CN103466593A - Improved temperature control electric arc furnace and method for preparing semiconductor single wall carbon nano tubes - Google Patents

Abstract

The invention relates to an improved temperature-controlled electric arc furnace and a method for preparing semiconductor-type single-walled carbon nanotubes, including a vacuum container, a movable cathode, a rotatable anode, an electrode feeding system and a temperature-controlled thermocouple; it is characterized in that it also includes and a pair of electrode plates; a pair of electrode plates are arranged on the upper and lower opposite sides of the heating device of the vacuum vessel, and 1 to 6 consumed anode rods can be installed on the turntable of the rotatable anode; the holes of the consumed anode rods are filled with catalyst and High-purity graphite powder; the cathode is a high-purity graphite rod. The difference between the present invention and the prior art is that most of the traditional methods for preparing semiconductor-type or metal-type single-walled carbon nanotubes are to physically and chemically separate the samples in the later stage, but the yield is low, the process is cumbersome and these methods are difficult to separate. The structure of single-walled carbon nanotubes is easily damaged during the process. The invention adopts a temperature-controlled electric arc furnace with an internal electric field, and the reaction vessel can produce single-wall carbon nanotubes with different structures under the action of different temperatures and electric fields.

Description

An improved temperature-controlled electric arc furnace and a method for preparing semiconducting single-walled carbon nanotubes

technical field

The invention belongs to the preparation of carbon nanotubes, and relates to an improved temperature-controlled electric arc furnace and a method for preparing semiconductor-type single-walled carbon nanotubes, in particular to a mass production of single-walled carbon nanotubes with different helical structures in a temperature-controlled electric arc furnace with an internal electric field. method for walled carbon nanotubes.

Background technique

In 1993, single-walled carbon nanotubes were prepared by Iijima [S.Iijima Nature 1993 (363)] and Bethune [DS Bethune, Nature, 1993 (363)]. At present, there are three main methods for preparing single-walled carbon nanotubes: arc discharge method, chemical vapor deposition method, and laser evaporation method; but the products prepared by all methods are mixtures of metallic and semiconducting single-walled carbon nanotubes. This has become the bottleneck of its wide application in many fields. Therefore, how to directly prepare a single semiconductor-type or metal-type single-walled carbon nanotubes, and to separate semiconductor-type and metal-type single-walled carbon nanotubes has become the research focus of many scientific researchers. For this reason, many researchers have done a lot of research. research work. For example, Alexander L [Alexander L, ACS NANO, 2010 (4)] used polyether and Tetronic as dispersants to successfully separate metal-type and semiconductor-type single-walled carbon nanotubes by the DGU method, and their purity was 74% and 99%; Liu [Liu HP, J.Phys.Chem.C.2010, (114)] et al. used agarose gel method, using SDS and DOC solutions as active agents, to achieve simultaneous separation of metallic and semiconducting single-walled carbon nanotube. Materials Research Bulletin, 2011 (46)] and others also reported that agarose gel was used as the absorbent of semiconducting carbon nanotubes, and two kinds of carbon nanotubes of metallic type and semiconducting type were separated simultaneously by the cryo-extrusion method. S.kawasaki [S.Kawasaki, Materials Letters, 2008 (62)] et al. added single-walled carbon nanotube samples into a mixed acid mixed with HNO ₃ and H ₂ SO ₄ to reflux. The results showed that only semiconductor-type single-walled carbon nanotubes remained, while metal-type carbon tubes were removed; at the same time, the researchers replaced the mixed acid with H ₂ O ₂ solution, and found that semiconductor-type carbon nanotubes were removed, leaving only metal-type carbon nanotube. In addition, single-walled carbon nanotubes can also be selectively removed by the gas phase. At present, there is no report on the preparation of single-walled carbon nanotubes with different helical structures by introducing a direct current electric field in the arc equipment. For this reason, inventing a method for the controllable preparation of single-walled carbon nanotubes with different helical structures is of great significance to the research and application of carbon nanotubes.

Contents of the invention

technical problem to be solved

In order to avoid the deficiencies of the prior art, the invention proposes an improved temperature-controlled electric arc furnace and a method for preparing semiconductor-type single-walled carbon nanotubes.

