, BET specific surface area 295 m²). 2 / g))10 parts by weight, fluorine-based polymeric electrolyte ( The catalyst layer, consisting of 4 parts by mass of "Nafion" (registered trademark) manufactured by [Company Name] (ID: D2020, IEC=0.91 meq / g), is composed entirely of solid components. The mass ratio (Yc) of the polymeric electrolyte to the total mass of platinum and ruthenium is 0.74. The thickness of this cathode catalyst layer is 12 μm.

[0296] [Example 23]

[0297] In Example 1, the cathode catalyst layer was changed to the one described below. Otherwise, the same procedure as in Example 1 was followed to produce the membrane-catalyst layer structure.

[0298] <Cathode catalyst layer>

[0299] The catalyst particles include carbon particles TEC61V54-HT2 supported on a platinum-ruthenium alloy, manufactured by Tanaka Precious Metals Industry Co., Ltd. (catalyst loading rate 54% by mass, Pt / Ru mass ratio = 1 / 0.78, BET specific surface area 90 m²). 2 / g))10 parts by weight, fluorine-based polymeric electrolyte ( The catalyst layer, consisting of 4 parts by mass of "Nafion" (registered trademark) manufactured by [Company Name] (ID: D2020, IEC=0.91 meq / g), is composed entirely of solid components. The mass ratio (Yc) of the polymeric electrolyte to the total mass of platinum and ruthenium is 0.74. The thickness of this cathode catalyst layer is 10 μm.

[0300] [Example 24]

[0301] In Example 1, the cathode catalyst layer was changed to the one described below. Otherwise, the same procedure as in Example 1 was followed to produce the membrane-catalyst layer structure.

[0302] <Cathode catalyst layer>

[0303] The catalyst particles include carbon particles (TEC66V50-HT2, supported on a platinum-ruthenium alloy and manufactured by Tanaka Precious Metals Industry Co., Ltd., with a catalyst loading of 50% by mass, a Pt / Ru mass ratio of 1 / 0.52, and a BET specific surface area of ​​94 m²). 2 / g))10 parts by weight, fluorine-based polymeric electrolyte ( The catalyst layer, consisting of 4 parts by weight of "Nafion" (registered trademark) No. D2020 manufactured by (Company Name), is composed entirely of solid components. The mass ratio (Yc) of the polymeric electrolyte to the combined mass of platinum and ruthenium is 0.8. The thickness of this cathode catalyst layer is 9 μm.

[0304] [Comparative Example 2]

[0305] In Example 1, the cathode catalyst layer was changed to the one described below. Otherwise, the same procedure as in Example 1 was followed to produce the membrane-catalyst layer structure.

[0306] <Cathode catalyst layer>

[0307] Catalyst particles (Tanaka Precious Metals Industry Co., Ltd.) containing platinum-supported carbon particles TEC10E50E (platinum loading 50% by mass, BET specific surface area 375 m²) 2 / g))10 parts by weight, fluorine-based polymeric electrolyte ( The catalyst layer, consisting of 4 parts by weight of "Nafion" (registered trademark) No. D2020 manufactured by (Company Name), is composed entirely of solid components. The mass ratio (Yc) of the polymeric electrolyte to the platinum element is 0.8. The thickness of this cathode catalyst layer is 6 μm.

[0308] [Comparative Example 3]

[0309] In Comparative Example 2, the anode catalyst layer was changed to the one described below. Otherwise, the same procedure as in Comparative Example 2 was followed to fabricate the membrane-catalyst layer structure. The mass of platinum in this anode catalyst layer was 0.3 mg / cm³. 2 The thickness was adjusted in this way.

[0310] <Anode Catalyst Layer>

[0311] Contains 10 parts by mass of catalyst particles (TC10E50E platinum-supported carbon particles manufactured by Tanaka Precious Metals Industry Co., Ltd. (platinum loading rate 50% by mass)) and fluorine-based polymer electrolyte ( The catalyst layer, consisting of 4 parts by weight of "Nafion" (registered trademark) No. D2020 manufactured by (Company Name), is composed entirely of solid components. The mass ratio of the polymeric electrolyte to the combined mass of platinum and ruthenium is 0.8. The thickness of this anode catalyst layer is 7 μm.

[0312] [Example 25]

[0313] In Example 1, the anode catalyst layer was changed to the one described below. Otherwise, the same procedure as in Example 1 was followed to produce the membrane-catalyst layer structure.

