Single chiral carbon nanotube synthesis device and use method thereof

Abstract

The invention belongs to the technical field of carbon nanotube synthesis, and particularly discloses a single chiral carbon nanotube synthesis device and a use method thereof.The synthesis device comprises a source chamber and a reaction chamber, a sample table is arranged in the reaction chamber, a substrate and a catalyst are arranged on the sample table, a medium tube is arranged in the source chamber, and a spiral line is wound around the outer side of the medium tube; one end of the medium pipe is connected with external working gas, a magnetic coil is arranged on the outer side of the source chamber, the reaction chamber is externally connected with a vapor deposition system, and the source chamber is externally connected with a high-voltage pulse generation assembly. According to the single chiral carbon nanotube synthesis device and the use method thereof, the synthesis device is convenient to operate and suitable for macro preparation, the single chiral carbon nanotube can be efficiently synthesized by accurately controlling reaction conditions, the purity reaches 95% or above, and selective synthesis of different chiral carbon nanotubes can be achieved by adjusting reaction parameters.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon nanotube synthesis, in particular to a single chiral carbon nanotube synthesis device and a use method thereof. Background Art

[0002] Carbon nanotubes are a nano-sized tubular structure material, which is formed by curling up single or multi-layer graphite sheets. They have extremely high carrier mobility and structurally adjustable band gaps, and have important application value in the fields of composite material reinforcement, nano devices, field emission and high-performance electronic devices. Moreover, due to their unique hollow structure, good conductivity, large specific surface area, and intertwined network structure, they are considered to be ideal electrode materials for high-performance lithium-ion batteries and supercapacitors, and are also the best hydrogen storage materials for hydrogen fuel cell vehicles. In recent years, they have received widespread attention in new energy storage.

[0003] Freely grown carbon nanotubes are usually a mixture of different structures and chiralities, and are prone to agglomeration and entanglement, which severely limits their application as conductive agents. Single-chirality carbon nanotubes are spiral nanostructures formed by curling up a single layer of carbon atoms, with a uniform chiral structure and unique electronic, optical and mechanical properties. Studies have shown that even small structural differences (such as different chiral angles) between different carbon nanotubes can lead to huge differences in their optical and electrical properties, and photoelectric coupling effects can also occur between carbon nanotubes with different structures. The mixture of carbon nanotubes with different structures in the growth and preparation seriously hinders their characteristic research and device application. Therefore, the large-scale preparation of single-chirality carbon nanotubes is the premise and key to building high-speed, low-power carbon-based electronic and optoelectronic devices. However, so far, the large-scale high-purity preparation and precise manipulation of single-chirality carbon nanotubes still face many challenges and have become a hot research issue in recent years.

[0004] Although the plasma enhanced chemical vapor deposition method has been widely used in the preparation of carbon nanotube materials, it lacks a control mechanism that can stably induce the chiral growth of carbon nanotubes. Recently, a low-temperature plasma with a spiral propagation was formed in a low-pressure medium tube by pulse modulation electromagnetic drive, and its spiral chirality direction changes with electromagnetic parameters. The present invention provides a carbon nanotube synthesis device, which realizes the controllable synthesis of single chiral carbon nanotubes through a specific device design and process combination. Summary of the invention

[0005] The purpose of the present invention is to provide a single chiral carbon nanotube synthesis device and a method for using the same. The synthesis device is easy to operate and suitable for large-scale preparation. By precisely controlling the reaction conditions, single chiral carbon nanotubes can be efficiently synthesized with a purity of more than 95%. By adjusting the reaction parameters, selective synthesis of carbon nanotubes with different chirality can be achieved.

[0006] To achieve the above-mentioned purpose, the present invention provides a single chiral carbon nanotube synthesis device, including a source chamber and a reaction chamber. A sample table is provided inside the reaction chamber, a substrate and a catalyst are provided on the sample table, a dielectric tube is provided inside the source chamber, a spiral wire is wound around the outside of the dielectric tube, and ring electrodes are provided at both ends of the dielectric tube, one end of the dielectric tube is connected to the external working gas, a magnetic coil is provided outside the source chamber, the reaction chamber is connected to a vapor deposition system, and the source chamber is connected to a high-voltage pulse generating component.

