CN101007631A - Mono-layer carbon nanotube and its preparation method, and electronic element preparation method - Google Patents

Abstract

Provided is a method for preparing single-layer carbon nanotubes, which is a method that can easily prepare high-quality single-layer carbon nanotubes with controllable structures, and can prepare single-layer carbon nanotubes with extremely small diameters, and the diameter A method for single-walled carbon nanotubes with a controllable distribution range. Single-walled carbon nanotubes are grown under normal pressure by chemical vapor deposition using a gas obtained by vaporizing alcohol such as ethanol or an aqueous solution of alcohol as a reaction gas. The reaction is carried out by introducing a gas obtained by vaporizing alcohol or an aqueous solution of alcohol by natural evaporation or the like outside the reaction site of the chemical vapor deposition apparatus into the reaction site. The concentration of alcohol in the aqueous alcohol solution ranges from 50% to 95%. Also provided are a single-layer carbon nanotube prepared by the method and a method for preparing an electronic component by using the single-layer carbon nanotube.

Description

Single-walled carbon nanotubes, preparation method thereof, and preparation method of electronic components

technical field

The present invention relates to a method for preparing single-walled carbon nanotubes, a method for preparing single-walled carbon nanotubes and electronic components, for example, preferably applied to various electronic components using single-walled carbon nanotubes.

Background technique

Single-walled carbon nanotubes (SWNTs) have unique electrical, mechanical, electro-optical and electro-mechanical properties, so they have always been regarded as future nanoelectronic components such as field emission devices, field effect transistors, single-electron transistors, and molecular sensors. Attractive structural units (for example, refer to Non-Patent Documents 1 to 5). In order to realize such attractive applications, it is necessarily desirable to prepare high-quality single-walled carbon nanotubes with a controlled structure. In order to prepare single-walled carbon nanotubes, a lot of effort has been put into the past 10 years. Various techniques have been developed to produce high-quality single-walled carbon nanotubes in high yields and at low cost, including: arc discharge (for example, refer to Non- Patent Document 6), laser ablation (for example, refer to Non-Patent Document 7), and chemical vapor deposition (CVD) (for example, refer to Non-Patent Documents 8 to 10). Applications of single-walled carbon nanotubes (for example, see Non-Patent Document 11) and basic science (for example, see Non-Patent Documents 12 to 16) require new routes and flexibility in production.

The above-mentioned CVD method is generally regarded as a powerful method for preparing high-quality single-walled carbon nanotubes at low cost. Therefore, many studies have been intensively conducted to optimize the CVD method by exploring the catalyst composition, carrier/substrate material, reaction temperature, and carbon source gas (see, for example, Non-Patent Documents 17 to 20). Recently, it has been reported that ethanol is an ideal carbon source for producing high-quality single-walled carbon nanotubes by CVD under reduced pressure (see, for example, Non-Patent Documents 21 to 23). In addition, it has also been proposed that a carbon source formed from a compound having an oxygen atom or a mixture of a compound having an oxygen atom and a compound having a carbon atom be brought into contact with a catalyst at a heating temperature, and under reduced pressure, the preparation of a single The method of layering carbon nanotubes, as the example of above-mentioned carbon source, can enumerate alcohols such as ethanol or ethers; As the example of above-mentioned mixture, can enumerate the mixture of water and hydrocarbons such as acetylene, or the mixture of _NOx , _SOx and acetylene etc. A mixture of hydrocarbons, etc. (for example, refer to Patent Document 1).

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Huang, Sh.M.; Cai, X.Y.; Liu, J., J.Am.Chem.Soc.2003, 125, 5636

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Tanaka, K.; Yamabe, T.; Fukui, K., The Science and Technology of Carbon Nanotubes; Elsevier: Oxford, 1999

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Wong, S.; Joselevich, E.; Woolley, A.; Cheung, C.; Lieber, C., Nature 1998, 394, 52

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Wang, X.B.; Liu, Y.Q.; Zhu, D.B., Chem.Commun.2001, 751

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Wang, X.B.; Liu, Y.Q.; Zhu, D.B., Adv. Mater. 2002, 14, 165

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Wang, X.B.; Liu, Y.Q.; Hu, P.A.; Yu, G.;