[0314] <Anode Catalyst Layer>

[0315] Contains 10 parts by weight of iridium oxide (Umicore's IrO2 catalyst Elyst Ir75 0480 (Ir content 75%)), 1.5 parts by weight of commercially available platinum particles (converted to platinum element), and a fluorine-based polymer electrolyte. The total solid component is 1.3 parts by weight of "Nafion" (registered trademark) manufactured by (Company Name) (D2020). The mass ratio of the polymeric electrolyte to the mass of iridium (Ya) is 0.17. The thickness of the anode catalyst layer is 9 μm.

[0316] [Example 26]

[0317] In Example 14, the anode catalyst layer was changed to the one described below. Otherwise, the same procedure as in Example 14 was followed to produce the membrane-catalyst layer structure.

[0318] <Anode Catalyst Layer>

[0319] Contains 10 parts by weight of catalyst particles (Elyst Ir75 0480 IrO2 catalyst manufactured by Umicore (Ir content 75%)) and fluorine-based polymer electrolyte. The total solid content consists of 4.5 parts by weight of "Nafion" (registered trademark) manufactured by (Company Name) (D2020). The mass ratio of the polymeric electrolyte to the mass of iridium (Ya) is 0.60. The thickness of the anode catalyst layer is 11 μm.

[0320] [Example 27]

[0321] In Example 1, the mass of platinum in the cathode catalyst layer was changed to 0.15 mg / cm³. 2 Otherwise, the same procedure as in Example 1 was followed to fabricate the membrane-catalyst layer structure. The thickness of the cathode catalyst layer was 7 μm.

[0322] [Example 28]

[0323] In Example 14, the mass of platinum in the cathode catalyst layer was changed to 0.55 mg / cm³. 2 Otherwise, the same procedure as in Example 14 was followed to fabricate the membrane-catalyst layer structure. The thickness of the cathode catalyst layer was 26 μm.

[0324] [evaluate]

[0325] The electrolytic performance of the membrane-catalyst layer structures prepared in the above examples and comparative examples was evaluated using the method described in (4) above. The results are shown in Table 1.

[0326] [Table 1]

[0327]

[0328] [Example 29]

[0329] The material obtained by laminating the following protective layer (10 μm thick) onto one side of the polymer electrolyte membrane of Example 1 was used as a separator. A cathode catalyst layer was laminated on the protective layer side of the separator, and an anode catalyst layer was laminated on the polymer electrolyte membrane side. Otherwise, the membrane-catalyst layer structure was fabricated in the same manner as in Example 1. The content of compound N was 0.46 parts by mass relative to 100 parts by mass of the polymer electrolyte (the combined amount of the PEK block of the polymer electrolyte membrane and the fluorinated polymer electrolyte of the protective layer) contained in the separator.

[0330] <Protective Layer>

[0331] Contains 10 parts carbon black (Cabot Corporation's "VULCAN" (registered trademark) XC72), fluorine-based polymeric electrolyte ( (Nafion Co., Ltd.) (registered trademark number D2020) 8 parts by weight as all solid components.

[0332] [Example 30]

[0333] In Example 29, compound N(E1) was not added to the polymeric electrolyte membrane but was added to the protective layer. Otherwise, the membrane-catalyst layer structure was fabricated in the same manner as in Example 26. To add compound N(E1) to the protective layer, a fluorinated polymeric electrolyte (…) was used. This substance is obtained by NMP substitution of the solvent (water and 1-propanol) in the solution of "Nafion" (registered trademark) manufactured by (Company) under registration number D2020. It should be noted that the amount of compound N added was adjusted to 0.1 parts by mass relative to 100 parts by mass of the polymer electrolyte contained in the membrane (the total amount of the PEK block of the polymer electrolyte membrane and the fluorinated polymer electrolyte in the protective layer).

[0334] [Example 31]

[0335] <Fabrication of Polymer Electrolyte Membranes>

[0336] use" (Registered trademark) tape (Company) manufactures PET film. The 125T60 (registered trademark) was adhered and fixed to the SUS plate. A solution (polymer concentration 13% by mass) obtained by dissolving the synthesized polyetherketone block copolymer in NMP was cast and coated onto the PET film, and a porous substrate (mesh fabric) was impregnated onto it. Then, a solution obtained by dissolving 20g of the synthesized polyetherketone block copolymer and 300mg of compound N(E4) in NMP was coated onto the porous substrate, and dried to obtain a membrane. Further, the membrane was subjected to proton exchange and deprotection reactions by immersing it in a 10% by mass sulfuric acid aqueous solution at 80°C for 24 hours, followed by thorough cleaning by immersion in excess pure water for 24 hours to obtain a polymer electrolyte membrane (70μm thick).

