Method for regulating and controlling diameter of single-walled carbon nanotube prepared by arc discharge

Abstract

The invention relates to a method for regulating and controlling the diameter of a single-walled carbon nanotube prepared by arc discharge, and belongs to the technical field of carbon nanotube preparation, the method comprises the following steps: preparing an anode comprising a metal catalyst, a carbon raw material and a component A without catalytic activity, and placing the anode and a pure graphite rod cathode in an electric arc furnace; and introducing a set atmosphere into the electric arc furnace, conducting the cathode and the anode under a set current, pulling the cathode and the anode open to maintain arc discharge, continuously consuming the anode under the action of the arc, and collecting the generated gray black carbon nanotube product on the furnace wall. According to the method provided by the invention, a component without catalytic activity is introduced to serve as a nucleation site, a dispersed phase and a surface property regulating agent in the gas phase nucleation process of the metal catalyst, so that the situation that the size is too large due to agglomeration in the forming process of the metal catalyst can be avoided, and the size and the structure of metal catalyst particles are effectively regulated; furthermore, the diameter distribution of the obtained single-walled carbon nanotube can be effectively regulated and controlled, and the diameter of the prepared single-walled carbon nanotube is reduced.

Description

Technical Field

[0001] This invention relates to the field of carbon nanotube preparation technology, and in particular to a method for controlling the diameter of single-walled carbon nanotubes prepared by arc discharge. Background Technology

[0002] The structure of single-walled carbon nanotubes (SWCNTs) uniquely determines their physical and chemical properties. Based on their conductivity, SWCNTs can be divided into metallic and semiconducting SWCNTs. For semiconducting SWCNTs, their band gap is negatively correlated with their diameter. SWCNTs, with their excellent electrical, thermal, and mechanical properties, especially their extremely high electron and hole mobility, are the core materials for constructing next-generation carbon-based nanoelectronic devices. However, in order to reduce the device performance fluctuations caused by the band gap differences of carbon nanotubes, high-end electronic devices require SWCNT samples to have a narrow diameter distribution, which poses a severe challenge to the controllable synthesis of SWCNTs.

[0003] There are three main methods for synthesizing single-walled carbon nanotubes: electric arc method, laser method, and chemical vapor deposition method. Among them, the electric arc method is the earliest used and has the highest yield. In order to obtain single-walled carbon nanotubes, a certain proportion of metal catalyst needs to be used in the anode. When the cathode and anode are brought into contact and pulled apart under the influence of electricity, an electric arc can be generated.

[0004] In existing technologies, the diameter of single-walled carbon nanotubes obtained by arc discharge is typically distributed in the range of 1.2-1.7 nm, which is too large and too wide for high-end electronic devices. Summary of the Invention

[0005] The present invention aims to provide a method for controlling the diameter of single-walled carbon nanotubes obtained by arc discharge, so as to overcome the shortcomings of the prior art. The technical problem to be solved by the present invention is achieved through the following technical solution.

[0006] The method for controlling the diameter of single-walled carbon nanotubes prepared by arc discharge provided by the present invention includes:

[0007] An anode comprising a metal catalyst, a carbon raw material, and a component A without catalytic activity is prepared, and the anode and a pure graphite rod cathode are placed in an electric arc furnace. The component A without catalytic activity is selected from one or more of the following: elemental boron, boron oxide, magnesium oxide, aluminum oxide, calcium oxide, gallium oxide, indium oxide, strontium oxide, barium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, gallium hydroxide, indium hydroxide, strontium hydroxide, barium hydroxide, salts containing boron, salts containing magnesium, salts containing aluminum, salts containing calcium, salts containing gallium, salts containing indium, salts containing strontium, and salts containing barium.

[0008] A set atmosphere is introduced into the electric arc furnace, the cathode and anode are brought into contact and a set current is passed through. After conduction, the distance between the cathode and anode is increased to maintain the electric arc discharge. Under the action of the electric arc, the anode is continuously consumed, and the generated gray-black carbon nanotube products are collected on the furnace wall.

[0009] In the above scheme, the non-catalytically active component A is one or more of the following: magnesium oxide, calcium oxide, strontium oxide, barium oxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, salt containing magnesium, salt containing calcium, salt containing strontium, and salt containing barium.

[0010] In the above scheme, the non-catalytically active component A is sodium borate, magnesium oxide, magnesium carbonate, aluminum hydroxide, calcium sulfate, strontium chloride, or barium carbonate.

[0011] In the above scheme, the metal catalyst is one or more of the following: scandium, iron, cobalt, nickel, yttrium, molybdenum, tungsten, scandium oxide, iron oxide, cobalt oxide, nickel oxide, yttrium oxide, molybdenum oxide, tungsten oxide, scandium sulfide, iron sulfide, cobalt sulfide, nickel sulfide, yttrium sulfide, molybdenum sulfide, and tungsten sulfide.

[0012] In the above scheme, the metal catalyst is selected from two or three of the following: elemental iron, elemental cobalt, elemental nickel, elemental yttrium, iron oxide, cobalt oxide, nickel oxide, yttrium oxide, iron sulfide, cobalt sulfide, nickel sulfide, and yttrium sulfide.

[0013] In the above scheme, the amount of component A without catalytic activity is 0-100 times that of the metal catalyst, and the amount of component A without catalytic activity is 0-5 times that of the carbon raw material.

[0014] In the above scheme, the atmosphere introduced into the electric arc furnace is one or two of hydrogen, helium, nitrogen, and argon.

[0015] In the above scheme, the total pressure in the electric arc furnace is 30kPa-100kPa before the cathode and anode are brought into contact.

[0016] In the above scheme, the distance between the cathode and the anode is 1mm-20mm during the arc discharge process.

[0017] In the above scheme, the arc discharge current is 40-80A and the arc discharge voltage is 15-50V.

[0018] The embodiments of the present invention have the following advantages:

[0019] The method for controlling the diameter of single-walled carbon nanotubes obtained by arc discharge provided in this invention introduces a component without catalytic activity as a nucleation site, dispersed phase, and surface property regulator during the gas-phase nucleation process of a metal catalyst. This avoids the agglomeration of the metal catalyst during its formation, resulting in excessively large sizes. It effectively controls the size and structure of the metal catalyst particles, thereby effectively controlling the diameter distribution of the obtained single-walled carbon nanotubes and reducing their diameter. This method is simple, easy to operate, and low in cost, making it suitable for large-scale industrial production. The obtained single-walled carbon nanotubes are of high quality, with small diameters and narrow distributions, making them suitable as materials for various electronic devices such as field-effect transistors. Attached Figure Description

[0020] Figure 1 This is a step diagram of a method for controlling the diameter of single-walled carbon nanotubes obtained by arc discharge according to the present invention;

[0021] Figure 2 This is a scanning electron microscope image of the carbon nanotubes prepared in the first embodiment of the present invention;

[0022] Figure 3 This is a scanning electron microscope image of the carbon nanotubes prepared in the first comparative example of the present invention.

[0023] Figure 4(a) is a transmission electron microscope image of the carbon nanotubes prepared in the sixth embodiment of the present invention;

[0024] Figure 4(b) is a statistical diagram of pipe diameter distribution corresponding to the sixth embodiment of the present invention;

[0025] Figure 5(a) is a transmission electron microscope image of the carbon nanotubes prepared in the second comparative example of the present invention.

[0026] Figure 5(b) is a statistical diagram of pipe diameter distribution corresponding to the second comparative example of the present invention;

[0027] Figure 6 These are the Raman spectra of the carbon nanotubes prepared in the first embodiment and the first comparative example of the present invention at a wavelength of 785 nm.

[0028] Figure 7 These are the Raman spectra of the carbon nanotubes prepared in the second embodiment and the first comparative embodiment of the present invention at a wavelength of 785 nm.

