JP2008231502A - Powder agitation mechanism, method for producing metallic particulate carrying powder and catalyst for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a powder agitation mechanism using a coaxial type vacuum arc vapor deposition apparatus for uniformly carrying metallic particulates on the entire surface of the powder, a production method of the metallic particulate carrying powder, and a catalyst for a fuel cell. <P>SOLUTION: The powder agitation mechanism has a striking member 3 disposed near the upper part of a container 1 for the powder and an oscillation mechanism for oscillating the container for striking the container against the striking member. The metallic particulate carrying powder is produced by using the coaxial type vacuum arc vapor deposition apparatus equipped with the agitation mechanism and the coaxial type vacuum arc vapor deposition apparatus and the coaxial type vacuum arc vapor deposition source. The catalyst for the fuel cell comprising the metallic particulate carrying powder is provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a powder agitation mechanism, a method for producing metal fine particle-supported powder, and a catalyst for a fuel cell, and in particular, a powder agitation mechanism provided in a coaxial vacuum arc vapor deposition apparatus, and a metal fine particle-supported powder using this vapor deposition apparatus The present invention relates to a production method and a fuel cell catalyst obtained by using this production method.

  Conventionally, for example, metal fine particles serving as an electrode catalyst for a fuel cell are supported on the surface of a powder serving as a substrate by a liquid phase method such as a precipitation method, a photodeposition method, or a coprecipitation method. In this case, it is necessary to uniformly disperse and support the metal fine particles serving as a catalyst on the powder, but there is a problem that the catalyst performance varies depending on the method of the support.

  Catalyst loading by the above liquid phase method has to go through steps such as reduction treatment, filtration treatment, and high temperature treatment at about 800 ° C., and it takes time to carry the catalyst. Further, since it is necessary to perform a reduction treatment or a high temperature treatment, the deposited metal fine particles are oxidized, so that there is a problem that the catalyst performance is deteriorated, for example, the power generation performance of the fuel cell is lowered.

  In addition to the above method, a method of supporting a catalytic metal using a vapor phase method by sputtering or vapor deposition is also known. In this case, the powder is put in a container such as a sample pan placed on the substrate, and the catalyst metal is irradiated on the powder and supported on the powder. Thus, it was necessary to take out the container after carrying it on one side in this way, so that the powder was turned upside down, and again irradiate and carry the catalyst metal thereon. In this case, it is conceivable to stir the powder by shaking the container containing the powder, but just by shaking the container, the powder does not roll on the bottom of the container, but simply slides on the bottom. There is a problem that metal fine particles cannot be supported on the entire surface of the powder.

A fuel cell catalyst is known in which metal fine particles are supported on conductive particles such as carbon particles (see, for example, Patent Document 1). In this case, a method is used in which the conductive particles and the metal fine particles are simultaneously evaporated by AC arc discharge, and the metal fine particles are completely or partially embedded in the conductive particles.
JP 2006-140017 (Claims, paragraph 0019, etc.)

  An object of the present invention is to solve the above-mentioned problems of the prior art, a powder stirring mechanism provided in a coaxial vacuum arc vapor deposition apparatus, a method for producing metal fine particle-supported powder using this vapor deposition apparatus, and this An object of the present invention is to provide a fuel cell catalyst obtained by using the production method.

  The powder agitation mechanism of the present invention includes a cylindrical trigger electrode, a cylindrical cathode electrode having at least a tip portion made of a metal material for producing fine particles, and a coaxial arrangement around the trigger electrode and the cathode electrode. A coaxial vacuum arc provided with a coaxial vacuum arc evaporation source, wherein the trigger electrode and the cathode electrode are disposed adjacent to each other with a disc-shaped insulator interposed therebetween. A powder agitation mechanism provided in the vapor deposition apparatus, wherein the powder agitation mechanism is provided in the vicinity of the upper part of the powder container for charging the powder for vapor-depositing fine particles made of the metal material. It has a member and a rocking mechanism for rocking the powder container in order to abut the powder container against the butting member.

