JP6847412B2 - Catalytic base material for manufacturing carbon nanotube aggregates and method for manufacturing carbon nanotube aggregates - Google Patents

Description

The present invention relates to a method for producing an aggregate of carbon nanotubes. In particular, the present invention relates to a method for producing a carbon nanotube aggregate using a method of adjusting metal catalyst fine particles exhibiting high activity at a high density on a substrate in a short time and efficiently.

Recently, it is expected that carbon nanotubes (hereinafter, also referred to as CNTs) will be used in new functional materials such as electronic device materials, optical element materials, conductive materials, and biological materials. Studies on mass productivity are being energetically promoted.

A chemical vapor deposition method (hereinafter, also referred to as a CVD method) is known as one of the methods for producing CNTs (see Patent Document 1 and the like). This method is characterized in that a raw material gas such as a carbon compound is brought into contact with the catalyst fine particles in a high temperature atmosphere of about 500 ° C. or higher and 1200 ° C. or lower, and the type and arrangement of the catalyst, the type of raw material gas, and the reducing gas. It is possible to produce CNTs in various modes such as atmospheric gas, synthesis furnace and reaction conditions, and it is attracting attention as being suitable for mass production of CNTs. In addition, this CVD method can produce both single-walled CNTs and multi-walled CNTs, and by using a base material carrying a catalyst, a CNT aggregate in which a large number of CNTs are vertically oriented on the base material surface can be manufactured. It has the advantage of being able to.

Among CNTs, single-layer CNTs have electrical characteristics (extremely high current density), thermal characteristics (thermal conductivity comparable to diamonds), optical characteristics (emission in the optical communication band wavelength range), hydrogen storage capacity, and In addition to being excellent in various properties such as metal catalyst carrying capacity, it has both semiconductor and metal properties, so it is attracting attention as a material for electronic devices, electrodes for power storage devices, MEMS members, and fillers for functional composite materials. Has been done.

Further, a vertically oriented CNT aggregate having few metal impurities and ^{a high specific surface area of 800 m 2} / g or more is effective as a catalyst carrier and an energy / material storage material, and is suitable for applications such as supercapacitors and actuators. Is.

If such vertically oriented CNT aggregates are created, it is predicted that the application fields of CNTs will expand dramatically, but in order to promote practical use, mass productivity of vertically oriented CNT aggregates is expected. It is important to improve.

Japanese Unexamined Patent Publication No. 2003-171108 Japanese Unexamined Patent Publication No. 2010-248073

Shunsuke Sakurai et al, “Role of Subsurface Diffusion and Ostwald Ripening in Catalyst Formation for Single-Walled Carbon Nanotube Forest Growth” J. Am. Chem. Soc. 2012, 134, 2148-2153 Wen-I Liang et al, “In Situ Study of Fe3Pt-Fe2O3 Core-Shell Nanoparticle Formation” J. Am. Chem. Soc. 2015, 137, 14850? 14853 D. N. Futaba et al, “84% Catalyst Activity of Water-Assisted Growth of Single Walled Carbon Nanotube Forest characterization by a Statistical and Macroscopic Approach”, J. Phys. Chem. B, 2006, 110 (15), pp 8035-8038

In the CVD method, in order to synthesize CNT aggregates, particularly single-walled CNT aggregates with high efficiency, it is necessary to arrange fine and highly active catalyst fine particles at high density on the substrate. In the conventional chemical vapor deposition method such as Patent Document 2, in order to prepare the catalyst fine particles, the following steps called formation steps are required. That is, the reducing gas is supplied from the outside of the CNT manufacturing apparatus, brought into contact with the catalytic substance on the base material arranged in the CNT manufacturing apparatus, and at least one of the catalytic substance and the reducing gas is heated to heat the catalytic substance. The step of reducing and / or atomizing the gas was essential. After this formation step, a CNT aggregate can be produced by a CNT growth step in which a raw material gas diluted with an inert gas is brought into contact with the catalyst fine particles.

However, this formation process has the following problems. First, in a state where a large amount of reducing gas supplied in the formation step remains around the base material, decomposition of the raw material gas (hydrocarbon) supplied in the manufacturing apparatus is suppressed in the subsequent CNT growth step, and CNTs are suppressed. Growth efficiency will decrease. In order to quickly remove residual hydrogen from around the substrate, the reducing gas is discharged from the manufacturing apparatus at high speed, or the CNT growth step is performed from the chamber in an atmosphere suitable for the formation step (as in Patent Document 2). It is necessary to transport the base material to a chamber having an atmosphere suitable for the above, but in each case, a certain amount of time is required and the manufacturing efficiency is lowered. Secondly, many reducing gases are flammable and toxic, and since a large amount of such gases are used, this process is problematic in terms of cost and safety.

However, in the prior art, catalyst fine particles exhibiting high activity are arranged at high density on the base material without using a reducing gas, for example, by simply heating the catalyst substance on the base material in an inert gas atmosphere. It was known that carbon nanotubes could not be synthesized even in the subsequent CNT synthesis step (Non-Patent Document 1).

The present invention solves the above-mentioned problems of the prior art, and provides a method for producing carbon nanotubes with high efficiency even if the conventional formation step is omitted.

According to one embodiment of the present invention, the base material, the catalyst metal element provided on the base material, the co-catalyst metal element having an electron affinity of 50 kJ / mol or more, and the catalyst metal element when heated. Alternatively, a carbon nanotube aggregate comprising a catalyst precursor layer containing an alloying auxiliary substance that prevents the co-catalyst metal element from aggregating and promotes mixing of the catalyst metal element with the co-catalyst metal element. A catalyst substrate for production is provided.

In the catalyst base material for producing an aggregate of carbon nanotubes, the alloying auxiliary substance may be a high molecular weight organic compound or a low molecular weight organic compound having two or more sites that coordinate with the catalyst metal element.

In the catalyst base material for producing carbon nanotube aggregates, the alloying auxiliary substances include polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone and derivatives thereof, as well as ethylenediamine, bipyridine, citric acid, ethylenediaminetetraacetic acid, phenanthroline, crown ether and porphyrin. , And derivatives thereof, may be one or more selected from the group.

In the catalyst base material for producing carbon nanotube aggregates, the alloying auxiliary substance may be present in an amount of 2% by weight or more in the catalyst precursor layer.

In the catalyst base material for producing carbon nanotube aggregates, when the number of elements contained in the catalyst metal element is M and the number of elements contained in the co-catalyst metal element is N in the catalyst precursor layer, N / M is It may be 0.01 or more and 2 or less.

In the catalyst base material for producing an aggregate of carbon nanotubes, a base layer containing a metal oxide may be provided on the surface of the base material.

Further, according to one embodiment of the present invention, the catalyst metal element and the co-catalyst metal element are produced by producing any of the catalyst base materials for producing an aggregate of carbon nanotubes and heating the catalyst precursor layer. Provided is a method for producing a carbon nanotube aggregate, which comprises forming the contained metal catalyst fine particles on a substrate and bringing a hydrocarbon gas into contact with the metal catalyst fine particles to grow the carbon nanotube aggregate.