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Song, L.; Ci, L.J.; Zhou, Zh.P.; Xie, S.Sh., Adv. Mater.2004, 16, 1529

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Huang, Sh. M.; Woodson, M.; Smalley, R.; Liu, J., Nano Lett. 2004, 4, 1025

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Shi, Z.J.; Okazaki, T.; Shimada, T.; Sugai, T.; Suenaga, K.;

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Murakami, Y.; Einarsson, E.; Edamura, T.; Maruyama, S., Carbon 2005, 43, 2664

[Patent Document 24]

International Publication No. 03/068676 Pamphlet

Contents of the invention

However, when using the CVD method to prepare single-walled carbon nanotubes under reduced pressure, it is difficult to control the growth parameters of single-walled carbon nanotubes, so it is difficult to prepare high-quality single-walled carbon nanotubes with a controlled structure. .

Therefore, the problem to be solved by the present invention is to provide a high-quality single-walled carbon nanotube that can be easily prepared with a controlled structure, and can easily prepare a single-walled carbon nanotube containing an extremely small diameter, and the diameter A method for a single-layer carbon nanotube with an extremely narrow distribution range, a single-layer carbon nanotube prepared by the method and a method for preparing an electronic component by using the method are provided.

In order to solve the above-mentioned problems, the first aspect of the present invention is a method for preparing single-walled carbon nanotubes, which is characterized in that: using a gas obtained by vaporizing alcohol or an aqueous solution of alcohol as a reaction gas, using a chemical vapor deposition method, Single-walled carbon nanotubes were grown under normal pressure.

The second aspect of the present invention is a single-layer carbon nanotube, which is characterized in that: the single-layer carbon nanotube uses gas obtained by vaporizing alcohol or an aqueous solution of alcohol as a reaction gas, and utilizes a chemical vapor deposition method. Produced by growing single-walled carbon nanotubes under pressure.

The third aspect of the present invention is a method for preparing electronic components using single-layer carbon nanotubes, which is characterized in that: using a gas obtained by vaporizing alcohol or an aqueous solution of alcohol as a reaction gas, using a chemical vapor deposition method, in normal The above-mentioned single-walled carbon nanotubes were grown by pressing.

In the present invention, typically, the reaction is performed by introducing a gas obtained by vaporizing alcohol or an aqueous solution of alcohol by natural evaporation or the like outside the reaction site of the chemical vapor deposition apparatus into the reaction site. The range of alcohol concentration (volume concentration) in the aqueous solution of alcohol is greater than 0% and less than 100%. As long as it is within this range, the alcohol concentration is basically not limited, and if the alcohol concentration is 75% or above, and the closer to 100% , the more able to prepare single-walled carbon nanotubes with smaller diameters, if the alcohol concentration is 50% to 95%, preferably 50% to 80%, it is possible to prepare single-walled carbon nanotubes with a narrow diameter distribution, especially when When the alcohol concentration is 70% to 80%, single-layer carbon nanotubes with extremely narrow diameter distribution can be prepared.

The growth temperature of single-walled carbon nanotubes is generally 500°C to 1500°C, preferably 650°C to 900°C, and more preferably 800°C to 900°C, but is not limited thereto. The growth of single-walled carbon nanotubes is typically carried out by bringing a gas obtained by vaporizing alcohol or an aqueous solution of alcohol into contact with a metal catalyst at the growth temperature. As the metal catalyst, various known catalysts conventionally used for the growth of carbon nanotubes can be used.

As the alcohol, basically any alcohol can be used, and it may be a monohydric alcohol or a polyhydric alcohol, and may be a saturated alcohol or an unsaturated alcohol. In general, monohydric alcohols with a small number of carbon atoms are liquid at normal temperature and are arbitrarily mixed with water, since an aqueous solution with a high alcohol concentration can be easily prepared, and thus is preferable. Examples of the alcohol specifically include methanol, ethanol, 1-propanol, 2-propanol (isopropanol), 1-butanol, 2-butanol (sec-butanol), and 2-methyl-1-propanol (isobutanol), 2-methyl-2-propanol (tert-butanol), etc., but not limited thereto.

By adjusting the concentration of alcohol in the aqueous alcohol solution and/or the vaporization rate of the aqueous alcohol solution, the diameter and/or diameter distribution of the single-layer carbon nanotubes can be controlled. The vaporization rate of the aqueous alcohol solution can be adjusted, for example, by changing the temperature of the container containing the aqueous alcohol solution.