  It is preferable that the powder container is provided with a rib having a height of 5 mm or less on the bottom surface. When the height exceeds 5 mm, when the powder agitation mechanism is tilted, depending on the angle of the tilt, the powder cannot get over the ribs and roll, and metal fine particles are supported on the entire surface of the powder. I can't.

  The abutting member is preferably provided in the vicinity of the tip of the anode electrode of the coaxial vacuum arc deposition source.

  You may comprise so that the outer edge part of the anode electrode front-end | tip of the said coaxial type vacuum arc vapor deposition source may function as the said abutting member, without providing the said abutting member.

  The method for producing a metal fine particle-supported powder of the present invention comprises a cylindrical trigger electrode, a cylindrical cathode electrode having at least a tip portion made of a metal material for producing fine particles, and coaxial around the trigger electrode and the cathode electrode. A coaxial vacuum arc evaporation source having a cylindrical anode electrode arranged in a shape, the trigger electrode and the cathode electrode being arranged adjacent to each other with a disc-shaped insulator interposed therebetween, and a bottom surface of 5 mm or less From the abutting member provided in the vicinity of the upper part of the powder container provided with the rib, and the swing mechanism for swinging the powder container in order to abut the powder container against the abutting member Using a coaxial vacuum arc deposition apparatus equipped with a powder agitation mechanism, and generating a trigger discharge between the trigger electrode and the anode electrode in a pulsed manner between the cathode electrode and the anode electrode. A static vapor deposition step of intermittently inducing a spark discharge to deposit plasma-form fine metal particles generated from the metal material of the cathode electrode on the powder charged in the powder container; While the body is stirred by the powder stirring mechanism, the stirring and vapor deposition step of depositing the plasma-formed metal fine particles on the powder is repeated so that the metal fine particles are supported on the powder surface.

  The agitation is performed by abutting the upper edge portion of the powder container against the abutting member, and by physical impact thereof. Also, the coaxial vacuum arc deposition provided with the powder agitating mechanism not including the abutting member. In the case of using an apparatus, the agitation is performed by abutting a powder container against the outer edge of the tip of the anode electrode of the coaxial vacuum arc deposition source.

  The supported metal fine particles have a particle size of 1 to 10 nm. By using a vapor deposition apparatus equipped with a coaxial arc vacuum vapor deposition source and a powder stirring mechanism as described above, metal fine particles having such a particle size can be controlled and produced.

  The powder is preferably at least one selected from powders of carbon such as carbon black, aluminum oxide, silicon oxide and titanium oxide.

  The fuel cell catalyst of the present invention is characterized in that metal fine particles are supported as a metal catalyst on the surface of a carbon powder having a particle size of 10 to 100 nm in accordance with the method for producing a metal fine particle-supported powder. The particle size of the metal fine particles supported on the surface of the carbon powder is 1 to 10 nm. As described above, since the uniform fine metal catalyst having a predetermined particle diameter is supported on the surface of the carbon powder, the electric characteristics (oxidation-reduction reaction) of the fuel cell can be improved.

  By using the coaxial vacuum arc deposition apparatus equipped with the powder agitation mechanism of the present invention, it is possible to carry fine metal particles evenly on the entire surface of the powder as well as on one side of the powder. For example, an electrode catalyst such as fuel electricity As a result, it is possible to provide a catalyst material capable of exhibiting sufficient performance.

  Further, according to the fuel cell catalyst of the present invention, since the uniform fine metal catalyst having a predetermined particle size is supported on the surface of the carbon powder, the electrical characteristics (oxidation-reduction reaction) of the fuel cell are improved. There is an effect.

  According to one embodiment of the powder agitation mechanism according to the present invention, the abutting member (obstacle) provided near the upper part of the powder container in which the powder for depositing the fine particles made of the metal material is deposited. ) And a rocking mechanism for rocking the powder container to abut the upper edge of the powder container against the butting member. A rib having a predetermined height is provided on the bottom surface of.

  The swing mechanism is not particularly limited as long as the powder container can swing left and right like a cradle and the upper edge of the container can be abutted against the abutting member. What is necessary is just to have.

