WO2013129023A1 - Electrode catalyst for fuel cell, membrane electrode assembly, and fuel cell system - Google Patents

Electrode catalyst for fuel cell, membrane electrode assembly, and fuel cell system Download PDF

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WO2013129023A1
WO2013129023A1 PCT/JP2013/052299 JP2013052299W WO2013129023A1 WO 2013129023 A1 WO2013129023 A1 WO 2013129023A1 JP 2013052299 W JP2013052299 W JP 2013052299W WO 2013129023 A1 WO2013129023 A1 WO 2013129023A1
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catalyst
fuel cell
iron
oxygen reduction
carbon
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Japanese (ja)
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大剛 小野寺
鈴木　修一
水上　貴彰
純 川治
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株式会社 日立製作所
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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
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • 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
    • H01M4/96—Carbon-based electrodes
    • 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

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  • the present invention relates to a highly durable electrode catalyst for a fuel cell containing a lanthanoid as a main component, and a membrane using the fuel cell electrode catalyst.
  • the present invention relates to an electrode assembly and a fuel cell system.
  • Fuel cells that use solid polymer electrolyte membranes include direct methanol fuel cells (DMFC) that use methanol as the anode fuel, and solid polymer fuel cells that use hydrogen gas as the anode fuel (DMFC).
  • DMFC direct methanol fuel cells
  • PEFC Polymer Electrolyte Fuel Cell
  • DMFC and PEFC can operate at relatively low temperatures, and the power generation system is simple and can be downsized. Therefore, emergency power supplies for facilities, emergency power supplies for military and commercial mobile devices, laptop computers and portable music players Expected as a charger for mobile phones.
  • DMFC uses methanol as the fuel
  • PEFC uses hydrogen as the fuel.
  • the membrane electrode assembly composed of the anode catalyst layer / proton conductive film / cathode catalyst layer is sandwiched between the conductive gas diffusion layers, and the anode and The battery system is connected to an external circuit by a current collecting plate provided on the cathode electrode.
  • methanol which is a liquid fuel
  • the methanol is oxidized and converted into carbon dioxide (CO 2 ) by a chemical reaction represented by the following formula (1), and protons (H + ) and electrons ( e -) and is generated.
  • reaction of following formula (3) advances as the whole battery,
  • produces in this case can be taken out by an external circuit, and an electrical energy can be obtained.
  • Patent Document 1 discloses non-platinum-based cathode catalysts such as iron and cobalt. A fuel cell electrode based on a carbon-based catalyst containing a transition metal has been reported.
  • Non-Patent Document 1 Non-Patent Document 1
  • the present invention has been made in view of such circumstances, and an object of the present invention is to suppress a decrease in oxygen reduction activity and to provide a carbon-based fuel cell electrode catalyst excellent in durability, and the fuel cell electrode catalyst.
  • An object of the present invention is to provide a membrane electrode assembly and a fuel cell using the above.
  • the electrode catalyst for a fuel cell of the present invention capable of achieving the above object includes at least one metal species selected from the lanthanoid group, and is based on carbon containing either or both of nitrogen and boron atoms. It is characterized by that.
  • the membrane electrode assembly of the present invention is an membrane electrode assembly having an anode catalyst layer, a cathode catalyst layer, and a solid polymer electrolyte membrane disposed between the anode catalyst layer and the cathode catalyst layer.
  • the present invention is characterized by a fuel cell system using the membrane electrode assembly.
  • a carbon-based electrode catalyst for a fuel cell that suppresses a decrease in oxygen reduction activity and is excellent in durability, and a membrane electrode assembly and a fuel cell using the fuel cell electrode catalyst. Can do.
  • Non-Patent Document 1 the oxygen reduction activity of the carbon-based catalyst containing iron is improved.
  • a carbon-based catalyst containing only iron hydrogen peroxide and iron generated during the oxygen reduction reaction cause a Fenton reaction to generate radicals with strong oxidizing power. Accordingly, there is a problem that the solid polymer membrane constituting the electrode catalyst and the membrane electrode assembly is deteriorated by being oxidized, and the performance of the fuel cell system is lowered.
  • at least selected from a lanthanoid group with respect to a carbon-based catalyst containing as a main component carbon containing iron or both of nitrogen and boron atoms and iron It has been found that the durability of the electrode catalyst and membrane electrode assembly can be improved by including one type of metal species.
  • the content of lanthanoid relative to the total of iron and lanthanoid contained in the catalyst is preferably 20 at.% Or more. Further, from the viewpoint of maintaining the oxygen reduction activity at the same time, it is desirable to contain iron in a certain ratio, and the content of lanthanoid relative to the total of iron and lanthanoid contained in the catalyst is in the range of 20 at.% To 60 at.%. It is preferable that If the content of lanthanoid relative to the total of iron and lanthanoid contained in the catalyst is less than 20 at.%, The oxygen reduction activity of the catalyst is maintained, but the catalyst is remarkably deteriorated and the desired performance cannot be obtained. In addition, when the content of lanthanoid relative to the total of iron and lanthanoid contained in the catalyst is larger than 60 at.%, The oxygen reduction activity of the catalyst is decreased and desired performance can be obtained. There are no prisoners.
  • the fuel cell electrode catalyst of the present invention exhibits oxygen reduction activity, and is used as a catalyst for a cathode catalyst layer of a fuel cell membrane electrode assembly.
  • the fuel cell membrane electrode assembly of the present invention uses the fuel cell electrode catalyst of the present invention as the catalyst of the cathode catalyst layer, and is a direct methanol fuel cell, a solid polymer using hydrogen as fuel.
  • the present invention can be applied to a fuel cell such as a type fuel cell.
  • a fuel cell such as a type fuel cell.
  • limiting in particular about structures and structures other than the cathode catalyst layer of a fuel cell The structure and structure conventionally known can be applied.
  • Example 1 Iron acetate: 0.0015 mol and lanthanum nitrate: 0.0005 mol were added to a solution in which 0.5 g of a phenolic resin as a carbon-based catalyst precursor was dispersed in ethanol. Next, 0.006 mol of 1,10 phenanthroline was added and stirred. This mixed solution was dried under reduced pressure, 0.5 g of Ketjen Black EC300J as a carrier was added, and the mixture was uniformly mixed in a mortar. This mixture was uniformly placed in a quartz boat and put into a tubular electric furnace.