[0337] This polymeric electrolyte membrane is composed of three layers: a composite layer containing a porous substrate and a polymeric electrolyte, and two non-composite layers containing polymeric electrolyte but not a porous substrate on each side. The thickness of each layer, from the PET film side, is: "Non-composite layer 1 (thickness 15 μm) / Composite layer (thickness 35 μm) / Non-composite layer 2 (thickness 20 μm)". In this polymeric electrolyte membrane, compound N is only contained in non-composite layer 2. The content of compound N in this polymeric electrolyte membrane is 0.1 parts by mass relative to 100 parts by mass of polymeric electrolyte.

[0338] [Porous substrate]

[0339] The mesh fabric made of liquid crystal polyester fiber manufactured in Manufacturing Example 1 of International Publication No. 2019 / 188960 was used.

[0340] [Fabrication of the Membrane-Catalyst Layer Structure]

[0341] A membrane-catalyst stack is formed by stacking the anode catalyst layer of Example 1 on the non-composite layer 1 side of the polymer electrolyte membrane (diaphragm) prepared above, and stacking the cathode catalyst layer of Example 1 on the non-composite layer 2 side.

[0342] [evaluate]

[0343] The electrolytic performance of the membrane-catalyst layer structures prepared in the above examples and comparative examples was evaluated. The results are shown in Table 2.

[0344] [Table 2]

[0345]

[0346] Symbol Explanation

[0347] 1 Water Electrolysis Unit

[0348] 10 diaphragms

[0349] 20 First catalyst layer

[0350] 30 Second catalyst layer

[0351] 41, 42 partitions.

Claims

1. A membrane-catalyst layer structure, wherein, The first catalyst layer and the second catalyst layer are sandwiched between opposing membranes containing at least a polymer electrolyte membrane. The first catalyst layer and the second catalyst layer contain platinum and / or iridium as the first metal. The first catalyst layer and / or the second catalyst layer further comprise at least one element selected from gold, silver, copper, nickel, palladium, cobalt, rhodium, iron, ruthenium, and osmium as a second metal. The membrane contains a compound N having a nitrogen-containing heterocycle.

2. The membrane-catalyst layer structure according to claim 1, wherein the compound N having a nitrogen-containing heterocycle comprises a nitrogen-containing aromatic five-membered ring or a nitrogen-containing aromatic six-membered ring.

3. The membrane-catalyst layer structure according to claim 1 or 2, wherein the compound N having a nitrogen-containing heterocycle comprises a nitrogen-containing aromatic six-membered ring.

4. The membrane-catalyst layer structure according to any one of claims 1 to 3, wherein the compound N having a nitrogen-containing heterocycle comprises a plurality of nitrogen-containing aromatic six-membered rings.