In the method for producing an aggregate of carbon nanotubes, a solution prepared by dissolving the metal compound containing the catalyst metal element, the metal compound containing the co-catalyst metal element, and the alloying auxiliary substance is applied onto a substrate. Then, the catalyst base material for producing the carbon nanotube aggregate may be produced by drying.

In the method for producing an aggregate of carbon nanotubes, by heating the catalyst precursor layer, the alloying auxiliary substance is thermally decomposed to generate a reducing gas, and the reducing gas reduces the catalyst metal element. , The catalyst metal element and the co-catalyst metal element may be alloyed and made into fine particles to form the metal catalyst fine particles.

In the method for producing an aggregate of carbon nanotubes, the metal catalyst fine particles having a particle size in the range of 1 nm or more and 10 nm or less may be formed on the base material at a number density of ^{1 × 10 10} particles / cm ^{2 or more.}

In the method for producing the carbon nanotube aggregate, the carbon nanotube aggregate may be grown from the surface of the base material at a yield of ^{0.1 mg / cm 2 or more.}

According to one embodiment of the present invention, in a chemical vapor deposition method in which a raw material gas and a catalyst activator are brought into contact with a catalyst to grow CNT aggregates in a furnace at a high temperature, the amount is high in a short time and efficiently. Since the metal catalyst fine particles exhibiting the activity can be prepared at a high density on the substrate, the carbon nanotube aggregate can be produced more efficiently than before.

It is a schematic diagram which shows the manufacturing method of the catalyst base material for manufacturing of CNT aggregate and the manufacturing method of CNT aggregate which concerns on one Embodiment of this invention. It is a schematic diagram of the manufacturing apparatus 100 of the CNT aggregate which concerns on one Embodiment of this invention. (A) is an AFM image of the metal catalyst fine particles formed on the catalyst base material for producing the CNT aggregate according to the embodiment of the present invention, and (B) is the Raman of the CNT aggregate according to the embodiment of the present invention. It is a spectrum. (A) is an AFM image of the metal catalyst fine particles formed on the catalyst base material for producing the CNT aggregate according to the embodiment of the present invention, and (B) is the Raman of the CNT aggregate according to the embodiment of the present invention. It is a spectrum. (A) is an AFM image of the metal catalyst fine particles formed on the catalyst base material for producing the CNT aggregate according to the embodiment of the present invention, and (B) is the Raman of the CNT aggregate according to the embodiment of the present invention. It is a spectrum. (A) is an AFM image of the metal catalyst fine particles formed on the catalyst base material for producing the CNT aggregate according to the embodiment of the present invention, and (B) is the Raman of the CNT aggregate according to the embodiment of the present invention. It is a spectrum. (A) is an AFM image of the metal catalyst fine particles formed on the catalyst base material for producing the CNT aggregate according to the embodiment of the present invention, and (B) is the Raman of the CNT aggregate according to the embodiment of the present invention. It is a spectrum. It is an SEM image of the CNT aggregate which concerns on one Example of this invention. (A) is an AFM image of the metal catalyst fine particles formed on the catalyst base material for producing the CNT aggregate according to the embodiment of the present invention, and (B) is the Raman of the CNT aggregate according to the embodiment of the present invention. It is a spectrum. (A) is an AFM image of the metal catalyst fine particles formed on the catalyst base material for producing the CNT aggregate of the comparative example, and (B) is the Raman spectrum of the CNT aggregate of the comparative example. (A) is an AFM image of the metal catalyst fine particles formed on the catalyst base material for producing the CNT aggregate of the comparative example, and (B) is the Raman spectrum of the CNT aggregate of the comparative example. (A) is an AFM image of the metal catalyst fine particles formed on the catalyst base material for producing the CNT aggregate of the comparative example, and (B) is the Raman spectrum of the CNT aggregate of the comparative example. (A) is an AFM image of the metal catalyst fine particles formed on the catalyst base material for producing the CNT aggregate of the reference example, and (B) is the Raman spectrum of the CNT aggregate of the reference example.

Hereinafter, the catalyst base material for producing the carbon nanotube aggregate and the method for producing the carbon nanotube aggregate according to the present invention will be described with reference to the drawings. The catalyst base material for producing carbon nanotube aggregates and the method for producing carbon nanotube aggregates of the present invention are not construed as being limited to the contents of the embodiments and examples shown below. In the drawings referred to in the present embodiment and the examples described later, the same parts or parts having the same functions are designated by the same reference numerals, and the repeated description thereof will be omitted.

The present inventors have formed a catalyst precursor layer in which a compound containing a catalyst metal element, which is a transition metal element, and a compound containing a co-catalyst metal element having a high electron affinity are mixed at the molecular level. It has been found that by heating the above, metal catalyst fine particles having a particle size and a high density suitable for producing CNT can be formed regardless of the atmosphere at the time of heating.

<Catalyst metal element>
As the catalyst metal element, one or more kinds often used as a catalyst for synthesizing CNT aggregates can be selected from the Group VIIIB transition metal. In particular, one or more selected from the group consisting of iron, cobalt and nickel, which are often used as catalysts for synthesizing CNT aggregates, are desirable.

<Cocatalyst metal element>
It is desirable that the co-catalyst metal element has a high electron affinity. In one embodiment, the cocatalyst metal element has an electron affinity of 50 kJ / mol or more, preferably 100 kJ / mol or more. In general, metal elements having high electron affinity, such as precious metal elements, are metals regardless of their atmosphere when heated to a high temperature, even if they are various metal compounds in a positively charged state. It is disassembled into a single unit. For example, platinum (II) chloride (PtCl ₂ ) decomposes into platinum and chlorine when heated in air. That is, a chemical reaction of _{PtCl 2} → Pt + Cl _{2 occurs.} The co-catalyst metal element in the metallic state thus generated assists the reduction of the co-catalyst metal element in the oxidized state when contact-mixed with the catalytic metal element in the oxidized state, and as a result, an alloy composed of the catalytic metal element and the co-catalyst metal element. Has the function of forming. For example, according to Non-Patent Document 2, an iron-platinum alloy phase is formed by thermally decomposing a mixed aqueous solution of platinum chloride and iron chloride under anaerobic conditions.

In particular, the co-catalyst metal element is preferably an element having a wide composition ratio capable of forming an alloy with iron, cobalt or nickel, which are generally used as catalysts for CNT. For example, the noble metal elements platinum, rhodium, iridium, and palladium form a complete solid solution with iron.

Further, since the catalyst for CNT production is used at a relatively high temperature, it is desirable that the element has a high melting point. In one embodiment, the co-catalyst metal element has a melting point of 1000 ° C. or higher, preferably 1500 ° C. or higher. It is preferably 1800 ° C. or higher, and more preferably 2000 ° C. or higher.