[0029] Figure 8 This is the Raman spectrum of the carbon nanotubes prepared in the third embodiment and the second comparative embodiment of the present invention at a wavelength of 785 nm.

[0030] Figure 9 These are the Raman spectra of the carbon nanotubes prepared in the fourth embodiment and the third comparative embodiment of the present invention at a wavelength of 785 nm.

[0031] Figure 10 These are the Raman spectra of the carbon nanotubes prepared in the fifth embodiment and the third comparative embodiment of the present invention at a wavelength of 785 nm.

[0032] Figure 11 These are the Raman spectra of the carbon nanotubes prepared in the sixth embodiment and the first comparative example of the present invention at a wavelength of 785 nm.

[0033] Figure 12 These are the Raman spectra of the carbon nanotubes prepared in the seventh embodiment and the first comparative example of the present invention at a wavelength of 785 nm.

[0034] Figure 13 These are the Raman spectra of the carbon nanotubes prepared in the eighth embodiment and the first comparative example of the present invention at a wavelength of 785 nm.

[0035] Figure 14 These are the Raman spectra of the carbon nanotubes prepared in the ninth embodiment and the first comparative example of the present invention at a wavelength of 785 nm.

[0036] Figure 15 These are the Raman spectra of the carbon nanotubes prepared in the tenth embodiment and the first comparative example of the present invention at a wavelength of 785 nm.

[0037] Figure 16 These are the baseline-subtracted and normalized absorption spectra of the carbon nanotubes prepared in the first embodiment and the first comparative example of the present invention.

[0038] Figure 17 These are the baseline-reduced and normalized absorption spectra of the carbon nanotubes prepared in the second embodiment and the first comparative example of the present invention.

[0039] Figure 18 This is the absorption spectrum of the carbon nanotubes prepared in the third embodiment and the second comparative example of the present invention after baseline subtraction and normalization.

[0040] Figure 19 These are the baseline-reduced and normalized absorption spectra of the carbon nanotubes prepared in the fifth embodiment and the first comparative example of the present invention.

[0041] Figure 20 This is the absorption spectrum of the carbon nanotubes prepared in the sixth embodiment and the second comparative example of the present invention after baseline subtraction and normalization.

[0042] Figure 21 These are the baseline-reduced and normalized absorption spectra of the carbon nanotubes prepared in the seventh embodiment and the first comparative example of the present invention.

[0043] Figure 22These are the baseline-reduced and normalized absorption spectra of the carbon nanotubes prepared in the eighth embodiment and the first comparative example of the present invention.

[0044] Figure 23 These are the baseline-subtracted and normalized absorption spectra of the carbon nanotubes prepared in the ninth embodiment and the first comparative example of the present invention.

[0045] Figure 24 These are the baseline-subtracted and normalized absorption spectra of the carbon nanotubes prepared in the tenth embodiment and the first comparative example of the present invention. Detailed Implementation

[0046] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0047] like Figure 1 As shown, this invention provides a method for controlling the diameter of single-walled carbon nanotubes obtained by arc discharge, the method comprising the following steps:

[0048] Step S1: Prepare an anode comprising a metal catalyst, carbon raw material and component A which has no catalytic activity, and place the anode and a pure graphite rod cathode in an electric arc furnace;

[0049] Specifically, the metal catalyst is selected from elemental scandium, elemental chromium, elemental iron, elemental cobalt, elemental nickel, elemental copper, elemental zinc, elemental yttrium, elemental zirconium, elemental molybdenum, elemental ruthenium, elemental rhodium, elemental palladium, elemental lanthanum, elemental cerium, elemental tungsten, elemental rhenium, elemental osmium, elemental iridium, oxides of scandium, oxides of chromium, oxides of iron, oxides of cobalt, oxides of nickel, oxides of copper, oxides of zinc, oxides of yttrium, oxides of zirconium, oxides of molybdenum, oxides of ruthenium, oxides of rhodium, oxides of palladium, oxides of lanthanum, oxides of cerium, oxides of tungsten, oxides of rhenium, oxides of osmium, oxides of iridium, sulfides of scandium, sulfides of chromium, sulfides of iron, sulfides of cobalt, sulfides of nickel, sulfides of copper, sulfides of zinc, sulfides of yttrium, sulfides of zirconium, and sulfides of molybdenum. The composition includes one or more of the following: ruthenium sulfides, rhodium sulfides, palladium sulfides, lanthanum sulfides, cerium sulfides, tungsten sulfides, rhenium sulfides, osmium sulfides, and iridium sulfides; preferably, elemental scandium, elemental iron, elemental cobalt, elemental nickel, elemental yttrium, elemental molybdenum, elemental tungsten, oxides of scandium, oxides of iron, oxides of cobalt, oxides of nickel, oxides of yttrium, and oxides of molybdenum. One or more of tungsten oxides, scandium sulfides, iron sulfides, cobalt sulfides, nickel sulfides, yttrium sulfides, molybdenum sulfides, and tungsten sulfides, more preferably two or three of elemental iron, elemental cobalt, elemental nickel, elemental yttrium, iron oxides, cobalt oxides, nickel oxides, yttrium oxides, iron sulfides, cobalt sulfides, nickel sulfides, and yttrium sulfides;

[0050] Specifically, the carbon raw material can be selected from one or more of graphite, coal, carbon black, coke, activated carbon, amorphous carbon, and biomass carbon, preferably one or two of graphite, coal, and carbon black, and more preferably graphite.

[0051] Specifically, the non-catalytically active component A can be selected from one or more of elemental boron, boron oxides, or salts containing boron.

[0052] Specifically, the non-catalytically active component A may also be selected from one or more of the following: magnesium oxide, aluminum oxide, calcium oxide, gallium oxide, indium oxide, strontium oxide, barium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, gallium hydroxide, indium hydroxide, strontium hydroxide, barium hydroxide, salts containing magnesium, salts containing aluminum, salts containing calcium, salts containing gallium, salts containing indium, salts containing strontium, and salts containing barium.

[0053] Specifically, the non-catalytically active component A is preferably one or more of the following: elemental boron, boron oxide, salt containing boron, magnesium oxide, aluminum oxide, calcium oxide, strontium oxide, barium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, salt containing magnesium, salt containing aluminum, salt containing calcium, salt containing strontium, and salt containing barium; more preferably, it is one or more of the following: magnesium oxide, calcium oxide, strontium oxide, barium oxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, salt containing magnesium, salt containing calcium, salt containing strontium, and salt containing barium.

[0054] Specifically, the amount of component A, which has no catalytic activity, is 0-1000 times that of the metal catalyst, preferably 0.1-100 times, and more preferably 1-10 times.

[0055] Specifically, the amount of component A, which has no catalytic activity, is 0-100 times that of the carbon raw material, preferably 0-5 times, and more preferably 0-0.5 times.

[0056] Specifically, by introducing a component A that has no catalytic activity as a nucleation site, dispersed phase and surface property regulator in the gas-phase nucleation process of metal catalysts, the metal catalysts can be prevented from agglomerating and becoming too large during the formation process, effectively controlling the size and structure of the metal catalyst particles, and thus effectively controlling the diameter distribution of the obtained single-walled carbon nanotubes.

[0057] Step S2: Introduce the set atmosphere into the electric arc furnace, bring the cathode and anode into contact and allow the set current to pass through. After conduction, increase the distance between the cathode and anode to maintain the electric arc discharge. Under the action of the electric arc, the anode is continuously consumed, and the generated gray-black carbon nanotube products are collected on the furnace wall.

[0058] Specifically, the atmosphere introduced into the electric arc furnace is one or more of hydrogen, helium, nitrogen, argon, methane, carbon monoxide, air, water, methanol, and ethanol, preferably one or more of hydrogen, helium, nitrogen, argon, carbon monoxide, and air, and more preferably one or two of hydrogen, helium, nitrogen, and argon.

