KR101679693B1 - Method for preparing carbon nanotube and hybrid carbon nanotube composite - Google Patents

Abstract

Disclosed is a method for producing carbon nanotubes and a hybrid carbon nanotube composite capable of producing high purity carbon nanotubes on different kinds of carbon materials with high yield. In the method of manufacturing a carbon nanotube according to an embodiment of the present invention, a carbon nanotube growth support is formed on a carbon support, a carbon nanotube growth catalyst is supported on a carbon nanotube growth support, Carbon nanotubes are grown by growing carbon nanotubes on the growth supports.

Description

METHOD FOR PREPARING CARBON NANOTUBE AND HYBRID CARBON NANOTUBE COMPOSITE BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a method for producing carbon nanotubes and a hybrid carbon nanotube composite, and more particularly, to a method for manufacturing carbon nanotubes capable of producing high purity carbon nanotubes on different carbon materials at a high yield, Tube composite.

Carbon materials such as graphene, fullerene or carbon nanotubes have excellent physical properties and thus can be applied to a wide range of fields such as photovoltaic cells, field emission devices (FEDs), capacitors or batteries, Is progressing actively.

As a method for synthesizing carbon nanotubes among carbon materials, a metal oxide / metal catalyst carrier is prepared by supporting a transition metal (Fe, Co, or Ni) on a metal oxide support (Al ₂ O ₃ or MgO) There is a method of synthesizing by exposing / reacting to a high temperature carbon source. When carbon nanotubes are synthesized in this manner, carbon nanotubes having a yield of 500% or more can be obtained.

However, in the case of synthesized carbon nanotubes, the metal oxide itself used as a support for supporting the metal catalyst acts as an inorganic impurity, thereby deteriorating the purity of the carbon nanotubes. Accordingly, a complicated purification process for removing inorganic impurities may be required, and it is advantageous for various applications of carbon nanotubes to synthesize carbon nanotubes with high yield while minimizing the amount of unnecessary metal oxide.

If the support supporting the transition metal is replaced with a carbon material different from the carbon nanotubes which are not metal oxides, the purity of the synthesized carbon nanotubes can be improved . In addition, since the support itself is an electrically conductive and thermally conductive material, it may function as a conductive filler rather than an impurity, even if a support is detached from the carbon nanotube.

However, it is very unstable in terms of reproducibility and reliability to uniformly support the transition metal in a carbon material having low reactivity. Carbon nanotubes have been synthesized by surface treatment of carbon materials. Carbon nanotubes have been surface-treated by surface treatment using a functional group introduction by chemical treatment, introduction of an organic buffer layer or plating, A transition metal precursor such as ferrocene has been applied at high temperature by directly depositing the carbon precursor on a carbon material through a physical adsorption method.

This surface-treated carbon material was effective in the impurity problem, but there is a problem in synthesizing carbon nanotubes having a high yield on a carbon material because the yield of the carbon nanotubes after synthesizing the carbon nanotubes is less than 100% of the initial catalyst carrier mass there was.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a carbon nanotube manufacturing method and a hybrid carbon nanotube composite which can produce a high purity carbon nanotube on different kinds of carbon materials at high yield have.

According to an aspect of the present invention, there is provided a method of manufacturing a carbon nanotube, including: forming a carbon nanotube growth support on a carbon support; Supporting a carbon nanotube growth catalyst on the carbon nanotube growth support; And growing carbon nanotubes on the carbon nanotube growth support having the carbon nanotube growth catalyst supported thereon.

At this time, the carbon support may be selected from graphene, oxide graphene, graphene nanoplate, graphite, expanded graphite and carbon fiber, and the carbon nanotube growth promoter may be a metal oxide thin film layer. The metal oxide may be any one selected from Al ₂ O ₃ , MgO, SiO ₂ , CaO, and ZrO ₂ .

The carbon nanotube growth catalyst may be a metal catalyst. The metal catalyst may be any one of Fe, Mo, Ti, V, Cr, Mn, Ni, Co, Cu, Cd, Zn, Ru, Pd, Ag, Metal or an alloy thereof.

The carbon nanotube manufacturing method may further include separating the grown carbon nanotubes from the carbon support.