  The abutting member may be provided above the powder container so that the powder container is abutted and the powder can be uniformly stirred. In this case, the position where the abutting member is provided may be appropriately set in consideration of the size of the cross section of the powder container. For example, the abutting member may be provided in the vicinity of the tip of the anode electrode of the coaxial vacuum arc deposition apparatus, and the outer edge of the anode electrode of the coaxial vacuum arc deposition apparatus itself is the abutting member. You may comprise so that it may function as a member. The abutting member and the anode electrode may be made of a material having a hardness equal to or higher than that of the powder container.

  Hereinafter, an embodiment of a powder stirring mechanism according to the present invention will be described in detail with reference to FIGS. FIG. 1A is a cross-sectional view schematically showing a cross-section of a vacuum chamber incorporating a powder stirring mechanism, and FIG. 1B is a schematic side view of FIG. FIG. 2A is a schematic top view of the powder container, and FIG. 2B is a schematic cross-sectional view of the powder container.

  As schematically shown in FIGS. 1 and 2, the powder agitation mechanism of the present invention is in the vicinity of the upper part of the powder container 1 in which the powder S is charged (in FIG. 1, the anode of the coaxial vacuum arc evaporation source 2). The cylindrical abutting member 3 provided in the vicinity of the outer periphery of the electrode) and a known rocking mechanism (not shown). The powder container 1 has a shape such as a dish, and is a powder container. It is mounted on the mounting table 4. This swinging mechanism is a known swinging mechanism that swings the powder container 1 left and right with its center as a fulcrum, so that the upper edge of the powder container abuts against the abutting member 3. is there. The shape of the abutting member 3 is not limited to a cylindrical shape, and any shape is acceptable as long as the upper edge of the powder container 1 abuts and the powder S can be rolled and stirred by the physical impact. For example, a plate shape may be used. In FIG. 1, 5 indicates a vacuum chamber. The bottom surface of the powder container 1 is generally provided with a plurality of ribs 1a having a height of 5 mm or less, preferably 1 to 5 mm, more preferably 1 to 2 mm. Although the height of the ribs depends on the angle at which the ribs are swung, the powder can overcome the ribs and achieve good rolling so that the powder rolls well, that is, the powder container swings. As such, it may be selected as appropriate.

  Next, an embodiment of a coaxial arc vacuum deposition apparatus equipped with the powder stirring mechanism and a method for producing metal fine particles of the present invention using this deposition apparatus will be described in detail with reference to FIG.

  As shown in FIG. 3, the coaxial vacuum arc deposition apparatus 31 has a cylindrical vacuum chamber 32, and a powder container mounting table 33 is horizontally disposed below the vacuum chamber. Although not shown, the vacuum chamber 32 is provided with a known rocking mechanism for rocking the powder container 34 mounted on the container mounting table 33.

  The container mounting table may be provided with heating means (not shown) such as a heater so that the powder S in the powder container 34 can be heated so that the powder can be heated to a predetermined temperature if desired. . One or a plurality of mounting tables 33 are provided, and a powder container 34 can be held and attached to each. Above the inside of the vacuum chamber 32, one or a plurality of later-described coaxial type vacuum arc vapor deposition sources (arc plasma guns) 35 face the respective powder containers 34, and the cathode electrode 35a side faces the container mounting table 33. It is arranged toward the. Thereby, the metal fine particles can fly from the upper side to the lower side in the vacuum chamber 32, and can be deposited on the powder S in the powder container 34. If necessary, the powder container 34 is made of the above-described powder. The powder S is agitated by being swung by a stirring mechanism so that metal fine particles can be uniformly deposited on the surface of the powder S.

A gas introduction system 36 and a vacuum exhaust system 37 are connected to the wall surface of the vacuum chamber 32. In the gas introduction system 36, a valve 36a, a mass flow controller 36b, and a gas cylinder 36c are connected in this order by metal piping. The vacuum exhaust system 37 includes a valve 37a, a turbo molecular pump 37b, a valve 37c, and a rotary pump 37d connected in this order by a metal vacuum pipe, and the vacuum chamber 32 is preferably evacuated to 10 ⁻⁵ Pa or less. It is configured to allow exhaust.

