WO2012160957A1 - Electrode catalyst and method for producing same - Google Patents

Electrode catalyst and method for producing same Download PDF

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Publication number
WO2012160957A1
WO2012160957A1 PCT/JP2012/061722 JP2012061722W WO2012160957A1 WO 2012160957 A1 WO2012160957 A1 WO 2012160957A1 JP 2012061722 W JP2012061722 W JP 2012061722W WO 2012160957 A1 WO2012160957 A1 WO 2012160957A1
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Prior art keywords
electrode
catalyst
polymer
metal
diaminopyridine
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PCT/JP2012/061722
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French (fr)
Japanese (ja)
Inventor
橋本　和仁
一哉 渡邉
勇 趙
和秀 神谷
周次 中西
理生 鈴鹿
亮 釜井
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国立大学法人東京大学
パナソニック株式会社
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Publication of WO2012160957A1 publication Critical patent/WO2012160957A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/16—Biochemical fuel cells, i.e. cells in which microorganisms function as catalysts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88—Processes of manufacture
    • H01M4/8878—Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body
    • H01M4/8882—Heat treatment, e.g. drying, baking
    • H01M4/8885—Sintering or firing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/9041—Metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/9091—Unsupported catalytic particles; loose particulate catalytic materials, e.g. in fluidised state
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M2008/1095—Fuel cells with polymeric electrolytes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to an electrode catalyst and a production method thereof, a gas diffusion electrode containing the catalyst, and a fuel cell using the same.
  • Fuel cells are attracting attention as a new energy system that replaces conventional fossil fuels.
  • Fuel cells include hydrogen as an electron donor, such as polymer electrolyte fuel cells (hereinafter referred to as “PEFC”) and phosphoric acid fuel cells (hereinafter referred to as “PAFC”).
  • PEFC polymer electrolyte fuel cells
  • PAFC phosphoric acid fuel cells
  • MFC microbial fuel cell
  • An electrode catalyst is included in the cathode (air electrode), and hydrogen gas and / or oxygen gas is ionized by the catalytic action.
  • a platinum catalyst such as platinum (Pt) or a platinum alloy is generally known, and the catalyst component supported on a carbon carrier (platinum-supported carbon) is gas diffused. Widely used as an electrode (electrode for fuel cell).
  • Pt is an expensive and rare metal, it not only hinders the spread of fuel cells to consumer use, but also has a problem with the amount of resources that can be used for future mass production. is there.
  • Patent Documents 1 and 2 and Non-Patent Documents 1 and 2 disclose electrode catalysts based on metal complexes composed of a polymer and a catalyst metal as Pt substitute catalysts.
  • a catalyst component and an indole, isoindole, naphthopyrrole, pyrrolopyridine, benzimidazole, purine, carbazole, phenoxazine, and phenothiazine are selected as an electrocatalyst having a high catalytic activity and a long life.
  • An electrode catalyst comprising a non-platinum type conductive polymer metal complex comprising a conductive polymer having at least one repeating unit structure and a metal ion, and a gas diffusion electrode using the same are disclosed.
  • Patent Document 2 it has a high specific surface area, contains two or more chemical structures selected from —NH 2 , ⁇ NH, and ⁇ N— in the molecule, and has a planar structure and a metal.
  • a fuel cell catalyst obtained by heat-treating a coordination polymer metal complex having a porous skeleton structure is disclosed.
  • Non-Patent Document 1 discloses an invention in which an iron (II) phthalocyanine (FePc) and cobalt-tetramethoxyphenylporphyrin (Cobalt ⁇ ⁇ TetraMethoxyPhenylPorphyrin, hereinafter referred to as “CoTMPP”)-based oxygen reduction catalyst is used as an MFC cathode.
  • an iron (II) phthalocyanine (FePc) and cobalt-tetramethoxyphenylporphyrin (Cobalt ⁇ ⁇ TetraMethoxyPhenylPorphyrin, hereinafter referred to as “CoTMPP”)-based oxygen reduction catalyst is used as an MFC cathode.
  • Non-Patent Document 2 the performance of proton-conducting ion exchange membranes can be achieved by using Co-polypyrrole doped with 4-toluenesulfonic acid (Cobalt PolyPyrrole; hereinafter referred to as “CoPPy”) as a platinum substitute catalyst for the cathode of PEFC.
  • CoPPy Co-polypyrrole doped with 4-toluenesulfonic acid
  • Non-patent Document 2 In metal complexes, metal atoms are generally more easily coordinated with nitrogen atoms (N), and the greater the number of N atoms that can function as a ligand in the polymer, the more the catalyst activity improves. Attempts have been made to increase (Non-patent Document 2). However, in the metal complex of the above prior art, it cannot be said that the number of N atoms serving as a ligand in the polymer is necessarily large due to the structure of the monomer constituting the polymer.
  • the present invention has an oxygen reduction reaction (Oxygen Reduction Reaction; hereinafter referred to as “ORR”) catalytic activity, durability and corrosion resistance equivalent to or higher than that of a Pt-based catalyst, and is inexpensive and stable. It is an object of the present invention to provide an electrocatalyst that can be supplied automatically, a gas diffusion electrode using the electrode catalyst, and a fuel cell having the energy conversion efficiency, long life, and low cost provided with the electrode.
  • ORR oxygen reduction reaction
  • the present inventors have developed a new electrode catalyst in order to solve the above problems.
  • an electrode using a metal complex composed of a diaminopyridine polymer and a catalyst metal as a catalyst component has higher energy conversion efficiency than a Pt electrode and can generate a high output current.
  • the diaminopyridine polymer has a larger number of nitrogen atoms that can serve as a ligand than the conventional polymer metal complex, and it is considered that a larger number of catalyst metals can be coordinated to bring about the above effect.
  • the invention is based on the findings, and specifically provides the following inventions.
  • the manufacturing method of the electrode catalyst including the 3rd process of obtaining a complex.
  • the molar ratio of 1 or 2 or more selected from the group consisting of diaminopyridine, diaminopyridine derivative, triaminopyridine, triaminopyridine derivative, tetraaminopyridine and tetraaminopyridine derivative to the catalytic metal atom is 3:
  • a gas diffusion electrode comprising a conductive carrier carrying the electrode catalyst according to any one of (1) to (7) and (15).
  • a fuel cell comprising the gas diffusion electrode according to any one of (16) to (18).
  • the electrocatalyst of the present invention can provide an inexpensive electrocatalyst having an ORR catalytic activity, durability and corrosion resistance equivalent to or higher than that of the current mainstream Pt-based catalyst.
  • an electrocatalyst having an ORR catalyst activity, durability, and corrosion resistance equivalent to or higher than that of a conventional electrocatalyst can be produced at a low cost.
  • the gas diffusion electrode of the present invention it is possible to provide a gas diffusion electrode that has high catalytic activity, durability and corrosion resistance, and can be stably supplied at low cost.
  • the fuel cell of the present invention it is possible to provide a fuel cell with high energy conversion efficiency, long life and low cost.
  • each electrode catalyst obtained by calcining a polymer metal complex composed of 2,6-diaminopyridine polymer and cobalt nitrate mixed at different mixing ratios is shown. It is a figure which shows the comparison of ORR catalyst activity by RRDE (rotating ring disk electrode) provided with the electrode catalyst.
  • RRDE contains CoDAPP (Co-2,6-diaminopyridine polymer), CoTMPP, CoPPy and Pt electrocatalysts.
  • A shows a CoDAPP catalyst
  • (b) shows a CoTMPP catalyst
  • (c) shows a CoPPy catalyst
  • (d) shows a Pt catalyst.
  • a gas diffusion electrode (CoDAPP electrode) containing a CoDAPP catalyst (b) a gas diffusion electrode (CoTMPP electrode) containing a CoTMPP catalyst, and (c) a gas diffusion electrode (CoPPy electrode) containing a CoPPy catalyst.
  • D show gas diffusion electrodes (Pt electrodes) each containing a Pt catalyst. The power density of MFC when each gas diffusion electrode is used as a cathode is shown.
  • the polarization curves of each gas diffusion electrode measured using an Ag / AgCl electrode as a reference electrode are shown in (a) and (a ′), respectively, when the CoDAPP electrode is used as the cathode, ) And (b ′) show the performance of the anode and the cathode, respectively, when the CoTMPP electrode is used as the cathode, and (c) and (c ′) show the performance of the anode and the cathode, respectively, when the CoPPy electrode is used as the cathode. (D) and (d ′) show the performance of the anode and the cathode, respectively, when the Pt electrode is used as the cathode.
  • FIG. 6 is a polarization curve diagram showing a comparison of ORR catalytic activity at pH 7 of RRDE equipped with electrocatalysts having different catalytic metals.
  • A shows the CoDAPP catalyst
  • (b) shows the FeDAPP catalyst
  • (c) shows the Fe / CoDAPP catalyst.
  • (A) shows the CoDAPP catalyst
  • (b) shows the FeDAPP catalyst
  • (c) shows the Fe / CoDAPP catalyst.
  • Electrode catalyst 1-1 Outline
  • summary The 1st Embodiment of this invention is an electrode catalyst.
  • the electrode catalyst of the present invention is characterized by having a specific metal complex as a catalyst component and having the same or higher ORR catalyst activity, durability and corrosion resistance as compared with conventional electrode catalysts such as Pt-based catalysts.
  • the electrode catalyst of the present invention contains, as a catalyst component, 1) a metal complex having specific physical properties, or 2) a metal complex formed by firing a specific polymer metal complex.
  • the configuration of the electrode catalyst of the present invention will be specifically described below.
  • the “metal complex” refers to a compound comprising a polymer and / or a modified product thereof and a catalytic metal, wherein a ligand in the polymer or the modified product is coordinated with the catalytic metal.
  • fired metal complex refers to a compound obtained by firing a polymer metal complex.
  • “Baking (treatment)” here refers to a heat treatment at a high temperature.
  • the “polymer metal complex” refers to the metal complex in a state where no baking treatment is performed.
  • the fired metal complex and the polymer metal complex are comprehensively referred to regardless of whether or not the firing treatment has been completed.
  • the essential component functioning as a catalyst component is, as will be described later, a specific polymer and / or a modified product thereof, and a metal complex composed of a catalytic metal, or a specific polymer and a catalyst.
  • these metal complexes that are essential components in the electrode catalyst of the present invention are collectively referred to as “2-4 aminopyridine polymer metal complexes”.
  • 2-4 aminopyridine polymer means a monomer diaminopyridine (C 5 H 7 N 3 ), diaminopyridine derivative, triaminopyridine (C 5 H 8 N 4 ), triaminopyridine derivative, It is a general name for compounds in which one or more selected from the group consisting of tetraaminopyridine (C 5 H 9 N 5 ) and tetraaminopyridine derivatives are polymerized.
  • the term “polymer” means “2-4 aminopyridine polymer” unless otherwise specified.
  • the “modified product” is a modified product of the polymer, and refers to a compound, an oligomer, and the like generated by thermal decomposition of the polymer when the polymer metal complex is baked.
  • the diaminopyridine, triaminopyridine and tetraaminopyridine are compounds in which the hydrogen atom (H) of pyridine (C 5 H 5 N) is substituted with 2 , 3 and 4 amino groups (—NH 2 ), respectively.
  • the monomer constituting the 2-4 aminopyridine polymer may be composed of only one kind or a combination of two or more kinds.
  • Diaminopyridine has positional isomers of 2, 3-diaminopyridine, 2, 4-diaminopyridine, 2, 5-diaminopyridine, 2, 6-diaminopyridine and 3, 4-diaminopyridine, and triaminopyridine has 2, 3, 4-triaminopyridine, 2, 3, 5-triaminopyridine, 2, 3, 6-triaminopyridine, 2, 4, 5-triaminopyridine, 2, 4, 6-triaminopyridine And 3, 4, 5-triaminopyridine, and tetraaminopyridine includes 2, 3, 4, 5-tetraaminopyridine, 2, 4, 5, 6-tetraaminopyridine and 2, 3 , 5, 6-tetraaminopyridine positional isomers are known, but each monomer constituting the 2-4 aminopyridine polymer may be any positional isomer. Moreover, it may be composed only of the same positional isomers, or may be composed of two or more different positional isomers.
  • examples of the derivatives of diaminopyridine include 4 methyl-2, 6-diaminopyridine, 4 ethyl-2, 6-diaminopyridine and 3methyl-2, 6-diaminopyridine.
  • Examples of the derivative of triaminopyridine include 3methyl-2, 3, 6-triaminopyridine and 3ethyl-2, 3, 6-triaminopyridine.
  • Tetraaminopyridine derivatives include, for example, 4N methylamino-2, 3, 6-triaminopyridine, 4N methylamino-2, 4, 6-triaminopyridine and 4N, N diamino-2, 3, 6-triaminopyridine. Aminopyridine is mentioned.
  • the arrangement of the respective monomers and / or positional isomers in the 2-4 aminopyridine polymer is a polymerization.
  • it may be polymerized so that a combination of specific monomers is regularly repeated, or may be polymerized randomly.
  • the ligand included in the 2-4 aminopyridine polymer coordinates the catalyst metal.
  • the atom (coordinating atom) that can be a ligand in the polymer include a nitrogen atom of a pyridine ring and / or a nitrogen atom of an amino group.
  • diaminopyridine and derivatives thereof, triaminopyridine and derivatives thereof, and tetraaminopyridine and derivatives thereof include three, four, and five nitrogen atoms, respectively, that can be ligands. . Therefore, the 2-4 aminopyridine polymer composed of these monomers has a high nitrogen atom content.
  • the electrocatalyst of the present invention can have high ORR catalytic activity.
  • diaminopyridine polymer in which only diaminopyridine is polymerized can be mentioned.
  • the positional isomer constituting the diaminopyridine polymer is not limited, but 2,6-diaminopyridine and / or 2,3-diaminopyridine are preferable. These positional isomers are because the nitrogen atoms (N) are arranged closest to each other in the molecule, so that the catalytic metal can be coordinated more stably in the polymer.
  • a more preferred diaminopyridine polymer is a 2,6-diaminopyridine polymer in which only 2,6-diaminopyridine monomer is polymerized.
  • the chemical polymerization reaction for linking the monomers constituting the 2-4 aminopyridine polymer is not limited, but is preferably anionic polymerization.
  • the polymer is a 2,6-diaminopyridine polymer
  • the polymer contains, for example, a chemical structure represented by the following formula (I) and / or (II) by anionic polymerization of 2,6-diaminopyridine. Is expected.
  • the “catalytic metal” is a metal atom or metal ion coordinated in a metal complex.
  • the catalyst metal is not particularly limited, but is preferably a transition metal. Specifically, for example, titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr ), Niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re ), Osnium (Os), iridium (Ir), Pt, gold (Au), and the like or ions thereof.
  • the catalyst metal is preferably Cr, Mn, Fe, Co, Ni, and Cu.
  • the metal complex may coordinate one type of catalyst metal, or may coordinate two or more different catalyst metals.
  • An example is a metal complex in which Fe and Co are coordinated.
  • Pt and Au are rare and expensive, it seems to be contrary to the purpose of the present invention, but by using them coordinated in a metal complex, the amount of Pt used compared to known Pt-based catalysts Therefore, the object of the present invention can be achieved. Therefore, it can be included in the catalyst metal in the present invention.
  • a 2,6-diaminopyridine polymer is a metal complex in which cobalt is coordinated as a catalytic metal (Co-2,6-diaminopyridine polymer; Co-2,6-diaminopyridine polymer,
  • it is expected to include, for example, a structure represented by the following formula (III) in the case of “CoDAPP”.
  • Me represents a catalyst metal (Co in this example).
  • the 2-4 aminopyridine polymer metal complex of the present invention is preferably obtained by baking a polymer metal complex. This is because the catalyst metal in the polymer metal complex is stably coordinated to the nitrogen atom by the calcination treatment, and as a result, stable catalytic activity, high durability, and corrosion resistance can be obtained by chemical curing.
  • the mixing ratio of the 2-4 aminopyridine polymer to the catalyst metal salt in the 2-4 aminopyridine polymer metal complex is 3: 1 to 5: 1, preferably 3.5: 1 to 4.5, as the molar ratio of the raw material monomer to the catalyst metal atom. : Select to be 1. Even when two or more different catalyst metals are used, the molar ratio of the raw material monomers to the total catalyst metal atoms may be within the above range.
  • the molar ratio between different catalytic metals is not particularly limited. What is necessary is just to determine suitably according to the kind etc. of the catalyst metal to be used. For example, when using Co and Fe, the molar ratio of Co and Fe may be selected within a range of 1: 0.1 to 1:10.
  • the “calcination temperature” for the calcination treatment is 650 to 800 ° C., preferably 680 to 780 ° C., more preferably 690 to 760 ° C., further preferably 700 to 750 ° C.
  • the firing treatment can be performed by a known method for heat-treating the electrode catalyst.
  • the dried polymer metal complex powder may be calcined at a calcining temperature for 30 minutes to 5 hours, preferably 1 hour to 2 hours in a reducing gas atmosphere or an inert gas atmosphere.
  • the firing is performed in a reducing gas atmosphere.
  • ammonia can be used as the reducing gas.
  • the inert gas for example, nitrogen can be used.
  • nitrogen doping is generally not performed only by firing the carbon material in an inert gas atmosphere.
  • the object can be achieved even by firing in an inert gas atmosphere.
  • it may be further fired in a reducing gas atmosphere.
  • the “specific physical properties” are physical properties exhibited by the 2-4 aminopyridine polymer metal complex in the present invention.
  • the catalyst metal nitrogen in the polymer metal complex A property that satisfies at least one of the following (i) to (iii) obtained as a result of stabilization of coordination to an atom.
  • Element ratio of nitrogen (N) / carbon (C) is 0.11 or more in molar ratio
  • Element ratio of catalyst metal (Metal) / nitrogen (N) is 0.03 or more in molar ratio, preferably (Iii)
  • the content of the catalyst metal coordinated to the nitrogen atom is 0.05 or more and 0.4 mol% or more, and the content of the nitrogen atom is 6.0 mol% or more.
  • Each content of the catalyst metal coordinated to carbon, nitrogen, and nitrogen atom in the electrode catalyst is measured by X-ray photoelectron spectroscopy. All the content rates are their ratios when the metal complex is used as a reference (when the metal complex is 100 mol%).
  • Calcination may cause a part of the 2-4 aminopyridine polymer to be modified, and the polymer form may be lost.
  • Such modification is permissible as long as the calcined metal complex can be used as an electrocatalyst, and therefore the 2-4 aminopyridine polymer metal complex constituting the electrocatalyst of the present invention is calcined with 2-4 aminopyridine polymer. May contain a modified material.
  • the shape of the fired metal complex is not particularly limited. However, it is preferable that the specific surface area per unit area of the electrode catalyst supported on the electrode surface is large. This is because the catalytic activity (mass activity) per unit mass of the electrode can be further increased. Therefore, a preferable shape is a particle shape, particularly a powder shape.
  • the specific surface area of the calcined metal complex is preferably 500 m 2 / g or more, more preferably 550 m 2 / g or more. Such a specific surface area can be measured by a nitrogen BET adsorption method or the like.
  • the conductivity of the electrode catalyst is preferably in the range of 0.1 s / cm to 10 s / cm.
  • the electrode catalyst of the present invention can contain a catalyst component other than the calcined metal complex.
  • a catalyst component other than the calcined metal complex.
  • a known catalyst such as a CoTMPP catalyst may be included.
  • the 2nd Embodiment of this invention is a manufacturing method of an electrode catalyst. This manufacturing method can manufacture the electrode catalyst as described in the first embodiment at a low cost.
  • the production method of the present invention includes (a) a polymerization step, (b) a polymer metal complex formation step, and (c) a firing step.
  • a polymerization step includes (a) a polymerization step, (b) a polymer metal complex formation step, and (c) a firing step.
  • the “polymerization step” is a step of synthesizing a 2-4 aminopyridine polymer by anionic polymerization of diaminopyridine, triaminopyridine and / or tetraaminopyridine.
  • the monomer to be polymerized only one kind may be used, or two or three kinds may be combined.
  • the mixing molar ratio of each monomer there is no particular limitation on the mixing molar ratio of each monomer.
  • Those skilled in the art may appropriately determine the catalytic activity.
  • An example of a preferred monomer used in the polymerization step is the case of diaminopyridine alone.
  • the positional isomer of each monomer used for polymerization is not particularly limited, but preferably a positional isomer in which a nitrogen atom serving as a ligand in the monomer molecule is located proximally.
  • a positional isomer in which a nitrogen atom serving as a ligand in the monomer molecule is located proximally is preferable.
  • the monomer is polymerized by an anionic polymerization reaction.
  • the anionic polymerization reaction may be performed using a known method commonly used in the art. For example, a strong base solution is allowed to act on the monomer to deprotonate it, and each monomer is polymerized using the generated carbanion as a nucleophile.
  • a strong base solution is allowed to act on the monomer to deprotonate it, and each monomer is polymerized using the generated carbanion as a nucleophile.
  • the base used in the strong base solution for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide and the like can be used.
  • the polymerization temperature and polymerization time are not particularly limited as long as the reaction proceeds. Usually, this step can be achieved by reacting at a temperature of 5 to 40 ° C. for about 5 to 48 hours.
  • the recovered 2-4 aminopyridine polymer is preferably washed with water (including deionized water and distilled water) and then dried and used in the subsequent steps.
  • the following polymer metal complex formation step can be started without passing through this step.
  • Polymer metal complex formation step refers to the formation of a polymer metal complex by coordinating a catalyst metal to the polymer by mixing a 2-4 aminopyridine polymer and a catalyst metal salt. It is a process. The nitrogen atom contained in the 2-4 aminopyridine polymer becomes a ligand (coordinating atom) and coordinates with the catalytic metal to form a polymer metal complex.
  • Catalytic metal salt is a salt of a catalytic metal to be coordinated in a metal complex, and specifically includes a catalytic metal hydrochloride, sulfate, nitrate, phosphate, acetate, and the like.
  • the catalyst metal in this step is not particularly limited as long as it is a metal having catalytic activity in the electrode catalyst, but is preferably a transition metal. Specifically, for example, the transition metals described in the first embodiment can be mentioned.
  • salts of Cr, Mn, Fe, Co, Ni and Cu are suitable as the catalyst metal salt in this step, and a catalyst metal salt of Fe or Co is particularly preferable. Specific examples include iron chloride, iron nitrate, iron sulfide, cobalt nitrate, cobalt chloride, and cobalt sulfide.
  • the mixing ratio of the 2-4 aminopyridine polymer and the catalytic metal salt may be selected so that the molar ratio of the raw material monomer to the catalytic metal atom is 3: 1 to 5: 1, preferably 3.5: 1 to 4.5: 1. . That is, the mass of the polymer and the catalyst metal salt is selected so that (the number of moles of the repeating unit constituting the polymer) :( the number of moles of the metal contained in the catalyst metal salt) is within the above preferable range. What is necessary is just to mix a metal salt.
  • the catalyst metal or its ion can be coordinated in the 2-4 aminopyridine polymer by mixing and suspending these in a suitable solvent and further stirring sufficiently.
  • water, ethanol, propanol or a mixed solution thereof for example, water and ethanol or a mixed solution of water and (iso) propanol can be used.
  • the mixing temperature and mixing time are not particularly limited as long as the reaction proceeds. Usually, this reaction can be achieved by reaction at a temperature of 50 to 70 ° C. for about 30 minutes to 5 hours. Ultrasonic mixing may be performed in order to sufficiently mix the two substances.
  • the formed polymer metal complex precipitates as a solid in the solvent.
  • the solvent is removed by centrifugation, filtration or evaporation, and the target polymer metal complex is recovered.
  • the target polymer metal complex In order to remove uncoordinated catalyst metal, etc., it may be washed with water (including deionized water and distilled water).
  • the recovered polymer metal complex may be pulverized as necessary using, for example, a quartz mortar.
  • the “firing step” refers to firing the polymer metal complex obtained in the polymer metal complex forming step at a high temperature in a reducing gas atmosphere or an inert gas atmosphere. It is a process to obtain. By this step, the catalyst metal moves in the polymer metal complex, whereby a highly durable electrode active component in which the catalyst metal is stably coordinated is prepared.
  • Calcination temperature is 650 to 800 ° C, preferably 680 to 780 ° C, more preferably 690 to 760 ° C, and further preferably 700 to 750 ° C. By calcining at this temperature, a calcined metal complex as a catalyst component having high ORR catalyst activity and durability can be obtained.
  • ammonia gas can be used as the reducing gas.
  • the calcination treatment can be performed by a known method for heat-treating the electrode catalyst.
  • the powder of the polymer metal complex may be calcined in the reducing gas atmosphere at the calcining temperature for 30 minutes to 3 hours, preferably 1 hour to 2 hours.
  • the calcination metal complex is preferably pre-leached with hydrochloric acid, nitric acid or sulfuric acid solution to remove insoluble substances and inactive catalysts.
  • the target baked metal complex can be obtained by thoroughly washing with water (including deionized water and distilled water), etc., and then recovering by centrifugation or filtration, followed by drying. .
  • the obtained fired metal complex is preferably powdered using a crystal mortar or the like into fine particles.
  • the calcined metal complex obtained in this step is a catalyst component, it can be used as it is as the electrode catalyst of the present invention.
  • an electrode catalyst having the same or higher ORR catalytic activity, durability and corrosion resistance as compared with known electrode catalysts such as Pt-based catalysts and CoTMPP catalysts can be obtained at low cost and relatively easily.
