catalyst

Abstract

To provide a catalyst that contains an organic nitrogen compound and allows for improved catalytic performance.SOLUTION: A catalyst contains a metal particle with oxygen reduction activity, an additive, and a binder. The additive is at least one organic nitrogen compound. The binder is a perfiuorocarbon sulfonic acid polymer with a hydrophobic cyclic structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to catalysts. [Background technology]

[0002] Various studies have been conducted on catalysts for electrochemical oxygen reduction. Patent Document 1 discloses a catalyst for electrochemical oxygen reduction containing platinum-containing nanoparticles 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. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 221156 Summary of the Invention [Problem to be solved by the invention]

[0004] When an organic nitrogen compound is added as an additive to a catalyst with oxygen reduction activity to improve catalytic performance, it bonds with a binder with acidic functional groups, inhibiting the binder's ability to retain water and transport protons, resulting in a decrease in cell voltage.

[0005] The present disclosure has been made in view of the above circumstances, and has as its main object to provide a catalyst that contains an organic nitrogen compound and that can improve catalytic performance. [Means for solving the problem]

[0006] In the present disclosure, there is provided a catalyst comprising metal particles having oxygen reduction activity, an additive, and a binder, the additive is at least one organic nitrogen compound; The catalyst is characterized in that the binder is a perfluorocarbon sulfonic acid polymer having a hydrophobic cyclic structure. [Effects of the Invention]

[0007] The present disclosure can provide a catalyst that includes an organic nitrogen compound and can improve catalytic performance. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a graph showing the improvement in cell voltage at 0.20 A cm −2 under low humidification (30% RH) when the weight of additive relative to the weight of metal particles in the catalysts of Examples 1 to 4 and Comparative Examples 1 to 7 is changed. [Figure 2] FIG. 2 is a graph showing the improvement in cell voltage at 0.20 A cm −2 under high humidity (80% RH) when the weight of additive relative to the weight of metal particles in the catalysts of Examples 1 to 4 and Comparative Examples 1 to 7 is changed. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described. It should be noted that matters other than those specifically mentioned in this specification that are necessary for implementing the present disclosure (for example, the general configuration and manufacturing process of the catalyst that do not characterize the present disclosure) can be understood as design matters for those skilled in the art based on prior art in the relevant field. The present disclosure can be implemented based on the contents disclosed in this specification and the common general technical knowledge in the relevant field. In this specification, the use of "to" to indicate a range of values ​​means that the values ​​before and after it are included as the lower and upper limits. Any combination of upper and lower limits in the numerical range can be adopted.

[0010] 1. Catalyst In the present disclosure, there is provided a catalyst comprising metal particles having oxygen reduction activity, an additive, and a binder, the additive is at least one organic nitrogen compound; The catalyst is characterized in that the binder is a perfluorocarbon sulfonic acid polymer having a hydrophobic cyclic structure.

[0011] The organic nitrogen compound has a basic functional group, and the binder has an acidic functional group. The two form a bond through acid-base interaction. When the organic nitrogen compound additive bonds with the binder, which has an acidic functional group, it inhibits the binder's ability to retain water and transport protons. In the present disclosure, by using a perfluorocarbon sulfonic acid polymer with a hydrophobic cyclic structure, the polymer skeleton becomes rigid and the degree of freedom of the polymer is reduced. Therefore, the probability of bonding with the organic nitrogen compound additive is reduced. This allows for improved catalytic activity and improved cell voltage regardless of low or high humidity conditions.

[0012] The catalyst of the present disclosure comprises metal particles having oxygen reduction activity, an additive, and a binder.

[0013] The additive is at least one organic nitrogen compound. As organic nitrogen compounds, the nitrogen equivalent, which represents the dry weight per mole of nitrogen, is 20 to 270 g·eq. -1 It may be a compound that satisfies 20 to 70 g·eq -1 The compound may satisfy the following conditions. 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 in the molecule (mol N / mol) The organic nitrogen compound may be a compound having an amine functional group, a compound having pyridine-type nitrogen, or a compound containing a triazine ring. The organic nitrogen compound may be a monomer represented by the following general formula (1), or a polymer containing at least a portion of the monomer:

[0014] [ka]

[0015] [In general formula (1), R1, R2, and R3 each represent 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 phosphate 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, a hydroxyl group, a hydroxyl group, a nitrile group, an amide group, an imine group, an amino group, a thiol group, a hydroxyl group, a carboxylic acid group, a phosphate 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, a hydroxyl ... and a functional group selected from the group consisting of 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 in its molecular chain at least one functional group selected from the group consisting of an aromatic ring, a heterocycle, 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.]