  As shown in FIG. 3, the coaxial vacuum arc deposition source 35 provided in the coaxial vacuum arc deposition apparatus 31 has one end closed and the other end facing the powder container 34 opened, and platinum, From a cylindrical cathode electrode 35a made of a metal material for vapor deposition selected from cobalt, iron, nickel, ruthenium, titanium, etc., a cylindrical anode electrode 35b made of stainless steel, etc., and from stainless steel etc. A disc-shaped trigger electrode (for example, a ring-shaped trigger electrode) 35c, and a disc-shaped insulator 35d provided to separate the cathode electrode 35a and the trigger electrode 35c from each other; It is composed of A cathode electrode 35 a is provided to face the powder container 34. Although not shown, the three components of the cathode electrode 35a, the insulator 35d, and the trigger electrode 35c are attached in close contact with screws or the like. Although not shown, the anode electrode 35 b is attached to a vacuum flange by a support column, and this vacuum flange is attached to the upper surface of the vacuum chamber 32. The cathode electrode 35a is provided coaxially inside the anode electrode 35b and separated from the wall surface of the anode electrode by a certain distance. As described above, at least the tip of the cathode electrode 35a (corresponding to the end of the anode electrode 35b on the opening A side) may be made of the metal material.

  The trigger electrode 35c is attached with an insulator (washer insulator) 35d made of alumina or the like sandwiched between the target material or the cathode electrode 35a. The insulator 35d is attached so as to insulate the cathode electrode 35a from the trigger electrode 35c, and the trigger electrode 35c may be attached to the cathode electrode 35a via an insulator. These anode electrode 35b, cathode electrode 35a, and trigger electrode 35c are preferably electrically insulated by an insulator 35d and an insulator. The insulator 35d and the insulator may be configured integrally or may be configured separately.

  A trigger power source 35e composed of a pulse transformer is connected between the cathode electrode 35a and the trigger electrode 35c, and an arc power source 35f is connected between the cathode electrode 35a and the anode electrode 35b. The arc power source 35f includes a DC voltage source 35g and a capacitor unit 35h. Both ends of the capacitor unit 35h are connected to a cathode electrode 35a and an anode electrode 35b, respectively. The capacitor unit 35h and the DC voltage source 35g are connected in parallel. It is connected.

  The capacitor unit 35h is connected to one or a plurality of capacitors (one capacitor is illustrated in FIG. 3), and one capacitor thereof is, for example, 2200 μF (withstand voltage 160V), The battery is charged at any time by the DC voltage source 35g. The trigger power supply 35e transforms the pulse voltage of the input 200V to about 17 times, and outputs 3.4 kV (several μA) and polarity: plus. The arc power supply 35f is a DC power supply having a capacity of 100 V and several A, and charges a capacitor unit 35h (for example, 8800 μF in the case of four capacitor units) from the DC voltage source 35g. Since this charging time takes about 1 second, the period when discharging is repeated at 8800 μF in this system is 1 Hz. The positive output terminal of the trigger power supply 35e is connected to the trigger electrode 35c, and the negative terminal is connected to the same potential as the negative output terminal of the DC voltage source 35g of the arc power supply 35f, and is connected to the cathode electrode 35a. The plus terminal of the DC voltage source 35g of the arc power supply 35f is grounded to the ground potential and connected to the anode electrode 35b. Both terminals of the capacitor unit 35h are connected between the plus terminal and the minus terminal of the DC voltage source 35g. In FIG. 3, reference numeral 35i denotes a cable, and the flow of the discharge current during discharge is indicated by an arrow →. Actually, since most of the discharge current is due to electrons, the actual flow direction of electrons is opposite to the direction of the arrow. However, in FIG. 3, the electric circuit is simply shown as an electric circuit diagram. , Shown as the direction of current flow.

  Next, a process for supporting metal fine particles on the surface of the powder S charged in the powder container 34 using the coaxial vacuum arc deposition apparatus 31 shown in FIG. 3 will be described.