  • Nitrogen gas was allowed to flow into this tubular electric furnace at a rate of 100 ml / min., And in an inert atmosphere, heat treatment was performed at a heat treatment temperature of 900 ° C. to obtain a desired carbon-based non-platinum catalyst.
  • Example 2 A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that the addition amounts of iron acetate and lanthanum nitrate in Example 1 were changed to 0.001 mol of iron acetate and 0.001 mol of lanthanum nitrate, respectively. It was.
  • Example 3 A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that the addition amounts of iron acetate and lanthanum nitrate in Example 1 were changed to 0.0005 mol of iron acetate and 0.0015 mol of lanthanum nitrate, respectively. It was.
  • Example 4 A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that the amount of lanthanum nitrate added in Example 1 was changed to 0.002 mol of lanthanum nitrate.
  • Example 5 A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that 0.0005 mol of praseodymium nitrate was added instead of 0.0005 mol of lanthanum nitrate in Example 1.
  • Example 6 The amount of iron acetate in Example 1 was changed to 0.001 mol, and carbon dioxide was added in the same manner as in Example 1 except that 0.001 mol of praseodymium nitrate was added instead of 0.0005 mol of lanthanum nitrate. A non-platinum catalyst was obtained.
  • Example 7 The amount of iron acetate in Example 1 was changed to 0.0005 mol, and carbon dioxide was added in the same manner as in Example 1 except that 0.0035 mol of praseodymium nitrate was added instead of 0.0005 mol of lanthanum nitrate. A non-platinum catalyst was obtained.
  • Example 8 A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that 0.0002 mol of praseodymium nitrate was added instead of 0.0015 mol of iron acetate and 0.0005 mol of lanthanum nitrate in Example 1. .
  • Example 9 A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that 0.0005 mol of gadolinium nitrate was added instead of 0.0005 mol of lanthanum nitrate in Example 1.
  • Example 10 The addition amount of iron acetate in Example 1 was changed to 0.001 mol, and instead of 0.0005 mol of lanthanum nitrate in Example 1, 0.001 mol of gadolinium nitrate was added, and the same as in Example 1. Thus, a carbon-based non-platinum catalyst was obtained.
  • Example 1 is the same as Example 1 except that the addition amount of iron acetate in Example 1 is changed to 0.0005 mol, and 0.0035 mol of gadolinium nitrate is added instead of 0.0005 mol of lanthanum nitrate in Example 1. Thus, a carbon-based non-platinum catalyst was obtained.
  • Example 12 A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that 0.0002 mol of gadolinium nitrate was added instead of 0.0015 mol of iron acetate and 0.0005 mol of lanthanum nitrate in Example 1. .
  • Example 1 A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that the amount of iron acetate added in Example 1 was changed to 0.002 mol and lanthanum nitrate was not added.
  • composition ratio of carbon-based non-platinum catalyst The composition ratio (at.%) Of the carbon-based non-platinum catalysts obtained in Examples 1 to 12 and Comparative Example 1 was evaluated using X-ray photoelectron spectroscopy (XPS).
  • XPS X-ray photoelectron spectroscopy
  • the measurement of XPS is performed using X-ray source: Monochrome Al (tube voltage 15 kV, tube current, 15 mA), lens condition: HYBRID (analysis area: 600 ⁇ 1000 ⁇ m mouth), resolution: Pass energy: 40, scanning speed: 20 eV / min (0.1 eV step), spectrum calibration: performed under calibration conditions with a carbon 1s peak.
  • the background current was subtracted from the measured oxygen reduction current, and the current at 0.5 V was compared to evaluate the initial oxygen reduction activity before the durability test. Thereafter, 500 potential cycles from 0 V to 1.1 V were performed, and the same operation as the initial oxygen reduction activity was performed to evaluate the oxygen reduction activity after the durability test.
  • FIG. 1 shows the relationship between the iron content (at.%) And the maintenance ratio of the oxygen reduction activity with respect to the total amount of lanthanoid and iron contained in the catalyst.
  • FIG. 2 shows the relationship between the iron content (at.%) And the oxygen reduction activity with respect to the total amount of lanthanoid and iron contained in the catalyst.
  • the oxygen reduction activity is a comparison and evaluation of the oxygen reduction activity, assuming that the initial oxygen reduction activity of Comparative Example 1 which is an iron-containing carbon-based catalyst containing no lanthanoid is 1.
  • the content of the lanthanoid is preferably 25 at.% Or more, more preferably 50 at.% Or more with respect to the total of the lanthanoid and iron contained in the catalyst.
  • the content of lanthanoids lanthanum, praseodymium, and gadolinium is 20 to 55 at.% Relative to the total of lanthanoid and iron contained in the catalyst with respect to Comparative Example 1.
  • the oxygen reduction activity is from 0.99 to a maximum of 1.15, and the iron content is equivalent to the oxygen reduction activity of 100 at.% Composition. It can be seen that more oxygen reduction activity can be obtained.
  • the content of lanthanoid relative to the total amount of lanthanoid and iron contained in the catalyst is 20 to 60 at.%, More preferably 25 to 55 at.%. Is preferred.
  • lanthanoid group an example in which lanthanum, praseodymium, and gadolinium are doped in the lanthanoid group has been shown. Since the properties of each element of lanthanoid are very similar, lanthanoid groups other than lanthanum, praseodymium and gadolinium are considered to have the same effect.
  • a highly durable electrode catalyst for a cathode fuel cell can be provided while maintaining oxygen reduction activity.
  • the fuel cell which has the outstanding battery characteristic can be provided.

Abstract

Provided are a highly durable, highly active electrode catalyst for oxygen reduction that does not employ platinum group elements, said platinum group elements being extremely expensive and the reserves thereof being small, and a membrane electrode assembly and fuel cell system that employ the electrode catalyst for oxygen reduction. The electrode catalyst for a fuel cell, the main component of which is carbon containing boron and/or nitrogen atoms in addition to iron, is characterized by including at least one element selected from the lanthanide group. Specifically, the electrode catalyst is characterized by the lanthanide content in relation to the total iron and lanthanide content of the catalyst being 20-60 at%.

