JP5135599B2 - Method for producing carbon nanowall carrying metal - Google Patents

Method for producing carbon nanowall carrying metal Download PDF

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JP5135599B2
JP5135599B2 JP2005091791A JP2005091791A JP5135599B2 JP 5135599 B2 JP5135599 B2 JP 5135599B2 JP 2005091791 A JP2005091791 A JP 2005091791A JP 2005091791 A JP2005091791 A JP 2005091791A JP 5135599 B2 JP5135599 B2 JP 5135599B2
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carbon
carbon nanowall
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JP2006273613A (en
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勝 堀
美根男 平松
浩之 加納
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Nagoya University NUC
NU Eco Engineering Co Ltd
Tokai National Higher Education and Research System NUC
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NU Eco Engineering Co Ltd
Tokai National Higher Education and Research System NUC
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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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
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Description

本発明はカーボンナノウォールに金属を担持させる方法に関する。   The present invention relates to a method for supporting a metal on a carbon nanowall.

本発明者は、カーボンナノウォールを開発し、非特許文献１の通り報告している。なおカーボンナノウォールとは、二次元的な広がりをもつカーボンナノ構造体である。カーボンナノウォールの典型例は、基材の表面からほぼ一定の方向に立ち上がった壁状の構造を有するカーボンナノ構造体である。なお、フラーレン（Ｃ60等）は０次元のカーボンナノ構造体とみることができ、カーボンナノチューブは一次元のカーボンナノ構造体とみることができる。
Appl. Phys. Lett., Vol. 23, p. 4708 (2004) The inventor has developed carbon nanowalls and reported them as described in Non-Patent Document 1. The carbon nanowall is a carbon nanostructure having a two-dimensional spread. A typical example of the carbon nanowall is a carbon nanostructure having a wall-like structure that rises in a substantially constant direction from the surface of the substrate. Note that fullerenes (C 60 and the like) can be regarded as zero-dimensional carbon nanostructures, and carbon nanotubes can be regarded as one-dimensional carbon nanostructures.
Appl. Phys. Lett., Vol. 23, p. 4708 (2004)

カーボンナノウォールの用途として、例えば、グラファイト電極の代替が挙げられる。ここにおいて、いわゆるプロトン交換膜（ＰＥＭ）を用いた燃料電池の反応電極として用いることも考えられる。   As an application of the carbon nanowall, for example, an alternative to a graphite electrode is given. Here, use as a reaction electrode of a fuel cell using a so-called proton exchange membrane (PEM) is also conceivable.

しかしカーボンナノウォール自体のみでは、燃料電池の反応電極として用いることは困難である。そこで、反応を促進する触媒、特に白金等の金属触媒をコーティング等することが必要である。しかし、例えば高さが１μｍ程度で、０．１μｍ程度の間隙を以て基板等にほぼ垂直に形成された、カーボンナノウォールの表面（壁面）に金属触媒をコーティングすることは困難であった。即ち、そのようなカーボンナノウォールの表面（壁面）に金属触媒を付着させるため、金属触媒の分散液等を塗布したり、当該分散液にカーボンナノウォールを浸漬しても、カーボンナノウォールの表面（壁面）全体に十分に金属触媒を付着させることはできなかった。また、カーボンナノウォールは、高さ／幅の比が大きいので、カーボンナノウォールの底部まで、均一に、分散させて、金属を担持させることは、従来は不可能であった。   However, it is difficult to use the carbon nanowall itself as a reaction electrode of a fuel cell. Therefore, it is necessary to coat a catalyst that promotes the reaction, particularly a metal catalyst such as platinum. However, it has been difficult to coat a metal catalyst on the surface (wall surface) of the carbon nanowall, for example, having a height of about 1 μm and formed substantially perpendicular to the substrate or the like with a gap of about 0.1 μm. That is, in order to attach a metal catalyst to the surface (wall surface) of such a carbon nanowall, the surface of the carbon nanowall can be applied even if a metal catalyst dispersion liquid is applied or the carbon nanowall is immersed in the dispersion liquid. The metal catalyst could not be sufficiently adhered to the entire (wall surface). In addition, since the carbon nanowall has a large height / width ratio, it has been impossible in the past to uniformly disperse and carry a metal up to the bottom of the carbon nanowall.

そこで本発明者は、白金等の金属の化合物を、超臨界流体に溶解してカーボンナノウォールを処理することを着想し、本願発明を完成させた。   Therefore, the present inventor has conceived of treating a carbon nanowall by dissolving a compound of a metal such as platinum in a supercritical fluid, and completed the present invention.