It is preferable to refine the composition of the product after forming the single-walled carbon nanotubes by the chemical vapor deposition method. Since the product generally contains amorphous carbon, metal impurities, etc. in addition to single-walled carbon nanotubes, this purification is performed to remove them. The purification is preferably performed by acid treatment with hydrochloric acid, reflux with nitric acid, and air oxidation.

This single-walled carbon nanotube can be applied to any device as long as it is a device utilizing its unique electrical, mechanical, electro-optical or electro-mechanical characteristics. For example, as electronic components using the single-walled carbon nanotubes, specifically, field emission elements, field effect transistors (FETs) (including thin film transistors (TFTs)), single electron transistors, molecular sensors, solar cells, photoelectric Conversion element, light emitting element, memory, etc.

In the present invention constituted as above, by using the chemical vapor deposition method to grow the single-walled carbon nanotubes under normal pressure, it is easier to grow the single-walled carbon nanotubes than the case of growing the single-walled carbon nanotubes under reduced pressure by the chemical vapor deposition method. Control of growth parameters facilitates the growth of high-quality single-walled carbon nanotubes with controlled structures. In addition, by using a gas obtained by vaporizing alcohol or an aqueous alcohol solution as a reaction gas, it is possible to grow single-walled carbon nanotubes including extremely small-diameter single-walled carbon nanotubes with extremely narrow diameter distribution widths.

According to the present invention, it is possible to easily prepare high-quality single-walled carbon nanotubes having a controlled structure, and to easily prepare single-walled carbon nanotubes containing extremely small-diameter single-walled carbon nanotubes and having an extremely narrow diameter distribution. Tube. Furthermore, by using the single-walled carbon nanotubes produced by this method, high-performance electronic elements can be obtained.

Description of drawings

FIG. 1 is a cross-sectional view showing the structure of a CVD apparatus used in one embodiment of the present invention.

Fig. 2 is a diagram showing a Raman spectrum of a sample immediately after preparation using an ethanol concentration of 100% in one example of the present invention.

Fig. 3 is a schematic diagram showing a Raman spectrum of a sample immediately after nitric acid reflux with 100% ethanol concentration in an example of the present invention.

Fig. 4 is a schematic diagram showing a Raman spectrum after final purification of a sample immediately after preparation using an ethanol concentration of 100% in an example of the present invention.

Fig. 5 a～Fig. 5 d is the sample that uses the ethanol concentration of 100% to just prepare in one embodiment of the present invention, the sample after HCl treatment, the sample after _HNO reflux, and the sample after final refining A picture-substituting photograph of the SEM image.

FIG. 6 is a photograph substituted for a photograph showing a TEM image of a sample immediately after preparation to final purification using an ethanol concentration of 100% in one example of the present invention.

Fig. 7 is a schematic diagram showing the results of thermogravimetric analysis of samples immediately after preparation using an ethanol concentration of 100% in one example of the present invention.

8 is a schematic diagram showing the results of thermogravimetric analysis of samples immediately after preparation using 100% ethanol concentration up to HCl treatment in one example of the present invention.

9 is a schematic diagram showing the results of thermogravimetric analysis of samples immediately after preparation using 100% ethanol concentration up to reflux with HNO ₃ in one example of the present invention.

10 is a schematic diagram showing the results of thermogravimetric analysis of samples immediately after preparation to final purification using an ethanol concentration of 100% in one example of the present invention.

Fig. 11 is a schematic diagram showing the measurement results of the diameter distribution of single-walled carbon nanotubes grown with varying concentrations of ethanol in one example of the present invention.

Detailed ways

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In this embodiment, a metal catalyst is formed on a substrate, and a gas obtained by vaporizing alcohol (carbon source) or an aqueous solution of alcohol is used as a reaction gas to synthesize single-walled carbon nanotubes at normal pressure by the CVD method. At this time, alcohol or an aqueous solution of alcohol is vaporized outside the reaction part of the CVD apparatus (the part of the reaction tube protruding into the furnace) to obtain a gas, and the gas is introduced into the reaction part to perform the reaction. Then, the composition of the thus-synthesized single-walled carbon nanotubes is refined.

