JP2005087993A - Catalyst composition for fuel cell - Google Patents
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- 239000003054 catalyst Substances 0.000 title claims abstract description 67
- 239000000446 fuel Substances 0.000 title claims abstract description 49
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- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
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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
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Abstract
Description
本発明は燃料電池用触媒組成物に関し、さらに詳しくは、かさ密度が高く、かつ比表面積が大きい炭素担体を用いることで高い発電性能を示す燃料電池用触媒組成物に関する。 The present invention relates to a fuel cell catalyst composition, and more particularly to a fuel cell catalyst composition exhibiting high power generation performance by using a carbon support having a high bulk density and a large specific surface area.
カーボンブラック、活性炭、カーボンエアロゲル、高配向性グラファイト、カーボンナノチューブに代表される炭素材料は粒子内の電気抵抗が低く、比表面積も大きいため、良好な電極材料として用いられている。しかし、最近の電池用触媒用途においては、炭素担体のバルク体としての導電性の高さや、比表面積のさらなる向上が求められており、これらの点から、最近はカーボンナノチューブが注目されている。 Carbon materials typified by carbon black, activated carbon, carbon aerogel, highly oriented graphite, and carbon nanotubes are used as good electrode materials because of their low electrical resistance in the particles and large specific surface area. However, in recent battery catalyst applications, there is a demand for further improvement in the high conductivity and specific surface area of the carbon support as a bulk body. From these points, carbon nanotubes have recently attracted attention.
カーボンナノチューブは、グラファイトの１枚面を巻いて筒状にした形状を有しており、一層に巻いたものを単層カーボンナノチューブ、多層に巻いたものを多層カーボンナノチューブという。これらのカーボンナノチューブは、高い機械的強度、高い導電性を有することから、電極材料以外に、樹脂や有機半導体との複合材料、吸着材料、医薬用ナノカプセル、ＭＲＩ造影剤、フィールドエミッションの電子源として大きく期待されている。 The carbon nanotube has a shape in which one surface of graphite is wound into a cylindrical shape. A single-walled carbon nanotube is referred to as a single-walled carbon nanotube, and a multi-walled carbon nanotube is referred to as a multilayered one. Since these carbon nanotubes have high mechanical strength and high conductivity, in addition to electrode materials, composite materials with resins and organic semiconductors, adsorbing materials, pharmaceutical nanocapsules, MRI contrast agents, field emission electron sources It is highly expected.
電極材料の応用例として燃料電池用電極材料がある。燃料電池は、排気ガス中に、未燃炭化水素やＮＯｘ、ＳＯｘを含まず、また、エネルギー効率が高いことから、環境への負荷が小さく、将来の発電システムとして期待されている。燃料電池は、燃料極、イオン伝導膜、空気極からなり、イオン伝導膜の種類により、固体高分子形、リン酸塩形、溶融炭酸塩形、固体電解質形の４種類に分けられる。特に、プロトン伝導性を有する固体高分子形に関して幅広く研究が進められている。固体高分子形プロトン伝導膜としては、デュポン社のナフィオンがある。また、燃料極に供給する燃料として、水素を供給するタイプ、炭化水素を改質するタイプ、およびメタノールを直接供給するタイプがある。特にメタノールを直接供給するタイプでは、電極に高いメタノール分解能つまり高い発電効率が求められる。電池用電極に炭素材料を用いる場合、炭素材料上にプロトン乖離能を有する触媒金属を担持する必要がある。このような触媒金属として、一般に白金を含む粒子が用いられる。また、高い発電効率を満たすためには、金属触媒の分散性だけでなく、炭素材料の界面抵抗の低下も要求される。 As an application example of the electrode material, there is a fuel cell electrode material. The fuel cell does not contain unburned hydrocarbons, NOx, and SOx in the exhaust gas, and has high energy efficiency. Therefore, the load on the environment is small and is expected as a future power generation system. A fuel cell is composed of a fuel electrode, an ion conductive membrane, and an air electrode, and is classified into four types according to the type of the ion conductive membrane: a solid polymer type, a phosphate type, a molten carbonate type, and a solid electrolyte type. In particular, extensive research has been conducted on solid polymer forms having proton conductivity. As a solid polymer type proton conductive membrane, there is Nafion manufactured by DuPont. Further, as a fuel supplied to the fuel electrode, there are a type for supplying hydrogen, a type for reforming hydrocarbons, and a type for directly supplying methanol. In particular, in the type in which methanol is directly supplied, high methanol resolution, that is, high power generation efficiency is required for the electrode. When a carbon material is used for the battery electrode, it is necessary to support a catalytic metal having proton detachment ability on the carbon material. As such a catalyst metal, particles containing platinum are generally used. Moreover, in order to satisfy high power generation efficiency, not only the dispersibility of the metal catalyst but also the reduction of the interface resistance of the carbon material is required.
例えば、カレン・リーン・ブラウンらは、炭素材料にかさ密度が０．１ｇ／ｃｃ以上と高い炭素繊維を用い、燃料電池用触媒組成物としている（特許文献１）。しかし、一般的な炭素繊維であることから、炭素材料の表面積が小さく、触媒金属の微粒子化、および高分散化には不向きであった。 For example, Karen Lean Brown et al. Uses a carbon fiber having a high bulk density of 0.1 g / cc or more as a carbon material as a fuel cell catalyst composition (Patent Document 1). However, since it is a general carbon fiber, the surface area of the carbon material is small, and it is unsuitable for making catalyst metal fine particles and highly dispersing.
また、Ｃ．Ａ．Ｂｅｓｓｅｌらは、炭素材料としてグラファイトナノファイバーを適用している（非特許文献１）。しかし、担持金属（白金）の粒子径分布が２ｎｍから１０ｎｍ以上までと均一でなく、かつ大きい粒子も含まれていた。 In addition, C.I. A. Bessel et al. Apply graphite nanofibers as a carbon material (Non-patent Document 1). However, the particle size distribution of the supported metal (platinum) was not uniform from 2 nm to 10 nm or more, and large particles were included.
また、Ｅ．Ｓ．Ｓｔｅｉｇｅｒｗａｌｔらは、炭素材料としてグラファイトナノファイバーだけでなく、単層カーボンナノチューブ、多層カーボンナノチューブを適用し、金属触媒に白金／ルテニウム混合触媒を用いている（非特許文献２）。その中で、最も高い発電効率を示したherringbone GCNFでは０．３Ｖ、０．５５Ａ／ｃｍ２を得ているが、未だ実用化レベルになく、単層、多層カーボンナノチューブでは、さらに低い性能であった。
水素イオン乖離能が高く、かつ、一酸化炭素の被毒が少ない高性能な燃料電池用触媒を提供する。 Provided is a high-performance fuel cell catalyst having high hydrogen ion dissociation ability and low carbon monoxide poisoning.
