Catalyst

Abstract

To provide a catalyst containing organic nitrogen compounds capable of suppressing the occurrence of cracks in the catalyst layer.SOLUTION: The catalyst contains metal particles having oxygen reduction activity, an additive having basic functional groups, and a binder having acidic functional groups. The additive is at least one organic nitrogen compound, and the ratio of the total amount of basic functional groups of the additive to the total amount of acidic functional groups of the binder (amount of basic sites / amount of acid sites) is greater than 0 and 6.82 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a catalyst.

Background Art

[0002] Various studies have been conducted on catalysts for electrochemical oxygen reduction. Patent Document 1 discloses a catalyst for electrochemical oxygen reduction, which contains nanoparticles containing platinum and at least one selected from the group consisting of a melamine compound, a thiocyanuric acid compound, and a polymer having the melamine compound or the thiocyanuric acid compound as a monomer. Patent Document 2 discloses a catalyst for electrochemical oxygen reduction, which contains nanoparticles containing platinum and at least one selected from the group consisting of a specific polymer having a melamine compound as a monomer and a specific melamine compound, and has high durability at 70 - 85°C as practical temperature conditions.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When an organic nitrogen compound is added as an additive to a catalyst having oxygen reduction activity to improve the catalyst performance, cracks may occur in the catalyst layer.

[0005] In view of the above circumstances, the present disclosure is made, and the main object thereof is to provide a catalyst that contains an organic nitrogen compound and can suppress the occurrence of cracks in the catalyst layer.

Means for Solving the Problems

[0006] In the present disclosure, there are provided metal particles having oxygen reduction activity, an additive having a basic functional group, and a binder having an acidic functional group, wherein the additive is at least one kind of organic nitrogen compound, and a catalyst is provided, wherein a ratio (base point amount / acid point amount) of the total basic functional group amount of the additive to the total acidic functional group amount of the binder is greater than 0 and 6.82 or less.

[0007] In the catalyst of the present disclosure, the organic nitrogen compound may be a monomer represented by the following general formula (1), or a polymer containing at least a part of the monomer.

[0008] [Chemical formula]

[0009] [In general formula (1), R1, R2, and R3 are each one kind of functional group selected from the group consisting of a hydrogen atom, a halogen atom, or a nitrile group, an amide group, an imine group, an amino group, a thiol group, a hydroxyl group, a sulfo group, a carboxylic acid group, a phosphoric acid group, a ketone group, an aldehyde group, an ester group, an alkoxy group, a phenol group, a cyclopentyl group, a cyclohexyl group, an alkylamino group having 1 to 10 carbon atoms, an alkylsulfonic acid group having 1 to 10 carbon atoms, a perfluoroalkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkenylamino group having 1 to 10 carbon atoms, an alkenylsulfonic acid group having 1 to 10 carbon atoms, a perfluoroalkenyl group having 1 to 10 carbon atoms, and an alkenyl group having 1 to 10 carbon atoms, and each of the functional groups may have at least one selected from the group consisting of at least one kind of functional group selected from the above functional group group, an aromatic ring, a heterocyclic ring, an oxygen atom, a sulfur atom, a nitrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and a hydrogen atom in the molecular chain.]

[0010] In the catalyst of the present disclosure, the metal particles may be at least one selected from the group consisting of platinum particles, platinum alloy particles, and composite particles containing platinum.

[0011] In the catalyst of the present disclosure, it further includes a carrier, The metal particles may be supported on the carrier.

[0012] In the catalyst of the present disclosure, the weight of the additive relative to the weight of the carrier may be 0.0100 or more and 0.150 or less.

[0013] In the catalyst of the present disclosure, the weight of the binder relative to the weight of the carrier may be 0.700 or more and 1.15 or less.

[0014] In the catalyst of the present disclosure, the binder is a perfluorocarbon sulfonic acid polymer, The equivalent mass per mole of acidic functional groups of the binder may be 600 g / mol or more and 1100 g / mol or less.

