JP3983239B2 - Method for producing carbon nanotube - Google Patents

Description

It relates to a manufacturing method of the present invention the carbon nanotubes, microparticles particularly relates to a process for the preparation of supported carbon nanotubes.

  Due to its unique mechanical, electrical, and thermal properties, applications of carbon nanotubes are currently being studied in various fields. Attempts have also been made to modify carbon nanotubes in various forms and add new functions to them, one of which is to attempt to support fine particles on carbon nanotubes.

  For example, an example in which carbon nanotubes are doped with nitrogen and gold fine particles are supported using chemical modification in a liquid has been reported (see Non-Patent Document 1). In addition, an example in which a platinum salt solution is impregnated with a cup-stacked carbon nanotube and further reduced in a high-temperature hydrogen atmosphere to support platinum fine particles on the carbon nanotube has been reported (see Non-Patent Document 2). In particular, this report mentions that platinum-supported carbon nanotubes can be used as catalysts for fuel cell electrodes.

  By supporting fine particles on carbon nanotubes in this way, it is expected to make use of the characteristics of carbon nanotubes, add new functions to carbon nanotubes, and use them in various fields including the fuel cell field. Has been.

  In recent years, a material in which a plurality of carbon nanotubes are combined, that is, a so-called carbon nanotube network or a branched carbon nanotube called a carbon nanotube junction has been formed. Such branched carbon nanotubes are expected to further expand the field of use of carbon nanotubes in the future as they use carbon nanotubes that have been treated one-dimensionally in three dimensions (Patent Literature). 1. See Non-Patent Documents 3 and 4.)

In addition to this, for example, a three-dimensional structure of amorphous carbon partially deposited with a catalytic metal such as iron is formed by focused ion beam scanning in a hydrocarbon gas, and this is about 700 ° C. to 900 ° C. A graphite structure having a structure like a branched carbon nanotube obtained by heat treatment has also been proposed (see Patent Document 2).
JP 2004-18328 A JP 2003-238123 A “Nano Letters”, 2003, vol. 3, p. 275 “Nano Letters”, 2003, vol. 3, p. 723 “Applied Physics Letters”, 2001, vol. 79, p. 1879 “Nature”, 1999, vol. 402, p. 253

However, the conventional carbon nanotube formation technology has some problems as described below.
First, with regard to supporting fine particles on carbon nanotubes, for example, in the case of the above-described method of supporting fine gold particles in a liquid after nitrogen doping to carbon nanotubes, the composition of the carbon nanotubes themselves changes due to nitrogen doping. Thus, the carbon nanotube with which composition changed can be used only for a certain specific use. Also, with this method, it is considered that there is a limit to the types of fine particles that can be carried, and problems remain in terms of versatility.

  In the method of impregnating the above-described cup-stacked carbon nanotubes in a platinum salt solution and reducing them to carry platinum fine particles on the carbon nanotubes, the carbon nanotubes are limited to the cup-stacked type. Further, in this method, there is a possibility that substances other than the substance to be precipitated as fine particles may remain on the carbon nanotube.

  Furthermore, since these two methods both use a reaction in a liquid or the like, the carbon nanotubes aggregate together, and as a result, the resulting carbon nanotubes are bundled. It is difficult to separate the bundled carbon nanotubes into independent carbon nanotubes, and coupled with the problems such as the change in the composition of carbon nanotubes and adhesion of impurities described above, its field of use is very limited as it is. It has been done.

  On the other hand, if fine particles are supported on carbon nanotubes in an upright state such as vertically aligned and grown in a specific region on a plane such as a substrate, the application range is wide and can be used in various fields. It is considered. However, until now, there has been no suitable method for supporting fine particles on carbon nanotubes grown on a flat surface.

  There are also several problems with the conventional methods for forming branched carbon nanotubes. For example, conventionally, a method of forming Y junction carbon nanotubes using fine holes of alumina as a template has been proposed. In this method, the structure of the Y junction of carbon nanotubes is determined by the alumina template. ing. However, the controllability of the alumina template is not necessarily good.