From this point of view, the co-catalyst metal element is a group of elements in which the noble metal element is desirable as the co-catalyst metal element. In one embodiment, the cocatalyst metal elements are gold (Au, 223 kJ / mol, melting point: 1064 ° C.), silver (Ag, electron affinity: 126 kJ / mol, melting point: 961 ° C.),), platinum (Pt, electron affinity). : 205 kJ / mol, melting point: 1769 ° C.), palladium (Pd, electron affinity: 54 kJ / mol, melting point: 1552 ° C.), rhodium (Rh, electron affinity: 110 kJ / mol, melting point: 1960 ° C.), iridium (Ir, electron Select from the group consisting of affinity: 150 kJ / mol, melting point: 2443 ° C.), ruthenium (Ru, electron affinity: 101 kJ / mol, melting point: 2250 ° C.), osmium (Os, electron affinity: 104 kJ / mol, melting point: 3045 ° C.). It is desirable to be done. However, since silver does not form an alloy with iron, when iron is selected as the catalyst metal element, the co-catalyst metal element is selected from the above noble metals other than silver. Further, in one different embodiment, the cocatalyst metal element is chromium (Cr, electron affinity: 64 kJ / mol, melting point: 1857 ° C.), copper (Cu, electron affinity: 119 kJ / mol, melting point: 1085 ° C.). Is also good. Further, in one embodiment, the co-catalyst metal element may be one or more combinations selected from the above noble metals and the like. The co-catalyst metal element according to the present invention does not include tungsten or molybdenum used as a general co-catalyst.

In the present invention, such characteristics of the co-catalyst metal element are utilized to form a catalyst precursor layer in which the catalyst metal element and the co-catalyst metal element are mixed at the molecular level. In one embodiment, the catalyst precursor layer has an effect of stabilizing the reduced metal state of the catalyst metal element by the co-catalyst metal element having high electron affinity without using a reducing gas. As a result, a catalyst metal-auxiliary catalyst metal alloy is produced, and the alloy is made into fine particles on the base material, so that metal catalyst fine particles suitable for producing CNT can be formed.

As a means for forming a catalyst precursor layer in which a catalyst metal element and a co-catalyst metal element are mixed at the molecular level, an alloying auxiliary substance having a role of maintaining a mixed state of both elements in the catalyst precursor layer is used as a catalyst. The method of mixing in the precursor layer is effective. This makes it possible to prevent the catalyst metal element or the co-catalyst metal element from aggregating as a single particle in the process of raising the temperature of the catalyst precursor layer to a temperature suitable for forming the alloy.

In the catalyst precursor layer, the content of the co-catalyst metal element with respect to the catalyst metal element is not particularly limited. However, if the content of the co-catalyst metal element is too small, the effect of promoting the reduction and fine particle formation of the catalytic metal element is not exhibited. Further, if the content of the co-catalyst metal element is too large, the catalyst metal element is diluted too much, and the metal catalyst fine particles cannot exhibit sufficient CNT growth activity. Therefore, the ratio of the number of co-catalyst metal elements / the number of catalytic metal elements is 0.01 or more and 2 or less, preferably 0.01 or more and 0.8 or less, and more preferably 0.01 or more and 0.5 or less.

<Catalyst raw material>
As the catalyst metal element and the co-catalyst metal element, not only a simple substance of a metal composed of only the metal element but also a metal compound can be used as a catalyst raw material. In one embodiment, the catalyst raw material may be present in a form containing a metal salt such as chloride, an oxide, a nitride, a sulfide, or an organometallic compound such as an acetylacetate complex. Further, as long as it is a trace amount, a metal element other than the element constituting the catalyst metal may be mixed.

<Alloying auxiliary material>
The alloying auxiliary material has a single catalytic metal element or auxiliary catalyst metal element until the alloying auxiliary material itself thermally decomposes when the temperature of the catalyst precursor layer is raised to a temperature suitable for forming an alloy. It is desirable to have a function of suppressing aggregation as particles. As the substance having such a function, it is desirable that it is a high molecular weight organic compound or a low molecular weight organic compound having two or more coordination sites capable of coordinating with the catalytic metal element. Specific examples of the alloying auxiliary substance include organic compounds having two or more functional groups that function as coordination sites, such as alcoholic hydroxyl groups, carbonyl groups, and ether groups. More specifically, polymer organic compounds selected from the group consisting of polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone and derivatives thereof, and polydentate ligands ethylenediamine, bipyridine, citric acid, ethylenediamine tetraacetic acid, and phenanthroline. , Crown ethers, porphyrins, and low molecular weight organic compounds selected from the group consisting of derivatives thereof.

The thermal decomposition temperature of the alloying auxiliary substance is not particularly limited, but is preferably in the range of 300 ° C. or higher and 900 ° C. or lower. Since alloying does not proceed at 300 ° C. or lower, after the alloying auxiliary substance is thermally decomposed, the catalyst metal element or the co-catalyst metal element tends to aggregate as a single particle. On the other hand, at 900 ° C. or higher, most of the metal catalyst fine particles prepared on the substrate after the alloying auxiliary substance is decomposed disappear at high speed due to a phenomenon such as Ostwald ripening, and a high number density suitable for CNT synthesis is obtained. It is not suitable for the preparation of metal catalyst fine particles.

The alloying auxiliary substance is preferably a substance that generates a reducing gas during thermal decomposition. The reducing gas generated in the catalyst precursor layer can immediately come into contact with the catalyst raw material in the catalyst precursor layer, and reduces and / or reduces the catalyst metal element and the co-catalyst metal element contained in the catalyst raw material. It can be made into fine particles. The reducing gas includes, for example, hydrogen, carbon monoxide, ammonia, nitrous oxide oxygen (N 2 _O), a reducing effect on sulfur dioxide (SO ₂₎ catalytic metal element and / or promoter metal element such as It is a substance. For example, any organic compound containing a hydrogen atom that generates hydrogen gas during thermal decomposition can be used as an alloying auxiliary substance.

The content of the alloying auxiliary substance with respect to the catalyst raw material in the catalyst precursor layer is not particularly limited because it is not necessary to coordinate all the metal elements contained in the catalyst raw material. However, since it is easy to prevent the agglomeration of the catalyst metal element and the co-catalyst metal element in a certain amount, 2% by weight or more, preferably 5% by weight or more, and more preferably 50% by weight in the catalyst precursor layer. The above is included.

<Catalyst precursor layer>
The thickness of the catalyst precursor layer is not particularly limited as long as a catalyst precursor layer sufficient for producing the CNT aggregate can be obtained. Further, the thickness of the entire catalyst precursor layer is not particularly limited, and it is not necessary to cover the entire base material. However, typically, since the total volume of the metal catalyst fine particles obtained after the catalyst precursor layer is thermally decomposed is the thickness of the catalyst precursor layer corresponding to the volume of the alloy film of about 1 nm, the thickness of the catalyst precursor layer is set after the film formation. The catalyst precursor layer is 10 nm or more, preferably 100 nm or more.