The substrate for growing single-walled carbon nanotubes is a substrate formed of inorganic materials and/or organic materials, and the material can be selected according to needs. As the substrate formed of an inorganic material, for example, a silicon substrate (including a substrate on which a _SiO2 film is formed on the surface), a glass substrate, a quartz substrate, or the like can be used. As the substrate formed of an organic material, for example, a polymer substrate can be used. As the substrate formed of an inorganic material and an organic material, a substrate obtained by combining these materials can be used.

As the metal catalyst formed on the substrate, metals such as Fe, Co, Ni, Mo, Pt, Pd, Rh, Ir, etc. or a combination of two or more of these metals can be used, such as Fe—Co, Ni-Co, Fe-Mo, Co-Mo, etc., but not limited to these substances. Typically, the metal catalyst is supported on a specified carrier. As the carrier, for example, MgO, silica, alumina, zeolite, zirconia, titania, etc. can be used, but not limited to these.

The growth temperature is 500°C to 1500°C, preferably 650°C to 900°C, more preferably 800°C to 900°C.

The alcohol concentration in the alcohol aqueous solution is more than 0% and less than 100%, but is preferably 50% to 95%, more preferably 50% to 80%, and still more preferably 70% to 80%. As the alcohol, for example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, etc. can be used .

According to this embodiment, a gas obtained by vaporizing alcohol or an aqueous solution of alcohol is used as a reaction gas, and single-walled carbon nanotubes are grown under normal pressure by the CVD method, so that high carbon nanotubes having a controlled structure can be easily produced. Quality Single Wall Carbon Nanotubes. Furthermore, it is possible to easily produce single-walled carbon nanotubes including extremely small single-walled carbon nanotubes having a diameter of, for example, 0.6 to 1.8 nm and having an extremely narrow diameter distribution width of, for example, 0.6 to 0.7 nm.

Example

(1) Preparation of catalyst

As a catalyst, Fe—Co was prepared by a conventional chemical impregnation method. Specifically, first, a metal nitrate solution was prepared by dissolving iron nitrate (Fe(NO ₃ ) ₃ 9H ₂ O) and cobalt nitrate (Co(NO ₃ ) ₃ 9H ₂ O) in ethanol (typically 40 ml) . Next, magnesium oxide (MgO) obtained by decomposing magnesium carbonate salt was added to the solution as a carrier. Next, in order to make the mixture thus prepared homogeneous, it was subjected to ultrasonic treatment for 3 hours. Ethanol was removed from the mixture using a rotary evaporator, and the resulting material was dried at 115°C for 12 hours. Afterwards, the material is made into a powder. The total amount of the catalyst in the MgO carrier was fixed at 10% by weight, and the molar ratio of the transition metal was Fe/Co=1:2.

(2) Atmospheric pressure CVD

FIG. 1 shows a CVD apparatus designed by the present inventors for producing single-walled carbon nanotubes under normal pressure. As shown in FIG. 1 , a quartz tube 11 as a reaction tube is placed in a furnace 12 . Both ends of the quartz tube 11 are protruded to the outside of the furnace 12 . The temperature of the furnace 12 is measured by a thermocouple 13 and controlled by a temperature control device 14 . Inside one end of the quartz tube 11 located outside the furnace 12, a container 16 filled with ethanol or an aqueous ethanol solution 15 is placed. The concentration of ethanol or ethanol aqueous solution 15 is 100%-50%. About 1 g of a catalyst 18 composed of MgO supporting Fe/Co fine particles was loaded on the quartz boat 17 as catalyst metal fine particles, and the quartz boat 17 was inserted into the quartz tube 11 at the center of the furnace 12 . Then, the ethanol gas or the gas of ethanol and water gasified from the ethanol or ethanol aqueous solution 15 in the container 16 is transported by using the Ar/H ₂ mixed gas flow (Ar: 250ml/min, H ₂ : 20ml/min). Single-walled carbon nanotubes are produced by CVD at 850° C. under normal pressure, typically with a reaction time of 30 minutes. The vaporization rate of ethanol or ethanol aqueous solution 15 is controlled by the following method: fix iron piece 19 on the bottom surface of container 16 in advance, move container 16 by making the magnet 20 that is arranged on the outside of quartz tube 11 move along quartz tube 11. Move to change the distance from the furnace 12, and use the radiant heat of the heated quartz tube 11 to control the temperature change of ethanol or ethanol aqueous solution 15.