Description

燃料電池用電極触媒、膜電極接合体および燃料電池システムFuel cell electrode catalyst, membrane electrode assembly, and fuel cell system
　本発明は、埋蔵量が少なく、高価な白金の代替となる資源的制約の少ない炭素材料を主成分とし、ランタノイドを含む耐久性の高い燃料電池用電極触媒ならびに該燃料電池電極触媒を用いた膜電極接合体および燃料電池システムに関するものである。 The present invention relates to a highly durable electrode catalyst for a fuel cell containing a lanthanoid as a main component, and a membrane using the fuel cell electrode catalyst. The present invention relates to an electrode assembly and a fuel cell system.
　昨今の原油高に加え、中国、インドなどの急速な経済発展により、化石燃料の枯渇と二酸化炭素の排出が世界的な問題となっている。このため、現在、脱石油化に向け、燃料電池を始め、リチウムイオン電池、バイオ燃料、太陽電池などの研究開発が活発に行われている。固体高分子電解質膜を使用する燃料電池には、メタノールをアノード極燃料とする直接メタノール型燃料電池（Direct Methanol Fuel Cell：ＤＭＦＣ）と、水素ガスをアノード極燃料とする固体高分子型燃料電池（Polymer Electrolyte Fuel Cell：ＰＥＦＣ）とがある。 In addition to the recent high crude oil prices, rapid economic development in China, India and other countries has led to global problems of fossil fuel depletion and carbon dioxide emissions. For this reason, research and development of fuel cells, lithium-ion batteries, biofuels, solar cells, etc. are being actively carried out for the de-oiling. Fuel cells that use solid polymer electrolyte membranes include direct methanol fuel cells (DMFC) that use methanol as the anode fuel, and solid polymer fuel cells that use hydrogen gas as the anode fuel (DMFC). Polymer Electrolyte Fuel Cell (PEFC).
　ＤＭＦＣおよびＰＥＦＣは、比較的低温作動が可能で、発電システムも簡便で小型化が可能なことから、施設の非常用電源や、軍事、業務用の携帯機器の非常電源、ノートパソコンや携帯音楽プレーヤー、携帯電話などの充電器として期待が持たれている。 DMFC and PEFC can operate at relatively low temperatures, and the power generation system is simple and can be downsized. Therefore, emergency power supplies for facilities, emergency power supplies for military and commercial mobile devices, laptop computers and portable music players Expected as a charger for mobile phones.
　ＤＭＦＣは、燃料にメタノール、また、ＰＥＦＣでは水素を燃料に使用し、アノード触媒層／プロトン導電膜／カソード触媒層から構成される膜電極接合体を導電性のガス拡散層で挟み、アノード極およびカソード極に設けた集電板により外部回路と繋いだ電池システムである。ＤＭＦＣのアノード触媒層側に液体燃料であるメタノールを供給すると、下記式（１）に示す化学反応により、メタノールが酸化されて二酸化炭素（ＣＯ2）に変化し、プロトン（Ｈ+）と電子（ｅ-）とが発生する。
　　ＣＨ3ＯＨ＋Ｈ2Ｏ→ＣＯ2＋６Ｈ+＋６ｅ-　　　　 …（１） DMFC uses methanol as the fuel, and PEFC uses hydrogen as the fuel. The membrane electrode assembly composed of the anode catalyst layer / proton conductive film / cathode catalyst layer is sandwiched between the conductive gas diffusion layers, and the anode and The battery system is connected to an external circuit by a current collecting plate provided on the cathode electrode. When methanol, which is a liquid fuel, is supplied to the anode catalyst layer side of the DMFC, the methanol is oxidized and converted into carbon dioxide (CO 2 ) by a chemical reaction represented by the following formula (1), and protons (H + ) and electrons ( e -) and is generated.
CH 3 OH + H 2 O → CO 2 + 6H + + 6e − (1)
　この反応によって発生したプロトンと電子とは、カソード触媒層に供給される酸素ガスと下記式（２）の反応により、水（Ｈ2Ｏ）を生成する。
　　Ｏ2＋４Ｈ+＋４ｅ-→２Ｈ2Ｏ　　　　　　　　　　…（２） Protons and electrons generated by this reaction generate water (H 2 O) by the reaction of the oxygen gas supplied to the cathode catalyst layer and the following formula (2).
O 2 + 4H + + 4e − → 2H 2 O (2)
　従って、電池全体として下記式（３）の反応が進行し、この際に発生する電子を外部回路で取り出して、電気エネルギーを得ることができる。
　　ＣＨ3ＯＨ＋３／２Ｏ2→ＣＯ2＋２Ｈ2Ｏ　　　　　…（３） Therefore, reaction of following formula (3) advances as the whole battery, The electron which generate | occur | produces in this case can be taken out by an external circuit, and an electrical energy can be obtained.
CH 3 OH + 3 / 2O 2 → CO 2 + 2H 2 O (3)
　また、現在、実用触媒としてＤＭＦＣおよびＰＥＦＣの電極には、白金系触媒が使用されているが、レアメタルであり、かつ非常に高価であることから、白金使用量を削減することが必須の課題となっている。 Currently, platinum-based catalysts are used as DMFC and PEFC electrodes as practical catalysts. However, since they are rare metals and very expensive, it is essential to reduce the amount of platinum used. It has become.
　こうした問題を解決する手段として、例えば、白金系触媒粒子の粒子径を小さくし、触媒比表面積を大きくすることで、触媒グラムあたりの活性を向上、かつ触媒使用量の削減を実現する試みがなされている。 As means for solving these problems, for example, attempts are made to improve the activity per gram of catalyst and reduce the amount of catalyst used by reducing the particle diameter of the platinum-based catalyst particles and increasing the specific surface area of the catalyst. ing.
　しかしながら、触媒粒子径を小さくすることにより、触媒粒子の表面エネルギーが増大し、触媒粒子同士の凝集および粗大化が生じ易くなり、性能劣化が激しい。また、触媒粒子径が小さいことで、触媒粒子が溶出し易い問題という問題も生じる。これらの触媒は、初期性能は高いが、耐久性に乏しいため、結果的には、燃料電池のコスト削減メリットは小さく、所望の電池性能を得られなくなる問題がある。 However, by reducing the catalyst particle diameter, the surface energy of the catalyst particles increases, the catalyst particles tend to aggregate and become coarser, and the performance deterioration is severe. In addition, since the catalyst particle diameter is small, there is a problem that the catalyst particles are easily eluted. These catalysts have high initial performance but poor durability. As a result, there is a problem that the cost reduction merit of the fuel cell is small and the desired cell performance cannot be obtained.