5. The membrane-catalyst layer structure according to any one of claims 1 to 4, wherein the compound N having a nitrogen-containing heterocycle is selected from general formulas (D1), (D2), and (D3). In equation (D1), R 1 It represents at least one group selected from the group consisting of divalent or higher hydrocarbon groups, amino groups, thioether groups, ketone groups, sulfonyl groups, sulfone groups, and ether groups, where n = 1 Q. 1 Each of these can be independently represented as a five-membered or six-membered nitrogen-containing aromatic heterocycle, a fused ring formed by these nitrogen-containing aromatic heterocycles, or a fused ring formed by these nitrogen-containing aromatic heterocycles and a hydrocarbon aromatic ring. These nitrogen-containing aromatic heterocycles and hydrocarbon aromatic rings can be substituted with any substituents, and n1 represents an integer from 2 to 10. In equation (D2), R 2 Q represents at least one group selected from hydrocarbon, amino, thioether, ketone, sulfonyl, sulfone, and ether groups, or directly bonded. 2 This refers to a group consisting of 1 to 5 nitrogen-containing aromatic heterocycles (five- or six-membered rings), fused rings formed by these nitrogen-containing aromatic heterocycles, or fused rings formed by these nitrogen-containing aromatic heterocycles and hydrocarbon aromatic rings, respectively. Both the nitrogen-containing aromatic heterocycles and the hydrocarbon aromatic rings can be substituted with any substituents. n2 represents an integer from 1 to 20. X 1 and X 2 Each of these groups independently represents at least one group selected from the following: hydrogen atom, halogen group, hydrocarbon group, alkoxy group, aryloxy group, carboxyl group, carboxylic acid ester group, phosphonyl group, phosphonic acid group, phosphate ester group, sulfonic acid group, sulfate ester group, hydroxyl group, amino group, cyano group, and nitro group. In formula (D3), R 3 C(R) represents a nitrogen atom, R represents a hydrogen atom or an alkyl group, and Q represents a nitrogen atom. 3 The symbol represents a nitrogen-containing aromatic heterocycle with a five- or six-membered ring, a fused ring formed by these nitrogen-containing aromatic heterocycles, or a fused ring formed by these nitrogen-containing aromatic heterocycles and a hydrocarbon aromatic ring, wherein these nitrogen-containing aromatic heterocycles and the hydrocarbon aromatic ring may be substituted by any substituent, and g represents an integer from 5 to 500.

6. The membrane-catalyst layer structure according to any one of claims 1 to 5, wherein the first catalyst layer is an oxygen evolution catalyst layer containing iridium as the first metal, and the second catalyst layer is a proton reduction catalyst layer containing platinum as the first metal.

7. The membrane-catalyst layer structure according to any one of claims 1 to 5, wherein the first catalyst layer is an oxygen reduction catalyst layer containing platinum as the first metal, and the second catalyst layer is a hydroxide catalyst layer containing platinum as the first metal.

8. The membrane-catalyst layer structure according to claim 6, wherein the second catalyst layer comprises ruthenium as a second metal.

9. The membrane-catalyst layer structure according to claim 6 or 8, wherein the second catalyst layer comprises carbon particles supported on platinum, or carbon particles supported on platinum and ruthenium.

10. The membrane-catalyst layer structure according to claim 8 or 9, wherein the second catalyst layer comprises carbon particles supported on a platinum-ruthenium alloy.

11. The membrane-catalyst layer structure according to any one of claims 1, 6, 8 to 10, wherein the first catalyst layer comprises iridium as a first metal, and iridium oxide is included as the iridium element.

12. The membrane-catalyst layer structure according to any one of claims 1 to 11, wherein the first catalyst layer and the second catalyst layer further comprise a polymeric electrolyte.

13. The membrane-catalyst layer structure according to any one of claims 1, 6, 8 to 12, wherein the first catalyst layer comprises iridium as a first metal and a polymeric electrolyte, the mass ratio of the polymeric electrolyte to the mass of the iridium element Ya is 0.05 or more and less than 0.5, and the second catalyst layer comprises platinum as a first metal, ruthenium as a second metal, and a polymeric electrolyte, the mass ratio of the polymeric electrolyte to the total mass of the platinum element and the ruthenium element Yc is 0.25 or more and less than 1.

1.

14. The membrane-catalyst layer structure according to claim 13, wherein the proportion Ya is less than the proportion Yc.

15. The membrane-catalyst layer structure according to any one of claims 1 to 14, wherein the thickness of the first catalyst layer and / or the second catalyst layer is 25% or less relative to 100% of the thickness of the membrane.

16. The membrane-catalyst layer structure according to any one of claims 1 to 15, wherein the polymeric electrolyte membrane comprises a hydrocarbon-based polymeric electrolyte.

17. The membrane-catalyst layer structure according to claim 1 or 7, wherein the first catalyst layer is an anode catalyst layer and the second catalyst layer is a cathode catalyst layer.

18. A fuel cell comprising the membrane-catalyst layer structure according to any one of claims 1 to 17.

19. A water electrolysis apparatus comprising the membrane-catalyst layer structure according to any one of claims 1 to 17.

20. A membrane-electrode assembly, which is formed by disposing electrode substrates on both sides of a membrane-catalyst layer structure according to any one of claims 1 to 17.

21. A fuel cell comprising the membrane-electrode assembly of claim 20.

22. A water electrolysis unit comprising the membrane-electrode junction of claim 20.

23. A water electrolysis apparatus comprising the water electrolysis unit of claim 22.

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