[0007] Preferably, the substrate material is single crystal silicon, and the catalyst is one or more of iron, cobalt, nickel, aluminum oxide, and magnesium oxide.

[0008] Preferably, the medium tube is a quartz medium tube with a length of 1 m, an inner diameter of 6 mm, and an outer diameter of 9 mm.

[0009] Preferably, one of the ring electrodes at both ends is connected to the high voltage pulse generating component, and the other is grounded.

[0010] Preferably, the working gas is argon.

[0011] Preferably, the vapor deposition system includes a gas source, a gas delivery pipe, and a nozzle. The gas delivery pipe is provided with a flow control valve. The gas source includes a carbon source gas and an auxiliary gas. The carbon source gas is one of methane and acetylene, and the auxiliary gas is one of argon and hydrogen.

[0012] The method for using the single chiral carbon nanotube synthesis device is realized by the synthesis device, and comprises the following steps: S1. Place the catalyst evenly on the base of the reaction chamber sample stage and seal the reaction chamber; S2. Turn on the vapor deposition system, adjust the flow rate of the gas source through the flow control valve of the gas delivery pipe, so that the carbon source gas and the auxiliary gas are mixed in a volume ratio of 4:1 and then sprayed into the reaction chamber through the nozzle, evacuate the medium pipe in the source chamber and introduce the working gas into the medium pipe at the same time, so that the gas pressure in the medium pipe reaches 4000Pa, and control the pressure in the reaction chamber; S3. Start the magnetic coil and adjust the magnetic field strength by applying voltage according to the requirements of the target chiral carbon nanotubes; S4. triggering a high-voltage pulse generating assembly to apply a high-voltage pulse to the reaction chamber, setting the pulse frequency, amplitude, and pulse width, and performing a growth reaction of carbon nanotubes on the catalyst surface under the synergistic effect of vapor deposition, magnetic field, and high-voltage pulses; S5. After the reaction is completed, the reaction chamber is cooled and the prepared single chiral carbon nanotubes are collected.

[0013] Preferably, in step S2, the flow rate of the carbon source gas is 105-145 ml / min, the flow rate of the auxiliary gas is 25-35 ml / min, and the pressure in the reaction chamber is controlled at 3500-4500 Pa.

[0014] Preferably, in step S3, the magnetic field strength is 80-200 mT, and the applied voltage is 3.5-3.9 kV.

[0015] Preferably, in step S4, the pulse frequency is 650-750 Hz, the amplitude is 5.5-7 kV, and the pulse width is 2-4 μs.

[0016] The advantages and beneficial effects of the present invention using the above-mentioned single chiral carbon nanotube synthesis device and its use method are: 1. The present invention can efficiently synthesize single chiral carbon nanotubes with a purity of more than 95% by precisely controlling the reaction conditions and magnetic field.

[0017] 2. The present invention can achieve the selective synthesis of carbon nanotubes with different chirality by adjusting the reaction parameters and the magnetic field strength.

[0018] 3. The synthesis device of the present invention is easy to operate and suitable for large-scale preparation.

[0019] 4. The magnetic field generated by the magnetic coil of the present invention can further control the growth direction and chirality of the carbon nanotubes, thereby improving the synthesis efficiency and purity.

[0020] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of a single chiral carbon nanotube synthesis device of the present invention; Figure 2 It is a flow chart of the use of the single chiral carbon nanotube synthesis device of the present invention.

[0022] Reference numerals 1. High-voltage pulse generating assembly; 2. Magnetic coil; 3. Spiral wire; 4. Dielectric tube; 5. Ring electrode; 6. Substrate; 7. Sample stage; 8. Gas delivery tube; 9. Carbon source gas; 10. Auxiliary gas; 11. Working gas; 12. Reaction chamber; 13. Source chamber. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0024] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0025] like Figure 1 As shown, a single chiral carbon nanotube synthesis device includes a source chamber 13 and a reaction chamber 12. A sample stage 7 is provided inside the reaction chamber 12. A substrate 6 and a catalyst (not shown in the figure) are provided on the sample stage 7. The substrate 6 is made of single crystal silicon, and the catalyst is one or more of iron, cobalt, nickel, aluminum oxide, and magnesium oxide. The source chamber 13 is connected to the reaction chamber 12.

