JP7112739B2 - Electrode material, manufacturing method thereof, electrode, membrane electrode assembly, and polymer electrolyte fuel cell - Google Patents
Electrode material, manufacturing method thereof, electrode, membrane electrode assembly, and polymer electrolyte fuel cell Download PDFInfo
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- 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
Description
本発明は、固体高分子形燃料電池の電極に好適な電極材料及びこれを使用した電極、膜電極接合体及び固体高分子形燃料電池に関する。 TECHNICAL FIELD The present invention relates to an electrode material suitable for an electrode of a polymer electrolyte fuel cell, an electrode using the same, a membrane electrode assembly, and a polymer electrolyte fuel cell.
電解質に固体高分子膜を使用した固体高分子形燃料電池（ＰＥＦＣ）は、作動温度が８０℃付近と比較的低温であるため、例えば、車載用電源、家庭用等の小規模な固定電源として導入されている。ＰＥＦＣでは、以下の電気化学反応によって電力を取り出すことができる。
アノード反応：２Ｈ2 → ４Ｈ+＋４ｅ- （反応１）
カソード反応：Ｏ2＋４Ｈ+＋４ｅ-→２Ｈ2Ｏ （反応２）
全反応 ：２Ｈ2＋Ｏ2→２Ｈ2Ｏ
A polymer electrolyte fuel cell (PEFC) that uses a solid polymer membrane as an electrolyte has a relatively low operating temperature of around 80°C. have been introduced. In PEFC, electric power can be extracted by the following electrochemical reactions.
Anode reaction: 2H 2 → 4H + +4e − (Reaction 1)
Cathodic reaction: O 2 +4H + +4e − →2H 2 O (Reaction 2)
Total reaction: 2H2 + O2 → 2H2O
ＰＥＦＣは、電解質膜と前記電解質膜の両面に積層された電極（アノード及びカソード）とを含む膜電極接合体（ＭＥＡ）と、前記膜電極接合体の両面に積層されたガス拡散層（ＧＤＬ）とからなる発電モジュールを、ガス流路が形成された２つのセパレータで挟んだ構造のセルを基本単位として構成されている。ＰＥＦＣの構成部材は、一般的に、セパレータは金属材料で形成されており、ガス拡散層は多孔質の炭素材料が使用されている。また、電極触媒層（アノード及びカソード）は、担体の表面にＰｔ等の貴金属からなる電極触媒粒子が担持された構造を有し、担体には一般的に炭素材料が使用されている（例えば、特許文献１，２）。
A PEFC consists of a membrane electrode assembly (MEA) including an electrolyte membrane and electrodes (anode and cathode) laminated on both sides of the electrolyte membrane, and a gas diffusion layer (GDL) laminated on both sides of the membrane electrode assembly. The basic unit is a cell having a structure in which a power generation module composed of is sandwiched between two separators having a gas flow path. As for the constituent members of the PEFC, the separator is generally made of a metal material, and the gas diffusion layer is made of a porous carbon material. Further, the electrode catalyst layer (anode and cathode) has a structure in which electrode catalyst particles made of a noble metal such as Pt are supported on the surface of a carrier, and a carbon material is generally used for the carrier (for example,
一方、ＰＥＦＣの膜電極接合体（ＭＥＡ）の電解質膜で使用されるナフィオン（Nafion）は酸性（ｐＨ＝０～３）であるため、ＰＥＦＣの電極材料は超強酸性条件で使用されることになる。また、通常運転しているときのセル電圧は０．４～１．０Ｖであるが、起動停止時にはセル電圧が１．５Ｖまで上昇するため、カソードでは、炭素系担体が電気化学的に酸化されてＣＯ2に分解する反応が起こり、炭素系担体が腐食されて触媒活性成分である電極触媒粒子が脱落するという問題があり、アノードにおいても運転初期などに燃料ガスが不足すると、その部分での電圧低下、あるいは濃度分極が生じて局部的に通常と反対の電位となり、炭素系担体の電気化学的酸化分解反応が起こることがある。 On the other hand, since Nafion, which is used in the electrolyte membrane of PEFC's membrane electrode assembly (MEA), is acidic (pH = 0 to 3), PEFC's electrode material is used under extremely acidic conditions. Become. In addition, the cell voltage during normal operation is 0.4 to 1.0 V, but the cell voltage rises to 1.5 V when starting and stopping, so the carbon-based support is electrochemically oxidized at the cathode. There is a problem that the carbon - based carrier is corroded and the electrode catalyst particles, which are catalytically active components, fall off. A voltage drop or concentration polarization may occur, resulting in a local potential that is opposite to the normal potential, and an electrochemical oxidative decomposition reaction of the carbonaceous support may occur.
上述した炭素系担体の腐食の問題に対し、特許文献３において、ＰＥＦＣ作動条件（強酸性、高電位）で熱力学的に安定な電子伝導性酸化物である酸化チタン（ＴｉＯ２）を担体として利用した電極材料が報告されている。この電極材料は、酸化チタン担体に起因する電気抵抗を低減させるために、繊維状炭素材料表面上に微粒子状の酸化チタン担体を高分散に担持し、当該粒子状の酸化チタン担体に電極触媒粒子が選択的に担持された構造を有している。 In response to the above-described problem of corrosion of carbon-based supports, in Patent Document 3, titanium oxide (TiO 2 ), which is an electronically conductive oxide that is thermodynamically stable under PEFC operating conditions (strongly acidic, high potential), is used as a support. The electrode materials used have been reported. In order to reduce the electrical resistance caused by the titanium oxide carrier, this electrode material has a fine particle titanium oxide carrier supported on the surface of the fibrous carbon material in a highly dispersed manner, and the particulate titanium oxide carrier contains electrode catalyst particles. has a selectively supported structure.
上述の通り、特許文献３の電極材料は、酸化チタン担体がＰＥＦＣ作動条件（強酸性、高電位）で熱力学的に安定であるため酸化腐食されることなく長期間安定であり、酸化チタン担体に担持された電極触媒粒子は実質的に炭素系導電補助材と直接接触しないため、上述した炭素腐食によって電極触媒粒子が脱落することが回避されるという利点がある。
しかしながら、ＰＥＦＣ作動条件で長期間使用されると酸化チタン担体に担持させた電極触媒粒子が凝集し、肥大化する場合があるという課題があり、この点においては改善の余地があった。
As described above, the electrode material of Patent Document 3 is stable for a long period of time without being oxidized and corroded because the titanium oxide support is thermodynamically stable under PEFC operating conditions (strong acidity, high potential). Since the electrode catalyst particles supported on the substrate do not substantially come into direct contact with the carbon-based electrically conductive auxiliary material, there is the advantage that the electrode catalyst particles are prevented from coming off due to the above-described carbon corrosion.
However, there is a problem that the electrode catalyst particles supported on the titanium oxide carrier aggregate and enlarge when used for a long period of time under PEFC operating conditions, and there is room for improvement in this respect.
かかる状況下、本発明の目的は、電極触媒粒子の凝集による肥大化が抑制され、電子伝導性酸化物に起因する電気化学的酸化への優れた耐久性と、炭素系材料に起因する優れた電子伝導性を併せ持つ電極材料、及びこれを利用した応用技術を提供することである。 Under such circumstances, an object of the present invention is to suppress enlargement due to agglomeration of electrode catalyst particles, provide excellent durability against electrochemical oxidation caused by electron conductive oxides, and exhibit excellent durability caused by carbonaceous materials. An object of the present invention is to provide an electrode material having electronic conductivity and an application technique using the same.
本発明者は、上記課題を解決すべく鋭意研究を重ねた結果、下記の発明が上記目的に合致することを見出し、本発明に至った。 As a result of earnest research to solve the above problems, the inventors of the present invention have found that the following inventions meet the above objects, and have completed the present invention.
すなわち、本発明は、以下の発明に係るものである。
＜１＞ 炭素系導電補助材と、前記炭素系導電補助材に担持された電極触媒複合体とを含み、
前記電極触媒複合体は、電極触媒粒子と、電子伝導性酸化物とを含み、
前記電子伝導性酸化物は、前記電極触媒粒子の間に存在する電極材料。
＜２＞ 前記電極触媒粒子が、粒径１ｎｍ以上１０ｎｍ以下の貴金属からなる粒子である＜１＞に記載の電極材料。
＜３＞ 前記電極触媒粒子が、ＰｔまたはＰｔを含む合金からなる粒子である＜１＞または＜２＞に記載の電極材料。
＜４＞ 前記電子伝導性酸化物が、Ｔｉ酸化物である＜１＞から＜３＞のいずれかに記載の電極材料。
＜５＞ 前記Ｔｉ酸化物が、粒子状である＜４＞に記載の電極材料。
＜６＞ 前記電極触媒複合体が、前記炭素系導電補助材の表面の少なくとも一部が露出するように前記炭素系導電補助材に担持されてなる＜１＞から＜５＞のいずれかに記載の電極材料。
＜７＞ 前記炭素系導電補助材が、高黒鉛化カーボンブラックである＜１＞から＜６＞のいずれかに記載の電極材料。
That is, the present invention relates to the following inventions.
<1> including a carbon-based conductive auxiliary material and an electrode catalyst composite supported on the carbon-based conductive auxiliary material,
The electrocatalyst composite comprises electrocatalyst particles and an electronically conductive oxide,
The electronically conductive oxide is an electrode material present between the electrocatalyst particles.
<2> The electrode material according to <1>, wherein the electrode catalyst particles are noble metal particles having a particle size of 1 nm or more and 10 nm or less.
<3> The electrode material according to <1> or <2>, wherein the electrode catalyst particles are particles made of Pt or an alloy containing Pt.
<4> The electrode material according to any one of <1> to <3>, wherein the electron conductive oxide is a Ti oxide.
<5> The electrode material according to <4>, wherein the Ti oxide is particulate.
<6> The electrode catalyst composite described in any one of <1> to <5>, wherein the electrode catalyst composite is supported on the carbon-based conductive support material such that at least part of the surface of the carbon-based conductive support material is exposed. electrode material.
<7> The electrode material according to any one of <1> to <6>, wherein the carbon-based conductive auxiliary material is highly graphitized carbon black.
また、本発明は、上記本発明の電極材料を利用した以下の発明に係るものである。
＜８＞ ＜１＞から＜７＞のいずれかに記載の電極材料とプロトン伝導性電解質材料を含み、前記導電補助材が互いに接触して導電パスを形成している電極。
＜９＞ 固体高分子電解質膜と、前記固体高分子電解質膜の一方面に接合されたカソードと、前記固体高分子電解質膜の他方面に接合されたアノードと、を有する膜電極接合体であって、前記アノードまたはカソードのいずれか一方又は両方が、＜８＞に記載の電極である膜電極接合体。
＜１０＞ ＜９＞に記載の膜電極接合体を備えてなる固体高分子形燃料電池。
＜１１＞ ＜９＞に記載の膜電極接合体を備えてなる固体高分子形水電解装置。
The present invention also relates to the following inventions using the electrode material of the present invention.
<8> An electrode comprising the electrode material according to any one of <1> to <7> and a proton-conducting electrolyte material, wherein the conductive auxiliary materials are in contact with each other to form a conductive path.
<9> A membrane electrode assembly comprising a solid polymer electrolyte membrane, a cathode bonded to one surface of the solid polymer electrolyte membrane, and an anode bonded to the other surface of the solid polymer electrolyte membrane. and a membrane electrode assembly, wherein either one or both of the anode and the cathode are the electrode according to <8>.
<10> A polymer electrolyte fuel cell comprising the membrane electrode assembly according to <9>.
<11> A polymer electrolyte water electrolysis device comprising the membrane electrode assembly according to <9>.