  A method has also been proposed in which cobalt is supported on magnesium oxide and Y junction carbon nanotubes are grown therefrom. However, this method makes it difficult to control the number and thickness of the carbon nanotube branches.

  In addition, in the method of forming a graphite structure by heat-treating amorphous carbon on which a catalytic metal is deposited, it is considered useful if only one such structure is formed. For example, this may be applied to the entire substrate surface. When it is desired to form a large number, it takes an enormous amount of time for the formation.

  Thus, regarding the formation of branched carbon nanotubes, there has been no suitable method that can be efficiently formed with good controllability. Similarly, with respect to branched carbon nanotubes standing upright on a flat surface and those on which fine particles are supported, an appropriate method capable of forming them efficiently with good controllability so far There was no.

The present invention has been made in view of the above problems, and an object thereof is to provide a method for producing a carbon nanotube of fine particles in a state of standing upright on the plane are supported.

In the present invention, in order to solve the above problems, a method for producing a particulate carbon nanotubes supported, production of carbon nanotubes, characterized in that the bearing by blowing the carbon nanotubes growing the particles on a plane A method is provided.

  According to such a carbon nanotube manufacturing method, fine particles are sprayed and supported on the carbon nanotubes grown on a flat surface, so that a non-bundled fine particle-supported carbon nanotube is realized, and the composition change of carbon nanotubes and other than fine particles are achieved. It becomes possible to avoid adhesion of impurities.

  In the present invention, fine particles are supported on the surface of carbon nanotubes grown on a flat surface. Thereby, the particulate-supported carbon nanotubes that are not bundled can be stably realized with high quality, and can be used in various fields including electric wiring, sensors, and fuel cells.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, a method for supporting fine particles on carbon nanotubes grown on a plane such as a substrate will be described. Carbon nanotubes can be grown on a flat surface using a known method, for example, by depositing a catalytic metal such as cobalt on the flat surface, and using that as the starting point, the chemical vapor deposition (CVD) method is used to vertically grow carbon. Therefore, the details of the description are omitted here.

FIG. 1 is a schematic diagram of a fine particle carrying device.
A particle carrier 1 shown in FIG. 1 includes a particle generator 2, a particle size selector 3, and a particle carrier 4.

  The fine particle generation unit 2 generates fine particles by, for example, laser ablation using a target. The fine particles generated in the fine particle generation unit 2 are sent to the fine particle size selection unit 3 by an inert carrier gas.

  The fine particle size selector 3 is provided for the purpose of aligning the sizes of the fine particles generated by the fine particle generator 2. For the fine particle size selection unit 3, for example, a differential electrostatic classifier (Differential Mobility Analyzer, DMA) that performs selection based on the electric mobility of the fine particles, an impactor using the inertia of the fine particles, or the like can be used.

  The fine particle support unit 4 includes a fine particle support chamber 6 that accommodates a substrate 5 with carbon nanotubes in which a plurality of carbon nanotubes 5a are vertically aligned and grown on the surface of the substrate 5b, and a nozzle 7 that is disposed to face the substrate 5 with carbon nanotubes. Have. The fine particles selected by the fine particle size selection unit 3 are sprayed toward the carbon nanotube-attached substrate 5 together with the carrier gas via the nozzle 7.

  An exhaust system is connected to the particulate holding chamber 6 so that its internal pressure can be controlled. During the process of supporting the fine particles on the carbon nanotube 5a, the inside of the fine particle support chamber 6 is controlled to a low pressure of, for example, 10 Torr or less. Note that the fine particle generation unit 2, the fine particle size selection unit 3, and the like may be low pressure or normal pressure.

  In the fine particle carrier 1, the fine particle size selection unit 3 is not always necessary. However, in the fine particle carrier 1, since the fine particles blown out from the nozzle 7 are dispersed in the carbon nanotubes 5a by a mechanism corresponding to the inertia as will be described later, in order to control the dispersion state well, the fine particle size The sorting unit 3 is preferably provided.