[0026] A medium tube 4 is provided in the source chamber 13. The medium tube 4 is a quartz medium tube with a length of 1 m, an inner diameter of 6 mm, and an outer diameter of 9 mm.

[0027] A spiral wire 3 is wound around the outside of the dielectric tube 4. The existence of the spiral wire 3 can effectively modulate the three-dimensional shape of the spiral, and ring electrodes 5 are provided at both ends of the dielectric tube 4. One end of the dielectric tube 4 is connected to the external working gas 11, and the working gas 11 is argon. A magnetic coil 2 is provided outside the source chamber 13, the reaction chamber 12 is externally connected to the vapor deposition system, and the source chamber 13 is externally connected to the high-voltage pulse generating assembly 1. One of the ring electrodes 5 at both ends is connected to the high-voltage pulse generating assembly 1, and the other is grounded.

[0028] The vapor deposition system includes a gas source, a gas delivery pipe 8, and a nozzle (not shown in the figure). The gas delivery pipe 8 is provided with a flow control valve. The gas source includes a carbon source gas 9 and an auxiliary gas 10. The carbon source gas 9 is one of methane and acetylene, and the auxiliary gas 10 is one of argon and hydrogen. The vapor deposition system and the high-voltage pulse generating assembly 1 belong to the prior art.

[0029] The method for using the single chiral carbon nanotube synthesis device, such as Figure 2 As shown, the following steps are included: S1. Place the catalyst evenly on the base 6 of the sample stage 7 of the reaction chamber 12 and seal the reaction chamber 12.

[0030] S2. Turn on the vapor deposition system, adjust the flow rate of the gas source through the flow control valve of the gas delivery pipe 8, so that the carbon source gas 9 and the auxiliary gas 10 are mixed in a volume ratio of 4:1 and then sprayed into the reaction chamber 12 through the nozzle, and the medium pipe 4 in the source chamber 13 is evacuated. At the same time, the working gas 11 is introduced into the medium pipe 4 to make the air pressure in the medium pipe 4 reach 4000Pa, so as to control the pressure in the reaction chamber 12; the flow rate of the carbon source gas 9 is 105-145ml / min, the flow rate of the auxiliary gas 10 is 25-35ml / min, and the pressure in the reaction chamber is controlled at 3500-4500Pa.

[0031] S3. Start the magnetic coil 2 and adjust the magnetic field strength by applying voltage according to the requirements of the target chiral carbon nanotubes; the magnetic field strength is 80-200mT, and the applied voltage is 3.5-3.9kV. The magnetic field strength and direction are adjusted according to the number of turns of the magnetic coil 2 and the current strength. The magnetic field strength and direction have a key influence on the chirality of the carbon nanotubes.

[0032] S4. Trigger the high-voltage pulse generating component 1 to apply a high-voltage pulse into the reaction chamber, set the pulse frequency to 650-750 Hz, the amplitude to 5.5-7 kV, and the pulse width to 2-4 μs, and carry out a growth reaction of carbon nanotubes on the catalyst surface under the synergistic effect of vapor deposition, magnetic field and high-voltage pulse.

[0033] S5. After the reaction is completed, the reaction chamber is cooled and the prepared single chiral carbon nanotubes are collected.

[0034] Example 1 A method for using a single chiral carbon nanotube synthesis device comprises the following steps: S1. Place the catalyst iron evenly on the single crystal silicon substrate 6 of the sample stage 7 of the reaction chamber 12 and seal the reaction chamber 12.

[0035] S2. Turn on the vapor deposition system, adjust the flow rate of the gas source through the flow control valve of the gas delivery pipe 8, so that methane and hydrogen are mixed in a volume ratio of 4:1 and then sprayed into the reaction chamber 12 through the nozzle, evacuate the quartz medium tube in the source chamber 13 and introduce argon gas into the quartz medium tube at the same time, so that the air pressure in the medium tube 4 reaches 4000Pa, and the pressure in the reaction chamber 12 is controlled to be 3800Pa; the flow rate of methane is 145ml / min, and the flow rate of hydrogen is 30ml / min.