  • a simple manufacturing method can be provided.
  • Gas diffusion electrode 3-1 Outline
  • the third embodiment of the present invention is a gas diffusion electrode (electrode for fuel cell).
  • fuel cell refers to a solid polymer fuel cell (PEFC) (Polymer Electrolyte Fuel Cell) and a phosphoric acid fuel cell (PAFC) (Phosphoric Fuel Acid Cell), and a microbial fuel cell.
  • PEFC Solid polymer fuel cell
  • PAFC phosphoric acid fuel cell
  • MFC Microbial Fuel Cell
  • the gas diffusion electrode of the present invention includes an electrode catalyst and a conductive carrier that supports the electrode catalyst. Moreover, a support body can also be included as needed. Hereinafter, each component will be specifically described.
  • Electrode catalyst The gas diffusion electrode of this invention contains the electrode catalyst obtained by the electrode catalyst as described in 1st Embodiment, or the manufacturing method as described in 2nd Embodiment. Since the configuration of each electrode catalyst has been described in detail in the above embodiment, a description thereof is omitted here.
  • the electrode catalyst may be at least partially disposed on the surface of the electrode so that the gas diffusion electrode of the present invention can perform ORR between the reaction gas or the electron donating microorganisms.
  • Conductive carrier refers to a substance having conductivity and capable of supporting an electrode catalyst.
  • the material is not particularly limited as long as it has the above characteristics. For example, a carbonaceous material, a conductive polymer, a semiconductor, a metal, etc. are mentioned.
  • carbon-based substance refers to a substance containing carbon (C) as a constituent component.
  • C carbon
  • graphite activated carbon
  • carbon powder including carbon black, Vulcan XC-72R, acetylene black, furnace black, Denka black
  • carbon fiber including graphite felt, carbon wool, carbon woven fabric
  • carbon plate This includes carbon paper, carbon discs, and also fine structure materials such as carbon nanotubes, carbon nanohorns and carbon nanoclusters.
  • the “conductive polymer” is a generic term for polymer compounds having conductivity.
  • a single monomer or a polymer of two or more monomers having aniline, aminophenol, diaminophenol, pyrrole, thiophene, paraphenylene, fluorene, furan, acetylene, or a derivative thereof as a structural unit can be given.
  • polyaniline, polyaminophenol, polydiaminophenol, polypyrrole, polythiophene, polyparaphenylene, polyfluorene, polyfuran, and polyacetylene are applicable.
  • a suitable conductive support is a carbon-based material, but the present invention is not limited thereto.
  • the carrier may be composed of a single species or a combination of two or more species.
  • a carrier combining a carbon-based material and a conductive polymer, or a carrier combining a carbon powder and carbon paper, which are the same carbon-based material, can be used.
  • the shape of the carrier is not particularly limited as long as the shape can support the electrode catalyst of the first embodiment on the surface.
  • a powder shape or fiber shape having a large specific surface area per unit mass is preferable.
  • the larger the specific surface area of the support the larger the support area can be secured, the dispersibility of the catalyst component on the support surface can be improved, and more catalyst components can be supported on the surface.
  • a fine particle shape such as carbon powder and a fine fiber shape such as carbon fiber are suitable as the carrier shape.
  • a fine powder having an average particle diameter of 1 nm to 1 ⁇ m is particularly preferable.
  • carbon black having an average particle size of about 10 nm to 300 ⁇ m is suitable as a carrier in this step.
  • the carrier has a connection terminal for a lead wire connecting the fuel cell electrode and an external circuit in a part thereof.
  • Support refers to a substance that itself has rigidity and can give a certain shape to the gas diffusion electrode of the present invention.
  • the conductive carrier is in a powder form or the like, it is impossible to maintain a certain shape as a gas diffusion electrode only with the conductive carrier carrying the electrode catalyst. Further, when the conductive carrier is in a thin layer state, the carrier itself does not have rigidity. In such a case, a certain shape and rigidity are imparted as an electrode by disposing a conductive carrier carrying an electrode catalyst on the surface of the support.
  • the support is not an essential component of the gas diffusion electrode of the present invention.
  • the conductive carrier itself has a certain shape and rigidity, such as a carbon disk, it is possible to maintain a certain shape as a gas diffusion electrode only by the conductive carrier carrying the electrode catalyst.
  • the electrolyte material itself may give a certain shape and rigidity to the gas diffusion electrode.
  • the support is not necessarily required. Therefore, the support may be added to the gas diffusion electrode of the present invention as necessary.
  • the material of the support is not particularly limited as long as the electrode is rigid enough to maintain a certain shape. It does not matter whether it is an insulator or a conductor. In the case of an insulator, for example, glass, plastic, synthetic rubber, ceramics, or water- or water-repellent treated paper or plant pieces (including wood pieces), animal pieces (eg bone pieces, shells, sponges) Can be mentioned.
  • An insulator for example, glass, plastic, synthetic rubber, ceramics, or water- or water-repellent treated paper or plant pieces (including wood pieces), animal pieces (eg bone pieces, shells, sponges) Can be mentioned.
  • a support having a porous structure is more preferable because the specific surface area for joining the conductive support carrying the electrode catalyst is increased and the mass activity of the electrode can be increased. Examples of the support having a porous structure include porous ceramics, porous plastics, animal pieces, and the like.
  • a carbonaceous material for example, including carbon paper, carbon fiber, and carbon rod
  • metal, conductive polymer, and the like can be given.
  • the support When the support is a conductor, it can function as a support and a current collector by disposing a conductive carrier carrying an electrode catalyst on its surface.
  • the shape of the support usually reflects the shape of the gas diffusion electrode.
  • the shape of the support is not particularly limited as long as it can serve as an electrode. What is necessary is just to determine suitably according to the shape etc. of a fuel cell. For example, (substantially) flat (including thin layer), (substantially) columnar, (substantially) spherical, or a combination thereof may be mentioned.
  • Electrocatalyst Support Method As a method for supporting the electrode catalyst on a conductive carrier, a method known in the art can be used. For example, a method of fixing the fired metal complex on the surface of the conductive support using an appropriate fixing agent can be mentioned.
  • the fixing agent is preferably conductive, but is not limited.
  • a conductive polymer solution obtained by dissolving the conductive polymer in a suitable solvent, a polytetrafluoroethylene (PTFE) dispersion, or the like can be used as the fixing agent.
  • Such a sticking agent is applied or sprayed on the surface of the conductive support and / or the surface of the electrode catalyst to mix them together, or impregnated in a solution of the sticking agent and then dried to conduct the electrocatalyst.
  • Loading on a functional carrier can be achieved.
  • Gas diffusion electrode formation method As a method for forming the gas diffusion electrode, a method known in the art can be used. For example, a conductive carrier carrying an electrode catalyst is mixed with a PTFE dispersion (for example, Nafion (registered trademark; DuPont) solution), etc., molded into an appropriate shape, and then subjected to heat treatment to form a gas diffusion electrode. Can be formed. When forming an electrode on the surface of a solid polymer electrolyte membrane or electrolyte matrix layer, such as PEFC or PAFC, the mixed solution is formed into a sheet shape, and proton conductivity is formed on the membrane bonding surface of the formed electrode sheet.
  • a PTFE dispersion for example, Nafion (registered trademark; DuPont) solution
  • a fluororesin ion-exchange membrane solution or the like having the above After applying or impregnating a fluororesin ion-exchange membrane solution or the like having the above, it may be hot-pressed on both sides of the membrane and bonded to the membrane.
  • a fluororesin ion-exchange membrane solution or the like having the above, it may be hot-pressed on both sides of the membrane and bonded to the membrane.
  • Nafion, Flemion registered trademark; Asahi Glass Co., Ltd.
  • the fluorine resin ion exchange membrane having proton conductivity can be used for the fluorine resin ion exchange membrane having proton conductivity.
  • heat treatment can be performed to form a gas diffusion electrode.
  • a mixed ink or mixed slurry of a solution of proton conductive ion exchange membrane (for example, Nafion solution) and a conductive carrier carrying an electrode catalyst is applied to the surface of a support, a solid polymer electrolyte membrane, an electrolyte matrix layer, or the like. May be formed.
  • a solution of proton conductive ion exchange membrane for example, Nafion solution
  • a conductive carrier carrying an electrode catalyst is applied to the surface of a support, a solid polymer electrolyte membrane, an electrolyte matrix layer, or the like. May be formed.
  • a gas diffusion electrode that has the same or higher catalytic activity, durability, and corrosion resistance than a Pt-based catalyst, and that can be stably supplied at a lower cost than a conventional Pt-based catalyst. Can be provided.
  • Fuel cell 4-1. Outline The fourth embodiment of the present invention is a fuel cell.
  • a fuel cell according to the present invention includes the gas diffusion electrode described in the third embodiment.
  • the fuel cell of the present embodiment can be suitably used for a hydrogen fuel cell or MFC as described above.
  • a hydrogen fuel cell is a fuel cell that obtains electrical energy from hydrogen and oxygen based on the reverse action of water electrolysis.
  • PEFC, PAFC, alkaline fuel cell (AFC), molten carbonate fuel cell (MCFC: Molten Cabonate Fuel Cell), solid oxide fuel cell (SOFC), etc. are known, but PEFC and PAFC are preferred for the fuel cell of the present invention.
  • PEFC is a proton conductive ion exchange membrane
  • PAFC is a fuel cell using phosphoric acid (H 3 PO 4 ) impregnated in a matrix layer as an electrolyte material.
  • Electron-donating microorganisms include the genus Shewanella (eg, Shewanella leuhica; S. loihica, Shewanella oneidensis; S. oneidensis, Shewanella putrefaciens; S. putrefaciens, and S. algae).
  • Pseudomonas genus eg P. aeruginosa
  • Rhodoferax genus eg Rhoferferferax ferrireducens
  • Geobacter genus eg G. sulfurreducens, G. metallireducens; G. metallireducens
  • the fuel cell of the present invention may have a known configuration in each fuel cell except that the gas diffusion electrode of the third embodiment is used as an electrode.
  • “Technology for Fuel Cell”, edited by the IEEJ Fuel Cell Power Generation Next Generation System Technology Research Special Committee, Ohm, H17, Watanabe, K., J. Biosci. Bioeng., 2008, .106: 528-536 It can have the structure described in the above.
  • the gas diffusion electrode of the third embodiment can be used for either the anode (fuel electrode) or the cathode (air electrode).
  • the electrode catalyst of the present invention included in the electrode catalyzes the reaction of H 2 ⁇ H + + 2e ⁇ of hydrogen gas as a fuel. , Donate electrons to the anode.
  • the cathode 1 / 2O 2 + 2H + + 2e of the oxygen gas as an oxidizing agent - ⁇ H 2 O to catalyze the reaction of.
  • the gas diffusion electrode of the present invention is mainly used as a cathode that causes the same electrode reaction as that of a hydrogen fuel cell.
  • Example 1 Preparation of electrode catalyst> Experimental Example 1 Preparation of Co-2,6-diaminopyridine polymer (CoDAPP) catalyst
  • CoDAPP Co-2,6-diaminopyridine polymer
  • the CoDAPP catalyst followed the method of the second embodiment of the present invention.
  • 2,6-diaminopyridine monomer (Aldrich) and oxidizing agent ammonium peroxydisulfate (APS) (Wako) were mixed at a molar ratio of 1: 1.5 and stirred. Specifically, 5.45 g of 2,6-diaminopyridine and 1 g of sodium hydroxide were dissolved in 400 mL of distilled water, and then 27.6 g of APS and 100 mL of water were added.
  • the suspension was subjected to ultrasonic mixing with sonicator ultrasonic probe systems (As One Co., Ltd.) for 1 hour and further stirred at 60 ° C. for 2 hours, and then the solution was evaporated.
  • the remaining powder of the polymer metal complex consisting of 2,6-diaminopyridine polymer and cobalt was ground in a crystal mortar.
  • the polymer metal complex was baked at 700 ° C. for 1.5 hours in an ammonia gas atmosphere.
  • the obtained calcined metal complex was subjected to ultrasonic pre-leach with a 12 N hydrochloric acid solution for 8 hours to remove insoluble substances and inactive substances, and then thoroughly washed with deionized water.
  • the calcined metal complex which is the electrode catalyst of the present invention was recovered by filtration and dried at 60 ° C.
  • Example 2 Preparation of Fe-2,6-diaminopyridine polymer (FeDAPP) catalyst Except for using iron (iron nitrate (II); Wako Pure Chemical Industries) instead of cobalt nitrate as the catalyst metal atom, The same operation as in Example 1 (Experimental Example 1) was performed.
  • iron iron nitrate (II); Wako Pure Chemical Industries
  • Example 3 Preparation of Fe / Co-2,6-diaminopyridine polymer (Fe / CoDAPP) catalyst Except that iron nitrate (III) (Wako Pure Chemical Industries) was used in addition to cobalt nitrate as the catalyst metal atom. Then, the same operation as in Example 1 (Experimental Example 1) was performed. The molar mixing ratio of cobalt nitrate and iron (III) nitrate was 1: 1, and the molar mixing ratio of PAPA / Co (NO3) 2 / Fe (NO3) 3 was 8: 1: 1.
  • CoTMPP catalyst was prepared by the method of Deng et al. (Liu Deng, Ming Zhou, Chang Liu, Ling Liu, Changyun Liu, Shaojun Dong, 2010, Talanta 81: 444-448 ). In the preparation of the CoTMPP catalyst, since it is in a mixed state with carbon that becomes a conductive carrier at the time of firing, as a result, the electrode is prepared simultaneously with the catalyst preparation. In the present specification, an electrode including such a CoTMPP catalyst is referred to as a “CoTMPP electrode”.
  • the carbon fine particle Vulcan XC-72R was sonicated in a 6M nitric acid solution for 1 hour, then treated at 100 ° C. for 6 hours, and then washed with deionized water three times. Finally, it was collected by centrifugation at 3000 rpm and dried under vacuum.
  • CoPPy Catalyst Synthesis of polypyrrole doped with 4-toluenesulfonic acid (TsOH) was performed in accordance with the method disclosed in Non-Patent Document 2.
  • the CoPPy catalyst is also mixed with carbon that becomes a conductive carrier at the time of calcination, like the CoTMPP catalyst. Therefore, an electrode including the CoPPy catalyst is referred to as a “CoPPy electrode” in this specification.
  • Vulcan XC-72R was treated in the same manner as in Comparative Example 1. Then 3 mmol of pyrrole and 100 mL of double distilled water were added and the mixture was stirred for another 30 minutes. Subsequently, 100 mL of 0.06 mol / L APS solution and 0.1902 g of 4-toluenesulfonic acid (TsOH) were added. The mixture was then stirred at room temperature for 4 hours, after which the mixture was filtered and washed alternately with double distilled water and alcohol at least three times. Finally, it was dried for 12 hours under vacuum, and the remaining powder was ground in a crystal mortar.
  • TsOH 4-toluenesulfonic acid
  • Pt catalyst purchased from Tanaka Kikinzoku Kogyo Co., Ltd. 20% Pt / C nanoparticle as an electrode by which the commercially available Pt was carry
  • an electrode including a Pt catalyst such as a Pt-supported carbon electrode is referred to as a “Pt electrode”.
  • Example 2 Catalytic activity (1)> Bipotentiostat using a rotating ring-disk electrode (RRDE) for the catalytic activity of the oxygen reduction reaction (ORR) of the catalyst included in each electrode prepared in Example 1 (excluding Experimental Example 2) Verified by Pine Instrument).
  • RRDE rotating ring-disk electrode
  • ORR oxygen reduction reaction
  • Example 2 mg each of the electrode catalyst (CoDAPP catalyst and FeDAPP catalyst) and the electrode (CoTMPP electrode, CoPPy electrode and Pt electrode) prepared in Example 1 were each 20 ⁇ L of Nafion (registered trademark) solution (5% by weight; DuDPont) and 1 mL.
  • the catalyst ink or electrode ink was prepared by mixing with ethanol and blending in an ultrasonic bath for 30 minutes and dispersing uniformly.
  • an RRDE electrode carrying each catalyst or electrode at 1 mg / cm 2 was obtained.
  • an electrode using RRDE as a conductive carrier and CoDAPP or FeDAPP as an electrode catalyst an electrode including such a CoDAPP catalyst or FeDAPP catalyst is referred to as a “CoDAPP electrode” or an “FeDAPP electrode”, respectively in this specification).
  • a CoTMPP electrode, a CoPPy electrode, and a Pt electrode using RRDE as a further conductive carrier is referred to as a “CoDAPP electrode” or an “FeDAPP electrode”, respectively in this specification.
  • a CoTMPP electrode, a CoPPy electrode, and a Pt electrode using RRDE as a further conductive carrier.
  • Electrochemical measurement of electrode The catalyst current was evaluated in oxygen-saturated 0.05M H 2 SO 4 , 0.2M K 2 H 2 PO 4 / KH 2 PO 4 and 0.1M KOH solution (pH 1). Then, measurement was performed at a potential scanning speed of 5 mV / s at room temperature and a rotation speed of 1500 rpm at room temperature.
  • n 4i D / (i D + i R / N) (1)
  • i D is the sensitive current on the disk
  • i R is the sensitive current on the ring
  • N is the collection efficiency determined by the electrode dimensions (disk outer diameter, ring outer diameter and inner diameter). In this embodiment, it is 0.19.
  • a scanning potential range of 0.8 to ⁇ 0.3 V was selected for SCE when the pH value of the RRDE electrode was equal to 1.
  • [result] 1. Mixing ratio of 2,6-diaminopyridine polymer and cobalt nitrate (molar ratio of raw material monomer and catalytic metal atom) and ORR catalytic activity at CoDAPP electrode and molar ratio of raw material monomer and cobalt with 2,6-diaminopyridine polymer and cobalt nitrate
  • the electrode catalyst CoDAPP
  • Figure 1 shows the results.
  • a, b, c, and d are 2,6-diaminopyridine polymer and a raw material monomer: cobalt molar ratio of 4: 1, 6: 1, 8: 1, and 10: 1, respectively.
  • the ORR catalytic activity of a CoDAPP electrode including a calcined metal complex CoDAPP prepared by mixing cobalt nitrate as an electrode catalyst is shown, and e shows the ORR catalytic activity of a Pt electrode.
  • the CoDAPP electrode had a larger catalyst current than the Pt electrode even when 2,6-diaminopyridine polymer and cobalt nitrate were mixed at any mixing ratio.
  • a, b, c, and d indicate a CoDAPP electrode, a CoTMPP electrode, a CoPPy electrode, and a Pt electrode, respectively.
  • the number (n) of electron transfer between ORRs calculated by the above equation (1) was 3.98 for the CoDAPP electrode, 3.91 for the CoTMPP electrode, 3.68 for the CoPPy electrode, and 3.99 for the Pt electrode. From this result, it can be seen that most of the products of the oxygen reduction reaction are H 2 O (4-electron reduction).
  • FIG. 2 demonstrates that the CoDAPP electrode is inferior to the Pt electrode in falling potential, but the falling amount is superior, so that a larger current can be obtained as an oxygen reduction catalyst.
  • Example 3 Catalytic activity (2)> The FeDAPP catalyst prepared in Experimental Example 2 of Example 1 was applied on the surface of RRDE using the same method as in Example 2, and the electrode using such RRDE as a conductive support and FeDAPP as an electrode catalyst (such as The electrode containing the FeDAPP catalyst is referred to as “FeDAPP electrode” in this specification), and the ORR catalytic activity of the FeDAPP catalyst was verified.
  • FIG. 3 shows that FeDAPP catalyst has higher falling potential and higher falling amount than CoDAPP catalyst, and therefore FeDAPP has a higher ability as a catalyst than CoDAPP.
  • Example 4 Catalytic activity (3)> Whether or not the electrode catalyst has two or more different catalytic metals coordinated with each other compared with a single catalytic metal coordinated was examined.
  • Electrode catalyst coordinating two or more different catalytic metals the Fe / CoDAPP catalyst prepared in Experimental Example 3 of Example 1 was used on the surface of RRDE using the same method as in Example 2. And an electrode using Fe / CoDAPP as an electrode catalyst (an electrode including such an Fe / CoDAPP catalyst is referred to as an “Fe / CoDAPP electrode” in this specification). Further, the CoDAPP electrode prepared in Example 2 and the FeDAPP electrode prepared in Example 3 were used as the electrode catalyst for coordinating a single catalytic metal for comparison.
  • the Fe / CoDAPP electrode had a falling potential equal to or higher than the FeDAPP electrode and CoDAPP electrode, and the amount of falling was excellent. Therefore, even an electrode catalyst that coordinates two or more different catalytic metals has oxygen reduction catalytic ability, and in particular, in the case of an electrode catalyst that coordinates Fe and Co, each coordinates independently. It was revealed that the oxygen reduction catalytic ability was higher than that of the electrode catalyst.
  • Example 5 Content ratio of carbon, nitrogen and catalyst metal in each electrode catalyst>
  • the elemental composition of the electrode catalyst prepared in Example 1 or the gas diffusion electrode containing the same was analyzed using XPS analysis, and carbon (C), nitrogen (N) and cobalt (Co ) Content ratio was examined.
  • the XPS measurement was performed using an XPS apparatus (Axis Ultra HAS; Kratos Analytical) and monochromatic Al X-rays (10 KV) as excitation X-rays. Measurements and narrow scan spectra for C, N, O and Co were performed on the CoDAPP catalyst, CoTMPP electrode and CoPPy electrode.
  • CoTMPP / C and CoPPy / C indicate a CoTMPP electrode and a CoPPy electrode using carbon fine particles as a conductive carrier, respectively.
  • the element ratio of nitrogen to carbon in the CoDAPP catalyst of the present invention after pickling treatment with hydrochloric acid (acid washing) was 0.12 in terms of molar ratio (N / C). Further, the elemental ratio of the catalytic metal (here, cobalt Co) to nitrogen was 0.06 in terms of molar ratio (Co / N). Furthermore, it was revealed that the molar ratio of nitrogen to catalyst metal (N / Co%) was 10% or more. This molar ratio is clearly higher than that of the known CoTMPP electrode and CoPPy electrode, and is more than 5 times and 1.75 times the respective molar ratio. This result shows that the 2,6-diaminopyridine polymer constituting the CoDAPP catalyst can contain a large amount of nitrogen as a ligand (coordinating atom) compared to the electrode catalyst included in other gas diffusion electrodes. Suggests.
  • Example 6 Content ratio of nitrogen and catalytic metal in CoDAPP catalyst> Calculate the amount of 2,6-diaminopyridine polymer and cobalt nitrate from the molar ratio so that the molar ratio of 2,6-diaminopyridine and cobalt is 6: 1, 8: 1, 10: 1
  • the elemental composition of the CoDAPP catalyst thus prepared was similarly analyzed using XPS analysis, and the content ratio of nitrogen (N) and cobalt (Co) was examined.
  • the CoDAPP catalyst was prepared by the method described in Experimental Example 1 of Example 1, and the polymer metal complex was calcined at 700 ° C. for 1 hour in a nitrogen gas atmosphere instead of in an ammonia gas atmosphere. What was prepared by the method similar to Example 1 was used. The analysis of the element composition was in accordance with the method described in Example 5.
  • the CoDAPP catalyst of the present invention had a molar ratio of nitrogen to carbon (N / C) ranging from 0.11 to 0.15. Further, the elemental ratio of the catalyst metal to nitrogen after the pickling treatment (acid washing) was 0.03 to 0.49 in terms of molar ratio (Co / N).
  • the electrode catalyst of the present invention has an element ratio of nitrogen to carbon of 0.1 to 0.2 in terms of molar ratio, and an element ratio of metal to nitrogen after acid cleaning of 0.03 or more in molar ratio. It was shown that there is.
  • the N / C ratio can be significantly improved to exceed 0.1. It was also revealed that high activity was obtained even when the N / C ratio was 0.1 or more, but the activity peaked out when it exceeded 0.2.
  • Example 7 Stability of catalyst activity> The loss of catalytic activity at the CoDAPP electrode was verified. [Method] Using a CoDAPP electrode, the rotation speed was 500 rpm under a scanning speed of 5 mV / s. In order to prevent the loss of catalyst between the rotation steps, the ratio of Nafion to catalyst was shifted to 1: 1.
  • Example 8 Verification of power generation capability> The power generation capacity of each gas diffusion electrode was verified by a single tank type MFC.
  • the graphite felt modified with carbon nanotubes (Japanese Patent Application No. 2010-257390) was used for the anode.
  • an Ag / AgCl electrode (Hokuto Denko) was attached as a reference electrode.
  • Electron-donating microorganism As the electron-donating microorganism, a microorganism contained in paddy soil collected in Kamaishi City, Japan was used.
  • the electrolytic cell used in the present example is a single electrolytic cell, and an electrolytic solution to which an electron donating microorganism and a nutrient substrate are added is accommodated in the electrolytic cell.
  • the specific configuration of the electrolytic cell is as follows: 12 mL of buffer solution containing 200 mM K 2 HPO 4 / KH 2 PO 4 (pH 6.8) is placed in an electrolytic cell having a capacity of 15 mL as a nutrient substrate.
  • An organic mixed substrate in which starch: peptone: fishmeal was mixed 3: 1: 1 (289 g COD / L, COD chemical oxygen demand) was used.
  • a separator paper towel was inserted between the anode and the cathode in order to prevent both electrodes from being short-circuited.
  • the anode and cathode were connected to an external circuit via a resistor (10 k ⁇ ).