また、本発明は、以下の上記本発明の電極材料の製造方法に係るものである。
＜Ａ１＞ ＜１＞から＜７＞に記載の電極材料の製造方法であって、以下の工程（１）及び（２）を含む製造方法。
工程（１）：疎水性有機溶媒に、炭素系導電補助材を分散させた分散液に、電極触媒粒子前駆体のアセチルアセトナート化合物と、電子伝導性酸化物前駆体のアセチルアセトナート化合物とを溶解させ、撹拌及び溶媒の留去を行うことにより、電極触媒粒子前駆体と電子伝導性酸化物前駆体とが担持された炭素系導電補助材を得る工程
工程（２）：工程（１）で得らえた電極触媒粒子前駆体と電子伝導性酸化物前駆体とが担持された炭素系導電補助材を、不活性ガス雰囲気で熱処理することによって、電極触媒複合体を形成する工程
＜Ａ２＞ 前記炭素系導電補助材が、高黒鉛化カーボンブラックである＜Ａ１＞に記載の製造方法。
＜Ａ３＞ 工程（２）において、熱処理を異なる温度で２段階に分けて行う＜Ａ１＞または＜Ａ２＞に記載の製造方法。
＜Ａ４＞ 工程（２）において、水蒸気共存下で熱処理を行う工程を含む＜Ａ１＞から＜Ａ３＞のいずれかに記載の製造方法。
The present invention also relates to the following method for producing the electrode material of the present invention.
<A1> A method for producing the electrode material according to <1> to <7>, comprising the following steps (1) and (2).
Step (1): An acetylacetonate compound as an electrode catalyst particle precursor and an acetylacetonate compound as an electron conductive oxide precursor are added to a dispersion liquid in which a carbon-based conductive auxiliary material is dispersed in a hydrophobic organic solvent. Process step (2) for obtaining a carbon-based conductive auxiliary material supporting an electrode catalyst particle precursor and an electron conductive oxide precursor by dissolving, stirring, and distilling off the solvent: in step (1) The step of forming an electrode catalyst composite by heat-treating the obtained carbon-based conductive auxiliary material on which the electrode catalyst particle precursor and the electron conductive oxide precursor are supported in an inert gas atmosphere <A2> above. The production method according to <A1>, wherein the carbon-based conductive auxiliary material is highly graphitized carbon black.
<A3> The manufacturing method according to <A1> or <A2>, wherein in the step (2), the heat treatment is performed in two stages at different temperatures.
<A4> The production method according to any one of <A1> to <A3>, including the step of heat-treating in the presence of water vapor in step (2).
本発明によれば、電極触媒粒子の凝集による肥大化が抑制され、電子伝導性酸化物に起因する電気化学的酸化への優れた耐久性と、炭素系材料に起因する優れた電子伝導性を併せ持つ電極材料が提供される。 According to the present invention, enlargement due to agglomeration of electrode catalyst particles is suppressed, and excellent durability against electrochemical oxidation caused by electronically conductive oxides and excellent electronic conductivity caused by carbonaceous materials are achieved. Provided is a combined electrode material.
以下、本発明について例示物等を示して詳細に説明するが、本発明は以下の例示物等に限定されるものではなく、本発明の要旨を逸脱しない範囲において任意に変更して実施できる。なお、本明細書において、「～」とはその前後の数値又は物理量を含む表現として
用いるものとする。
Hereinafter, the present invention will be described in detail with reference to examples, etc., but the present invention is not limited to the following examples, etc., and can be arbitrarily modified without departing from the scope of the present invention. In this specification, "~" is used as an expression including numerical values or physical quantities before and after it.
＜１．本発明の電極材料＞
本発明は、炭素系導電補助材と、前記炭素系導電補助材に担持された電極触媒複合体とを含み、前記電極触媒複合体は、電極触媒粒子と、電子伝導性酸化物とを含み、前記電子伝導性酸化物は、前記電極触媒粒子の間に存在する電極材料（本明細書において、単に「本発明の電極材料」と記載する場合がある）に関する。
<1. Electrode material of the present invention>
The present invention includes a carbon-based conductive aid and an electrode catalyst composite supported on the carbon-based conductive aid, wherein the electrode catalyst composite includes electrode catalyst particles and an electronically conductive oxide, The electron-conducting oxide relates to an electrode material present between the electrocatalyst particles (herein sometimes simply referred to as "the electrode material of the present invention").
図１に本発明の電極材料の模式図（好適な一形態）を示す。図１に示す本発明の電極材料は、炭素系導電補助材と、これに担持された電極触媒複合体とからなる。電極触媒複合体は、微細な電極触媒粒子と、当該電極触媒粒子の間に存在する電子伝導性酸化物とからなる。このように電極触媒粒子の間の間隙を埋めるように電子伝導性酸化物が存在することによって、電極触媒粒子が凝集して肥大化することを抑制することができる。電極触媒複合体の粒子は分散して炭素系導電補助材に担持されており、炭素系導電補助材の表面の一部は露出してため、当該電極材料を用いて電極を構成した際に、前導電補助材が互いに接触して低抵抗の導電パスが形成され、電子伝導性に優れた電極となる。 FIG. 1 shows a schematic diagram (preferred form) of the electrode material of the present invention. The electrode material of the present invention shown in FIG. 1 consists of a carbon-based conductive auxiliary material and an electrode catalyst composite carried thereon. Electrocatalyst composites consist of fine electrocatalyst particles and an electronically conductive oxide present between the electrocatalyst particles. Since the electron conductive oxide is present so as to fill the gaps between the electrode catalyst particles, it is possible to suppress the aggregation and enlargement of the electrode catalyst particles. The particles of the electrode catalyst composite are dispersed and supported on the carbon-based conductive auxiliary material, and a part of the surface of the carbon-based conductive auxiliary material is exposed. The front conductive auxiliary materials come into contact with each other to form a low-resistance conductive path, resulting in an electrode with excellent electronic conductivity.
なお、図１においては、電極触媒粒子の間に存在する電子伝導性酸化物の形態は粒子であるが、電子伝導性酸化物の形態は電極触媒粒子の間に存在するのであれば粒子に限定されず、不定形であってもよい。また、電子伝導性酸化物は、結晶であっても非晶質体であってもよい。 In FIG. 1, the form of the electronically conductive oxide present between the electrode catalyst particles is particles, but the form of the electronically conductive oxide is limited to particles as long as it exists between the electrode catalyst particles. It may be indefinite shape. Also, the electronically conductive oxide may be crystalline or amorphous.
本発明の電極材料では、電極の骨格としての役割を、炭素系導電補助材が担うため、電極触媒複合体の粒径を小さくすることができる。そのため、本発明の電極材料を用いて形成した電極では、電極触媒複合体に含まれる電子伝導性酸化物に起因する電気抵抗を低減できる。 In the electrode material of the present invention, the carbon-based conductive auxiliary material serves as the skeleton of the electrode, so the particle size of the electrode catalyst composite can be reduced. Therefore, in the electrode formed using the electrode material of the present invention, the electrical resistance caused by the electronically conductive oxide contained in the electrode catalyst composite can be reduced.
このように、本発明の電極材料は、電極触媒粒子の間に存在する電子伝導性酸化物によって電極触媒粒子の凝集が抑制され、電子伝導性酸化物に起因する電気化学的酸化への優れた耐久性を有し、かつ、炭素系導電補助材に起因する優れた電子伝導性を併せ持つ。そのため、当該電極材料で形成された電極は、優れた電極性能を示すと共に、耐久性が高く、長期間発電することができる。 Thus, in the electrode material of the present invention, the aggregation of the electrode catalyst particles is suppressed by the electronically conductive oxide present between the electrode catalyst particles, and the electrochemical oxidation caused by the electronically conductive oxide is suppressed. It is durable and has excellent electronic conductivity due to the carbon-based conductive auxiliary material. Therefore, an electrode formed of the electrode material exhibits excellent electrode performance, is highly durable, and can generate power for a long period of time.
本発明の電極材料の用途は限定されないが、固体高分子形燃料電池用電極や固体高分子形水電解用電極に用いる電極材料として好適である。 Although the use of the electrode material of the present invention is not limited, it is suitable as an electrode material for use in polymer electrolyte fuel cell electrodes and polymer electrolyte water electrolysis electrodes.
以下、本発明の電極材料の構成要素について詳細に説明する。なお、以下において、本発明の電極材料を固定高分子形燃料電池（ＰＥＦＣ）用電極に使用することを想定して説明するが、本発明の電極材料はこの用途に限定されない。 The constituent elements of the electrode material of the present invention are described in detail below. The electrode material of the present invention will be described below on the assumption that it is used for a polymer electrolyte fuel cell (PEFC) electrode, but the electrode material of the present invention is not limited to this application.
［炭素系導電補助材］
本発明の電極材料において、炭素系導電補助材（以下、単に「導電補助材」と記載する場合がある。）は、本発明の電極材料に含まれ、電極を形成した際に電子伝導性を向上させる役割を有し、かつ、電極の骨格としての役割を有する。
[Carbon-based conductive auxiliary material]
In the electrode material of the present invention, the carbon-based conductive auxiliary material (hereinafter sometimes simply referred to as "conductive auxiliary material") is included in the electrode material of the present invention, and when the electrode is formed, it has electronic conductivity. It has a role to improve and has a role as a skeleton of the electrode.
本発明の電極材料における炭素系導電補助材は、二次電池や燃料電池に使用される任意の炭素系導電補助材を使用することができる。その形状や大きさは、電極の使用目的等を考慮して適宜選択できるが、燃料電池用電極等のガス拡散電極用途では、電極を形成した際の電極内の電気伝導性とガス拡散性が求められる。そのため、電気伝導性とガス拡散性とを両立させるために、炭素系導電補助材が粒子状である場合には、粒径０．０３～５００μｍであり、繊維状である場合、直径２ｎｍ～２０μｍ、全長０．０３～５００μｍ程度であることが好適である。 Any carbon-based conductive auxiliary material used in secondary batteries and fuel cells can be used as the carbon-based conductive auxiliary material in the electrode material of the present invention. The shape and size of the electrode can be appropriately selected in consideration of the purpose of use of the electrode. Desired. Therefore, in order to achieve both electrical conductivity and gas diffusibility, when the carbon-based conductive auxiliary material is particulate, the particle size is 0.03 to 500 μm, and when it is fibrous, the diameter is 2 nm to 20 μm. , the total length is preferably about 0.03 to 500 μm.
炭素系導電補助材は、特に結晶性の高い炭素材料を好適に使用することができる。当該導電補助材は、結晶性の高い炭素材料は、結晶性が低い炭素材料と比較して疎水性有機溶媒に対する分散性がよく、電極触媒複合体の前駆体化合物を固着しやすい傾向にある。 A highly crystalline carbon material can be suitably used as the carbon-based conductive auxiliary material. Carbon materials with high crystallinity have better dispersibility in hydrophobic organic solvents than carbon materials with low crystallinity, and tend to adhere the precursor compound of the electrode catalyst composite more easily.
結晶性の高い炭素材料として、カーボンナノチューブや気相成長炭素繊維等の繊維状炭素も使用できるが、特に高黒鉛化カーボンブラック（Graphitized Carbon Black, ＧＣＢ）を好適に使用できる。 As the highly crystalline carbon material, fibrous carbon such as carbon nanotubes and vapor-grown carbon fibers can be used, but highly graphitized carbon black (GCB) can be particularly preferably used.