According to another aspect of the present invention, Carbon nanotube growth support formed as thin film on carbon support surface: Carbon nanotube growth catalyst supported on carbon nanotube growth support; And carbon nanotubes grown on the carbon nanotube growth support having the carbon nanotube growth catalyst supported thereon.

According to the method for manufacturing carbon nanotubes according to the embodiment of the present invention, the support for synthesizing carbon nanotubes can be replaced with a carbon material having the same component as that of the conventional metal oxide, thereby improving the reduction and purity of inorganic impurities in the carbon nanotube It is possible to synthesize carbon nanotubes in a high yield on a carbon material, thereby enabling commercial mass production.

In addition, since the carbon support itself includes an electrically conductive and thermally conductive carbon material, the carbon nanotube can be used as a hybrid carbon nanotube composite without separating the carbon nanotube from the carbon support even after the carbon nanotube is grown. It is not necessarily required and the performance can be further improved.

FIG. 1 is a view for explaining a method of manufacturing a carbon nanotube according to an embodiment of the present invention.
FIG. 2 is a view showing a modified surface of carbon nanotubes grown on a carbon support and its enlarged views and analysis results. FIG.
FIG. 3 is a view showing a state of a carbon support on which a carbon nanotube growth catalyst is supported, enlarged views thereof, and analysis results thereof.
4 is a view showing carbon nanotubes grown on a carbon nanotube growth support and its enlarged views.
5 is a graph showing the results of Raman spectrum analysis of carbon nanotubes.
6 is a graph showing the yield of carbon nanotubes according to growth time when carbon nanotubes are manufactured.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a view for explaining a method of manufacturing a carbon nanotube according to an embodiment of the present invention. The method for fabricating a carbon nanotube according to the present invention includes the steps of: forming a carbon nanotube growth support member (120) on a carbon support (110); Supporting the carbon nanotube growth catalyst (130) on the carbon nanotube growth support member (120); And growing the carbon nanotubes 140 on the carbon nanotube growth support member 120 on which the carbon nanotube growth catalyst 130 is supported.

In order to produce carbon nanotubes according to the present invention, a support made of a carbon-based material is used as a support for growing carbon nanotubes. Hereinafter, the carbon support means a support made of a carbon-based material. Examples of the carbon-based material include graphene, graphite and other carbon isotopes, and examples thereof include graphene, oxide graphene, graphene nanoplate, graphite, expanded graphite, and carbon fiber.

The carbon nanotube growth support member 120 for growing carbon nanotubes is formed on the carbon support 110. The carbon nanotube growth support member 120 is a seed for supporting a carbon nanotube catalyst. In general, a metal catalyst is used as a catalyst. In order to support the metal catalyst, a carbon nanotube growth support member 120 Metal oxides may be used. Conventionally, the carbon nanotubes 140 are obtained by supporting the catalyst on the metal oxide itself, growing the carbon nanotubes 140, and then separating the carbon nanotubes 140. However, even after the carbon nanotubes 140 are separated, A metal oxide having low electrical conductivity or low thermal conductivity remains and can act as an inorganic impurity.

Accordingly, in the present invention, a support is formed of the same carbon material as the carbon nanotubes 140 without using a metal oxide as a support, a metal oxide layer is formed on the surface of the carbon support 110, The nanotubes 140 are grown.

The carbon nanotube growth support member 120 may be formed, for example, by coating a metal oxide thin film on a carbon support 110 using a hydrolysis reaction.

The metal oxide used as the carbon nanotube growth support material 120 may be selected from Al ₂ O ₃ , MgO, SiO ₂ , CaO, and ZrO ₂ , and any of the porous metal oxides capable of supporting the metal catalyst may be used have. Since the purity of the carbon nanotubes 140 produced according to the residual metal oxide may be lowered, it is preferable that the metal oxide is contained in the entire process as small as possible, but it is required to sufficiently support the metal catalyst. Therefore, a metal oxide thin film layer may be formed on the surface of the carbon support 110 to secure a wide area required for growing the carbon nanotubes 140 as much as possible and to minimize the amount of the metal oxide.