  • the organic mixed substrate was added to the electrolytic cell at 0.2 to 0.4 mL per day. Subsequently, the medium was purged with nitrogen for 5 minutes. 500 mg (wet weight) of the paddy soil was added to the electrolytic cell and cultured anaerobically at 30 ° C. Thereafter, 0.2 mL of the organic mixed substrate (300 g COD / L) was added to the electrolytic cell per day. The anolyte solution was run for 2 weeks with gentle stirring at about 50 rpm, and using a potentiostat (HA-1510, Hokuto Denko), the current at various total voltages was measured and the current / current at each gas diffusion electrode was measured. A voltage (IV) curve and an output curve were obtained.
  • FIG. 5A shows a current / voltage curve of a microbial fuel cell when each gas diffusion electrode is used as a cathode
  • FIG. 5B shows an output.
  • Example 9 Activity evaluation of cathode in microbial fuel cell> [Method] A reference electrode is inserted into the MFC of Example 7 to determine whether the increase in power generation capacity in the fuel cell is due to an increase in cathode activity, and the anode and cathode currents are arbitrarily set with a potentiostat with respect to the reference electrode during power generation. While measuring.
  • FIG. This figure shows the anode and cathode polarization curves of the fuel cell measured using an Ag / AgCl electrode as a reference electrode.
  • Curves indicated by black plots (a) to (d) are anode polarization curves
  • curves indicated by white plots (a ′) to (d ′) are cathode polarization curves.
  • a comparison of the cathodic polarization curves shows that a large current was obtained at the highest potential using the CoDAPP electrode.
  • the efficiency of the anode was improved because the electrode consumed the electrons efficiently.
  • Example 10 Cyclic voltammogram when each electrode is used as a cathode> Cyclic voltammograms were measured by MFC using each electrocatalyst in Example 7 as a cathode, and electron transfer characteristics in the presence of a mixture of microorganisms were examined.
  • the cyclic voltammogram is a measurement of the current flowing in the electrochemical cell by continuously changing the potential of the working electrode with respect to the reference electrode. The redox potential of this reaction system is obtained from the midpoint of the + and-peaks at that time.
  • FIG. A is a cyclic voltammogram when a CoDAPP electrode is used
  • B is a Pt electrode
  • C is a CoTMPP electrode as a cathode.
  • the solid line is the measurement result in the presence of oxygen
  • the broken line is the measurement result in the absence of oxygen.
  • Example 11 Conductivity of electrode catalyst> [Method]
  • the CoDAPP catalyst powder prepared by the method described in Experimental Example 1 of Example 1 was compacted into cylindrical pellets having a diameter of 10 mm and a thickness of 2 mm using a die. The compacting was performed at a pressure of 10 MPa for 30 seconds.
  • the conductivity of the prepared pellets was measured using a Loresta-EP low resistivity meter (Mitsubishi Chemical) and a four-probe probe (PSP probe, Mitsubishi Chemical).
  • the conductivity was a normal distribution centered around 5 S / cm and was in the range of 0.1 S / cm to 10 S / cm.
  • Example 11 Specific surface area of electrode catalyst> [Method] The specific surface area was measured by a nitrogen BET adsorption method. Specifically, first, the CoDAPP catalyst prepared by the method described in Example 1 and a 20% Pt / C catalyst (manufactured by Tanaka Kikinzoku) as a reference were heated at 200 ° C. for 1 hour at 10 ⁇ 3 Pa and vacuum dried. Then, moisture and adsorbate in the sample were removed. For each of the above-treated catalysts, an isotherm adsorption line was measured using Autosorb-3 (manufactured by Quantachrome), and linear conversion was performed by the BET method to calculate a specific surface area.
  • Autosorb-3 manufactured by Quantachrome
  • FIG. A is an isothermal adsorption line when a CoDAPP catalyst is used and B is a 20% Pt / C catalyst used as a cathode.
  • the specific surface area of the CoDAPP catalyst was 568 m 2 / g.

Abstract

The purpose of the invention is to develop and provide an electrode catalyst having catalyst activity in oxygen reduction reactions comparable to or higher than that of Pt based catalysts, as well as having durability and corrosion resistance, and which it is possible to supply inexpensively and consistently; as well as a fuel cell electrode employing the same, and a fuel cell furnished with the electrode. An electrode catalyst that includes as the catalyst component a calcined metal complex obtained by calcination of a polymer-metal complex comprising a diaminopyridine polymer and a catalyst metal, a fuel cell electrode employing the same, and a fuel cell furnished with the electrode are provided.

Description

電極触媒及びその製造方法Electrode catalyst and method for producing the same
　本発明は、電極触媒及びその製造方法、該触媒を含むガス拡散電極、並びにそれを用いた燃料電池に関する。 The present invention relates to an electrode catalyst and a production method thereof, a gas diffusion electrode containing the catalyst, and a fuel cell using the same.
　従来の化石燃料に替わる新たなエネルギーシステムとして燃料電池が注目されている。燃料電池には、固体高分子型燃料電池（Polymer Electrolyte Fuel Cell:以下「PEFC」とする）やリン酸燃料電池（Phosphoric Acid Fuel Cell；以下「PAFC」とする）のように水素を電子供与体とする水素燃料電池や、電子供与微生物を電子供与体とする微生物燃料電池（Microbial Fuel Cell；以下「MFC」とする）等が知られているが、いずれの燃料電池もアノード(燃料極)及び／又はカソード(空気極)に電極触媒を含み、その触媒作用によって水素ガス及び／又は酸素ガスをイオン化している。そのような電極触媒には、白金（Pt）や白金合金等のようなPt系触媒が一般的に知られており、当該触媒成分を炭素系担体に担持したもの（白金担持カーボン）がガス拡散電極（燃料電池用電極）として広く使用されている。 Fuel cells are attracting attention as a new energy system that replaces conventional fossil fuels. Fuel cells include hydrogen as an electron donor, such as polymer electrolyte fuel cells (hereinafter referred to as “PEFC”) and phosphoric acid fuel cells (hereinafter referred to as “PAFC”). And a microbial fuel cell (Microbial 電池 Fuel Cell; hereinafter referred to as “MFC”) using an electron-donating microorganism as an electron donor are known. An electrode catalyst is included in the cathode (air electrode), and hydrogen gas and / or oxygen gas is ionized by the catalytic action. As such an electrode catalyst, a platinum catalyst such as platinum (Pt) or a platinum alloy is generally known, and the catalyst component supported on a carbon carrier (platinum-supported carbon) is gas diffused. Widely used as an electrode (electrode for fuel cell).
　しかし、Ptは、高価かつ希少な金属であることから、燃料電池の民生用用途への普及の阻害要因となるだけでなく、将来の量産化に対応し得るだけの資源供給量にも問題がある。 However, since Pt is an expensive and rare metal, it not only hinders the spread of fuel cells to consumer use, but also has a problem with the amount of resources that can be used for future mass production. is there.
　それ故、燃料電池分野においては、Pt触媒量の低減やPtに代わる低廉で安定的に供給可能な新たな触媒成分の開発が急務となっている。例えば、特許文献１及び２並びに非特許文献１及び２では、Pt代替触媒としてポリマーと触媒金属からなる金属錯体をベースとする電極触媒が開示されている。 Therefore, in the fuel cell field, there is an urgent need to reduce the amount of Pt catalyst and to develop a new catalyst component that can be stably supplied at low cost instead of Pt. For example, Patent Documents 1 and 2 and Non-Patent Documents 1 and 2 disclose electrode catalysts based on metal complexes composed of a polymer and a catalyst metal as Pt substitute catalysts.
　特許文献１では、高い触媒活性を示し、かつ長寿命の電極触媒として、触媒成分とインドール、イソインドール、ナフトピロール、ピロロピリジン、ベンズイミダゾール、プリン、カルバゾール、フェノキサジン、及びフェノチアジンからなる群から選ばれる少なくとも1種の繰り返し単位構造を有する導電性重合体と金属イオンからなる非白金型導電性重合体金属錯体を含む電極触媒、及びそれを用いるガス拡散電極が開示されている。 In Patent Document 1, a catalyst component and an indole, isoindole, naphthopyrrole, pyrrolopyridine, benzimidazole, purine, carbazole, phenoxazine, and phenothiazine are selected as an electrocatalyst having a high catalytic activity and a long life. An electrode catalyst comprising a non-platinum type conductive polymer metal complex comprising a conductive polymer having at least one repeating unit structure and a metal ion, and a gas diffusion electrode using the same are disclosed.
　特許文献２では、高い比表面積を有し、分子内に－NH2、＝NH、＝N－から選択される化学構造を2個以上含有し、平面構造を有する配位子と、金属からなる多孔質骨格構造を有する配位高分子金属錯体を熱処理してなる燃料電池用触媒が開示されている。 In Patent Document 2, it has a high specific surface area, contains two or more chemical structures selected from —NH 2 , ═NH, and ═N— in the molecule, and has a planar structure and a metal. A fuel cell catalyst obtained by heat-treating a coordination polymer metal complex having a porous skeleton structure is disclosed.
　非特許文献１では、鉄（II）フタロシアニン（FePc）及びコバルト－テトラメトキシフェニルポルフィリン（Cobalt TetraMethoxyPhenylPorphyrin、以下「CoTMPP」とする）ベースの酸素還元触媒をMFCのカソードに用いた発明が開示されている。 Non-Patent Document 1 discloses an invention in which an iron (II) phthalocyanine (FePc) and cobalt-tetramethoxyphenylporphyrin (Cobalt リ ン TetraMethoxyPhenylPorphyrin, hereinafter referred to as “CoTMPP”)-based oxygen reduction catalyst is used as an MFC cathode. .
　非特許文献２では、4-トルエンスルホン酸をドープしたCo-ポリピロール（Cobalt PolyPyrrole；以下「CoPPy」とする）を白金代替触媒としてPEFCのカソードに用いることで、プロトン伝導性イオン交換膜の性能が向上したことが開示されている。 In Non-Patent Document 2, the performance of proton-conducting ion exchange membranes can be achieved by using Co-polypyrrole doped with 4-toluenesulfonic acid (Cobalt PolyPyrrole; hereinafter referred to as “CoPPy”) as a platinum substitute catalyst for the cathode of PEFC. An improvement is disclosed.
　金属錯体において、金属原子は、一般的に窒素原子（N）と配位結合し易く、ポリマー内で配位子として機能し得るN原子の数が多いほど触媒活性が向上することから、その数を増加させる試みがなされてきた(非特許文献２)。しかし、上記先行技術の金属錯体では、ポリマーを構成するモノマーの構造上、ポリマー内における配位子となるN原子数が必ずしも多いとは言えなかった。 In metal complexes, metal atoms are generally more easily coordinated with nitrogen atoms (N), and the greater the number of N atoms that can function as a ligand in the polymer, the more the catalyst activity improves. Attempts have been made to increase (Non-patent Document 2). However, in the metal complex of the above prior art, it cannot be said that the number of N atoms serving as a ligand in the polymer is necessarily large due to the structure of the monomer constituting the polymer.
　また、上記先行技術の金属錯体においては、ポリマー内における配位子となるN原子数が十分でないという問題に加えて、金属と配位結合し得るN原子を含む配位子となる分子又はモノマーの寸法が大きい等の理由により、配位結合し得るN原子の割合が少なく、上記金属錯体では配位結合している金属の量が少ないという問題があった。つまり、これまでは窒素／炭素の元素比、及び金属／窒素の元素比が共に十分に大きい電極触媒が存在せず、従来のPt触媒と同等以上の触媒機能を発揮し得なかった。 In the above prior art metal complex, in addition to the problem that the number of N atoms serving as a ligand in the polymer is not sufficient, a molecule or monomer serving as a ligand containing an N atom capable of coordinating with a metal. Because of the large size of the metal complex, there is a problem that the proportion of N atoms that can be coordinated is small, and the metal complex has a small amount of metal that is coordinated. That is, until now, there has been no electrode catalyst in which both the nitrogen / carbon element ratio and the metal / nitrogen element ratio are sufficiently large, and the catalyst function equal to or higher than that of the conventional Pt catalyst could not be exhibited.
特開2008-311048JP2008-311048 特開2010-15972JP2010-15972
　本発明は、上記問題点を鑑み、Pt系触媒と同等又はそれよりも高い酸素還元反応（Oxygen Reduction Reaction；以下「ORR」とする）触媒活性、耐久性及び耐食性を有し、かつ低廉で安定的に供給が可能な電極触媒と、それを用いたガス拡散電極、並びにその電極を備えた、エネルギー変換効率能が高く、かつ長寿命で低廉な燃料電池を提供することを目的とする。 In view of the above problems, the present invention has an oxygen reduction reaction (Oxygen Reduction Reaction; hereinafter referred to as “ORR”) catalytic activity, durability and corrosion resistance equivalent to or higher than that of a Pt-based catalyst, and is inexpensive and stable. It is an object of the present invention to provide an electrocatalyst that can be supplied automatically, a gas diffusion electrode using the electrode catalyst, and a fuel cell having the energy conversion efficiency, long life, and low cost provided with the electrode.
　本発明者らは、上記課題を解決するために、新たな電極触媒の開発を行った。その結果、ジアミノピリジンポリマーと触媒金属からなる金属錯体を触媒成分とした電極が、Pt電極よりもエネルギー変換効率が高く、高出力電流を発生できることを見出した。ジアミノピリジンポリマーは、配位子となり得る窒素原子数が従来のポリマー金属錯体と比較して多く、より多数の触媒金属の配位が可能なことが、上記効果をもたらしたと考えられる。発明は、当該知見に基づくものであり、具体的には、以下の発明を提供する。 The present inventors have developed a new electrode catalyst in order to solve the above problems. As a result, it was found that an electrode using a metal complex composed of a diaminopyridine polymer and a catalyst metal as a catalyst component has higher energy conversion efficiency than a Pt electrode and can generate a high output current. The diaminopyridine polymer has a larger number of nitrogen atoms that can serve as a ligand than the conventional polymer metal complex, and it is considered that a larger number of catalyst metals can be coordinated to bring about the above effect. The invention is based on the findings, and specifically provides the following inventions.
（１）炭素、窒素、及び触媒金属を含んだ電極触媒であって、炭素に対する窒素の元素比がモル比で0.1以上0.2以下であり、かつ、酸洗浄後の窒素に対する触媒金属の元素比がモル比で0.03以上であることを特徴とする前記電極触媒。 (1) An electrode catalyst containing carbon, nitrogen, and catalytic metal, wherein the elemental ratio of nitrogen to carbon is 0.1 or more and 0.2 or less in molar ratio, and the elemental ratio of catalytic metal to nitrogen after acid cleaning is The electrode catalyst having a molar ratio of 0.03 or more.
（２）前記窒素に対する触媒金属の元素比がモル比で0.05以上である、（１）に記載の電極触媒。 (2) The electrode catalyst according to (1), wherein an element ratio of the catalyst metal to nitrogen is 0.05 or more in terms of molar ratio.
（３）炭素、窒素、及び触媒金属を含んだ電極触媒であって、窒素原子に配位した触媒金属の含有率が0.4モル％以上であり、かつ、窒素原子の含有率が6.0モル％以上であることを特徴とする前記電極触媒。 (3) An electrocatalyst containing carbon, nitrogen, and a catalytic metal, wherein the content of the catalytic metal coordinated to the nitrogen atom is 0.4 mol% or more, and the content of the nitrogen atom is 6.0 mol% or more The electrode catalyst as described above.
（４）前記触媒金属が２種類以上の異なる金属である、（１）～（３）のいずれかに記載の電極触媒。 (4) The electrode catalyst according to any one of (1) to (3), wherein the catalyst metal is two or more different metals.
（５）前記触媒金属が遷移金属である、（１）～（４）のいずれかに記載の電極触媒。 (5) The electrode catalyst according to any one of (1) to (4), wherein the catalyst metal is a transition metal.
（６）電極触媒の導電率が0.1s/cm以上である、（１）～（５）のいずれかに記載の電極触媒。 (6) The electrode catalyst according to any one of (1) to (5), wherein the conductivity of the electrode catalyst is 0.1 s / cm or more.
（７）電極触媒の比表面積が500m2/g以上である、（１）～（６）のいずれかに記載の電極触媒。 (7) The electrode catalyst according to any one of (1) to (6), wherein the electrode catalyst has a specific surface area of 500 m 2 / g or more.
（８）ジアミノピリジン、ジアミノピリジン誘導体、トリアミノピリジン、トリアミノピリジン誘導体、テトラアミノピリジン及びテトラアミノピリジン誘導体からなる群から選択される１又は２以上をアニオン重合させて重合体を得る第一工程、前記重合体と触媒金属塩との混合により前記重合体に触媒金属を配位させて重合体金属錯体を得る第二工程、及び重合体金属錯体を650～800℃にて焼成して焼成金属錯体を得る第三工程を含む電極触媒の製造方法。 (8) First step of obtaining a polymer by anionic polymerization of one or more selected from the group consisting of diaminopyridine, diaminopyridine derivative, triaminopyridine, triaminopyridine derivative, tetraaminopyridine and tetraaminopyridine derivative. A second step of obtaining a polymer metal complex by coordinating a catalyst metal to the polymer by mixing the polymer and a catalyst metal salt; and firing the polymer metal complex at 650 to 800 ° C. The manufacturing method of the electrode catalyst including the 3rd process of obtaining a complex.
（９）前記第三工程を還元性ガス雰囲気下又は不活性ガス雰囲気下行う、（８）に記載の電極触媒の製造方法。 (9) The method for producing an electrode catalyst according to (8), wherein the third step is performed in a reducing gas atmosphere or an inert gas atmosphere.
（１０）ジアミノピリジン、ジアミノピリジン誘導体、トリアミノピリジン、トリアミノピリジン誘導体、テトラアミノピリジン及びテトラアミノピリジン誘導体からなる群から選択される１又は２以上と、触媒金属原子とのモル比が3：1～5：1となるように、前記第二工程において重合体と触媒金属塩を混合する、（８）又は（９）に記載の電極触媒の製造方法。 (10) The molar ratio of 1 or 2 or more selected from the group consisting of diaminopyridine, diaminopyridine derivative, triaminopyridine, triaminopyridine derivative, tetraaminopyridine and tetraaminopyridine derivative to the catalytic metal atom is 3: The method for producing an electrode catalyst according to (8) or (9), wherein the polymer and the catalyst metal salt are mixed in the second step so as to be 1 to 5: 1.
（１１）前記触媒金属が２種類以上の異なる金属である、（８）～（１０）のいずれかに記載の電極触媒の製造方法。 (11) The method for producing an electrode catalyst according to any one of (8) to (10), wherein the catalyst metal is two or more different metals.
（１２）前記触媒金属が遷移金属である、（８）～（１１）のいずれかに記載の電極触媒の製造方法。 (12) The method for producing an electrode catalyst according to any one of (8) to (11), wherein the catalyst metal is a transition metal.
（１３）前記第一工程においてジアミノピリジンとジアミノピリジン誘導体の少なくとも一方のモノマーのみを重合させる、（８）～（１２）のいずれかに記載の電極触媒の製造方法。 (13) The method for producing an electrode catalyst according to any one of (8) to (12), wherein in the first step, only at least one monomer of diaminopyridine and a diaminopyridine derivative is polymerized.
（１４）前記ジアミノピリジンが2,6-ジアミノピリジンである、（８）～（１３）のいずれかに記載の電極触媒の製造方法。 (14) The method for producing an electrode catalyst according to any one of (8) to (13), wherein the diaminopyridine is 2,6-diaminopyridine.
（１５）（８）～（１４）のいずれかに記載の製造方法によって得られる電極触媒。 (15) An electrode catalyst obtained by the production method according to any one of (8) to (14).
（１６）（１）～（７）及び（１５）のいずれかに記載の電極触媒を担持する導電性担体を含むガス拡散電極。 (16) A gas diffusion electrode comprising a conductive carrier carrying the electrode catalyst according to any one of (1) to (7) and (15).
（１７）前記導電性担体が炭素系物質である、（１６）に記載のガス拡散電極。 (17) The gas diffusion electrode according to (16), wherein the conductive support is a carbon-based material.
（１８）前記ガス拡散電極が支持体をさらに含む、（１６）又は（１７）に記載のガス拡散電極。 (18) The gas diffusion electrode according to (16) or (17), wherein the gas diffusion electrode further comprises a support.
（１９）（１６）～（１８）のいずれかに記載のガス拡散電極を備えた燃料電池。 (19) A fuel cell comprising the gas diffusion electrode according to any one of (16) to (18).
（２０）燃料電池が固体高分子型燃料電池又は微生物燃料電池である、（１９）に記載の燃料電池。 (20) The fuel cell according to (19), wherein the fuel cell is a polymer electrolyte fuel cell or a microbial fuel cell.
　本明細書は本願の優先権の基礎である日本国特許出願2011-116146号、及び同2011-275678号の明細書及び／又は図面に記載される内容を包含する。 This specification includes the contents described in the specification and / or drawings of Japanese Patent Application Nos. 2011-116146 and 2011-275678, which are the basis of the priority of the present application.
　本発明の電極触媒によれば、現在主流のPt系触媒と同等又はそれよりも高いORR触媒活性、耐久性及び耐食性を有し、かつ低廉な電極触媒を提供することができる。 The electrocatalyst of the present invention can provide an inexpensive electrocatalyst having an ORR catalytic activity, durability and corrosion resistance equivalent to or higher than that of the current mainstream Pt-based catalyst.
　本発明の電極触媒の製造方法によれば、従来の電極触媒と比較して同等又はそれよりも高いORR触媒活性、耐久性及び耐食性を有する電極触媒を低コストで製造することができる。 According to the method for producing an electrocatalyst of the present invention, an electrocatalyst having an ORR catalyst activity, durability, and corrosion resistance equivalent to or higher than that of a conventional electrocatalyst can be produced at a low cost.
　本発明のガス拡散電極によれば、触媒活性能、耐久性能及び耐食性能が高く、かつ低廉で安定的に供給が可能なガス拡散電極を提供することができる。 According to the gas diffusion electrode of the present invention, it is possible to provide a gas diffusion electrode that has high catalytic activity, durability and corrosion resistance, and can be stably supplied at low cost.
　本発明の燃料電池によれば、エネルギー変換効率能が高く、かつ長寿命で低廉な燃料電池を提供することができる。 According to the fuel cell of the present invention, it is possible to provide a fuel cell with high energy conversion efficiency, long life and low cost.