請求項１に係る発明は、金属を担持させたカーボンナノウォールの製造方法であって、予め基板に形成したカーボンナノウォールに、金属の化合物を超臨界流体に溶解した状態で接触処理する処理工程を有し、その処理工程の際に、３００〜８００℃にカーボンナノウォールを加熱することを特徴とする金属を担持させたカーボンナノウォールの製造方法である。 The invention according to claim 1 is a method for producing a carbon nanowall carrying a metal, wherein the carbon nanowall previously formed on a substrate is subjected to a contact treatment in a state where a metal compound is dissolved in a supercritical fluid. have a, during the processing step, a method for producing a carbon nano-wall obtained by supporting a metal, which comprises heating the carbon nanowalls 300 to 800 ° C..

尚、この加熱はカーボンナノウォールを形成した基材（基板）の温度を言うものとする。 Incidentally, the heating shall refer to the temperature of the base material forming a carbon nano-wall (substrate).

また、請求項２に係る発明は、金属を担持させたカーボンナノウォールの製造方法であって、予め基板に形成したカーボンナノウォールに、金属の化合物を超臨界流体に溶解した状態で接触処理する処理工程を有し、金属は白金であることを特徴とする金属を担持させたカーボンナノウォールの製造方法である。
また、請求項３に係る発明は、金属を担持させたカーボンナノウォールの製造方法であって、予め基板に形成したカーボンナノウォールに、金属の化合物を超臨界流体に溶解した状態で接触処理する処理工程を有し、超臨界流体は二酸化炭素であることを特徴とする金属を担持させたカーボンナノウォールの製造方法である。
上記の発明において、金属の化合物は、有機金属錯体又は有機金属化合物であっても良い。また、金属はカーボンナノウォールの有する水素原子又はハロゲン原子に置換してカーボンナノウォールに担持されても良い。また、ハロゲン原子はフッ素であっても良い。 The invention according to claim 2 is a method for producing a carbon nanowall carrying a metal, wherein the carbon nanowall previously formed on the substrate is subjected to a contact treatment in a state where a metal compound is dissolved in a supercritical fluid. It is a manufacturing method of carbon nanowall carrying a metal, characterized in that it has a treatment step and the metal is platinum .
According to a third aspect of the present invention , there is provided a method for producing a carbon nanowall carrying a metal, wherein the carbon nanowall previously formed on the substrate is contact-treated in a state where the metal compound is dissolved in the supercritical fluid. A method for producing a carbon nanowall carrying a metal, characterized in that it has a treatment step and the supercritical fluid is carbon dioxide .
In the above invention, the metal compound may be an organometallic complex or an organometallic compound. Also, metals can be supported on the carbon nano-wall is replaced with a hydrogen atom or a halogen atom with the carbon nano-wall. In addition, Ha androgenic atom may be a fluorine.

後述するように、金属化合物を溶解した超臨界流体用いてカーボンナノウォールを処理すると、容易にカーボンナノウォールに金属を担持させることが見出された。超臨界流体は極性及び非極性の化合物を容易に溶解するので、金属を錯体又は化合物として超臨界流体に溶解させる。超臨界流体は、周知のように極めて狭い領域にも浸透するので、間隔が０．１μｍ程度のカーボンナノウォールの壁間にも浸透する。これによりカーボンナノウォール表面に金属錯体又は金属化合物が接触し、金属が遊離して単結晶化する。この金属の単結晶化の際には、カーボンナノウォールを加熱することが望ましい。この金属が遊離してカーボンナノウォールに析出する原因は、カーボンナノウォールの有する水素原子及び／又はフッ素原子やその他のハロゲン原子に置換したのち、加熱によって配位子が分解離脱する機構が考えられる。水素原子及び／又はフッ素原子は、カーボンナノウォールを形成する時の原料ガスに含まれている。しかし、カーボンナノウォールを形成した後に、水素原子及び／又はフッ素などのハロゲン原子のラジカルを照射することで、カーボンナノウォールの壁面に水素原子及び／又はフッ素などのハロゲン原子を配置させることもできる。これらの原子の密度より、担持させるべき金属原子の密度を制御することができる。また、カーボンナノウォールの底の部分にまで、これらの水素原子及び／又はフッ素などのハロゲン原子から成る置換促進原子を存在させることが可能となることから、カーボンナノウォールの底まで金属を担持させることが可能となる。   As described later, it has been found that when a carbon nanowall is treated with a supercritical fluid in which a metal compound is dissolved, the metal is easily supported on the carbon nanowall. Since supercritical fluids readily dissolve polar and nonpolar compounds, metals are dissolved in supercritical fluids as complexes or compounds. Since the supercritical fluid penetrates into a very narrow region as is well known, it penetrates between the walls of the carbon nanowall having a spacing of about 0.1 μm. As a result, the metal complex or metal compound comes into contact with the surface of the carbon nanowall, and the metal is liberated and single crystallized. During the single crystallization of the metal, it is desirable to heat the carbon nanowall. The reason why this metal is liberated and deposited on the carbon nanowall may be due to a mechanism in which the ligand is decomposed and separated by heating after substitution with a hydrogen atom and / or fluorine atom or other halogen atom of the carbon nanowall. . Hydrogen atoms and / or fluorine atoms are contained in the raw material gas when forming the carbon nanowall. However, after forming the carbon nanowall, a hydrogen atom and / or a halogen atom such as fluorine can be placed on the wall of the carbon nanowall by irradiating a radical of a halogen atom such as a hydrogen atom and / or fluorine. . The density of the metal atoms to be supported can be controlled by the density of these atoms. Further, since it becomes possible to have substitution promotion atoms composed of these hydrogen atoms and / or halogen atoms such as fluorine up to the bottom part of the carbon nanowall, the metal is supported to the bottom of the carbon nanowall. It becomes possible.