前記課題を達成するため、本発明は主として次のような構成をとる。 In order to achieve the above object, the present invention mainly has the following configuration.
すなわち、かさ密度が０．１ｇ／ｃｃ以上であり、かつ、窒素吸着法で測定した比表面積が３００ｍ２／ｇ以上である炭素材料に貴金属を担持した炭素材料を用いることを特徴とする。 That is, a carbon material having a noble metal supported on a carbon material having a bulk density of 0.1 g / cc or more and a specific surface area measured by a nitrogen adsorption method of 300 m 2 / g or more is used.
本発明により得られた燃料電池用触媒組成物を用いることにより、水素イオン乖離能が高く、かつ、一酸化炭素の被毒が少ない高性能な触媒を提供できる。 By using the fuel cell catalyst composition obtained by the present invention, a high-performance catalyst having high hydrogen ion dissociation ability and low carbon monoxide poisoning can be provided.
特に、炭素材料に２層カーボンナノチューブを用い、貴金属に白金とルテニウムを用いることで、ダイレクトメタノール形燃料電池に適した触媒組成物を提供することができる。 In particular, a catalyst composition suitable for a direct methanol fuel cell can be provided by using double-walled carbon nanotubes as a carbon material and platinum and ruthenium as noble metals.
以下、本発明の最良の実施形態の例を説明する。 Examples of the best embodiment of the present invention will be described below.
本発明は、かさ密度が０．１ｇ／ｃｃ以上であり、かつ、窒素吸着法で測定した比表面積が３００ｍ２／ｇ以上である炭素材料に貴金属を担持したことを特徴とする燃料電池用触媒組成物に関するものである。 The present invention relates to a fuel cell catalyst characterized in that a noble metal is supported on a carbon material having a bulk density of 0.1 g / cc or more and a specific surface area measured by a nitrogen adsorption method of 300 m 2 / g or more. It relates to a composition.
ここでいう炭素材料とは、カーボンブラック、活性炭、カーボンエアロゲル、高配向性グラファイト、カーボンナノチューブに代表される粒子内の電気抵抗が低い材料のことを言う。 The carbon material here refers to a material having a low electrical resistance in the particles represented by carbon black, activated carbon, carbon aerogel, highly oriented graphite, and carbon nanotube.
それら炭素材料のかさ密度はJIS M 8811に従い，気乾試料に調整した後に、メスシリンダーに試料を投入し，タッピングした後の試料容積で試料重量を除して求めることができる。電池用途に用いる場合、かさ密度が低いと電極体積が大きくなり、電池の容積を低減できない。そこで、かさ密度は０．１ｇ／ｃｃ以上必要であり、より好ましくは０．１５ｇ／ｃｃ以上、さらに好ましくは０．２０ｇ／ｃｃ以上である。 The bulk density of these carbon materials can be obtained by adjusting the sample to an air-dried sample according to JIS M 8811, then putting the sample into a graduated cylinder and dividing the sample weight by the sample volume after tapping. When used for battery applications, if the bulk density is low, the electrode volume increases and the battery volume cannot be reduced. Therefore, the bulk density needs to be 0.1 g / cc or more, more preferably 0.15 g / cc or more, and still more preferably 0.20 g / cc or more.
一方、窒素吸着法による比表面積の測定は、前処理により試料の付着物を除去した後に液体窒素温度での窒素吸着量を測定することで求めることができる。前処理として、例えば、炭素材料を３００℃以上、３時間以上、１．０×１０−３Ｐａ程度に真空引きする方法が好んで用いられる。前処理した試料へ供給する窒素の吸着量からＢＥＴ法により試料の比表面積を求めることができる。比表面積が高いほど金属触媒を高分散担持できるため好ましい。そこで、比表面積は３００ｍ２／ｇ以上必要であり、より好ましくは４００ｍ２／ｇ以上、さらに好ましくは５００ｍ２／ｇ以上である。 On the other hand, the measurement of the specific surface area by the nitrogen adsorption method can be obtained by measuring the nitrogen adsorption amount at the liquid nitrogen temperature after removing the deposits of the sample by the pretreatment. As the pretreatment, for example, a method in which a carbon material is evacuated to about 1.0 × 10 −3 Pa at 300 ° C. or more for 3 hours or more is preferably used. The specific surface area of the sample can be determined by the BET method from the adsorption amount of nitrogen supplied to the pretreated sample. A higher specific surface area is preferable because the metal catalyst can be highly dispersed and supported. Therefore, the specific surface area is required to be 300 m 2 / g or more, more preferably 400 m 2 / g or more, and still more preferably 500 m 2 / g or more.
また、本発明で炭素担体に担持する貴金属とは、金、銀、白金、ロジウム、イリジウム、パラジウム、ルテニウムおよびオスミウムから選ばれる少なくとも一つであることが好ましい。 In the present invention, the noble metal supported on the carbon support is preferably at least one selected from gold, silver, platinum, rhodium, iridium, palladium, ruthenium and osmium.
また、本発明は炭素材料がカーボンナノチューブを含むことが好ましい。ここで、カーボンナノチューブとは、グラファイトの１枚面を巻いて筒状にした形状を有しており、一層に巻いたものを単層カーボンナノチューブ、２層に巻いたものを２層カーボンナノチューブ、多層に巻いたものを多層カーボンナノチューブという。これらのカーボンナノチューブは、高い機械的強度、高い導電性を有することが特徴である。カーボンナノチューブのかさ密度が０．１ｇ／ｃｃ以上であり、かつ、窒素吸着法で測定した比表面積が３００ｍ２／ｇ以上であれば、層数によらず本発明の目的に好んで用いられることができる。一般的に単層カーボンナノチューブは、かさ密度が極めて低く、かつファン・デア・ワールス力によりバンドル（束）を形成しやすく、実質的な比表面積が小さい。また、多層カーボンナノチューブは、その層数によるが、比表面積が小さいものが多い。以上の理由から、かさ密度が高く、かつ、比表面積が大きい２層カーボンナノチューブが、本用途では最も好んで用いられる。これらカーボンナノチューブの製造方法は特に限定されないが、工業化の容易さから、アーク放電法、気相成長法（ＣＶＤ法）、触媒担持気相成長法（ＣＣＶＤ法）が好んで用いられる。 In the present invention, the carbon material preferably contains carbon nanotubes. Here, the carbon nanotube has a shape in which one surface of graphite is wound into a cylindrical shape, a single-walled carbon nanotube is obtained by winding one layer, a double-walled carbon nanotube is obtained by winding two layers, A multi-walled carbon nanotube is a multi-walled carbon nanotube. These carbon nanotubes are characterized by high mechanical strength and high electrical conductivity. If the bulk density of the carbon nanotube is 0.1 g / cc or more and the specific surface area measured by the nitrogen adsorption method is 300 m 2 / g or more, it is preferably used for the purpose of the present invention regardless of the number of layers. Can do. In general, single-walled carbon nanotubes have a very low bulk density, easily form bundles by van der Waals force, and have a small specific surface area. Further, many multi-walled carbon nanotubes have a small specific surface area depending on the number of layers. For these reasons, double-walled carbon nanotubes having a high bulk density and a large specific surface area are most preferably used in this application. Although the manufacturing method of these carbon nanotubes is not particularly limited, the arc discharge method, the vapor phase growth method (CVD method), and the catalyst-supported vapor phase growth method (CCVD method) are preferably used because of the ease of industrialization.