異なる混合比で混合した2,6-ジアミノピリジンポリマーと硝酸コバルトからなる重合体金属錯体を焼成して得られた電極触媒のそれぞれのORR触媒活性を示す。The ORR catalytic activity of each electrode catalyst obtained by calcining a polymer metal complex composed of 2,6-diaminopyridine polymer and cobalt nitrate mixed at different mixing ratios is shown. 電極触媒を備えたRRDE（回転リングディスク電極）によるORR触媒活性の比較を示す図である。RRDEは、CoDAPP（Co-2,6-ジアミノピリジンポリマー）、CoTMPP、CoPPy及びPtの各電極触媒含む。（ａ）はCoDAPP触媒を、（ｂ）はCoTMPP触媒を、（ｃ）はCoPPy触媒を、（ｄ）はPt触媒を、それぞれ示している。It is a figure which shows the comparison of ORR catalyst activity by RRDE (rotating ring disk electrode) provided with the electrode catalyst. RRDE contains CoDAPP (Co-2,6-diaminopyridine polymer), CoTMPP, CoPPy and Pt electrocatalysts. (A) shows a CoDAPP catalyst, (b) shows a CoTMPP catalyst, (c) shows a CoPPy catalyst, and (d) shows a Pt catalyst. 電極触媒としてFeDAPP（Fe-2,6-ジアミノピリジンポリマー）又はCoDAPPをそれぞれ塗布したRRDEによるORR触媒活性の比較を示す図である。（ａ）はFeDAPP触媒の、（ｂ）はCoDAPP触媒の触媒活性を示す。It is a figure which shows the comparison of the ORR catalyst activity by RRDE which apply | coated FeDAPP (Fe-2,6-diaminopyridine polymer) or CoDAPP as an electrode catalyst, respectively. (A) shows the catalytic activity of the FeDAPP catalyst, and (b) shows the catalytic activity of the CoDAPP catalyst. RRDEにおける活性使用回数とCoDAPP触媒の触媒活性の喪失を示す図である。It is a figure which shows the loss of the catalytic activity of the activity use frequency and CoDAPP catalyst in RRDE. 各ガス拡散電極をカソードに用いた時のMFCの電流と電圧の関係曲線を示す。（ａ）はCoDAPP触媒を含むガス拡散電極（CoDAPP電極）を、（ｂ）はCoTMPP触媒を含むガス拡散電極（CoTMPP電極）を、（ｃ）はCoPPy触媒を含むガス拡散電極（CoPPy電極）を、（ｄ）はPt触媒を含むガス拡散電極（Pt電極）を、それぞれ示している。The relationship curve of the current and voltage of MFC when each gas diffusion electrode is used as a cathode is shown. (A) A gas diffusion electrode (CoDAPP electrode) containing a CoDAPP catalyst, (b) a gas diffusion electrode (CoTMPP electrode) containing a CoTMPP catalyst, and (c) a gas diffusion electrode (CoPPy electrode) containing a CoPPy catalyst. , (D) show gas diffusion electrodes (Pt electrodes) each containing a Pt catalyst. 各ガス拡散電極をカソードに用いた時のMFCの出力密度を示す。（ａ）はCoDAPP電極を、（ｂ）はCoTMPP電極を、（ｃ）はCoPPy電極を、（ｄ）はPt電極を、それぞれ示している。The power density of MFC when each gas diffusion electrode is used as a cathode is shown. (A) shows a CoDAPP electrode, (b) shows a CoTMPP electrode, (c) shows a CoPPy electrode, and (d) shows a Pt electrode. 参照極としてAg/AgCl電極を用いて測定した各ガス拡散電極の分極曲線を示す（ａ）及び（ａ’）はCoDAPP電極をカソードに用いた際の、それぞれアノード及びカソードの性能を、（ｂ）及び（ｂ’）はCoTMPP電極をカソードに用いた際の、それぞれアノード及びカソードの性能を、（ｃ）及び（ｃ’）はCoPPy電極をカソードに用いた際の、それぞれアノード及びカソードの性能を、（ｄ）及び（ｄ’）はPt電極をカソードに用いた際の、それぞれアノード及びカソードの性能を、示している。The polarization curves of each gas diffusion electrode measured using an Ag / AgCl electrode as a reference electrode are shown in (a) and (a ′), respectively, when the CoDAPP electrode is used as the cathode, ) And (b ′) show the performance of the anode and the cathode, respectively, when the CoTMPP electrode is used as the cathode, and (c) and (c ′) show the performance of the anode and the cathode, respectively, when the CoPPy electrode is used as the cathode. (D) and (d ′) show the performance of the anode and the cathode, respectively, when the Pt electrode is used as the cathode. （A）CoDAPP電極、（B）CoTMPP電極、及び（C）Pt電極をガス拡散電極としてカソードに用いたときのサイクリックボルタモグラムを示す。The cyclic voltammogram when (A) CoDAPP electrode, (B) CoTMPP electrode, and (C) Pt electrode are used as cathodes as gas diffusion electrodes is shown. 異なる触媒金属を有する電極触媒を備えたRRDEのpH1でのORR触媒活性の比較を示す分極曲線図である。（ａ）はCoDAPP触媒を、（ｂ）はFeDAPP触媒を、（ｃ）はFeとCoを触媒金属として有するFe/CoDAPP（Fe/Co-2,6-ジアミノピリジンポリマー）触媒をそれぞれ示している。It is a polarization curve figure which shows the comparison of the ORR catalyst activity in pH1 of RRDE provided with the electrocatalyst which has a different catalyst metal. (A) shows a CoDAPP catalyst, (b) shows an FeDAPP catalyst, (c) shows an Fe / CoDAPP (Fe / Co-2,6-diaminopyridine polymer) catalyst having Fe and Co as catalytic metals, respectively. . 異なる触媒金属を有する電極触媒を備えたRRDEのpH7でのORR触媒活性の比較を示す分極曲線図である。（ａ）はCoDAPP触媒を、（ｂ）はFeDAPP触媒を、（ｃ）はFe/CoDAPP触媒を、それぞれ示している。FIG. 6 is a polarization curve diagram showing a comparison of ORR catalytic activity at pH 7 of RRDE equipped with electrocatalysts having different catalytic metals. (A) shows the CoDAPP catalyst, (b) shows the FeDAPP catalyst, and (c) shows the Fe / CoDAPP catalyst. 異なる触媒金属を有する電極触媒を備えたRRDEのpH13でのORR触媒活性の比較を示す分極曲線図である。（ａ）はCoDAPP触媒を、（ｂ）はFeDAPP触媒を、（ｃ）はFe/CoDAPP触媒を、それぞれ示している。It is a polarization curve figure which shows the comparison of the ORR catalyst activity in pH13 of RRDE provided with the electrocatalyst which has a different catalyst metal. (A) shows the CoDAPP catalyst, (b) shows the FeDAPP catalyst, and (c) shows the Fe / CoDAPP catalyst. 窒素BET吸着法等によるCoDAPP電極（A）とPt電極（B）の測定結果を示す図である。It is a figure which shows the measurement result of the CoDAPP electrode (A) and Pt electrode (B) by nitrogen BET adsorption method etc.
１．電極触媒
１－１．概要
　本発明の第１の実施形態は、電極触媒である。本発明の電極触媒は、特定の金属錯体を触媒成分とし、Pt系触媒等の従来の電極触媒と比較して同等又はより高いORR触媒活性、耐久性及び耐食性を有することを特徴とする。 1. Electrode catalyst 1-1. Outline | summary The 1st Embodiment of this invention is an electrode catalyst. The electrode catalyst of the present invention is characterized by having a specific metal complex as a catalyst component and having the same or higher ORR catalyst activity, durability and corrosion resistance as compared with conventional electrode catalysts such as Pt-based catalysts.
１－２．構成
　本発明の電極触媒は、触媒成分として、１）特定の物性を有する金属錯体、又は２）特定の重合体金属錯体を焼成処理して成る金属錯体を含む。以下で本発明の電極触媒の構成について具体的に説明をする。 1-2. Structure The electrode catalyst of the present invention contains, as a catalyst component, 1) a metal complex having specific physical properties, or 2) a metal complex formed by firing a specific polymer metal complex. The configuration of the electrode catalyst of the present invention will be specifically described below.
　本発明において「金属錯体」とは、重合体及び／又はその変性物、並びに触媒金属からなり、該重合体又はその変性物中の配位子が該触媒金属と配位結合した化合物をいう。 In the present invention, the “metal complex” refers to a compound comprising a polymer and / or a modified product thereof and a catalytic metal, wherein a ligand in the polymer or the modified product is coordinated with the catalytic metal.
　本明細書において「焼成金属錯体」とは、重合体金属錯体を焼成処理した化合物をいう。ここでいう「焼成（処理）」とは、高温での熱処理をいう。 In the present specification, “fired metal complex” refers to a compound obtained by firing a polymer metal complex. “Baking (treatment)” here refers to a heat treatment at a high temperature.
　本明細書において、「重合体金属錯体」とは、焼成処理を行っていない状態の前記金属錯体をいう。 In the present specification, the “polymer metal complex” refers to the metal complex in a state where no baking treatment is performed.
　以下、本明細書において単に「金属錯体」と表記した場合には、焼成処理済みであるか否かにかかわらず、前記焼成金属錯体及び重合体金属錯体を包括的に指すものとする。 Hereinafter, when simply expressed as “metal complex” in the present specification, the fired metal complex and the polymer metal complex are comprehensively referred to regardless of whether or not the firing treatment has been completed.
　本発明の電極触媒において、触媒成分として機能する必須の構成要素は、後述するように、特定の重合体及び／又はその変性物、並びに触媒金属とからなる金属錯体、又は特定の重合体と触媒金属とからなる金属錯体を焼成してなる焼成金属錯体である。以下、本発明の電極触媒において必須の構成要素となるこれらの金属錯体を、総括して、「2-4アミノピリジンポリマー金属錯体」と称する。 In the electrode catalyst of the present invention, the essential component functioning as a catalyst component is, as will be described later, a specific polymer and / or a modified product thereof, and a metal complex composed of a catalytic metal, or a specific polymer and a catalyst. A fired metal complex obtained by firing a metal complex composed of a metal. Hereinafter, these metal complexes that are essential components in the electrode catalyst of the present invention are collectively referred to as “2-4 aminopyridine polymer metal complexes”.
　本発明において、「2-4アミノピリジンポリマー」とは、モノマーであるジアミノピリジン（C5H7N3）、ジアミノピリジン誘導体、トリアミノピリジン（C5H8N4）、トリアミノピリジン誘導体、テトラアミノピリジン（C5H9N5）及びテトラアミノピリジン誘導体からなる群から選択される１又は２以上が重合した化合物の総括名称である。本明細書において単に「重合体（ポリマー）」と表記した場合には、特に断りのない限り、「2-4アミノピリジンポリマー」を指すものとする。また、「その変性物」とは、前記重合体の変性物であり、これは、重合体金属錯体を焼成したときに、重合体の熱分解等により生じる化合物及びオリゴマー等を指す。 In the present invention, “2-4 aminopyridine polymer” means a monomer diaminopyridine (C 5 H 7 N 3 ), diaminopyridine derivative, triaminopyridine (C 5 H 8 N 4 ), triaminopyridine derivative, It is a general name for compounds in which one or more selected from the group consisting of tetraaminopyridine (C 5 H 9 N 5 ) and tetraaminopyridine derivatives are polymerized. In the present specification, the term “polymer” means “2-4 aminopyridine polymer” unless otherwise specified. Further, the “modified product” is a modified product of the polymer, and refers to a compound, an oligomer, and the like generated by thermal decomposition of the polymer when the polymer metal complex is baked.
　前記ジアミノピリジン、トリアミノピリジン及びテトラアミノピリジンは、ピリジン（C5H5N）の水素原子（H）がそれぞれ2つ、3つ及び4つのアミノ基（-NH2）と置換した化合物である。2-4アミノピリジンポリマーを構成するモノマーは、1種のみ又は2種以上の組合せのいずれで構成されていてもよい。 The diaminopyridine, triaminopyridine and tetraaminopyridine are compounds in which the hydrogen atom (H) of pyridine (C 5 H 5 N) is substituted with 2 , 3 and 4 amino groups (—NH 2 ), respectively. . The monomer constituting the 2-4 aminopyridine polymer may be composed of only one kind or a combination of two or more kinds.
　ジアミノピリジンには、2, 3-ジアミノピリジン、2, 4-ジアミノピリジン、2, 5-ジアミノピリジン、2, 6-ジアミノピリジン及び3, 4-ジアミノピリジンの位置異性体が、トリアミノピリジンには、2, 3, 4-トリアミノピリジン、2, 3, 5-トリアミノピリジン、2, 3, 6-トリアミノピリジン、2, 4, 5-トリアミノピリジン、2, 4, 6-トリアミノピリジン及び3, 4, 5-トリアミノピリジンの位置異性体が、またテトラアミノピリジンには、2, 3, 4, 5-テトラアミノピリジン、2, 4, 5, 6-テトラアミノピリジン及び2, 3, 5, 6-テトラアミノピリジンの位置異性体が知られているが、2-4アミノピリジンポリマーを構成する各モノマーは、いずれの位置異性体であってもよい。また、同一の位置異性体のみで構成されていてもよいし、異なる2種以上の位置異性体で構成されていてもよい。 Diaminopyridine has positional isomers of 2, 3-diaminopyridine, 2, 4-diaminopyridine, 2, 5-diaminopyridine, 2, 6-diaminopyridine and 3, 4-diaminopyridine, and triaminopyridine has 2, 3, 4-triaminopyridine, 2, 3, 5-triaminopyridine, 2, 3, 6-triaminopyridine, 2, 4, 5-triaminopyridine, 2, 4, 6-triaminopyridine And 3, 4, 5-triaminopyridine, and tetraaminopyridine includes 2, 3, 4, 5-tetraaminopyridine, 2, 4, 5, 6-tetraaminopyridine and 2, 3 , 5, 6-tetraaminopyridine positional isomers are known, but each monomer constituting the 2-4 aminopyridine polymer may be any positional isomer. Moreover, it may be composed only of the same positional isomers, or may be composed of two or more different positional isomers.
　また、ジアミノピリジンの誘導体には、例えば、4メチル-2, 6-ジアミノピリジン、4エチル-2, 6-ジアミノピリジン及び3メチル-2, 6-ジアミノピリジンが挙げられる。 In addition, examples of the derivatives of diaminopyridine include 4 methyl-2, 6-diaminopyridine, 4 ethyl-2, 6-diaminopyridine and 3methyl-2, 6-diaminopyridine.
　トリアミノピリジンの誘導体には、例えば、3メチル-2, 3, 6-トリアミノピリジン及び3エチル-2, 3, 6-トリアミノピリジンが挙げられる。 Examples of the derivative of triaminopyridine include 3methyl-2, 3, 6-triaminopyridine and 3ethyl-2, 3, 6-triaminopyridine.
　テトラアミノピリジンの誘導体には、例えば、4Nメチルアミノ-2, 3, 6-トリアミノピリジン、4Nメチルアミノ-2, 4, 6-トリアミノピリジン及び4N,Nジアミノ-2, 3, 6-トリアミノピリジンが挙げられる。 Tetraaminopyridine derivatives include, for example, 4N methylamino-2, 3, 6-triaminopyridine, 4N methylamino-2, 4, 6-triaminopyridine and 4N, N diamino-2, 3, 6-triaminopyridine. Aminopyridine is mentioned.
　2-4アミノピリジンポリマーが2種以上のモノマー及び／又は2種以上の位置異性体で構成される場合、2-4アミノピリジンポリマー中のそれぞれのモノマー及び／又は位置異性体の配置は、重合可能な限り、特に限定はしない。例えば、特定のモノマーの組合せが規則的に繰り返されるように重合されていてもよいし、ランダムに重合されていてもよい。 When the 2-4 aminopyridine polymer is composed of two or more types of monomers and / or two or more types of positional isomers, the arrangement of the respective monomers and / or positional isomers in the 2-4 aminopyridine polymer is a polymerization. There is no particular limitation as much as possible. For example, it may be polymerized so that a combination of specific monomers is regularly repeated, or may be polymerized randomly.
　前記重合体金属錯体は、2-4アミノピリジンポリマーが包含する配位子が触媒金属を配位している。当該ポリマーにおいて配位子となり得る原子（配位原子）には、例えば、ピリジン環の窒素原子及び／又はアミノ基の窒素原子等が挙げられる。ここで、ジアミノピリジンとその誘導体、トリアミノピリジンとその誘導体及びテトラアミノピリジンとその誘導体は、配位子となり得る窒素原子を一分子内に、それぞれ3つ、4つ及び5つ包含している。したがって、これらのモノマーからなる2-4アミノピリジンポリマーは、窒素原子の含有量が多くなる。また構造面では、触媒金属と配位結合し得る窒素原子を含む配位子となる分子又はモノマーの寸法が小さいため、配位結合し得る窒素原子の数が多い。それ故に、窒素／炭素比と触媒金属／窒素比の双方が大きな値をとることの両立が可能となる。この特徴により、本発明の電極触媒は、高いORR触媒活性を有し得る。 In the polymer metal complex, the ligand included in the 2-4 aminopyridine polymer coordinates the catalyst metal. Examples of the atom (coordinating atom) that can be a ligand in the polymer include a nitrogen atom of a pyridine ring and / or a nitrogen atom of an amino group. Here, diaminopyridine and derivatives thereof, triaminopyridine and derivatives thereof, and tetraaminopyridine and derivatives thereof include three, four, and five nitrogen atoms, respectively, that can be ligands. . Therefore, the 2-4 aminopyridine polymer composed of these monomers has a high nitrogen atom content. In terms of the structure, since the size of the molecule or monomer serving as a ligand containing a nitrogen atom capable of coordinating with the catalyst metal is small, the number of nitrogen atoms capable of coordinating bonding is large. Therefore, both of the nitrogen / carbon ratio and the catalytic metal / nitrogen ratio can be both large. Due to this feature, the electrocatalyst of the present invention can have high ORR catalytic activity.
　2-4アミノピリジンポリマーの好ましい一例として、ジアミノピリジンのみが重合した「ジアミノピリジンポリマー」が挙げられる。ジアミノピリジンポリマーを構成する位置異性体は、限定はしないが、2,6-ジアミノピリジン及び／又は2,3-ジアミノピリジンが好ましい。これらの位置異性体は、分子内で窒素原子（N）が互いに最も近位に配置されるため、重合体中で触媒金属をより安定して配位することができるためである。より好ましいジアミノピリジンポリマーは、2,6-ジアミノピリジンモノマーのみが重合した2,6-ジアミノピリジンポリマーである。 As a preferred example of the 2-4 aminopyridine polymer, “diaminopyridine polymer” in which only diaminopyridine is polymerized can be mentioned. The positional isomer constituting the diaminopyridine polymer is not limited, but 2,6-diaminopyridine and / or 2,3-diaminopyridine are preferable. These positional isomers are because the nitrogen atoms (N) are arranged closest to each other in the molecule, so that the catalytic metal can be coordinated more stably in the polymer. A more preferred diaminopyridine polymer is a 2,6-diaminopyridine polymer in which only 2,6-diaminopyridine monomer is polymerized.
　2-4アミノピリジンポリマーを構成する各モノマーを連結する化学重合反応は、限定はしないが、好ましくはアニオン重合である。重合体が2,6-ジアミノピリジンポリマーである場合、そのポリマーは、2,6-ジアミノピリジンのアニオン重合により、例えば、以下の式（Ｉ）及び／又は（ＩＩ）で示す化学構造を含むことが予想される。
Figure JPOXMLDOC01-appb-C000001
Figure JPOXMLDOC01-appb-C000002
 The chemical polymerization reaction for linking the monomers constituting the 2-4 aminopyridine polymer is not limited, but is preferably anionic polymerization. When the polymer is a 2,6-diaminopyridine polymer, the polymer contains, for example, a chemical structure represented by the following formula (I) and / or (II) by anionic polymerization of 2,6-diaminopyridine. Is expected.
Figure JPOXMLDOC01-appb-C000001
Figure JPOXMLDOC01-appb-C000002
　本明細書において「触媒金属」とは、金属錯体中に配位された金属原子又は金属イオンである。触媒金属は、特に制限はしないが、好ましくは遷移金属である。具体的には、例えば、チタン（Ti）、バナジウム（V）、クロム（Cr）、マンガン（Mn）、鉄（Fe）、コバルト（Co）、ニッケル（Ni）、銅（Cu）、ジルコニウム（Zr）、ニオブ（Nb）、モリブデン（Mo）、ルテニウム（Ru）、ロジウム（Rh）、パラジウム（Pd）、銀（Ag）、ハフニウム（Hf）、タンタル（Ta）、タングステン（W）、レニウム（Re）、オスニウム（Os）、イリジウム（Ir）、Pt及び金（Au）等の原子又はそのイオンが挙げられる。当業者は、これらの触媒金属からコスト、供給量、触媒活性効率等を勘案し、目的に応じて適切な触媒金属を適宜選択すればよい。本発明の電極触媒において、触媒金属としては、Cr、Mn、Fe、Co、Ni及びCuが好適である。金属錯体は、１種類の触媒金属を配位していてもよいし、又は異なる二以上の触媒金属を配位していてもよい。例えば、FeとCoを配位した金属錯体が挙げられる。なお、Pt及びAuは希少かつ高価であることから、本発明の目的に反するかに思われるが、金属錯体中に配位させて用いることで、公知のPt系触媒と比較してPt使用量を相対的に低減することが可能であることから、本発明の目的を達し得る。それ故、本発明における触媒金属に包含することができる。 In the present specification, the “catalytic metal” is a metal atom or metal ion coordinated in a metal complex. The catalyst metal is not particularly limited, but is preferably a transition metal. Specifically, for example, titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr ), Niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re ), Osnium (Os), iridium (Ir), Pt, gold (Au), and the like or ions thereof. Those skilled in the art may appropriately select an appropriate catalyst metal according to the purpose in consideration of cost, supply amount, catalyst activity efficiency, and the like from these catalyst metals. In the electrode catalyst of the present invention, the catalyst metal is preferably Cr, Mn, Fe, Co, Ni, and Cu. The metal complex may coordinate one type of catalyst metal, or may coordinate two or more different catalyst metals. An example is a metal complex in which Fe and Co are coordinated. Although Pt and Au are rare and expensive, it seems to be contrary to the purpose of the present invention, but by using them coordinated in a metal complex, the amount of Pt used compared to known Pt-based catalysts Therefore, the object of the present invention can be achieved. Therefore, it can be included in the catalyst metal in the present invention.
　2-4アミノピリジンポリマー金属錯体の構造例として、2,6-ジアミノピリジンポリマーが触媒金属としてコバルトを配位した金属錯体（Co-2,6-ジアミノピリジンポリマー；Co-2,6-diaminopyridinepolymer、本明細書では、しばしば「CoDAPP」で表す）の場合には、例えば、以下の式（ＩＩＩ）で示す構造を含むことが予想される。
Figure JPOXMLDOC01-appb-C000003
 As an example of the structure of a 2-4 aminopyridine polymer metal complex, a 2,6-diaminopyridine polymer is a metal complex in which cobalt is coordinated as a catalytic metal (Co-2,6-diaminopyridine polymer; Co-2,6-diaminopyridine polymer, In the present specification, it is expected to include, for example, a structure represented by the following formula (III) in the case of “CoDAPP”.
Figure JPOXMLDOC01-appb-C000003
　式中、Meは、触媒金属（本例では、Co）を表す。 In the formula, Me represents a catalyst metal (Co in this example).
　本発明の2-4アミノピリジンポリマー金属錯体は、好ましくは重合体金属錯体を焼成処理して得られる。焼成処理によって重合体金属錯体中の触媒金属が安定して窒素原子に配位され、その結果、化学的硬化により、安定した触媒活性能と高い耐久性及び耐食性を得ることができるからである。 The 2-4 aminopyridine polymer metal complex of the present invention is preferably obtained by baking a polymer metal complex. This is because the catalyst metal in the polymer metal complex is stably coordinated to the nitrogen atom by the calcination treatment, and as a result, stable catalytic activity, high durability, and corrosion resistance can be obtained by chemical curing.
　2-4アミノピリジンポリマー金属錯体における2-4アミノピリジンポリマーと触媒金属塩の混合比は、原料モノマーと触媒金属原子とのモル比で3：１～5：1、好ましくは3.5：1～4.5：1となるように選択すればよい。二以上の異なる触媒金属を用いる場合であっても、原料モノマーと全触媒金属原子のモル比が上記範囲内になるようにすればよい。異なる触媒金属間のモル比は、特に限定はしない。使用する触媒金属の種類等に応じて適宜定めればよい。例えば、CoとFeを使用する場合には、CoとFeのモル比が1:0.1～1:10の範囲内となるように選択すればよい。 The mixing ratio of the 2-4 aminopyridine polymer to the catalyst metal salt in the 2-4 aminopyridine polymer metal complex is 3: 1 to 5: 1, preferably 3.5: 1 to 4.5, as the molar ratio of the raw material monomer to the catalyst metal atom. : Select to be 1. Even when two or more different catalyst metals are used, the molar ratio of the raw material monomers to the total catalyst metal atoms may be within the above range. The molar ratio between different catalytic metals is not particularly limited. What is necessary is just to determine suitably according to the kind etc. of the catalyst metal to be used. For example, when using Co and Fe, the molar ratio of Co and Fe may be selected within a range of 1: 0.1 to 1:10.
　焼成処理のための「焼成温度」は、650～800℃、好ましくは680～780℃、より好ましくは690～760℃、さらに好ましくは700～750℃である。焼成処理は、電極触媒を熱処理するための公知の方法で行い得る。本発明では、炭素が窒素ドープされていることが必要である。例えば、乾燥した重合体金属錯体の粉末を還元性ガス雰囲気下又は不活性ガス雰囲気下において前記焼成温度で、30分間～5時間、好ましくは1時間～2時間焼成すればよい。好ましくは、還元性ガス雰囲気下での焼成である。還元性ガスは、例えば、アンモニアを使用することができる。不活性ガスは、例えば、窒素を使用することができる。不活性ガス雰囲気下で焼成する場合、一般に、炭素材料を不活性ガス雰囲気下で焼成するのみでは窒素ドープはされない。しかし、本発明では、窒素を含む2-4アミノピリジンポリマーを炭素材料として使用することから不活性ガス雰囲気下での焼成でも目的を達成し得る。不活性ガス雰囲気下で焼成する場合には、その後、さらに還元性ガス雰囲気下で焼成してもよい。 The “calcination temperature” for the calcination treatment is 650 to 800 ° C., preferably 680 to 780 ° C., more preferably 690 to 760 ° C., further preferably 700 to 750 ° C. The firing treatment can be performed by a known method for heat-treating the electrode catalyst. In the present invention, it is necessary that carbon is nitrogen-doped. For example, the dried polymer metal complex powder may be calcined at a calcining temperature for 30 minutes to 5 hours, preferably 1 hour to 2 hours in a reducing gas atmosphere or an inert gas atmosphere. Preferably, the firing is performed in a reducing gas atmosphere. For example, ammonia can be used as the reducing gas. As the inert gas, for example, nitrogen can be used. When firing in an inert gas atmosphere, nitrogen doping is generally not performed only by firing the carbon material in an inert gas atmosphere. However, in the present invention, since a 2-4 aminopyridine polymer containing nitrogen is used as the carbon material, the object can be achieved even by firing in an inert gas atmosphere. In the case of firing in an inert gas atmosphere, it may be further fired in a reducing gas atmosphere.
　「特定の物性」とは、本発明における2-4アミノピリジンポリマー金属錯体が示す物理的性質であって、例えば、前記重合体金属錯体を焼成することにより、重合体金属錯体において触媒金属の窒素原子への配位が安定する結果として得られる下記（i）～（iii）の少なくとも一つを満たす性質をいう。 The “specific physical properties” are physical properties exhibited by the 2-4 aminopyridine polymer metal complex in the present invention. For example, by firing the polymer metal complex, the catalyst metal nitrogen in the polymer metal complex A property that satisfies at least one of the following (i) to (iii) obtained as a result of stabilization of coordination to an atom.
（i）窒素(N)／炭素（C）の元素比が、モル比で0.11以上である
（ii）触媒金属（Metal）／窒素（N）の元素比が、モル比で0.03以上、好ましくは0.05以上である（iii）窒素原子に配位した触媒金属の含有率が0.4モル％以上であり、かつ、窒素原子の含有率が6.0モル％以上である。 (I) Element ratio of nitrogen (N) / carbon (C) is 0.11 or more in molar ratio (ii) Element ratio of catalyst metal (Metal) / nitrogen (N) is 0.03 or more in molar ratio, preferably (Iii) The content of the catalyst metal coordinated to the nitrogen atom is 0.05 or more and 0.4 mol% or more, and the content of the nitrogen atom is 6.0 mol% or more.