[0059] Specifically, before the cathode and anode come into contact, the total pressure in the electric arc furnace is 2 kPa-1000 kPa, preferably 10 kPa-200 kPa, and more preferably 30 kPa-100 kPa;

[0060] Specifically, the circuit is made to be connected by bringing the cathode and anode into contact, and then the cathode and anode are pulled apart to generate a discharge arc;

[0061] Specifically, the current of the arc discharge is 30-150A, preferably 35-110A, and more preferably 40-80A;

[0062] Specifically, the voltage of the electric arc discharge is 15-50V;

[0063] Specifically, during the arc discharge process, the distance between the cathode and the anode is set to be 1mm-20mm;

[0064] Specifically, during the arc discharge process, the area near the arc core contains component A, which has no catalytic activity, or its reaction products;

[0065] Specifically, under the action of the electric arc, the anode is continuously consumed, while the non-catalytically active component A, the metal catalyst, and carbon are evaporated.

[0066] In the first embodiment of the present invention, a density of 1.85 g·cm³ is used. -3 A perforated graphite rod with an outer diameter of 6 mm, an inner diameter of 4 mm, a hole depth of 40 mm, and a total length of 60 mm was made from graphite. A mixed powder with a weight ratio of graphite:nickel:cobalt:ferrous sulfide:sodium borate = 5:6:6:1:30 was prepared and filled into the perforated graphite rod to prepare the anode. In the consumable part of the anode, the amount of sodium borate was 0.058 times the amount of graphite, and the amount of sodium borate was 1.46 times the total amount of nickel, cobalt, and ferrous sulfide. A pure graphite rod with a diameter of 8 mm was used as the cathode. The two electrodes were placed horizontally opposite each other. The electric arc furnace cavity was evacuated to below 20 Pa, and helium gas was introduced at 30 kPa. This process was repeated three times. The cathode and anode were brought into contact. The DC welding arc power supply was turned on, the distance between the cathode and anode was adjusted to 8 mm, the discharge current was adjusted to 60 A, and the arc discharge lasted for about 5 minutes. The generated gray-black carbon nanotube products were collected on the furnace wall.

[0067] The carbon nanotubes prepared in the first embodiment were tested using a scanning electron microscope, and the images are as follows. Figure 2 As shown, by Figure 2 It can be seen that the introduction of sodium borate can grow single-walled carbon nanotubes;

[0068] In the second embodiment of the present invention, a density of 1.85 g·cm³ is used. -3A perforated graphite rod with an outer diameter of 6 mm, an inner diameter of 4 mm, a hole depth of 40 mm, and a total length of 60 mm was made from graphite. A mixed powder with a weight ratio of graphite:nickel:cobalt:ferrous sulfide:magnesium oxide = 5:6:6:1:30 was prepared and filled into the perforated graphite rod to prepare the anode. At this time, in the consumable part of the anode, the amount of magnesium oxide used was 0.118 times the amount of graphite used, and the amount of magnesium oxide used was 3.48 times the total amount of nickel, cobalt, and ferrous sulfide used. A pure graphite rod with a diameter of 8 mm was used as the cathode. The two electrodes were placed horizontally opposite each other. The electric arc furnace cavity was evacuated to below 20 Pa, and helium gas was introduced at 30 kPa. This was repeated three times. The cathode and anode were brought into contact. The DC welding arc power supply was turned on. The distance between the cathode and anode was adjusted to 8 mm, and the discharge current was adjusted to 60 A. The arc discharge lasted for about 5 minutes. The gray-black carbon nanotube products generated were collected on the furnace wall.

[0069] In the third embodiment of the present invention, a density of 1.85 g·cm³ is used. -3 A perforated graphite rod with an outer diameter of 6 mm, an inner diameter of 4 mm, a hole depth of 40 mm, and a total length of 60 mm was made from graphite. A mixed powder with a weight ratio of graphite:nickel:cobalt:magnesium oxide = 5:6:6:30 was prepared and filled into the perforated graphite rod to prepare the anode. At this time, in the consumable part of the anode, the amount of magnesium oxide used was 0.120 times the amount of graphite used, and the amount of magnesium oxide used was 3.67 times the total amount of nickel and cobalt used. A pure graphite rod with a diameter of 8 mm was used as the cathode. The two electrodes were placed horizontally opposite each other. The electric arc furnace cavity was evacuated to below 20 Pa, and helium gas was introduced at 30 kPa. This was repeated three times. The cathode and anode were brought into contact. The DC welding arc power supply was turned on. The distance between the cathode and anode was adjusted to 8 mm, and the discharge current was adjusted to 60 A. The arc discharge lasted for about 5 minutes. The gray-black carbon nanotube products generated were collected on the furnace wall.

[0070] In the fourth embodiment of the present invention, a density of 1.85 g·cm³ is used. -3 A perforated graphite rod with an outer diameter of 6 mm, an inner diameter of 4 mm, a hole depth of 40 mm, and a total length of 60 mm was made from graphite. A mixed powder with a weight ratio of graphite:nickel:magnesium oxide = 5:12:30 was prepared and filled into the perforated graphite rod to prepare the anode. At this time, in the consumable part of the anode, the amount of magnesium oxide was 0.121 times that of graphite and the amount of magnesium oxide was 3.68 times that of nickel. A pure graphite rod with a diameter of 8 mm was used as the cathode. The two electrodes were placed horizontally opposite each other. The electric arc furnace cavity was evacuated to below 20 Pa, and helium gas was introduced at 30 kPa. This was repeated three times. The cathode and anode were brought into contact. The DC welding arc power supply was turned on. The distance between the cathode and anode was adjusted to 8 mm. The discharge current was adjusted to 60 A. The arc discharge lasted for about 5 minutes. The gray-black carbon nanotube products generated were collected on the furnace wall.

[0071] In the fifth embodiment of the present invention, a density of 1.85 g·cm³ is used.-3 A perforated graphite rod with an outer diameter of 6 mm, an inner diameter of 4 mm, a hole depth of 40 mm, and a total length of 60 mm was made from graphite. A mixed powder with a weight ratio of graphite:nickel:cobalt:ferrous sulfide:magnesium carbonate = 5:6:6:1:30 was prepared and filled into the perforated graphite rod to prepare the anode. At this time, in the consumable part of the anode, the amount of magnesium carbonate used was 0.058 times the amount of graphite used, and the amount of magnesium carbonate used was 1.66 times the total amount of nickel, cobalt, and ferrous sulfide used. A pure graphite rod with a diameter of 8 mm was used as the cathode. The two electrodes were placed horizontally opposite each other. The electric arc furnace cavity was evacuated to below 20 Pa, and helium gas was introduced at 30 kPa. This was repeated three times. The cathode and anode were brought into contact. The DC welding arc power supply was turned on. The distance between the cathode and anode was adjusted to 8 mm, and the discharge current was adjusted to 60 A. The arc discharge lasted for about 5 minutes. The gray-black carbon nanotube products generated were collected on the furnace wall.

[0072] In the sixth embodiment of the present invention, a density of 1.85 g·cm³ is used. -3 A perforated graphite rod with an outer diameter of 6 mm, an inner diameter of 4 mm, a hole depth of 40 mm, and a total length of 60 mm was made from graphite. A mixed powder with a weight ratio of graphite:nickel:cobalt:magnesium oxide = 5:6:6:30 was prepared and filled into the perforated graphite rod to prepare the anode. At this time, in the consumable part of the anode, the amount of magnesium carbonate used was 0.059 times the amount of graphite used, and the amount of magnesium carbonate used was 1.75 times the total amount of nickel and cobalt used. A pure graphite rod with a diameter of 8 mm was used as the cathode. The two electrodes were placed horizontally opposite each other. The electric arc furnace cavity was evacuated to below 20 Pa, and helium gas was introduced at 30 kPa. This was repeated three times. The cathode and anode were brought into contact. The DC welding arc power supply was turned on. The distance between the cathode and anode was adjusted to 8 mm, and the discharge current was adjusted to 60 A. The arc discharge lasted for about 5 minutes. The gray-black carbon nanotube products generated were collected on the furnace wall.