　こうしたことから、燃料電池のコスト削減には、白金を用いない安価な触媒の開発が求められている。これに対して、窒素原子および／またはホウ素原子がドープされた炭素系触媒が酸素還元活性を示すことが知られており、例えば特許文献１には、非白金系カソード触媒として鉄やコバルトなどの遷移金属を含む炭素系触媒を基材とする燃料電池用電極が報告されている。 For this reason, development of an inexpensive catalyst that does not use platinum is required to reduce the cost of fuel cells. On the other hand, it is known that carbon-based catalysts doped with nitrogen atoms and / or boron atoms exhibit oxygen reduction activity. For example, Patent Document 1 discloses non-platinum-based cathode catalysts such as iron and cobalt. A fuel cell electrode based on a carbon-based catalyst containing a transition metal has been reported.
　また、これら遷移金属の中でも、鉄を含んだ非白金系の触媒が最も高い活性を示すことが知られている（非特許文献１）。 Of these transition metals, it is known that non-platinum-based catalysts containing iron exhibit the highest activity (Non-Patent Document 1).
特開２００４－３６２８０２号公報JP 2004-362802 A 特開２００８－２８２７２５号公報JP 2008-282725 A
　しかしながら、鉄を含む非白金系の炭素系触媒では、酸素還元反応中に発生する過酸化水素と鉄がフェントン反応（下記式（４）、（５））により非常に酸化力の強いラジカルを発生させることで、触媒や膜電極接合体を劣化させ、燃料電池システムの性能低下が引き起こすという問題がある。
　　Ｆｅ2+＋Ｈ2Ｏ2→Ｆｅ3+＋ＯＨ′＋ＯＨ-　　　　 …（４）
　　Ｆｅ3+＋Ｈ2Ｏ2→Ｆｅ2+＋ＯＯＨ′＋Ｈ+　　　　 …（５） However, in non-platinum-based carbon catalysts containing iron, hydrogen peroxide and iron generated during the oxygen reduction reaction generate radicals with very strong oxidizing power through the Fenton reaction (the following formulas (4) and (5)). By doing so, there is a problem that the catalyst and the membrane electrode assembly are deteriorated and the performance of the fuel cell system is lowered.
Fe 2+ + H 2 O 2 → Fe 3+ + OH ′ + OH − (4)
Fe 3+ + H 2 O 2 → Fe 2+ + OOH ′ + H + (5)
　この問題を解決するために、触媒中に含まれる鉄の含有量を低減させても酸素還元活性を維持でき、触媒および膜電極接合体の劣化が抑制できる炭素系触媒材料の開発が必要である。 In order to solve this problem, it is necessary to develop a carbon-based catalyst material that can maintain the oxygen reduction activity even if the iron content in the catalyst is reduced and can suppress the deterioration of the catalyst and the membrane electrode assembly. .
　本発明はこのような事情に鑑みてなされたものであり、その目的は、酸素還元活性の低下を抑制し、耐久性に優れた炭素系の燃料電池用電極触媒、並びに該燃料電池用電極触媒を用いた膜電極接合体および燃料電池を提供することにある。 The present invention has been made in view of such circumstances, and an object of the present invention is to suppress a decrease in oxygen reduction activity and to provide a carbon-based fuel cell electrode catalyst excellent in durability, and the fuel cell electrode catalyst. An object of the present invention is to provide a membrane electrode assembly and a fuel cell using the above.
　前記目的を達成し得た本発明の燃料電池用電極触媒は、ランタノイド群から選択される少なくとも１種類の金属種を含み、窒素またはホウ素原子のいずれかもしくはその両方を含む炭素を基材とすることを特徴とする。 The electrode catalyst for a fuel cell of the present invention capable of achieving the above object includes at least one metal species selected from the lanthanoid group, and is based on carbon containing either or both of nitrogen and boron atoms. It is characterized by that.
　更に、本発明の膜電極接合体は、アノード触媒層、カソード触媒層、および前記アノード触媒層と前記カソード触媒層との間に配された固体高分子電解質膜を有する膜電極接合体であって、前記カソード触媒層の触媒に、ランタノイド群から選択される少なくとも１種類の金属種を含み、窒素またはホウ素原子のいずれかもしくはその両方を含む炭素を基材とする触媒を用いたことを特徴とするものである。 Furthermore, the membrane electrode assembly of the present invention is an membrane electrode assembly having an anode catalyst layer, a cathode catalyst layer, and a solid polymer electrolyte membrane disposed between the anode catalyst layer and the cathode catalyst layer. A catalyst based on carbon containing at least one metal species selected from a lanthanoid group and containing either or both of nitrogen and boron atoms, as the catalyst of the cathode catalyst layer, To do.
　また、上記膜電極接合体を用いた燃料電池システムを特徴とするものである。 Also, the present invention is characterized by a fuel cell system using the membrane electrode assembly.
　本発明によれば、酸素還元活性の低下を抑制し、耐久性に優れた炭素系の燃料電池用電極触媒、並びに該燃料電池用電極触媒を用いた膜電極接合体および燃料電池を提供することができる。 According to the present invention, there are provided a carbon-based electrode catalyst for a fuel cell that suppresses a decrease in oxygen reduction activity and is excellent in durability, and a membrane electrode assembly and a fuel cell using the fuel cell electrode catalyst. Can do.
鉄の組成比と酸素還元活性の維持率の関係を示した図。The figure which showed the relationship between the composition ratio of iron and the maintenance rate of oxygen reduction activity. 鉄の組成比と酸素還元活性の維持率の関係を示した図。The figure which showed the relationship between the composition ratio of iron and the maintenance rate of oxygen reduction activity.