高黒鉛化カーボンブラックは、カーボンブラックを高温黒鉛化炉で熱処理（例えば、２５００℃以上）して黒鉛化（結晶化）したものである。黒鉛化の程度は、例えば、ラマン分光法で評価することができ、例えば、ラマン分光法により求めたＲ値が１．１０以下であるものが好適に使用される。Ｒ値は、黒鉛の結晶化度を示す指標であり、１３６０ｃｍ-1及び１５８０ｃｍ-1のラマンバンドの相対強度比(I1360/I1580)である。 Highly graphitized carbon black is obtained by heat-treating (for example, 2500° C. or higher) carbon black in a high-temperature graphitization furnace to graphitize (crystallize) it. The degree of graphitization can be evaluated, for example, by Raman spectroscopy. For example, those having an R value determined by Raman spectroscopy of 1.10 or less are preferably used. The R value is an index indicating the degree of crystallinity of graphite, and is the relative intensity ratio (I 1360 /I 1580 ) of Raman bands at 1360 cm −1 and 1580 cm −1 .
高黒鉛化カーボンブラックは、二次粒子の粒径で０．０３～５００μｍ（一次粒子径１０ｎｍ～１００ｎｍ程度）である。 The highly graphitized carbon black has a secondary particle size of 0.03 to 500 μm (primary particle size of about 10 nm to 100 nm).
高黒鉛化カーボンブラックは自作品、市販品のいずれでも使用できる。好適な市販品を例示すると、キャボット社の「ＧＣＢ」シリーズ（品番：ＧＣＢ２００等）や、東海カーボン社製の「トーカブラック」シリーズ（品番：トーカブラック＃３８００等）などが挙げられる。 Highly graphitized carbon black can be used either as a self-produced product or as a commercially available product. Examples of suitable commercially available products include the "GCB" series (product number: GCB200, etc.) manufactured by Cabot Corporation and the "Toka Black" series (product number: Toka Black #3800, etc.) manufactured by Tokai Carbon Co., Ltd.
本発明で使用される炭素系導電補助材は、１種類でもよいし、または大きさ（粒径、繊維径及び繊維長さ）や結晶性等の異なる２種以上の炭素材料を任意の割合で使用してもよい。 The carbon-based conductive auxiliary material used in the present invention may be one type, or two or more types of carbon materials having different sizes (particle size, fiber diameter and fiber length) and crystallinity, etc., in an arbitrary ratio. may be used.
［電極触媒複合体］
本発明の電極材料は、電極触媒粒子と、電子伝導性酸化物とを含む電極触媒複合体を含み、当該電極触媒複合体において、電子伝導性酸化物は、前記電極触媒粒子の間に存在することに特徴がある。
[Electrocatalyst composite]
The electrode material of the present invention comprises an electrocatalyst composite comprising electrocatalyst particles and an electronically conductive oxide, wherein the electronically conductive oxide is present between the electrocatalyst particles. It is characterized by
上述の通り、従来の電子伝導性酸化物に貴金属触媒粒子が担持された電極材料では、電極として長期間使用した際に電極触媒である貴金属触媒粒子が凝集して肥大化する問題があるが、本発明の電極材料では、電極触媒粒子の間を埋めるように電子伝導性酸化物が存在する構造を有することによって電極として使用する際に電極触媒粒子が凝集して肥大化することを抑制することができる。 As described above, conventional electrode materials in which noble metal catalyst particles are supported on an electron-conductive oxide have the problem that the noble metal catalyst particles, which are electrode catalysts, agglomerate and become enlarged when used as an electrode for a long period of time. The electrode material of the present invention has a structure in which the electron conductive oxide is present so as to fill the gaps between the electrode catalyst particles, thereby suppressing the aggregation and enlargement of the electrode catalyst particles when used as an electrode. can be done.
炭素系導電補助材に担持される電極触媒複合体の形態は、本発明の目的を損なわない限り、任意であり、例えば、粒子状、島状、膜状等が挙げられる。
電極を形成した際の導電性の観点からは、電極触媒複合体が粒子状であって、当該粒子状の電極触媒複合体が導電補助材表面を完全に被覆せずに、導電補助材の表面の一部が露出され、導電補助材と他の導電補助材とが接触の直接的な接触を阻害しない程度に分散して担持されていることが好ましい。粒子状である場合の電極触媒複合体の大きさは特に限定はなく、好適には平均粒径１０～５００ｎｍである。「電極触媒複合体の平均粒径」は、電子顕微鏡像より調べられる任意の電極触媒複合体（２０個）の粒子径の平均値により得ることができる。
The form of the electrode catalyst composite supported on the carbon-based electrically conductive auxiliary material is arbitrary as long as the object of the present invention is not impaired, and examples thereof include particulate, island, and film forms.
From the viewpoint of conductivity when the electrode is formed, the electrode catalyst composite is particulate, and the particulate electrode catalyst composite does not completely cover the surface of the conductive auxiliary material, and the surface of the conductive auxiliary material is exposed, and the conductive auxiliary material and the other conductive auxiliary material are preferably dispersedly carried to the extent that direct contact is not hindered. The size of the electrode catalyst composite in the form of particles is not particularly limited, and the average particle size is preferably 10 to 500 nm. The "average particle size of the electrode catalyst composites" can be obtained from the average value of the particle sizes of arbitrary electrode catalyst composites (20 pieces) examined by an electron microscope image.
また、電極触媒複合体の担持量は、電極として十分な量の電極触媒粒子が含まれるような範囲で適宜決定される。電極触媒粒子の活性は、電極触媒金属の種類、結晶性、粒径等及び複合化させる電子伝導性酸化物の種類、結晶性、粒径等に依存するため、この点を考慮して電極触媒複合体の担持量が決定される。
電極触媒複合体の担持量は、例えば、導電補助材と電極触媒複合体の合計を１００重量％としたときに、通常、５～５０重量％であり、好ましくは１０～４０重量％である。
In addition, the amount of the electrode catalyst composite supported is appropriately determined within a range in which a sufficient amount of the electrode catalyst particles as an electrode is included. The activity of the electrode catalyst particles depends on the type, crystallinity, particle size, etc. of the electrode catalyst metal and the type, crystallinity, particle size, etc. of the electron-conductive oxide to be combined. The loading of the complex is determined.
The amount of the electrode catalyst composite supported is usually 5 to 50% by weight, preferably 10 to 40% by weight, for example, when the total of the conductive auxiliary material and the electrode catalyst composite is 100% by weight.
以下、電極触媒複合体を構成する電極触媒粒子及び電子伝導性酸化物について詳述する。 Electrocatalyst particles and electron conductive oxides constituting the electrode catalyst composite will be described in detail below.
（電極触媒粒子）
電極触媒粒子は、酸素の還元（及び水素の酸化）に対する電気化学的触媒活性を有するものであれば、貴金属系触媒、非貴金属系触媒のいずれでもよいが、好適には、Ｐｔ，Ｒｕ，Ｉｒ，Ｐｄ，Ｒｈ，Ｏｓ，Ａｕ，Ａｇ等の貴金属、及びこれらの貴金属を含む合金から選択される。なお、「貴金属を含む合金」とは「上記の貴金属のみからなる合金」と、「上記の貴金属とそれ以外の金属からなる合金で上記の貴金属を１０質量％以上含む合金」を含む。貴金属と合金化させる上記「それ以外の金属」は、特に限定されないが、Ｃｏ，Ｎｉ，Ｗ，Ｔａ，Ｎｂ，Ｓｎを好適な例として挙げることができ、これらを１種類あるいは２種類以上を使用してもよい。また、分相した状態で２種類以上の上記貴金属及び貴金属を含む合金を使用してもよい。なお、上記貴金属、及びこれらの貴金属を含む合金を以下、「電極触媒金属」と呼ぶ場合がある。
(electrode catalyst particles)
The electrode catalyst particles may be either noble metal-based catalysts or non-noble metal-based catalysts as long as they have electrochemical catalytic activity for oxygen reduction (and hydrogen oxidation). , Pd, Rh, Os, Au, Ag, etc., and alloys containing these noble metals. The term "alloy containing a noble metal" includes "alloy consisting only of the above noble metal" and "alloy consisting of the above noble metal and other metals and containing 10% by mass or more of the above noble metal". The above "other metals" to be alloyed with the noble metal are not particularly limited, but Co, Ni, W, Ta, Nb, and Sn can be mentioned as suitable examples, and one or more of these can be used. You may In addition, two or more of the noble metals and alloys containing the noble metals may be used in a phase-split state. The above noble metals and alloys containing these noble metals are hereinafter sometimes referred to as "electrode catalyst metals".
電極触媒金属の中でも、Ｐｔ及びＰｔを含む合金は、固体高分子形燃料電池の作動温度である８０℃付近の温度域において、酸素の還元（及び水素の酸化）に対する電気化学的触媒活性が高いため、特に好適に使用することができる。 Among electrode catalyst metals, Pt and alloys containing Pt have high electrochemical catalytic activity for oxygen reduction (and hydrogen oxidation) in a temperature range of around 80°C, which is the operating temperature of polymer electrolyte fuel cells. Therefore, it can be used particularly preferably.
電極触媒粒子の形状は、特に制限されず公知の電極触媒粒子と同様の形状のものが使用できる。具体的な形状として球形、楕円形、多面体、コアシェル構造等が挙げられる。また、電極触媒粒子は結晶があることが好ましいが、結晶と非晶質の混合体であってもよい。 The shape of the electrode catalyst particles is not particularly limited, and those having the same shape as known electrode catalyst particles can be used. Specific shapes include a spherical shape, an elliptical shape, a polyhedron, a core-shell structure, and the like. Further, the electrode catalyst particles preferably have crystals, but may be a mixture of crystals and amorphous.
電極触媒粒子の大きさは、小さいほど電気化学反応が進行する有効表面積が増加するため、電気化学的触媒活性が高くなる傾向がある。しかし、その大きさが小さすぎると、電気化学的反応活性が低下する。従って、電極触媒粒子の大きさは、平均粒径として、粒径１～１０ｎｍであることが好ましく、より好ましくは１．５～５ｎｍである。
なお、本発明における「電極触媒粒子の平均粒径」は、電子顕微鏡像より調べられる電極触媒粒子（２０個）の粒子径の平均値により得ることができる。電子顕微鏡像による平均粒径算出時は、微粒子の形状が、球形以外の場合は、粒子における最大長を示す方向の長さをその粒径とする。
すなわち、本発明の電極材料における電極触媒粒子の好適な態様の一つは、前記電極触媒粒子が、平均粒子径１～１０ｎｍのＰｔ及びＰｔを含む合金からなる電極触媒粒子である。
The smaller the size of the electrode catalyst particles, the greater the effective surface area where the electrochemical reaction proceeds, and thus the electrochemical catalytic activity tends to be higher. However, if the size is too small, the electrochemical reaction activity will decrease. Therefore, the average particle size of the electrode catalyst particles is preferably 1 to 10 nm, more preferably 1.5 to 5 nm.
The "average particle diameter of the electrode catalyst particles" in the present invention can be obtained from the average value of the particle diameters of the electrode catalyst particles (20 particles) examined from an electron microscope image. When the average particle size is calculated from an electron microscope image, when the shape of the fine particles is other than spherical, the length in the direction of the maximum length of the particles is taken as the particle size.
That is, one of the preferred embodiments of the electrode catalyst particles in the electrode material of the present invention is electrode catalyst particles made of Pt and an alloy containing Pt having an average particle size of 1 to 10 nm.
電極触媒粒子の量は、目的とする電極触媒活性と、複合化させる電子伝導性酸化物の種類や量を考慮して決定される。なお、電極触媒粒子の担持量は、例えば、誘導結合プラズマ発光分析（ＩＣＰ）によって調べることができる。 The amount of the electrode catalyst particles is determined in consideration of the desired electrode catalyst activity and the type and amount of the electron conductive oxide to be combined. The supported amount of the electrode catalyst particles can be examined by, for example, inductively coupled plasma emission spectroscopy (ICP).