[0073] In the seventh embodiment of the present invention, a density of 1.85 g·cm³ is used. -3 A perforated graphite rod with an outer diameter of 6 mm, an inner diameter of 4 mm, a hole depth of 40 mm, and a total length of 60 mm was made from graphite. A mixed powder with a weight ratio of graphite:nickel:cobalt:ferrous sulfide:aluminum hydroxide = 5:6:6:1:30 was prepared and filled into the perforated graphite rod to prepare the anode. At this time, in the consumable part of the anode, the amount of aluminum hydroxide used was 0.070 times the amount of graphite used, and the amount of aluminum hydroxide used was 1.79 times the total amount of nickel, cobalt, and ferrous sulfide used. A pure graphite rod with a diameter of 8 mm was used as the cathode. The two electrodes were placed horizontally opposite each other. The electric arc furnace cavity was evacuated to below 20 Pa, and helium gas was introduced at 30 kPa. This was repeated three times. The cathode and anode were brought into contact. The DC welding arc power supply was turned on. The distance between the cathode and anode was adjusted to 8 mm, and the discharge current was adjusted to 60 A. The arc discharge lasted for about 5 minutes. The generated gray-black carbon nanotube products were collected on the furnace wall.

[0074] In the eighth embodiment of the present invention, a density of 1.85 g·cm³ is used. -3 A perforated graphite rod with an outer diameter of 6 mm, an inner diameter of 4 mm, a hole depth of 40 mm, and a total length of 60 mm was made from graphite. A mixed powder with a weight ratio of graphite:nickel:cobalt:ferrous sulfide:calcium sulfate = 5:6:6:1:30 was prepared and filled into the perforated graphite rod to prepare the anode. At this time, in the consumable part of the anode, the amount of calcium sulfate was 0.042 times the amount of graphite, and the amount of calcium sulfate was 1.02 times the total amount of nickel, cobalt, and ferrous sulfide. A pure graphite rod with a diameter of 8 mm was used as the cathode. The two electrodes were placed horizontally opposite each other. The electric arc furnace cavity was evacuated to below 20 Pa, and helium gas was introduced at 30 kPa. This process was repeated three times. The cathode and anode were brought into contact. The DC welding arc power supply was turned on, the distance between the cathode and anode was adjusted to 8 mm, the discharge current was adjusted to 60 A, and the arc discharge lasted for about 5 minutes. The generated gray-black carbon nanotube products were collected on the furnace wall.

[0075] In the ninth embodiment of the present invention, a density of 1.85 g·cm³ is used. -3 A perforated graphite rod with an outer diameter of 6 mm, an inner diameter of 4 mm, a hole depth of 40 mm, and a total length of 60 mm was made from graphite. A mixed powder with a weight ratio of graphite:nickel:cobalt:ferrous sulfide:strontium chloride = 5:6:6:1:30 was prepared and filled into the perforated graphite rod to prepare the anode. At this time, in the consumable part of the anode, the amount of strontium chloride was 0.041 times the amount of graphite, and the amount of strontium chloride was 0.88 times the total amount of nickel, cobalt, and ferrous sulfide. A pure graphite rod with a diameter of 8 mm was used as the cathode. The two electrodes were placed horizontally opposite each other. The electric arc furnace cavity was evacuated to below 20 Pa, and helium gas was introduced at 30 kPa. This process was repeated three times. The cathode and anode were brought into contact. The DC welding arc power supply was turned on, the distance between the cathode and anode was adjusted to 8 mm, the discharge current was adjusted to 60 A, and the arc discharge lasted for about 5 minutes. The generated gray-black carbon nanotube products were collected on the furnace wall.

[0076] In the tenth embodiment of the present invention, a density of 1.85 g·cm³ is used. -3A perforated graphite rod with an outer diameter of 6 mm, an inner diameter of 4 mm, a hole depth of 40 mm, and a total length of 60 mm was made from graphite. A mixed powder with a weight ratio of graphite:nickel:cobalt:ferrous sulfide:barium carbonate = 5:6:6:1:30 was prepared and filled into the perforated graphite rod to prepare the anode. At this time, in the consumable part of the anode, the amount of barium carbonate used was 0.036 times the amount of graphite used, and the amount of barium carbonate used was 0.71 times the total amount of nickel, cobalt, and ferrous sulfide used. A pure graphite rod with a diameter of 8 mm was used as the cathode. The two electrodes were placed horizontally opposite each other. The electric arc furnace cavity was evacuated to below 20 Pa, and helium gas was introduced at 30 kPa. This was repeated three times. The cathode and anode were brought into contact. The DC welding arc power supply was turned on, the distance between the cathode and anode was adjusted to 8 mm, the discharge current was adjusted to 60 A, and the arc discharge lasted for about 5 minutes. The generated gray-black carbon nanotube products were collected on the furnace wall.

[0077] In the first comparative example of the present invention, a density of 1.85 g·cm³ was used. -3 A perforated graphite rod with an outer diameter of 6 mm, an inner diameter of 4 mm, a hole depth of 40 mm, and a total length of 60 mm was made from graphite. A mixed powder with a weight ratio of graphite:nickel:cobalt:ferrous sulfide = 5:6:6:1 was prepared and filled into the perforated graphite rod to prepare the anode. A pure graphite rod with a diameter of 8 mm was used as the cathode. The two electrodes were placed horizontally opposite each other. The electric arc furnace cavity was evacuated to below 20 Pa, and helium gas was introduced at 30 kPa. This process was repeated three times. The cathode and anode were brought into contact. The DC welding arc power supply was turned on. The distance between the cathode and anode was adjusted to 8 mm, and the discharge current was adjusted to 60 A. The arc discharge lasted for about 5 minutes. The gray-black carbon nanotube products generated were collected on the furnace wall.

[0078] The carbon nanotubes prepared in the first comparative example were tested using a scanning electron microscope, and the images are as follows. Figure 3 As shown, by Figure 3 It can be seen that single-walled carbon nanotubes can still be grown without introducing component A, which has no catalytic activity.

[0079] In the second comparative example of the present invention, a density of 1.85 g·cm³ was used. -3 A perforated graphite rod with an outer diameter of 6 mm, an inner diameter of 4 mm, a hole depth of 40 mm, and a total length of 60 mm was made from graphite. A mixed powder with a weight ratio of graphite:nickel:cobalt = 5:6:6 was prepared and filled into the perforated graphite rod to prepare the anode. A pure graphite rod with a diameter of 8 mm was used as the cathode. The two electrodes were placed horizontally opposite each other. The electric arc furnace cavity was evacuated to below 20 Pa, and helium gas was introduced at 30 kPa. This process was repeated three times. The cathode and anode were brought into contact. The DC welding arc power supply was turned on. The distance between the cathode and anode was adjusted to 8 mm, and the discharge current was adjusted to 60 A. The arc discharge lasted for about 5 minutes. The gray-black carbon nanotube products generated were collected on the furnace wall.

[0080] In the third comparative example of the present invention, a density of 1.85 g·cm³ was used. -3 A perforated graphite rod with an outer diameter of 6 mm, an inner diameter of 4 mm, a hole depth of 40 mm, and a total length of 60 mm was made from graphite. A mixed powder with a weight ratio of graphite:nickel = 5:12 was prepared and filled into the perforated graphite rod to prepare the anode. A pure graphite rod with a diameter of 8 mm was used as the cathode. The two electrodes were placed horizontally opposite each other. The electric arc furnace cavity was evacuated to below 20 Pa, and helium gas was introduced at 30 kPa. This process was repeated three times. The cathode and anode were brought into contact. The DC welding arc power supply was turned on. The distance between the cathode and anode was adjusted to 8 mm, and the discharge current was adjusted to 60 A. The arc discharge lasted for about 5 minutes. The gray-black carbon nanotube products generated were collected on the furnace wall.