　非特許文献１に開示されている通り、鉄を含む炭素系触媒の酸素還元活性は向上する。しかしながら、鉄のみを含む炭素系触媒では、酸素還元反応中に生成する過酸化水素と鉄がフェントン反応を起こし、酸化力の強いラジカルを発生する。これによって、電極触媒および膜電極接合体を構成する固体高分子膜が酸化することで劣化し、燃料電池システムの性能低下を引き起こす問題がある。これに対して、本発明者らが鋭意検討した結果、窒素またはホウ素原子のいずれかもしくはその両方と鉄を含み、炭素を主成分とする炭素系触媒に対して、ランタノイド群から選択される少なくとも１種類の金属種を含ませることで、電極触媒および膜電極接合体の耐久性を向上できることを見出した。 As disclosed in Non-Patent Document 1, the oxygen reduction activity of the carbon-based catalyst containing iron is improved. However, in a carbon-based catalyst containing only iron, hydrogen peroxide and iron generated during the oxygen reduction reaction cause a Fenton reaction to generate radicals with strong oxidizing power. Accordingly, there is a problem that the solid polymer membrane constituting the electrode catalyst and the membrane electrode assembly is deteriorated by being oxidized, and the performance of the fuel cell system is lowered. On the other hand, as a result of intensive studies by the present inventors, at least selected from a lanthanoid group with respect to a carbon-based catalyst containing as a main component carbon containing iron or both of nitrogen and boron atoms and iron. It has been found that the durability of the electrode catalyst and membrane electrode assembly can be improved by including one type of metal species.
　本発明の燃料電池用電極触媒において、耐久性（酸素還元活性維持率）向上のために、触媒中に含まれる鉄とランタノイドの合計に対するランタノイドの含有量を２０at.％以上とするが好ましい。また、酸素還元活性も同時に維持するという観点から、鉄を一定の割合で含むことが望ましく、触媒中に含まれる鉄とランタノイドの合計に対するランタノイドの含有量を、２０at.％～６０at.％の範囲とすることが好ましい。触媒中に含まれる鉄とランタノイドの合計に対するランタノイドの含有量が２０at.％よりも小さくと触媒の酸素還元活性は維持されるものの、触媒劣化が著しく、所望の性能が得られない。また、触媒中に含まれる鉄とランタノイドの合計に対するランタノイドの含有量がランタノイドの含有量が６０at.％よりも大きくなると、逆に触媒の酸素還元活性が低下してしまい、所望の性能を得られない虜がある。 In the fuel cell electrode catalyst of the present invention, in order to improve durability (oxygen reduction activity retention rate), the content of lanthanoid relative to the total of iron and lanthanoid contained in the catalyst is preferably 20 at.% Or more. Further, from the viewpoint of maintaining the oxygen reduction activity at the same time, it is desirable to contain iron in a certain ratio, and the content of lanthanoid relative to the total of iron and lanthanoid contained in the catalyst is in the range of 20 at.% To 60 at.%. It is preferable that If the content of lanthanoid relative to the total of iron and lanthanoid contained in the catalyst is less than 20 at.%, The oxygen reduction activity of the catalyst is maintained, but the catalyst is remarkably deteriorated and the desired performance cannot be obtained. In addition, when the content of lanthanoid relative to the total of iron and lanthanoid contained in the catalyst is larger than 60 at.%, The oxygen reduction activity of the catalyst is decreased and desired performance can be obtained. There are no prisoners.
　本発明の燃料電池用電極触媒は酸素還元活性を示し、燃料電池用膜電極接合体のカソード触媒層の触媒として使用される。 The fuel cell electrode catalyst of the present invention exhibits oxygen reduction activity, and is used as a catalyst for a cathode catalyst layer of a fuel cell membrane electrode assembly.
　すなわち、本発明の燃料電池用膜電極接合体は、カソード触媒層の触媒に、本発明の燃料電池用電極触媒を用いたものであり、直接メタノール型燃料電池、水素を燃料とする固体高分子型燃料電池などの燃料電池に適用することができる。また、燃料電池のカソード触媒層以外の構成および構造については、特に制限はなく、従来から知られている構成および構造を適用することができる。 That is, the fuel cell membrane electrode assembly of the present invention uses the fuel cell electrode catalyst of the present invention as the catalyst of the cathode catalyst layer, and is a direct methanol fuel cell, a solid polymer using hydrogen as fuel. The present invention can be applied to a fuel cell such as a type fuel cell. Moreover, there is no restriction | limiting in particular about structures and structures other than the cathode catalyst layer of a fuel cell, The structure and structure conventionally known can be applied.
　以下に本発明の好適な実施の形態ついて詳細に述べる。ただし、下記実施例は、本発明を制限するものではない。 Hereinafter, preferred embodiments of the present invention will be described in detail. However, the following examples do not limit the present invention.
（実施例１）
　エタノール中に炭素系触媒前駆体であるフェノール樹脂：０.５ｇを分散させた溶液に、酢酸鉄：０.００１５モル、硝酸ランタン：０.０００５モルを添加した。次に、１，１０フェナントロリンを０.００６モル添加し攪拌した。この混合溶液を減圧乾燥し、担体であるKetjen Black EC300J：０.５ｇを加え、乳鉢中で均一に混合した。この混合物を均一に石英ボートに入れ、管状電気炉へ投入した。この管状電気炉内に窒素ガスを１００ml／min.の速度で流入させ、不活性雰囲気にした状態で、熱処理温度９００℃で熱処理を行い、所望の炭素系非白金触媒を得た。 (Example 1)
Iron acetate: 0.0015 mol and lanthanum nitrate: 0.0005 mol were added to a solution in which 0.5 g of a phenolic resin as a carbon-based catalyst precursor was dispersed in ethanol. Next, 0.006 mol of 1,10 phenanthroline was added and stirred. This mixed solution was dried under reduced pressure, 0.5 g of Ketjen Black EC300J as a carrier was added, and the mixture was uniformly mixed in a mortar. This mixture was uniformly placed in a quartz boat and put into a tubular electric furnace. Nitrogen gas was allowed to flow into this tubular electric furnace at a rate of 100 ml / min., And in an inert atmosphere, heat treatment was performed at a heat treatment temperature of 900 ° C. to obtain a desired carbon-based non-platinum catalyst.