電極触媒活性の観点からは、電極材料の全重量に対して、好ましくは０．１～６０質量％、より好ましくは０．５～３０質量％とすると、単位質量あたりの触媒活性に優れ、担持量に応じた所望の電極反応活性を得ることができる。 From the viewpoint of electrode catalyst activity, the total weight of the electrode material is preferably 0.1 to 60% by mass, more preferably 0.5 to 30% by mass. A desired electrode reaction activity can be obtained according to the amount.
（電子伝導性酸化物）
電子伝導性酸化物としては、燃料電池（特には固体高分子形燃料電池）のアノード条件、カソード条件の少なくともいずれか一方で十分な耐久性と電子伝導性を併せ持つものであればよい。なお、ＰＥＦＣのカソード条件とは、ＰＥＦＣの通常運転時のカソードにおける条件であり、温度が室温～１５０℃程度、空気等の酸素を含むガスが供給される条件（酸化雰囲気）を意味し、アノード条件とは、ＰＥＦＣの通常運転時のアノードにおける条件であり、温度が室温～１５０℃程度、水素を含む燃料ガスが供給される条件（還元雰囲気）を意味する。
(Electronically conductive oxide)
As the electron-conductive oxide, any oxide may be used as long as it has sufficient durability and electron conductivity in at least one of the anode condition and the cathode condition of the fuel cell (especially polymer electrolyte fuel cell). The cathode conditions of the PEFC are the conditions of the cathode during normal operation of the PEFC, and mean the conditions in which the temperature is about room temperature to about 150 ° C. and the gas containing oxygen such as air is supplied (oxidizing atmosphere). The conditions are the conditions at the anode during normal operation of the PEFC, and mean the conditions (reducing atmosphere) in which the temperature is about room temperature to about 150° C. and the fuel gas containing hydrogen is supplied.
電子伝導性酸化物の形態は、本発明の目的を損なわない限り、任意であり、例えば、粒子状、島状、膜状等が挙げられるが、粒子状であることが好ましい。また、電子伝導性酸化物は、結晶に限定されず、非晶質であってよく、結晶と非晶質の混合体であってもよいが、電子伝導性を高めるためには、電子伝導性酸化物は結晶であることが好ましい。
なお、本明細書において、「Ｍ酸化物」（但し、Ｍは金属元素である）と記載した場合には、Ｍ酸化物の形態は、結晶に限定されず、結晶、非晶質、結晶と非晶質の混合体のいずれも含まれる概念とする。例えば、Ｔｉ酸化物は、ＴｉＯ２結晶、酸素不定比の酸化物（「ＴｉＯｘ」と表記する）、及びこれらの混合物を含む。
The form of the electron-conducting oxide is arbitrary as long as it does not impair the object of the present invention. Further, the electronically conductive oxide is not limited to crystals, and may be amorphous or a mixture of crystals and amorphous materials. Preferably, the oxide is crystalline.
In this specification, when "M oxide" (where M is a metal element) is described, the form of M oxide is not limited to crystal, but may be crystalline, amorphous, or crystalline. The concept includes both amorphous mixtures. For example, Ti oxides include TiO2 crystals, oxygen nonstoichiometric oxides (denoted as "TiOx"), and mixtures thereof.
電子伝導性酸化物として具体的には、スズ（Ｓｎ）、モリブデン（Ｍｏ）、ニオブ（Ｎｂ）、タンタル（Ｔａ）、チタン（Ｔｉ）及びタングステン（Ｗ）から選択される１種の金属元素の酸化物を主体とする電子伝導性酸化物が挙げられる。ここで、本発明において「主体とする電子伝導性酸化物」とは、（Ａ）母体酸化物のみからなるもの、及び（Ｂ）他元素をドープされた酸化物であって、母体酸化物が８０ｍｏｌ％以上含まれるもの、を意味する。 Specifically, the electron conductive oxide is one metal element selected from tin (Sn), molybdenum (Mo), niobium (Nb), tantalum (Ta), titanium (Ti) and tungsten (W). Electronically conductive oxides mainly composed of oxides can be mentioned. Here, in the present invention, the "electron-conductive oxide as the main component" means (A) an oxide consisting only of a host oxide, and (B) an oxide doped with another element, wherein the host oxide is 80 mol % or more is included.
ドープされる元素として、具体的には、Ｓｎ，Ｔｉ，Ｓｂ，Ｎｂ，Ｔａ，Ｗ，Ｉｎ，Ｖ，Ｃｒ，Ｍｎ，Ｍｏなどが挙げられる（但し、母体酸化物と異なる元素である。）。ドープされる元素は、母体酸化物より価数が高い元素であり、例えば、母体酸化物がＴｉ酸化物の場合で例示すると、上記ドープ種元素のうち、Ｔｉ以外の元素（例えば、Ｓｂ，Ｎｂ，Ｔａ，Ｗ，Ｉｎ，Ｖ，Ｃｒ，Ｍｎ，Ｍｏなど）が選択される。この中でも、酸化チタンの電子導電性を特に高めることができる点で、ニオブ（Ｎｂ）を０．１～２０ｍｏｌ％ドープしたニオブドープ酸化チタンが特に好ましい。 Specific examples of elements to be doped include Sn, Ti, Sb, Nb, Ta, W, In, V, Cr, Mn, Mo and the like (however, the element is different from the base oxide). The element to be doped is an element having a higher valence than the base oxide. , Ta, W, In, V, Cr, Mn, Mo, etc.) are selected. Among these, niobium-doped titanium oxide obtained by doping 0.1 to 20 mol % of niobium (Nb) is particularly preferable in that the electronic conductivity of titanium oxide can be particularly enhanced.
なお、元素としてチタン（Ｔｉ）は、ＰＥＦＣのアノード条件で、酸化物であるＴｉＯ2が熱力学的に安定であり還元が起こらない。さらにＴｉ酸化物は、ＰＥＦＣのアノード条件のみならず、カソード条件でも、酸化物であるＴｉＯ2が熱力学的に安定であるため、カソードとしても使用できる。 As an element, titanium (Ti) does not undergo reduction under PEFC anode conditions because TiO 2 , which is an oxide, is thermodynamically stable. Furthermore, Ti oxide can also be used as a cathode because the oxide TiO 2 is thermodynamically stable not only under PEFC anode conditions but also under cathode conditions.
上述の通り、電極触媒複合体において、電子伝導酸化物は電極触媒粒子の間を埋めるように存在することによって、電極触媒粒子の凝集を阻害するものであり、電子伝導酸化物は、この目的を達成できるように形態で含まれていればよい。特に本発明の電極材料において、電極の骨格としての役割は導電補助材が担うことから、電子伝導性が炭素系材料と比較して小さい電子伝導酸化物は、電極触媒複合体においてできる範囲内で少量であることが好ましい。
電極触媒複合体における電子伝導酸化物の割合は、電子伝導酸化物の種類や大きさ、結晶性、並びに複合化される電極触媒粒子の種類、量や大きさに応じて適宜決定される。例えば、電極触媒粒子がＰｔ、電子伝導酸化物がＴｉ酸化物の場合では、Ｐｔ：Ｔｉ＝０．１～１０：１（モル比）である。
As described above, in the electrode catalyst composite, the electron-conducting oxide exists so as to fill the gaps between the electrode catalyst particles, thereby inhibiting aggregation of the electrode catalyst particles. It should be contained in a form that can be achieved. Especially in the electrode material of the present invention, the role of the electrode skeleton is played by the conductive auxiliary material. A small amount is preferred.
The proportion of the electron-conducting oxide in the electrode catalyst composite is appropriately determined according to the type, size, and crystallinity of the electron-conducting oxide, and the type, amount, and size of the electrode catalyst particles to be combined. For example, when the electrode catalyst particles are Pt and the electron-conducting oxide is Ti oxide, Pt:Ti=0.1 to 10:1 (molar ratio).
なお、本発明の電極材料では、電子伝導性酸化物は、電極触媒複合体において電極触媒粒子の間を充填させるものであり電子伝導性酸化物を小さくできるので、これに起因する電気抵抗を小さくできる。そのため、電子伝導性酸化物が結晶である場合のみならず、非晶質体であってもよい。
但し、電気抵抗をより小さくするためには、電子伝導性酸化物は結晶であることが好ましい。Ｔｉ酸化物の場合では、より好適には平均粒径５～４０ｎｍの結晶性のＴｉ酸化物（ＴｉＯ２）である。
In addition, in the electrode material of the present invention, the electronically conductive oxide fills the space between the electrode catalyst particles in the electrode catalyst composite, and the electronically conductive oxide can be reduced, so that the electrical resistance caused by this can be reduced. can. Therefore, the electronically conductive oxide may be amorphous as well as crystalline.
However, in order to further reduce the electric resistance, the electron conductive oxide is preferably crystalline. In the case of Ti oxide, crystalline Ti oxide (TiO 2 ) having an average particle size of 5 to 40 nm is more preferable.
＜本発明の電極材料の製造方法＞
上述した本発明の電極材料の製造方法は特に限定されず、電極材料を構成する導電補助材、電子伝導性酸化物、電極触媒粒子の種類に応じて適宜好適な方法を選択すればよい。本発明の電極材料の製造方法の好適な一例は、以下に説明する製造方法（以下、「本発明の製造方法」と称す。）である。
<Method for producing electrode material of the present invention>
The method for producing the electrode material of the present invention described above is not particularly limited, and a suitable method may be appropriately selected according to the types of the conductive auxiliary material, electron conductive oxide, and electrode catalyst particles that constitute the electrode material. A preferred example of the method for producing the electrode material of the present invention is the production method described below (hereinafter referred to as "the production method of the present invention").
すなわち、本発明の製造方法は、以下の工程（１）及び（２）を含む。
工程（１）：疎水性有機溶媒に、炭素系導電補助材を分散させた分散液に、電極触媒粒子前駆体のアセチルアセトナート化合物と、電子伝導性酸化物前駆体のアセチルアセトナート化合物とを溶解させ、撹拌及び溶媒の留去を行うことにより、電極触媒粒子前駆体と電子伝導性酸化物前駆体とが担持された炭素系導電補助材を得る工程
工程（２）：工程（１）で得らえた電極触媒粒子前駆体と電子伝導性酸化物前駆体とが担持された炭素系導電補助材を、不活性ガス雰囲気で熱処理することによって、電極触媒複合体を形成する工程
That is, the production method of the present invention includes the following steps (1) and (2).
Step (1): An acetylacetonate compound as an electrode catalyst particle precursor and an acetylacetonate compound as an electron conductive oxide precursor are added to a dispersion liquid in which a carbon-based conductive auxiliary material is dispersed in a hydrophobic organic solvent. Process step (2) for obtaining a carbon-based conductive auxiliary material supporting an electrode catalyst particle precursor and an electron conductive oxide precursor by dissolving, stirring, and distilling off the solvent: in step (1) A step of forming an electrode catalyst composite by heat-treating the obtained carbon-based conductive auxiliary material on which the electrode catalyst particle precursor and the electron conductive oxide precursor are supported in an inert gas atmosphere.
本発明の電極材料の製造方法の具体的な一例は後述する実施例で説明する方法である。 A specific example of the method for producing the electrode material of the present invention is the method described in the examples below.