The mixed state of the catalyst raw material and the alloying auxiliary material in the catalyst precursor layer is not limited. That is, the catalyst raw material may be present separately from the alloying auxiliary substance in the form of fine particles or a film. However, in order to further promote alloying, it is desirable that the substances constituting the catalyst precursor layer are mixed at the molecular level by coordinating the metal elements constituting the catalyst raw material to the alloying auxiliary substance.

<Base material>
The base material is a member capable of supporting a catalyst for growing CNTs on its surface, and an appropriate base material can be used as long as it can maintain its shape even at a high temperature of at least 400 ° C. or higher. As the form of the base material, a flat form such as a flat plate is preferable for producing a large amount of CNTs by using the effect of the present invention. However, it may be a base material having a flat surface, which is a powder or an aggregate of linear bodies. It is preferable to use a flat base material because it is easy to uniformly supply the raw material gas and the catalyst activator to the catalyst.

Materials that have been proven in the production of CNTs include iron, nickel, chromium, molybdenum, tungsten, titanium, aluminum, manganese, cobalt, copper, silver, gold, platinum, niobium, tantalum, lead, zinc, gallium, etc. Metals such as indium, germanium, arsenic, phosphorus, antimony, and alloys and oxides containing these metals, or silicon, quartz, magnesia, spinel, calcia, dolomite, chromia, zirconia, titania, murai, glass, mica, graphite. , Alumina, magnesium oxide, potassium titanate, dilyconium oxide, zeolite, silica, titanium oxide, non-metals such as diamond, ceramics and mixtures thereof. The metal is preferably cheaper than silicon or ceramic, and in particular, iron-chromium (Fe-Cr) alloy, iron-nickel (Fe-Ni) alloy, and iron-chromium-nickel (Fe-Cr-). Ni) alloys and the like are suitable for carrying out the present invention.

Specific examples of the powder or the linear body include plate-like alumina, quartz flakes, quartz fibers, ceramic fibers, and fibrous titanium oxide.

<Underground layer>
An underlayer containing a metal oxide may be provided on the surface of the base material. The base layer is a layer arranged on the surface of the base material as a base of the catalyst layer. The base layer can be formed by forming a known metal oxide on the surface of the base material. Alumina and MgO, which have a proven track record in the growth of long single-walled CNTs, are particularly suitable, but are not limited thereto.

<Catalyst precursor layer film formation process>
The catalyst precursor layer film forming step will be described with reference to FIG. The base layer 102 is formed on the surface of the base material 101 (FIG. 1 (A)). The base layer 102 can be formed by, for example, a sputtering method. A catalyst precursor layer 106 is formed on the surface (or upper surface) of the base layer 102 (FIG. 1 (B)). The film forming process of the catalyst precursor layer 106 is not particularly limited. It may be selected in a timely manner depending on the combination of the selected catalyst raw material and alloying auxiliary material such as the coating method and the vapor deposition method. However, in the catalyst precursor layer to be formed, it is desirable that the alloying auxiliary substance and the catalyst raw material are mixed at the molecular level. Therefore, the film forming step of the catalyst precursor layer 106 includes a step of applying a solution in which at least a part of the catalyst raw material and the alloying auxiliary substance are dissolved on the base material, and a step of drying the base material. Is desirable.

In the film forming step of the catalyst precursor layer 106 described above, the solvent of the solution is not limited, but it is desirable to select a solvent having high solubility of the catalyst raw material and the alloying auxiliary substance. For example, you can choose water or alcohol.

It is desirable that the catalyst raw material and the alloying auxiliary substance dissolved in the solution do not separate or aggregate in the stored solution and in the drying step after the coating step. Therefore, it is desirable that the alloying auxiliary substance is coordinate-bonded to the ionically dissolved catalytic metal element and the auxiliary catalytic metal element in the solution. As a result, contact between the metal elements is suppressed, and aggregation of the catalyst metal element and the co-catalyst metal element in the stored solution and in the drying step after the coating step is suppressed.

The coating method does not matter, but in addition to spin coating, dip coating, spray coating, and blade coating, various coating techniques and printing techniques are applicable. The conditions in the drying step are not particularly limited, but it is desirable that the drying temperature is equal to or lower than the temperature at which decomposition or reaction of the alloying auxiliary substance occurs. For example, it may be dried at room temperature in a vacuum or in the atmosphere, and at that time, the solvent of the solution may remain undried.

<Metal catalyst fine particle forming process>
The catalyst precursor layer 106 is heated to form metal catalyst fine particles 107 (FIG. 1 (C)). After the catalyst precursor layer 106 is heated and the alloying auxiliary substance is thermally decomposed, the catalytic metal element coordinated with the alloying auxiliary substance and the auxiliary catalyst metal element come into immediate contact with each other. At the same time as heating the catalyst precursor layer 106, the thermal decomposition of the compound composed of the co-catalyst metal element which is the catalyst raw material also proceeds, and the co-catalyst metal element alone reduced to the metallic state is also produced. When the catalytic metal element comes into contact with the co-catalytic metal element, the mixing of the two proceeds. By alloying with the co-catalyst metal element, the reduction of the catalyst metal element also proceeds, and the formation of the metal catalyst fine particles 107 on the base material 101 proceeds.

In the present invention, the atmosphere during heating may be any of a reducing gas, an inert gas, and an oxidizing gas. In this step, a catalyst activator may be added if necessary. The reducing gas, such as hydrogen, ammonia, carbon monoxide, nitrous oxide oxygen _(N 2 O), a sulfur dioxide (SO ₂₎ and a mixed gas thereof. Examples of the inert gas include helium, argon, nitrogen, neon, krypton and the like, and a mixed gas thereof, and nitrogen, helium, argon, and a mixed gas thereof are particularly preferable. Oxidizing gas is oxygen, dry air, water vapor and the like.

The metal catalyst fine particle formation temperature is not particularly limited and may be different from the CNT growth step. However, it is desirable that the temperature is equal to or higher than the thermal decomposition start temperature of the alloying auxiliary material used. If the temperature is too low, the catalytic metal element and the co-catalytic metal element cannot come into contact with each other, and alloying does not proceed.

The heating time of the catalyst precursor layer 106 is not particularly limited, but it is necessary to sufficiently start the decomposition of the alloying auxiliary substance. It depends on the alloying aid, its amount, and the decomposition temperature, but is typically preferably 1 second or longer.

By selecting the appropriate amount and mixing state of the catalyst raw material and alloying auxiliary material, and the heating temperature and time, the particle size and number suitable for growing the CNT aggregate oriented in the direction orthogonal to the substrate. Metal catalyst fine particles 107 having a density can be formed on the base material 101.