  For example, first, the capacitor unit 35h is charged with 100V to 400V by the DC voltage source 35g, the capacity of the capacitor unit 35h is set to 8800 μF or less, the intermittent operation cycle is set to 1 to 5 Hz, and the discharge time is set to 1000 μs or less. Next, a pulse voltage is output from the trigger power source 35e to the trigger electrode 35c (output: 3.4 kV), and is applied between the cathode electrode 35a and the trigger electrode 35c via a washer insulator 35d. Trigger discharge (creeping discharge on the washer insulator surface) is generated between the electrode 35c. At this time, electrons are generated from the joint between the cathode electrode 35a and the washer insulator 35d. By this trigger discharge, the electric charge stored in the capacitor unit 35h is vacuum-arced between the side surface of the cathode electrode 35a and the inner surface of the anode electrode 35b, and a large amount of arc current flows into the cathode electrode 35a. Then, plasma of a metal material such as platinum is formed from the cathode electrode 35a. Discharging is stopped by the discharge of the electric charge stored in the capacitor unit 35h. It is preferable to repeat this trigger discharge a plurality of times and induce arc discharge for each trigger discharge.

  During the above-described arc discharge, fine particles (atomic ions, clusters, electrons, etc. that are turned into plasma) generated by melting the metal material are formed. The fine particles are discharged into the vacuum chamber 32 from the opening (discharge port) A of the anode electrode 35b, and the powder S in the powder container 34 installed facing the opening A is subjected to the above-described operation. The metal fine particles formed as described above are supplied, and the metal fine particles are adhered to the powder S and aggregated to form particles on which metal fine particles having a diameter of several nm (for example, 1 to 10 nm) are adhered and carried. The powder S may be at room temperature or heated to a predetermined temperature by a heating means.

  According to the present embodiment, metal particles having a size of about 1 to 10 nm are formed by using the above-described discharge conditions using a capacitor unit 35h attached in the vicinity of the coaxial vacuum arc deposition source 35. In addition, the fine metal particles can be adhered to and supported on the powder with good adhesion. When the capacitor unit 35h is attached in the vicinity of the coaxial vacuum arc vapor deposition source 35, the connection line between the cathode electrode 35a and the anode electrode 35b is short, for example, 100 mm or less, preferably 10 mm to 100 mm. good.

  The metal fine particles are released as follows. Since a large amount of current flows through the cathode electrode 35a, a magnetic field is formed at the cathode electrode 35a, and electrons in the plasma generated at this time (the electrons fly from the cathode electrode 35a to the cylindrical inner surface of the anode electrode 35b) are self-formed. It receives Lorentz force by the magnetic field and flies forward. On the other hand, the metal ions of the cathode electrode material in the plasma fly forward so that the electrons fly and polarize as described above, and are attracted to the electrons ahead by the Coulomb force. It will adhere and be carried.

  During the above-described arc discharge, fine particles (such as plasma-generated atomic ions, clusters, and electrons) formed by melting of a metal such as platinum are formed. The fine particles are discharged from the opening A of the anode electrode 35a into the vacuum chamber 32 and supplied onto the carbon black S charged in the powder container 34. First, the powder S is stirred at room temperature without stirring. The step of depositing statically with the number of shots and the step of depositing the powder S with a predetermined number of shots at room temperature while stirring as described above are then repeated a predetermined number of times to deposit the platinum on the carbon black surface. Supports metal fine particles. During stirring, the upper edge of the powder container 34 is abutted against an abutting member (not shown) or the tip of the anode electrode 35b, and a physical impact is applied to the container so that the powder S is contained in the container. Stir while rolling over the ribs on the bottom. That is, the metal fine particles are vapor-deposited by a step in which metal fine particles are statically vapor-deposited on the powder surface with a predetermined number of shots without stirring the powder S, and then the metal fine particles are deposited on the powder surface while stirring the powder S The process of stirring and vapor deposition with a predetermined number of shots is alternately repeated a plurality of times.