（実施例２）
　実施例１の酢酸鉄と硝酸ランタンの添加量をそれぞれ、酢酸鉄０.００１モル、硝酸ランタン０.００１モルに変更したこと以外は、実施例１と同様の方法で炭素系非白金触媒を得た。 (Example 2)
A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that the addition amounts of iron acetate and lanthanum nitrate in Example 1 were changed to 0.001 mol of iron acetate and 0.001 mol of lanthanum nitrate, respectively. It was.
（実施例３）
　実施例１の酢酸鉄と硝酸ランタンの添加量をそれぞれ、酢酸鉄０.０００５モル、硝酸ランタン０.００１５モルに変更したこと以外は、実施例１と同様の方法で炭素系非白金触媒を得た。 (Example 3)
A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that the addition amounts of iron acetate and lanthanum nitrate in Example 1 were changed to 0.0005 mol of iron acetate and 0.0015 mol of lanthanum nitrate, respectively. It was.
（実施例４）
　実施例１の硝酸ランタンの添加量を硝酸ランタン０.００２モルに変更したこと以外は、実施例１と同様の方法で炭素系非白金触媒を得た。 (Example 4)
A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that the amount of lanthanum nitrate added in Example 1 was changed to 0.002 mol of lanthanum nitrate.
（実施例５）
　実施例１の硝酸ランタン０.０００５モルに代えて、硝酸プラセオジムを０.０００５モル添加したこと以外は、実施例１と同様の方法で炭素系非白金触媒を得た。 (Example 5)
A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that 0.0005 mol of praseodymium nitrate was added instead of 0.0005 mol of lanthanum nitrate in Example 1.
（実施例６）
　実施例１の酢酸鉄の添加量を０.００１モルに変更し、硝酸ランタン０.０００５モルに代えて、硝酸プラセオジムを０.００１モル添加したこと以外は、実施例１と同様の方法で炭素系非白金触媒を得た。 (Example 6)
The amount of iron acetate in Example 1 was changed to 0.001 mol, and carbon dioxide was added in the same manner as in Example 1 except that 0.001 mol of praseodymium nitrate was added instead of 0.0005 mol of lanthanum nitrate. A non-platinum catalyst was obtained.
（実施例７）
　実施例１の酢酸鉄の添加量を０.０００５モルに変更し、硝酸ランタン０.０００５モルに代えて、硝酸プラセオジムを０.００１５モル添加したこと以外は、実施例１と同様の方法で炭素系非白金触媒を得た。 (Example 7)
The amount of iron acetate in Example 1 was changed to 0.0005 mol, and carbon dioxide was added in the same manner as in Example 1 except that 0.0035 mol of praseodymium nitrate was added instead of 0.0005 mol of lanthanum nitrate. A non-platinum catalyst was obtained.
（実施例８）
　実施例１の酢酸鉄０.００１５モル、硝酸ランタン０.０００５モルに代えて、硝酸プラセオジムを０.００２モル添加したこと以外は、実施例１と同様の方法で炭素系非白金触媒を得た。 (Example 8)
A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that 0.0002 mol of praseodymium nitrate was added instead of 0.0015 mol of iron acetate and 0.0005 mol of lanthanum nitrate in Example 1. .
（実施例９）
　実施例１の硝酸ランタン０.０００５モルに代えて、硝酸ガドリニウムを０.０００５モル添加したこと以外は、実施例１と同様の方法で炭素系非白金触媒を得た。 Example 9
A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that 0.0005 mol of gadolinium nitrate was added instead of 0.0005 mol of lanthanum nitrate in Example 1.
（実施例１０）
　実施例１の酢酸鉄の添加量を０.００１モルに変更し、実施例１の硝酸ランタン０.０００５モルに代えて、硝酸ガドリニウムを０.００１モル添加したこと以外は、実施例１と同様の方法で炭素系非白金触媒を得た。 (Example 10)
The addition amount of iron acetate in Example 1 was changed to 0.001 mol, and instead of 0.0005 mol of lanthanum nitrate in Example 1, 0.001 mol of gadolinium nitrate was added, and the same as in Example 1. Thus, a carbon-based non-platinum catalyst was obtained.
（実施例１１）
　実施例１の酢酸鉄の添加量を０.０００５モルに変更し、実施例１の硝酸ランタン０.０００５モルに代えて、硝酸ガドリニウムを０.００１５モル添加したこと以外は、実施例１と同様の方法で炭素系非白金触媒を得た。 (Example 11)
Example 1 is the same as Example 1 except that the addition amount of iron acetate in Example 1 is changed to 0.0005 mol, and 0.0035 mol of gadolinium nitrate is added instead of 0.0005 mol of lanthanum nitrate in Example 1. Thus, a carbon-based non-platinum catalyst was obtained.
（実施例１２）
　実施例１の酢酸鉄０.００１５モル、硝酸ランタン０.０００５モルに代えて、硝酸ガドリニウムを０.００２モル添加したこと以外は、実施例１と同様の方法で炭素系非白金触媒を得た。 Example 12
A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that 0.0002 mol of gadolinium nitrate was added instead of 0.0015 mol of iron acetate and 0.0005 mol of lanthanum nitrate in Example 1. .
（比較例１）
　実施例１の酢酸鉄の添加量を０.００２モルに変更し、硝酸ランタンを添加しないこと以外は、実施例１と同様の方法で炭素系非白金触媒を得た。 (Comparative Example 1)
A carbon-based non-platinum catalyst was obtained in the same manner as in Example 1 except that the amount of iron acetate added in Example 1 was changed to 0.002 mol and lanthanum nitrate was not added.
（炭素系非白金触媒の組成比の評価）
　実施例１～１２および比較例１で得られた炭素系非白金触媒の組成比（at.％）について、Ｘ線光電子分光（ＸＰＳ）を用いて評価した。ＸＰＳの測定は、Ｘ線源：モノクロＡｌ（管電圧１５kV，管電流，１５mA）、レンズ条件：ＨＹＢＲＩＤ（分析面積：６００×１０００μｍ口）、分解能：Pass energy：４０、走査速度：２０eV／min（０.１eVステップ）、スペクトル校正：炭素１ｓピークで校正の条件で行った。 (Evaluation of composition ratio of carbon-based non-platinum catalyst)
The composition ratio (at.%) Of the carbon-based non-platinum catalysts obtained in Examples 1 to 12 and Comparative Example 1 was evaluated using X-ray photoelectron spectroscopy (XPS). The measurement of XPS is performed using X-ray source: Monochrome Al (tube voltage 15 kV, tube current, 15 mA), lens condition: HYBRID (analysis area: 600 × 1000 μm mouth), resolution: Pass energy: 40, scanning speed: 20 eV / min (0.1 eV step), spectrum calibration: performed under calibration conditions with a carbon 1s peak.