[0015] In the catalyst of the present disclosure, the additive is oleylamine, melamine, or a polymer of melamine, The equivalent mass per mole of basic functional groups of the additive may be 21.0 g / mol or more and 267 g / mol or less.

[0016] In the present disclosure, there is provided an air electrode for a fuel cell or a metal-air battery, including the catalyst.

[0017] In the present disclosure, there is provided a fuel cell having the air electrode as a cathode.

[0018] In the present disclosure, there is provided a metal-air battery having the air electrode as a cathode.

Advantages of the Invention

[0019] The present disclosure can provide a catalyst that contains an organic nitrogen compound and can suppress the occurrence of cracks in the catalyst layer.

Modes for Carrying Out the Invention

[0020] Hereinafter, embodiments according to the present disclosure will be described. Matters other than those specifically mentioned in this specification and necessary for the implementation of the present disclosure (for example, general configurations and manufacturing processes of catalysts that do not characterize the present disclosure) can be grasped as design matters of those skilled in the art based on the prior art in the relevant field. The present disclosure can be implemented based on the content disclosed in this specification and common general knowledge in the art. In this specification, "~" indicating a numerical range is used to mean that the numerical values described before and after it are included as the lower limit value and the upper limit value. Also, any combination of the upper limit value and the lower limit value in the numerical range can be adopted.

[0021] 1. Catalyst In the present disclosure, there are metal particles having oxygen reduction activity, an additive having a basic functional group, and a binder having an acidic functional group, wherein the additive is at least one kind of organic nitrogen compound, and a catalyst is provided, characterized in that the ratio of the total amount of basic functional groups of the additive to the total amount of acidic functional groups of the binder (basic point amount / acid point amount) is greater than 0 and not more than 6.82.

[0022] Cracking of the catalyst layer directly leads to problems such as reducing the durability of the product, lowering the yield of the product, and being unable to fabricate a membrane-electrode assembly. Cracking of the catalyst layer is because the organic nitrogen compound as an additive binds to the binder having an acidic functional group, thereby inhibiting the function of the binder to bind the catalyst layer. The organic nitrogen compound has a basic functional group, and the binder has an acidic functional group. Due to the acid-base interaction, the two form a bond. The binder originally has the function of preventing cracking of the catalyst layer and promoting the binding between primary particles and secondary particles of the catalyst by interacting with the metal contained in the catalyst and its support (carrier). The addition of the organic nitrogen compound inhibits the function of the binder and induces cracking of the catalyst layer. By controlling the ratio of the total amount of acidic functional groups and the total amount of basic functional groups contained in the catalyst, cracking of the catalyst layer can be suppressed, the yield of the product can be increased, and the durability of the product can be increased.

[0023] The catalyst of the present disclosure includes metal particles having oxygen reduction activity, an additive having basic functional groups, and a binder having acidic functional groups.

[0024] The additive has basic functional groups. The additive is at least one kind of organic nitrogen compound. As the organic nitrogen compound, a compound having a nitrogen equivalent representing the dry weight per mole of nitrogen may satisfy 20 to 270 g·eq -1 and may also be a compound satisfying 20 to 70 g·eq -1 . The nitrogen equivalent can be calculated from the following formula. In the case of a polymer, the nitrogen equivalent of the monomer is regarded as the nitrogen equivalent of the polymer. Nitrogen equivalent (g·eq -1 ) = molecular weight (g / mol) ÷ amount of nitrogen substance in the molecule (mol N / mol) As the organic nitrogen compound, it may be a compound having an amine functional group, a compound having pyridine-type nitrogen, or a compound containing a triazine ring. As the organic nitrogen compound, it may be a monomer represented by the following general formula (1) or a polymer containing at least a part of the monomer.