　上記、電極触媒における炭素、窒素及び窒素原子に配位した触媒金属の各含有率は、X線光電子分光分析により測定される。含有率はいずれも、金属錯体を基準としたときの（金属錯体を100モル％としたときの）それらの割合である。 Each content of the catalyst metal coordinated to carbon, nitrogen, and nitrogen atom in the electrode catalyst is measured by X-ray photoelectron spectroscopy. All the content rates are their ratios when the metal complex is used as a reference (when the metal complex is 100 mol%).
　焼成により、2-4アミノピリジンポリマーの一部が変性することがあり、重合体の形態が失われることがある。そのような変性は、焼成金属錯体が電極触媒として使用され得る限りにおいて、許容され、したがって、本発明の電極触媒を構成する2-4アミノピリジンポリマー金属錯体は、2-4アミノピリジンポリマーが焼成により変性した物質を含み得る。 Calcination may cause a part of the 2-4 aminopyridine polymer to be modified, and the polymer form may be lost. Such modification is permissible as long as the calcined metal complex can be used as an electrocatalyst, and therefore the 2-4 aminopyridine polymer metal complex constituting the electrocatalyst of the present invention is calcined with 2-4 aminopyridine polymer. May contain a modified material.
　焼成金属錯体の形状は、特に限定はしない。しかし、電極表面に担持させる電極触媒の単位面積当たりの比表面積は、大きい方が好ましい。電極の単位質量当たりの触媒活性（質量活性）をより高めることができるからである。したがって、好ましい形状は、粒子状、特に粉末状である。焼成金属錯体の比表面積は、好ましくは500m2／g以上であり、より好ましくは550m2／g以上である。このような比表面積は、窒素BET吸着法等によって測定することができる。また、電極触媒の導電率は、0.1s/cm～10s/cmの範囲内にあることが好ましい。 The shape of the fired metal complex is not particularly limited. However, it is preferable that the specific surface area per unit area of the electrode catalyst supported on the electrode surface is large. This is because the catalytic activity (mass activity) per unit mass of the electrode can be further increased. Therefore, a preferable shape is a particle shape, particularly a powder shape. The specific surface area of the calcined metal complex is preferably 500 m 2 / g or more, more preferably 550 m 2 / g or more. Such a specific surface area can be measured by a nitrogen BET adsorption method or the like. The conductivity of the electrode catalyst is preferably in the range of 0.1 s / cm to 10 s / cm.
　本発明の電極触媒は、上記焼成金属錯体以外の触媒成分を含むことができる。例えば、CoTMPP触媒のような公知の触媒を含んでいてもよい。 The electrode catalyst of the present invention can contain a catalyst component other than the calcined metal complex. For example, a known catalyst such as a CoTMPP catalyst may be included.
１－３．効果
　本発明によれば、従来のポリマーと触媒金属を含む金属錯体由来の電極触媒よりも、より多くの触媒金属を配位することができる。それによってPt系触媒やCoTMPP触媒のような公知の電極触媒と比較して、同等又はより高いORR触媒活性と耐久性を有し、かつPtを使用しない若しくはその使用量を低減できる。 1-3. Effect According to the present invention, more catalytic metal can be coordinated than an electrode catalyst derived from a metal complex containing a conventional polymer and catalytic metal. As a result, compared with known electrocatalysts such as Pt-based catalysts and CoTMPP catalysts, it has equivalent or higher ORR catalytic activity and durability, and Pt is not used or the amount thereof can be reduced.
　また、Ptに代えてFe等の安価な金属を触媒金属として利用できることから、単位質量あたりの製造コストが低廉な電極触媒を提供することができ、さらに将来的な燃料電池の量産化に伴う資源供給量の増大にも対応することできる。 In addition, since an inexpensive metal such as Fe can be used as the catalyst metal instead of Pt, it is possible to provide an electrode catalyst with a low manufacturing cost per unit mass, and further, resources accompanying mass production of fuel cells in the future It is possible to cope with an increase in supply amount.
２．電極触媒の製造方法
２－１．概要
　本発明の第２の実施形態は、電極触媒の製造方法である。本製造方法は、第１実施形態に記載したような電極触媒を低廉で製造することができる。 2. 2. Production method of electrode catalyst 2-1. Outline | summary The 2nd Embodiment of this invention is a manufacturing method of an electrode catalyst. This manufacturing method can manufacture the electrode catalyst as described in the first embodiment at a low cost.
２－２．方法
　本発明の製造方法は、（ａ）重合工程、（ｂ）重合体金属錯体形成工程及び（ｃ）焼成工程を含む。以下、それぞれの工程について、具体的に説明をする。 2-2. Method The production method of the present invention includes (a) a polymerization step, (b) a polymer metal complex formation step, and (c) a firing step. Hereinafter, each process will be specifically described.
（ａ）重合工程
　「重合工程」とは、ジアミノピリジン、トリアミノピリジン及び／又はテトラアミノピリジンをアニオン重合させて、2-4アミノピリジンポリマーを合成する工程である。重合させるモノマーは、1種のみを用いてもよいし、又は2又は3種を組み合わせてもよい。2種以上のモノマーを組み合わせて重合させる場合、それぞれのモノマーの混合モル比に特に制限はない。当業者が触媒活性を勘案しつつ適宜定めればよい。重合工程に使用する好ましいモノマーの一例として、ジアミノピリジン単独の場合が挙げられる。 (A) Polymerization Step The “polymerization step” is a step of synthesizing a 2-4 aminopyridine polymer by anionic polymerization of diaminopyridine, triaminopyridine and / or tetraaminopyridine. As the monomer to be polymerized, only one kind may be used, or two or three kinds may be combined. When polymerizing two or more monomers in combination, there is no particular limitation on the mixing molar ratio of each monomer. Those skilled in the art may appropriately determine the catalytic activity. An example of a preferred monomer used in the polymerization step is the case of diaminopyridine alone.
　重合に使用する各モノマーの位置異性体は、特に制限はしないが、好ましくはモノマー分子内で配位子となる窒素原子が近位に位置する位置異性体が好ましい。例えば、前述のジアミノピリジンをモノマーとして重合させる場合には、ジアミノピリジンの位置異性体の中でも窒素原子が最も近位に位置する、2,3-ジアミノピリジン又は2,6-ジアミノピリジンが好ましい。 The positional isomer of each monomer used for polymerization is not particularly limited, but preferably a positional isomer in which a nitrogen atom serving as a ligand in the monomer molecule is located proximally. For example, when the above diaminopyridine is polymerized as a monomer, 2,3-diaminopyridine or 2,6-diaminopyridine in which the nitrogen atom is most proximal among the positional isomers of diaminopyridine is preferable.
　本工程において、上記モノマーは、アニオン重合反応によって重合される。アニオン重合反応は、当該分野で慣用される公知の方法を用いて行えばよい。例えば、上記モノマーに強塩基溶液を作用させて脱プロトン化し、発生したカルバニオンを求核剤として各モノマーを重合させればよい。強塩基溶液に使用する塩基には、例えば、水酸化ナトリウム、水酸化カリウム、水酸化リチウム、水酸化カルシウム等を用いることができる。重合温度や重合時間は、反応が進行する範囲であれば特に限定はしない。通常は、5～40℃の温度下で5～48時間程度反応させれば本工程を達成し得る。 In this step, the monomer is polymerized by an anionic polymerization reaction. The anionic polymerization reaction may be performed using a known method commonly used in the art. For example, a strong base solution is allowed to act on the monomer to deprotonate it, and each monomer is polymerized using the generated carbanion as a nucleophile. As the base used in the strong base solution, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide and the like can be used. The polymerization temperature and polymerization time are not particularly limited as long as the reaction proceeds. Usually, this step can be achieved by reacting at a temperature of 5 to 40 ° C. for about 5 to 48 hours.
　重合反応後は、遠心又はろ過によって溶媒を除去し、重合体を回収する。回収した2-4アミノピリジンポリマーは、水（脱イオン水、蒸留水を含む）等で洗浄した後に乾燥させて、以降の工程に使用することが好ましい。 After the polymerization reaction, the solvent is removed by centrifugation or filtration, and the polymer is recovered. The recovered 2-4 aminopyridine polymer is preferably washed with water (including deionized water and distilled water) and then dried and used in the subsequent steps.
　なお、既に合成された2-4アミノピリジンポリマーを本発明の製造方法で用いる場合には、本工程を経ずに、次の重合体金属錯体形成工程から開始することができる。 When a 2-4 aminopyridine polymer that has already been synthesized is used in the production method of the present invention, the following polymer metal complex formation step can be started without passing through this step.
（ｂ）重合体金属錯体形成工程
　「重合体金属錯体形成工程」とは、2-4アミノピリジンポリマーと触媒金属塩の混合により該ポリマーに触媒金属を配位させて重合体金属錯体を形成させる工程である。2-4アミノピリジンポリマーが包含する窒素原子が配位子（配位原子）となって触媒金属と配位結合し、重合体金属錯体が形成される。 (B) Polymer metal complex formation step "Polymer metal complex formation step" refers to the formation of a polymer metal complex by coordinating a catalyst metal to the polymer by mixing a 2-4 aminopyridine polymer and a catalyst metal salt. It is a process. The nitrogen atom contained in the 2-4 aminopyridine polymer becomes a ligand (coordinating atom) and coordinates with the catalytic metal to form a polymer metal complex.
　「触媒金属塩」は、金属錯体中に配位させる触媒金属の塩であって、具体的には触媒金属の塩酸塩、硫酸塩、硝酸塩、リン酸塩、酢酸塩等が挙げられる。本工程における触媒金属は、電極触媒において触媒活性を有する金属であればよく、特に制限はしないが、好ましくは遷移金属である。具体的には、例えば、前記第１実施形態に記載の遷移金属が挙げられる。このうちCr、Mn、Fe、Co、Ni及びCuの塩は、本工程の触媒金属塩として好適であり、Fe又はCoの触媒金属塩は、特に好ましい。具体的には、塩化鉄、硝酸鉄、硫化鉄、硝酸コバルト、塩化コバルト、硫化コバルト等が挙げられる。 “Catalytic metal salt” is a salt of a catalytic metal to be coordinated in a metal complex, and specifically includes a catalytic metal hydrochloride, sulfate, nitrate, phosphate, acetate, and the like. The catalyst metal in this step is not particularly limited as long as it is a metal having catalytic activity in the electrode catalyst, but is preferably a transition metal. Specifically, for example, the transition metals described in the first embodiment can be mentioned. Among these, salts of Cr, Mn, Fe, Co, Ni and Cu are suitable as the catalyst metal salt in this step, and a catalyst metal salt of Fe or Co is particularly preferable. Specific examples include iron chloride, iron nitrate, iron sulfide, cobalt nitrate, cobalt chloride, and cobalt sulfide.
　2-4アミノピリジンポリマーと触媒金属塩の混合比は、原料モノマーと触媒金属原子のモル比が3：１～5：1、好ましくは3.5：1～4.5：1となるように、選択すれよい。すなわち、（ポリマーを構成する繰り返し単位のモル数）：（触媒金属塩に含まれる金属のモル数）が上記好ましい範囲となるように、ポリマー及び触媒金属塩の質量を選択して、ポリマーと触媒金属塩を混合すればよい。これらを適当な溶媒中で混合して懸濁させ、さらに十分に撹拌することで触媒金属又はそのイオンを2-4アミノピリジンポリマー中に配位させることができる。媒体は、水、エタノール、プロパノール又はそれらを組み合わせた混合溶液、例えば、水とエタノール若しくは水と（イソ）プロパノールの混合溶液等を用いることができる。混合温度や混合時間は、反応が進行する範囲であれば特に限定はしない。通常は、50～70℃の温度下で30分～5時間程度反応さえれば本工程を達成し得る。前記2つの物質を十分に混合させるため、超音波混合を行ってもよい。 The mixing ratio of the 2-4 aminopyridine polymer and the catalytic metal salt may be selected so that the molar ratio of the raw material monomer to the catalytic metal atom is 3: 1 to 5: 1, preferably 3.5: 1 to 4.5: 1. . That is, the mass of the polymer and the catalyst metal salt is selected so that (the number of moles of the repeating unit constituting the polymer) :( the number of moles of the metal contained in the catalyst metal salt) is within the above preferable range. What is necessary is just to mix a metal salt. The catalyst metal or its ion can be coordinated in the 2-4 aminopyridine polymer by mixing and suspending these in a suitable solvent and further stirring sufficiently. As the medium, water, ethanol, propanol or a mixed solution thereof, for example, water and ethanol or a mixed solution of water and (iso) propanol can be used. The mixing temperature and mixing time are not particularly limited as long as the reaction proceeds. Usually, this reaction can be achieved by reaction at a temperature of 50 to 70 ° C. for about 30 minutes to 5 hours. Ultrasonic mixing may be performed in order to sufficiently mix the two substances.
　反応が進行すると、形成された重合体金属錯体は溶媒中において固体となって沈澱する。 As the reaction proceeds, the formed polymer metal complex precipitates as a solid in the solvent.
　重合体金属錯体形成後は、溶媒を遠心、ろ過又は蒸発によって除去して、目的の重合体金属錯体を回収する。未配位の触媒金属等を除くため水（脱イオン水、蒸留水を含む）等で洗浄してもよい。回収された重合体金属錯体は、必要に応じて、例えば、水晶乳鉢（quartz mortar）等を用いて粉末化してもよい。 After the formation of the polymer metal complex, the solvent is removed by centrifugation, filtration or evaporation, and the target polymer metal complex is recovered. In order to remove uncoordinated catalyst metal, etc., it may be washed with water (including deionized water and distilled water). The recovered polymer metal complex may be pulverized as necessary using, for example, a quartz mortar.
（ｃ）焼成工程
　「焼成工程」とは、前記重合体金属錯体形成工程で得られた重合体金属錯体を還元性ガス雰囲気下又は不活性ガス雰囲気下で高温にて焼成し、焼成金属錯体を得る工程である。本工程により重合体金属錯体において触媒金属が移動することによって、触媒金属を安定的に配位した耐久性の高い電極活性成分が調製される。 (C) Firing step The “firing step” refers to firing the polymer metal complex obtained in the polymer metal complex forming step at a high temperature in a reducing gas atmosphere or an inert gas atmosphere. It is a process to obtain. By this step, the catalyst metal moves in the polymer metal complex, whereby a highly durable electrode active component in which the catalyst metal is stably coordinated is prepared.
　焼成温度は、650～800℃、好ましくは680～780℃、より好ましくは690～760℃、さらに好ましくは700～750℃である。この温度で焼成することで、ORR触媒活性及び耐久性の高い触媒成分としての焼成金属錯体を得ることができる。 Calcination temperature is 650 to 800 ° C, preferably 680 to 780 ° C, more preferably 690 to 760 ° C, and further preferably 700 to 750 ° C. By calcining at this temperature, a calcined metal complex as a catalyst component having high ORR catalyst activity and durability can be obtained.
　上記第１実施形態と同様に、還元性ガスには、アンモニアガス、を用いることができる。 As in the first embodiment, ammonia gas can be used as the reducing gas.
　焼成処理は、電極触媒を熱処理するための公知の方法で行い得る。例えば、重合体金属錯体の粉末を還元性ガス雰囲気下において前記焼成温度で、30分間～3時間、好ましくは1時間～2時間焼成すればよい。 The calcination treatment can be performed by a known method for heat-treating the electrode catalyst. For example, the powder of the polymer metal complex may be calcined in the reducing gas atmosphere at the calcining temperature for 30 minutes to 3 hours, preferably 1 hour to 2 hours.
　焼成処理後に、不溶性物質及び非活性触媒を除くため焼成金属錯体を塩酸、硝酸又は硫酸溶液等で酸洗処理（pre-leach）することが好ましい。酸洗処理後は、水（脱イオン水、蒸留水を含む）等で十分に洗浄し、続いて遠心又はろ過によって回収した後、乾燥させることで、目的とする焼成金属錯体を得ることができる。 After the calcination treatment, the calcination metal complex is preferably pre-leached with hydrochloric acid, nitric acid or sulfuric acid solution to remove insoluble substances and inactive catalysts. After the pickling treatment, the target baked metal complex can be obtained by thoroughly washing with water (including deionized water and distilled water), etc., and then recovering by centrifugation or filtration, followed by drying. .
　得られた焼成金属錯体は、比表面積を増大させるために水晶乳鉢等を用いて粉末化し、微小粒子にすることが好ましい。 In order to increase the specific surface area, the obtained fired metal complex is preferably powdered using a crystal mortar or the like into fine particles.
　本工程で得られた焼成金属錯体は、触媒成分であることから、そのまま本発明の電極触媒として用いることもできる。 Since the calcined metal complex obtained in this step is a catalyst component, it can be used as it is as the electrode catalyst of the present invention.
２－３．効果
　本発明によれば、Pt系触媒やCoTMPP触媒のような公知の電極触媒と比較して同等又はより高いORR触媒活性、耐久性及び耐食性を有する電極触媒を、低コストで、かつ比較的簡便な製造方法を提供することができる。 2-3. Effect According to the present invention, an electrode catalyst having the same or higher ORR catalytic activity, durability and corrosion resistance as compared with known electrode catalysts such as Pt-based catalysts and CoTMPP catalysts can be obtained at low cost and relatively easily. A simple manufacturing method can be provided.
３．ガス拡散電極
３－１．概要
　本発明の第３の実施形態は、ガス拡散電極（燃料電池用電極）である。 3. Gas diffusion electrode 3-1. Outline The third embodiment of the present invention is a gas diffusion electrode (electrode for fuel cell).
　本明細書でいう「燃料電池」は、固体高分子型燃料電池（PEFC：Polymer Electrolyte Fuel Cell）及びリン酸型燃料電池（PAFC：Phosphoric Acid Fuel Cell）のような水素燃料電池、並びに微生物燃料電池（MFC：Microbial Fuel Cell）を含む。これらの燃料電池の具体的な説明については、後述の「４．燃料電池」の項で説明する。 As used herein, the term “fuel cell” refers to a solid polymer fuel cell (PEFC) (Polymer Electrolyte Fuel Cell) and a phosphoric acid fuel cell (PAFC) (Phosphoric Fuel Acid Cell), and a microbial fuel cell. (MFC: Microbial Fuel Cell). Specific description of these fuel cells will be described in the section “4. Fuel Cell” described later.
３－２．構成
　本発明のガス拡散電極は、電極触媒及び該電極触媒を担持する導電性担体を含む。また、必要に応じて、さらに支持体を含むこともできる。以下、それぞれの構成要素について具体的に説明をする。 3-2. Configuration The gas diffusion electrode of the present invention includes an electrode catalyst and a conductive carrier that supports the electrode catalyst. Moreover, a support body can also be included as needed. Hereinafter, each component will be specifically described.
（１）電極触媒
　本発明のガス拡散電極は、第１実施形態に記載の電極触媒又は第２実施形態に記載の製造方法で得られる電極触媒を含む。それぞれの電極触媒の構成については、上記実施形態で詳述したことから、ここでの説明は省略する。 (1) Electrode catalyst The gas diffusion electrode of this invention contains the electrode catalyst obtained by the electrode catalyst as described in 1st Embodiment, or the manufacturing method as described in 2nd Embodiment. Since the configuration of each electrode catalyst has been described in detail in the above embodiment, a description thereof is omitted here.
　電極触媒は、本発明のガス拡散電極が反応ガス又は電子供与微生物間でORRを行い得るように、少なくともその一部が当該電極の表面に配置されていればよい。 The electrode catalyst may be at least partially disposed on the surface of the electrode so that the gas diffusion electrode of the present invention can perform ORR between the reaction gas or the electron donating microorganisms.
（２）導電性担体
　「導電性担体」とは、導電性を有し、かつ電極触媒を担持し得る物質をいう。前記特性を有する物質であれば材質は特に限定はしない。例えば、炭素系物質、導電性ポリマー、半導体、金属等が挙げられる。 (2) Conductive carrier "Conductive carrier" refers to a substance having conductivity and capable of supporting an electrode catalyst. The material is not particularly limited as long as it has the above characteristics. For example, a carbonaceous material, a conductive polymer, a semiconductor, a metal, etc. are mentioned.
　本明細書において「炭素系物質」とは、炭素（C）を構成成分とする物質をいう。例えば、グラファイト、活性炭、カーボンパウダ（例えば、カーボンブラック、バルカンXC-72R、アセチレンブラック、ファーネスブラック、デンカブラックを含む）、カーボンファイバ（グラファイトフェルト、カーボンウール、カーボン織布を含む）、カーボンプレート、カーボンペーパー、カーボンディスクや、さらにカーボンナノチューブ、カーボンナノホーン及びカーボンナノクラスターのような微細構造物質が該当する。 In this specification, “carbon-based substance” refers to a substance containing carbon (C) as a constituent component. For example, graphite, activated carbon, carbon powder (including carbon black, Vulcan XC-72R, acetylene black, furnace black, Denka black), carbon fiber (including graphite felt, carbon wool, carbon woven fabric), carbon plate, This includes carbon paper, carbon discs, and also fine structure materials such as carbon nanotubes, carbon nanohorns and carbon nanoclusters.
　本明細書において「導電性ポリマー」とは、導電性を有する高分子化合物の総称をいう。例えば、アニリン、アミノフェノール、ジアミノフェノール、ピロール、チオフェン、パラフェニレン、フルオレン、フラン、アセチレン若しくはそれらの誘導体を構成単位とする単一モノマー又は2種以上のモノマーの重合体が挙げられる。具体的には、例えば、ポリアニリン、ポリアミノフェノール、ポリジアミノフェノール、ポリピロール、ポリチオフェン、ポリパラフェニレン、ポリフルオレン、ポリフラン、ポリアセチレンが該当する。 In this specification, the “conductive polymer” is a generic term for polymer compounds having conductivity. For example, a single monomer or a polymer of two or more monomers having aniline, aminophenol, diaminophenol, pyrrole, thiophene, paraphenylene, fluorene, furan, acetylene, or a derivative thereof as a structural unit can be given. Specifically, for example, polyaniline, polyaminophenol, polydiaminophenol, polypyrrole, polythiophene, polyparaphenylene, polyfluorene, polyfuran, and polyacetylene are applicable.
　入手の容易性、コスト、耐食性、耐久性等を考慮した場合、好適な導電性担体は、炭素系物質であるが、本発明では、これに限定はされない。 In consideration of availability, cost, corrosion resistance, durability, and the like, a suitable conductive support is a carbon-based material, but the present invention is not limited thereto.
　担体は、単一種で構成されていてもよいし、2種以上を組み合わせたものであってもよい。例えば、炭素系物質と導電性ポリマーを組み合わせた担体、又は同じ炭素系物質であるカーボンパウダとカーボンペーパーを組み合わせた担体を使用することができる。 The carrier may be composed of a single species or a combination of two or more species. For example, a carrier combining a carbon-based material and a conductive polymer, or a carrier combining a carbon powder and carbon paper, which are the same carbon-based material, can be used.
　担体の形状は、表面に第１実施形態の電極触媒を担持し得る形状であれば特に限定はしない。ガス拡散電極における単位質量あたりの触媒活性（質量活性）をより高くすることを目的とするのであれば、単位質量当たりの比表面積が大きい粉末形状又は繊維形状が好ましい。担体は、一般に比表面積が大きいほど広い担持面積を確保することができ、触媒成分の担体表面上での分散性を高め、さらにより多くの触媒成分をその表面に担持することが可能となるからである。したがって、カーボンパウダのような微粒子形状やカーボンファイバのような微細繊維形状は、担体形状として好適である。平均粒径が1nm～1μmの微小粉末は特に好ましい。例えば、平均粒径が10nm～300μm程度のカーボンブラックは、本工程の担体として好適である。 The shape of the carrier is not particularly limited as long as the shape can support the electrode catalyst of the first embodiment on the surface. For the purpose of further increasing the catalytic activity (mass activity) per unit mass in the gas diffusion electrode, a powder shape or fiber shape having a large specific surface area per unit mass is preferable. In general, the larger the specific surface area of the support, the larger the support area can be secured, the dispersibility of the catalyst component on the support surface can be improved, and more catalyst components can be supported on the surface. It is. Accordingly, a fine particle shape such as carbon powder and a fine fiber shape such as carbon fiber are suitable as the carrier shape. A fine powder having an average particle diameter of 1 nm to 1 μm is particularly preferable. For example, carbon black having an average particle size of about 10 nm to 300 μm is suitable as a carrier in this step.
　また、担体は、燃料電池電極と外部回路とを連絡する導線との接続端子をその一部に有する。 In addition, the carrier has a connection terminal for a lead wire connecting the fuel cell electrode and an external circuit in a part thereof.
（３）支持体
　「支持体」は、それ自身が剛性を有し、本発明のガス拡散電極に一定の形状を付与することのできる物質をいう。導電性担体が粉末形状等の場合、電極触媒を担持した導電性担体のみではガス拡散電極として一定の形状を保持することができない。また、導電性担体が薄層状態の場合には、担体自体が剛性を有していない。このような場合、電極触媒を担持した導電性担体を支持体表面に配置することで、電極として一定の形状及び剛性が付与される。 (3) Support The “support” refers to a substance that itself has rigidity and can give a certain shape to the gas diffusion electrode of the present invention. When the conductive carrier is in a powder form or the like, it is impossible to maintain a certain shape as a gas diffusion electrode only with the conductive carrier carrying the electrode catalyst. Further, when the conductive carrier is in a thin layer state, the carrier itself does not have rigidity. In such a case, a certain shape and rigidity are imparted as an electrode by disposing a conductive carrier carrying an electrode catalyst on the surface of the support.