[0016] 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.

[0017] Examples of organic nitrogen compounds include melamine compounds (nitrogen equivalent: 21 g eq -1 ), thiocyanuric acid compound (nitrogen equivalent 59 g eq -1 ), cyanuric acid compound (nitrogen equivalent 34g·eq -1 ), oleylamine (nitrogen equivalent 267g eq -1), tetradecylamine (nitrogen equivalent 213g eq -1 ), 2,4,6-Tris[bis(methoxymethyl)amino]-1,3,5-triazine (nitrogen equivalent 65g·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 145g eq -1 ) and polymers containing 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. In addition, two or more of the above-mentioned additives may be contained. The melamine compound may be melamine, a derivative of melamine, etc. The thiocyanuric acid compound may be thiocyanuric acid, a derivative of thiocyanuric acid, etc. The cyanuric acid compound may be cyanuric acid, a derivative of cyanuric acid, etc. Examples of polymers containing a melamine compound, a thiocyanuric acid compound, or a cyanuric acid compound as a monomer include melamine resins, thiocyanuric acid resins, and cyanuric acid resins having the above-mentioned melamine compound, thiocyanuric acid compound, or cyanuric acid compound in the main chain of repeating units. Among the additives listed above, melamine (1,3,5-triazine-2,4,6-triamine) or a polymer of the melamine may be used. The polymer is more difficult to desorb after adsorption onto metal particles than the monomer, improving adsorption stability. The polymer may have a degree of polymerization in the range of 1 to 10,000.

[0018] The metal particles may be any metal having oxygen reduction activity (oxygen reduction catalytic activity), such as platinum, ruthenium, iridium, rhodium, palladium, osnium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, and yttrium, or two or more of these metals may be used. Furthermore, the metal may be an oxide, nitride, sulfide, phosphide, or the like. Among the above, the metal particles may be at least one type selected from the group consisting of platinum particles, platinum alloy particles, and composite particles containing platinum. Examples of metals other than platinum contained in platinum alloys and platinum-containing composite particles include ruthenium, iridium, rhodium, palladium, osnium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, and yttrium, and the particles may contain two or more of these metals. The element ratio of metals other than platinum in the platinum alloy is not particularly limited, and may be 0.11 to 50 atm %. The particle size (particle diameter) of the metal particles is not particularly limited and may be 1 to 100 nm.

[0019] In the present disclosure, the particle size is the average crystallite size measured by X-ray diffraction. The particle size of the particles may be determined by measuring the particle sizes of 100 to 1000 particles using an electron microscope and averaging these values ​​to obtain the average particle size. In the present disclosure, particle size was measured by the above two methods.

[0020] The catalyst of the present disclosure may contain a support (carrier) such as carbon and an oxide. The metal particles may be supported on a carrier. The method for supporting the metal particles on the carrier is not particularly limited, and any conventionally known method can be appropriately adopted. The carrier may be either a primary particle or a secondary particle. 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 loaded on the carrier is not particularly limited, and may be 1 to 50%, or may be 18 to 48%. The support may be conductive carbon, oxide, or the like. The carbon may be carbon black (acetylene black, ketjen black, furnace black, etc.), activated carbon, graphite, glassy carbon, graphite, graphene, carbon fiber, carbon nanotubes, carbon nitride, carbon sulfide, carbon phosphide, or a mixture containing at least two of these. The oxide may be titanium oxide, niobium oxide, tin oxide, tungsten oxide, molybdenum oxide, or a mixture containing at least two of these.

[0021] The binder is a perfluorocarbon sulfonic acid polymer having a hydrophobic cyclic structure. The perfluorocarbon sulfonic acid polymer having a hydrophobic cyclic structure may have a hydrophobic cyclic structure represented by the following formula (2).

[0022] [ka]

[0023] [In formula (2), Rf1 and Rf2 each represent a fluorine atom or a perfluoroalkyl group having 1 to 10 carbon atoms. The perfluoroalkyl groups constituting Rf1 and Rf2 may each have an oxygen atom in the molecular chain. Rf3 and Rf4 each represent a perfluoroalkyl group having 1 to 10 carbon atoms. The perfluoroalkyl groups constituting Rf3 and Rf4 may each have an oxygen atom in the molecular chain. n is an integer of 1 or greater.] In particular, in formula (2), Rf1, Rf2, and Rf3 are each a fluorine atom, and Rf4 may be a perfluoroalkyl group having two carbon atoms (CF2CF3).