[0025]

Chemical formula

[0026] In general formula (1), R1, R2, and R3 are each a hydrogen atom, a halogen atom, or a functional group selected from the group consisting of a nitrile group, an amide group, an imine group, an amino group, a thiol group, a hydroxyl group, a sulfo group, a carboxylic acid group, a phosphoric acid group, a ketone group, an aldehyde group, an ester group, an alkoxy group, a phenol group, a cyclopentyl group, a cyclohexyl group, an alkylamino group having 1 to 10 carbon atoms, an alkylsulfonic acid group having 1 to 10 carbon atoms, a perfluoroalkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkenylamino group having 1 to 10 carbon atoms, an alkenylsulfonic acid group having 1 to 10 carbon atoms, a perfluoroalkenyl group having 1 to 10 carbon atoms, and an alkenyl group having 1 to 10 carbon atoms, and each of the functional groups may have at least one selected from the group consisting of at least one functional group selected from the above functional group group, an aromatic ring, a heterocyclic ring, an oxygen atom, a sulfur atom, a nitrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and a hydrogen atom in the molecular chain.

[0027] In general formula (1), R1, R2, and R3 may each be a primary amine, a secondary amine, a tertiary amine, or a quaternary ammonium cation.

[0028] Examples of the organic nitrogen compound include a melamine compound (nitrogen equivalent: 21 g·eq -1 ), a thiocyanuric acid compound (nitrogen equivalent: 59 g·eq -1 ), a cyanuric acid compound (nitrogen equivalent: 34 g·eq -1 ), oleylamine (nitrogen equivalent: 267 g·eq -1 ), tetradecylamine (nitrogen equivalent: 213 g·eq -1 ), 2,4,6-Tris[bis(methoxymetyl)amino]-1,3,5-triazine (nitrogen equivalent: 65 g·eq -1 ), 6-(Dibutylamino)-1,3,5-triazine-2,4-dithiol (nitrogen equivalent: 68 g·eq -1 ), 2,4-Diamino-6-butylamino-1,3,5-triazine (nitrogen equivalent: 30 g eq-1 )、 2,4,6-Tris(pentafluoroethyl)-1,3,5-triazine (nitrogen equivalent 145 g·eq -1 ), and polymers using these as monomers, and Poly(melamine-co-formaldehyde)methylated (nitrogen equivalent 20~40 g·eq -1 ), and Poly(melamine-co-formaldehyde)isobutylated (nitrogen equivalent 20~40 g·eq -1 ) etc. may be used. Also, two or more of the aforementioned additives may be included. As the melamine compound, melamine, derivatives of melamine, etc. may be used. As the thiocyanuric acid compound, thiocyanuric acid, derivatives of thiocyanuric acid, etc. may be used. As the cyanuric acid compound, cyanuric acid, derivatives of cyanuric acid, etc. may be used. As the polymer using a melamine compound, a thiocyanuric acid compound, or a cyanuric acid compound as a monomer, examples include melamine resin, thiocyanuric acid resin, or cyanuric acid resin having the above-mentioned melamine compound, thiocyanuric acid compound, or cyanuric acid compound in the main chain of the repeating unit. Among the above, as the additive, oleylamine, melamine (1,3,5-triazine-2,4,6-triamine), or polymers thereof may be used. In the case of a polymer, after adsorption to metal particles, it becomes more difficult to desorb compared to the monomer case, so the adsorption stability is improved. The degree of polymerization of the polymer may be in the range of 1 to 10,000.

[0029] The equivalent mass per mole of the basic functional group of the additive may be 21.0 g / mol or more and 267 g / mol or less.

[0030] The metal particles may be any metal having oxygen reduction activity (oxygen reduction catalytic ability), such as platinum, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, and yttrium, and two or more of these metals may be used. Further, the metal may be an oxide, nitride, sulfide, phosphide, or the like. Among the above, the metal particles may be at least one selected from the group consisting of platinum particles, platinum alloy particles, and composite particles containing platinum. The metals other than platinum contained in the platinum alloy and the composite particles containing platinum are, for example, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, and yttrium, and may contain two or more of these metals. The elemental ratio of the metal other than platinum in the platinum alloy is not particularly limited and may be 0.11 to 50 atm%. The particle diameter (grain size) of the metal particles is not particularly limited and may be 1 to 100 nm.