　ただし、支持体は、本発明のガス拡散電極の必須の構成要素ではない。例えば、カーボンディスクのように導電性担体自身が一定の形状と剛性を有する場合には、電極触媒を担持した導電性担体のみでガス拡散電極として一定の形状を保持することができる。また、電解質材自体がガス拡散電極に一定の形状と剛性を付与する場合もある。例えば、PEFCでは固体高分子電解質膜の両面に薄層電極が接合されている。このような場合には、必ずしも支持体は必要とされない。したがって、支持体は、必要に応じて、本発明のガス拡散電極に加えればよい。 However, the support is not an essential component of the gas diffusion electrode of the present invention. For example, when the conductive carrier itself has a certain shape and rigidity, such as a carbon disk, it is possible to maintain a certain shape as a gas diffusion electrode only by the conductive carrier carrying the electrode catalyst. Further, the electrolyte material itself may give a certain shape and rigidity to the gas diffusion electrode. For example, in PEFC, thin layer electrodes are bonded to both sides of a solid polymer electrolyte membrane. In such a case, the support is not necessarily required. Therefore, the support may be added to the gas diffusion electrode of the present invention as necessary.
　支持体の材質は、電極が一定の形状を保持できる程度の剛性を有していれば特に限定はしない。また、絶縁体であるか又は導電体であるかは問わない。絶縁体の場合、例えば、ガラス、プラスチック、合成ゴム、セラミックス、又は耐水若しくは撥水処理した紙や植物片（例えば、木片を含む）、動物片（例えば、骨片、貝殻、スポンジを含む）が挙げられる。多孔質構造の支持体は、電極触媒を担持した導電性担体を接合する比表面積が増加し、電極の質量活性を増大できることから、より好ましい。多孔質構造の支持体としては、例えば、多孔質セラミック、多孔質プラスチック、動物片等が挙げられる。導電体の場合、炭素系物質（例えば、カーボンペーパー、カーボンファイバ、炭素棒を含む）、金属、導電性ポリマー等が挙げられる。支持体が導電体の場合には、電極触媒を担持した導電性担体をその表面に配置することで支持体かつ集電体として機能し得る。 The material of the support is not particularly limited as long as the electrode is rigid enough to maintain a certain shape. It does not matter whether it is an insulator or a conductor. In the case of an insulator, for example, glass, plastic, synthetic rubber, ceramics, or water- or water-repellent treated paper or plant pieces (including wood pieces), animal pieces (eg bone pieces, shells, sponges) Can be mentioned. A support having a porous structure is more preferable because the specific surface area for joining the conductive support carrying the electrode catalyst is increased and the mass activity of the electrode can be increased. Examples of the support having a porous structure include porous ceramics, porous plastics, animal pieces, and the like. In the case of a conductor, a carbonaceous material (for example, including carbon paper, carbon fiber, and carbon rod), metal, conductive polymer, and the like can be given. When the support is a conductor, it can function as a support and a current collector by disposing a conductive carrier carrying an electrode catalyst on its surface.
　本発明のガス拡散電極が支持体を含む場合、通常、支持体の形状がガス拡散電極の形状を反映する。支持体の形状は、電極としての機能を果たすことができる形状であれば、特に限定はしない。燃料電池の形状等に応じて適宜定めればよい。例えば、（略）平板状（薄層状を含む）、（略）柱状、（略）球状又はそれらの組み合わせが挙げられる。 When the gas diffusion electrode of the present invention includes a support, the shape of the support usually reflects the shape of the gas diffusion electrode. The shape of the support is not particularly limited as long as it can serve as an electrode. What is necessary is just to determine suitably according to the shape etc. of a fuel cell. For example, (substantially) flat (including thin layer), (substantially) columnar, (substantially) spherical, or a combination thereof may be mentioned.
３－３．方法
（１）電極触媒担持方法
　電極触媒を導電性担体に担持させる方法には、当該分野で公知の方法を用いることができる。例えば、適当な固着剤を用いて導電性担体表面に焼成金属錯体を固定させる方法が挙げられる。固着剤は導電性があれば好ましいが、限定はしない。例えば、前記導電性ポリマーを適当な溶剤に溶解した導電性ポリマー溶液やポリテトラフルオロエチレン（PTFE）の分散液等を固着剤として用いることができる。そのような固着剤を、導電性担体表面及び／又は電極触媒表面に塗布して又は吹き付けて両者を混合するか、又は固着剤の溶液中に含侵した後、乾燥させることで電極触媒の導電性担体への担持を達成し得る。また、導電性担体と焼成金属錯体を水等の溶媒中で混合し、水酸化ナトリウム等の塩基を添加することで、焼成金属錯体を導電性担体表面に析出させて担持させる方法も使用することができる。 3-3. Method (1) Electrocatalyst Support Method As a method for supporting the electrode catalyst on a conductive carrier, a method known in the art can be used. For example, a method of fixing the fired metal complex on the surface of the conductive support using an appropriate fixing agent can be mentioned. The fixing agent is preferably conductive, but is not limited. For example, a conductive polymer solution obtained by dissolving the conductive polymer in a suitable solvent, a polytetrafluoroethylene (PTFE) dispersion, or the like can be used as the fixing agent. Such a sticking agent is applied or sprayed on the surface of the conductive support and / or the surface of the electrode catalyst to mix them together, or impregnated in a solution of the sticking agent and then dried to conduct the electrocatalyst. Loading on a functional carrier can be achieved. Also, use a method in which a conductive carrier and a fired metal complex are mixed in a solvent such as water, and a base such as sodium hydroxide is added to deposit and support the fired metal complex on the surface of the conductive carrier. Can do.
（２）ガス拡散電極形成方法
　ガス拡散電極を形成させる方法は、当該分野で公知の方法を用いることができる。例えば、電極触媒を担持した導電性担体をPTFEの分散液（例えば、Nafion（商標登録；Du Pont社）溶液）等と混合して、適当な形状に成型した後、熱処理を行ってガス拡散電極を形成することができる。PEFCやPAFCのように、固体高分子電解質膜や電解質マトリクス層の表面に電極形成をする場合には、前記混合液をシート状に成型し、形成された電極シートの膜接合面にプロトン伝導性を有するフッ素樹脂系イオン交換膜の溶液等を塗布又は含侵した後、膜両面に重ねてホットプレスして膜に接合すればよい。プロトン伝導性を有するフッ素樹脂系イオン交換膜には、例えば、Nafion、Flemion（登録商標；旭硝子社）等を使用することができる。 (2) Gas diffusion electrode formation method As a method for forming the gas diffusion electrode, a method known in the art can be used. For example, a conductive carrier carrying an electrode catalyst is mixed with a PTFE dispersion (for example, Nafion (registered trademark; DuPont) solution), etc., molded into an appropriate shape, and then subjected to heat treatment to form a gas diffusion electrode. Can be formed. When forming an electrode on the surface of a solid polymer electrolyte membrane or electrolyte matrix layer, such as PEFC or PAFC, the mixed solution is formed into a sheet shape, and proton conductivity is formed on the membrane bonding surface of the formed electrode sheet. After applying or impregnating a fluororesin ion-exchange membrane solution or the like having the above, it may be hot-pressed on both sides of the membrane and bonded to the membrane. For example, Nafion, Flemion (registered trademark; Asahi Glass Co., Ltd.) or the like can be used for the fluorine resin ion exchange membrane having proton conductivity.
　また、前記混合液からなる混合スラリーをカーボンペーパー等の導電性の支持体表面上に塗布した後、熱処理を行い、ガス拡散電極を形成することができる。 Moreover, after applying the mixed slurry made of the mixed solution on the surface of a conductive support such as carbon paper, heat treatment can be performed to form a gas diffusion electrode.
　さらに、プロトン伝導性イオン交換膜の溶液（例えば、Nafion溶液）と電極触媒を担持した導電性担体との混合インク又は混合スラリーを支持体、固体高分子電解質膜又は電解質マトリクス層等の表面に塗布して形成させてもよい。 Furthermore, a mixed ink or mixed slurry of a solution of proton conductive ion exchange membrane (for example, Nafion solution) and a conductive carrier carrying an electrode catalyst is applied to the surface of a support, a solid polymer electrolyte membrane, an electrolyte matrix layer, or the like. May be formed.
３－４．効果
　本発明によれば、Pt系触媒と比較して触媒活性能、耐久性及び耐食性が同等又はより高く、かつ従来のPt系触媒よりも低廉で、安定的に供給が可能なガス拡散電極を提供することができる。 3-4. Advantageous Effects of the Invention According to the present invention, there is provided a gas diffusion electrode that has the same or higher catalytic activity, durability, and corrosion resistance than a Pt-based catalyst, and that can be stably supplied at a lower cost than a conventional Pt-based catalyst. Can be provided.
４．燃料電池
４－１．概要
　本発明の第４の実施形態は、燃料電池である。本発明の燃料電池は、第３実施形態に記載のガス拡散電極を備えることを特徴とする。 4). Fuel cell 4-1. Outline The fourth embodiment of the present invention is a fuel cell. A fuel cell according to the present invention includes the gas diffusion electrode described in the third embodiment.
　本実施形態の燃料電池は、上述のように水素燃料電池又はMFCに好適に用いることができる。 The fuel cell of the present embodiment can be suitably used for a hydrogen fuel cell or MFC as described above.
　水素燃料電池は、水の電気分解の逆動作に基づいて水素と酸素から電気エネルギーを得る燃料電池であり、PEFC、PAFC、アルカリ型燃料電池（AFC; Alcaline Fuell Cell）、溶融炭酸塩型燃料電池（MCFC;Molten Cabonate Fuell Cell）、固体電解質型燃料電池（SOFC; Solid Oxide Fuell Cell）等が知られているが、本発明の燃料電池には、PEFC及びPAFCが好ましい。PEFCはプロトン伝導性イオン交換膜を、またPAFCはマトリクス層に含侵されたリン酸（H3PO4）を、それぞれ電解質材とする燃料電池である。 A hydrogen fuel cell is a fuel cell that obtains electrical energy from hydrogen and oxygen based on the reverse action of water electrolysis. PEFC, PAFC, alkaline fuel cell (AFC), molten carbonate fuel cell (MCFC: Molten Cabonate Fuel Cell), solid oxide fuel cell (SOFC), etc. are known, but PEFC and PAFC are preferred for the fuel cell of the present invention. PEFC is a proton conductive ion exchange membrane, and PAFC is a fuel cell using phosphoric acid (H 3 PO 4 ) impregnated in a matrix layer as an electrolyte material.
　MFCは、アノードにおいて電子供与微生物が水素に代わる電子供与体として機能する事を特徴とする。電子供与微生物には、シェワネラ（Shewanella）属（例えば、シェワネラ・ロイヒカ；S. loihica、シェワネラ・オネイデンシス；S. oneidensis、シェワネラ・プトレファシエンス；S. putrefaciens、及びシェワネラ・アルガ；S. algae）、シュードモナス（Pseudomonas）属（例えば、シュードモナス・エアルギノーザ；P. aeruginosa）、ロドフェラックス（Rhodoferax）属（例えば、ロドフェラックス・フェリレドゥセンス；R. ferrireducens）、及びジオバクター（Geobacter）属（例えば、ジオバクター・サルフレドゥセンス；G. sulfurreducens、ジオバクター・メタリレドゥセンス；G.metallireducens）等を用いることができる。 MFC is characterized in that the electron donating microorganism functions as an electron donor replacing hydrogen in the anode. Electron-donating microorganisms include the genus Shewanella (eg, Shewanella leuhica; S. loihica, Shewanella oneidensis; S. oneidensis, Shewanella putrefaciens; S. putrefaciens, and S. algae). Pseudomonas genus (eg P. aeruginosa), Rhodoferax genus (eg Rhoferferax ferrireducens), and Geobacter genus (eg G. sulfurreducens, G. metallireducens; G. metallireducens) and the like can be used.
４－２．構成
　本発明の燃料電池は、電極に第３実施形態のガス拡散電極を用いること除いて、各燃料電池で公知の構成を有していればよい。例えば、「燃料電池の技術」，電気学会燃料電池発電次世代システム技術調査専門委員会編，オーム社，H17や、Watanabe, K., J. Biosci. Bioeng., 2008,.106:528-536に記載の構成を有することができる。 4-2. Configuration The fuel cell of the present invention may have a known configuration in each fuel cell except that the gas diffusion electrode of the third embodiment is used as an electrode. For example, “Technology for Fuel Cell”, edited by the IEEJ Fuel Cell Power Generation Next Generation System Technology Research Special Committee, Ohm, H17, Watanabe, K., J. Biosci. Bioeng., 2008, .106: 528-536 It can have the structure described in the above.
　本発明の燃料電池において、第３実施形態のガス拡散電極は、アノード（燃料極）又はカソード（空気極）のいずれにも用いることができる。水素燃料電池で、第３実施形態のガス拡散電極をアノードに用いた場合、電極に包含される本発明の電極触媒が燃料である水素ガスのH2→H+＋2e-の反応を触媒して、アノードに電子を供与する。カソードに用いた場合、酸化剤である酸素ガスの1/2O2＋2H++2e-→H2Oの反応を触媒する。一方、MFCでは、アノードが電子供与微生物から直接電子を受容するため、本発明のガス拡散電極は、主として水素燃料電池と同じ電極反応を起こすカソードに用いられる。 In the fuel cell of the present invention, the gas diffusion electrode of the third embodiment can be used for either the anode (fuel electrode) or the cathode (air electrode). In the hydrogen fuel cell, when the gas diffusion electrode of the third embodiment is used as an anode, the electrode catalyst of the present invention included in the electrode catalyzes the reaction of H 2 → H + + 2e − of hydrogen gas as a fuel. , Donate electrons to the anode. When used in the cathode, 1 / 2O 2 + 2H + + 2e of the oxygen gas as an oxidizing agent - → H 2 O to catalyze the reaction of. On the other hand, in MFC, since the anode accepts electrons directly from electron donating microorganisms, the gas diffusion electrode of the present invention is mainly used as a cathode that causes the same electrode reaction as that of a hydrogen fuel cell.
４－３．効果
　本発明によれば、Pt系触媒を含むガス拡散電極を用いた従来の燃料電池よりもエネルギー変換効率能が高く、かつ長寿命で低廉な燃料電池を提供することができる。また、使用する電極触媒の触媒金属に、安価で可採埋蔵量の多い金属を使用できることから、燃料電池の将来の量産化に対応でき、また燃料電池分野において燃料電池の民生用用途への普及にも貢献し得る。 4-3. Advantageous Effects of the Invention According to the present invention, it is possible to provide a fuel cell that has a higher energy conversion efficiency than a conventional fuel cell that uses a gas diffusion electrode containing a Pt-based catalyst, has a long life, and is inexpensive. In addition, it is possible to use low-priced, highly recoverable metals for the catalyst metal of the electrode catalyst to be used, so that it can be used for future mass production of fuel cells, and the diffusion of fuel cells to consumer applications in the fuel cell field Can also contribute.
＜実施例１：電極触媒の調製＞
（実験例１）Co-2,6-ジアミノピリジンポリマー（CoDAPP）触媒の調製
　CoDAPP触媒は、本発明の第２実施形態の方法に従った。2,6-ジアミノピリジンモノマー（Aldrich社）と酸化剤ペルオキシ二硫酸アンモニウム（APS）（Wako社）を1：1.5のモル比で混合し、撹拌した。具体的には、5.45gの2,6-ジアミノピリジンと1gの水酸化ナトリウムを400mLの蒸留水に溶かし、その後27.6gのAPSと100mLの水を加えた。得られた混合物を5分間撹拌し、室温で12時間、2,6-ジアミノピリジンを重合させた。重合反応後、得られた黒色の沈殿物を3000rpmで遠心して回収し、蒸留水で3回洗浄した。真空下で60℃にて数時間乾燥させて2,6-ジアミノピリジンポリマーを得た。 <Example 1: Preparation of electrode catalyst>
Experimental Example 1 Preparation of Co-2,6-diaminopyridine polymer (CoDAPP) catalyst The CoDAPP catalyst followed the method of the second embodiment of the present invention. 2,6-diaminopyridine monomer (Aldrich) and oxidizing agent ammonium peroxydisulfate (APS) (Wako) were mixed at a molar ratio of 1: 1.5 and stirred. Specifically, 5.45 g of 2,6-diaminopyridine and 1 g of sodium hydroxide were dissolved in 400 mL of distilled water, and then 27.6 g of APS and 100 mL of water were added. The resulting mixture was stirred for 5 minutes, and 2,6-diaminopyridine was polymerized at room temperature for 12 hours. After the polymerization reaction, the resulting black precipitate was collected by centrifugation at 3000 rpm and washed three times with distilled water. It was dried at 60 ° C. for several hours under vacuum to obtain 2,6-diaminopyridine polymer.
　2,6-ジアミノピリジン（原料モノマー）とコバルト（触媒金属原子）のモル比が4:１となるように、5.45gの2,6-ジアミノピリジンポリマーと3.62ｇの硝酸コバルトCo(NO3)2（和光純薬）と150mLの水：エタノール（1：1）溶液に懸濁した。同様に、2,6-ジアミノピリジンとコバルトのモル比が6:1、8：1、10：1となるように、モル比から、2,6-ジアミノピリジンポリマー及び硝酸コバルトそれぞれの量を算出し、配合した。懸濁液をsonicator ultrasonic probe systems（アズワン(株)）で1時間超音波混合して、さらに60℃で2時間撹拌した後、溶液を蒸発させた。残った2,6-ジアミノピリジンポリマーとコバルトからなる重合体金属錯体の粉末を水晶乳鉢ですりつぶした。 5.45 g of 2,6-diaminopyridine polymer and 3.62 g of cobalt nitrate Co (NO 3 ) so that the molar ratio of 2,6-diaminopyridine (raw monomer) to cobalt (catalytic metal atom) is 4: 1. 2 (Wako Pure Chemical Industries) and 150 mL of water: ethanol (1: 1) suspension. Similarly, the amounts of 2,6-diaminopyridine polymer and cobalt nitrate are calculated from the molar ratio so that the molar ratio of 2,6-diaminopyridine to cobalt is 6: 1, 8: 1, 10: 1. And blended. The suspension was subjected to ultrasonic mixing with sonicator ultrasonic probe systems (As One Co., Ltd.) for 1 hour and further stirred at 60 ° C. for 2 hours, and then the solution was evaporated. The remaining powder of the polymer metal complex consisting of 2,6-diaminopyridine polymer and cobalt was ground in a crystal mortar.
　前記重合体金属錯体をアンモニアガス雰囲気下で700℃にて1.5時間焼成した。得られた焼成金属錯体を12規定の塩酸溶液で8時間超音波酸洗処理（pre-leach）し、不溶性物質及び非活性物質を除き、続いて脱イオン水で十分に洗浄した。最後に、本発明の電極触媒である焼成金属錯体をろ過により回収し、60℃で乾燥させた。 The polymer metal complex was baked at 700 ° C. for 1.5 hours in an ammonia gas atmosphere. The obtained calcined metal complex was subjected to ultrasonic pre-leach with a 12 N hydrochloric acid solution for 8 hours to remove insoluble substances and inactive substances, and then thoroughly washed with deionized water. Finally, the calcined metal complex which is the electrode catalyst of the present invention was recovered by filtration and dried at 60 ° C.
（実験例２）Fe-2,6-ジアミノピリジンポリマー（FeDAPP）触媒の調製
　触媒金属原子として、硝酸コバルトに代えて鉄（硝酸鉄(II)；和光純薬）を使用したことを除いて、実施例１（実験例１）と同様の操作を行った。 (Experimental example 2) Preparation of Fe-2,6-diaminopyridine polymer (FeDAPP) catalyst Except for using iron (iron nitrate (II); Wako Pure Chemical Industries) instead of cobalt nitrate as the catalyst metal atom, The same operation as in Example 1 (Experimental Example 1) was performed.
（実験例３）Fe/Co-2,6-ジアミノピリジンポリマー（Fe/CoDAPP）触媒の調製
　触媒金属原子として、硝酸コバルトに加えて硝酸鉄(III)（和光純薬）を使用したことを除いて、実施例１（実験例１）と同様の操作を行った。なお、硝酸コバルトと硝酸鉄(III)のモル混合比は、1:1、PAPA/Co(NO3)2/Fe(NO3)3 のモル混合比は 8:1:1とした。 (Experimental example 3) Preparation of Fe / Co-2,6-diaminopyridine polymer (Fe / CoDAPP) catalyst Except that iron nitrate (III) (Wako Pure Chemical Industries) was used in addition to cobalt nitrate as the catalyst metal atom. Then, the same operation as in Example 1 (Experimental Example 1) was performed. The molar mixing ratio of cobalt nitrate and iron (III) nitrate was 1: 1, and the molar mixing ratio of PAPA / Co (NO3) 2 / Fe (NO3) 3 was 8: 1: 1.
（比較例１）CoTMPP触媒（CoTMPP電極）の調製
　CoTMPP触媒の調製は、Dengらの方法（Liu Deng, Ming Zhou, Chang Liu, Ling Liu, Changyun Liu, Shaojun Dong, 2010, Talanta 81: 444-448）に準じた。なお、CoTMPP触媒の調製では、焼成時に導電性担体となるカーボンと混合状態であることから、結果的に触媒調製と同時に電極調製が行われることになる。このようなCoTMPP触媒を含む電極を本明細書では、「CoTMPP電極」と呼ぶ。 Comparative Example 1 Preparation of CoTMPP Catalyst (CoTMPP Electrode) CoTMPP catalyst was prepared by the method of Deng et al. (Liu Deng, Ming Zhou, Chang Liu, Ling Liu, Changyun Liu, Shaojun Dong, 2010, Talanta 81: 444-448 ). In the preparation of the CoTMPP catalyst, since it is in a mixed state with carbon that becomes a conductive carrier at the time of firing, as a result, the electrode is prepared simultaneously with the catalyst preparation. In the present specification, an electrode including such a CoTMPP catalyst is referred to as a “CoTMPP electrode”.
　まず、炭素微粒子バルカンXC-72Rを6M硝酸溶液中で1時間超音波処理した後、100℃にて6時間で処理し、続いて、脱イオン水で3回洗浄した。最後に、3000rpmで遠心して回収し、真空下で乾燥させた。 First, the carbon fine particle Vulcan XC-72R was sonicated in a 6M nitric acid solution for 1 hour, then treated at 100 ° C. for 6 hours, and then washed with deionized water three times. Finally, it was collected by centrifugation at 3000 rpm and dried under vacuum.
　0.9gの荷電したバルカンXC-72Rと0.1gのCoTMPP（コバルト－テトラメトキシフェニルポルフィリン；Cobalt TetraMethoxyPhenylPorphyrin）をアセトン中に分散させ、60℃にて12時間で還流した。続いて、真空下で乾燥させた。得られたCoTMPPとバルカンXC-72Rからなるハイブリッド粉末を750℃で2時間熱処理した。熱処理した試料を、その後、塩酸溶液で8時間超音波酸洗処理（pre-leach）を行い、不溶性物質及び非活性物質を触媒から除去し、脱イオン水で十分に洗浄した。最後に、サンプルをろ過して60℃で乾燥させた。 0.9 g of charged Vulcan XC-72R and 0.1 g of CoTMPP (cobalt-tetramethoxyphenylporphyrin) were dispersed in acetone and refluxed at 60 ° C. for 12 hours. Subsequently, it was dried under vacuum. The obtained hybrid powder composed of CoTMPP and Vulcan XC-72R was heat-treated at 750 ° C. for 2 hours. The heat treated sample was then ultrasonically pickled with hydrochloric acid solution for 8 hours to remove insoluble and inactive materials from the catalyst and washed thoroughly with deionized water. Finally, the sample was filtered and dried at 60 ° C.
（比較例２）CoPPy触媒（CoPPy電極）の調製
　4-トルエンスルホン酸（TsOH）をドープしたポリピロールの合成は、非特許文献２に開示の方法に準じた。なお、本CoPPy触媒もCoTMPP触媒と同様に、焼成時に導電性担体となるカーボンと混合していることから、CoPPy触媒を含む電極を本明細書では、「CoPPy電極」と呼ぶ。 Comparative Example 2 Preparation of CoPPy Catalyst (CoPPy Electrode) Synthesis of polypyrrole doped with 4-toluenesulfonic acid (TsOH) was performed in accordance with the method disclosed in Non-Patent Document 2. The CoPPy catalyst is also mixed with carbon that becomes a conductive carrier at the time of calcination, like the CoTMPP catalyst. Therefore, an electrode including the CoPPy catalyst is referred to as a “CoPPy electrode” in this specification.
　まず、0.6gのバルカンXC-72Rを比較例１と同様の方法で処理した。その後、3mmolのピロールと100mLの再蒸留水を添加し、混合物をさらに30分間撹拌した。続いて、100mLの0.06mol/L APS溶液と0.1902gの4-トルエンスルホン酸（TsOH）を加えた。その後、室温で4時間撹拌し、その後、混合物をろ過して、少なくとも3回再蒸留水とアルコールで交互に洗浄した。最後に真空下で12時間乾燥させて、残った粉末を水晶乳鉢ですりつぶした。 First, 0.6 g of Vulcan XC-72R was treated in the same manner as in Comparative Example 1. Then 3 mmol of pyrrole and 100 mL of double distilled water were added and the mixture was stirred for another 30 minutes. Subsequently, 100 mL of 0.06 mol / L APS solution and 0.1902 g of 4-toluenesulfonic acid (TsOH) were added. The mixture was then stirred at room temperature for 4 hours, after which the mixture was filtered and washed alternately with double distilled water and alcohol at least three times. Finally, it was dried for 12 hours under vacuum, and the remaining powder was ground in a crystal mortar.