金属錯体又は金属化合物としては、所望の金属以外の構成成分がカーボンナノウォールに残留しないか、例えば加熱により容易に離脱する、又は炭化してカーボンナノウォール自体となるものが好ましい。ここにおいて、所望の金属以外に重元素を含まない、有機化合物を配位子とする、又は有機基のみを有する有機金属錯体又は有機金属化合物が好ましい。   As the metal complex or metal compound, those in which constituent components other than the desired metal do not remain in the carbon nanowall, or are easily separated by heating, for example, or carbonized to become the carbon nanowall itself are preferable. Here, an organometallic complex or an organometallic compound that does not contain a heavy element other than the desired metal, uses an organic compound as a ligand, or has only an organic group is preferable.

金属として白金を用いると、触媒作用の顕著な白金を担持するカーボンナノウォールを得ることができる。また、超臨界流体は、取扱いの容易な二酸化炭素を用いると簡便である。担持される金属の粒径は、カーボンナノウォールの壁間距離寄りも小さい１００ｎｍ以下が好ましく、１０ｎｍ以下がより好ましく、５ｎｍ以下が更に好ましい。   When platinum is used as the metal, carbon nanowalls carrying platinum having a remarkable catalytic action can be obtained. Further, the supercritical fluid is simple if carbon dioxide, which is easy to handle, is used. The particle size of the supported metal is preferably 100 nm or less, more preferably 10 nm or less, and even more preferably 5 nm or less, which is close to the distance between the carbon nanowalls.

まず、本発明を適用するための、カーボンナノウォールの製造方法の一例について述べる。尚、本発明は任意の方法で形成されたカーボンナノウォールに適用可能であって、以下の製造方法で形成されたカーボンナノウォールへの適用に限定されるものではない。   First, an example of a carbon nanowall manufacturing method for applying the present invention will be described. In addition, this invention is applicable to the carbon nanowall formed by arbitrary methods, Comprising: It is not limited to the application to the carbon nanowall formed by the following manufacturing methods.

図１はカーボンナノウォール（カーボンナノ構造体）製造装置の一例を示す構成図である。この装置１は、反応室１０と、その反応室１０内でプラズマを生じさせるプラズマ放電手段２０と、反応室１０に接続されたラジカル供給手段４０とを備える。   FIG. 1 is a configuration diagram showing an example of a carbon nanowall (carbon nanostructure) manufacturing apparatus. The apparatus 1 includes a reaction chamber 10, plasma discharge means 20 that generates plasma in the reaction chamber 10, and radical supply means 40 connected to the reaction chamber 10.