カーボンナノチューブの含有量は、炭素材料が上記かさ密度と比表面積を満たす限り特に限定されないが、含有量が多い方が上記特性を満たしやすく、好んで用いられる。その含有量は１０％以上が好ましく、より好ましくは３０％以上、さらに好ましくは５０％以上である。カーボンナノチューブの含有量の求め方は、特に限定されるものではないが、例えば、試料をエタノールなど揮発性の高い溶媒に添加し、炭素材料を溶媒中に分散させた後、その溶媒数滴をマイクログリッド上に滴下し、溶媒を揮発させた後に、透過型電子顕微鏡で観察する手法が好んで用いられる。カーボンナノチューブを観察するためには、倍率を１０万倍以上、好ましくは２０万倍以上に上げる手法が用いられる。観察した視野内にある全ての物質の面積を算出し、その中に占めるカーボンナノチューブの面積の割合で求めることができる。 The content of the carbon nanotube is not particularly limited as long as the carbon material satisfies the above-described bulk density and specific surface area, but a higher content tends to satisfy the above characteristics and is preferably used. The content is preferably 10% or more, more preferably 30% or more, and still more preferably 50% or more. The method for obtaining the content of the carbon nanotube is not particularly limited. For example, after adding a sample to a highly volatile solvent such as ethanol and dispersing the carbon material in the solvent, several drops of the solvent are added. The method of observing with a transmission electron microscope after dripping on a microgrid and volatilizing a solvent is used preferably. In order to observe the carbon nanotube, a method of increasing the magnification to 100,000 times or more, preferably 200,000 times or more is used. The area of all the substances in the observed visual field can be calculated, and the area ratio of the carbon nanotubes in the area can be obtained.
カーボンナノチューブの種類は特に限定されないが、２層カーボンナノチューブが好んで用いられる。その理由は、２層カーボンナノチューブはバンドルを形成しにくく、かつ層数が少ないため、実質的に比表面積が大きいことがあげられる。また、単層カーボンナノチューブや多層カーボンナノチューブに比べ、かさ密度が高いため、燃料電池用触媒用途に特に適していることがあげられる。以上の理由から、２層カーボンナノチューブの含有量も高い方が好ましい。全炭素材料中に占める２層カーボンナノチューブの含有量は、５％以上が好ましく、より好ましくは１５％以上、さらに好ましくは２５％以上、最も好ましくは５０％以上である。 Although the kind of carbon nanotube is not particularly limited, a double-walled carbon nanotube is preferably used. The reason is that the double-walled carbon nanotube is difficult to form a bundle and has a small number of layers, and therefore has a substantially large specific surface area. Moreover, since the bulk density is higher than single-walled carbon nanotubes and multi-walled carbon nanotubes, it is particularly suitable for fuel cell catalyst applications. For the above reasons, it is preferable that the content of double-walled carbon nanotubes is also high. The content of double-walled carbon nanotubes in the total carbon material is preferably 5% or more, more preferably 15% or more, still more preferably 25% or more, and most preferably 50% or more.
また、２層カーボンナノチューブの内径は、細い方が比表面積が大きくなり好ましい。特に、共鳴ラマン散乱測定により、１５０〜３５０ｃｍ−１の領域にピークが観察される２層カーボンナノチューブでは内径が２ｎｍより小さく、比表面積が大きくなり、貴金属を高分散担持しやすいので好ましく用いられる。 Further, it is preferable that the inner diameter of the double-walled carbon nanotube is narrower because the specific surface area becomes larger. In particular, double-walled carbon nanotubes whose peaks are observed in the region of 150 to 350 cm −1 by resonance Raman scattering measurement are preferably used because the inner diameter is smaller than 2 nm, the specific surface area is increased, and noble metals are easily supported in a highly dispersed manner.
カーボンナノチューブの内径、および層数は透過型電子顕微鏡で観察することができる。ここでいう透過型電子顕微鏡による２層カーボンナノチューブの観察手法は、特に限定されるものではないが、例えば、試料をエタノールなど揮発性の高い溶媒に添加し、ナノチューブを溶媒中に分散させた後、その溶媒数滴をマイクログリッド上に滴下し、溶媒を揮発させた後に、電子顕微鏡で観察する手法が好んで用いられる。２層カーボンナノチューブを観察するためには、倍率を１０万倍以上、好ましくは２０万倍以上に上げる手法が用いられる。壁が２枚のグラフェンシートから構成されるカーボンナノチューブが２層カーボンナノチューブであり、その内側のグラフェンシート間の距離がカーボンナノチューブの内径である。２層カーボンナノチューブの比表面積を３００ｍ２／ｇ以上とするためには、内径は１０ｎｍ以下が好ましい。また、内径が１ｎｍの２層カーボンナノチューブはバンドルを形成しにくいため、より好ましく用いられる。 The inner diameter and the number of layers of the carbon nanotube can be observed with a transmission electron microscope. The observation method of the double-walled carbon nanotube by the transmission electron microscope here is not particularly limited. For example, after adding the sample to a highly volatile solvent such as ethanol and dispersing the nanotube in the solvent A method of observing with an electron microscope after dropping several drops of the solvent on the microgrid and volatilizing the solvent is preferably used. In order to observe the double-walled carbon nanotube, a method of increasing the magnification to 100,000 times or more, preferably 200,000 times or more is used. The carbon nanotube in which the wall is composed of two graphene sheets is a double-walled carbon nanotube, and the distance between the graphene sheets on the inner side is the inner diameter of the carbon nanotube. In order to set the specific surface area of the double-walled carbon nanotube to 300 m 2 / g or more, the inner diameter is preferably 10 nm or less. In addition, a double-walled carbon nanotube having an inner diameter of 1 nm is more preferably used because it is difficult to form a bundle.