　0.5ｇのポリピロール(PPy)-TsOH/Cと0.25gのCo(CH3Coo)2・4H2Oを200mLの再蒸留水に加え、1時間超音波混合して80℃で2時間強く撹拌した後、溶媒を減圧下で蒸発させた。その後、残った粉末を、アルゴンガス雰囲気下800℃で1時間熱処理を行った。熱処理したサンプルをその後塩酸溶液で8時間超音波酸洗処理（pre-leach）し、不溶性物質及び非活性物質を除き、続いて脱イオン水で十分に洗浄した。最後に、サンプルをろ過して60℃で乾燥させた。 0.5 g polypyrrole (PPy) -TsOH / C and 0.25 g Co (CH 3 Coo) 2 · 4H 2 O were added to 200 mL double-distilled water, ultrasonically mixed for 1 hour and stirred vigorously at 80 ° C. for 2 hours. After that the solvent was evaporated under reduced pressure. Thereafter, the remaining powder was heat-treated at 800 ° C. for 1 hour in an argon gas atmosphere. The heat treated sample was then pre-leached with hydrochloric acid solution for 8 hours to remove insoluble and inactive materials, followed by thorough washing with deionized water. Finally, the sample was filtered and dried at 60 ° C.
（比較例３）Pt触媒
　Pt触媒は、市販のPtが導電性担体であるカーボン粒子に担持された電極としての20％Pt/Cナノ粒子を田中貴金属工業から購入し、使用した。Pt担持カーボン電極のようなPt触媒を含む電極を本明細書では、「Pt電極」と呼ぶ。 (Comparative example 3) Pt catalyst The Pt catalyst purchased from Tanaka Kikinzoku Kogyo Co., Ltd. 20% Pt / C nanoparticle as an electrode by which the commercially available Pt was carry | supported by the carbon particle which is an electroconductive support | carrier. In the present specification, an electrode including a Pt catalyst such as a Pt-supported carbon electrode is referred to as a “Pt electrode”.
＜実施例２：触媒活性（１）＞
　実施例１で調製した各電極（実験例２を除く）が包含する触媒の酸素還元反応（ORR）の触媒活性を回転リングディスク電極（RRDE；Rotating Ring-Disk Electrode）を用いたバイポテンショスタット（Pine Instrument社）によって検証した。 <Example 2: Catalytic activity (1)>
Bipotentiostat using a rotating ring-disk electrode (RRDE) for the catalytic activity of the oxygen reduction reaction (ORR) of the catalyst included in each electrode prepared in Example 1 (excluding Experimental Example 2) Verified by Pine Instrument).
[方法]
（１）RRDE電極の調製
　カーボンディスクからなるRRDEを作用電極として用いた。また、白金線及び飽和カロメル電極（SCE；Saturated Calomel Electrode）をそれぞれ対極及び参照電極として用いた。 [Method]
(1) Preparation of RRDE electrode RRDE made of a carbon disk was used as a working electrode. A platinum wire and a saturated calomel electrode (SCE) were used as a counter electrode and a reference electrode, respectively.
　実施例１で調製した電極触媒（CoDAPP触媒及びFeDAPP触媒）、電極（CoTMPP電極、CoPPy電極及びPt電極）各2mgをそれぞれ20μLのNafion（登録商標）溶液（5重量％；Du Pont社）及び1mLのエタノールと混合し、30分間超音波槽内でブレンドして、均一に分散させ、触媒インク又は電極インクを調製した。 2 mg each of the electrode catalyst (CoDAPP catalyst and FeDAPP catalyst) and the electrode (CoTMPP electrode, CoPPy electrode and Pt electrode) prepared in Example 1 were each 20 μL of Nafion (registered trademark) solution (5% by weight; DuDPont) and 1 mL. The catalyst ink or electrode ink was prepared by mixing with ethanol and blending in an ultrasonic bath for 30 minutes and dispersing uniformly.
　0.1mLの触媒インク又は電極インクを上記ディスク電極の表面上に塗布して乾燥させた。その結果、各触媒又は電極を1mg/cm2で担持したRRDE電極が得られた。具体的には、RRDEを導電性担体とし、CoDAPP又はFeDAPPを電極触媒とする電極（このようなCoDAPP触媒又はFeDAPP触媒を含む電極を本明細書ではそれぞれ「CoDAPP電極」又は「FeDAPP電極」と呼ぶ）、または、RRDEをさらなる導電性担体とするCoTMPP電極、CoPPy電極、及びPt電極である。 0.1 mL of catalyst ink or electrode ink was applied onto the surface of the disk electrode and dried. As a result, an RRDE electrode carrying each catalyst or electrode at 1 mg / cm 2 was obtained. Specifically, an electrode using RRDE as a conductive carrier and CoDAPP or FeDAPP as an electrode catalyst (an electrode including such a CoDAPP catalyst or FeDAPP catalyst is referred to as a “CoDAPP electrode” or an “FeDAPP electrode”, respectively in this specification). Or a CoTMPP electrode, a CoPPy electrode, and a Pt electrode using RRDE as a further conductive carrier.
（２）電極の電気化学的測定
　触媒電流の評価は、酸素飽和した0.05MのH2SO4、0.2MのK2H2PO4/KH2PO4及び0.1MのKOH溶液（pH1）中で、室温下5mV/sの電位走査速度と室温下1500rpmの回転速度で測定した。 (2) Electrochemical measurement of electrode The catalyst current was evaluated in oxygen-saturated 0.05M H 2 SO 4 , 0.2M K 2 H 2 PO 4 / KH 2 PO 4 and 0.1M KOH solution (pH 1). Then, measurement was performed at a potential scanning speed of 5 mV / s at room temperature and a rotation speed of 1500 rpm at room temperature.
　ORR間の電子移動の数（n）は、以下の方程式（１）で算出した。 The number (n) of electron transfer between ORRs was calculated by the following equation (1).
　　　n=4iD/(iD+iR/N)　　　　　　　　（１）
　ここで、iDはディスク上の感応電流であり、iRはリング上の感応電流であり、Nは電極の寸法（ディスク外径、リングの外径及び内径）によって決定される収集効率であり、本実施例では、0.19である。走査電位範囲は、RRDE電極のpH値が１に等しいときにSCEに対して0.8～-0.3Vを選択した。 n = 4i D / (i D + i R / N) (1)
Where i D is the sensitive current on the disk, i R is the sensitive current on the ring, and N is the collection efficiency determined by the electrode dimensions (disk outer diameter, ring outer diameter and inner diameter). In this embodiment, it is 0.19. A scanning potential range of 0.8 to −0.3 V was selected for SCE when the pH value of the RRDE electrode was equal to 1.
[結果]
１．CoDAPP電極における2,6-ジアミノピリジンポリマー及び硝酸コバルトの混合比（原料モノマーと触媒金属原子のモル比）とORR触媒活性
　2,6-ジアミノピリジンポリマーと硝酸コバルトを、原料モノマーとコバルトのモル比が4:１、6:1、8：1、10：1となるようにそれぞれ混合し、焼成した焼成金属錯体由来の電極触媒（CoDAPP）において、当該モル比とORR触媒活性の関係を検証した。 [result]
1. Mixing ratio of 2,6-diaminopyridine polymer and cobalt nitrate (molar ratio of raw material monomer and catalytic metal atom) and ORR catalytic activity at CoDAPP electrode and molar ratio of raw material monomer and cobalt with 2,6-diaminopyridine polymer and cobalt nitrate In the electrode catalyst (CoDAPP) derived from the calcined metal complex, the relationship between the molar ratio and the ORR catalyst activity was verified by mixing and calcining to be 4: 1, 6: 1, 8: 1, and 10: 1. .
　図１に結果を示す。図１において、a、b、c、dはそれぞれ、原料モノマー：コバルトのモル比が4:1、6:1、8:1、10:1となるように、2,6-ジアミノピリジンポリマー及び硝酸コバルトを混合して調製した焼成金属錯体CoDAPPを電極触媒として包含するCoDAPP電極のORR触媒活性を示し、ｅはPt電極のORR触媒活性を示す。この図で示すように、CoDAPP電極は、2,6-ジアミノピリジンポリマーと硝酸コバルトがいずれの混合比で混合されてもPt電極と比較して、触媒電流が大きいことが示された。また、モル比が4：1となるように混合したときに、高い活性が得られることが示された。そこで、以降の実験では、2,6-ジアミノピリジンポリマーと硝酸コバルトの混合比が、モノマーと金属の比で4：1となるように選択して調製されたCoDAPP電極を用いて検証を行った。 Figure 1 shows the results. In FIG. 1, a, b, c, and d are 2,6-diaminopyridine polymer and a raw material monomer: cobalt molar ratio of 4: 1, 6: 1, 8: 1, and 10: 1, respectively. The ORR catalytic activity of a CoDAPP electrode including a calcined metal complex CoDAPP prepared by mixing cobalt nitrate as an electrode catalyst is shown, and e shows the ORR catalytic activity of a Pt electrode. As shown in this figure, it was shown that the CoDAPP electrode had a larger catalyst current than the Pt electrode even when 2,6-diaminopyridine polymer and cobalt nitrate were mixed at any mixing ratio. Further, it was shown that high activity can be obtained when mixing is performed so that the molar ratio is 4: 1. Therefore, in the subsequent experiments, verification was performed using a CoDAPP electrode prepared by selecting a mixing ratio of 2,6-diaminopyridine polymer and cobalt nitrate so that the ratio of monomer to metal was 4: 1. .
２．各電極における電極触媒とORR触媒活性の比較
　CoDAPP電極、CoTMPP電極、CoPPy電極及びPt電極に含まれる各電極触媒のORR触媒活性を比較検証した。 2. Comparison of the electrocatalyst and ORR catalytic activity at each electrode The ORR catalytic activity of each electrocatalyst contained in the CoDAPP electrode, CoTMPP electrode, CoPPy electrode and Pt electrode was compared and verified.
　図２に結果を示す。図２において、ａ、ｂ、ｃ、ｄはそれぞれ、CoDAPP電極、CoTMPP電極、CoPPy電極、Pt電極を示す。以下の図３～５においても同様である。まず、上記方程式（１）で算出したORR間の電子移動の数（n）は、CoDAPP電極が3.98、CoTMPP電極が3.91、CoPPy電極が3.68、そしてPt電極が3.99であった。この結果から、酸素還元反応の生成物のほとんどがH2O(4電子還元)であることが判る。 The results are shown in FIG. In FIG. 2, a, b, c, and d indicate a CoDAPP electrode, a CoTMPP electrode, a CoPPy electrode, and a Pt electrode, respectively. The same applies to FIGS. 3 to 5 below. First, the number (n) of electron transfer between ORRs calculated by the above equation (1) was 3.98 for the CoDAPP electrode, 3.91 for the CoTMPP electrode, 3.68 for the CoPPy electrode, and 3.99 for the Pt electrode. From this result, it can be seen that most of the products of the oxygen reduction reaction are H 2 O (4-electron reduction).
　また、一般に、電位を徐々に下げて電流密度を測定した際、初期のスロープに対する立ち下がり電位が高い方が燃料電池として用いた場合に、より高い電圧を得ることができ、また立ち下がりの大きさが大きいほど、より大きな電流を得ることができることが知られている。図２より、CoDAPP電極は、Pt電極と比較して、立ち下がり電位は劣るが、立ち下がり量は優ることから酸素還元触媒として、より大きな電流を得ることが可能なことが立証された。 In general, when the current density is measured by gradually lowering the potential, a higher voltage can be obtained when the higher falling potential with respect to the initial slope is used as a fuel cell. It is known that a larger current can obtain a larger current. FIG. 2 demonstrates that the CoDAPP electrode is inferior to the Pt electrode in falling potential, but the falling amount is superior, so that a larger current can be obtained as an oxygen reduction catalyst.
＜実施例３：触媒活性（２）＞
　実施例１の実験例２で調製したFeDAPP触媒を実施例２と同様の方法を用いてRRDEの表面上に塗布し、そのRRDEを導電性担体として、FeDAPPを電極触媒とする電極（このようなFeDAPP触媒を含む電極を本明細書では「FeDAPP電極」と呼ぶ）を用いて、FeDAPP触媒のORR触媒活性を検証した。 <Example 3: Catalytic activity (2)>
The FeDAPP catalyst prepared in Experimental Example 2 of Example 1 was applied on the surface of RRDE using the same method as in Example 2, and the electrode using such RRDE as a conductive support and FeDAPP as an electrode catalyst (such as The electrode containing the FeDAPP catalyst is referred to as “FeDAPP electrode” in this specification), and the ORR catalytic activity of the FeDAPP catalyst was verified.
[方法]
（１）FeDAPP電極の調製
　実施例２と同様の方法で行った。触媒活性の比較用として実験例１のCoDAPP電極を、同一条件で調製した。 [Method]
(1) Preparation of FeDAPP electrode The same method as in Example 2 was used. For comparison of catalyst activity, the CoDAPP electrode of Experimental Example 1 was prepared under the same conditions.
（２）電極の電気化学的測定
　触媒電流の評価についても、実施例２と同様の方法で行った
[結果]
　図３に結果を示す。この図は、FeDAPP触媒（ａ）又はCoDAPP触媒（ｂ）によるORR触媒活性の比較を示す図である。図３からFeDAPP触媒は、CoDAPP触媒と比較して、立ち下がりのpotentialが高く、立ち下がり量も大きいので、FeDAPPがCoDAPPよりも触媒としての能力が高いことが判る。 (2) Electrochemical measurement of electrode The catalyst current was evaluated in the same manner as in Example 2.
[result]
The results are shown in FIG. This figure is a figure which shows the comparison of the ORR catalyst activity by a FeDAPP catalyst (a) or a CoDAPP catalyst (b). FIG. 3 shows that FeDAPP catalyst has higher falling potential and higher falling amount than CoDAPP catalyst, and therefore FeDAPP has a higher ability as a catalyst than CoDAPP.
＜実施例４：触媒活性（３）＞
　電極触媒が二以上の異なる触媒金属を配位する場合にも、単一の触媒金属を配位する場合と比べて同等又はそれ以上の酸素還元触媒能を有するか否かを調べた。 <Example 4: Catalytic activity (3)>
Whether or not the electrode catalyst has two or more different catalytic metals coordinated with each other compared with a single catalytic metal coordinated was examined.
[方法]
（１）電極の調製
　二以上の異なる触媒金属を配位する電極触媒には、実施例１の実験例３で調製したFe/CoDAPP触媒を実施例２と同様の方法を用いてRRDEの表面上に塗布し、そのRRDEを導電性担体として、Fe/CoDAPPを電極触媒とする電極（このようなFe/CoDAPP触媒を含む電極を本明細書では「Fe/CoDAPP電極」と呼ぶ）を用いた。また、比較用の単一の触媒金属を配位する電極触媒には、実施例２で調製したCoDAPP電極、及び実施例３で調製したFeDAPP電極を用いた。 [Method]
(1) Preparation of electrode For the electrode catalyst coordinating two or more different catalytic metals, the Fe / CoDAPP catalyst prepared in Experimental Example 3 of Example 1 was used on the surface of RRDE using the same method as in Example 2. And an electrode using Fe / CoDAPP as an electrode catalyst (an electrode including such an Fe / CoDAPP catalyst is referred to as an “Fe / CoDAPP electrode” in this specification). Further, the CoDAPP electrode prepared in Example 2 and the FeDAPP electrode prepared in Example 3 were used as the electrode catalyst for coordinating a single catalytic metal for comparison.
（２）電極の電気化学的測定
　調製した各電極触媒を酸素飽和した0.05MのH2SO4、0.2MのK2H2PO4/KH2PO4及び0.1MのKOH溶液（pH1）中で、溶液の水素イオン指数をpH1、pH7及びpH13と変化させたときのORR触媒活性を検証した。触媒電流の評価についても、実施例２と同様の方法で行った
[結果]
　図８～１０に結果を示す。図８、９及び１０は、溶液がそれぞれpH1、pH7及びpH13のときの結果である。各図とも、図中、（ａ）はCoDAPP触媒、（ｂ）はFeDAPP触媒、そして（ｃ）はFe/CoDAPP触媒によるORR触媒活性を示す。 (2) Electrochemical measurement of electrode Each prepared electrocatalyst in oxygen-saturated 0.05M H 2 SO 4 , 0.2M K 2 H 2 PO 4 / KH 2 PO 4 and 0.1M KOH solution (pH 1) The ORR catalytic activity when the hydrogen ion index of the solution was changed to pH 1, pH 7 and pH 13 was verified. The catalyst current was evaluated in the same manner as in Example 2.
[result]
The results are shown in FIGS. 8, 9 and 10 show the results when the solutions are at pH 1, pH 7 and pH 13, respectively. In each figure, (a) shows the CoRAPP catalyst, (b) shows the FeDAPP catalyst, and (c) shows the ORR catalytic activity by the Fe / CoDAPP catalyst.
　まず、上記実施例２に記載の方程式（１）で算出したORR間の電子移動の数（n）は、溶液がpH１のときに、CoDAPP電極が3.98であったのに対して、FeDAPP電極とFe/CoDAPP電極は3.99であった。この結果から、Fe/CoDAPP電極も、酸素還元反応の生成物のほとんどがH2O(4電子還元)であることが判った。 First, the number (n) of electron transfer between ORRs calculated by equation (1) described in Example 2 above was 3.98 for the CoDAPP electrode when the solution was at pH 1, whereas the number of the electron transfer between the FeDAPP electrode and the CoDAPP electrode was 3.98. The Fe / CoDAPP electrode was 3.99. From this result, it was found that most of the products of the oxygen reduction reaction of the Fe / CoDAPP electrode were H 2 O (4-electron reduction).
　また、いずれのpHの場合にも、Fe/CoDAPP電極は、FeDAPP電極及びCoDAPP電極と比較して、立ち下がり電位は同等以上であり、また立ち下がり量は優れていた。したがって、二以上の異なる触媒金属を配位する電極触媒であっても、酸素還元触媒能を有し、特に、FeとCoを配位する電極触媒の場合には、それぞれを単独で配位する電極触媒よりも、酸素還元触媒能がより高いことが明らかとなった。 Also, at any pH, the Fe / CoDAPP electrode had a falling potential equal to or higher than the FeDAPP electrode and CoDAPP electrode, and the amount of falling was excellent. Therefore, even an electrode catalyst that coordinates two or more different catalytic metals has oxygen reduction catalytic ability, and in particular, in the case of an electrode catalyst that coordinates Fe and Co, each coordinates independently. It was revealed that the oxygen reduction catalytic ability was higher than that of the electrode catalyst.
＜実施例５：各電極触媒中の炭素、窒素及び触媒金属の含有比率＞
　実施例１で調製した電極触媒又はそれを含むガス拡散電極における元素組成を、XPS分析法を用いて解析し、各電極触媒における炭素（C）、窒素（N）及び触媒金属であるコバルト（Co）の含有比率を調べた。 <Example 5: Content ratio of carbon, nitrogen and catalyst metal in each electrode catalyst>
The elemental composition of the electrode catalyst prepared in Example 1 or the gas diffusion electrode containing the same was analyzed using XPS analysis, and carbon (C), nitrogen (N) and cobalt (Co ) Content ratio was examined.
[方法]
　CoDAPP触媒、CoTMPP電極及びCoPPy電極の表面化学をX線光電子分光（XPS：X-ray photoelectron spectroscopy）分析法を用いて解析した。 [Method]
The surface chemistry of the CoDAPP catalyst, CoTMPP electrode, and CoPPy electrode was analyzed using X-ray photoelectron spectroscopy (XPS) analysis.
　XPS測定は、XPS装置(Axis Ultra HAS； Kratos Analytical社)を用いて、励起X線としてmonochromatic Al X線(10 kV)を用いた。C、N、O及びCoに関する測定及びナロースキャンスペクトルをCoDAPP触媒、CoTMPP電極及びCoPPy電極について行った。 The XPS measurement was performed using an XPS apparatus (Axis Ultra HAS; Kratos Analytical) and monochromatic Al X-rays (10 KV) as excitation X-rays. Measurements and narrow scan spectra for C, N, O and Co were performed on the CoDAPP catalyst, CoTMPP electrode and CoPPy electrode.
[結果] 
　それぞれのXPS分析の結果を表１に示す。ここで、CoTMPP/C及びCoPPy/Cは、それぞれ炭素微粒子を導電性担体とするCoTMPP電極及びCoPPy電極であることを示す。
Figure JPOXMLDOC01-appb-T000004
 [result]
The results of each XPS analysis are shown in Table 1. Here, CoTMPP / C and CoPPy / C indicate a CoTMPP electrode and a CoPPy electrode using carbon fine particles as a conductive carrier, respectively.
Figure JPOXMLDOC01-appb-T000004
　この表で示すように、塩酸による酸洗処理（酸洗浄）後の本発明のCoDAPP触媒は、炭素に対する窒素の元素比がモル比（N/C）で0.12であった。また、窒素に対する触媒金属（ここではコバルトCo）の元素比がモル比（Co/N）で0.06であった。さらに、触媒金属に対する窒素の含有モル比率（N/Co％）は、10％以上であることが明らかとなった。このモル比率は、公知のCoTMPP電極及びCoPPy電極と比較すると明らかに高く、それぞれのモル比の5倍以上及び1.75倍に及ぶ。この結果は、CoDAPP触媒を構成する2,6-ジアミノピリジンポリマーが、配位子（配位原子）となる窒素を他のガス拡散電極に包含される電極触媒と比較して多量に包含できることを示唆している。 As shown in this table, the element ratio of nitrogen to carbon in the CoDAPP catalyst of the present invention after pickling treatment with hydrochloric acid (acid washing) was 0.12 in terms of molar ratio (N / C). Further, the elemental ratio of the catalytic metal (here, cobalt Co) to nitrogen was 0.06 in terms of molar ratio (Co / N). Furthermore, it was revealed that the molar ratio of nitrogen to catalyst metal (N / Co%) was 10% or more. This molar ratio is clearly higher than that of the known CoTMPP electrode and CoPPy electrode, and is more than 5 times and 1.75 times the respective molar ratio. This result shows that the 2,6-diaminopyridine polymer constituting the CoDAPP catalyst can contain a large amount of nitrogen as a ligand (coordinating atom) compared to the electrode catalyst included in other gas diffusion electrodes. Suggests.
＜実施例６：CoDAPP触媒中の窒素及び触媒金属の含有比率＞
　2,6-ジアミノピリジンと、コバルトのモル比が6:1、8：1、10：1となるように、モル比から2,6-ジアミノピリジンポリマー及び硝酸コバルトそれぞれの量を算出し、配合して調製したCoDAPP触媒についても、その元素組成を、同様にXPS分析法を用いて解析して、窒素（N）及びコバルト（Co）の含有比率を調べた。 <Example 6: Content ratio of nitrogen and catalytic metal in CoDAPP catalyst>
Calculate the amount of 2,6-diaminopyridine polymer and cobalt nitrate from the molar ratio so that the molar ratio of 2,6-diaminopyridine and cobalt is 6: 1, 8: 1, 10: 1 The elemental composition of the CoDAPP catalyst thus prepared was similarly analyzed using XPS analysis, and the content ratio of nitrogen (N) and cobalt (Co) was examined.
 [方法]
　CoDAPP触媒は、実施例１の実験例１に記載の方法で調製したものと、重合体金属錯体をアンモニアガス雰囲気下ではなく、窒素ガス雰囲気下で700℃にて1時間焼成し、他は実験例１と同様の方法で調製したものを用いた。元素組成の解析は、実施例５に記載の方法に準じた。 [Method]
The CoDAPP catalyst was prepared by the method described in Experimental Example 1 of Example 1, and the polymer metal complex was calcined at 700 ° C. for 1 hour in a nitrogen gas atmosphere instead of in an ammonia gas atmosphere. What was prepared by the method similar to Example 1 was used. The analysis of the element composition was in accordance with the method described in Example 5.
[結果]
　実験例１に記載の方法で調製したCoDAPP触媒のXPS分析の結果を表２に、また、前記窒素ガス雰囲気下で調製したCoDAPP触媒のXPS分析の結果を表３に示す。
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000006
 [result]
The results of XPS analysis of the CoDAPP catalyst prepared by the method described in Experimental Example 1 are shown in Table 2, and the results of XPS analysis of the CoDAPP catalyst prepared in the nitrogen gas atmosphere are shown in Table 3.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000006
　上記表で示すように、本発明のCoDAPP触媒は、炭素に対する窒素の元素比がモル比（N/C）の幅が0.11～0.15であった。また、酸洗処理（酸洗浄）後の窒素に対する触媒金属の元素比がモル比（Co/N）で0.03～0.49であった。表１の結果と合わせると、本発明の電極触媒は、炭素に対する窒素の元素比がモル比で0.1～0.2であり、かつ、酸洗浄後の窒素に対する金属の元素比がモル比で0.03以上であることが示された。 As shown in the above table, the CoDAPP catalyst of the present invention had a molar ratio of nitrogen to carbon (N / C) ranging from 0.11 to 0.15. Further, the elemental ratio of the catalyst metal to nitrogen after the pickling treatment (acid washing) was 0.03 to 0.49 in terms of molar ratio (Co / N). When combined with the results in Table 1, the electrode catalyst of the present invention has an element ratio of nitrogen to carbon of 0.1 to 0.2 in terms of molar ratio, and an element ratio of metal to nitrogen after acid cleaning of 0.03 or more in molar ratio. It was shown that there is.