[0081] Specifically, field emission transmission electron microscopy was used to image the carbon nanotubes prepared in the sixth embodiment and the second comparative embodiment, respectively.

[0082] The transmission electron microscope image corresponding to the sixth embodiment is shown in Figure 4(a). By performing tube diameter distribution statistics on the transmission electron microscope image corresponding to the sixth embodiment, the tube diameter distribution statistics diagram corresponding to the sixth embodiment is shown in Figure 4(b). As can be seen from Figure 4(b), the diameter of the carbon nanotubes prepared after introducing magnesium carbonate is relatively small, about 1.08±0.11nm, indicating that the introduction of magnesium carbonate can effectively reduce the diameter of carbon nanotubes in the sample.

[0083] The transmission electron microscope image corresponding to the second comparative example is shown in Figure 5(a). By performing tube diameter distribution statistics on the transmission electron microscope image corresponding to the second comparative example, the tube diameter distribution statistics diagram corresponding to the second comparative example is shown in Figure 5(b). As can be seen from Figure 5(b), the carbon nanotubes prepared without the introduction of ferrous sulfide and component A which has no catalytic activity have a larger diameter, approximately 1.36±0.19 nm. The introduction of component A which has no catalytic activity can effectively reduce the diameter of carbon nanotubes in the sample.

[0084] Specifically, Raman spectroscopy was used to perform Raman tests on the carbon nanotubes prepared in the first embodiment, second embodiment, third embodiment, fourth embodiment, fifth embodiment, sixth embodiment, seventh embodiment, eighth embodiment, ninth embodiment, tenth embodiment, first comparative example, second comparative example, and third comparative example at a laser wavelength of 785 nm.

[0085] The Raman spectra of the carbon nanotubes prepared in the first embodiment and the first comparative embodiment at a wavelength of 785 nm are shown below. Figure 6 As shown, the relative intensity of the high wavenumber peaks in the first embodiment is stronger than that in the first comparative example, meaning that the relative content of small-diameter carbon nanotubes obtained in the first embodiment is higher than that in the first comparative example. The Raman peaks in the first embodiment are concentrated at 163 cm⁻¹.-1 -198cm -1 Within this range, the corresponding carbon nanotube diameters range from 1.15 nm to 1.40 nm, and the Raman peaks corresponding to the first comparative example are concentrated at 147 cm⁻¹. -1 -184cm -1 Within this range, the corresponding carbon nanotube diameter ranges from 1.24 nm to 1.55 nm, indicating that the introduction of sodium borate is beneficial to reducing the diameter of the obtained carbon nanotubes.

[0086] The Raman spectra of the carbon nanotubes prepared in the second embodiment and the first comparative embodiment at a wavelength of 785 nm are shown below. Figure 7 As shown, the relative intensity of the high wavenumber peaks in the second embodiment is stronger than that in the first comparative example, meaning that the relative content of small-diameter carbon nanotubes obtained in the second embodiment is higher than that in the first comparative example. The Raman peaks in the second embodiment are concentrated at 179 cm⁻¹. -1 -228cm -1 Within this range, the corresponding carbon nanotube diameters range from 1.00 nm to 1.27 nm, and the Raman peaks corresponding to the first comparative example are concentrated at 147 cm⁻¹. -1 -184cm -1 Within this range, the corresponding carbon nanotube diameter ranges from 1.24 nm to 1.55 nm, indicating that the introduction of magnesium oxide is beneficial to reducing the diameter of the obtained carbon nanotubes.

[0087] The Raman spectra of the carbon nanotubes prepared in the third embodiment and the second comparative embodiment at a wavelength of 785 nm are shown below. Figure 8 As shown, the relative intensity of the high wavenumber peaks in the third embodiment is stronger than that in the second comparative example, meaning that the relative content of small-diameter carbon nanotubes obtained in the third embodiment is higher than that in the second comparative example. The Raman peaks in the third embodiment are concentrated at 164 cm⁻¹. -1 -184cm -1 Within this range, the corresponding carbon nanotube diameters range from 1.24 nm to 1.39 nm, and the Raman peaks corresponding to the second comparative example are concentrated at 147 cm⁻¹. -1 -177cm -1 Within this range, the corresponding carbon nanotube diameter ranges from 1.28 nm to 1.55 nm, indicating that the introduction of magnesium oxide is beneficial to reducing the diameter of the obtained carbon nanotubes.

[0088] The Raman spectra of the carbon nanotubes prepared in the fourth embodiment and the third comparative embodiment at a wavelength of 785 nm are shown below. Figure 9 As shown, the relative intensity of the high wavenumber peaks in the fourth embodiment is stronger than that in the third comparative example, meaning that the relative content of small-diameter carbon nanotubes obtained in the fourth embodiment is higher than that in the third comparative example. The Raman peaks in the fourth embodiment are concentrated at 184 cm⁻¹.-1 -228cm -1 Within this range, the corresponding carbon nanotube diameters range from 1.00 nm to 1.24 nm, and the Raman peaks corresponding to the third comparative example are concentrated at 147 cm⁻¹. -1 -160cm -1 Within this range, the corresponding carbon nanotube diameter ranges from 1.42 nm to 1.55 nm, indicating that the introduction of magnesium oxide is beneficial to reducing the diameter of the obtained carbon nanotubes.

[0089] The Raman spectra of the carbon nanotubes prepared in the fifth embodiment and the third comparative embodiment at a wavelength of 785 nm are shown below. Figure 10 As shown, the relative intensity of the high wavenumber peaks in the fifth embodiment is stronger than that in the third comparative example, meaning that the relative content of small-diameter carbon nanotubes obtained in the fifth embodiment is higher than that in the third comparative example. The Raman peaks in the fifth embodiment are concentrated at 178 cm⁻¹. -1 -198cm -1 Within this range, the corresponding carbon nanotube diameters range from 1.15 nm to 1.28 nm, and the Raman peaks corresponding to the third comparative example are concentrated at 147 cm⁻¹. -1 -160cm -1 Within this range, the corresponding carbon nanotube diameter ranges from 1.42 nm to 1.55 nm, indicating that the introduction of magnesium carbonate is beneficial to reducing the diameter of the obtained carbon nanotubes.

[0090] The Raman spectra of the carbon nanotubes prepared in the sixth embodiment and the first comparative embodiment at a wavelength of 785 nm are shown below. Figure 11 As shown, the relative intensity of the high wavenumber peaks in the sixth embodiment is stronger than that in the first comparative example, meaning that the relative content of small-diameter carbon nanotubes obtained in the sixth embodiment is higher than that in the first comparative example. The Raman peaks in the sixth embodiment are concentrated at 179 cm⁻¹. -1 -228cm -1 Within this range, the corresponding carbon nanotube diameters range from 1.00 nm to 1.27 nm, and the Raman peaks corresponding to the first comparative example are concentrated at 147 cm⁻¹. -1 -184cm -1 Within this range, the corresponding carbon nanotube diameter ranges from 1.24 nm to 1.55 nm, indicating that the introduction of magnesium carbonate is beneficial to reducing the diameter of the obtained carbon nanotubes.

[0091] The Raman spectra of the carbon nanotubes prepared in the seventh embodiment and the first comparative embodiment at a wavelength of 785 nm are shown below. Figure 12 As shown, the relative intensity of the high wavenumber peaks in the seventh embodiment is stronger than that in the first comparative example, meaning that the relative content of small-diameter carbon nanotubes obtained in the seventh embodiment is higher than that in the first comparative example. The Raman peaks in the seventh embodiment are concentrated at 162 cm⁻¹.-1 -198cm -1 Within this range, the corresponding carbon nanotube diameters range from 1.15 nm to 1.40 nm, and the Raman peaks corresponding to the first comparative example are concentrated at 147 cm⁻¹. -1 -184cm -1 Within this range, the corresponding carbon nanotube diameter ranges from 1.24 nm to 1.55 nm, indicating that the introduction of aluminum hydroxide is beneficial to reducing the diameter of the obtained carbon nanotubes.