炭素材料の導電性が高い方が燃料電池の発電効率が高まり好ましい。炭素材料の導電性は、共鳴ラマン散乱測定により見積もることができる。共鳴ラマン散乱では、1００〜３５０ ｃｍ−１付近のピークがＲＢＭ（Ｒａｄｉａｌ Ｂｒｅａｔｈｉｎｇ Ｍｏｄｅ）、１５６０〜１６００ｃｍ−１付近の構造がG-bandであり、その他に不純物のアモルファスやグラファイト構造の欠陥に起因するものとして、１３１０〜１３５０ｃｍ−１付近のD-bandと呼ばれるピークが観測される。炭素材料のG-bandは共鳴効果により強調されるため、試料の純度によって強度が大きく変化する。一方、１３３０ｃｍ−１付近のブロードなD-bandは不純物による寄与が大きく、これは共鳴効果により強い強調を受けないため、G-bandとD-bandの強度比を取ることにより、炭素材料中のグラファイト構造の純度を見積ることが可能となる。共鳴ラマン散乱測定により、１５６０〜１６００ｃｍ−１の範囲内で最大のピーク強度をＧ、１３１０〜１３５０ｃｍ−１の範囲内で最大のピーク強度をＤとしたときに、Ｇ／Ｄ比が１．５以上の炭素材料であれば燃料電池用途で十分な導電性が得られるため好ましい。一方、Ｇ／Ｄ比が３０以下では、炭素材料表面の平滑性が高すぎることがなく、貴金属粒子が担持しやすいので好ましく用いられる。 Higher conductivity of the carbon material is preferable because the power generation efficiency of the fuel cell is increased. The conductivity of the carbon material can be estimated by a resonance Raman scattering measurement. In resonance Raman scattering, a peak near 100 to 350 cm -1 is RBM (Radial Breathing Mode), a structure is G-band near 1560～1600Cm -1, Other due to defects in amorphous or graphite structure of the impurity As a thing, a peak called D-band around 1310 to 1350 cm −1 is observed. Since the G-band of the carbon material is emphasized by the resonance effect, the strength varies greatly depending on the purity of the sample. On the other hand, the broad D-band near 1330 cm −1 is greatly contributed by impurities, and this does not receive strong emphasis due to the resonance effect. Therefore, by taking the intensity ratio of G-band and D-band, It is possible to estimate the purity of the graphite structure. The resonance Raman scattering measurement, the maximum peak intensity in the range of 1560~1600cm -1 G, a maximum peak intensity in the range of 1310～1350Cm -1 when the D, G / D ratio 1.5 The above carbon materials are preferable because sufficient conductivity can be obtained for fuel cell applications. On the other hand, when the G / D ratio is 30 or less, the smoothness of the surface of the carbon material is not too high, and the noble metal particles are easily supported, so that it is preferable.
また、本発明は共鳴ラマン散乱測定法の測定により、１５００〜１６５０cm−１の範囲内のピークが分裂して観測されることを特徴とするカーボンナノチューブを含む燃料電池用触媒組成物に関するものである。共鳴ラマン散乱測定において、１５００〜１６５０cm−１の範囲内のピークは上述の通り、Ｇ−ｂａｎｄと呼ばれ、カーボンナノチューブのグラファイト化度の高さを示す指標となる。カーボンナノチューブのグラファイト化度が高い材料では、グラファイト構造に起因して、Ｇ−ｂａｎｄがさらに分裂して２本以上現れることがある。このようなカーボンナノチューブはグラファイト化度が高く、高い導電性を示すため好ましく用いられる。 The present invention also relates to a fuel cell catalyst composition comprising carbon nanotubes, characterized in that peaks in the range of 1500 to 1650 cm −1 are observed by splitting as measured by a resonance Raman scattering measurement method. . In the resonance Raman scattering measurement, the peak in the range of 1500 to 1650 cm −1 is called G-band as described above and serves as an index indicating the degree of graphitization of the carbon nanotube. In a material having a high degree of graphitization of carbon nanotubes, two or more G-bands may appear due to further splitting due to the graphite structure. Such carbon nanotubes are preferably used because they have a high degree of graphitization and high conductivity.
また本発明は、透過型電子顕微鏡でチューブの少なくとも片端の最外層が開放端となっているカーボンナノチューブを含む燃料電池用触媒組成物に関するものであり、より好ましくは片端の層全てが開放端となっているカーボンナノチューブを含む燃料電池用触媒組成物に関するものであり、さらに好ましくは両端の層全てが開放端となっているカーボンナノチューブを含む燃料電池用触媒組成物に関するものである。カーボンナノチューブの末端が開放端になることで、チューブ末端部分への貴金属粒子の担持が容易となり、かつ、チューブ内側にも貴金属粒子を担持でき、実質的に比表面積が向上することとなり好ましい。これら開放端は、製造直後から形成されているものが多いが、カーボンナノチューブの精製処理によって、カーボンナノチューブ合成用触媒からカーボンナノチューブが切り離されるときに開放端になる場合もある。 The present invention also relates to a catalyst composition for a fuel cell comprising a carbon nanotube in which at least one outermost layer of the tube is an open end in a transmission electron microscope, and more preferably, all the one end layers are open ends. The present invention relates to a fuel cell catalyst composition containing carbon nanotubes, and more preferably to a fuel cell catalyst composition containing carbon nanotubes in which both end layers are open ends. It is preferable that the end of the carbon nanotube is an open end, so that the noble metal particles can be easily supported on the end portion of the tube, and the noble metal particles can be supported on the inside of the tube, and the specific surface area is substantially improved. Many of these open ends are formed immediately after production, but may become open ends when the carbon nanotubes are separated from the catalyst for carbon nanotube synthesis by the purification process of the carbon nanotubes.