  By depositing metal catalyst particles such as platinum on powder (carbon black) for fuel cell electrodes using the coaxial vacuum arc deposition source 35 as described above, platinum or the like is deposited on the powder, for example, with a particle size of 2 to 2. Since it is formed and supported at about 5 nm, the electrical characteristics (oxidation-reduction reaction) of the fuel cell are improved when the powder supported by platinum or the like is used as a fuel cell electrode.

  In the above embodiment, the powder charged in the container is arranged facing the coaxial vacuum arc vapor deposition source, and the metal fine particles are directly vapor deposited on the powder. When arranged vertically with respect to the powder, μ-size particles (droplets) may be mixed into the powder from the vapor deposition source. In this case, a coaxial vacuum arc deposition source is mounted in a horizontal state with respect to the vacuum chamber, two magnets are arranged in parallel so as to be sandwiched in the vicinity of the anode electrode, a magnetic field is formed, plasma is deflected, and powder Metal fine particles may be vapor-deposited.

  In this example, a coaxial vacuum arc deposition source 31 provided with a coaxial vacuum arc deposition source 35 and a known powder stirring mechanism (not shown) shown in FIG. 3 was used, and the target material was composed of platinum. A carbon black powder (Cabot Corp.) placed in a powder container 34 (having four ribs with a height of 1 mm on the bottom surface) having a diameter of 80 mm × 10 mm as shown in FIG. (Product name: VULCAN XC-72, particle size 20-50 nm) was supported with platinum fine particles at room temperature. In addition, the distance from the tip (opening A) of the anode electrode 35b to the carbon black powder was set to about 40 mm.

  First, before forming the platinum fine particles, the DC voltage source 35g charges the capacitor unit 35h (four capacitors are provided in this embodiment), the arc voltage is set to 100V, and the capacitance of the capacitor unit 35h is set to 8800 μF. Set. Next, a pulse voltage is output from the trigger power source 35e to the trigger electrode 35c (output: 3.4 kV), and is applied between the cathode electrode 35a and the trigger electrode 35c via a washer insulator 35d. Trigger discharge was generated between the electrode 35c. Electrons were generated from the joint between the cathode electrode 35a and the washer insulator 35d. At this time, the electric charge stored in the capacitor unit 35h is arc-discharged between the side surface of the cathode electrode 35a and the inner surface of the anode electrode 35b, a large amount of current flows into the cathode electrode 35a, and platinum plasma is formed from the cathode electrode 35a. It was done. Discharging stopped due to the discharge of the electric charge stored in the capacitor unit 35h. The discharge cycle was 1 Hz, and the discharge was repeated, and an arc discharge was induced for each trigger discharge.

  During the arc discharge described above, fine particles (such as atomized ions, clusters, electrons, etc. that were turned into plasma) formed by the melting of platinum were formed. The fine particles are discharged from the opening A of the anode electrode 35a into the vacuum chamber 32 and supplied onto the carbon black S charged in the powder container 34. First, the powder S is generated at 400 room temperature without stirring. (Shot) Static deposition was performed, and then the powder container 34 was swung by the powder stirring mechanism, and the upper edge of the container was abutted against the tip of the cathode electrode 35b while stirring the powder S at room temperature. Two static / stirred vapor deposition steps of 100 shot stirring vapor deposition were repeated 10 times to perform a total of 5000 shot vapor deposition steps, and platinum fine particles were supported on the carbon black surface. When stirring, the upper edge of the powder container 34 is abutted against the tip of the anode electrode 35a and a physical impact is applied to the container, so that the carbon black S rolls over the rib provided on the bottom of the container. While stirring, it was confirmed.

FIG. 4 shows a TEM photograph of particles in which platinum fine particles are supported on the carbon black powder thus obtained. As is apparent from FIG. 4, it can be seen that platinum fine particles of 2 to 5 nm are uniformly dispersed and supported on the carbon black powder. This carbon black carrying platinum fine particles is useful as an electrode of a fuel cell.
(Comparative Example 1)

  The same carbon black powder S as in Example 1 was fixed on a glass plate, and platinum fine particles were supported on the surface of the carbon black powder S under the same conditions as in Example 1 without stirring. However, when the powder was fixed and the deposition was carried out without increasing the number of shots, a thin film was formed, so 50 shots were deposited.