Specifically, it is desirable that the particle size of the generated metal catalyst fine particles 107 is in the range of 1 nm or more and 10 nm or less, respectively. More preferably, it is in the range of 1 nm or more and 5 nm or less. The number density of the metal catalyst fine particles 107 is ^{preferably 1 × 10 10} particles / cm ² or more, more preferably 3 × 10 ¹⁰ particles / cm ² or more, and further preferably 1 × 10 ¹¹ particles / cm ² or more. As a method for measuring the number density of the metal catalyst fine particles, for example, the base material can be taken out from the CNT manufacturing apparatus after the metal catalyst fine particle forming step, and the surface of the base material can be directly measured with an atomic force microscope (AFM). Alternatively, the number density of CNTs is obtained from the diameter of the CNTs 109 grown in the next CNT growth step, the density of the CNT aggregates, the diameter of the CNTs 109, and the number of layers as follows, and it is estimated that this is equivalent to the number density of the catalysts. can do. That is, the number density of CNTs is (weight density of CNT aggregates) / (linear density of CNTs), but the weight density of CNT aggregates is calculated by measuring the weight and height of CNT aggregates. The CNT linear density can be calculated from the proportional relationship with the diameter of the CNT described in Non-Patent Document 3. The diameter of the CNT 109 can be measured by direct observation by TEM or by the absorption band energy in the absorption spectrum.

<CNT growth process>
Next, by contacting the base material 101 with a mixed gas containing a raw material gas (for example, a hydrocarbon gas such as butane or acetylene), the CNT aggregate 109 is produced from the metal catalyst fine particles 107 at high speed, with high yield, and efficiently. (Fig. 1 (D)). The mixed gas may contain an atmospheric gas and a catalyst activator (for example, water).

<Manufacturing equipment>
The apparatus used for the metal catalyst fine particle forming step and the CNT growth step described above is not particularly limited, and a known apparatus can be used. Further, since the metal catalyst fine particle forming step and the CNT growth step can be performed at the same temperature and the same carrier gas, it is not necessary to separate the chambers used for the two steps. Further, since the temperature and the gas flow rate can be adjusted in a timely manner in each step, the chamber may be separated into the metal catalyst fine particle forming step and the CNT growth step. For example, a general-purpose electric furnace for heating in the atmosphere may be used for the metal catalyst fine particle forming step, and another device may be used for the CNT growth step.

An example of the manufacturing apparatus is shown in FIG. FIG. 2 is a schematic view of a CNT assembly manufacturing apparatus 100 according to an embodiment of the present invention described in Japanese Patent Application No. 2010-279725. The manufacturing apparatus 100 includes, for example, a synthesis furnace 110 in which a base material 101 (for example, a silicon wafer) on which a catalyst precursor layer 106 is previously formed is placed on a base material holder 105. In the synthesis furnace 110, the first gas flow path 145 and the second gas flow path 147 are arranged, and the base material 101 is arranged so as to intersect the surface of the catalyst precursor layer 106 generally perpendicularly. A raw material gas cylinder 161, an atmosphere gas cylinder 163, and a reducing gas cylinder 165 are connected to the first gas flow path 145 via a first gas supply pipe 141. Further, the catalyst activator cylinder 167 is connected to the second gas flow path 147 via the second gas supply pipe 143. A first carbon concentration adjusting means 171 is provided in the first gas supply pipe 141 to adjust the carbon concentration of the first gas supplied from the raw material gas cylinder 161, the atmospheric gas cylinder 163, and the reduced gas cylinder 165. Further, a second carbon concentration adjusting means 173 is provided in the second gas supply pipe 143 to adjust the carbon concentration of the second gas supplied from the catalyst activator cylinder 167.

The synthesis furnace 110 is provided with a gas discharge pipe 150 for discharging the gas supplied from the first gas flow path 145 and the second gas flow path 147 to the outside. Further, the heating means 130 is arranged in the synthesis furnace 110. The first carbon concentration adjusting means 171 and the second carbon concentration adjusting means 173 and the heating means 130 can be controlled by a control means (not shown).

<CNT assembly manufacturing process>
Explaining with reference to FIG. 2, the base material 101 on which the catalyst precursor layer 106 is formed is placed on the base material holder 105, and in the synthesis furnace 110, the first gas supply pipe 141 to the first gas flow path Atmospheric gas (eg, helium) supplied via 145 is filled. The base material 101 is arranged so that the surface of the catalyst precursor layer 106 and the first gas flow path 145 and the second gas flow path 147 intersect with each other generally vertically so that the raw material gas is efficiently supplied to the catalyst.

When the above-mentioned metal catalyst fine particles 107 are formed at this stage, the inside of the synthesis furnace 110 is heated to a predetermined temperature (for example, 750 ° C.), and the state is maintained for a desired time. At least one of the catalyst precursor layer 106 and the atmospheric gas is heated to reduce and / or atomize the catalyst metal element and the co-catalyst metal element. At this time, the atmospheric gas may be supplied into the synthesis furnace 110 from the first gas supply pipe 141 via the first gas flow path 145.

By this heating, the catalyst precursor layer 106 is reduced to metal catalyst fine particles 107 having various particle sizes, which are adjusted to a state suitable as a catalyst for CNT 109. Further, if necessary, a second gas containing a catalyst activator may be added from the second gas supply pipe 143 via the second gas flow path 147. By this step, at least one effect of reducing the catalytic metal element, promoting the atomization of the metal containing the catalytic metal element in a state suitable for the growth of CNT, and improving the activity of the catalytic metal element appears. Next, the supply of atmospheric gas from the first gas flow path 145 is stopped or reduced as desired (reaction conditions).

Subsequently, each of the raw material gas and the catalyst activator is supplied to the gas mixing region 180 in the vicinity of the catalyst layer 103 made of the metal catalyst fine particles 107 from different pipes arranged in the synthesis furnace 110. That is, the raw material gas (for example, butane or propane) and the first gas containing the atmospheric gas are supplied from the first gas supply pipe 141 into the synthesis furnace 110 via the first gas flow path 145, and the catalyst activator (for example). The second gas containing water) is supplied from the second gas supply pipe 143 into the synthesis furnace 110 via the second gas flow path 147. These gases supplied from the first gas flow path 145 and the second gas flow path 147 form a gas flow oriented in a direction substantially parallel to the surface of the catalyst layer 103 of the base material 101, and then the catalyst layer 103. It is mixed in the nearby gas mixing region 180 and supplied in a predetermined amount to the surface of the catalyst layer 103 on the base material 101.

After the production of CNTs is completed, the raw material gas contained in the first gas, the catalyst activator contained in the second gas, their decomposition products, the carbon impurities existing in the synthesis furnace 110, etc., which remain in the synthesis furnace 110, are present. Only the atmospheric gas is flowed from the first gas flow path 145 in order to suppress the adhesion to the CNT aggregate.

The CNT aggregate, catalyst, and substrate 101 are cooled to preferably 400 ° C. or lower, more preferably 200 ° C. or lower in a cooling gas environment. As the cooling gas, an inert gas supplied from the second gas supply pipe 143 is preferable, and nitrogen is particularly preferable from the viewpoint of safety, economy, purging property and the like. In this way, the CNT 109 used for the CNT composite material can be manufactured.