[0092] The Raman spectra of the carbon nanotubes prepared in the eighth embodiment and the first comparative embodiment at a wavelength of 785 nm are shown below. Figure 13 As shown, the relative intensity of the high wavenumber peaks in the eighth embodiment is stronger than that in the first comparative example, meaning that the relative content of small-diameter carbon nanotubes obtained in the eighth embodiment is higher than that in the first comparative example. The Raman peaks in the eighth embodiment are concentrated at 162 cm⁻¹. -1 -228cm -1 Within this range, the corresponding carbon nanotube diameters range from 1.00 nm to 1.40 nm, and the Raman peaks corresponding to the first comparative example are concentrated at 147 cm⁻¹. -1 -184cm -1 Within this range, the corresponding carbon nanotube diameter ranges from 1.24 nm to 1.55 nm, indicating that the introduction of calcium sulfate is beneficial to reducing the diameter of the obtained carbon nanotubes.

[0093] The Raman spectra of the carbon nanotubes prepared in the ninth embodiment and the first comparative embodiment at a wavelength of 785 nm are shown below. Figure 14 As shown, the relative intensity of the high wavenumber peaks in the ninth embodiment is stronger than that in the first comparative example, meaning that the relative content of small-diameter carbon nanotubes obtained in the ninth embodiment is higher than that in the first comparative example. The Raman peaks in the ninth embodiment are concentrated at 162 cm⁻¹. -1 -228cm -1 Within this range, the corresponding carbon nanotube diameters range from 1.00 nm to 1.40 nm, and the Raman peaks corresponding to the first comparative example are concentrated at 147 cm⁻¹. -1 -184cm -1 Within this range, the corresponding carbon nanotube diameter ranges from 1.24 nm to 1.55 nm, indicating that the introduction of strontium chloride is beneficial to reducing the diameter of the obtained carbon nanotubes.

[0094] The Raman spectra of the carbon nanotubes prepared in the tenth embodiment and the first comparative embodiment at a wavelength of 785 nm are shown below. Figure 15 As shown, the relative intensity of the high wavenumber peaks in the tenth embodiment is stronger than that in the first comparative example, meaning that the relative content of small-diameter carbon nanotubes obtained in the tenth embodiment is higher than that in the first comparative example. The Raman peaks in the tenth embodiment are concentrated at 162 cm⁻¹.-1 -228cm -1 Within this range, the corresponding carbon nanotube diameters range from 1.00 nm to 1.40 nm, and the Raman peaks corresponding to the first comparative example are concentrated at 147 cm⁻¹. -1 -184cm -1 Within this range, the corresponding carbon nanotube diameter ranges from 1.24 nm to 1.55 nm, indicating that the introduction of barium carbonate is beneficial to reducing the diameter of the obtained carbon nanotubes.

[0095] Specifically, 1 mg of carbon nanotube samples prepared in the first embodiment, 1 mg of carbon nanotube samples prepared in the second embodiment, 1 mg of carbon nanotube samples prepared in the third embodiment, 1 mg of carbon nanotube samples prepared in the fifth embodiment, 1 mg of carbon nanotube samples prepared in the sixth embodiment, 1 mg of carbon nanotube samples prepared in the seventh embodiment, 1 mg of carbon nanotube samples prepared in the eighth embodiment, 1 mg of carbon nanotube samples prepared in the ninth embodiment, 1 mg of carbon nanotube samples prepared in the tenth embodiment, 1 mg of carbon nanotube samples prepared in the first comparative example, and 1 mg of carbon nanotube samples prepared in the second comparative example were respectively placed in a 2% (w / w) sodium deoxycholate aqueous solution, ultrasonically treated for 90 minutes using an ultrasonic homogenizer, and centrifuged for 90 minutes using a micro-crystal centrifuge. The supernatant obtained by centrifugation was measured using a UV-Vis-NIR spectrophotometer with an optical path of 10 mm.

[0096] The baseline-subtracted and normalized absorption spectra of the carbon nanotubes prepared in the first embodiment and the first comparative embodiment are as follows: Figure 16As shown, the absorption peak positions of the carbon nanotube samples prepared in the first embodiment are significantly smaller than those in the first comparative example. The S11 peak corresponding to the first embodiment is located at 1671 nm, and the possible chiral diameter within a range of ±15 nm is 1.317 nm. The S22 peak corresponding to the first embodiment is located at 943 nm, and the possible chiral diameter within a range of ±15 nm is 1.215 nm-1.487 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the first embodiment is located at 1533 nm-1845 nm, and the possible chiral diameter within this range is 1.230 nm-1.572 nm. The FWHM of the S22 peak corresponding to the first embodiment is located at 875 nm-1043 nm, and the possible chiral diameter within this range is 1.215 nm-1.618 nm. The S11 peak corresponding to the first comparative example is located at 1728 nm, and the possible chiral diameter range within ±15 nm is 1.424 nm-1.463 nm. The S22 peak corresponding to the first comparative example is located at 1004 nm, and the possible chiral diameter range within ±15 nm is 1.331 nm-1.542 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the first comparative example is located at 1555 nm-1920 nm, and the possible chiral diameter range within this range is 1.253 nm-1.618 nm. The FWHM of the S22 peak corresponding to the first comparative example is located at 893 nm-1079 nm, and the possible chiral diameter range within this range is 1.215 nm-1.640 nm. This indicates that the introduction of sodium borate can effectively reduce the diameter of carbon nanotubes in the sample.

[0097] The baseline-subtracted and normalized absorption spectra of the carbon nanotubes prepared in the second embodiment and the first comparative embodiment are as follows: Figure 17As shown, the absorption peak positions of the carbon nanotube samples prepared in the second embodiment are significantly smaller than those in the first comparative example. The S11 peak corresponding to the second embodiment is located at 1662 nm, and the possible chiral diameter range within ±15 nm is 1.282 nm-1.392 nm. The S22 peak corresponding to the second embodiment is located at 940 nm, and the possible chiral diameter range within ±15 nm is 1.215 nm-1.411 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the second embodiment is located at 1477 nm-1796 nm, and the possible chiral diameter range within this range is 1.137 nm-1.494 nm. The FWHM of the S22 peak corresponding to the second embodiment is located at 849 nm-1024 nm, and the possible chiral diameter range within this range is 1.096 nm- The S11 peak corresponding to the first comparative example is located at 1728 nm, and the possible chiral diameter range within ±15 nm is 1.424 nm-1.463 nm. The S22 peak corresponding to the first comparative example is located at 1004 nm, and the possible chiral diameter range within ±15 nm is 1.331 nm-1.542 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the first comparative example is located at 1555 nm-1920 nm, and the possible chiral diameter range within this range is 1.253 nm-1.618 nm. The FWHM of the S22 peak corresponding to the first comparative example is located at 893 nm-1079 nm, and the possible chiral diameter range within this range is 1.215 nm-1.640 nm. This indicates that the introduction of magnesium oxide can effectively reduce the diameter of carbon nanotubes in the sample.