  FIG. 5 shows a TEM photograph of particles in which platinum fine particles are supported on the carbon black powder thus obtained. As is apparent from FIG. 5, it can be seen that platinum fine particles are supported only on the surface of the carbon black powder to which the platinum fine particles are supplied.

  As is clear from Example 1 and Comparative Example 1 above, by using the coaxial vacuum arc deposition apparatus equipped with the powder agitation mechanism of the present invention, the metal fine particles can be uniformly and uniformly supported on the entire surface of the powder. It can be seen that the performance as a catalyst can be improved.

  Particles in which platinum fine particles are supported on carbon black powder formed according to Example 1 are used as an electrode catalyst for a fuel cell. Electricity using a known convection voltammetry method (rotating disk electrode method) is used for this electrode catalyst. The current value obtained by the oxidation-reduction reaction was measured by chemical measurement. The measurement conditions were a sweep speed of 50 mV / sec and a rotation speed of 2000 rpm. For comparison, only carbon black (CB) is used, and as an electrode catalyst in which platinum is supported on carbon black by a conventional liquid phase process, a commercially available product: Pt 20 wt% / CB (manufactured by ElectroChem, Inc.). Similarly, electrochemical measurements were performed.

  The current value data measured as described above is plotted in FIG. 6 with the horizontal axis representing potential (V vsAg / AgCl) and the vertical axis representing current (A) (in FIG. 6, CB is carbon black, APG). -Pt5000 / CB) is the electrocatalyst obtained in Example 1 above, and Pt20 wt% / CB is the data for a commercial product).

  As is apparent from FIG. 6, the electrode catalyst obtained by vapor deposition using the coaxial vacuum arc vapor deposition source apparatus according to the present invention has a current value higher than that of the electrode catalyst containing 20 wt% of platinum in carbon black. It can be seen that the catalyst activity is higher and higher.

  According to the present invention, by using a coaxial vacuum arc vapor deposition apparatus equipped with a powder stirring mechanism, it is possible to uniformly and uniformly carry metal fine particles on the entire surface of the powder. By utilizing this method, the metal fine particles obtained by vapor-depositing the catalyst metal consisting of uniform metal fine particles on the powder (carbon black) for the fuel cell electrode, the uniform metal catalyst is supported on the carbon black. Therefore, the use of this metal catalyst improves the electrical characteristics (oxidation-reduction reaction) of the fuel cell.

  Therefore, the present invention can be used for supporting a catalyst metal in the technical field of next-generation energy devices such as fuel cells. In addition, since the present invention can form particles carrying uniform metal fine particles on the powder surface as described above, it can also be used in the technical field of producing a base film (catalyst layer) of a nanocarbon material such as carbon nanotubes. .

It is a schematic diagram showing an embodiment of a powder stirring mechanism according to the present invention, (a) is a cross-sectional view schematically showing a cross section of a vacuum chamber incorporating a powder stirring mechanism, (b) is ( It is a typical side view of a). FIG. 3 is a schematic view of a powder container used in the powder stirring mechanism of the present invention, (a) is a top view of the powder container, and (b) is a cross-sectional view of the powder container. The block diagram which shows typically the example of 1 structure of the coaxial arc vacuum evaporation system provided with the powder stirring mechanism of this invention. 4 is a TEM photograph of particles in which platinum fine particles are supported on the carbon black powder obtained in Example 1. FIG. 4 is a TEM photograph of particles in which platinum fine particles are supported on the carbon black powder obtained in Comparative Example 1. FIG. 6 is a graph showing the catalytic activity of a fuel cell electrode catalyst in Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Container for powder 2 Coaxial type vacuum arc vapor deposition source 3 Butting member 4 Powder container mounting base 5 Vacuum chamber 1a Rib S Powder 31 Coaxial vacuum arc vapor deposition apparatus 32 Vacuum chamber 33 Container mounting base 34 Powder container 35 Coaxial vacuum arc deposition source 35a Cathode electrode 35b Anode electrode 35c Trigger electrode 35d Insulator 35e Trigger power supply 35f Arc power supply 35g DC voltage source 35h Capacitor unit 35i Cable 36 Gas introduction system 36a Valve 36b Mass flow controller 36c Gas cylinder 37 Vacuum exhaust system 37a Valve 37b Turbo molecular pump 37c Valve 37d Rotary pump A Opening