本発明の製造方法の特徴は、工程（１）において、疎水性有機溶媒を使用し、電極触媒粒子と電子伝導性酸化物の前駆体化合物としてそれぞれのアセチルアセトナート化合物を使用し、これを１ステップで炭素系導電補助材に担持することによって、電極触媒粒子と電子伝導性酸化物とが複合化（ナノコンポジット化）した電極触媒複合体前駆体を得ることができる。また、アセチルアセトナート化合物は、電極触媒の性能低下の一因となる塩素や硫黄といった不純物を含まないという利点がある。 The production method of the present invention is characterized in that, in step (1), a hydrophobic organic solvent is used, acetylacetonate compounds are used as precursor compounds for the electrode catalyst particles and the electron conductive oxide, and An electrode catalyst composite precursor in which the electrode catalyst particles and the electron conductive oxide are composited (nanocomposited) can be obtained by supporting the carbon-based conductive auxiliary material in the step. In addition, the acetylacetonate compound has the advantage that it does not contain impurities such as chlorine and sulfur that contribute to deterioration of the performance of the electrode catalyst.
本発明の製造方法において、上述した結晶性の高い疎水性の炭素系導電補助材とすると、疎水性有機溶媒中での分散性が高まると共に、アセチルアセトナート化合物が付着しやすいため、電極触媒複合体が高分散に均等に担持される傾向にある。表面がグラファイト構造である炭素系導電補助材の具体例は上述した通りである。 In the production method of the present invention, when the highly crystalline hydrophobic carbon-based conductive auxiliary material described above is used, the dispersibility in the hydrophobic organic solvent increases and the acetylacetonate compound easily adheres, so the electrode catalyst composite The body tends to be carried evenly with high dispersion. Specific examples of the carbon-based conductive auxiliary material having a graphite structure on the surface are as described above.
工程（２）は、工程（１）で得らえた電極触媒粒子前駆体と電子伝導性酸化物前駆体とが担持された炭素系導電補助材を、不活性ガス雰囲気で熱処理することによって、電極触媒複合体を形成する工程である。
工程（２）において、窒素やアルゴン等の不活性雰囲気で熱処理することで電極触媒前駆体や電子伝導性酸化物前駆体とからなる電極触媒複合体前駆体が分解され、電極触媒となる金属の有する電気化学触媒作用を活性化し、電子伝導性酸化物の結晶性を高め、電子伝導性を向上させる。
In the step (2), the carbon-based conductive auxiliary material supporting the electrode catalyst particle precursor and the electron conductive oxide precursor obtained in the step (1) is heat-treated in an inert gas atmosphere to form an electrode. This is the step of forming a catalyst composite.
In the step (2), the electrode catalyst composite precursor composed of the electrode catalyst precursor and the electron conductive oxide precursor is decomposed by heat treatment in an inert atmosphere such as nitrogen or argon, and the metal that becomes the electrode catalyst is decomposed. It activates the electrochemical catalysis that it possesses, increases the crystallinity of the electronically conductive oxide, and improves the electronic conductivity.
本発明の製造方法において、工程（２）における熱処理温度は、使用する原料アセチルアセトナート化合物の分解温度を考慮して適宜決定される。この際に、熱処理を異なる温度で２段階に分けて行うことが好ましい。
例えば、Ｔｉ酸化物の場合には、熱処理温度は電極触媒がＰｔやＰｔ合金の場合、通常、１８０～４００℃、好適には２００～２５０℃である。温度が低すぎると電極触媒となる金属の活性化が不十分となり、温度が高すぎると電極触媒粒子が凝集し、有効反応表面積が小さくなりすぎる問題がある。
In the production method of the present invention, the heat treatment temperature in step (2) is appropriately determined in consideration of the decomposition temperature of the raw material acetylacetonate compound to be used. At this time, the heat treatment is preferably performed in two steps at different temperatures.
For example, in the case of Ti oxide, the heat treatment temperature is usually 180 to 400° C., preferably 200 to 250° C. when the electrode catalyst is Pt or Pt alloy. If the temperature is too low, activation of the metal used as the electrode catalyst will be insufficient, and if the temperature is too high, the electrode catalyst particles will agglomerate and the effective reaction surface area will become too small.
また、Ｔｉ酸化物等の水素を含有する還元性雰囲気中でも安定な電子伝導性酸化物の場合には、水素の存在下で熱処理を行うことができる。水素は窒素、ヘリウム、アルゴンなどの不活性気体で０．１～５０％（好適には１～１０％）に希釈されて用いられる。 Moreover, in the case of an electronically conductive oxide such as Ti oxide that is stable even in a reducing atmosphere containing hydrogen, the heat treatment can be performed in the presence of hydrogen. Hydrogen is diluted with an inert gas such as nitrogen, helium or argon to 0.1 to 50% (preferably 1 to 10%) before use.
また、工程（２）において、水蒸気共存下で熱処理を行う工程を含むことが好ましい。水蒸気共存下（加湿雰囲気）における熱処理によって、電子伝導性酸化物前駆体が十分に分解・酸化されるため、電極性能が向上する傾向にある。 Moreover, it is preferable that the step (2) includes a step of performing a heat treatment in the presence of water vapor. The heat treatment in the presence of water vapor (humidified atmosphere) sufficiently decomposes and oxidizes the electron conductive oxide precursor, which tends to improve the electrode performance.
＜２．本発明の電極材料の用途＞
（電極）
本発明の電極材料の用途は限定されないが、固体高分子形燃料電池用電極や、固体高分子形水電解装置用電極の構成材料として好適に使用できる。
本発明の電極材料のＰＥＦＣにおける電極として用いたケースについて説明すると、本発明の電極は、上述の電極材料とプロトン伝導性電解質材料を含み、前記導電補助材が互いに接触して導電パスを形成していることを特徴とする。
<2. Applications of the electrode material of the present invention>
(electrode)
Although the application of the electrode material of the present invention is not limited, it can be suitably used as a constituent material for electrodes for polymer electrolyte fuel cells and electrodes for polymer electrolyte water electrolysis devices.
To explain the case where the electrode material of the present invention is used as an electrode in PEFC, the electrode of the present invention includes the electrode material described above and a proton-conducting electrolyte material, and the conductive auxiliary materials are in contact with each other to form a conductive path. It is characterized by
本発明の電極は、上述の電極材料のみから構成されていてもよいが、通常、燃料電池の電解質に使用されるプロトン伝導性電解質材料（以下、「プロトン伝導性電解質材料」、または単に「電解質材料」と記載する場合がある。）を含む。電極材料と共に燃料電池の電極に含まれる電解質材料は、燃料電池用電解質膜に使用される電解質材料と同じであってもよく、異なってもよい。電極と電解質膜の密着性を向上させる観点から、同じものを用いることが好ましい。 The electrode of the present invention may be composed only of the electrode material described above, but usually proton-conducting electrolyte materials used in fuel cell electrolytes (hereinafter referred to as "proton-conducting electrolyte materials", or simply "electrolytes It may be described as "material".). The electrolyte material included in the fuel cell electrode together with the electrode material may be the same as or different from the electrolyte material used in the fuel cell electrolyte membrane. From the viewpoint of improving the adhesion between the electrode and the electrolyte membrane, it is preferable to use the same material.
ＰＥＦＣの電極と電解質膜とに使用される電解質材料としては、プロトン伝導性電解質材料が挙げられる。このプロトン伝導性電解質材料は、ポリマー骨格の全部または一部にフッ素原子を含むフッ素系電解質材料と、ポリマー骨格にフッ素原子を含まない炭化水素系電解質材料に大別され、この両者を電解質材料として使用することができる。 Electrolyte materials used in PEFC electrodes and electrolyte membranes include proton-conducting electrolyte materials. The proton-conducting electrolyte materials are broadly classified into fluorine-based electrolyte materials containing fluorine atoms in all or part of the polymer skeleton and hydrocarbon-based electrolyte materials not containing fluorine atoms in the polymer skeleton. can be used.
フッ素系電解質材料としては、具体的には、ナフィオン（登録商標、デュポン社製）、アシプレックス（登録商標、旭化成株式会社製）、フレミオン（登録商標、旭硝子株式会社製）などが好適な一例として挙げられる。 Specific preferred examples of fluorine-based electrolyte materials include Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Corporation), and Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.). mentioned.
炭化水素系電解質材料としては、具体的には、ポリスルホン酸、ポリスチレンスルホン酸、ポリアリールエーテルケトンスルホン酸、ポリフェニルスルホン酸、ポリベンズイミダゾールスルホン酸、ポリベンズイミダゾールホスホン酸、ポリイミドスルホン酸等のポリマーや、これらにアルキル基等の側鎖を有するポリマーが好適な一例として挙げられる。 Specific examples of hydrocarbon-based electrolyte materials include polymers such as polysulfonic acid, polystyrene sulfonic acid, polyaryletherketonesulfonic acid, polyphenylsulfonic acid, polybenzimidazole sulfonic acid, polybenzimidazole phosphonic acid, and polyimide sulfonic acid. and polymers having a side chain such as an alkyl group on these are suitable examples.
上記電極材料と電解質材料との質量比は、これらの材料を用いて形成される電極内の良好なプロトン伝導性を付与し、かつ電極内のガス拡散及び水蒸気の排出をスムーズに行えるように適宜決定すればよい。ただし、電極材料に混合する電解質材料の量が多すぎるとプロトン伝導性はよくなるが、ガスの拡散性は低下する。逆に混合する電解質材料の量が少なすぎるとガス拡散性はよくなるが、プロトン伝導性は低下する。そのため、上記電極材料に対する電解質材料の質量比率は、１０～５０質量％が好適な範囲である。この質量比率が１０質量％より小さい場合は、プロトン伝導性を有する材料の連続性が悪くなり、燃料電池用電極として十分なプロトン伝導性が確保できない。逆に５０質量％より大きい場合は電極材料の連続性が悪くなり、燃料電池用電極として十分な電子伝導性を有することができなくなる場合がある。さらには電極内部でのガス（酸素、水素、水蒸気）の拡散性が低下する場合がある。 The mass ratio of the electrode material and the electrolyte material is appropriately adjusted so as to impart good proton conductivity in the electrode formed using these materials, and to allow smooth gas diffusion and water vapor discharge in the electrode. You just have to decide. However, if the amount of the electrolyte material mixed with the electrode material is too large, the proton conductivity will improve, but the gas diffusivity will decrease. Conversely, if the amount of the electrolyte material to be mixed is too small, the gas diffusibility will improve, but the proton conductivity will decrease. Therefore, the mass ratio of the electrolyte material to the electrode material is preferably in the range of 10 to 50 mass %. If this mass ratio is less than 10% by mass, the continuity of the material having proton conductivity deteriorates, and sufficient proton conductivity as a fuel cell electrode cannot be ensured. Conversely, if it is more than 50% by mass, the continuity of the electrode material deteriorates, and it may not be possible to have sufficient electronic conductivity as a fuel cell electrode. Furthermore, the diffusibility of gases (oxygen, hydrogen, water vapor) inside the electrode may decrease.
本発明の燃料電池用電極は、上述の電極材料やプロトン伝導性材料以外の成分を含んでいてもよい。例えば、上述の電極材料に含まれる導電補助材以外の導電補助材（以下、「他の導電補助材」と記載する。）を含んでいてもよい。他の導電補助材を含むことにより、電極材料をつなぐ導電パスが増加し、電極全体としての導電性が向上する場合がある。他の導電補助材としては、上述した導電補助材である繊維状炭素及び鎖状連結炭素粒子でもよいし（但し、電子伝導性酸化物や電極触媒粒子は担持されていないもの）、カーボンブラック、活性炭など通常の粒子状炭素でもよい。 The fuel cell electrode of the present invention may contain components other than the above electrode materials and proton conductive materials. For example, a conductive auxiliary material other than the conductive auxiliary material contained in the above-described electrode material (hereinafter referred to as "another conductive auxiliary material") may be included. By including other conductive auxiliary materials, the number of conductive paths connecting electrode materials increases, and the conductivity of the electrode as a whole may be improved. Other conductive auxiliary materials may be fibrous carbon and chain-linked carbon particles, which are the conductive auxiliary materials described above (provided that electron conductive oxides and electrode catalyst particles are not supported), carbon black, Ordinary particulate carbon such as activated carbon may also be used.