プラズマ放電手段２０は、略円板状の形状を有する第一電極２２および第二電極２４から成る平行平板型容量結合プラズマ（ＣＣＰ）発生機構として構成されている。
第一電極（カソード）２２には、マッチング回路（matching network）２６を介して電源２８が接続され、１３．５６ＭＨｚのＲＦ波を発生させる。
第二電極（アノード）２４は、反応室１０内で第一電極２２から離して配置される。両電極２２，２４の間隔は、例えば０．５〜１０ｃｍ、約５ｃｍとする。第二電極２４は接地されている。カーボンナノウォールの製造時には、この第二電極２４上に基板（基材）５を配置する。例えば、基材５のうちカーボンナノウォールを製造しようとする面が露出する（第一電極２２に対向する）ようにして、第二電極２４の表面上に基板５を配置する。第二電極２４には、基材温度調節手段としてのヒータ２５（例えばカーボンヒータ）が内蔵されている。 The plasma discharge means 20 is configured as a parallel plate capacitively coupled plasma (CCP) generating mechanism comprising a first electrode 22 and a second electrode 24 having a substantially disc shape.
A power source 28 is connected to the first electrode (cathode) 22 via a matching network 26 to generate a 13.56 MHz RF wave.
The second electrode (anode) 24 is disposed in the reaction chamber 10 away from the first electrode 22. The distance between the electrodes 22 and 24 is, for example, 0.5 to 10 cm and about 5 cm. The second electrode 24 is grounded. At the time of manufacturing the carbon nanowall, the substrate (base material) 5 is disposed on the second electrode 24. For example, the substrate 5 is disposed on the surface of the second electrode 24 so that the surface of the base material 5 on which the carbon nanowall is to be manufactured is exposed (opposite the first electrode 22). The second electrode 24 incorporates a heater 25 (for example, a carbon heater) as a substrate temperature adjusting means.

原料ガス３２としてＣ2Ｆ6を、ラジカル源ガス３６として水素ガス（Ｈ2）を、基板５として厚さ約０．５ｍｍのシリコン（Ｓｉ）基板を用いた。なお、このシリコン基板５は触媒（金属触媒等）を実質的に含まない。 C 2 F 6 was used as the source gas 32, hydrogen gas (H 2 ) was used as the radical source gas 36, and a silicon (Si) substrate having a thickness of about 0.5 mm was used as the substrate 5. The silicon substrate 5 does not substantially contain a catalyst (such as a metal catalyst).

第二電極２４上にシリコン基板５を、その（１００）面が第一電極２２側に向くようにしてセットした。原料導入口１２から反応室１０にＣ2Ｆ6（原料ガス）３２を供給するとともに、ラジカル源導入口４２から水素ガス（ラジカル源ガス）３６を供給した。また、反応室１０内のガスを排気口１６から排気した。そして、反応室１０内におけるＣ2Ｆ6の分圧が約２０ｍＴｏｒｒ、Ｈ2の分圧が約８０ｍＴｏｒｒ、全圧が約１００ｍＴｏｒｒとなるように、原料ガス３２およびラジカル源ガス３６の供給量（流量）ならびに排気条件を調節した。 The silicon substrate 5 was set on the second electrode 24 so that the (100) surface thereof faced the first electrode 22 side. C 2 F 6 (raw material gas) 32 was supplied from the raw material inlet 12 to the reaction chamber 10, and hydrogen gas (radical source gas) 36 was supplied from the radical source inlet 42. Further, the gas in the reaction chamber 10 was exhausted from the exhaust port 16. The supply amounts (flow rates) of the source gas 32 and the radical source gas 36 are set so that the partial pressure of C 2 F 6 in the reaction chamber 10 is about 20 mTorr, the partial pressure of H 2 is about 80 mTorr, and the total pressure is about 100 mTorr. ) And exhaust conditions were adjusted.

この条件で原料ガス３２を供給しながら、電源２８から第一電極２２に１３．５６ＭＨｚ、１００ＷのＲＦ電力を入力し、反応室１０内の原料ガス（Ｃ2Ｆ6）３２にＲＦ波を照射した。これにより原料ガス３２をプラズマ化し、第一電極２２と第二電極２４との間にプラズマ雰囲気３４を形成した。また、上記条件でラジカル源ガス３６を供給しながら、電源５８からコイル５２に１３．５６ＭＨｚ、５０ＷのＲＦ電力を入力し、ラジカル発生室４０内のラジカル源ガス（Ｈ2）３６にＲＦ波を照射した。これにより生成したＨラジカルを、ラジカル導入口１４から反応室１０内に導入した。このようにして、シリコン基板５の（１００）面に高さ約１μｍのカーボンナノ構造体を成長（堆積）させた。その間、必要に応じてヒータ２５および図示しない冷却装置を用いることにより、基板５の温度を約５００℃に保持した。 While supplying the raw material gas 32 under these conditions, RF power of 13.56 MHz and 100 W is input from the power source 28 to the first electrode 22, and the raw material gas (C 2 F 6 ) 32 in the reaction chamber 10 is irradiated with RF waves. did. As a result, the source gas 32 was turned into plasma, and a plasma atmosphere 34 was formed between the first electrode 22 and the second electrode 24. Further, while supplying the radical source gas 36 under the above conditions, 13.56 MHz and 50 W RF power is input from the power source 58 to the coil 52, and an RF wave is applied to the radical source gas (H 2 ) 36 in the radical generation chamber 40. Irradiated. H radicals thus generated were introduced into the reaction chamber 10 from the radical inlet 14. In this way, a carbon nanostructure having a height of about 1 μm was grown (deposited) on the (100) plane of the silicon substrate 5. Meanwhile, the temperature of the substrate 5 was maintained at about 500 ° C. by using a heater 25 and a cooling device (not shown) as needed.