(3) refined

The composition refining process is applied to the sample just after being prepared by the atmospheric pressure CVD method. First, the catalyst (both the MgO support and the metal fine particles) was removed by acid treatment with concentrated hydrochloric acid (HCl). Typically, the freshly prepared sample is placed in 50 ml of 6N concentrated hydrochloric acid while being subjected to ultrasonic treatment for 30 minutes. Next, in order to remove amorphous carbon, residual metal particles, and MgO support, the HCl-treated sample was refluxed in 4N nitric acid (HNO ₃ ) solution at 120° C. for 12 hours. The resulting sample was filtered and washed with distilled water until the filtrate became transparent in color. In the final stage of the refining process, the sample was heated in air at 470°C for 30 minutes, and then treated with 6N concentrated hydrochloric acid to remove residual impurities. After rinsing the sample and allowing it to dry at 120° C., a black to grayish thin pad was finally obtained.

(5) Characterization

Using a scanning electron microscope (SEM, S-4300 produced by Hitachi, 15kV), a high-resolution transmission electron microscope (HRTEM, CM200 produced by Phillips, 200kV) and a Raman spectrometer (632.8nm, Renishaw1000), carry out Characterization of the samples. The content of the metal catalyst particles and the MgO support (metal impurities) was measured using a thermogravimetric analysis device (TGA, 951TGA manufactured by Dupont Instrument). In dry air, after removing moisture from the sample at 105°C, heat to 1000°C at a speed of 5°C/min while passing dry air at a speed of 100ml/min. The so-called residual weight refers to the content of metal impurities in the sample.

(6) Results and discussion

Fig. 2 shows the Raman spectrum of the sample immediately after preparation using 100% ethanol concentration, Fig. 3 shows the Raman spectrum of the sample after reflux with nitric acid, and Fig. 4 shows the Raman spectrum of the sample after final purification . From Fig. 2, the radial-breathing mode (RBM), one of the characteristic Raman scattering modes of single-layer carbon nanotubes, can be clearly observed in the low-frequency region of 130-350 cm ^-1 . The frequency of the RBM mode is inversely proportional to the diameter of the single-walled carbon nanotube, and its relationship can be expressed as ω=223.75/d+6.5 (for example, refer to Lyu, SC; Liu, BC; Lee, TJ; Liu, ZY; Yang, CW ; Park, CY; Lee, CJ, Chem. Commun. 2003, 734). Among them, ω is the RBM frequency in cm ^-1 , d is the diameter of single-layer carbon nanotubes in nm, and the clustering effect is taken into consideration. RBM frequencies of 130-350 cm ^-1 correspond to diameters of 0.6-1.8 nm. The shoulder at 1552 ^cm appearing on the left side of the main peak (G band) at 1586 ^cm originates from the splitting of the E _2g mode of graphite. And, this shoulder peak is also one of characteristic Raman scattering mode of single wall carbon nanotube (for example, with reference to A.Kasuya, Y.Sasaki, Y.Saito, K.Tohji, Y.Nishina, Phys.Rev.Lett.1997 , 78, 4434). In addition to these characteristic peaks, a defect-induced mode, the so-called D band, appears at 1320 cm ^-1 , which indicates that the sample contains defective carbon such as amorphous carbon. The intensity ratio of the G band to the D band (G/D ratio) was 2.8. The G/D ratio is a measure of the purity of single-walled carbon nanotubes, and the ratio increases with the purity of single-walled carbon nanotubes (for example, referring to H.Kataura, Y.Kumazawa, Y.Maniwa, Y. Ohtsuka, R. Sen, S. Suzuki, Y. Achiba, Carbon 2000, 38, 1691).

A fibrous product was observed in the scanning electron microscope (SEM) image of the sample immediately after preparation (Fig. 5a), which is considered to be a bundle of single-walled carbon nanotubes containing impurities such as amorphous carbon and metal particles. . Thermogravimetric measurements showed a metal impurity content of 54% by weight in the sample as prepared.