[0098] The absorption spectra of the carbon nanotubes prepared in the third embodiment and the second comparative embodiment, after baseline subtraction and normalization, are as follows: Figure 18As shown, the absorption peak positions of the carbon nanotube samples prepared in the third embodiment are significantly smaller than those in the second comparative example. The S11 peak corresponding to the third embodiment is located at 1625 nm, and the possible chiral diameter range within ±20 nm is 1.253 nm-1.358 nm. The S22 peak corresponding to the third embodiment is located at 935 nm, and the possible chiral diameter range within ±15 nm is 1.215 nm-1.411 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the third embodiment is located at 1421 nm-1755 nm, and the possible chiral diameter range within this range is 1.137 nm-1.487 nm. The FWHM of the S22 peak corresponding to the third embodiment is located at 839 nm-1005 nm, and the possible chiral diameter range within this range is 1.0 nm. The S11 peak corresponding to the second comparative example is located at 1673 nm, with a possible chiral diameter of 1.317 nm within a range of ±15 nm. The S22 peak corresponding to the second comparative example is located at 944 nm, with a possible chiral diameter range of 1.215 nm-1.487 nm within a range of ±15 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the second comparative example is located at 1551 nm-1849 nm, with a possible chiral diameter range of 1.253 nm-1.572 nm within this range. The FWHM of the S22 peak corresponding to the second comparative example is located at 883 nm-1058 nm, with a possible chiral diameter range of 1.215 nm-1.618 nm within this range. This indicates that the introduction of magnesium oxide can effectively reduce the diameter of carbon nanotubes in the sample.

[0099] The baseline-subtracted and normalized absorption spectra of the carbon nanotubes prepared in the fifth embodiment and the first comparative embodiment are as follows: Figure 19As shown, the absorption peak positions of the carbon nanotube samples prepared in the fifth embodiment are significantly smaller than those in the first comparative example. The S11 peak corresponding to the fifth embodiment is located at 1578 nm, and the possible chiral diameter range within ±15 nm is 1.289 nm-1.338 nm. The S22 peak corresponding to the fifth embodiment is located at 938 nm, and the possible chiral diameter range within ±15 nm is 1.215 nm-1.411 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the fifth embodiment is located at 1410 nm-1734 nm, and the possible chiral diameter range within this range is 1.137 nm-1.463 nm. The FWHM of the S22 peak corresponding to the fifth embodiment is located at 811 nm-979 nm, and the possible chiral diameter range within this range is 1.096 nm-1. The S11 peak corresponding to the first comparative example is located at 1728 nm, and the possible chiral diameter range within ±15 nm is 1.424 nm-1.463 nm. The S22 peak corresponding to the first comparative example is located at 1004 nm, and the possible chiral diameter range within ±15 nm is 1.331 nm-1.542 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the first comparative example is located at 1555 nm-1920 nm, and the possible chiral diameter range within this range is 1.253 nm-1.618 nm. The FWHM of the S22 peak corresponding to the first comparative example is located at 893 nm-1079 nm, and the possible chiral diameter range within this range is 1.215 nm-1.640 nm. This indicates that the introduction of magnesium carbonate can effectively reduce the diameter of carbon nanotubes in the sample.

[0100] The baseline-subtracted and normalized absorption spectra of the carbon nanotubes prepared in the sixth embodiment and the second comparative embodiment are as follows: Figure 20As shown, the absorption peak positions of the carbon nanotube samples prepared in the sixth embodiment are significantly smaller than those in the second comparative example. The S11 peak corresponding to the sixth embodiment is located at 1417 nm, and the possible chiral diameter range within ±15 nm is 1.096 nm-1.169 nm. The S22 peak corresponding to the sixth embodiment is located at 861 nm, and the possible chiral diameter range within ±15 nm is 1.096 nm-1.223 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the sixth embodiment is located at 1343 nm-1522 nm, and the possible chiral diameter range within this range is 1.018 nm-1.260 nm. The FWHM of the S22 peak corresponding to the sixth embodiment is located at 752 nm-899 nm, and the possible chiral diameter range within this range is 0.9 nm. The S11 peak corresponding to the second comparative example is located at 1673 nm, with a possible chiral diameter of 1.317 nm within a range of ±15 nm. The S22 peak corresponding to the second comparative example is located at 944 nm, with a possible chiral diameter range of 1.215 nm-1.487 nm within a range of ±15 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the second comparative example is located at 1551 nm-1849 nm, with a possible chiral diameter range of 1.253 nm-1.572 nm within this range. The FWHM of the S22 peak corresponding to the second comparative example is located at 883 nm-1058 nm, with a possible chiral diameter range of 1.215 nm-1.618 nm within this range. This indicates that the introduction of magnesium carbonate can effectively reduce the diameter of carbon nanotubes in the sample.

[0101] The baseline-subtracted and normalized absorption spectra of the carbon nanotubes prepared in the seventh embodiment and the first comparative embodiment are as follows: Figure 21As shown, the absorption peak positions of the carbon nanotube samples prepared in the seventh embodiment are significantly smaller than those in the first comparative example. The S11 peak corresponding to the seventh embodiment is located at 1664 nm, and the possible chiral diameter range within ±15 nm is 1.282 nm-1.392 nm. The S22 peak corresponding to the seventh embodiment is located at 939 nm, and the possible chiral diameter range within ±15 nm is 1.215 nm-1.411 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the seventh embodiment is located at 1465 nm-1837 nm, and the possible chiral diameter range within this range is 1.137 nm-1.566 nm. The FWHM of the S22 peak corresponding to the seventh embodiment is located at 851 nm-1030 nm, and the possible chiral diameter range within this range is 1.096 nm-1. The S11 peak corresponding to the first comparative example is located at 1728 nm, and the possible chiral diameter range within ±15 nm is 1.424 nm-1.463 nm. The S22 peak corresponding to the first comparative example is located at 1004 nm, and the possible chiral diameter range within ±15 nm is 1.331 nm-1.542 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the first comparative example is located at 1555 nm-1920 nm, and the possible chiral diameter range within this range is 1.253 nm-1.618 nm. The FWHM of the S22 peak corresponding to the first comparative example is located at 893 nm-1079 nm, and the possible chiral diameter range within this range is 1.215 nm-1.640 nm. This indicates that the introduction of aluminum hydroxide can effectively reduce the diameter of carbon nanotubes in the sample.

[0102] The baseline-subtracted and normalized absorption spectra of the carbon nanotubes prepared in the eighth embodiment and the first comparative embodiment are as follows: Figure 22As shown, the absorption peak positions of the carbon nanotube samples prepared in the eighth embodiment are significantly smaller than those in the first comparative example. The S11 peak corresponding to the eighth embodiment is located at 1656 nm, and the possible chiral diameter range within ±15 nm is 1.253 nm-1.392 nm. The S22 peak corresponding to the eighth embodiment is located at 938 nm, and the possible chiral diameter range within ±15 nm is 1.215 nm-1.411 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the eighth embodiment is located at 1385 nm-1831 nm, and the possible chiral diameter range within this range is 1.018 nm-1.524 nm. The FWHM of the S22 peak corresponding to the eighth embodiment is located at 786 nm-1028 nm, and the possible chiral diameter range within this range is 0.981 nm- The S11 peak corresponding to the first comparative example is located at 1728 nm, and the possible chiral diameter range within ±15 nm is 1.424 nm-1.463 nm. The S22 peak corresponding to the first comparative example is located at 1004 nm, and the possible chiral diameter range within ±15 nm is 1.331 nm-1.542 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the first comparative example is located at 1555 nm-1920 nm, and the possible chiral diameter range within this range is 1.253 nm-1.618 nm. The FWHM of the S22 peak corresponding to the first comparative example is located at 893 nm-1079 nm, and the possible chiral diameter range within this range is 1.215 nm-1.640 nm. This indicates that the introduction of calcium sulfate can effectively reduce the diameter of carbon nanotubes in the sample.