When carrying fine particles using the fine particle carrying device 1 having the above configuration, the dispersion state of the fine particles on the substrate 5 with carbon nanotubes is controlled by certain parameters.
2 and 3 are explanatory views of the dispersion mechanism of fine particles. FIG. 2 is a diagram schematically showing the gas flow and the movement trajectory of the fine particles in the vicinity of the carbon nanotube when the inertia of the fine particles is small. FIG. It is a figure which shows typically the gas flow and the movement locus | trajectory of microparticles | fine-particles in the carbon nanotube vicinity in case the inertia of this is large.

  The dotted line shown in FIGS. 2 and 3 represents a typical gas flow when sprayed from the nozzle 7 serving as a blowing outlet onto the substrate 5 with carbon nanotubes. Thus, the gas usually flows in a state substantially along the upper ends of the plurality of carbon nanotubes 5a. Moreover, the solid line shown in FIG. 2 and FIG. 3 represents the movement trajectory when the fine particles 8 contained in the gas blown out from the nozzle 7 deviate from the gas flow.

  Here, as shown in FIG. 2, when the inertia of the microparticles 8 is small, the microparticles 8 move almost along the flow when the gas flow curves. Therefore, in the case of such fine particles 8, the carbon nanotubes 5a are only supported by those slightly deviated from the gas flow due to Brownian motion. Therefore, such fine particles 8 are selectively carried on the tip portion of the carbon nanotube 5a.

  On the other hand, as shown in FIG. 3, when the inertia of the microparticles 8 is large, the microparticles 8 deviate from the curved portion when the gas flow curves. Thus, the fine particles 8 deviating from the gas flow enter over a wide area from a shallow part to a deep part of the gap of the carbon nanotubes 5a, and are supported on the exposed carbon nanotubes 5a as a whole. .

  As a parameter representing the magnitude of the inertia of the fine particles, there is a Stokes number Stk represented by the following equation (1) (reference: Hinds, WC, Aerosol Technology, John Wiley & Sons, New York, (1982)). .

Stk = τU / (D _n / 2) (1)
Here, τ is the relaxation time of the fine particles, U is the gas velocity at the outlet, and D _n is the inner diameter of the outlet. The relaxation time τ is expressed by the following equation (2).

τ = ρ _P d _P ² C _C / 18μ (2)
Here, ρ _P is the fine particle density, d _P is the fine particle diameter (average particle diameter), C _C is the Cunningham correction coefficient, and μ is the gas viscosity.

  In general, it is said that if the Stokes number Stk is about 1 or more, the inertia of the fine particles in the system is sufficiently large, and the effect due to the inertia cannot be ignored, but the specific value differs depending on the system. For example, in an impactor that collects fine particles on a substrate using inertia, a result that a Stokes number Stk of about 0.2 is a threshold for collecting fine particles has also been reported (see the above-mentioned reference). ).

  Also in the fine particle carrier 1, the Stokes number Stk is an important parameter. As a result of intensive studies, if the Stokes number Stk is 0.1 or less, the carbon nanotube 5a is mainly supported on the tip portion, and if it is 1 or more, highly dispersed support that penetrates deeper can be realized. I understand. Furthermore, the distance D from the tip of the nozzle 7 at the outlet to the substrate 5b is also an important parameter, but this distance D is preferably within about 10 times the inner diameter of the nozzle 7. However, this is not the case when the Stokes number Stk is very large, for example, 10 or more.

The fine particle carrier 1 can carry fine particles in a high vacuum environment. For example, the fine particle carrier 1 can carry fine particles in a low pressure environment of about 10 Torr and a high vacuum environment of about 10 ⁻⁶ Torr. The parameters will also change depending on the case of performing the above. Under such a high vacuum environment, the concept of Stokes number Stk no longer holds, and instead, the kinetic energy of the fine particles becomes an important parameter.