上述のように、シリコン基板に形成されたカーボンナノウォールに、次のようにして白金を担持させた。図２に示す通り、反応槽１００内のマイクロヒータを有するサセプタ１１０にカーボンナノウォールを形成したシリコン基板（Ｓｕｂ）を載置し、反応槽１００内を１００℃の超臨界ＣＯ2で満たした。次にバルブ２１０により反応槽１００と遮断及び接続可能な撹拌槽２００にヘキサンに溶解したトリメチル（メチルシクロペンタジエニル）白金を入れ、超臨界ＣＯ2に溶解させた。次に撹拌槽２００内の圧力を反応槽１００内の圧力より大きくしてからバルブ２１０を開き、撹拌槽２００内部の白金化合物を溶解した超臨界ＣＯ2を反応槽１００に導入して、所定時間白金を析出させた。 As described above, platinum was supported on the carbon nanowall formed on the silicon substrate as follows. As shown in FIG. 2, a silicon substrate (Sub) on which carbon nanowalls were formed was placed on a susceptor 110 having a microheater in the reaction vessel 100, and the reaction vessel 100 was filled with supercritical CO 2 at 100 ° C. Next, trimethyl (methylcyclopentadienyl) platinum dissolved in hexane was placed in a stirring tank 200 that can be disconnected from and connected to the reaction tank 100 by a valve 210 and dissolved in supercritical CO 2 . Next, after the pressure in the stirring tank 200 is made higher than the pressure in the reaction tank 100, the valve 210 is opened, and supercritical CO 2 in which the platinum compound in the stirring tank 200 is dissolved is introduced into the reaction tank 100 for a predetermined time. Platinum was deposited.

ここにおいて、サセプタ１００のマイクロヒータで５００℃に加熱して３０分間及び１０分間で白金を析出させた場合と、マイクロヒータでの加熱を行わず、超臨界ＣＯ2の温度である１００℃でそのまま３０分間白金を析出させた場合について、ＸＰＳ（Ｘ線光電子分光法）によるスペクトルを図３に示す。白金担持処理前（未処理ＣＮＷ）は白金が全く検出されていないが、白金担持処理により白金が検出されることから、白金はカーボンナノウォールに担持されたことが理解できる。また、処理の際に、加熱無し３０分、５００℃加熱１０分、５００℃加熱３０分の順に、白金の担持量が増加することかわかる。白金の担持割合は、加熱無し３０分においては４．２％、５００℃加熱１０分では８．７％、５００℃加熱３０分では１３．６％と計算された。 Here, when the platinum is deposited for 30 minutes and 10 minutes by heating to 500 ° C. with the microheater of the susceptor 100, and without heating with the microheater, the temperature of the supercritical CO 2 is 100 ° C. as it is. FIG. 3 shows a spectrum obtained by XPS (X-ray photoelectron spectroscopy) when platinum is deposited for 30 minutes. Before the platinum supporting treatment (untreated CNW), platinum was not detected at all. However, since platinum was detected by the platinum supporting treatment, it can be understood that platinum was supported on the carbon nanowall. In addition, it can be seen that the amount of platinum supported increases in the order of 30 minutes with no heating, 10 minutes with 500 ° C. heating, and 30 minutes with 500 ° C. heating. The platinum loading ratio was calculated to be 4.2% for 30 minutes without heating, 8.7% for 10 minutes at 500 ° C. and 13.6% for 30 minutes at 500 ° C.