Figure 5b, Figure 5c, and Figure 5d show the SEM images of the samples, Figure 5b shows the sample after HCl treatment, Figure 5c shows the sample after HNO ₃ reflux, and Figure 5d shows the final refined sample. As samples for purification, the present inventors used samples prepared at 100% ethanol concentration. After HCl treatment, many bundles containing a large amount of amorphous carbon were observed (Fig. 5b). The content of metal impurities was reduced from 54% to 18% by HCl treatment. In order to remove amorphous carbon and residual metal impurities, the samples after HCl treatment were refluxed in _HNO3 solution at 120 °C for 12 hours. The reflowed sample consisted mainly of large-diameter bundles (Fig. 5c), and the content of metallic impurities was reduced to 8%. The Raman spectroscopic results of the reflowed sample showed a D band with significant intensity ( FIG. 3 ). The inventors believe that this D-band originates from small pieces of amorphous carbon that are prepared and coated on single-layer carbon nanotube bundles during reflux in HNO ₃ . In order to completely remove residual impurities, the refluxed sample was subjected to heat treatment at 470° C. and HCl treatment in air. The SEM image of the final refined sample showed almost no impurities (Fig. 5d).

Fig. 6 shows a transmission electron microscope (TEM) image of the final refined sample, (a) is a low magnification, (b) is a high magnification. The sample basically consisted of bundles of single-walled carbon nanotubes with few impurities present. The Raman spectrum of the final refined sample showed a D band of negligible intensity (Figure 4), and showed that most of the amorphous carbon was removed in the final refining process. The G/D ratio increased from 2.8 to 100 or more by refining the composition of the present inventors.

In order to confirm the purity of the single-walled carbon nanotubes in the sample, thermogravimetric analysis was performed. The results are shown in FIGS. 7 to 10 . Fig. 7 shows the measurement results of the sample just after preparation, Fig. 8 shows the measurement results of the sample after HCl treatment, Fig. 9 shows the measurement results of the sample after HNO _reflux , and Fig. 10 shows the measurement results of the final refined sample . As shown in FIG. 10 , the residual weight of the final refined sample was 2% by weight or less. In the weight change rate (-dw/dT) analysis, only one peak with a maximum value around 585°C was obtained, indicating that the sample contained a combustible component. The temperature of this maximum is consistent with the reported combustion temperature of single-walled carbon nanotubes, which suggests that the final refined sample is composed of single-walled carbon nanotubes with a purity of 98%. This suggestion was confirmed by TEM observation (Fig. 6).

In this example, the diameter and chirality of single-walled carbon nanotubes are determined by the formation reaction in the presence of a catalyst. Therefore, the present inventors hypothesized that the structure of single-walled carbon nanotubes can be controlled by the ethanol supply rate. To test this hypothesis, single-layer carbon nanotubes were prepared with different ethanol concentrations. Table 1 summarizes the ethanol concentrations tested and the results obtained. The distribution of diameters is judged by the RBM frequency in the Raman spectrum. In addition, the results of Table 1 are shown graphically in FIG. 11 .

Table 1

ethanol concentration Distribution of diameters (nm) Ethanol (100%) ethanol: H ₂ O = 4: 1 (80%) ethanol: H ₂ O = 3: 1 (75%) ethanol: H ₂ O = 2: 1 (67%) ethanol: H ₂ O = 1:1 (50%) 0.6-1.8(Δ1.2)0.7-1.6(Δ0.9)0.8-1.4(Δ0.6)0.8-1.5(Δ0.7)0.7-1.5(Δ0.8)

As shown in Fig. 11, the concentration of ethanol significantly affects the diameter distribution of single-walled carbon nanotubes. In general, if the ethanol concentration is high, the ethanol vapor concentration is correspondingly high, causing many kinds of carbon attachment based on the vapor-liquid-solid (VLS) growth process of carbon nanotubes. On the other hand, when the ethanol concentration is low, the ethanol vapor concentration is also reduced accordingly, and the types of carbon deposition types are reduced. This trend can be seen in Figure 11.