[0024] The binder may have an acidic functional group. The binder may have, as the acidic functional group, sulfonic acid, phosphoric acid, quaternary ammonium cation, or the like. The binder may be a polymer containing a perfluorocarbon sulfonic acid polymer as a main component. Examples of polymers other than perfluorocarbon sulfonic acid polymers include anion exchange polymers, polyether ether ketones, and polybenzimidazoles.

[0025] The equivalent mass per mole of acidic functional groups of the binder may be 600 g / mol or more and less than 1100 g / mol.

[0026] [Weight of additive relative to weight of metal particles] In the catalyst of the present disclosure, the ratio of the weight of the additive to the weight of the metal particles may be 0.0100 or more and 0.150 or less. The weight of the additive relative to the weight of the metal particles is defined as (weight of the additive) / (weight of the metal particles).

[0027] [Binder weight relative to carrier weight] In the catalyst of the present disclosure, the weight ratio of the binder to the weight of the support may be 0.50 or more and 0.85 or less. The binder weight relative to the carrier weight is defined as (binder weight) / (carrier weight).

[0028] [Additive weight evaluation method] Methods for evaluating the weight of the additive contained in the catalyst of the present disclosure include a method for measuring the nitrogen content by CHN elemental analysis, and a method for extracting the additive from the catalyst and measuring the additive directly. The method of measuring nitrogen content using CHN elemental analysis involves burning a sample with oxygen for a certain period of time, then quantifying the amounts of carbon, hydrogen, and nitrogen atoms contained in the sample by quantifying the amounts of carbon dioxide, water, and nitrogen oxides produced.By comparing the amount of nitrogen in the sample before and after adding the additive, it is possible to evaluate the amount of the additive. The method of extracting additives from oxygen reduction catalysts and measuring them directly involves extracting the additives in a solvent that dissolves the additives contained in the catalyst and then qualitatively and quantitatively analyzing the additives. Analytical techniques include chromatography, ultraviolet-visible spectroscopy (UV-vis), infrared spectroscopy (IR), and nuclear magnetic resonance (NMR).

[0029] [Method for evaluating metal particle weight, carrier weight, and binder weight] Methods for evaluating the weight of the 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), high-frequency inductively coupled plasma emission spectroscopy (ICP), and the like. Thermogravimetric analysis (TG) is a method for measuring weight when the gas atmosphere, temperature, etc. are changed. After heating and burning off moisture, conductive carriers, polymers with ion exchange groups, and impurities, the remaining weight is taken as the weight of the metal particles. Inductively coupled plasma optical emission spectroscopy (ICP) is a technique for qualitatively and quantitatively determining the elements contained in a substance based on the wavelength and intensity of the emission lines emitted by atoms excited by plasma. By controlling the measurement temperature and gas atmosphere, it is possible to calculate the weight of any substance. It is possible to directly quantify the weight of metal particles, carrier, and binder contained in the catalyst.

[0030] 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 in the cathode of a fuel cell, the anode of a fuel cell, or the air electrode of a metal-air battery.

[0031] The catalyst of the present disclosure may be in the form of a layer, i.e., the catalyst of the present disclosure may be a catalyst layer. Examples of the method for forming the catalyst layer include the following methods.

[0032] [Catalyst ink preparation process] First, a predetermined amount of a carrier carrying metal particles (metal particle-carrying carrier), a binder, an additive, and a solvent is placed in a container, and these are stirred using a stirrer to prepare a catalyst ink. The type of solvent is not particularly limited, and any liquid can be used, and may be 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, and propylene glycol. Examples of the stirrer include an ultrasonic homogenizer, a jet mill, a ball mill such as a bead mill, a high shear mill, a film mix, etc. The stirring conditions such as the stirring speed, stirring time, and rotation speed are not particularly limited and can be set appropriately. Thereafter, a vacuum degassing treatment may be carried out. There is no limit to the time for leaving the mixture to stand, and it may be left to stand for one day. It is also possible to use the mixture without leaving it to stand. Alternatively, the vacuum degassing treatment may be carried out again.

[0033] [Catalyst ink coating process] The prepared catalyst ink is coated onto a substrate, and the solvent is then removed after coating. For example, the catalyst ink is coated onto a substrate such as polytetrafluoroethylene (PTFE), and the coated catalyst ink is heated to dry and remove the solvent. The coating method may be any method that can uniformly coat the catalyst ink on the substrate, and examples thereof include die coating, spin coating, screen printing, doctor blade, squeegee, spray coating, and applicator methods. The heating rate and heating time can be appropriately set depending on the type of solvent, etc. The removal rate may also be increased by degassing simultaneously with heating. The coating thickness and the metal particle content can be changed. The coating thickness may be 5 to 30 μm, and the platinum content may be 0.1 to 0.6 mg cm -2 The coating may be carried out so as to satisfy the above.