[0036] S3. Start the magnetic coil 2 and adjust the magnetic field strength by applying voltage according to the requirements of the target chiral carbon nanotubes; the magnetic field strength is 160mT and the applied voltage is 3.9kV. The magnetic field strength and direction are adjusted according to the number of turns and current strength of the magnetic coil 2. The magnetic field strength and direction have a key influence on the chirality of the carbon nanotubes.

[0037] S4. Trigger the high-voltage pulse generating component 1 to apply a high-voltage pulse into the reaction chamber, set the pulse frequency to 700 Hz, the amplitude to 7 kV, and the pulse width to 3 μs, and carry out a growth reaction of carbon nanotubes on the catalyst surface under the synergistic effect of vapor deposition, magnetic field and high-voltage pulse.

[0038] S5. After the reaction is completed, the reaction chamber is cooled and the prepared single chiral carbon nanotubes are collected with a purity of 97%.

[0039] Example 2 A method for using a single chiral carbon nanotube synthesis device comprises the following steps: S1. Place the catalyst cobalt evenly on the single crystal silicon substrate 6 of the sample stage 7 of the reaction chamber 12 and seal the reaction chamber 12.

[0040] S2. Turn on the vapor deposition system, adjust the flow rate of the gas source through the flow control valve of the gas delivery pipe 8, so that methane and argon are mixed in a volume ratio of 4:1 and then sprayed into the reaction chamber 12 through the nozzle, evacuate the quartz medium tube in the source chamber 13 and introduce argon into the quartz medium tube at the same time, so that the air pressure in the medium tube 4 reaches 4000Pa, and the pressure in the reaction chamber 12 is controlled to be 4000Pa; the flow rate of methane is 105ml / min, and the flow rate of argon is 30ml / min.

[0041] S3. Start the magnetic coil 2 and adjust the magnetic field strength by applying voltage according to the requirements of the target chiral carbon nanotubes; the magnetic field strength is 80mT and the applied voltage is 3.5kV. The magnetic field strength and direction are adjusted according to the number of turns and current strength of the magnetic coil 2. The magnetic field strength and direction have a key influence on the chirality of the carbon nanotubes.

[0042] S4. Trigger the high-voltage pulse generating component 1 to apply a high-voltage pulse into the reaction chamber, set the pulse frequency to 700 Hz, the amplitude to 6 kV, and the pulse width to 3 μs, and carry out a growth reaction of carbon nanotubes on the catalyst surface under the synergistic effect of vapor deposition, magnetic field and high-voltage pulse.

[0043] S5. After the reaction is completed, the reaction chamber is cooled and the prepared single chiral carbon nanotubes are collected with a purity of 95%.

[0044] The intensity and direction of the magnetic field have a key influence on the chirality of carbon nanotubes. When the magnetic field intensity is in a lower range, such as less than 80mT, the growth of carbon nanotubes is mainly dominated by vapor deposition and other factors, and the chirality distribution is relatively random; as the magnetic field intensity gradually increases to the 80-200mT range, the nucleation rate of carbon nanotubes of a specific chirality will gradually increase. This is because the magnetic field will change the electron cloud distribution and atomic magnetic moment in the reaction system, thereby affecting the adsorption and decomposition process of the carbon source molecules on the catalyst surface, and promoting the formation of carbon nanotube precursors with a specific chiral structure. For the direction of the magnetic field, the magnetic field along the axial direction of the reaction chamber 12 and the magnetic field perpendicular to the axial direction will induce the growth of carbon nanotubes of different chirality. For example, when the magnetic field is along the axial direction, it is conducive to the formation of carbon nanotubes with a chiral angle of 0-30 degrees; when the magnetic field is perpendicular to the axial direction, it is easier to generate carbon nanotubes with a chiral angle of 20-30 degrees. By accurately controlling the current size and direction of the magnetic coil 2, a magnetic field of appropriate intensity and direction is generated.

[0045] In the low-pressure medium tube 4, a low-temperature plasma propagating in a spiral form is formed by pulse modulation electromagnetic drive, and the direction of the spiral chirality changes with the electromagnetic parameters. Under given parameters, the plasma discharge mode is a spiral wave discharge mode, and under given CH4 flow rate, the electron energy distribution in the plasma is sufficient to dissociate methane molecules and form carbon-containing active free radicals. By adjusting the CH4 flow rate, the preparation of different carbon-based films is achieved.