また本発明は、炭素材料に金、銀、白金、ロジウム、イリジウム、パラジウム、ルテニウムおよびオスミウムから選ばれる少なくとも一つを含む金属を担持している燃料電池用触媒組成物に関するものである。特に白金は、水素乖離能が高く好んで用いられる。また、燃料電池電極触媒では、供給ガス中の一酸化炭素により白金が被毒され、触媒活性が低下することが問題となる。この問題を解決するために、一酸化炭素分解活性が高い触媒を助触媒的に加える方法がしばしば好んで用いられ、金属種としてはルテニウムが適している。また、白金とルテニウムのモル組成比は４：１から１：４の間であることが好ましく、特に好ましくは２：１から１：２の間であることが好ましい。この範囲であれば、白金の比率が高すぎて、一酸化炭素の除去が不十分となり、触媒活性が低下する問題や、また、ルテニウムの比率が高すぎて、ルテニウムには水素乖離能がないため触媒活性自体が低下する問題が起こることがない。 The present invention also relates to a fuel cell catalyst composition in which a carbon material is loaded with a metal containing at least one selected from gold, silver, platinum, rhodium, iridium, palladium, ruthenium and osmium. In particular, platinum is preferred because of its high hydrogen dissociation ability. Further, in the fuel cell electrode catalyst, there is a problem that platinum is poisoned by carbon monoxide in the supply gas and the catalytic activity is lowered. In order to solve this problem, a method of adding a catalyst having a high carbon monoxide decomposition activity as a cocatalyst is often used, and ruthenium is suitable as the metal species. The molar composition ratio of platinum and ruthenium is preferably between 4: 1 and 1: 4, particularly preferably between 2: 1 and 1: 2. If it is in this range, the platinum ratio is too high, carbon monoxide removal becomes insufficient, the catalytic activity is reduced, and the ruthenium ratio is too high, and ruthenium has no hydrogen dissociation ability. Therefore, there is no problem that the catalytic activity itself decreases.
本発明における触媒の調製法は、特に限定されるものではない。貴金属の担持方法として、貴金属をそのままスパッタリングなどの方法で担持してもよいし、貴金属塩を含浸法、平衡吸着法、イオン交換法などの公知の方法で担持し、その後還元処理を行って貴金属粒子を得る方法でも良い。 The method for preparing the catalyst in the present invention is not particularly limited. As a method for supporting the noble metal, the noble metal may be supported by a method such as sputtering as it is, or a noble metal salt is supported by a known method such as an impregnation method, an equilibrium adsorption method, an ion exchange method, and then subjected to a reduction treatment to perform noble metal treatment. A method of obtaining particles may also be used.
例えば含浸法を用いた場合、通常、貴金属の塩もしくは錯体を溶媒に溶解させ、担体に担持する。溶媒としては貴金属の塩もしくは錯体を溶解できるものであれば特に限定はないが、水またはメタノール、エタノールなどが好ましく、特にエタノールが好ましい。貴金属の塩もしくは錯体としては、各種の塩化物、硝酸塩、炭酸塩、錯体を単独または混合して用いてもかまわない。特にこれらの中でも化合物の形態として、硝酸塩や炭酸塩、錯体、特にアンミン錯体が好ましい。 For example, when an impregnation method is used, a noble metal salt or complex is usually dissolved in a solvent and supported on a carrier. The solvent is not particularly limited as long as it can dissolve a noble metal salt or complex, but water, methanol, ethanol and the like are preferable, and ethanol is particularly preferable. As the noble metal salt or complex, various chlorides, nitrates, carbonates and complexes may be used alone or in combination. Among these, nitrates, carbonates and complexes, particularly ammine complexes are preferred as the form of the compound.
また、貴金属化合物を用いる場合、いくつかの化合物の混合物を用いても良いし、複塩でもよい。 Moreover, when using a noble metal compound, the mixture of several compounds may be used and double salt may be sufficient.
貴金属を担持するのに、貴金属の塩もしくは錯体を担持し、その後還元する方法をとる場合、還元方法についても特には限定されない。例えば過酸化水素、ヒドラジンなどの還元剤を用いてもよいし、水素、窒素などの無機ガスによる還元を行ってもよい。特には、還元したときに生じる貴金属粒子の粒径を小さく制御できるため、窒素／水素混合ガス中で加熱分解して還元する方法が好ましい。さらに、水素／窒素のモル組成比としては、分解温度を制御し易いという点で、２０％以下であることが好ましく、特に好ましくは１０％以下であることが好ましい。 When a method of supporting a noble metal by supporting a noble metal salt or complex and then reducing the noble metal, the reduction method is not particularly limited. For example, a reducing agent such as hydrogen peroxide or hydrazine may be used, or reduction with an inorganic gas such as hydrogen or nitrogen may be performed. In particular, since the particle diameter of the noble metal particles generated upon reduction can be controlled to be small, a method of reducing by thermal decomposition in a nitrogen / hydrogen mixed gas is preferable. Furthermore, the molar composition ratio of hydrogen / nitrogen is preferably 20% or less, particularly preferably 10% or less, in terms of easy control of the decomposition temperature.
また、加熱分解還元するときの温度は、貴金属粒子の凝集を防ぐために、４００℃以下で行うことが好ましく、さらに好ましくは３００℃以下、特に好ましくは２５０℃以下で加熱分解還元することが好ましい。 Further, the temperature during the thermal decomposition and reduction is preferably 400 ° C. or lower, more preferably 300 ° C. or lower, particularly preferably 250 ° C. or lower, in order to prevent aggregation of the noble metal particles.
また本発明は、炭素担体に対する白金の担持量が２５ｗｔ％以上である燃料電池用触媒組成物に関するものである。本発明にある比表面積が大きい炭素担体を用いることで白金担持量が多くても白金粒子を微粒子状で高分散担持することができる。白金の担持量は多いほど好ましく、３０ｗｔ％以上がより好んで用いられる。また、さらに好ましくは３５ｗｔ％以上である。 The present invention also relates to a fuel cell catalyst composition in which the amount of platinum supported on a carbon support is 25 wt% or more. By using the carbon support having a large specific surface area according to the present invention, platinum particles can be finely dispersed and supported even if the amount of platinum supported is large. The larger the amount of platinum supported, the more preferable, and 30 wt% or more is more preferable. More preferably, it is 35 wt% or more.
また本発明は、Ｘ線回折結果からＢｅｇａｒｄ則で求めた白金とルテニウムの固溶量が３０ａｔｍ％以上である燃料電池用触媒組成物に関するものである。ここで、白金とルテニウムの固溶量はＸ線回折結果から得られる格子定数を以下に示すＢｅｇａｒｄの式に代入して求めることができる（サーフェス・サイエンス(Surf.Sci.) 293,(1993)p67-）。 The present invention also relates to a fuel cell catalyst composition in which the solid solution amount of platinum and ruthenium determined by the Begard rule from the X-ray diffraction results is 30 atm% or more. Here, the solid solution amount of platinum and ruthenium can be obtained by substituting the lattice constant obtained from the X-ray diffraction result into the following Begard equation (Surf. Sci.) 293, (1993). p67-).