  The fine particle carrier 1 can adjust the exhaust speed and gas flow rate from the fine particle carrier chamber 6 and can control the Stokes number Stk of the fine particles according to the inner diameter of the nozzle 7. Yes.

FIG. 4 is an example of an electron micrograph of the fine particle-supported carbon nanotube.
The detailed formation conditions of the fine particle-supporting carbon nanotubes shown here will be described later. When fine particles are supported using the fine particle support device 1, fine particles are highly dispersed on the surface of the carbon nanotubes as shown in FIG. It becomes possible to carry.

  As described above, in the fine particle supporting method, a gas containing fine particles is sprayed onto the carbon nanotubes grown on the substrate. Therefore, it is possible to easily support fine particles in a desired dispersed state on carbon nanotubes standing on a flat surface by appropriately setting the type, size, shape of the air outlet, gas blowing conditions, etc. become.

  Furthermore, since the fine particle carrying method described above carries the fine particles by an inert gas and directly adheres to the carbon nanotubes, it is possible to avoid problems such as composition change due to doping of carbon nanotubes and impurity adhesion that easily occurs in liquid phase carrying. Thus, it is possible to form a fine particle-supporting carbon nanotube having a stable overall composition.

  Since the fine particle support device 1 can be adapted to support various types and sizes of fine particles, the fine particle support carbon nanotubes can be applied to various fields. An example of such an application is a sensor using semiconductor fine particles.

FIG. 5 is a schematic diagram of a gas sensor using semiconductor nanoparticle-supporting carbon nanotubes.
In the case of forming the gas sensor 10 using the semiconductor nanotube-supporting carbon nanotubes 11 as shown in FIG. 5, first, the carbon nanotubes 11a are cross-linked and grown between the two electrodes 12a and 12b. The fine particle carrying device 1 is used to carry semiconductor fine particles 11b.

  In the gas sensor 10 having such a configuration, when gas molecules, for example, oxygen molecules 13 are adsorbed on the semiconductor fine particles 11b, electrons move from the semiconductor fine particles 11b to the oxygen molecules 13 and the conductance of the semiconductor nanoparticle-supporting carbon nanotubes 11 changes. To do. Therefore, if a circuit capable of measuring conductance is provided between the electrodes 12a and 12b, the amount of oxygen molecules 13 can be measured.

  Another application example of the fine particle-supported carbon nanotube is, for example, a catalyst for a fuel cell electrode. Currently, the catalyst generally used for fuel cell electrodes is platinum fine particles dispersed in carbon black, but the platinum fine particles may agglomerate at the time of catalyst formation or battery operation. There was a problem that it might not fully demonstrate. In response to such a problem, if the carrier is changed from carbon black to carbon nanotubes, and platinum fine particles are supported in such a high dispersion form as shown in FIG. A high-performance fuel cell electrode catalyst can be realized.

  Further, in the fine particle-supported carbon nanotube formed using the fine particle support device 1, it is possible to grow another carbon nanotube from the supported fine particle as a catalyst to form a branched carbon nanotube. .

FIG. 6 is an example of an electron micrograph of branched carbon nanotubes formed using supported fine particles as a catalyst.
The detailed formation conditions of the branched carbon nanotubes shown here will be described later. The carbon nanotubes shown in FIG. 6 are obtained by supporting iron fine particles on the carbon nanotubes grown on a plane using the fine particle support device 1. A carbon nanotube branch is grown by using a CVD method starting from iron fine particles. At this time, the location, number, and thickness of the carbon nanotube branches can be controlled by the location, number, and size of the supported iron fine particles. Further, the length of the carbon nanotube branch can be controlled by the growth time. Therefore, in this method, it can be said that the controllability in forming branched carbon nanotubes is significantly improved as compared with the conventional method.

  Such branched carbon nanotubes can be used in various applications such as electrical wiring and sensors. In particular, if the sensor is configured by further supporting fine particles on the branched carbon nanotubes, the surface area of the sensing unit increases, so that the detection sensitivity can be further improved.