The carbon nanotube growth catalyst 130 may be a metal catalyst. The transition metal may be a single metal such as Fe, Mo, Ti, V, Cr, Mn, Ni, Co, Cu, Cd, Zn, Ru, Pd, Ag, Pt and Au, have. The carbon nanotube growth catalyst 120 can be used in consideration of the amount of the carbon nanotubes 140 to be produced. When the amount of the metal catalyst supported on the carbon nanotube growth support 120 is controlled, 140 can also be controlled.

The carbon nanotubes 140 are grown on the carbon nanotube growth catalyst 130 supported on the carbon nanotube growth support member 120. The shape of the carbon nanotubes 140 to be manufactured is not limited. For example, the shapes of the single-wall carbon nanotubes, the functionalized single wall carbon nanotubes, the double wall carbon nanotubes, the functionalized double wall carbon nanotubes, Or functionalized multi-walled carbon nanotubes.

As a method of growing the carbon nanotubes 140, a chemical vapor deposition (CVD) method may be used. The chemical vapor deposition process can be performed by any one of a variety of chemical vapor deposition methods such as chemical vapor deposition (TCVD), rapid chemical vapor deposition (RTCVD), inductively coupled plasma chemical vapor deposition (ICP-CVD), low pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition Vapor deposition (MOCVD), or plasma chemical vapor deposition (PECVD).

In order to grow the carbon nanotubes 140, a carbon support carrying the carbon nanotube growth catalyst 130 is introduced into a growth reactor, the temperature of the reactor is increased to a predetermined temperature, and then a carbon source (carbon source) The carbon nanotubes 140 can be grown by flowing a reactive gas. At this time, it is possible to control the diameter or length of the carbon nanotubes 140 by controlling the pressure of the reactor or the flow rate of the reaction gas. The carbon source may be an aliphatic hydrocarbon or an aromatic hydrocarbon. Examples of such carbon sources include, but are not limited to, methane, ethane, propane, butane, ethylene, acetylene, and benzene.

The carbon nanotube manufacturing method may further include separating the grown carbon nanotubes 140 from the carbon support 110. Alternatively, according to another aspect of the present invention, a carbon support 110; A carbon nanotube growth support 120 formed in the form of a thin film on the surface of the carbon support 110; a carbon nanotube growth catalyst 130 supported on the carbon nanotube growth support 120; And a carbon nanotube 140 grown on the carbon nanotube growth support member 120 on which the carbon nanotube growth catalyst 130 is supported. The tube 140 can be used together without separating it from the carbon support 110.

In other words, since the carbon support 110 is also a carbon-based material, it exhibits properties such as thermal conductivity and electrical conductivity similar to the carbon nanotubes 140, and thus can be used as a composite such as carbon nanotubes . If the carbon nanotubes 140 are used as the hybrid carbon nanotube composite 150, the carbon nanotubes 140 may be separated from the carbon nanotubes 140. Since the carbon nanotubes 140 are similar to each other, they may act as conductive fillers instead of inorganic impurities. But also as the hybrid carbon nanotube composite 150.

If the carbon nanotube composite was a direct carbon nanotube grown on a carbon support, higher purity could be expected. However, growing carbon nanotubes directly on a carbon support requires carbon nanotube growth The yield of the catalyst is very low because it is difficult to carry the catalyst. Therefore, according to the present invention, a carbon nanotube or a carbon nanotube composite having a relatively high purity can be produced at a high yield and can be used for a solar cell, a field emission device (FED), a capacitor, a battery, It can be used in a wide range of fields. In addition, since the carbon nanotube composite has a very large specific surface area, it can exhibit high physical properties even when a small amount is added to other composite materials.

Hereinafter, specific test examples of the present invention will be described. However, the following test examples do not limit the present invention.

According to an embodiment of the present invention, a carbon nanotube manufacturing method includes:

(1) a step of forming a carbon nanotube growth support on a carbon support, that is, a carbon material surface modification step for supporting a metal catalyst for synthesizing carbon nanotubes

(2) supporting the carbon nanotube growth catalyst on the carbon nanotube growth support, that is, supporting the metal catalyst on the surface of the surface-modified carbon material, and

(3) growing carbon nanotubes on the carbon nanotube growth support having the carbon nanotube growth catalyst supported thereon, that is, synthesizing carbon nanotubes on the carbon material.