[0031] In the present disclosure, the grain size of the particles is the average crystallite size measured by the X-ray diffraction method. The grain size of the particles may be measured by an electron microscope for the grain sizes of 100 to 1000 particles, and the average value thereof may be used as the average grain size of the particles. In the present disclosure, the grain size was measured by the above two methods.

[0032] The catalyst of the present disclosure may contain a carrier such as carbon and an oxide. The metal particles are supported on the carrier. The method for supporting the metal particles on the carrier is not particularly limited, and a conventionally known method can be appropriately employed. The carrier may be primary particles or secondary particles. The particle size of the primary particles of the carrier may be, for example, 5 to 500 nm. The metal loading ratio of the metal particles supported on the carrier is not particularly limited and may be 1 to 60%, or may be 18 to 48%. The carrier may be conductive carbon, an oxide, or a mixture containing at least two of these. The carbon may be carbon black (acetylene black, ketjen black, channel black, roller black, disk black, oil furnace black, gas furnace black, lamp black, thermal black, and VULCAN (registered trademark) - based carbon, etc.), activated carbon, graphite, glassy carbon, graphite, graphene, carbon fiber, carbon nanotube, carbon nitride, carbon sulfide, and carbon phosphide, or a mixture containing at least two of these. The oxide may be titanium oxide, niobium oxide, tin oxide, tungsten oxide, and molybdenum oxide, or a mixture containing at least two of these.

[0033] The binder may be any one having an acidic functional group. The binder may be a polyelectrolyte. The polyelectrolyte may be an electrolyte, an ionomer, or sometimes called an ionomer. In the present disclosure, it is hereinafter referred to as a binder. The binder may have sulfonic acid, phosphoric acid, etc. as acidic functional groups. The binder may be a perfluorocarbon sulfonic acid polymer, an anion exchange polymer, or a polymer mainly composed of polyether ether ketone, polybenzimidazole, etc.

[0034] The equivalent mass per mole of the acidic functional group of the binder may be 600 g / mol or more and 1100 g / mol or less.

[0035] [Base point amount / Acid point amount] In the catalyst of the present disclosure, the ratio of the total basic functional group amount of the additive to the total acidic functional group amount of the binder (basic point amount / acidic point amount) is greater than 0 and 6.82 or less. The ratio of the basic point amount to the acidic point amount is defined as (total basic functional group amount in the additive) / (total acidic functional group amount in the binder). The basic point amount / acidic point amount may be calculated from the following formula. Basic point amount / acidic point amount (-) = ((Ratio of additive weight to carrier weight (-) ÷ Equivalent mass per mole of basic functional group of the additive (g / mol))) ÷ ((Ratio of binder weight to carrier weight (-) ÷ Equivalent mass per mole of acidic functional group of the binder (g / mol))) The type of basic functional group serving as the basic point is not particularly limited, and may be an amine group such as an aliphatic amine group and an aromatic amine group, and a pyridine group, an imine group, a nitrile group, a pyrrole group, etc. The type of acidic functional group serving as the acidic point is not particularly limited, and may be a sulfonic acid group, a phosphoric acid group, etc.

[0036] [Additive weight relative to carrier weight] In the catalyst of the present disclosure, the weight of the additive relative to the weight of the carrier may be 0.0100 or more and 0.150 or less. The additive weight relative to the carrier weight is defined as (additive weight) / (carrier weight).

[0037] [Binder weight relative to carrier weight] In the catalyst of the present disclosure, the weight of the binder relative to the weight of the carrier may be 0.700 or more and 1.15 or less. The binder weight relative to the carrier weight is defined as (binder weight) / (carrier weight).