Hereinafter, a method for forming the fine particle-supported carbon nanotube will be described with a specific example.
FIG. 7 shows an example of the configuration of the particulate carrier.
7 includes a particle generation chamber 22 in which a target 21 is accommodated, and a laser irradiation device 23 that irradiates the target 21 with a laser. The fine particle generation chamber 22 is provided with a mechanism for introducing a helium gas (He) at a predetermined flow rate into the fine particle generation chamber 22, and a supply pipe 25 for sending the introduced helium gas to the DMA 24 together with fine particles generated inside is connected. Yes. An electric furnace 26 is provided on the outer periphery of the supply pipe 25 so that the aggregation of the fine particles sent from the fine particle generation chamber 22 to the DMA 24 in the supply pipe 25 is suppressed.

  The DMA 24 guides the gas containing fine particles sent through the supply pipe 25 to the inside thereof, sorts the size of the fine particles, and sends the gas containing fine particles after sorting to the fine particle carrying chamber 27 side.

Here, FIG. 8 is a schematic sectional view of the DMA.
As shown in FIG. 8, the DMA 24 has a double cylindrical structure of an outer cylinder 24a and an inner cylinder 24b. A sheath gas Qs is flowed in a laminar flow state inside the outer cylinder 24a, and a supply pipe is provided from the outer periphery. Gas Qp containing fine particles is introduced through 25. When a DC voltage is applied between the outer cylinder 24a and the inner cylinder 24b, the fine particles 24c in the gas Qp flow down on the flow of the sheath gas Qs while being attracted to the inner cylinder 24b by the Coulomb force. At this time, the speed at which the fine particles 24c cross the flow of the sheath gas Qs is determined by the balance between the resistance force and the Coulomb force that the fine particles 24c receive from the sheath gas Qs. Since the position at which the fine particles 24c reach the inner cylinder 24b varies depending on the size of the fine particles 24c as described above, a slit 24d is provided in the inner cylinder 24b, and only the fine particles 24c that have reached the inner cylinder 24b are taken out to thereby remove the fine particles 24c of a specific size. Can be sorted out.

  Returning to FIG. 7, the gas containing the sorted fine particles that has passed through the DMA 24 is introduced into the fine particle carrying chamber 27 through the nozzle 28. In the fine particle holding chamber 27, a substrate 30 with carbon nanotubes is arranged on a stage 29 so as to face the nozzle 28, and a gas containing fine particles after selection is sprayed from the nozzle 28 toward the substrate 30 with carbon nanotubes. It is supposed to be. A pump 31 is connected to the particulate holding chamber 27 so that the internal pressure can be controlled.

  Using the particulate carrier 20 having such a configuration, first, a cobalt substrate is arranged as a target 21 in the particulate generation chamber 22 and the internal pressure is controlled to about 10 Torr, and then a pulse laser from the laser irradiation device 23 is applied to the cobalt substrate. Then, a second harmonic of an Nd: YAG laser having a repetition frequency of 20 Hz was irradiated. The cobalt substrate was heated by this laser irradiation to generate vapor. The vapor was cooled by helium gas introduced at a flow rate of about 1 standard liter per minute (slm) into the fine particle generation chamber 22, and cobalt fine particles were generated by nuclear condensation at that time.

  The fine particles generated in this way were sent to the DMA 24 through the supply pipe 25 together with helium gas, and sorted into fine particles having an average particle diameter of about 4 nm. Then, the gas containing fine particles after size selection was guided to the nozzle 28 having an inner diameter of 2 mm, and introduced into the fine particle carrying chamber 27 from there. From the tip of the nozzle 28, the particle holding chamber 27 has a carbon nanotube-attached substrate 30 in which carbon nanotubes 30 a are oriented and grown on the substrate 30 b substantially perpendicular to the axial direction of the nozzle 28 before the introduction of the gas containing the particles. The distance to the substrate 30b was arranged to be about 4 mm, and the internal pressure was controlled to about 10 Torr.