また、このようなカーボンナノウォールに担持された白金をＴＥＭ−ＥＤＸ（透過電子顕微鏡−エネルギー分散型Ｘ線分光器）により、元素を特定しながら画像を解析したところ、粒径が２．５ｎｍ前後の白金の粒子が検出された。その写真を図４に示す。黒い斑点が担持された白金粒子である。このように、本発明により、カーボンナノウォールの０．１μｍの間隔よりも十分小さい粒径の白金が担持されることが証明された。   In addition, when the platinum supported on such carbon nanowalls was analyzed by TEM-EDX (transmission electron microscope-energy dispersive X-ray spectrometer) while identifying the elements, the particle size was about 2.5 nm. Of platinum particles were detected. The photograph is shown in FIG. It is a platinum particle carrying black spots. Thus, according to the present invention, it was proved that platinum having a particle size sufficiently smaller than the 0.1 μm interval of the carbon nanowall was supported.

また、上記の処理をしたカーボンナノォウールの表面のＳＥＭ像を撮像した結果、図５、図６に示す写真が得られた。粒径１５０ｎｍの葡萄状の粒子群がウォールの上端面に析出しているのが分かる。この粒子の存在位置（図６におけるＣの位置）と、葡萄状粒子群の存在しない位置（図６におけるＢ）において、ＴＥＭ−ＥＤＸにより元素分析をした結果を図７、図８に示す。図７により葡萄状粒子は、ＣとＦとから成り、Ｐｔが存在しないことが理解される。また、葡萄状粒子群が存在しないところでは、図８から理解されるように、Ｃ原子のみが観測されていることが分かる。なお、Ｓｉはカーボンナノウォールを形成した基板の原子である。Ｐｔの粒子は、２．５ｎｍ以下と非常に小さく微量であるために、ＥＤＸでは観測されなかった。しかしながら、ＸＰＳによると、確実に、図３に示すように、Ｐｔの存在が確認された。このことから、カーボンナノウォールを形成した時に、Ｆ原子がウオールに存在し、このＦ原子に置換してＰｔがウォールに担持されると共に、ＣとＦの化合物が表面に析出したものと思われる。また、本実施例で得られた白金の担持されたカーボンナノウォールのＳＥＭ像は、図９に示すものである。   Moreover, as a result of imaging the SEM image of the surface of the carbon nano wool which performed said process, the photograph shown in FIG. 5, FIG. 6 was obtained. It can be seen that a soot-like particle group having a particle diameter of 150 nm is deposited on the upper end surface of the wall. FIG. 7 and FIG. 8 show the results of elemental analysis by TEM-EDX at the presence position of this particle (position C in FIG. 6) and the position where the saddle-shaped particle group does not exist (B in FIG. 6). It can be understood from FIG. 7 that the cage-like particles are composed of C and F and Pt does not exist. Moreover, it can be seen that only C atoms are observed where no soot-like particle group exists, as can be understood from FIG. Si is an atom of the substrate on which the carbon nanowall is formed. The Pt particles were very small and less than 2.5 nm, and were not observed by EDX. However, according to XPS, the presence of Pt was confirmed as shown in FIG. From this, it is considered that when carbon nanowalls are formed, F atoms are present in the wall, Pt is supported by the F atoms, and the compounds of C and F are precipitated on the surface. . Moreover, the SEM image of carbon nanowall carrying platinum obtained in this example is shown in FIG.

以上のように、粒径が２．５ｎｍ前後の白金の粒子が分散性良くカーボンナノウォールに担持されていることが分かった。この粒径は、カーボンナノウォールのウォール間の間隔０．１〜０．３μｍに比べて１／１００程度に小さいので、ウォール間の底部まで、十分に白金が担持されている。また、白金が担持されている箇所には、Ｆ原子が存在しなかったことから、Ｆ原子が白金と置換したものと考えられる。すなわち、カーボンナノウォールに白金を担持する場合の置換元素となるものと考えられる。このことから、このＦ原子は、他のハロゲン原子やその他の原子でも良いと思われる。したがって、このハロゲン原子などの置換元素のカーボンナノウォールにおける分散密度を制御できれば、白金の担持密度を制御できると考えられる。置換元素の分散密度を制御する方法としては、ハロゲンラジカルの量を制御してカーボンナノウォールに照射する方法や、水素ラジカルを照射して、ハロゲン元素に置換して、そのハロゲン元素の密度を減少させる方法などがある。その他光照射、任意のプラズマその他の粒子処理を行ったのちに、超臨界流体によって金属を担持させても良い。   As described above, it has been found that platinum particles having a particle size of about 2.5 nm are supported on the carbon nanowall with good dispersibility. This particle size is about 1/100 smaller than the interval between the wall of the carbon nanowalls of 0.1 to 0.3 μm, so that platinum is sufficiently supported up to the bottom between the walls. Moreover, since F atoms did not exist in the place where platinum was supported, it is considered that F atoms were substituted with platinum. That is, it is considered that it becomes a substitution element when platinum is supported on the carbon nanowall. From this, it seems that this F atom may be another halogen atom or another atom. Therefore, if the dispersion density in the carbon nanowall of a substitution element such as a halogen atom can be controlled, it is considered that the platinum loading density can be controlled. As a method for controlling the dispersion density of the substitution element, the amount of halogen radicals is controlled to irradiate the carbon nanowall, or the hydrogen radical is irradiated to substitute the halogen element to reduce the density of the halogen element. There is a method to make it. In addition, after performing light irradiation, arbitrary plasma, or other particle treatment, the metal may be supported by a supercritical fluid.