[0038] [Additive weight evaluation method] Evaluation methods for the weight of the additive contained in the catalyst of the present disclosure include a method of measuring the nitrogen content by CHN elemental analysis, a method of extracting the additive from the catalyst and directly measuring the additive, etc. The method for measuring the nitrogen content by CHN elemental analysis is a method for quantifying the amounts of carbon, hydrogen, and nitrogen atoms contained in a sample by quantifying carbon dioxide, water, and nitrogen oxides generated after burning the sample with oxygen for a certain period of time. By comparing the nitrogen amounts in the samples before and after introducing the additive, it is possible to evaluate the amount of the additive. The method for extracting the additive from the oxygen reduction catalyst and directly measuring the additive is a method for qualitatively and quantitatively analyzing the additive after extracting the additive with a solvent that dissolves the additive contained in the catalyst. As analytical methods, there are chromatography, ultraviolet-visible spectroscopy (UV-vis), infrared spectroscopy (IR), nuclear magnetic resonance (NMR), and the like.

[0039] [Evaluation Methods for Metal Particle Weight, Carrier Weight, and Binder Weight] Evaluation methods for the weight of metal particles, the weight of the carrier, and the weight of the binder contained in the catalyst of the present disclosure include thermogravimetric analysis (TG) and inductively coupled plasma optical emission spectroscopy (ICP). Thermogravimetric analysis (TG) is a method for measuring the weight when changing the gas atmosphere, temperature, etc. It is a measurement method in which, after raising the temperature and burning moisture, a conductive carrier, a polymer having an ion exchange group, and impurities, the remaining weight is taken as the metal particle weight. Inductively coupled plasma optical emission spectroscopy (ICP) is a method for qualitatively and quantitatively analyzing the contained elements from the wavelength and intensity of the emission lines emitted by atoms excited by plasma. It is possible to calculate the weight of any substance by controlling the measurement temperature and gas atmosphere. It is possible to directly quantify the weight of metal particles, the weight of the carrier, and the weight of the binder contained in the catalyst.

[0040] The catalyst of the present disclosure may be used for a fuel cell or a metal-air battery. The catalyst of the present disclosure may be used for the cathode of a fuel cell, the anode of a fuel cell, or the air electrode of a metal-air battery. Further, the catalyst of the present disclosure may be used for the anode for water electrolysis, which is the reverse reaction of a fuel cell, the cathode for water electrolysis, the anode for CO2 reduction, or the cathode for CO2 reduction.

[0041] The shape of the catalyst of the present disclosure may be layered. That is, the catalyst of the present disclosure may be a catalyst layer. Examples of the catalyst layer formation method include the following methods.

[0042] [Catalyst Ink Preparation Step] First, a predetermined amount of a carrier supporting metal particles (metal particle-supported carrier), a binder, an additive, and a solvent are put into a container, and these are stirred using a stirrer to prepare a catalyst ink. The solvent type is not particularly limited, and any liquid can be used, such as water, alcohol, or a mixed solution of at least one alcohol and water. Examples of the alcohol include methanol, diacetone alcohol, ethanol, 1-propanol, 2-propanol, tert-butyl alcohol, ethylene glycol, propylene glycol, and the like. Examples of the stirrer include a ball mill such as an ultrasonic homogenizer, a jet mill, and a bead mill, a high shear, and a filmix. The stirring conditions such as the stirring speed, stirring time, and rotation speed are not particularly limited and can be set as appropriate. Thereafter, a vacuum degassing treatment is performed and left standing for one day. The standing time is not limited and can be set arbitrarily. It is also possible to use it without standing. Further, a vacuum degassing treatment may be performed again.