　これまでの知見から、N/C比が数％（0.01～0.06）領域では、N/C比が大きいほど活性が高くなる相関が得られていたが、一方で、Nが多くなり過ぎると逆に電子共鳴の変化による導電性の低下や、分子構造の歪みが起こることが予想されていた。ところが、従来の電極触媒又はそれを含むガス拡散電極は、N/C比が最大でも0.06までしか達成し得なかった（Ozaki J., et al., Electrochem. Acta, 2010,55:1864-1871; Jaouen F., et al., J. Phys. Chem., 2003, 107: 1376-1386; Viller D., et al., J. Electrochem. Soc., 2004, 151 (9); A1507-A1515）。それ故、N/C比が0.1以上の領域では、高い活性が得られるのか、又は活性が低下するのかを実際に測定することができず、N/C比の活性のピークポイントは明らかにされていなかった。 From the knowledge so far, in the region where the N / C ratio is several percent (0.01 to 0.06), there was a correlation that the higher the N / C ratio, the higher the activity. In addition, a decrease in conductivity due to a change in electron resonance and a distortion of the molecular structure were expected to occur. However, the conventional electrocatalyst or the gas diffusion electrode including the same could only achieve a maximum N / C ratio of 0.06 (Ozaki J., et al., Electrochem. Acta, 2010, 55: 1864-1871). ; Jaouen F., et al., J. Phys. Chem., 2003, 107: 1376-1386; Viller D., et al., J. Electrochem. Soc., 2004, 151 (9); A1507-A1515) . Therefore, in the region where the N / C ratio is 0.1 or more, it is impossible to actually measure whether high activity is obtained or whether the activity is reduced, and the peak point of activity of the N / C ratio is clarified. It wasn't.
　しかし、上記表２及び３で示すように、本発明によりN/C比は、0.1を超える大幅な向上が可能となった。また、それにより、N/C比が0.1以上でも高い活性が得られるが、0.2を超えると活性がピークアウトすることも明らかになった。 However, as shown in Tables 2 and 3, according to the present invention, the N / C ratio can be significantly improved to exceed 0.1. It was also revealed that high activity was obtained even when the N / C ratio was 0.1 or more, but the activity peaked out when it exceeded 0.2.
＜実施例７：触媒活性の安定性＞
　CoDAPP電極における触媒活性の喪失を検証した
[方法]
　CoDAPP電極を用いて、5mV/sの走査速度下で500rpmの回転速度にて行った。回転工程間での触媒の喪失を防ぐために、触媒に対するナフィオンの割合を1：1にシフトした。 <Example 7: Stability of catalyst activity>
The loss of catalytic activity at the CoDAPP electrode was verified.
[Method]
Using a CoDAPP electrode, the rotation speed was 500 rpm under a scanning speed of 5 mV / s. In order to prevent the loss of catalyst between the rotation steps, the ratio of Nafion to catalyst was shifted to 1: 1.
　1回目、100回目、1000回目、2000回目及び3000回目の活性測定時の電位(カロメル電極に対する)と電流密度との関係を測定した。 The relationship between the electric potential (relative to the calomel electrode) and the current density at the first, 100th, 1000th, 2000th and 3000th activity measurements was measured.
[結果]
　図４に結果を示す。この図で示すように、本発明のCoDAPP電極は、少なくとも3000回転後まで、活性の劣化は確認できず、電極触媒として安定した触媒活性を有することが示された。 [result]
The results are shown in FIG. As shown in this figure, the CoDAPP electrode of the present invention showed no deterioration in activity until after at least 3000 revolutions, indicating that it has a stable catalytic activity as an electrode catalyst.
＜実施例８：発電能の検証＞
　各ガス拡散電極における発電能を、単槽式のMFCで検証した。 <Example 8: Verification of power generation capability>
The power generation capacity of each gas diffusion electrode was verified by a single tank type MFC.
[方法]
（１）電極
　アノードには、4cm2のグラファイトフェルトを、カソードには1cm2のカーボンペーパーからなるガス拡散電極を、それぞれ用いた。 [Method]
(1) Electrode A 4 cm 2 graphite felt was used for the anode, and a gas diffusion electrode made of 1 cm 2 carbon paper was used for the cathode.
　Chengらの方法(Cheng S, Liu H, Logan BE (2006) Increased power and coulombic efficiency of single-chamber microbial fuel cells through an improved cathode structure. Electrochem Comm 8:489-494)に準じて作製したガス拡散電極には、実施例１で調製した各電極触媒又は電極、すなわち、CoDAPP触媒、CoTMPP電極、CoPPy電極及びPt電極を、ナフィオン溶液(5%,アルドリッチ)と1:10（重量比）で混合した触媒インク又は電極インクを、カーボンペーパー上の酸素供給面となる側に4mg/cm2となるように塗布した。これによって、カーボンペーパーを導電性担体とし、CoDAPPを電極触媒とするCoDAPP電極、及びカーボンペーパーをさらなる導電性担体とするCoTMPP電極、CoPPy電極、及びPt電極が、ガス拡散電極として得られた。 Gas diffusion electrode fabricated according to the method of Cheng et al. (Cheng S, Liu H, Logan BE (2006) Increased power and coulombic efficiency of single-chamber microbial fuel cells through an improved cathode structure.Electrochem Comm 8: 489-494) The catalyst prepared by mixing each electrode catalyst or electrode prepared in Example 1, ie, CoDAPP catalyst, CoTMPP electrode, CoPPy electrode, and Pt electrode, with Nafion solution (5%, Aldrich) at 1:10 (weight ratio). Ink or electrode ink was applied at 4 mg / cm 2 on the side to be the oxygen supply surface on the carbon paper. As a result, a CoDAPP electrode using carbon paper as a conductive carrier and CoDAPP as an electrode catalyst, and a CoTMPP electrode, a CoPPy electrode, and a Pt electrode using carbon paper as a further conductive carrier were obtained as gas diffusion electrodes.
　アノードにはカーボンナノチューブで修飾したグラファイトフェルト(特願2010-257390)を用いた。また、参照極としてAg/AgCl 電極(北斗電工)を装着した。 The graphite felt modified with carbon nanotubes (Japanese Patent Application No. 2010-257390) was used for the anode. In addition, an Ag / AgCl electrode (Hokuto Denko) was attached as a reference electrode.
（２）電子供与微生物
　電子供与微生物は、日本の釜石市にて採取した水田の土に包含された微生物を用いた。 (2) Electron-donating microorganism As the electron-donating microorganism, a microorganism contained in paddy soil collected in Kamaishi City, Japan was used.
（３）電解槽の調製
　本実施例で使用した電解槽は、単槽型電解槽からなり、槽内には電子供与微生物及び栄養基質が添加された電解質溶液が収容されている。電解槽の具体的な構成は、15mLの容量を有する電解槽に、電解質溶液として、200ｍMのK2HPO4/KH2PO4（pH6.8）を含む12mLのバッファ溶液を入れ、栄養基質として、スターチ：ペプトン：フィッシュミールを3：1：１(289g COD／L、COD=化学的酸素要求量)で混合した有機混合基質を用いた。また、アノードとカソード間には、両極を短絡から防止するために、セパレーター（ペーパータオル）を挿入した。アノードとカソードを外部回路と抵抗器（10kΩ）を介して接続した。 (3) Preparation of electrolytic cell The electrolytic cell used in the present example is a single electrolytic cell, and an electrolytic solution to which an electron donating microorganism and a nutrient substrate are added is accommodated in the electrolytic cell. The specific configuration of the electrolytic cell is as follows: 12 mL of buffer solution containing 200 mM K 2 HPO 4 / KH 2 PO 4 (pH 6.8) is placed in an electrolytic cell having a capacity of 15 mL as a nutrient substrate. An organic mixed substrate in which starch: peptone: fishmeal was mixed 3: 1: 1 (289 g COD / L, COD = chemical oxygen demand) was used. Further, a separator (paper towel) was inserted between the anode and the cathode in order to prevent both electrodes from being short-circuited. The anode and cathode were connected to an external circuit via a resistor (10 kΩ).
　前記有機混合基質を一日に0.2～0.4mLで電解槽に添加した。続いて、培地を5分間窒素でパージした。500mg（湿重量）の前記水田土壌を電解槽に加え、30℃で嫌気的に培養した。その後、前記有機混合基質（300g COD/L）を電解槽に１日あたり0.2mL添加した。アノード溶液は、約50rpmで穏やかに撹拌しながら、2週間作動させ、ポテンショスタット（HA-1510、北斗電工）を用いて、様々な総電圧における電流を測定し、各ガス拡散電極における、電流／電圧（IV）カーブ及び出力カーブを得た。 The organic mixed substrate was added to the electrolytic cell at 0.2 to 0.4 mL per day. Subsequently, the medium was purged with nitrogen for 5 minutes. 500 mg (wet weight) of the paddy soil was added to the electrolytic cell and cultured anaerobically at 30 ° C. Thereafter, 0.2 mL of the organic mixed substrate (300 g COD / L) was added to the electrolytic cell per day. The anolyte solution was run for 2 weeks with gentle stirring at about 50 rpm, and using a potentiostat (HA-1510, Hokuto Denko), the current at various total voltages was measured and the current / current at each gas diffusion electrode was measured. A voltage (IV) curve and an output curve were obtained.
[結果]
　図５に結果を示す。図５Aは、各ガス拡散電極をカソードに用いた時の微生物燃料電池の電流・電圧曲線を、また図５Bは、出力をそれぞれ示している。 [result]
The results are shown in FIG. FIG. 5A shows a current / voltage curve of a microbial fuel cell when each gas diffusion electrode is used as a cathode, and FIG. 5B shows an output.
　図５Aより、CoDAPP電極を用いた場合、0.25mA/cm2の短絡電流密度が、CoTMPP電極を用いた場合、0.18mA/cm2の短絡電流密度が、CoPPy電極を用いた場合、0.14mA/cm2の短絡電流密度が、そしてPt電極を用いた場合、0.18mA/cm2の短絡電流密度が、それぞれ得られた。 From FIG. 5A, the case of using CoDAPP electrode, when the short-circuit current density 0.25 mA / cm 2 is, in the case of using the CoTMPP electrodes, the short-circuit current density of 0.18 mA / cm 2, was used CoPPy electrodes, 0.14 mA / A short circuit current density of cm 2 was obtained, and a short circuit current density of 0.18 mA / cm 2 was obtained when a Pt electrode was used.
　また、図５Bより、CoDAPP電極を用いた場合、Pmaxで0.089mW/cm2の出力密度が、CoTMPP電極を用いた場合、Pmaxで0.052mW/cm2の出力密度が、CoPPy電極を用いた場合、Pmaxで0.028mW/cm2の出力密度が、そしてPt電極を用いた場合、Pmaxで0.051mW/cm2の出力密度が、それぞれ得られた。すなわち、CoDAPP電極は、検証した4種の電極の中で最も出力が高く、Pt電極やCoTMPP電極の約1.5倍の出力が得られることが明らかとなった。 From FIG. 5B, when using a CoDAPP electrode, a Pmax output density of 0.089 mW / cm 2 is used, and when using a CoTMPP electrode, a P max output density of 0.052 mW / cm 2 is used for a CoPPy electrode. If you were, the output density of 0.028mW / cm 2 at P max is and the case of using Pt electrodes, the power density of 0.051mW / cm 2 at P max, respectively obtained. In other words, the CoDAPP electrode had the highest output among the four types of electrodes tested, and it was revealed that the output was about 1.5 times that of the Pt electrode and CoTMPP electrode.
＜実施例９：微生物燃料電池におけるカソードの活性評価＞
［方法］
　燃料電池における発電能の上昇がカソードの活性上昇によるものかを実施例７のMFCに参照極を挿入し、発電時に参照極に対してアノード、カソードの電流をポテンショスタットで任意に電位を設定しながら測定した。 <Example 9: Activity evaluation of cathode in microbial fuel cell>
[Method]
A reference electrode is inserted into the MFC of Example 7 to determine whether the increase in power generation capacity in the fuel cell is due to an increase in cathode activity, and the anode and cathode currents are arbitrarily set with a potentiostat with respect to the reference electrode during power generation. While measuring.
［結果］
　図６に結果を示す。この図には、上記の燃料電池について、Ag/AgCl電極を参照電極として用いて測定した、アノード及びカソードの分極曲線を示す。（ａ）～（ｄ）の黒塗りプロットで示される曲線がアノードの分極曲線であり、（ａ’）～（ｄ’）の白抜きプロットで示される曲線がカソードの分極曲線である。カソード分極曲線を比較すると、CoDAPP電極を用いたものが、最も高い電位で大きな電流が得られたことがわかる。一方、CoDAPP電極を用いた燃料電池においては、この電極が効率よく電子を消費したために、アノードの性能も上昇していた。本測定により、これらの効果が複合的に働き、カソード触媒としてCoDAPP触媒を用いた燃料電池の出力が向上したことが示された。 [result]
The results are shown in FIG. This figure shows the anode and cathode polarization curves of the fuel cell measured using an Ag / AgCl electrode as a reference electrode. Curves indicated by black plots (a) to (d) are anode polarization curves, and curves indicated by white plots (a ′) to (d ′) are cathode polarization curves. A comparison of the cathodic polarization curves shows that a large current was obtained at the highest potential using the CoDAPP electrode. On the other hand, in the fuel cell using the CoDAPP electrode, the efficiency of the anode was improved because the electrode consumed the electrons efficiently. These measurements showed that these effects worked in combination, and the output of the fuel cell using the CoDAPP catalyst as the cathode catalyst was improved.
＜実施例１０：各電極をカソードに用いたときのサイクリックボルタモグラム＞
　実施例７における各電極触媒をカソードに用いたMFCにおいてサイクリックボルタモグラムを測定し、微生物混合存在下における電子伝達特性を調べた。サイクリックボルタモグラムとは、電気化学セルにおいて、参照極に対して作用極の電位を連続的に変化させてその際に流れる電流を測定するものである。その際の＋と‐のピークの中点から、この反応系の酸化還元電位が求められる。 <Example 10: Cyclic voltammogram when each electrode is used as a cathode>
Cyclic voltammograms were measured by MFC using each electrocatalyst in Example 7 as a cathode, and electron transfer characteristics in the presence of a mixture of microorganisms were examined. The cyclic voltammogram is a measurement of the current flowing in the electrochemical cell by continuously changing the potential of the working electrode with respect to the reference electrode. The redox potential of this reaction system is obtained from the midpoint of the + and-peaks at that time.
[結果]
　図７に結果を示す。AはCoDAPP電極を、BはPt電極を、そしてCはCoTMPP電極をカソードに用いたときのサイクリックボルタモグラムである。実線は酸素存在下での、また破線は酸素非存在下での測定結果である。 [result]
The results are shown in FIG. A is a cyclic voltammogram when a CoDAPP electrode is used, B is a Pt electrode, and C is a CoTMPP electrode as a cathode. The solid line is the measurement result in the presence of oxygen, and the broken line is the measurement result in the absence of oxygen.
　これらの図から、CoDAPP電極を用いた場合、他の電極を用いたときよりも、包含する電極触媒の酸素還元能力が高いことが示された。 From these figures, it was shown that when the CoDAPP electrode was used, the oxygen reduction ability of the included electrode catalyst was higher than when other electrodes were used.
＜実施例１１：電極触媒の導電率＞
［方法］
　実施例１の実験例１に記載の方法で調製したCoDAPP触媒の粉末を、ダイスを用いて直径10mm、厚さ2mmの円柱状ペレットに圧粉成型した。圧粉は、30秒間10MPaの加圧で行った。作製したペレットの導電率を、ロレスタ－EP低抵抗率計（三菱化学製）と四探針プローブ（PSPプローブ、三菱化学製）を用いて測定した。 <Example 11: Conductivity of electrode catalyst>
[Method]
The CoDAPP catalyst powder prepared by the method described in Experimental Example 1 of Example 1 was compacted into cylindrical pellets having a diameter of 10 mm and a thickness of 2 mm using a die. The compacting was performed at a pressure of 10 MPa for 30 seconds. The conductivity of the prepared pellets was measured using a Loresta-EP low resistivity meter (Mitsubishi Chemical) and a four-probe probe (PSP probe, Mitsubishi Chemical).
［結果］
　導電率は、5S/cm付近を中心とする正規分布で、0.1S/cmから10S/cmの範囲であった。 [result]
The conductivity was a normal distribution centered around 5 S / cm and was in the range of 0.1 S / cm to 10 S / cm.
＜実施例１１：電極触媒の比表面積＞
［方法］
　比表面積は、窒素BET吸着法によって測定した。具体的には、まず、実施例１に記載の方法で調製したCoDAPP触媒、及びリファレンスとして20％Pt/C触媒（田中貴金属製）について10-3Paにおいて200℃で1時間加熱して真空乾燥し、サンプル内の水分や吸着物を取り除いた。前記処理をしたそれぞれの触媒について、Autosorb－3（Quantachrome社製）を用いて等温吸着線を計測し、BET法により直線変換し、比表面積を算出した。 <Example 11: Specific surface area of electrode catalyst>
[Method]
The specific surface area was measured by a nitrogen BET adsorption method. Specifically, first, the CoDAPP catalyst prepared by the method described in Example 1 and a 20% Pt / C catalyst (manufactured by Tanaka Kikinzoku) as a reference were heated at 200 ° C. for 1 hour at 10 −3 Pa and vacuum dried. Then, moisture and adsorbate in the sample were removed. For each of the above-treated catalysts, an isotherm adsorption line was measured using Autosorb-3 (manufactured by Quantachrome), and linear conversion was performed by the BET method to calculate a specific surface area.
［結果］
　図１１に結果を示す。AはCoDAPP触媒を、Bは20％Pt/C触媒をカソードに用いたときの等温吸着線である。CoDAPP触媒では比表面積は、568m2/gであった。 [result]
The results are shown in FIG. A is an isothermal adsorption line when a CoDAPP catalyst is used and B is a 20% Pt / C catalyst used as a cathode. The specific surface area of the CoDAPP catalyst was 568 m 2 / g.
　なお、本明細書で引用した全ての刊行物、特許及び特許出願は、そのまま参考として本明細書にとり入れるものとする。 It should be noted that all publications, patents and patent applications cited in this specification are incorporated herein by reference as they are.

Claims (20)

  1. 　炭素、窒素、及び触媒金属を含んだ電極触媒であって、
    　炭素に対する窒素の元素比がモル比で0.1以上0.2以下であり、かつ、
    　酸洗浄後の窒素に対する触媒金属の元素比がモル比で0.03以上であることを特徴とする前記電極触媒。     An electrocatalyst comprising carbon, nitrogen, and catalytic metal,
    The elemental ratio of nitrogen to carbon is 0.1 or more and 0.2 or less in molar ratio, and
    The electrode catalyst according to claim 1, wherein an element ratio of the catalyst metal to nitrogen after acid cleaning is 0.03 or more in terms of molar ratio.
  2. 　前記窒素に対する触媒金属の元素比がモル比で0.05以上である、請求項１記載の電極触媒。 The electrode catalyst according to claim 1, wherein an element ratio of the catalyst metal to nitrogen is 0.05 or more in terms of molar ratio.
  3. 　炭素、窒素、及び触媒金属を含んだ電極触媒であって、
    　窒素原子に配位した触媒金属の含有率が0.4モル％以上であり、かつ、
    　窒素原子の含有率が6.0モル％以上であることを特徴とする前記電極触媒。     An electrocatalyst comprising carbon, nitrogen, and catalytic metal,
    The content of the catalyst metal coordinated to the nitrogen atom is 0.4 mol% or more, and
    The said electrode catalyst characterized by the content rate of a nitrogen atom being 6.0 mol% or more.
  4. 　前記触媒金属が２種類以上の異なる金属である、請求項１～３のいずれか一項に記載の電極触媒。 The electrode catalyst according to any one of claims 1 to 3, wherein the catalyst metal is two or more different metals.
  5. 　前記触媒金属が遷移金属である、請求項１～４のいずれか一項に記載の電極触媒。 The electrode catalyst according to any one of claims 1 to 4, wherein the catalyst metal is a transition metal.
  6. 　電極触媒の導電率が0.1s/cm以上である、請求項１～５のいずれか一項に記載の電極触媒。 The electrode catalyst according to any one of claims 1 to 5, wherein the conductivity of the electrode catalyst is 0.1 s / cm or more.
  7. 　電極触媒の比表面積が500m2/g以上である、請求項１～６のいずれか一項に記載の電極触媒。 The electrode catalyst according to any one of claims 1 to 6, wherein the electrode catalyst has a specific surface area of 500 m 2 / g or more.
  8. 　ジアミノピリジン、ジアミノピリジン誘導体、トリアミノピリジン、トリアミノピリジン誘導体、テトラアミノピリジン及びテトラアミノピリジン誘導体からなる群から選択される１又は２以上をアニオン重合させて重合体を得る第一工程、
    　前記重合体と触媒金属塩との混合により前記重合体に触媒金属を配位させて重合体金属錯体を得る第二工程、及び
    　重合体金属錯体を650～800℃にて焼成して焼成金属錯体を得る第三工程
    を含む電極触媒の製造方法。     A first step of obtaining a polymer by anionic polymerization of one or more selected from the group consisting of diaminopyridine, diaminopyridine derivative, triaminopyridine, triaminopyridine derivative, tetraaminopyridine and tetraaminopyridine derivative;
    A second step of obtaining a polymer metal complex by coordinating a catalyst metal to the polymer by mixing the polymer and a catalyst metal salt; and firing the polymer metal complex at 650 to 800 ° C. The manufacturing method of the electrode catalyst including the 3rd process of obtaining.
  9. 前記第三工程を還元性ガス雰囲気下又は不活性ガス雰囲気下で行う、請求項８に記載の電極触媒の製造方法。 The method for producing an electrode catalyst according to claim 8, wherein the third step is performed in a reducing gas atmosphere or an inert gas atmosphere.
  10. 　ジアミノピリジン、ジアミノピリジン誘導体、トリアミノピリジン、トリアミノピリジン誘導体、テトラアミノピリジン及びテトラアミノピリジン誘導体からなる群から選択される１又は２以上と、触媒金属原子とのモル比が3：1～5：1となるように、前記第二工程において重合体と触媒金属塩を混合する、請求項８又は９に記載の電極触媒の製造方法。 The molar ratio of 1 or 2 or more selected from the group consisting of diaminopyridine, diaminopyridine derivative, triaminopyridine, triaminopyridine derivative, tetraaminopyridine and tetraaminopyridine derivative to the catalytic metal atom is 3: 1 to 5 : The method for producing an electrode catalyst according to claim 8 or 9, wherein the polymer and the catalyst metal salt are mixed in the second step so as to be 1.
  11. 　前記触媒金属が２種類以上の異なる金属である、請求項８～１０のいずれか一項に記載の電極触媒の製造方法。 The method for producing an electrode catalyst according to any one of claims 8 to 10, wherein the catalyst metal is two or more different metals.
  12. 　前記触媒金属が遷移金属である、請求項８～１１のいずれか一項に記載の電極触媒の製造方法。 The method for producing an electrode catalyst according to any one of claims 8 to 11, wherein the catalyst metal is a transition metal.
  13. 　前記第一工程においてジアミノピリジンとジアミノピリジン誘導体の少なくとも一方のモノマーのみを重合させる、請求項８～１２のいずれか一項に記載の電極触媒の製造方法。 The method for producing an electrode catalyst according to any one of claims 8 to 12, wherein in the first step, only at least one monomer of diaminopyridine and a diaminopyridine derivative is polymerized.
  14. 　前記ジアミノピリジンが2,6-ジアミノピリジンである、請求項８～１３のいずれか一項に記載の電極触媒の製造方法。 The method for producing an electrode catalyst according to any one of claims 8 to 13, wherein the diaminopyridine is 2,6-diaminopyridine.
  15. 　請求項８～１４のいずれか一項に記載の製造方法によって得られる電極触媒。 An electrode catalyst obtained by the production method according to any one of claims 8 to 14.
  16. 　請求項１～７及び１５のいずれか一項に記載の電極触媒を担持する導電性担体を含むガス拡散電極。 A gas diffusion electrode comprising a conductive carrier carrying the electrode catalyst according to any one of claims 1 to 7 and 15.
  17. 　前記導電性担体が炭素系物質である、請求項１６に記載のガス拡散電極。 The gas diffusion electrode according to claim 16, wherein the conductive support is a carbon-based material.
  18. 　前記ガス拡散電極が支持体をさらに含む、請求項１６又は１７に記載のガス拡散電極。 The gas diffusion electrode according to claim 16 or 17, wherein the gas diffusion electrode further comprises a support.
  19. 　請求項１６～１８のいずれか一項に記載のガス拡散電極を備えた燃料電池。 A fuel cell comprising the gas diffusion electrode according to any one of claims 16 to 18.
  20. 　燃料電池が固体高分子型燃料電池又は微生物燃料電池である、請求項１９に記載の燃料電池。 The fuel cell according to claim 19, wherein the fuel cell is a polymer electrolyte fuel cell or a microbial fuel cell.
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