実施例では、白金を例に挙げて説明したが、超臨界溶液とし得る金属（有機金属など）であれば、上記した考察は、その金属に対しても、成立すると考えられるので、本件発明における金属は、白金に限定されず、任意の金属でも良い。要するに、本件発明を用いて初めてアスペクト比が大きなカーボンナノウォールにおいても、その底部まで、一様に分散して金属を担持させることができ、そのように粒径１０ｎｍ以下の金属を担持したカーボンナノウォールや、そのウォールの底部まで金属が担持できているカーボンナノウォールは新規な物質である。   In the examples, platinum has been described as an example. However, if the metal can be used as a supercritical solution (such as an organic metal), the above consideration is considered to be valid for the metal. The metal is not limited to platinum and may be any metal. In short, even for a carbon nanowall having a large aspect ratio for the first time using the present invention, it is possible to uniformly disperse a metal up to the bottom thereof, and thus carbon nanowalls carrying a metal having a particle size of 10 nm or less. Walls and carbon nanowalls in which metal is supported up to the bottom of the walls are novel materials.

上記実施例では撹拌槽と処理槽の２段構成の図２の処理装置を用いたが、これらを一体として用いても良い。また、図１のカーボンナノウォールの製造装置と図２の製造装置とを合体させた、図１０のような構成の製造装置を用いても良い。尚、図１０では、図１及び図２の構成部分と同一の機能を有する構成部分は同一の符号を付した。但し、図１の構成部分を流用する部分は加圧に耐えるものであるか適当な位置にバルブを設けて気密を保てるようにし、図２の構成部分を流用する部分は減圧に耐えるものであるか適当な位置にバルブを設けて気密を保てるようにしたものとする。   In the above-described embodiment, the processing apparatus of FIG. 2 having a two-stage configuration of a stirring tank and a processing tank is used, but these may be used integrally. Further, a manufacturing apparatus having a configuration as shown in FIG. 10 in which the carbon nanowall manufacturing apparatus of FIG. 1 and the manufacturing apparatus of FIG. 2 are combined may be used. In FIG. 10, constituent parts having the same functions as those shown in FIGS. 1 and 2 are given the same reference numerals. However, the part that diverts the component part of FIG. 1 is resistant to pressurization or is provided with a valve at an appropriate position so as to maintain airtightness, and the part that diverts the component part of FIG. 2 is resistant to decompression. Alternatively, a valve is provided at an appropriate position so that airtightness can be maintained.

本発明は、金属触媒を担持させたカーボンナノウォールを提供するものであり、化学品の製造、加工及び処理、混合物中の汚染物の分解及び除去その他の様々な用途に適用することができる。特にカーボンナノウォールの電気伝導性を生かした用途、例えばプロトン交換膜（ＰＥＭ）を用いた燃料電池の正負電極として有望である。   The present invention provides a carbon nanowall carrying a metal catalyst, and can be applied to various uses such as chemical production, processing and treatment, decomposition and removal of contaminants in a mixture, and the like. In particular, it is promising as a positive and negative electrode of a fuel cell using a carbon nanowall, for example, a proton exchange membrane (PEM).