ｙ＝−８００６ｘ＋３１４３
（ｘは格子定数（単位：ｎｍ）、ｙは固溶量（単位：％））
ここで、固溶量が０％であるとき、白金とルテニウムは合金化しておらず、個々に結晶を形成していることを意味する。この固溶量が３０％以下では、ルテニウムによる白金上の一酸化炭素の除去が不十分で触媒活性を維持できない。固溶量はより好ましくは３５％以上であり、さらに好ましくは４０％以上である。
y = −8006x + 3143
(X is a lattice constant (unit: nm), y is a solid solution amount (unit:%))
Here, when the solid solution amount is 0%, it means that platinum and ruthenium are not alloyed and form crystals individually. If the solid solution amount is 30% or less, the removal of carbon monoxide on platinum by ruthenium is insufficient, and the catalytic activity cannot be maintained. The amount of solid solution is more preferably 35% or more, and still more preferably 40% or more.
また、本発明は、炭素材料に担持した貴金属粒子の平均粒子径が１ｎｍ以上かつ５ｎｍ以下であることが好ましい。ここで貴金属粒子の平均粒子径は、以下のように定義する。透過型電子顕微鏡で観察した貴金属粒子の粒子サイズについて、２００度数をとり円換算粒子径分布を求めたときの平均値を平均粒子径と定義する。貴金属粒子を観察するためには、透過型電子顕微鏡の倍率を１０万倍以上、好ましくは２０万倍以上に上げる手法が用いられる。観察視野内の金属粒子を無作為に２００個抽出し、それぞれの粒子を球状と見なしたときの直径を円換算粒子径とし、２００個の円換算粒子径を平均化する。その値が１ｎｍ以下では、粒径が小さすぎるために触媒としての安定性が低く好ましくない。平均粒子径が１ｎｍ以上、かつ５ｎｍ以下である場合には、高い触媒活性を示し、かつ安定性も高い。平均粒子径が５ｎｍ以上では、金属あたりの触媒活性が低下し、貴金属の担持量を増加させる必要があり、好ましくない。 In the present invention, the noble metal particles supported on the carbon material preferably have an average particle diameter of 1 nm or more and 5 nm or less. Here, the average particle diameter of the noble metal particles is defined as follows. With respect to the particle size of the noble metal particles observed with a transmission electron microscope, the average value when the circular conversion particle size distribution is obtained by taking 200 degrees is defined as the average particle size. In order to observe the precious metal particles, a technique of increasing the magnification of the transmission electron microscope to 100,000 times or more, preferably 200,000 times or more is used. 200 metal particles in an observation field are randomly extracted, and the diameter when each particle is regarded as a spherical shape is defined as a circle-converted particle diameter, and the 200 circle-converted particle diameters are averaged. If the value is 1 nm or less, the particle size is too small, so the stability as a catalyst is low, which is not preferable. When the average particle size is 1 nm or more and 5 nm or less, high catalytic activity is exhibited and stability is high. When the average particle size is 5 nm or more, the catalytic activity per metal is lowered, and it is necessary to increase the amount of noble metal supported, which is not preferable.
また本発明は、ダイレクトメタノール形燃料電池用触媒として用いられる燃料電池用触媒組成物に関するものである。上述の触媒を用いることで、メタノールを効率よく分解し、水素イオンを発生でき、かつ、一酸化炭素の被毒が少ない高性能な触媒を提供できる。 The present invention also relates to a fuel cell catalyst composition used as a direct methanol fuel cell catalyst. By using the above-described catalyst, it is possible to provide a high-performance catalyst that can efficiently decompose methanol, generate hydrogen ions, and has little carbon monoxide poisoning.
以下、実施例により本発明を具体的に説明するが、下記の実施例は例示のために示すものであって、いかなる意味においても、本発明を限定的に解釈するものとして使用してはならない。 EXAMPLES Hereinafter, the present invention will be specifically described by way of examples. However, the following examples are given for illustrative purposes and should not be used in any way as a limited interpretation of the present invention. .
（実施例１）
Ａ．炭素材料の物性測定
ＣＣＶＤ法で合成した東レ製２層カーボンナノチューブ（Ｒタイプ）をJIS M 8811に従い，気乾試料に調整した後に、メスシリンダーに試料を投入し，タッピングした後の試料容積で試料重量を除して求めかさ密度を求めた結果、０．２５ｇ／ｃｃであった。
(Example 1)
A. Measurement of physical properties of carbon materials Toray-made double-walled carbon nanotubes (R type) synthesized by CCVD method are adjusted to air-dried samples in accordance with JIS M 8811, then the sample is put into a graduated cylinder and the sample volume is tapped. The bulk density obtained by dividing the weight was 0.25 g / cc.
また、上記２層カーボンナノチューブを３００℃、３時間、１．０×１０−３Ｐａに真空引きした後に窒素を吸着させ、その吸着量からＢＥＴ法により比表面積を求めた結果、６１０ｍ２／ｇであった。 Moreover, after vacuuming the above-mentioned double-walled carbon nanotube to 1.0 × 10 −3 Pa at 300 ° C. for 3 hours, nitrogen was adsorbed, and the specific surface area was determined by the BET method from the adsorbed amount, resulting in 610 m 2 / g Met.
Ｂ．触媒調製及び電極化法
白金前駆体としてPt(NH3)2(NO2)2、ルテニウム前駆体としてRuNO(NO3)xを用いた。これら前駆体をそれぞれ金属濃度が4 mMとなるようにエタノールに溶解した後、白金とルテニウムのモル比を1:1として混合し、前駆体溶液を調製した。この前駆体溶液を２層カーボンナノチューブに所定の金属担持量となるように混合した。２層カーボンナノチューブを加えた前駆体溶液を30分間超音波処理して十分に分散させた後、ホットスターラーで攪拌しながら60℃で乾燥させた。乾燥後に得られた粉末をめのう乳鉢で粉砕した後、水素/窒素（1:9）混合気体を流速250 mL/minで流通させながら、200℃で2時間熱分解を行いPtRu/C触媒を調製した。本触媒の透過型電子顕微鏡写真を図１に示す。
B. Catalyst Preparation and Electrodeization Method Pt (NH3) 2 (NO2) 2 was used as the platinum precursor and RuNO (NO3) x was used as the ruthenium precursor. These precursors were each dissolved in ethanol so that the metal concentration was 4 mM, and then mixed with a molar ratio of platinum and ruthenium of 1: 1 to prepare a precursor solution. This precursor solution was mixed with the double-walled carbon nanotube so as to have a predetermined metal loading. The precursor solution to which the double-walled carbon nanotubes were added was sonicated for 30 minutes and sufficiently dispersed, and then dried at 60 ° C. while stirring with a hot stirrer. After the powder obtained after drying is pulverized in an agate mortar, a PtRu / C catalyst is prepared by pyrolysis at 200 ° C for 2 hours while flowing a hydrogen / nitrogen (1: 9) gas mixture at a flow rate of 250 mL / min. did. A transmission electron micrograph of this catalyst is shown in FIG.