<CNT aggregate>
The manufactured CNT 109 is a vertically oriented body. The length of the CNT 109 is 10 μm or more. It is more preferably 100 μm or more, and more preferably 300 μm or more. The number of layers of CNT109 is not limited, but it is desirable that a single layer is contained in an amount of 10% or more, and more preferably 50% or more is contained.

(Example 1)
As Example 1, iron was used as the catalyst metal element, iridium was used as the co-catalyst metal element, and citric acid and polyvinyl alcohol (PVA) were used as alloying auxiliary substances to prepare a catalyst base material for producing a CNT aggregate. .. First, a silicon wafer (length 40 mm × width 40 mm) was prepared as a base material, and a silicon oxide (SiO ₂ ) film of 500 nm was formed on the surface of the silicon wafer. _{Alumina was deposited on the SiO 2} film on the surface of the base material on which the catalyst was placed by a sputtering method to form a base layer having a diameter of 40 nm or more. The base material on which the base layer was formed was ultrasonically cleaned with Ascent, and then further ultrasonically cleaned with isopropyl alcohol (IPA). Then, in order to improve the coatability of the catalyst precursor layer, the base layer was treated with _{O 2 plasma.}

A coating solution containing 70 mM FeCl ₃ , 10 mM iridium (Ir), 80 mM citric acid and 1 wt% PVA was prepared. The coating solution was applied to the surface of the base material on which the base layer was formed by the spin coating method. Then, the base material was heated at 200 ° C. for 1 minute to dry the coating solution to form a catalyst precursor layer having a thickness of 10 μm, and a catalyst base material for producing CNT aggregates was prepared.

The catalyst base material for producing a CNT aggregate is carried into a synthesis furnace, and while supplying 500 sccm of He, it is heated at 750 ° C. for 6 minutes to alloy and atomize the catalyst metal element and the co-catalyst metal element to form a metal catalyst. Fine particles were formed.

He was introduced into the synthesis furnace at 500 sccm, 20% acetylene (C ₂ H ₂ ) (100 sccm of acetylene diluted to 20% with helium was introduced) at 10 sccm, and water bubbled with nitrogen was introduced at 50 sccm as a catalyst activator, and the CNT aggregate was introduced. Was synthesized.

Further, the base material is taken out from the synthesis furnace at the stage where the metal catalyst fine particles are formed, and an image of the metal catalyst fine particles formed on the surface of the base material observed by an atomic force microscope (AFM) is shown in FIG. 3 (A). It was confirmed that metal catalyst fine particles having a particle size of 5 nm and a number density of 2 × 10 ¹¹ particles / cm ^{2 were formed.}

The Raman spectrum of the synthesized CNT aggregate is shown in FIG. 3 (B). For the Raman spectrum, an excitation wavelength of 532 nm was used using a Raman spectrophotometer (Thermoelectron). CNT aggregate of Example 1, the maximum peak intensity in the range of 1560 cm ^-1 or 1600 cm ^-1 or less G, and maximum peak intensity in the range of 1310cm ^-1 or 1350 cm ^-1 or less is represented by D Occasionally, the G / D ratio was 2.0. The yield of the CNT aggregate was 0.621 mg / cm ² , and the average height of the CNT aggregate was 345 μm.

(Example 2)
As Example 2, a catalytic base material for producing CNT aggregates was prepared in the same manner as in Example 1 except that a coating solution containing _{70 mM FeCl 3, 18 mM iridium, 88 mM citric acid and 1 wt% PVA was prepared.} The film thickness of the formed catalyst precursor layer was 10 μm.

Metal catalyst fine particles were formed under the same conditions as in Example 1. Then, the CNT aggregate was synthesized under the same conditions as in Example 1.

The base material is taken out from the synthesis furnace at the stage where the metal catalyst fine particles are formed, and the AFM image of the metal catalyst fine particles formed on the catalyst base material for producing CNT aggregates is shown in FIG. 4 (A). It was confirmed that metal catalyst fine particles having a particle size of 4 nm and a number density of 3 × 10 ¹¹ / cm ^{2 were formed on the catalyst base material for producing CNT aggregates.}

The Raman spectrum of the CNT aggregate of Example 2 measured under the same conditions as in Example 1 is shown in FIG. 4 (B). The G / D ratio of the CNT aggregate of Example 2 was 2.8. From this, it was confirmed that the CNT aggregate of Example 2 had a high degree of graphitization and high quality. The yield of the CNT aggregate was 0.489 mg / cm ² , and the average height of the CNT aggregate was 149 μm.

(Example 3)
As Example 3, a catalyst base material for producing CNT aggregates was prepared in the same manner as in Example 1 except that a coating solution containing _{70 mM FeCl 3, 10 mM iridium and 1 wt% PVA was prepared.} The film thickness of the formed catalyst precursor layer was 10 μm.

Metal catalyst fine particles were formed under the same conditions as in Example 1. Then, the CNT aggregate was synthesized under the same conditions as in Example 1.

The base material is taken out from the synthesis furnace at the stage where the metal catalyst fine particles are formed, and the AFM image of the metal catalyst fine particles formed on the catalyst base material for producing CNT aggregates is shown in FIG. 5 (A). It was confirmed that metal catalyst fine particles having a particle size of 4 nm and a number density of 4 × 10 ¹¹ / cm ^{2 were formed on the catalyst base material for producing CNT aggregates.}

The Raman spectrum of the CNT aggregate of Example 3 measured under the same conditions as in Example 1 is shown in FIG. 5 (B). The G / D ratio of the CNT aggregate of Example 3 was 2.3. From this, it was confirmed that the CNT aggregate of Example 3 had a high degree of graphitization and high quality. The yield of the CNT aggregate was 0.408 mg / cm ² , and the average height of the CNT aggregate was 92 μm.

(Example 4)
As Example 4, the metal catalyst was made into fine particles in the presence of oxygen. As Example 4, a catalyst base material for producing a CNT aggregate was produced in the same manner as in Example 2.

Example The CNT aggregate production catalyst substrate 4 is conveyed to the synthesis reactor, the oxygen _{(O 2)} of 500 sccm, while nitrogen _{(N 2)} and 1500sccm fed, and heated for 5 minutes at 750 ° C., the catalytic metal element And the co-catalyst metal element were alloyed and made into fine particles to form metal catalyst fine particles.

Then, while supplying 500 sccm of He to the synthesis furnace, it was heated at 750 ° C. for 6 minutes to remove _{O 2} and N _{2 from the inside of the synthesis furnace.} He was introduced into the synthesis furnace at 500 sccm, 20% acetylene (C ₂ H ₂ ) (100 sccm of acetylene diluted to 20% with helium was introduced) at 10 sccm, and water bubbled with nitrogen was introduced at 50 sccm as a catalyst activator, and the CNT aggregate was introduced. Was synthesized.