[0034] 2. Air electrode The present disclosure provides an air electrode for a fuel cell or a metal-air battery, which includes the catalyst. The cathode of the present disclosure includes the catalyst of the present disclosure. The cathode of the present disclosure may also include the catalyst layer of the present disclosure. The cathode of the present disclosure may be for use in a fuel cell or a metal-air battery.

[0035] 3.Fuel cell The present disclosure provides a fuel cell having the air electrode as a cathode.

[0036] The fuel cell of the present disclosure has the air electrode of the present disclosure as the cathode (cathode catalyst layer). The fuel cell of the present disclosure can appropriately adopt the configuration of a conventionally known fuel cell, except that it has 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). The fuel cell of the present disclosure uses an air electrode containing the catalyst of the present disclosure as a cathode, and therefore the power generation performance of the fuel cell can be improved.

[0037] 4. Metal-air battery The present disclosure provides a metal-air battery having the air electrode as a cathode.

[0038] The metal-air battery of the present disclosure has the air electrode of the present disclosure as a 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. The metal-air battery of the present disclosure uses an air electrode containing the catalyst of the present disclosure as a cathode, and therefore the power generation performance of the metal-air battery can be improved. [Example]

[0039] Example 1 Platinum-cobalt alloy particles (metal particle diameter 3 to 4 nm) were prepared as metal particles, 1,3,5-triazine-2,4,6-triamine (melamine, Fujifilm Wako Pure Chemical Industries, Ltd.) was prepared as an additive, carbon (acetylene black) was prepared as a carrier, and a perfluorocarbon sulfonic acid polymer with a hydrophobic cyclic structure was prepared as a binder. A layer (catalyst layer) consisting of a catalyst containing these was formed by the following method. The perfluorocarbon sulfonic acid polymer having a hydrophobic cyclic structure used as a binder was synthesized using the method described in Example 1 of JP 2013-216811 A. The hydrophobic cyclic structure of the synthesized binder is represented by the above formula (2), in which Rf1, Rf2, and Rf3 are each a fluorine atom, and Rf4 is a perfluoroalkyl group having two carbon atoms (CFCF). The equivalent mass per mole of acidic functional group of the binder was 600 g / mol. The ratio of the binder weight to the carrier weight in the catalyst was 0.85. The ratio of the weight of the additive to the weight of the metal particles in the catalyst was set to 0.0100.

[0040] [Catalyst layer formation method] A predetermined amount of a carrier carrying metal particles (metal particle-carrying carrier, metal loading ratio 48 wt%), a binder, an additive, and water and diacetone alcohol as solvents were placed in a container, and these were stirred at 300 rpm using a bead mill for a total of 4 hours to prepare a catalyst ink. The catalyst ink was subjected to vacuum degassing treatment and left to stand for one day. Thereafter, the catalyst ink was again subjected to vacuum degassing treatment. The prepared catalyst ink was applied to a polytetrafluoroethylene (PTFE) substrate using a die coating method, and the applied catalyst ink was heated to dry and remove the solvent, forming a catalyst layer. The platinum content in the catalyst layer was 0.20 mg cm. -2 The coating was applied so that

[0041] Examples 2 to 4 A layer made of catalyst (catalyst layer) was formed under the same conditions as in Example 1, except that the weight of additives relative to the weight of metal particles in the catalyst was changed as shown in Table 1.

[0042] (Comparative Examples 1 to 5) A perfluorocarbon sulfonic acid polymer (DE2020 manufactured by Chemours) without a hydrophobic cyclic structure was prepared as a binder, and a layer made of a catalyst (catalyst layer) was formed under the same conditions as in Example 1, except that the weight of additives relative to the weight of metal particles in the catalyst was changed as shown in Table 1. The equivalent mass per mole of acidic functional groups of the binder was 1100 g / mol.

[0043] (Comparative Example 6) A layer made of a catalyst (catalyst layer) was formed under the same conditions as in Example 1, except that no additive was used and a perfluorocarbon sulfonic acid polymer (DE2020 manufactured by Chemours) without a hydrophobic cyclic structure was used as the binder. Note that, since no additive was used, the weight of the additive relative to the weight of the metal particles in Comparative Example 6 is 0.