なお、本発明の電極材料を含む燃料電池用電極として、ＰＥＦＣ用電極について説明したが、ＰＥＦＣ以外にもアルカリ形燃料電池、リン酸形燃料電池などの各種燃料電池における電極として用いることができる。また、ＰＥＦＣと同様な高分子電解質膜を使用した水の電解装置用の電極としても好適に使用することができる。 Although the PEFC electrode has been described as a fuel cell electrode containing the electrode material of the present invention, it can be used as an electrode in various fuel cells other than PEFC, such as an alkaline fuel cell and a phosphoric acid fuel cell. It can also be suitably used as an electrode for a water electrolysis device using a polymer electrolyte membrane similar to PEFC.
（膜電極接合体）
本発明の電極材料を用いた電極は、固体高分子形燃料電池や固体高分子形水電解装置に用いる膜電極接合体（ＭＥＡ）に好適に使用することができる。
すなわち、本発明の膜電極接合体は、固体高分子電解質膜と、前記固体高分子電解質膜の一方面に接合されたカソードと、前記固体高分子電解質膜の他方面に接合されたアノードと、を有する膜電極接合体であって、前記カソードとアノードの少なくとも一方が、上記本発明の電極であることを特徴とする。
本発明の膜電極接合体における本発明の電極以外の構成は、従来公知の構成を適用させることができる。
(Membrane electrode assembly)
An electrode using the electrode material of the present invention can be suitably used for a membrane electrode assembly (MEA) used in a polymer electrolyte fuel cell or a polymer electrolyte water electrolysis device.
That is, the membrane electrode assembly of the present invention comprises a solid polymer electrolyte membrane, a cathode bonded to one surface of the solid polymer electrolyte membrane, an anode bonded to the other surface of the solid polymer electrolyte membrane, wherein at least one of the cathode and the anode is the electrode of the present invention.
Conventionally known configurations can be applied to the configuration other than the electrodes of the present invention in the membrane electrode assembly of the present invention.
（固体高分子形燃料電池）
本発明の固体高分子形燃料電池（単セル）は、本発明の膜電極接合体を備えてなり、通常、膜電極接合体をガス流路が形成されたセパレータで挟持した構造を有する。
本発明の固体高分子形燃料電池において、本発明の膜電極接合体以外の構成要素は、公知の固体高分子形燃料電池と同様であるため、詳細な説明を省略する。
実際には、本発明の固体高分子形燃料電池（単セル）が発電性能に応じた基数だけ積層された燃料電池スタックが形成され、ガス供給装置、冷却装置などその他付随する装置を組み立てることにより使用される。
(Polymer electrolyte fuel cell)
The polymer electrolyte fuel cell (single cell) of the present invention comprises the membrane electrode assembly of the present invention, and generally has a structure in which the membrane electrode assembly is sandwiched between separators having gas flow paths formed therein.
In the polymer electrolyte fuel cell of the present invention, the constituent elements other than the membrane electrode assembly of the present invention are the same as those of known polymer electrolyte fuel cells, and detailed description thereof will be omitted.
In practice, a fuel cell stack is formed in which polymer electrolyte fuel cells (single cells) of the present invention are stacked in a number corresponding to the power generation performance, and a gas supply device, a cooling device, and other accompanying devices are assembled. used.
以下に実施例を挙げて本発明をより具体的に説明するが、本発明はこれらに限定される
ものではない。なお、以下の実施例の説明において、高黒鉛化カーボンブラックを「ＧＣＢ」と表記し、Ｔｉ酸化物を「ＴｉＯｘ」と表記し、ＰｔとＴｉ酸化物とからなる電極触媒複合体を「Ｐｔ－ＴｉＯｘ」、Ｐｔ－ＴｉＯｘを担持したＧＣＢを「Ｐｔ－ＴｉＯｘ/ＧＣＢ」と記載する場合がある。
EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these. In the following description of the examples, highly graphitized carbon black is denoted as "GCB", Ti oxide is denoted as "TiOx", and an electrode catalyst composite composed of Pt and Ti oxide is denoted as "Pt- TiOx", and Pt--TiOx-supported GCB may be described as "Pt--TiOx/GCB."
１．電極材料の作製
実施例の電極材料として、以下の実施例１～４の電極材料を製造した。
1. Preparation of Electrode Materials Electrode materials of Examples 1 to 4 below were prepared as electrode materials of Examples.
使用した導電補助材、貴金属触媒前駆体、Ｔｉ前駆体は以下の通りである。
＜導電補助材＞
導電補助材として、高黒鉛化カーボンブラック（ＧＣＢ）（キャボット社製、ＧＣＢ２００）を使用した。
＜貴金属触媒前駆体＞
貴金属触媒前駆体として、Ｐｔアセチルアセトナート（Platinum(II) acetylacetonate，97%,Sigma Aldrich）（以下、「Pt（acac)2」と記載する場合がある。）を使用した。
＜電子伝導性酸化物前駆体＞
電子伝導性酸化物前駆体として、Ｔｉアセチルアセトナート（Titanium diisopropoxide bis(acetylacetonate)，75wt.% in isopropanol,Sigma Aldrich）（以下、「Ti（acac)2OiPr2」と記載する場合がある。）を使用した。
The conductive auxiliary material, noble metal catalyst precursor, and Ti precursor used are as follows.
<Conductive auxiliary material>
Highly graphitized carbon black (GCB) (GCB200, manufactured by Cabot Corporation) was used as a conductive auxiliary material.
<Noble metal catalyst precursor>
As a noble metal catalyst precursor, Pt acetylacetonate (Platinum(II) acetylacetonate, 97%, Sigma Aldrich) (hereinafter sometimes referred to as "Pt(acac) 2 ") was used.
<Electron-Conductive Oxide Precursor>
As an electron conductive oxide precursor, Ti acetylacetonate (Titanium diisopropoxide bis(acetylacetonate), 75 wt.% in isopropanol, Sigma Aldrich) (hereinafter sometimes referred to as "Ti ( acac) 2OiPr2 "). It was used.
＜実施例１＞
工程（１）
まず、導電補助材であるＧＣＢ（２０１．５ｍｇ）をナスフラスコに入れ、これにアセトン（３０ｍＬ)を加え、超音波ホモジナイザーで撹拌し、ＧＣＢの分散液を得た。得られたＧＣＢ分散液に、Ｐｔアセチルアセトナート（９１．９ｍｇ）を加え、次いで、イソプロパノールに溶解されたＴｉアセチルアセトナート（１１４μＬ）とを加えて十分に撹拌し溶解させた。Ｐｔ前駆体とＴｉ酸化物前駆体の仕込み量は、電極材料全体に対する担持量としてＰｔを１７．７ｗｔ％、Ｔｉを４．３ｗｔ％となるようにした。なお、当該仕込み量でＰｔ：Ｔｉ（ｍｏｌ比）＝１：１である。
次いで、試料が入ったナスフラスコを減圧機能と回転機能が備わったロータリーエバポレータにセットし、氷冷しながら、溶媒が全て揮発するまで減圧しながら超音波撹拌を行い、粉末（Ｐｔ前駆体とＴｉ酸化物前駆体とを含む電極触媒複合体前駆体を担持したＧＣＢ）を得た。
<Example 1>
Step (1)
First, GCB (201.5 mg) as a conductive auxiliary material was placed in an eggplant flask, acetone (30 mL) was added thereto, and the mixture was stirred with an ultrasonic homogenizer to obtain a dispersion of GCB. To the resulting GCB dispersion, Pt acetylacetonate (91.9 mg) was added, followed by Ti acetylacetonate (114 μL) dissolved in isopropanol and thoroughly stirred to dissolve. The amounts of the Pt precursor and the Ti oxide precursor charged were such that the supported amounts of Pt and Ti with respect to the entire electrode material were 17.7 wt % and 4.3 wt %, respectively. In addition, Pt:Ti (molar ratio)=1:1 at the charged amount.
Next, the eggplant flask containing the sample is set in a rotary evaporator equipped with a decompression function and a rotation function, and while cooling with ice, ultrasonic stirring is performed while decompressing until all the solvent is volatilized, powder (Pt precursor and Ti A GCB supporting an electrode catalyst composite precursor containing an oxide precursor was obtained.
工程（２）
工程（１）で得られた粉末を、Ｎ2雰囲気下で、昇温速度１℃/分、２１０℃で３時間保持、２４０℃で３時間保持の条件で熱処理（還元処理）を施すことで実施例１の電極材料を得た。
Step (2)
The powder obtained in step (1) is subjected to heat treatment (reduction treatment) in a N2 atmosphere at a heating rate of 1 ° C./min, held at 210 ° C. for 3 hours, and held at 240 ° C. for 3 hours. An electrode material of Example 1 was obtained.
＜実施例２＞
実施例１の電極材料の製造方法の工程（２）において、Ｎ2雰囲気下で、２４０℃で３時間保持したのちに、０．６％加湿Ｎ２で３０分保持した以外は、実施例１と同様にして実施例２の電極材料を得た。
<Example 2>
Example 1 except that in step (2) of the method for producing the electrode material of Example 1, the temperature was maintained at 240°C for 3 hours in a N2 atmosphere and then 0.6% humidified N2 was maintained for 30 minutes. An electrode material of Example 2 was obtained in the same manner as above.
＜実施例３＞
実施例１の電極材料の製造方法の工程（２）において、Ｎ2雰囲気下で、２４０℃で３時間保持したのちに、３％加湿Ｎ２で３０分保持した以外は、実施例１と同様にして実施例３の電極材料を得た。
<Example 3>
Same as Example 1, except that in step (2) of the method for producing the electrode material of Example 1, the temperature was maintained at 240°C for 3 hours in a N2 atmosphere, and then the temperature was maintained at 3% humidified N2 for 30 minutes. Then, an electrode material of Example 3 was obtained.
＜実施例４＞
実施例１の電極材料の製造方法の工程（１）において、Ｐｔ前駆体とＴｉ酸化物前駆体の仕込み量を、電極材料形成後の担持量としてＰｔを２０．３ｗｔ％、Ｔｉを１．７ｗｔ％となるようにし（Ｐｔ：Ｔｉ（ｍｏｌ比）＝３：１）、工程（２）において、Ｎ2雰囲気下で、２４０℃で３時間保持したのちに、３％加湿Ｎ２で３０分保持した以外は、実施例１と同様にして実施例４の電極材料を得た。
<Example 4>
In the step (1) of the method for producing the electrode material of Example 1, the charged amounts of the Pt precursor and the Ti oxide precursor were set to 20.3 wt% of Pt and 1.7 wt% of Ti as the supported amount after forming the electrode material. % (Pt: Ti (molar ratio) = 3:1), and in step (2), held at 240 ° C. for 3 hours under N 2 atmosphere, and then held for 30 minutes in 3% humidified N 2 An electrode material of Example 4 was obtained in the same manner as in Example 1, except that
また、実施例の電極材料と比較するための標準触媒として、田中貴金属工業株式会社製Ｐｔ担持カーボン（Ｐｔ/Ｃ、品番：ＴＥＣ１０Ｅ５０Ｅ、Ｐｔ担持率４６ｗｔ％）を使用した。 As a standard catalyst for comparison with the electrode materials of Examples, Pt-supported carbon (Pt/C, product number: TEC10E50E, Pt-supported rate: 46 wt%) manufactured by Tanaka Kikinzoku Kogyo Co., Ltd. was used.