This will be described in detail on the basis of the following test examples and test results.

(1) Carbon material surface modification process for metal catalyst support for synthesizing carbon nanotubes:

A solution of magnesium methoxide (Mg (OCH ₃ ) ₂ ) diluted to 6-8% in methanol was uniformly mixed with a graphene nanoplate as a carbon support in a mass ratio of 18: 1, To slowly induce the hydrolysis reaction described below.

_{Mg (OCH 3) 2 + H} 2 O, Mg (OH) (OCH 3) + CH 3 OH, Mg (OH) (OCH 3) + H 2 O Mg (OH) 2 + CH 3 OH

Mg (OH) ₂ , a metal oxide, is uniformly coated on the surface of the graphene nanoflurane by a hydrolysis reaction. The solvent of the reaction solution is selectively removed using a rotary condenser, and finally the carbon nanotube growth promoter To obtain a graphene nanoplate powder in which Mg (OH) ₂ is a surface-treated carbon support.

FIG. 2 is a view showing a modified surface of a carbon nanotube growth support, Mg (OH) ₂ , formed on a graphene nanoplate as a carbon support, and enlarged views and analysis results thereof. The A ₁ of Figure 2 graphene nano-plates, the A ₂ and the yes enlarged SEM image of a pin nano plate A ₁ shown, A ₃ in the Mg (OH) ₂ is formed in this modified graphene nano-plate surface A ₄ shows the enlarged SEM image of A ₄ , and A ₅ shows the TEM surface morphology of surface modified graphene nanoplate. A ₆ and A ₇ show the results of EDX analysis of the surface of the graphene nanoplate surface-modified, and it was confirmed that the Mg (OH) ₂ thin film was formed on the surface by confirming the Mg peak and the O peak.

(2) Surface-modified carbon material On-surface metal catalyst support:

The graphene nanoparticle powder surface treated with Mg (OH) ₂ was ultrasonically dispersed in water, and then ammonium molybdate tetrahydrate (NH ₃ ) ₆ Mo ₇ O ₂₄ 4H ₂ O ), Iron nitrate (Fe (NO ₃ ) ₃ 9H ₂ O) and polyethylene glycol (PEG) are successively mixed and homogeneously mixed for 1 hour under stirring on a 110 ° C hot plate.

The homogeneous mixed solution was transferred to an alumina boat, and water and methanol as a solvent were removed from the hot plate at 150 ° C., followed by heat treatment at 650 ° C. in a high-temperature drying furnace for 10 minutes to finally obtain a graphene nanoplate A carbon material / metal catalyst carrier carrying a metal catalyst (Fe-Mo) as a carbon nanotube growth catalyst is prepared.

FIG. 3 is a view showing a state of a carbon support on which a carbon nanotube growth catalyst is supported, enlarged views thereof, and analysis results thereof. In B ₁ of Figure 3 the carbon nanotube is formed seongjangdam member surface is modified graphene nano plate (Fe-Mo) metal catalyst is graphene nano-plates of the loading state, B ₂ and B ₃ in the metal of the B1 An enlarged SEM image of the graphene nanoplate carrying the catalyst is shown, and a TEM surface morphology of the graphene nanoplate carrying the (Fe-Mo) metal catalyst is shown in B ₄ . B ₅ and B ₆ show EDX analysis of the surface of the graphene nanoplate carrying the metal catalyst. Mg (OH) ₂ thin films were observed on the surface by confirming both Mg peak, O peak, Fe peak and Mo peak. And the Fe and Mo metal catalysts were supported (the Cu peak is the peak of the Cu TEM grid used for TEM sample loading).

(3) Synthesis of carbon nanotubes on carbon material:

The carbon material / metal catalyst carrier prepared in (2) reacts with a carbon source in a high-temperature quartz tube through thermal chemical vapor deposition (CVD), specifically at 900 ° C., Ar (500 sccm ) Atmosphere for 40 minutes, and then CH ₄ / H ₂ CNTs are synthesized for 60-180 minutes in a mixed gas atmosphere (500 sccm / 25 sccm) to fabricate a carbon nanotube array grown on a carbon material.