  Under this condition, the Stokes number Stk of the fine particles blown out from the nozzle 28 was about 1.9. The fine particles introduced into the fine particle supporting chamber 27 were supported on the carbon nanotubes 30a almost 100%. The helium gas was exhausted out of the particulate support chamber 27 by the pump 31.

  The fine particle-carrying carbon nanotubes formed at this time are shown in FIG. 4, and fine particles can be carried in a highly dispersed manner on the surface of the independent carbon nanotubes 30a by this fine particle carrying method.

Subsequently, a method for forming a branched carbon nanotube will be described with a specific example.
First, in the same manner as in the above example, iron fine particles having an average particle diameter of about 4 nm were generated and supported in a highly dispersed manner on the surface of carbon nanotubes that were oriented and grown substantially vertically on the substrate.

  Next, the carbon nanotube-carrying substrate carrying the fine particles was transported to the CVD chamber, and carbon was grown by CVD from the carried fine particles. Here, a hot filament CVD method is used, a acetylene / argon mixed gas (1: 9) with a flow rate of about 10 standard cubic centimeters per minute (sccm), a substrate temperature of 670 ° C., a pressure of 100 Pa, and a growth time of 10 minutes. Made growth.

  The branched carbon nanotubes formed at this time are shown in FIG. 6 described above, and with this supporting method, branches of carbon nanotubes could be grown starting from iron fine particles that act as a catalyst. It is also possible to continue to support iron fine particles on the carbon nanotubes formed in this way, and to further grow branches of the carbon nanotubes starting from them.

  Such a method for forming branched carbon nanotubes can grow carbon nanotube branches starting from fine particles, can form a large number of branched carbon nanotubes in a short time, and can be repeatedly formed. It can be said that it has a great advantage over the conventional methods for forming branched carbon nanotubes in that it can suppress the variation of the above.

  In the above description, only one type of fine particles supported on the carbon nanotube is used, but two or more types of fine particles may be used. In the above description, the nozzle is used as the outlet for spraying fine particles on the carbon nanotube. However, a tube, an orifice, or the like can also be used.

(Appendix 1) A carbon nanotube carrying fine particles,
A carbon nanotube which is grown on a flat surface and has the fine particles supported on its surface.

(Supplementary note 2) The carbon nanotube according to supplementary note 1, wherein the fine particles are directly attached to the surface.
(Supplementary note 3) The carbon nanotube according to supplementary note 1, wherein the supported fine particles are two or more kinds.

(Additional remark 4) The said microparticle is a catalyst for carbon nanotube growth, The carbon nanotube of Additional remark 1 characterized by the above-mentioned.
(Supplementary note 5) The carbon nanotube according to supplementary note 1, wherein the fine particle is a catalyst for a fuel cell electrode.

(Supplementary note 6) The carbon nanotube according to supplementary note 1, wherein another carbon nanotube is grown starting from the supported fine particles.
(Appendix 7) A method for producing a carbon nanotube carrying fine particles,
A method of producing a carbon nanotube, comprising spraying and supporting the fine particles on a carbon nanotube grown on a flat surface.

(Additional remark 8) The said microparticles | fine-particles are sprayed on the said carbon nanotube with gas, The manufacturing method of the carbon nanotube of Additional remark 7 characterized by the above-mentioned.
(Additional remark 9) Before spraying on the said carbon nanotube, the manufacturing method of the carbon nanotube of Additional remark 7 characterized by selecting the size of the said fine particle.

  (Additional remark 10) The manufacturing method of the carbon nanotube of Additional remark 7 characterized by the distance from the blowing outlet for spraying the said microparticles | fine-particles to the said carbon nanotube being within 10 times the internal diameter of the said blowing outlet.

  (Additional remark 11) When spraying the said microparticles | fine-particles on the said carbon nanotube, the Stokes number of the said microparticle is controlled, The manufacturing method of the carbon nanotube of Additional remark 7 characterized by the above-mentioned.