実施例１～４及び比較例１として使用したＰｔ／Ｃ標準触媒の電極材料を表１にまとめて示す。なお、表１におけるＰｔ担持率は、ＩＣＰ測定での実測値（括弧は仕込み値）である。 Table 1 summarizes the electrode materials of the Pt/C standard catalysts used in Examples 1 to 4 and Comparative Example 1. It should be noted that the Pt loading in Table 1 is an actual value measured by ICP measurement (values in parentheses are charged values).
２．物性評価
２－１．Ｘ線回折（ＸＲＤ）による解析
調製した各電極材料の結晶構造をＸＲＤによって評価した。図２に実施例１の電極材料、図３に実施例３の電極材料、図４に実施例４の電極材料のＸＲＤパターンを示す。なお、２θが約２７°のピークはＧＣＢに起因するピークである。
いずれの電極材料においても、Ｐtピークが確認され、Ｐtが結晶として存在していることが認められた。一方、いずれの電極材料においても、ＴｉＯ２のピークが確認できなかったことから、Ｔｉは非常に微小なＴｉＯ２結晶あるいは非晶質のＴｉ酸化物（ＴｉＯｘ）として存在していると判断できる。
また、ＰｔＴｉやＰｔ３Ｔｉなどの合金の明確なピークは確認されないことから、ＰｔとＴｉの合金はほとんど形成されていないと判断できる。
2. Physical property evaluation 2-1. Analysis by X-Ray Diffraction (XRD) The crystal structure of each prepared electrode material was evaluated by XRD. XRD patterns of the electrode material of Example 1 are shown in FIG. 2, the electrode material of Example 3 is shown in FIG. 3, and the electrode material of Example 4 is shown in FIG. The peak at 2θ of about 27° is due to GCB.
A Pt peak was confirmed in all electrode materials, and it was confirmed that Pt was present as crystals. On the other hand, since the peak of TiO 2 could not be confirmed in any of the electrode materials, it can be judged that Ti exists as very fine TiO 2 crystals or amorphous Ti oxide (TiOx).
In addition, since no clear peaks for alloys such as PtTi and Pt 3 Ti are observed, it can be determined that almost no alloy of Pt and Ti is formed.
また、Scherrer法により求めた実施例１，３，４の電極材料のＰｔ微粒子の結晶子径をそれぞれ表２に示す。いずれの条件で調製した電極材料についても、２ｎｍ程度の結晶子径を有するＰｔ微粒子が形成されていることが明らかになった。 Table 2 shows the crystallite diameters of the Pt fine particles of the electrode materials of Examples 1, 3 and 4 obtained by the Scherrer method. It was found that Pt fine particles having a crystallite diameter of about 2 nm were formed in the electrode materials prepared under any conditions.
２－２．微細構造評価
実施例３の電極材料の微細構造評価を行った結果を図５及び図６に示す。
実施例３の電極材料のＦＥ－ＳＥＭ像（図５（ａ））及びＴＥＭ像（図５（ｂ））から、ＧＣＢに粒径１～２ｎｍの粒子が高分散に担持されていることが確認された。
また、図６に実施例３の電極材料のＳＴＥＭ像及びＥＤＳ分析を示す。図６のＥＤＳ分析からわかるように、粒径１～２ｎｍのＰｔ粒子の間に入り込むようにＴｉ酸化物が分布し、ＰｔとＴｉ酸化物とのコンポジット構造を形成していることがわかる。Ｐｔ粒子の間にＴｉ酸化物が入り込むことでＰｔの粒成長が抑えられ、粒径１～２ｎｍ程度の微小なＰｔ粒子が保持できていると判断した。
上述の通り、ＸＲＤ測定の結果からはＴｉＯ２のピークは検出されず、ＴｉＯ２結晶の存在を確認できなかったが、ＥＤＳ分析結果からはＴｉの存在は確認できたことから、Ｔｉ酸化物は存在していると判断した。
2-2. Microstructural Evaluation The results of microstructural evaluation of the electrode material of Example 3 are shown in FIGS.
From the FE-SEM image (FIG. 5(a)) and the TEM image (FIG. 5(b)) of the electrode material of Example 3, it was confirmed that particles with a particle size of 1 to 2 nm were supported on the GCB in a highly dispersed manner. was done.
Moreover, the STEM image and EDS analysis of the electrode material of Example 3 are shown in FIG. As can be seen from the EDS analysis of FIG. 6, Ti oxide is distributed so as to enter between Pt particles with a particle size of 1 to 2 nm, forming a composite structure of Pt and Ti oxide. It was determined that the grain growth of Pt was suppressed by Ti oxide entering between Pt particles, and fine Pt particles having a particle size of about 1 to 2 nm could be retained.
As described above, no TiO 2 peak was detected from the results of the XRD measurement, and the presence of TiO 2 crystals could not be confirmed, but the presence of Ti could be confirmed from the EDS analysis results. determined to exist.
実施例４の電極材料の微細構造評価を行った結果を図７に示す。
図３（ｂ）で示したＰｔ：Ｔｉ=１：１（ｍｏｌ比）で調製した実施例３の電極材料のＴＥＭ像と比較すると、Ｐｔ：Ｔｉ=３：１（ｍｏｌ比）で調製した実施例４の電極材料の方が、より微小な粒子が高分散に担持されていることが認められる一方で、一部で粒子が凝集している箇所も確認された。
FIG. 7 shows the result of microstructural evaluation of the electrode material of Example 4. As shown in FIG.
Compared with the TEM image of the electrode material of Example 3 prepared with Pt:Ti=1:1 (mol ratio) shown in FIG. In the electrode material of Example 4, it was found that finer particles were supported in a highly dispersed manner, but it was also confirmed that the particles were partially aggregated.
３．電気化学的評価（ハーフセル）
３－１．電気化学的表面積（ＥＣＳＡ）の評価
実施例１～４及び比較例１の電極材料について、サイクリックボルタンメトリー（ＣＶ）を行い、ＣＶから求めた水素吸着量から電気化学的表面積（ＥＣＳＡ）を算出した。なお、ＥＣＳＡは、電極材料に含まれるＰｔの有効表面積に相当する。
3. Electrochemical evaluation (half-cell)
3-1. Evaluation of electrochemical surface area (ECSA) Cyclic voltammetry (CV) was performed on the electrode materials of Examples 1 to 4 and Comparative Example 1, and the electrochemical surface area (ECSA) was calculated from the amount of hydrogen adsorption obtained from the CV. . ECSA corresponds to the effective surface area of Pt contained in the electrode material.
ＣＶの測定条件は以下の通りである。なお、１原子のＰｔに付き １原子のＨが吸着すると仮定すると２１０μＣ/ｃｍ2の電気量となる。
測定：三電極式セル（作用極：電極材料／ＧＣ、対極：Ｐｔ、参照極：Ａｇ／ＡｇＣｌ）
電解液：０．１Ｍ ＨＣｌＯ4（ｐＨ：約１）
測定電位範囲：０．０５～１．２Ｖ（可逆水素電極基準）
走査速度 ：５０ ｍＶ／ｓ
水素吸着量：０．０５～０．４Ｖの水素吸着を示すピーク面積から算出
電気化学的表面積（ＥＣＳＡ）：下記式より算出
ＥＣＳＡ＝（水素吸着量）[μＣ] / ２１０[μＣ/ｃｍ2]
The CV measurement conditions are as follows. Assuming that one atom of H is adsorbed per one atom of Pt, the amount of electricity is 210 μC/cm 2 .
Measurement: Three-electrode cell (working electrode: electrode material/GC, counter electrode: Pt, reference electrode: Ag/AgCl)
Electrolyte: 0.1M HClO4 (pH: about 1)
Measurement potential range: 0.05 to 1.2 V (based on reversible hydrogen electrode)
Scanning speed: 50 mV/s
Hydrogen adsorption amount: Calculated from the peak area indicating hydrogen adsorption at 0.05 to 0.4 V Electrochemical surface area (ECSA): Calculated from the following formula
ECSA = (hydrogen adsorption amount) [μC] / 210 [μC/cm 2 ]
実施例１～４及び比較例１の電極材料のＣＶにおいて水素の吸脱着に由来するピークが観察された（図示せず）。ＣＶから求めた実施例１～４及び比較例１の電極材料の電気化学的表面積（ＥＣＳＡ）の評価結果を図８に示す。
図８に示されるように、実施例１～４の電極材料は、比較例１の電極材料（Ｐｔ／Ｃ、標準触媒）と比較していずれもＥＣＳＡが大きいことが分かる。この結果は、上述の通り、実施例の電極材料におけるＰｔ粒子の粒径は１～２ｎｍ程度と非常に小さく、高分散担持され、Ｐｔ有効表面積が増大したことに起因していると判断した。
また、加湿処理を行っていない実施例１の電極材料よりも、加湿熱処理を行った実施例２（０．６％加湿）の方がＥＣＳＡが大きく、さらに水蒸気濃度を高めた実施例３（３％加湿）の方がＥＣＳＡがより大きいことが分かる。加湿雰囲気における熱処理によって、Ｔｉ前駆体（Ti(acac)2OiPr2）が十分に分解・酸化され、電極触媒複合体に含まれるＰｔ及びＴｉが、金属ＰｔとＴｉ酸化物（ＴｉＯｘ）に明確に相分離したことに起因していると判断した。
Ｐｔ：Ｔｉ=３：１（ｍｏｌ比）で調製した実施例４の電極材料の方が、Ｐｔ：Ｔｉ=１：１（ｍｏｌ比）で調製した実施例３の電極材料よりもＥＣＳＡが小さいが、上記微細構造評価の通り、実施例４の電極材料は、微小なＰｔ粒子が高分散に担持されているものの、一部で凝集している粒子が存在しているためと判断した。
In the CV of the electrode materials of Examples 1 to 4 and Comparative Example 1, peaks derived from hydrogen adsorption/desorption were observed (not shown). FIG. 8 shows the evaluation results of the electrochemical surface area (ECSA) of the electrode materials of Examples 1 to 4 and Comparative Example 1 obtained from CV.
As shown in FIG. 8, it can be seen that the electrode materials of Examples 1 to 4 all have larger ECSA than the electrode material of Comparative Example 1 (Pt/C, standard catalyst). As described above, it was determined that this result was due to the fact that the particle size of the Pt particles in the electrode material of the example was very small, about 1 to 2 nm, and that the Pt effective surface area was increased due to the highly dispersed and supported Pt particles.
In addition, the ECSA of Example 2 (0.6% humidification), which was subjected to humidification heat treatment, was larger than the electrode material of Example 1, which was not subjected to humidification treatment, and Example 3 (3 % humidification) has a higher ECSA. By heat treatment in a humidified atmosphere, the Ti precursor (Ti(acac) 2 OiPr 2 ) is sufficiently decomposed and oxidized, and the Pt and Ti contained in the electrode catalyst composite are clearly converted into metal Pt and Ti oxide (TiOx). It was determined that this was caused by phase separation.
Although the electrode material of Example 4 prepared with Pt:Ti=3:1 (molar ratio) has a smaller ECSA than the electrode material of Example 3 prepared with Pt:Ti=1:1 (molar ratio), , As in the microstructure evaluation, the electrode material of Example 4 has fine Pt particles supported in a highly dispersed manner, but it was determined that some particles aggregated partially.