PtRu/C粉末試料の電気化学的な特性評価は、以下の手順に従って試験電極を作成した。PtRu/C粉末試料を微量の蒸留水で湿らせたあと、2 g/Lとなるようにメタノールを加え、30分間超音波にて均一に分散させた。得られた分散液を、＃3000のエメリー紙にて平滑研磨したグラッシーカーボン（GC）電極上に20 μL滴下した。60℃で乾燥させた後、メタノールで5倍量に希釈したNafion（商標） 溶液を10 μL滴下し電極触媒を固定化後、再び60℃で乾燥した。PtRu/C/GC電極を集電体である真鍮製の電極ホルダーに固定し、試料面（見かけ表面積0.196 cm２）のみが露出するようにGC電極および電極ホルダーをテフロン（登録商標）テープで絶縁し、試験電極とした。 For electrochemical characterization of PtRu / C powder samples, test electrodes were prepared according to the following procedure. After the PtRu / C powder sample was moistened with a small amount of distilled water, methanol was added to a concentration of 2 g / L, and the mixture was uniformly dispersed with ultrasonic waves for 30 minutes. 20 μL of the obtained dispersion was dropped onto a glassy carbon (GC) electrode smooth-polished with # 3000 emery paper. After drying at 60 ° C., 10 μL of Nafion ™ solution diluted 5 times with methanol was added dropwise to immobilize the electrode catalyst, and then dried again at 60 ° C. Fix the PtRu / C / GC electrode to the brass electrode holder that is the current collector, and insulate the GC electrode and electrode holder with Teflon (registered trademark) tape so that only the sample surface (apparent surface area 0.196 cm 2 ) is exposed. And used as a test electrode.
Ｃ．電気化学測定法
電解セルにはビーカー型三極式を使用し、対極には白金メッシュ、参照極にはAg/AgCl電極を使用した。電解セルを用いた全ての電気化学測定は、ポテンショスタット（北斗電工社製電気化学測定システムHZ-3000）によって行った。測定は25℃の恒温槽中に設置した電解セルに、脱酸素処理した窒素を吹き込んで電解液中の溶存酸素を除去しながら行った。また電極電位は、可逆水素電極（RHE）電位基準で表示した。試験電極表面の不純物を取り除くために、電位走査速度100 mV/sで100サイクルの電気化学的前処理を行った。このときの電位走査範囲は、0.05〜0.8 V(vs. RHE)とした。PtRu/C触媒における電位範囲の上限は、金属Ruの不可逆酸化を防ぐためである。サイクリックボルタンメトリーはこの電気化学的処理の後、上記の電位走査範囲で、10 mV s-1の走査速度で行った。
C. Electrochemical measurement method A beaker type triode was used for the electrolysis cell, a platinum mesh was used for the counter electrode, and an Ag / AgCl electrode was used for the reference electrode. All electrochemical measurements using the electrolytic cell were performed with a potentiostat (Hokuto Denko Electrochemical Measurement System HZ-3000). The measurement was performed while blowing deoxygenated nitrogen into an electrolytic cell installed in a constant temperature bath at 25 ° C. while removing dissolved oxygen in the electrolytic solution. The electrode potential was displayed on the basis of a reversible hydrogen electrode (RHE) potential. In order to remove impurities on the test electrode surface, 100 cycles of electrochemical pretreatment were performed at a potential scanning rate of 100 mV / s. The potential scanning range at this time was 0.05 to 0.8 V (vs. RHE). The upper limit of the potential range in the PtRu / C catalyst is to prevent irreversible oxidation of metal Ru. Cyclic voltammetry was performed after this electrochemical treatment at a scan rate of 10 mV s-1 in the above potential scan range.
電極触媒に吸着したCOの酸化特性および電極触媒上に担持された金属比表面積を算出するため、飽和COadの電気化学的酸化特性を評価した。まず、サイクリックボルタンメトリーにてアノード走査中の水素脱離波が終了した電位で保持した。このときの電位は、PtRu/Cの場合0.3 V(vs. RHE)とした。続いてCOガスを電解セル内へ40分間吹き込み、電極触媒表面にCOを吸着させ、40分間窒素を吹き込むことで溶液中に残存するCOを除去した。最後にサイクリックボルタンメトリーを行い、1サイクル目と2サイクル目を記録した。 In order to calculate the oxidation characteristics of CO adsorbed on the electrode catalyst and the specific surface area of the metal supported on the electrode catalyst, the electrochemical oxidation characteristics of saturated COad were evaluated. First, it was held at a potential at which the hydrogen desorption wave during the anode scanning was completed by cyclic voltammetry. The potential at this time was 0.3 V (vs. RHE) in the case of PtRu / C. Subsequently, CO gas was blown into the electrolytic cell for 40 minutes, CO was adsorbed on the surface of the electrode catalyst, and nitrogen was blown for 40 minutes to remove CO remaining in the solution. Finally, cyclic voltammetry was performed and the first and second cycles were recorded.
メタノールを含む硫酸水溶液を電解液とした半電池による電極触媒のメタノール酸化活性を評価した。電解液に1 Mとなるようにメタノールを加えた0.5 M H2SO4を用いた。測定は電位ステップ定電位分極法により行った。このときのステップ電位は、75 mV(vs. RHE)から500 mV(vs. RHE)と変化させた。 The methanol oxidation activity of the electrocatalyst by a half-cell using a sulfuric acid aqueous solution containing methanol as an electrolyte was evaluated. 0.5 MH 2 SO 4 in which methanol was added to the electrolyte so as to be 1 M was used. The measurement was performed by the potential step constant potential polarization method. The step potential at this time was changed from 75 mV (vs. RHE) to 500 mV (vs. RHE).
Pt30wt%Ru15wt%となるように調製した触媒において、金属比表面積あたりの酸化電流値として、14μＡ／ｃｍ２の高活性を示した。 In Pt30wt% Ru15wt% become so prepared catalyst, as an oxidation current value per metal specific surface area, showed high activity of 14μA / cm 2.