カーボンナノウォールの製造装置の一例を示す構成図。The block diagram which shows an example of the manufacturing apparatus of carbon nanowall. 本発明の具体的な一実施例に係る白金担持カーボンナノウォールの製造装置の構成図。The block diagram of the manufacturing apparatus of the platinum carrying | support carbon nanowall which concerns on one specific Example of this invention. 白金担持カーボンナノウォールのＸＰＳによるスペクトル図。The spectrum figure by XPS of carbon nanowall which carried platinum. 本実施例の処理をしたカーボンナノウォールのＴＥＭ−ＥＤＸによる写真。The photograph by TEM-EDX of the carbon nanowall which processed the present Example. 本実施例の処理をしたカーボンナノウォールのＳＥＭによる写真。The photograph by SEM of the carbon nanowall which processed the present Example. 図５のＳＥＭ像の葡萄状粒子領域内のＡ点と、その領域外のＢ点の位置を表示するための図。FIG. 6 is a diagram for displaying the position of point A within the bowl-shaped particle region of the SEM image of FIG. 5 and the position of point B outside the region. ＳＥＭによる写真におけるＡ点のＴＥＭ−ＥＤＸによる測定結果。The measurement result by TEM-EDX of A point in the photograph by SEM. ＳＥＭによる写真におけるＢ点のＴＥＭ−ＥＤＸによる測定結果。The measurement result by TEM-EDX of B point in the photograph by SEM. 本実施例の処理をしたカーボンナノウォールの上面のＳＥＭによる写真。The photograph by the SEM of the upper surface of the carbon nanowall processed by the present Example. 図１及び図２の製造装置を一体化した製造装置の構成を示す構成図。The block diagram which shows the structure of the manufacturing apparatus which integrated the manufacturing apparatus of FIG.1 and FIG.2.

１００：反応槽
２１０：バルブ
２００：撹拌槽 100: reaction tank 210: valve 200: stirring tank

Claims (7)

金属を担持させたカーボンナノウォールの製造方法であって、
予め基板に形成したカーボンナノウォールに、前記金属の化合物を超臨界流体に溶解した状態で接触処理する処理工程を有し、
前記処理工程の際に、３００〜８００℃にカーボンナノウォールを加熱する
ことを特徴とする金属を担持させたカーボンナノウォールの製造方法。 A method for producing a carbon nanowall carrying a metal,
In advance carbon nano-wall formed on the substrate, we have a process step of contact treatment while dissolving a compound of the metal in the supercritical fluid,
A method for producing a carbon nanowall carrying a metal, wherein the carbon nanowall is heated to 300 to 800C during the treatment step . 金属を担持させたカーボンナノウォールの製造方法であって、
予め基板に形成したカーボンナノウォールに、前記金属の化合物を超臨界流体に溶解した状態で接触処理する処理工程を有し、
前記金属は白金であることを特徴とする金属を担持させたカーボンナノウォールの製造方法。 A method for producing a carbon nanowall carrying a metal,
The carbon nanowall formed in advance on the substrate has a treatment process in which the metal compound is contact-treated in a state of being dissolved in a supercritical fluid,
Method for producing a carbon nano-wall obtained by supporting the metallic, wherein the metal is platinum. 金属を担持させたカーボンナノウォールの製造方法であって、
予め基板に形成したカーボンナノウォールに、前記金属の化合物を超臨界流体に溶解した状態で接触処理する処理工程を有し、
前記超臨界流体は二酸化炭素であることを特徴とする金属を担持させたカーボンナノウォールの製造方法。 A method for producing a carbon nanowall carrying a metal,
The carbon nanowall formed in advance on the substrate has a treatment process in which the metal compound is contact-treated in a state of being dissolved in a supercritical fluid,
Method for producing a carbon nano-wall obtained by supporting the metallic, wherein the supercritical fluid is carbon dioxide. 前記処理工程の際に、３００〜８００℃にカーボンナノウォールを加熱することを特徴とする請求項２又は請求項３に記載の金属を担持させたカーボンナノウォールの製造方法。 The method for producing a carbon nanowall carrying a metal according to claim 2 or 3 , wherein the carbon nanowall is heated to 300 to 800 ° C during the treatment step. 前記金属の化合物は、有機金属錯体又は有機金属化合物であることを特徴とする請求項１乃至請求項４の何れか１項に記載の金属を担持させたカーボンナノウォールの製造方法。 The method for producing a carbon nanowall carrying a metal according to any one of claims 1 to 4, wherein the metal compound is an organometallic complex or an organometallic compound. 前記金属はカーボンナノウォールの有する水素原子又はハロゲン原子に置換してカーボンナノウォールに担持されることを特徴とする請求項１乃至請求項５の何れか１項に記載の金属を担持させたカーボンナノウォールの製造方法。 6. The carbon carrying a metal according to claim 1, wherein the metal is carried on the carbon nanowall after being replaced by a hydrogen atom or a halogen atom contained in the carbon nanowall. Manufacturing method of nanowall. 前記ハロゲン原子はフッ素であることを特徴とする請求項６に記載の金属を担持させたカーボンナノウォールの製造方法。 The method for producing a carbon nanowall carrying a metal according to claim 6, wherein the halogen atom is fluorine.
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