[0044] (Comparative Example 7) Except for not using an additive, a layer made of a catalyst (catalyst layer) was formed under the same conditions as in Example 1. Since no additive was used, the weight of the additive relative to the weight of the metal particles in Comparative Example 7 was 0.

[0045] [Method for producing membrane-electrode gas diffusion layer assembly] Each of the catalyst layers produced in Examples 1 to 4 and Comparative Examples 1 to 7 was prepared as a cathode catalyst layer, an electrolyte membrane (Nafion NR211) was prepared, and an anode catalyst layer containing TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Kogyo was prepared as an anode catalyst. The electrolyte membrane was sandwiched between the cathode catalyst layer and the anode catalyst layer, and a temperature (130°C) and pressure (3 MPa) were applied to thermocompress the cathode catalyst layer, the electrolyte membrane, and the anode catalyst layer to form a membrane-electrode assembly. Any electrolyte membrane can be used, and the temperature and pressure during thermocompression bonding can be set as appropriate. Two gas diffusion layers (GDL 22BB manufactured by SGL) made of carbon fiber were prepared and placed on both sides of the membrane-electrode assembly to produce the membrane-electrode gas diffusion layer assemblies of Examples 1 to 4 and Comparative Examples 1 to 7. Any gas diffusion layer can be used.

[0046] [Actual 1cm 2 Cell Evaluation] The electrode part is 1cm 2 Using each membrane-electrode gas diffusion layer assembly, cell evaluation was carried out. The current-voltage characteristics were evaluated under low humidity conditions (30% RH) and high humidity conditions (80% RH). The current-voltage characteristics were obtained at a sweep rate of 20 mA / s using an anodic sweep. The cell temperature was 80°C, the pressure was 150 kPa_ABS, the cathode gas was air, and the cathode gas flow rate was 2.0 L / min. It is possible to obtain current-voltage data under any desired conditions. From the evaluation results of the current-voltage characteristics, the cell voltage improvement (mV) compared to the case without additives was calculated under low humidity conditions (30% RH) and high humidity conditions (80% RH). These results are shown in Tables 1 to 3. The criteria for judging the cell voltage improvement were as follows: if the cell voltage improvement was greater than 10.0 mV, it was marked with a double circle; if it was 5.0 mV or more but less than 10.0 mV, it was marked with a circle; if it was 1.0 mV or more but less than 5.0 mV, it was marked with a triangle; and if it was less than 1.0 mV, it was marked with an x.

[0047] [Table 1]

[0048] [Table 2]

[0049] [Table 3]

[0050] [Evaluation results] FIG. 1 shows the relationship between the additive weight relative to the metal particle weight in the catalysts of Examples 1 to 4 and Comparative Examples 1 to 7 and the 0.20 A cm at low humidity (30% RH). -2 10 is a graph showing an increase in cell voltage in the FIG. 2 shows the relationship between the additive weight relative to the metal particle weight in the catalysts of Examples 1 to 4 and Comparative Examples 1 to 7 and the 0.20 A cm at high humidity (80% RH). -2 10 is a graph showing an increase in cell voltage in the As shown in Figures 1 and 2 and Tables 1 to 3, the cells using the catalysts of Examples 1 to 4 have a larger improvement in cell voltage than the cells using the corresponding catalysts of Comparative Examples 1 to 4 under both low humidification conditions (30% RH) and high humidification conditions (80% RH) when compared to the cells without additives. The above results demonstrate that by using a perfluorocarbon sulfonic acid polymer with a hydrophobic cyclic structure as a binder for a catalyst containing an organic nitrogen compound, catalytic activity can be improved regardless of whether the catalyst is under low or high humidity conditions, and cell voltage can also be improved.

Claims

1. A catalyst for electrochemical oxygen reduction, comprising: The catalyst comprises metal particles having oxygen reduction activity, an additive, a binder, and a support; the metal particles are supported on the support, the additive is at least one organic nitrogen compound; the binder is a perfluorocarbon sulfonic acid polymer having a hydrophobic cyclic structure, the organic nitrogen compound is melamine (1,3,5-triazine-2,4,6-triamine) or a polymer of the melamine; the metal particles are at least one selected from the group consisting of platinum particles, platinum alloy particles, and platinum-containing composite particles; the support is electrically conductive carbon, A catalyst characterized in that the weight ratio of the additive to the weight of the metal particles is 0.0100 or more and 0.150 or less.

2. 2. The catalyst of claim 1, wherein the organic nitrogen compound is melamine.

3. 2. The catalyst of claim 1, wherein the weight of said binder relative to the weight of said support is 0.85.

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