（炭素系非白金触媒の酸素還元活性および耐久性の評価）
　実施例１～１２および比較例１で得られた炭素系非白金触媒について標準的な３電極セルを組み、それらの耐久性試験前後の酸素還元活性を回転ディスク電極法により評価した。 (Evaluation of oxygen reduction activity and durability of carbon-based non-platinum catalysts)
Standard three-electrode cells were assembled for the carbon-based non-platinum catalysts obtained in Examples 1 to 12 and Comparative Example 1, and their oxygen reduction activities before and after the durability test were evaluated by the rotating disk electrode method.
　まず、純水中に分散させた炭素系非白金触媒をマイクロピペットで２０μl取り、これを回転ディスク用グラッシーカーボン電極上に塗布、乾燥した後、この上にイオン伝導性ポリマー分散液（Ａｌｄｒｉｃｈ社製「Ｎａｆｉｏｎ（登録商標）」）を５μl塗布し乾燥したものを作用極とした。また、対極には白金線、参照極には、可逆水素電極（ＲＨＥ）電極を使用し、３電極セルを構成した。 First, 20 μl of a carbon-based non-platinum catalyst dispersed in pure water is taken with a micropipette, applied onto a glassy carbon electrode for a rotating disk, dried, and then an ion conductive polymer dispersion (Aldrich) A working electrode was obtained by applying 5 μl of “Nafion (registered trademark)” and drying it. Also, a platinum wire was used as the counter electrode, and a reversible hydrogen electrode (RHE) electrode was used as the reference electrode, thereby constituting a three-electrode cell.
　まず、耐久性試験前の初期活性を評価するため、３電極セルを窒素飽和下の０.５ｍmol／ｌ硫酸水溶液中で０Ｖから１.２Ｖの電位サイクルを１０サイクル行い、触媒表面を洗浄した。次に、作用極を電極回転数１６００rpmで回転させつつ、０Ｖから１.１Ｖの電位サイクルを１サイクル行い、バックグランド電流を測定した。その後、飽和ガスを窒素から酸素に変え、酸素を飽和させた状態で、作用極を電極回転数１６００rpmで回転させつつ、０Ｖから１.１Ｖの電位サイクルを１サイクル行い、炭素系非白金触媒の酸素還元電流を測定した。測定した酸素還元電流からバックグランド電流を除し、０.５Ｖ時の電流を比較することで、耐久性試験前の初期の酸素還元活性を評価した。その後、０Ｖから１.１Ｖの電位サイクルを５００サイクル行い、初期の酸素還元活性と同様の操作を行い耐久性試験後の酸素還元活性を評価した。 First, in order to evaluate the initial activity before the durability test, 10 potential cycles from 0 V to 1.2 V were carried out in a 0.5-mole / l sulfuric acid aqueous solution under nitrogen saturation to wash the catalyst surface. Next, while rotating the working electrode at an electrode rotation speed of 1600 rpm, a potential cycle from 0 V to 1.1 V was performed for one cycle, and the background current was measured. Thereafter, the nitrogen gas is changed from nitrogen to oxygen, and the working electrode is rotated at an electrode rotation speed of 1600 rpm while the oxygen is saturated, and a potential cycle from 0 V to 1.1 V is performed for one cycle, and the carbon-based non-platinum catalyst. The oxygen reduction current was measured. The background current was subtracted from the measured oxygen reduction current, and the current at 0.5 V was compared to evaluate the initial oxygen reduction activity before the durability test. Thereafter, 500 potential cycles from 0 V to 1.1 V were performed, and the same operation as the initial oxygen reduction activity was performed to evaluate the oxygen reduction activity after the durability test.
　実施例１～１２および比較例１で得られた炭素系非白金触媒について、組成比（at.％）、初期及び５００サイクル後の酸素還元活性、並びに、５００サイクル後における酸素還元活性の活性維持率を表１に示す。なお、表１において、酸素還元活性は、初期の鉄１００％組成で製造された比較例１の酸素還元活性を１として、酸素還元活性を比較ならびに評価した。 About the carbon-based non-platinum catalysts obtained in Examples 1 to 12 and Comparative Example 1, the composition ratio (at.%), The oxygen reduction activity at the initial stage and after 500 cycles, and the activity of maintaining the oxygen reduction activity after 500 cycles The rates are shown in Table 1. In Table 1, the oxygen reduction activity was compared and evaluated with the oxygen reduction activity of Comparative Example 1 manufactured with an initial iron composition of 100% as 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　また、表１に示した評価結果に基づいて、触媒中に含まれるランタノイドおよび鉄の合計に対する鉄の含有量（at.％）と酸素還元活性の維持率の関係を図１に示す。また、表１に示した評価結果に基づいて、触媒中に含まれるランタノイドおよび鉄の合計に対する鉄の含有量（at.％）と酸素還元活性の関係を図２に示す。図１および図２においても、酸素還元活性は、ランタノイドを含まない鉄含有炭素系触媒である比較例１の初期の酸素還元活性を１として、酸素還元活性を比較ならびに評価したものである。 Also, based on the evaluation results shown in Table 1, FIG. 1 shows the relationship between the iron content (at.%) And the maintenance ratio of the oxygen reduction activity with respect to the total amount of lanthanoid and iron contained in the catalyst. Further, based on the evaluation results shown in Table 1, FIG. 2 shows the relationship between the iron content (at.%) And the oxygen reduction activity with respect to the total amount of lanthanoid and iron contained in the catalyst. Also in FIG. 1 and FIG. 2, the oxygen reduction activity is a comparison and evaluation of the oxygen reduction activity, assuming that the initial oxygen reduction activity of Comparative Example 1 which is an iron-containing carbon-based catalyst containing no lanthanoid is 1.