[0046] Therefore, the present invention adopts the above-mentioned single chiral carbon nanotube synthesis device and its use method. The synthesis device is easy to operate and suitable for large-scale preparation. By precisely controlling the reaction conditions, single chiral carbon nanotubes can be efficiently synthesized with a purity of more than 95%. By adjusting the reaction parameters, selective synthesis of carbon nanotubes with different chirality can be achieved.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A single chiral carbon nanotube synthesis device, characterized in that: It includes a source chamber and a reaction chamber. A sample table is arranged inside the reaction chamber, a substrate and a catalyst are arranged on the sample table, a medium tube is arranged inside the source chamber, a spiral wire is wound around the outside of the medium tube, and ring electrodes are arranged at both ends of the medium tube. One end of the medium tube is connected to the external working gas, a magnetic coil is arranged outside the source chamber, the reaction chamber is connected to a vapor deposition system, and the source chamber is connected to a high-voltage pulse generating component.

2. The single chiral carbon nanotube synthesis device according to claim 1, characterized in that: The substrate material is single crystal silicon, and the catalyst is one or more of iron, cobalt, nickel, aluminum oxide, and magnesium oxide.

3. The single chiral carbon nanotube synthesis device according to claim 1, characterized in that: The medium tube is a quartz medium tube with a length of 1 m, an inner diameter of 6 mm, and an outer diameter of 9 mm.

4. The single chiral carbon nanotube synthesis device according to claim 1, characterized in that: One of the ring electrodes at both ends is connected to the high voltage pulse generating component, and the other is grounded.

5. The single chiral carbon nanotube synthesis device according to claim 1, characterized in that: The working gas is argon.

6. The single chiral carbon nanotube synthesis device according to claim 1, characterized in that: The vapor deposition system includes a gas source, a gas delivery pipe, and a nozzle. The gas delivery pipe is provided with a flow control valve. The gas source includes a carbon source gas and an auxiliary gas. The carbon source gas is one of methane and acetylene, and the auxiliary gas is one of argon and hydrogen.

7. A method for using a single chiral carbon nanotube synthesis device, characterized in that: The method is implemented by a synthesis device according to any one of claims 1 to 6, comprising the following steps: S1. Place the catalyst evenly on the base of the reaction chamber sample stage and seal the reaction chamber; S2. Turn on the vapor deposition system, adjust the flow rate of the gas source through the flow control valve of the gas delivery pipe, so that the carbon source gas and the auxiliary gas are mixed in a volume ratio of 4:1 and then sprayed into the reaction chamber through the nozzle, evacuate the medium pipe in the source chamber and introduce the working gas into the medium pipe at the same time, so that the gas pressure in the medium pipe reaches 4000Pa, and control the pressure in the reaction chamber; S3. Start the magnetic coil and adjust the magnetic field strength by applying voltage according to the requirements of the target chiral carbon nanotubes; S4. triggering a high-voltage pulse generating assembly to apply a high-voltage pulse to the reaction chamber, setting the pulse frequency, amplitude, and pulse width, and performing a growth reaction of carbon nanotubes on the catalyst surface under the synergistic effect of vapor deposition, magnetic field, and high-voltage pulses; S5. After the reaction is completed, the reaction chamber is cooled and the prepared single chiral carbon nanotubes are collected.

8. The method for using the single chiral carbon nanotube synthesis device according to claim 7, characterized in that: In step S2, the flow rate of the carbon source gas is 105-145 ml / min, the flow rate of the auxiliary gas is 25-35 ml / min, and the pressure in the reaction chamber is controlled at 3500-4500 Pa.

9. The method for using the single chiral carbon nanotube synthesis device according to claim 7, characterized in that: In step S3, the magnetic field strength is 80-200 mT, and the applied voltage is 3.5-3.9 kV.

10. The method for using the single chiral carbon nanotube synthesis device according to claim 7, characterized in that: In step S4, the pulse frequency is 650-750 Hz, the amplitude is 5.5-7 kV, and the pulse width is 2-4 μs.

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