[0043] [Catalyst Ink Coating Step] The prepared catalyst ink is coated on a substrate, and the solvent is removed after coating. For example, the catalyst ink is coated on a substrate, and the coated catalyst ink is heated to dry-remove the solvent. Examples of the substrate include polytetrafluoroethylene (PTFE), an electrolyte membrane having an ion exchange group, a gas diffusion layer (GDL) composed of carbon fibers or metal fibers, and a gas diffusion layer composed of carbon fibers or metal fibers having a microporous layer (MPL). The coating method may be any method capable of uniformly coating the catalyst ink on the substrate, and examples include the die coating method, spin coating method, screen printing method, doctor blade method, squeegee method, spray coating method, and applicator method. The heating rate and heating time can be appropriately set according to the type of solvent and the like. Also, the removal rate may be increased by degassing simultaneously with heating. It is also possible to change the coating film thickness and the metal particle content. The coating film thickness may be 5 to 30 μm, and it may be coated so as to satisfy a platinum amount of 0.1 to 0.6 mg cm -2

[0044] 2. Air electrode In the present disclosure, there is provided an air electrode for a fuel cell or a metal-air battery, which contains the catalyst. The air electrode of the present disclosure contains the catalyst of the present disclosure. The air electrode of the present disclosure may be the catalyst layer of the present disclosure. The air electrode of the present disclosure may be for a fuel cell or a metal-air battery.

[0045] 3. Fuel cell In the present disclosure, there is provided a fuel cell having the air electrode as a cathode.

[0046] The fuel cell of the present disclosure has the air electrode of the present disclosure as a cathode (cathode catalyst layer). The fuel cell of the present disclosure can appropriately adopt the configuration of a conventionally known fuel cell except having the air electrode of the present disclosure as a cathode. The fuel cell of the present disclosure may have an anode containing the catalyst of the present disclosure. The fuel cell of the present disclosure may have the catalyst layer of the present disclosure as an anode (anode catalyst layer). Since the fuel cell of the present disclosure uses, as a cathode, an air electrode containing the catalyst of the present disclosure with few cracks, the power generation performance and durability performance of the fuel cell can be improved.

[0047] 4. Metal-air battery In the present disclosure, there is provided a metal-air battery having the air electrode as a cathode.

[0048] ​ The metal-air battery of the present disclosure has the air electrode of the present disclosure as the cathode. The metal-air battery of the present disclosure can appropriately adopt the configuration of a conventionally known metal-air battery except that it has the air electrode of the present disclosure as the cathode. Since the metal-air battery of the present disclosure uses an air electrode containing the catalyst of the present disclosure with few cracks as the cathode, the power generation performance and durability performance of the metal-air battery can be improved.

Example

[0049] (Example 1) Platinum cobalt alloy particles (metal particle diameter 3 - 4 nm) as metal particles, 1,3,5-triazine-2,4,6-triamine (melamine, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as an additive, carbon (acetylene black) as a carrier, and a perfluorocarbon sulfonic acid polymer as a binder were prepared, and a layer (catalyst layer) composed of a catalyst containing these was formed by the following method.

[0050] [Method for forming catalyst layer] A predetermined amount of a carrier supporting metal particles (metal particle-supported carrier, metal loading ratio 48 wt%), a binder, an additive, water and diacetone alcohol as solvents were put into a container, and these were stirred at 300 rpm for a total of 4 hours using a bead mill to prepare a catalyst ink. The catalyst ink was subjected to vacuum degassing treatment and allowed to stand for 1 day. Thereafter, the catalyst ink was again subjected to vacuum degassing treatment. The prepared catalyst ink was coated onto polytetrafluoroethylene (PTFE) as a substrate using a die coating method, and the coated catalyst ink was heated to dry and remove the solvent to form a catalyst layer. The amount of platinum contained in the catalyst layer was coated so as to be 0.20 mg cm -2 . The formed catalyst layer was observed with a microscope at 40 times and 500 times magnification. It should be noted that it is also possible to change the magnification. The crack area ratio (%) of the catalyst layer was evaluated from the area ratio in the photographed image observed at 500 times magnification. The crack area of 2% or less was rated as ◎, the crack area of 10% or less was rated as 〇, the case where the crack area was greater than 10% was rated as △, and the case where the catalyst layer could not be formed was rated as ×. The results are shown in Table 1.