　表１の結果から、ランタノイドであるランタン、プラセオジムおよびガドリニウムを添加していない比較例１の活性維持率が８１％であるのに対し、ランタノイドであるランタン、プラセオジムおよびガドリニウムを添加した実施例１から１２では活性維持率が８１.２から１００％と活性維持率が向上していることが分かる。また、図１に示したように、触媒中に含まれるランタノイドおよび鉄の合計に対して、ランタノイドであるランタン、プラセオジムおよびガドリニウムともに含有量を増加させるほど活性維持率が高くなっており、鉄の含有量が１００at.％組成の比較例１に比べ、明らかに耐久性が向上していることが分かる。これらの結果から、電極触媒中にランタノイド群から選択される少なくとも１種類の金属種を添加することで、飛躍的に耐久性を向上させることができる。特に、耐久性向上には、触媒中に含まれるランタノイドおよび鉄の合計に対して、ランタノイドの含有量を２５at.％以上とすることが好ましく、５０at.％以上とすることがより好ましい。 From the results of Table 1, the activity retention rate of Comparative Example 1 in which lanthanoids lanthanum, praseodymium, and gadolinium were not added was 81%, whereas the lanthanoids lanthanum, praseodymium, and gadolinium were added. 12, it can be seen that the activity maintenance ratio is improved from 81.2 to 100%. Further, as shown in FIG. 1, the activity retention rate increases as the content of lanthanides, praseodymium and gadolinium increases with respect to the total amount of lanthanoid and iron contained in the catalyst. It can be seen that the durability is clearly improved as compared with Comparative Example 1 having a composition of 100 at. From these results, it is possible to dramatically improve the durability by adding at least one metal species selected from the lanthanoid group to the electrode catalyst. In particular, in order to improve durability, the content of the lanthanoid is preferably 25 at.% Or more, more preferably 50 at.% Or more with respect to the total of the lanthanoid and iron contained in the catalyst.
　また、表１、図２の結果から、比較例１に対して、触媒中に含まれるランタノイドおよび鉄の合計に対して、ランタノイドであるランタン、プラセオジム、ガドリニウムの含有量が２０～５５at.％の範囲となる実施例１、２、５、６、９および１０の酸素還元活性は０.９９から最大１.１５を示しており、鉄の含有量が１００at.％組成の酸素還元活性と同等かそれ以上の酸素還元活性が得られることが分かる。 Further, from the results of Table 1 and FIG. 2, the content of lanthanoids lanthanum, praseodymium, and gadolinium is 20 to 55 at.% Relative to the total of lanthanoid and iron contained in the catalyst with respect to Comparative Example 1. In Examples 1, 2, 5, 6, 9 and 10, which are within the range, the oxygen reduction activity is from 0.99 to a maximum of 1.15, and the iron content is equivalent to the oxygen reduction activity of 100 at.% Composition. It can be seen that more oxygen reduction activity can be obtained.
　耐久性向上、及び、酸素還元活性維持を両立させる観点から、触媒中に含まれるランタノイドおよび鉄の合計に対するランタノイドの含有量を、２０～６０at.％、より好ましくは２５～５５at.％とすることが好ましい。 From the viewpoint of achieving both improvement in durability and maintenance of oxygen reduction activity, the content of lanthanoid relative to the total amount of lanthanoid and iron contained in the catalyst is 20 to 60 at.%, More preferably 25 to 55 at.%. Is preferred.
　なお、本実施例では、ランタノイド群のうち、ランタン、プラセオジムおよびガドリニウムをドープした場合の例を示したが、ランタノイドは、最外殻である５ｄ軌道と６ｓ軌道の電子の詰まり方があまり変わらず、ランタノイドの各元素の性質はよく似ていることから、ランタン、プラセオジムおよびガドリニウム以外のランタノイド群でも同様の効果があると考えられる。 In the present embodiment, an example in which lanthanum, praseodymium, and gadolinium are doped in the lanthanoid group has been shown. Since the properties of each element of lanthanoid are very similar, lanthanoid groups other than lanthanum, praseodymium and gadolinium are considered to have the same effect.
　本実施例によれば、触媒に含まれる鉄の割合を低減させても、酸素還元活性を維持しつつ、耐久性の高いカソード用燃料電池用電極触媒を提供することができる。これにより、優れた電池特性を有する燃料電池を提供することができる。 According to this example, even when the ratio of iron contained in the catalyst is reduced, a highly durable electrode catalyst for a cathode fuel cell can be provided while maintaining oxygen reduction activity. Thereby, the fuel cell which has the outstanding battery characteristic can be provided.

Claims (4)

  1. 　窒素またはホウ素原子のいずれかもしくはその両方と鉄が含有された炭素を主成分とする燃料電池用電極触媒において、
    　ランタノイド群から選択される少なくとも１種類の元素を含むことを特徴とする燃料電池用電極触媒。     In an electrode catalyst for a fuel cell mainly composed of carbon containing iron containing either or both of nitrogen and boron atoms,
    A fuel cell electrode catalyst comprising at least one element selected from a lanthanoid group.
  2. 　請求項１記載の燃料電池用電極触媒において、触媒中に含まれる鉄とランタノイドの合計に対するランタノイドの含有量が２０at.％～６０at.％であることを特徴とする燃料電池用電極触媒。 2. The fuel cell electrode catalyst according to claim 1, wherein the content of lanthanoid relative to the total of iron and lanthanoid contained in the catalyst is 20 at.% To 60 at.%.
  3. 　アノード触媒層とカソード触媒層との間に固体高分子電解質膜が配置された膜電極接合体において、前記カソード触媒層に含まれる触媒が請求項１に記載の燃料電池用電極触媒であることを特徴とする膜電極接合体。 2. The fuel cell electrode catalyst according to claim 1, wherein the catalyst contained in the cathode catalyst layer is a membrane electrode assembly in which a solid polymer electrolyte membrane is disposed between the anode catalyst layer and the cathode catalyst layer. A membrane electrode assembly.
  4. 　請求項３に記載の膜電極接合体を備えることを特徴とする燃料電池。 A fuel cell comprising the membrane electrode assembly according to claim 3.
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JP2009208070A (en) * 2008-02-05 2009-09-17 Univ Of Tokyo Electrode catalyst for fuel cells, method for producing the same, and electrode for fuel cells
JP2011187423A (en) * 2010-03-11 2011-09-22 Showa Denko Kk Catalyst layer for fuel cell and application thereof
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