4 is a view showing carbon nanotubes grown on a carbon nanotube growth support and its enlarged views. In FIG. 4, carbon nanotubes grown on the surface-modified graphene nanoparticles and their enlarged SEM images are shown in C ₁ to C ₄ , and in C ₅ , images of carbon nanotube TEM surface grown from the metal catalyst and C ₆ And the carbon nanotubes grown in C ₇ are further enlarged.

5 is a graph showing the results of Raman spectrum analysis of the carbon nanotube produced. The Raman spectrum analysis was performed to confirm the crystallinity of the carbon nanotubes, and it was confirmed that the hexagonal structure of the carbon was defective. As a result, the _IG / I _D ratio was about 1.0. Considering that a commercial I _G / I _D ratio of carbon nanotubes is 0.7 to 0.8 can be seen that the quality of the carbon nanotubes.

6 is a graph showing the yield of carbon nanotubes according to growth time. As shown in FIG. 6, a synthesis yield correlation graph of carbon nanotubes synthesized at the time of the process using the thermochemical vapor deposition method is shown in this test example. The synthesis yield was calculated as [(mass of catalyst post catalyst after synthesis - mass of catalyst carrier before synthesis) / mass of catalyst carrier before synthesis] * 100.

In the case of growing carbon nanotubes directly on a support using a carbon material support, the metal oxide thin film is formed as a carbon nanotube growth support on a carbon support as in this test example, while a low yield of about 100% is obtained , And when carbon nanotubes were grown by supporting a catalyst for growing carbon nanotubes, the synthesis yields were 400% after 120 minutes, and 1,000% after 180 minutes. It is predicted that the synthesis yield will be about 1,000%, and that this value will be higher in the production process through mass production since it is the yield in the laboratory condition.

Although the synthesis yield is not higher than that of the conventional technology using the metal oxide itself as a growth support, it has been confirmed that the amount of inorganic impurities is reduced by at most 10% more than that of the prior art, assuming that the synthesis yield of carbon nanotubes is the same. Considering the fact that the metal oxide acts as an inorganic impurity in the conventional case, and thus a high cost and complicated purification process has to be additionally performed, and a residual amount of inorganic impurities may remain in the final product, the product reliability is not high. A carbon nanotube or a carbon nanotube composite having a higher purity can be obtained at a high yield by using a carbon support having the same material as that of the carbon nanotubes. Thus, an efficient manufacturing process can be performed.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, many modifications and changes may be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

110 carbon support
120 Carbon Nanotube Growth Delay
130 Carbon Nanotube Growth Catalyst
140 carbon nanotubes
150 Hybrid Carbon Nanotube Composite

Claims (8)

Forming a metal hydroxide thin film layer on the carbon support;
Supporting a carbon nanotube growth catalyst on the metal hydroxide thin film layer;
Heat treating the metal hydroxide thin film layer supporting the carbon nanotube growth catalyst to convert the metal hydroxide thin film layer into a metal oxide thin film layer as a carbon nanotube growth supporting material; And
And growing carbon nanotubes on the metal oxide thin film layer.
The method according to claim 1,
Wherein the carbon support is any one selected from graphene, oxide graphene, graphene nanoplate, graphite, expanded graphite, and carbon fiber.
delete The method according to claim 1,
The metal oxide,
Al ₂ O ₃ , MgO, SiO ₂ , CaO, and ZrO ₂ .
The method according to claim 1,
Wherein the carbon nanotube growth catalyst is a metal catalyst.
The method of claim 5,
The metal catalyst may be any one selected from the group consisting of Fe, Mo, Ti, V, Cr, Mn, Ni, Co, Cu, Cd, Zn, Ru, Pd, Ag, Pt, Method of manufacturing nanotubes.
The method according to claim 1,
And separating the grown carbon nanotubes from the carbon support.
Carbon support;
A carbon nanotube growth promoter formed in a thin film on the surface of the carbon support;
A carbon nanotube growth catalyst supported on the carbon nanotube growth support; And
And carbon nanotubes grown on the carbon nanotube growth support on which the carbon nanotube growing catalyst is supported,
Wherein the carbon nanotube growth support is a metal oxide thin film layer formed by forming a metal hydroxide thin film layer on the carbon support and supporting the carbon nanotube growth catalyst on the metal hydroxide thin film layer and then performing heat treatment.

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