（比較例１）
実施例１の２層カーボンナノチューブの代わりに、市販のカーボンブラック（東海カーボン製、ＳＡＦシリーズ）を用いた。JIS M 8811に従い，気乾試料に調整した後に、メスシリンダーに試料を投入し，タッピングした後の試料容積で試料重量を除して求めかさ密度を求めた結果、０．３１ｇ／ｃｃであった。
(Comparative Example 1)
Instead of the double-walled carbon nanotubes of Example 1, commercially available carbon black (SAF series, manufactured by Tokai Carbon Co., Ltd.) was used. According to JIS M 8811, after adjusting to an air-dried sample, the sample was put into a graduated cylinder, the sample volume was divided by the sample volume after tapping, and the bulk density was determined. The result was 0.31 g / cc. .
また、上記カーボンブラックを３００℃、３時間、１．０×１０−３Ｐａに真空引きした後に窒素を吸着させ、その吸着量からＢＥＴ法により比表面積を求めた結果、１４０ｍ２／ｇであった。 Further, the carbon black 300 ° C., 3 hours, 1.0 × 10 -3 Pa nitrogen is adsorbed after evacuation, the results of obtaining the specific surface area by the BET method from the adsorbed amount, 140 m 2 / g met It was.
Pt30wt%Ru15wt%となるように調製した触媒において、金属比表面積あたりの酸化電流値として、８μＡ／ｃｍ２の活性を示した。 In the catalyst prepared so that it might become Pt30wt% Ru15wt%, the activity of 8 microampere / cm < 2 > was shown as an oxidation current value per metal specific surface area.
本発明で得られた燃料電池用触媒組成物は、水素イオン乖離能が高く、かつ、一酸化炭素の被毒が少ない高性能な燃料電池用触媒を提供する。他にも、水素化反応触媒、石油ガス改質触媒、脱水素化反応触媒などにも応用することができるが、その応用範囲は、これらに限られるものではない。 The fuel cell catalyst composition obtained by the present invention provides a high-performance fuel cell catalyst having high hydrogen ion dissociation ability and low carbon monoxide poisoning. In addition, the present invention can be applied to hydrogenation reaction catalysts, petroleum gas reforming catalysts, dehydrogenation reaction catalysts, and the like, but the application range is not limited to these.
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| KR100717792B1 (en) | 2005-11-21 | 2007-05-11 | 삼성에스디아이 주식회사 | Cathode catalyst for fuel cell, membrane-electrode assembly for fuel cell comprising same and fuel cell system comprising same |
| WO2009060582A1 (en) | 2007-11-09 | 2009-05-14 | Kyusyu University, National University Corporation | Method for producing electrode material for fuel cell, electrode material for fuel cell, and fuel cell using the electrode material for fuel cell |
| JP2017128497A (en) * | 2016-01-19 | 2017-07-27 | デクセリアルズ株式会社 | Porous carbon material and method for manufacturing same, and filter, sheet, and catalyst carrier |
| WO2017126421A1 (en) * | 2016-01-19 | 2017-07-27 | デクセリアルズ株式会社 | Porous carbon material, method for manufacturing same, filter, sheet, and catalyst carrier |
| JP2019104676A (en) * | 2017-12-13 | 2019-06-27 | 株式会社キャスティングイン | Method for producing silver-supporting charcoal powder and method for producing silver-supporting charcoal powder-containing toothpaste |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR100717792B1 (en) | 2005-11-21 | 2007-05-11 | 삼성에스디아이 주식회사 | Cathode catalyst for fuel cell, membrane-electrode assembly for fuel cell comprising same and fuel cell system comprising same |
| WO2009060582A1 (en) | 2007-11-09 | 2009-05-14 | Kyusyu University, National University Corporation | Method for producing electrode material for fuel cell, electrode material for fuel cell, and fuel cell using the electrode material for fuel cell |
| US8398884B2 (en) | 2007-11-09 | 2013-03-19 | Kyushu University, National University Corporation | Method for producing electrode material for fuel cell, electrode material for fuel cell, and fuel cell using the electrode material for fuel cell |
| JP2017128497A (en) * | 2016-01-19 | 2017-07-27 | デクセリアルズ株式会社 | Porous carbon material and method for manufacturing same, and filter, sheet, and catalyst carrier |
| WO2017126421A1 (en) * | 2016-01-19 | 2017-07-27 | デクセリアルズ株式会社 | Porous carbon material, method for manufacturing same, filter, sheet, and catalyst carrier |
| JP2019104676A (en) * | 2017-12-13 | 2019-06-27 | 株式会社キャスティングイン | Method for producing silver-supporting charcoal powder and method for producing silver-supporting charcoal powder-containing toothpaste |
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| Zhao et al. | Multi-wall carbon nanotube supported Pt–Sn nanoparticles as an anode catalyst for the direct ethanol fuel cell | |
| Sebastián et al. | Optimizing the synthesis of carbon nanofiber based electrocatalysts for fuel cells | |
| Huang et al. | Novel graphite-carbon encased tungsten carbide nanocomposites by solid-state reaction and their ORR electrocatalytic performance in alkaline medium | |
| Zhu et al. | Superior catalytic activity of Pt/carbon nanohorns nanocomposites toward methanol and formic acid oxidation reactions | |
| Li et al. | Metal-organic interface engineering for coupling palladium nanocrystals over functionalized graphene as an advanced electrocatalyst of methanol and ethanol oxidation | |
| Jiang et al. | Worm-like PtP nanocrystals supported on NiCo2Px/C composites for enhanced methanol electrooxidation performance | |
| Sebastián et al. | The influence of carbon nanofiber support properties on the oxygen reduction behavior in proton conducting electrolyte-based direct methanol fuel cells | |
| Chang et al. | Investigations of a platinum–ruthenium/carbon nanotube catalyst formed by a two-step spontaneous deposition method | |
| Chandran et al. | 1D-2D integrated hybrid carbon nanostructure supported bimetallic alloy catalyst for ethanol oxidation and oxygen reduction reactions | |
| Zheng et al. | Microstructure effect of carbon nanofiber on electrocatalytic oxygen reduction reaction | |
| Wu et al. | Pt nanodendrites anchored on bamboo-shaped carbon nanofiber arrays as highly efficient electrocatalyst for oxygen reduction reaction | |
| Suda et al. | Electrochemical properties of fuel cell catalysts loaded on carbon nanomaterials with different geometries |