３－２．ＯＲＲ活性の評価
実施例１～４及び比較例１の電極材料について、ＯＲＲ活性を評価した。
ＯＲＲ活性は、回転ディスク電極法（ＲＤＥ法）でリニアスイープボルタンメトリー（ＬＳＶ）を行い、得られる活性化支配電流（ik）を基に算出するMass activity（単位Ｐｔ質量当たりの活性）を指標とした。
Ｍａｓｓ ａｃｔｉｖｉｔｙ = ｉｋ / 電極上のＰｔ質量
活性化支配電流（ik）は、回転電極測定によって得られた電流－電位曲線について、任意の電位においてi-1とω-1/2でプロットして得られるKoutecky-Levichプロットを作成し、得られた直線を外挿することによって切片から求めた。
具体的な手順として、まず、Ｏ2を５０ｍＬ/分で３０分間バブリングした後、０．２ＶRHEから貴な方向に向けて１０ｍＶ/ｓで１．２０ＶRHEまで電位を走査し、測定を行なった。なお、測定中は常にＯ2を５０ｍＬ/分でパージした。なお、ＶRHEは可逆水素電極（ＲＨＥ）基準の電位である
3-2. Evaluation of ORR Activity The electrode materials of Examples 1 to 4 and Comparative Example 1 were evaluated for ORR activity.
The ORR activity is measured by linear sweep voltammetry (LSV) using the rotating disk electrode method (RDE method), and mass activity (activity per unit Pt mass) calculated based on the activation dominant current ( ik ) obtained as an index. did.
Mass activity = i k / Pt mass on electrode
The activation-dominant current (i k ) is obtained by plotting the current-potential curve obtained by the rotating electrode measurement with i -1 and ω -1/2 at an arbitrary potential to create a Koutecky-Levich plot, It was determined from the intercept by extrapolating the straight line obtained.
As a specific procedure, first, O 2 was bubbled at 50 mL/min for 30 minutes, and then the potential was scanned from 0.2 V RHE in the noble direction to 1.20 V RHE at 10 mV/s for measurement. Note that O 2 was always purged at 50 mL/min during the measurement. Note that V RHE is the potential based on the reversible hydrogen electrode (RHE)
図９に実施例１～３及び比較例１の電極材料のリニアスイープボルタモグラム(１６００ｒｐｍ)を示す。図９において、実施例１～３の対比から、熱処理における水蒸気濃度を高くするほど酸素還元電位がポジティブシフトしていることから、水蒸気共存下での熱処理により電極性能が向上していることが示された。
図１０に、実施例１～４及び比較例１の電極材料のMass activityの評価結果を示す。
図１０からわかるように、加湿なしの実施例１、または０．６％加湿の実施例２の電極材料は、比較例１の電極材料（Ｐ／Ｃ標準触媒）よりもMass activityが小さかった。一方、３％加湿の実施例３及び実施例４の電極材料は、比較例１の電極材料よりもMass activityが大きな値を示していた。３％加湿の実施例３の電極材料はではMass activityがはるかに大きくなっていることが確認された。これら結果から、Ｐｔ－ＴｉＯｘ/ＧＣＢからなる電極材料は、水蒸気共存下での熱処理により、Mass activityが増加すると判断した。なお、加湿なしの実施例１又は０．６％加湿の実施例２の電極材料はほとんどMass activityの値に差が見られなかったが、０．６％加湿窒素雰囲気での熱処理では不十分であったと判断した。
FIG. 9 shows linear sweep voltammograms (1600 rpm) of the electrode materials of Examples 1 to 3 and Comparative Example 1. FIG. In FIG. 9, from the comparison of Examples 1 to 3, the higher the water vapor concentration in the heat treatment, the more positive the oxygen reduction potential shifts, indicating that the heat treatment in the presence of water vapor improves the electrode performance. was done.
FIG. 10 shows the mass activity evaluation results of the electrode materials of Examples 1 to 4 and Comparative Example 1. As shown in FIG.
As can be seen from FIG. 10, the electrode material of Example 1 without humidification or Example 2 with 0.6% humidification had a lower mass activity than the electrode material of Comparative Example 1 (P/C standard catalyst). On the other hand, the electrode materials of Examples 3 and 4 with 3% humidity showed a larger mass activity value than the electrode material of Comparative Example 1. It was confirmed that the electrode material of Example 3 with 3% humidity had a much higher mass activity. From these results, it was determined that the electrode material composed of Pt--TiOx/GCB had increased mass activity by heat treatment in the coexistence of water vapor. The electrode materials of Example 1 without humidification and Example 2 with 0.6% humidification showed almost no difference in mass activity value, but heat treatment in a 0.6% humidified nitrogen atmosphere was insufficient. I judged that there was.
３－３．負荷変動サイクル試験
ＯＲＲ活性が最大となった実施例３の電極材料について、負荷変動サイクル耐久性試験を行った。負荷変動サイクル試験は、燃料電池実用化推進協議会（ＦＣＣＪ）が推奨する方法（固体高分子形燃料電池の目標・研究開発課題と評価方法の提案、平成２３年１月発行）にて、負荷変動を模擬した電位サイクルを負荷することによって行った。図１１に示す負荷変動サイクルは，触媒自体の溶解・再析出などを伴う劣化を促進させるサイクルであり、０．６～１．０ ＶRHEの短形波を用いて１サイクル当たり３秒ずつの６秒負荷することで実験を行い、４０万サイクル後のＥＣＳＡを測定した。
3-3. Load Variation Cycle Test The load variation cycle durability test was performed on the electrode material of Example 3 that maximized the ORR activity. The load fluctuation cycle test was conducted using the method recommended by the Fuel Cell Commercialization Promotion Council (FCCJ) This was done by applying potential cycles that simulated fluctuations. The load fluctuation cycle shown in FIG. 11 is a cycle that promotes deterioration accompanied by dissolution and reprecipitation of the catalyst itself, and uses a rectangular wave of 0.6 to 1.0 V RHE for 3 seconds per cycle. An experiment was conducted by loading for 6 seconds, and ECSA was measured after 400,000 cycles.
図１２に負荷変動サイクル試験(４０万サイクル)における実施例３及び比較例１の電極材料のＥＣＳＡ変化を示す。
図１２からわかるように、ＥＣＳＡが初期値の５０％を切ったのは、比較例１の電極材料（Ｐｔ/Ｃ）で４万サイクルであり、実施例３の電極材料で６万サイクルであった。また、４０万サイクル後のＥＣＳＡ保持率は、比較例１の電極材料で１４．９％、実施例３の電極材料で２３．７ ％であった。また、負荷変動サイクル試験のＯＲＲ活性を評価したところ（図示せず）、負荷変動サイクル印加による酸素還元電位のネガティブシフトが小さいことが確認されたことから、実施例３の電極材料はＥＣＳＡとＯＲＲ活性の両面で、標準触媒である比較例１の電極材料（Ｐｔ/Ｃ）より高い負荷変動サイクル耐久性を有していることが確認された。
FIG. 12 shows ECSA changes of the electrode materials of Example 3 and Comparative Example 1 in the load fluctuation cycle test (400,000 cycles).
As can be seen from FIG. 12, ECSA fell below 50% of the initial value at 40,000 cycles for the electrode material (Pt/C) of Comparative Example 1 and at 60,000 cycles for the electrode material of Example 3. rice field. The ECSA retention rate after 400,000 cycles was 14.9% for the electrode material of Comparative Example 1 and 23.7% for the electrode material of Example 3. In addition, when the ORR activity of the load variation cycle test was evaluated (not shown), it was confirmed that the negative shift of the oxygen reduction potential due to the application of the load variation cycle was small. In terms of both activity, it was confirmed that the catalyst had a load fluctuation cycle durability higher than that of the electrode material (Pt/C) of Comparative Example 1, which was the standard catalyst.
本発明の電極材料によれば、優れた電極触媒活性、電子伝導性、ガス拡散性、及び優れた耐久性を有する電極を供することができる。当該電極は、長期運転が必要である固体高分子形燃料電池用の電極に好適である。 According to the electrode material of the present invention, an electrode having excellent electrocatalytic activity, electronic conductivity, gas diffusibility, and excellent durability can be provided. The electrode is suitable as an electrode for polymer electrolyte fuel cells that require long-term operation.
Claims (14)
前記電極触媒複合体は、電極触媒粒子と、電子伝導性酸化物とを含み、
前記電子伝導性酸化物は、前記電極触媒粒子の間を埋めるように存在することを特徴とする電極材料。 including a carbon-based conductive auxiliary material and an electrode catalyst composite supported on the carbon-based conductive auxiliary material,
The electrocatalyst composite comprises electrocatalyst particles and an electronically conductive oxide,
The electrode material, wherein the electronically conductive oxide is present so as to fill spaces between the electrode catalyst particles.
工程（１）：疎水性有機溶媒に、炭素系導電補助材を分散させた分散液に、電極触媒粒子前駆体のアセチルアセトナート化合物と、電子伝導性酸化物前駆体のアセチルアセトナート化合物とを溶解させ、撹拌及び溶媒の留去を行うことにより、電極触媒粒子前駆体と電子伝導性酸化物前駆体とが担持された炭素系導電補助材を得る工程
工程（２）：工程（１）で得られた電極触媒粒子前駆体と電子伝導性酸化物前駆体とが担持された炭素系導電補助材を、不活性ガス雰囲気で熱処理することによって、電極触媒複合体を形成する工程 A manufacturing method of the electrode material according to any one of claims 1 to 7, comprising the following steps (1) and (2).
Step (1): An acetylacetonate compound as an electrode catalyst particle precursor and an acetylacetonate compound as an electron conductive oxide precursor are added to a dispersion liquid in which a carbon-based conductive auxiliary material is dispersed in a hydrophobic organic solvent. Process step (2) for obtaining a carbon-based conductive auxiliary material supporting an electrode catalyst particle precursor and an electron conductive oxide precursor by dissolving, stirring, and distilling off the solvent: in step (1) A step of forming an electrode catalyst composite by heat-treating the obtained carbon-based conductive auxiliary material on which the electrode catalyst particle precursor and the electron conductive oxide precursor are supported in an inert gas atmosphere.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005085607A (en) | 2003-09-09 | 2005-03-31 | Mitsubishi Rayon Co Ltd | Anode catalyst for fuel cell, and its manufacturing method |
| JP2005270864A (en) | 2004-03-25 | 2005-10-06 | Nissan Motor Co Ltd | Fuel cell electrode catalyst and manufacturing method therefor |
| JP2014093255A (en) | 2012-11-06 | 2014-05-19 | Toyota Motor Corp | Manufacturing method of composite catalyst for fuel cell and composite catalyst for fuel cell |
| JP2014209484A (en) | 2014-05-22 | 2014-11-06 | 国立大学法人宮崎大学 | Method for manufacturing fuel battery catalyst |
| JP2020161273A (en) | 2019-03-26 | 2020-10-01 | 国立大学法人九州大学 | Manufacturing method of electrode material |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005085607A (en) | 2003-09-09 | 2005-03-31 | Mitsubishi Rayon Co Ltd | Anode catalyst for fuel cell, and its manufacturing method |
| JP2005270864A (en) | 2004-03-25 | 2005-10-06 | Nissan Motor Co Ltd | Fuel cell electrode catalyst and manufacturing method therefor |
| JP2014093255A (en) | 2012-11-06 | 2014-05-19 | Toyota Motor Corp | Manufacturing method of composite catalyst for fuel cell and composite catalyst for fuel cell |
| JP2014209484A (en) | 2014-05-22 | 2014-11-06 | 国立大学法人宮崎大学 | Method for manufacturing fuel battery catalyst |
| JP2020161273A (en) | 2019-03-26 | 2020-10-01 | 国立大学法人九州大学 | Manufacturing method of electrode material |
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