The base material is taken out from the synthesis furnace at the stage where the metal catalyst fine particles are formed, and the AFM image of the metal catalyst fine particles formed on the catalyst base material for producing CNT aggregates is shown in FIG. 6 (A). It was confirmed that metal catalyst fine particles having a particle size of 1.5 nm and a number density of 7 × 10 ¹¹ / cm ^{2 were formed on the catalyst base material for producing CNT aggregates.} Therefore, from the results of this example, it was demonstrated that the catalyst base material for producing CNT aggregates according to the present invention can be made into fine particles of a metal catalyst even in the presence of oxygen.

The Raman spectrum of the CNT aggregate of Example 4 measured under the same conditions as in Example 1 is shown in FIG. 6 (B). The G / D ratio of the CNT aggregate of Example 4 was 38.0. From this, it was confirmed that the CNT aggregate of Example 4 had a high degree of graphitization and high quality. The yield of the CNT aggregate was 0.009 mg / cm ² , and the average height of the CNT aggregate was 16 μm.

(Example 5)
As Example 5, a catalyst base material for producing a CNT aggregate was prepared in the same manner as in Example 1 except that a coating solution containing _{70 mM FeCl 3, 7 mM ruthenium (Ru), 77 mM citric acid and 1 wt% PVA was prepared.} The film thickness of the formed catalyst precursor layer was 10 μm.

Metal catalyst fine particles were formed under the same conditions as in Example 1. Then, the CNT aggregate was synthesized under the same conditions as in Example 1.

The base material is taken out from the synthesis furnace at the stage where the metal catalyst fine particles are formed, and an AFM image of the metal catalyst fine particles formed on the catalyst base material for producing CNT aggregates is shown in FIG. 7 (A). It was confirmed that metal catalyst fine particles having a particle size of 2 nm and a number density of 2 × 10 ¹¹ / cm ^{2 were formed on the catalyst base material for producing CNT aggregates.}

The Raman spectrum of the CNT aggregate of Example 5 measured under the same conditions as in Example 1 is shown in FIG. 7 (B). The G / D ratio of the CNT aggregate of Example 5 was 6.1. From this, it was confirmed that the CNT aggregate of Example 5 had a high degree of graphitization and high quality. Further, a scanning electron microscope (SEM) image of the CNT aggregate produced in Example 5 is shown in FIG. The yield of the CNT aggregate was 0.694 mg / cm ² , and the average height of the CNT aggregate was 370 μm.

(Example 6)
As Example 6, a catalytic base material for producing CNT aggregates was prepared in the same manner as in Example 1 except that a coating solution containing _{70 mM FeCl 3, 10 mM iridium, 80 mM citric acid, and 1 wt% glycerin was prepared.} The film thickness of the formed catalyst precursor layer was about 100 nm. In this example, since glycerin evaporates at a low temperature of 300 ° C. or lower, only citric acid acts as an alloying auxiliary substance.

Metal catalyst fine particles were formed under the same conditions as in Example 1. Then, the CNT aggregate was synthesized under the same conditions as in Example 1.

The base material is taken out from the synthesis furnace at the stage where the metal catalyst fine particles are formed, and the AFM image of the metal catalyst fine particles formed on the catalyst base material for producing CNT aggregates is shown in FIG. 9 (A). It was confirmed that metal catalyst fine particles having a particle size of 2 nm and a number density of 6 × 10 ¹⁰ pieces / cm ^{2 were formed on the catalyst base material for producing CNT aggregates.}

The Raman spectrum of the CNT aggregate of Example 6 measured under the same conditions as in Example 1 is shown in FIG. 9 (B). The G / D ratio of the CNT aggregate of Example 6 was 15.2. From this, it was confirmed that the CNT aggregate of Example 6 had a high degree of graphitization and was of high quality. The yield of the CNT aggregate was 0.142 mg / cm ² , and the average height of the CNT aggregate was 76 μm.

(Comparative Example 1)
As Comparative Example 1, a catalyst base material for producing a CNT aggregate was produced without using a co-catalyst metal element. As Comparative Example 1, a catalytic base material for producing CNT aggregates was prepared in the same manner as in Example 1 except that a coating solution containing 70 _{mM FeCl 3, 70 mM citric acid and 1 wt% PVA was prepared.} The film thickness of the formed catalyst precursor layer was 10 μm.

Metal catalyst fine particles were formed under the same conditions as in Example 1. Then, the CNT aggregate was synthesized under the same conditions as in Example 1.

The base material is taken out from the synthesis furnace at the stage where the metal catalyst fine particles are formed, and the AFM image of the metal catalyst fine particles formed on the catalyst base material for producing CNT aggregates is shown in FIG. 10 (A). It was confirmed that metal catalyst fine particles having a particle size of 5 nm and a number density of 1 × 10 ¹¹ / cm ^{2 were formed on the catalyst base material for producing CNT aggregates.}

The Raman spectrum of the CNT aggregate of Comparative Example 1 measured under the same conditions as in Example 1 is shown in FIG. 10 (B). The G / D ratio of the CNT aggregate of Comparative Example 1 was 3.3. However, the yield of the CNT aggregate was 0.029 mg / cm ² , and the average height of the CNT aggregate was 6 μm, and the amount of CNT synthesized was significantly reduced as compared with Example 1.

(Comparative Example 2)
As Comparative Example 2, a catalyst metal element and a co-catalyst metal element were formed into a film by a sputtering method to prepare a catalyst base material for producing a CNT aggregate. _{Alumina was deposited on the SiO 2} film on the surface of the base material on which the catalyst was placed by a sputtering method to form a base layer having a size of 40 nm or more, and then iron (Fe) was deposited at 2.5 nm by a sputtering method. Further, Ir was deposited at 0.4 nm by the sputtering method.

Metal catalyst fine particles were formed under the same conditions as in Example 1. Then, the CNT aggregate was synthesized under the same conditions as in Example 1.

The base material is taken out from the synthesis furnace at the stage where the metal catalyst fine particles are formed, and an AFM image of the metal catalyst fine particles formed on the catalyst base material for producing CNT aggregates is shown in FIG. 11 (A). It was confirmed that metal catalyst fine particles having a particle size of 0.9 nm and a number density of 6 × 10 ¹¹ / cm ^{2 were formed on the catalyst base material for producing CNT aggregates.}

The Raman spectrum of the CNT aggregate of Comparative Example 2 measured under the same conditions as in Example 1 is shown in FIG. 11 (B). The G / D ratio of the CNT aggregate of Comparative Example 2 was 10.4. However, the yield of the CNT aggregate was 0.007 mg / cm ² , and the average height of the CNT aggregate was 7 μm, and the amount of CNT synthesis was significantly reduced as compared with Example 1.