The production of high-quality single-walled carbon nanotubes greatly depends on the experimental settings such as the shape of the reaction site of the CVD apparatus. In conventional ethanol CVD, single-walled carbon nanotubes are produced under reduced pressure in order to prevent liquefaction of evaporated ethanol. Under reduced pressure, it is more difficult to control growth parameters such as ethanol concentration than under normal pressure. In the CVD apparatus shown in Figure 1, the inside of one end of the quartz tube 11 that is positioned at the outside of furnace 12 is provided with the container 16 that adds ethanol or ethanol aqueous solution 15, therefore, by adjusting ethanol concentration and gasification rate, can be in High-quality single-walled carbon nanotubes were prepared with controlled diameter distribution under normal pressure.

As described above, using the CVD apparatus designed by the present inventors, high-quality single-walled carbon nanotubes can be produced from ethanol or an aqueous ethanol solution under normal pressure. The mass and diameter distribution of single-layer carbon nanotubes can be controlled by adjusting the ethanol concentration and gasification rate. Single-walled carbon nanotubes with a purity of 98% can be prepared by combining HCl treatment, nitric acid reflux, and air oxidation for compositional refinement.

One embodiment and one example of the present invention have been specifically described above, but the present invention is not limited to the above-mentioned embodiment and example, and various changes can be made according to the technical solutions of the present invention.

For example, the structure, numerical value, material, raw material, process, etc. of the CVD apparatus listed in the above-mentioned embodiments and examples are only examples after all, and the structure, numerical value, material, raw material, etc. of the CVD apparatus different from these may be used as needed. process etc.

A brief description of the symbols in the drawings is as follows:

11: Quartz tube

12: Furnace

13: Thermocouple

14: Temperature control device

15: Ethanol or ethanol aqueous solution

16: container

17: Quartz Boat

18: Catalyst

19: Iron sheet

20: magnet

Claims (12)

1. A preparation method for single-layer carbon nanotubes, characterized in that, using the gas obtained by vaporizing alcohol or an aqueous solution of alcohol as reaction gas, utilizing chemical vapor deposition, making single-layer carbon nanotubes under normal pressure grow. 2. The preparation method of single-walled carbon nanotubes according to claim 1, characterized in that, the gas is obtained by vaporizing the above-mentioned alcohol or an aqueous solution of alcohol outside the reaction site of the chemical vapor deposition device, and the gas is introduced into the above-mentioned reaction site. 3. The method for preparing single-walled carbon nanotubes according to claim 1, characterized in that the alcohol concentration range in the aqueous solution of alcohol is greater than 0% and less than 100%. 4. The method for preparing single-walled carbon nanotubes according to claim 1, characterized in that the alcohol concentration in the aqueous solution of alcohol ranges from 50% to 95%. 5. The method for preparing single-walled carbon nanotubes according to claim 1, characterized in that the alcohol concentration in the aqueous solution of alcohol ranges from 50% to 80%. 6 . The method for preparing single-walled carbon nanotubes according to claim 1 , wherein the single-walled carbon nanotubes are grown at a growth temperature of 500° C. to 1500° C. 7 . 7 . The method for preparing single-walled carbon nanotubes according to claim 1 , wherein the single-walled carbon nanotubes are grown at a growth temperature of 650° C. to 900° C. 7 . 8. The method for preparing single-walled carbon nanotubes according to claim 1, characterized in that the above-mentioned alcohol is a monohydric alcohol. 9. the preparation method of single-layer carbon nanotube according to claim 1 is characterized in that, by regulating the alcohol concentration in the aqueous solution of above-mentioned alcohol and/or the gasification rate of the aqueous solution of above-mentioned alcohol, control above-mentioned single-layer carbon nanotube Tube diameter and/or distribution of diameters. 10. The method for producing single-walled carbon nanotubes according to claim 1, characterized in that, after the above-mentioned single-walled carbon nanotubes are grown, they are purified by acid treatment with hydrochloric acid, reflux with nitric acid, and air oxidation. . 11. A single-layer carbon nanotube, characterized in that the single-layer carbon nanotube is prepared as follows: using gas obtained by vaporizing alcohol or an aqueous solution of alcohol as a reaction gas, utilizing chemical vapor deposition, at normal pressure to grow single-walled carbon nanotubes. 12. A method for preparing an electronic component is a method for preparing an electronic component using a single-layer carbon nanotube, characterized in that, using gas obtained by vaporizing alcohol or an aqueous solution of alcohol as a reaction gas, utilizing a chemical vapor deposition method, The above-mentioned single-walled carbon nanotubes were grown under normal pressure.

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