Claims (11)

A cylindrical trigger electrode, a cylindrical cathode electrode having at least a tip made of a metal material for producing fine particles, and a cylindrical anode electrode coaxially disposed around the trigger electrode and the cathode electrode Powder agitation provided in a coaxial vacuum arc vapor deposition apparatus having a coaxial vacuum arc vapor deposition source, the trigger electrode and the cathode electrode being disposed adjacent to each other with a disc-shaped insulator interposed therebetween And a powder agitating mechanism provided with an abutting member provided in the vicinity of an upper part of a powder container in which powder for depositing fine particles of the metal material is deposited, and a powder on the abutting member. And a rocking mechanism for rocking the powder container to abut the container. The powder agitation mechanism according to claim 1, wherein the powder container is provided with a rib having a height of 5 mm or less on a bottom surface thereof. The powder agitation mechanism according to claim 1 or 2, wherein the abutting member is provided in the vicinity of the tip of the anode electrode of the coaxial vacuum arc deposition source. 3. The powder agitation according to claim 1, wherein the outer edge portion of the tip of the anode electrode of the coaxial vacuum arc deposition source functions as an abutting member without providing the abutting member. mechanism. A cylindrical trigger electrode, a cylindrical cathode electrode having at least a tip portion made of a metal material for producing fine particles, and a cylindrical anode electrode arranged coaxially around the trigger electrode and the cathode electrode A coaxial vacuum arc evaporation source in which the trigger electrode and the cathode electrode are disposed adjacent to each other with a disc-shaped insulator interposed therebetween, and a powder container provided with a rib of 5 mm or less on the bottom surface A coaxial vacuum comprising an abutting member provided in the vicinity and a powder agitating mechanism comprising an oscillating mechanism for oscillating the powder container to abut the abutting member against the powder container Using an arc evaporation apparatus, a trigger discharge is generated in a pulse manner between the trigger electrode and the anode electrode, and an arc discharge is intermittently induced between the cathode electrode and the anode electrode, and the cathode A stationary vapor deposition step of depositing plasma-formed metal fine particles generated from the metal material of the electrode on the powder charged in the powder container, and then stirring the powder by the powder stirring mechanism, A method for producing a metal fine particle-supported powder, wherein the metal fine particles are supported on the powder surface by repeating the stirring vapor deposition step of depositing the plasma-formed metal fine particles on the powder. 6. The method for producing metal fine particle-supported powder according to claim 5, wherein the stirring is performed by abutting the upper edge portion of the powder container against the abutting member and by physical impact thereof. In the case of using a coaxial vacuum arc vapor deposition apparatus equipped with a powder agitation mechanism that does not include the abutting member, the agitation pushes the powder container into the outer edge of the anode electrode tip of the coaxial vacuum arc vapor deposition source. 6. The method for producing a metal fine particle-supported powder according to claim 5, wherein the method is carried out by contact. The method for producing a metal fine particle-supported powder according to any one of claims 5 to 7, wherein a particle diameter of the supported metal fine particle is 1 to 10 nm. 9. The metal fine particle-supported powder according to claim 5, wherein the powder is at least one selected from carbon, aluminum oxide, silicon oxide, and titanium oxide powder. Method. A fuel cell comprising metal fine particles supported as a metal catalyst on the surface of a carbon powder having a particle size of 10 to 100 nm according to the method for producing a metal fine particle-supported powder according to claim 5. Catalyst. 11. The fuel cell catalyst according to claim 10, wherein the metal fine particles have a particle size of 1 to 10 nm.