(Comparative Example 3)
As Comparative Example 3, a catalyst base material for producing a CNT aggregate was prepared without using a co-catalyst metal element, and a metal catalyst fine particle forming step was performed in an oxidizing atmosphere. As Comparative Example 3, a catalytic base material for producing CNT aggregates was prepared in the same manner as in Example 4 except that a coating solution containing 70 _{mM FeCl 3, 70 mM citric acid and 1 wt% PVA was prepared.} The film thickness of the formed catalyst precursor layer was 10 μm.

Metal catalyst fine particles were formed under the same conditions as in Example 4. Then, the CNT aggregate was synthesized under the same conditions as in Example 4.

The base material is taken out from the synthesis furnace at the stage where the metal catalyst fine particles are formed, and an AFM image of the metal catalyst fine particles formed on the catalyst base material for producing CNT aggregates is shown in FIG. 12 (A). A structure having a particle size of 1 nm or more could not be observed on the catalyst base material for producing CNT aggregates, and the formation of metal catalyst fine particles could not be confirmed.

The Raman spectrum of Comparative Example 3 measured under the same conditions as in Example 4 is shown in FIG. 12 (B). In Comparative Example 3, the peak of the G band indicating the presence of CNT was not observed. The yield of the CNT aggregate was 0 mg / cm ² .

(Reference example 1)
As Reference Example 1, an example in which a conventional catalyst base material for producing CNT aggregates is reduced with hydrogen to form fine particles is shown. As a reference example 1 _{, alumina was deposited by a sputtering method on a silicon edge having a SiO 2} film formed at 500 nm to form a base layer having a diameter of 40 nm or more.

Iron (Fe) was deposited on the base layer by a sputtering method at 1.8 nm.

The catalyst base material for producing CNT aggregates was carried into a synthesis furnace, _{and while supplying 500 sccm of hydrogen (H 2} ), it was heated at 750 ° C. for 6 minutes to atomize the catalyst metal element to form metal catalyst fine particles. Then, the CNT aggregate was synthesized under the same conditions as in Example 1.

The base material is taken out from the synthesis furnace at the stage where the metal catalyst fine particles are formed, and the AFM image of the metal catalyst fine particles formed on the catalyst base material for producing CNT aggregates is shown in FIG. 13 (A). It was confirmed that metal catalyst fine particles having a particle size of 2.8 nm and a number density of 6 × 10 ¹¹ / cm ^{2 were formed on the catalyst base material for producing CNT aggregates.}

The Raman spectrum of the CNT aggregate of Reference Example 1 measured under the same conditions as in Example 1 is shown in FIG. 13 (B). The G / D ratio of the CNT aggregate of Reference Example 1 was 8.0. From this, it was confirmed that the CNT aggregate of Reference Example 1 has a high degree of graphitization and high quality. The yield of the CNT aggregate was 2.208 mg / cm ² , and the average height of the CNT aggregate was 914 μm. From this result, it was shown that the catalyst base material for producing CNT aggregates shown in the above-mentioned Examples is effective for the synthesis of CNTs as in Reference Example 1.

100: Manufacturing equipment, 101: Substrate, 102: Underlayer, 103: Catalyst layer, 105: Substrate holder, 106: Catalyst precursor layer, 107: Metal catalyst fine particles, CNT, 110: Synthesis furnace, 141: 1st Gas supply pipe, 143: 2nd gas supply pipe, 145: 1st gas flow path, 147: 2nd gas flow path, 161: raw material gas cylinder, 163: atmosphere gas cylinder, 165: reduction gas cylinder, 167: catalyst activator cylinder, 171: First carbon concentration adjusting means, 173: Second carbon concentration adjusting means

Claims (11)

With the base material
A catalyst metal element selected from the Group VIIIB transition metal provided on the base material, a co-catalyst metal element selected from a noble metal element capable of forming an alloy with the catalyst metal element, and the catalyst during heating. A catalyst precursor layer containing an alloying auxiliary substance that prevents the metal element or the co-catalyst metal element from aggregating and promotes the mixing of the catalyst metal element and the co-catalyst metal element.
Only including,
In the catalyst precursor layer, when the number of elements of the catalyst metal element is M and the number of elements of the co-catalyst metal element is N, the N / M is 0.01 or more and 2 or less. For catalyst base material. The catalyst base material for producing an aggregate of carbon nanotubes according to claim 1, which has a base layer containing a metal oxide on the surface of the base material. The catalyst base material for producing a carbon nanotube aggregate according to claim 1 or 2, wherein the alloying auxiliary substance is a high molecular weight organic compound or a low molecular weight organic compound having two or more sites that coordinate with the catalyst metal element. .. The alloying auxiliary substance is selected from the group consisting of polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone and derivatives thereof, and ethylenediamine, bipyridine, citric acid, ethylenediaminetetraacetic acid, phenanthroline, crown ether, porphyrin, and derivatives thereof. The catalyst base material for producing an aggregate of carbon nanotubes according to any one of claims 1 to 3, which is one or more. The catalyst base material for producing a carbon nanotube aggregate according to any one of claims 1 to 4, wherein the alloying auxiliary substance is present in the catalyst precursor layer in an amount of 2% by weight or more. The catalyst base material for producing a carbon nanotube aggregate according to any one of claims 1 to 5 is produced.
By heating the catalyst precursor layer, metal catalyst fine particles containing the catalyst metal element and the co-catalyst metal element are formed on the substrate.
A method for producing a carbon nanotube aggregate, which comprises bringing a hydrocarbon gas into contact with the metal catalyst fine particles to grow the carbon nanotube aggregate. Alumina is deposited on the surface of the base material on which the metal catalyst fine particles are formed by a sputtering method to form an underlayer.
The base layer is O ₂ The method for producing an aggregate of carbon nanotubes according to claim 6, which comprises treating with plasma to form the catalyst precursor layer on the underlayer. The carbon nanotubes are obtained by applying a solution prepared by dissolving the metal compound containing the catalyst metal element, the metal compound containing the co-catalyst metal element, and the alloying auxiliary substance onto a substrate and drying the carbon nanotubes. The method for producing an aggregate of carbon nanotubes according to claim 6 or 7, wherein the catalyst base material for producing the aggregate is produced. By heating the catalyst precursor layer, the alloying auxiliary substance is thermally decomposed to generate a reducing gas.
The reducing gas reduces the catalyst metal element, and the catalyst metal element and the co-catalyst metal element are alloyed and made into fine particles to form the metal catalyst fine particles, according to any one of claims 6 to 8. The method for producing an aggregate of carbon nanotubes according to the above. The invention according to any one of claims 6 to 9, wherein the metal catalyst fine particles having a particle size in the range of 1 nm or more and 10 nm or less are formed on the base material at a number density of ^{1 × 10 10} particles / cm ^{2 or more.} A method for producing carbon nanotube aggregates. The method for producing a carbon nanotube aggregate according to any one of claims 6 to 10, wherein the carbon nanotube aggregate can be grown from the surface of the base material at a yield of 0.1 mg / cm ^{2 or more.}

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