  (Supplementary note 12) The carbon nanotube production method according to supplementary note 11, wherein the Stokes number is 0.1 or less when the fine particles are selectively supported on a tip portion of the carbon nanotube.

  (Supplementary note 13) The carbon nanotube production method according to supplementary note 11, wherein the Stokes number is 1 or more when the fine particles are entirely supported on the surface of the carbon nanotube.

(Additional remark 14) The carbon nanotube manufacturing method of Additional remark 7 characterized by growing another carbon nanotube from the carry | supported said microparticles | fine-particles as the starting point.
(Additional remark 15) The manufacturing method of the carbon nanotube of Additional remark 14 characterized by controlling the number and thickness of said another carbon nanotube with the number and magnitude | size of said fine particle.

(Additional remark 16) After making the said another carbon nanotube grow, the new microparticles are sprayed and it supports, The manufacturing method of the carbon nanotube of Additional remark 14 characterized by the above-mentioned.
(Additional remark 17) The carbon nanotube manufacturing method of Additional remark 16 characterized by growing a new carbon nanotube from the carry | supported said microparticles | fine-particles as the starting point.

It is a schematic diagram of a fine particle support device. It is a figure which shows typically the gas flow in the carbon nanotube vicinity in case the inertia of a microparticle is small, and the movement locus | trajectory of a microparticle. It is a figure which shows typically the gas flow and the movement locus | trajectory of microparticles | fine-particles in the carbon nanotube vicinity in case the inertia of microparticles | fine-particles is large. It is an example of the electron micrograph of a fine particle carrying | support carbon nanotube. It is a schematic model diagram of the gas sensor using the semiconductor nanoparticle carrying | support carbon nanotube. It is an example of the electron micrograph of the branched carbon nanotube formed using the carry | supported microparticles | fine-particles as a catalyst. It is an example of composition of a particulate support device. It is the cross-sectional schematic of DMA.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,20 Particulate support device 2 Particulate generation part 3 Particulate size selection part 4 Particulate support part 5,30 Substrate with carbon nanotube 5a, 11a, 30a Carbon nanotube 5b, 30b Substrate 6,27 Particulate support chamber 7, 28 Nozzle 8, 24c Fine particle 10 Gas sensor 11 Semiconductor fine particle supported carbon nanotube 11b Semiconductor fine particle 12a, 12b Electrode 13 Oxygen molecule 21 Target 22 Fine particle generation chamber 23 Laser irradiation apparatus 24 DMA
24a outer cylinder 24b inner cylinder 24d slit 25 supply pipe 26 electric furnace 29 stage 31 pump Qs sheath gas Qp gas

Claims (6)

A method for producing a carbon nanotube carrying fine particles,
A method of producing a carbon nanotube, comprising spraying and supporting the fine particles on a carbon nanotube grown on a flat surface.   The method for producing carbon nanotubes according to claim 1, wherein the fine particles are sprayed onto the carbon nanotubes together with a gas.   The method for producing carbon nanotubes according to claim 1, wherein the size of the fine particles is selected before spraying on the carbon nanotubes.   When spraying and supporting the fine particles together with the gas on the carbon nanotubes, the density of the fine particles used for determining the Stokes number of the fine particles to be sprayed based on the region of the carbon nanotubes supporting the fine particles, 3. The method for producing carbon nanotubes according to claim 2, wherein an average particle diameter, a viscosity of the gas to be used, a speed at the gas outlet, and an inner diameter of the outlet are set.   The method for producing carbon nanotubes according to claim 1, wherein another carbon nanotube is grown from the supported fine particles as a starting point.   When spraying and supporting the fine particles on the carbon nanotubes, the fine particles having a number and size set based on the number and size of the other carbon nanotubes to be grown are sprayed and supported. 6. The method of producing a carbon nanotube according to claim 5, wherein the another carbon nanotube is grown at a starting point.

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