[0103] The baseline-subtracted and normalized absorption spectra of the carbon nanotubes prepared in the ninth embodiment and the first comparative embodiment are as follows: Figure 23As shown, the absorption peak positions of the carbon nanotube samples prepared in the ninth embodiment are significantly smaller than those in the first comparative example. The S11 peak corresponding to the ninth embodiment is located at 1667 nm, and the possible chiral diameter range within ±15 nm is 1.282 nm-1.392 nm. The S22 peak corresponding to the ninth embodiment is located at 941 nm, and the possible chiral diameter range within ±15 nm is 1.215 nm-1.411 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the ninth embodiment is located at 1506 nm-1792 nm, and the possible chiral diameter range within this range is 1.137 nm-1.487 nm. The FWHM of the S22 peak corresponding to the ninth embodiment is located at 856 nm-1033 nm, and the possible chiral diameter range within this range is 1.096 nm- The S11 peak corresponding to the first comparative example is located at 1728 nm, and the possible chiral diameter range within ±15 nm is 1.424 nm-1.463 nm. The S22 peak corresponding to the first comparative example is located at 1004 nm, and the possible chiral diameter range within ±15 nm is 1.331 nm-1.542 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the first comparative example is located at 1555 nm-1920 nm, and the possible chiral diameter range within this range is 1.253 nm-1.618 nm. The FWHM of the S22 peak corresponding to the first comparative example is located at 893 nm-1079 nm, and the possible chiral diameter range within this range is 1.215 nm-1.640 nm. This indicates that the introduction of strontium chloride can effectively reduce the diameter of carbon nanotubes in the sample.

[0104] The baseline-subtracted and normalized absorption spectra of the carbon nanotubes prepared in the tenth embodiment and the first comparative embodiment are as follows: Figure 24As shown, the absorption peak positions of the carbon nanotube samples prepared in the tenth embodiment are significantly smaller than those in the first comparative example. The S11 peak corresponding to the tenth embodiment is located at 1637 nm, and the possible chiral diameter range within ±15 nm is 1.253 nm-1.358 nm. The S22 peak corresponding to the tenth embodiment is located at 934 nm, and the possible chiral diameter range within ±15 nm is 1.215 nm-1.411 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the tenth embodiment is located at 1412 nm-1786 nm, and the possible chiral diameter range within this range is 1.137 nm-1.487 nm. The FWHM of the S22 peak corresponding to the tenth embodiment is located at 823 nm-1016 nm, and the possible chiral diameter range within this range is 1.096 nm- The S11 peak corresponding to the first comparative example is located at 1728 nm, and the possible chiral diameter range within ±15 nm is 1.424 nm-1.463 nm. The S22 peak corresponding to the first comparative example is located at 1004 nm, and the possible chiral diameter range within ±15 nm is 1.331 nm-1.542 nm. The full width at half maximum (FWHM) of the S11 peak corresponding to the first comparative example is located at 1555 nm-1920 nm, and the possible chiral diameter range within this range is 1.253 nm-1.618 nm. The FWHM of the S22 peak corresponding to the first comparative example is located at 893 nm-1079 nm, and the possible chiral diameter range within this range is 1.215 nm-1.640 nm. This indicates that the introduction of barium carbonate can effectively reduce the diameter of carbon nanotubes in the sample.

[0105] Specifically, based on the above results of imaging and diameter distribution statistics of carbon nanotubes prepared in the corresponding examples and comparative examples using field emission transmission electron microscopy, Raman spectroscopy results of Raman tests performed on carbon nanotubes prepared in each example and comparative example at laser wavelengths of 532 nm, 633 nm, and 785 nm, and the results of measuring the supernatant of the corresponding examples and comparative examples using an optical path ultraviolet-visible-near-infrared spectrophotometer, the following table is obtained:

[0106] Table 1. Summary of diameter reduction results caused by the addition of non-catalytically active component A under different conditions.

[0107]

[0108] It should be noted that the above detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0109] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0110] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0111] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0112] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways, such as rotated 90 degrees or in other orientations, and the spatial relative descriptions used herein will be interpreted accordingly.

[0113] In the detailed description above, reference has been made to the accompanying drawings, which form part of this document. In the drawings, similar symbols typically identify similar parts unless the context otherwise indicates otherwise. The illustrated embodiments described in the detailed specification, drawings, and claims are not intended to be limiting. Other embodiments may be used and other changes may be made without departing from the spirit or scope of the subject matter presented herein.

[0114] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling the diameter of single-walled carbon nanotubes prepared by arc discharge, characterized in that, The method includes: An anode comprising a metal catalyst, a carbon raw material, and a component A without catalytic activity is prepared, and the anode and a pure graphite rod cathode are placed in an electric arc furnace. The component A without catalytic activity is selected from one or more of the following: elemental boron, boron oxide, magnesium oxide, aluminum oxide, calcium oxide, gallium oxide, indium oxide, strontium oxide, barium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, gallium hydroxide, indium hydroxide, strontium hydroxide, barium hydroxide, salts containing boron, salts containing magnesium, salts containing aluminum, salts containing calcium, salts containing gallium, salts containing indium, salts containing strontium, and salts containing barium. A set atmosphere is introduced into the electric arc furnace, the cathode and anode are brought into contact and a set current is passed through. After conduction, the distance between the cathode and anode is increased to maintain the electric arc discharge. Under the action of the electric arc, the anode is continuously consumed, and the generated gray-black carbon nanotube products are collected on the furnace wall.

2. The method for controlling the diameter of single-walled carbon nanotubes obtained by arc discharge according to claim 1, characterized in that, Component A, which is not catalytically active, is one or more of the following: magnesium oxide, calcium oxide, strontium oxide, barium oxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, salts containing magnesium, salts containing calcium, salts containing strontium, and salts containing barium.

3. The method for controlling the diameter of single-walled carbon nanotubes obtained by arc discharge according to claim 1, characterized in that, Component A, which is not catalytically active, is made of sodium borate, magnesium oxide, magnesium carbonate, aluminum hydroxide, calcium sulfate, strontium chloride, or barium carbonate.

4. The method for controlling the diameter of single-walled carbon nanotubes obtained by arc discharge according to claim 1, characterized in that, The metal catalyst is one or more of the following: scandium, iron, cobalt, nickel, yttrium, molybdenum, tungsten, scandium oxide, iron oxide, cobalt oxide, nickel oxide, yttrium oxide, molybdenum oxide, tungsten oxide, scandium sulfide, iron sulfide, cobalt sulfide, nickel sulfide, yttrium sulfide, molybdenum sulfide, and tungsten sulfide.

5. The method for controlling the diameter of single-walled carbon nanotubes obtained by arc discharge according to claim 4, characterized in that, The metal catalyst is selected from two or three of the following: elemental iron, elemental cobalt, elemental nickel, elemental yttrium, iron oxide, cobalt oxide, nickel oxide, yttrium oxide, iron sulfide, cobalt sulfide, nickel sulfide, and yttrium sulfide.

6. The method for controlling the diameter of single-walled carbon nanotubes obtained by arc discharge according to claim 1, characterized in that, The amount of component A, which has no catalytic activity, is 0-100 times that of the metal catalyst, and the amount of component A, which has no catalytic activity, is 0-5 times that of the carbon raw material.

7. The method for controlling the diameter of single-walled carbon nanotubes obtained by arc discharge according to claim 1, characterized in that, The atmosphere introduced into the electric arc furnace is one or two of hydrogen, helium, nitrogen, and argon.

8. The method for controlling the diameter of single-walled carbon nanotubes obtained by arc discharge according to claim 1, characterized in that, Before the cathode and anode come into contact, the total pressure in the electric arc furnace is 30 kPa-100 kPa.

9. The method for controlling the diameter of single-walled carbon nanotubes obtained by arc discharge according to claim 1, characterized in that, During the arc discharge process, the distance between the cathode and the anode is 1mm-20mm.

10. The method for controlling the diameter of single-walled carbon nanotubes obtained by arc discharge according to claim 1, characterized in that, The current of the arc discharge is 40-80A, and the voltage of the arc discharge is 15-50V.

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