[0051] [Base point amount / Acid point amount] Ratio of the total basic functional group amount of the additive to the total acidic functional group amount of the binder (Base point amount / Acid point amount) It was calculated from the following formula. The ratio of base point amount / acid point amount, the weight ratio of the additive to the carrier weight, and the weight ratio of the binder to the carrier weight are shown in Table 1. Base point amount / acid point amount (-) = (Weight ratio of the additive to the carrier weight (-) ÷ Equivalent mass per mole of the basic functional group of the additive (g / mol)) ÷ (Weight ratio of the binder to the carrier weight (-) ÷ Equivalent mass per mole of the acidic functional group of the binder (g / mol))

[0052] (Examples 2 to 20, Comparative Examples 1 to 14) The catalyst layer was formed under the same conditions as in Example 1 except that at least one of the additive type, the weight ratio of the additive to the carrier weight, the equivalent mass per mole of the basic functional group of the additive, the weight of the binder to the carrier weight, and the equivalent mass per mole of the acidic functional group of the binder was changed as shown in Tables 1 to 9 so that the base point amount / acid point amount became the values shown in Tables 1 to 9, and the crack area ratio (%) of the catalyst layer was evaluated. In Examples 13 to 14, oleylamine was used as the additive. In Comparative Examples 6 to 14, no additive was used. The results are shown in Tables 1 to 9.

[0053]

Table 1

[0054]

Table 2

[0055]

Table 3

[0056]

Table 4

[0057]

Table 5

[0058]

Table 6

[0059]

Table 7

[0060]

Table 8

[0061]

Table 9

[0062] [Evaluation Results] As shown in Tables 1 to 9, it can be seen that in Examples 1 to 20, the crack area of the catalyst layer is smaller than that in Comparative Examples 1 to 14. From the above results, it was demonstrated that when the ratio of the basic site amount to the acidic site amount is greater than 0 and not more than 6.82, the occurrence of cracks in the catalyst layer can be suppressed in the case of containing an organic nitrogen compound.

Claims

1. comprising metal particles having oxygen reduction activity, an additive having a basic functional group, a binder having an acidic functional group, and a carrier, wherein the metal particles are supported on the carrier, the additive is at least one kind of organic nitrogen compound, the ratio (basic point amount / acid point amount) of the total basic functional group amount of the additive to the total acidic functional group amount of the binder is 0.34 or more and 6.82 or less, the metal particles are at least one selected from the group consisting of platinum particles, platinum alloy particles, and composite particles containing platinum, the weight of the additive relative to the weight of the carrier is 0.0100 or more and 0.150 or less, the weight of the binder relative to the weight of the carrier is 0.700 or more and 1.15 or less, the binder is a perfluorocarbon sulfonic acid polymer, the equivalent mass per mole of the acidic functional group of the binder is 600 g / mol or more and 1100 g / mol or less, the additive is at least one selected from the group consisting of oleylamine, melamine, and polymers of melamine, a catalyst, characterized in that the equivalent mass per mole of the basic functional group of the additive is 21.0 g / mol or more and 267 g / mol or less.

2. The catalyst according to claim 1, wherein the metal particles are platinum cobalt alloy particles.

3. The additive is melamine or a polymer of melamine, The catalyst according to claim 1, wherein the equivalent mass per mole of the basic functional group of the additive is 21.0 g / mol.

4. An air electrode for a fuel cell or a metal-air battery, comprising the catalyst according to any one of claims 1 to 3.

5. A fuel cell having the air electrode according to claim 4 as a cathode.

6. A metal-air battery having the air electrode according to claim 4 as a cathode.

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