Technical solutions

An improved temperature-controlled electric arc furnace, including a vacuum container 1, a movable cathode 2, a rotatable anode 5, an electrode feeding system 3 and a temperature-controlling thermocouple 4; it is characterized in that it also includes a pair of electrode plates 6; in a vacuum A pair of electrode plates are arranged on the upper and lower opposite sides of the heating device of the container 1, and 1 to 6 spent anode rods can be installed on the turntable of the rotatable anode 5; the holes of the spent anode rods are filled with catalyst and high-purity graphite powder; The cathode is a high-purity graphite rod.

A method for controllably preparing semiconducting single-walled carbon nanotubes using the improved temperature-controlled electric arc furnace, characterized in that the steps are as follows:

Step 1: Adjust the distance between the electrode plates to 3-20cm, and the DC voltage is less than or equal to 300V;

Adjust the distance between the electrode plates to cm, and the DC voltage is less than or equal to;

Step 2: The catalyst is introduced to be less than or equal to the total amount of 10wt%; the catalyst contains a powder mixture of ferrous sulfide, potassium chloride, ammonium molybdate, and metal nickel, magnesium, cobalt, and iron;

Step 3: Under the atmosphere of helium, helium and nitrogen or helium and argon, arc discharge at a current of 50-280A to obtain semiconducting single-walled carbon nanotubes.

Beneficial effect

The invention proposes an improved temperature-controlled electric arc furnace and a method for preparing semiconductor-type single-walled carbon nanotubes, using the applicant's invention patent (ZL200410026135.1 "A method for batch production of single-walled carbon nanotubes using a temperature-controlled electric arc furnace Method "Liu Yongning, Zhao Tingkai, etc.), by placing a pair of electrode plates in an electric arc furnace to introduce a DC electric field, providing a process for the controllable production of single-walled carbon nanotubes with different helical structures by a temperature-controlled arc method.

The difference between the present invention and the prior art is that most of the traditional methods for preparing semiconductor-type or metal-type single-walled carbon nanotubes are to physically and chemically separate the samples in the later stage, but the yield is low, the process is cumbersome and these methods are difficult to separate. The structure of single-walled carbon nanotubes is easily damaged during the process. The invention adopts a temperature-controlled electric arc furnace with an internal electric field, and the reaction vessel can produce single-wall carbon nanotubes with different structures under the action of different temperatures and electric fields.

The invention adopts an improved temperature-controlled electric arc furnace. A pair of electrode plates are placed in the furnace, and a direct current electric field is introduced. Under atmospheres such as helium, helium and nitrogen, helium and argon, using , ammonium molybdate and one or more powder mixtures of nickel, magnesium, cobalt, iron, etc. as a catalyst, can produce single-walled carbon nanotubes with different helical structures, which has broad prospects for industrial production and application.

Description of drawings

Fig. 1 is a schematic diagram of a device for controllably producing single-walled carbon nanotubes with different helical structures by introducing a direct current electric field through a temperature-controlled arc method. The symbols in Figure 1 represent: 1. Vacuum container, 2. Movable cathode, 3. Electrode feeding system, 4. Temperature control thermocouple, 5. Rotatable anode, 6. Electrode plate

Figure 2 X-ray diffraction pattern of single-walled carbon nanotubes

Figure 3 Laser Raman spectrum of single-walled carbon nanotubes (S in the figure represents semiconducting single-walled carbon nanotubes, M represents metallic single-walled carbon nanotubes, the same below)

Figure 4 High-resolution transmission electron microscope photo of single-walled carbon nanotubes

Figure 5 Laser Raman spectra of single-walled carbon nanotubes prepared under different DC voltage conditions

Figure 6 Laser Raman spectrum of single-walled carbon nanotubes prepared with a plate spacing of 10cm

Figure 7 Laser Raman spectrum of single-walled carbon nanotubes prepared on aluminum alloy plate substrate

Detailed ways

Now in conjunction with embodiment, accompanying drawing, the present invention will be further described:

The characteristic of the improved temperature-controlled electric arc furnace is that a pair of electrode plates are placed on the upper and lower sides of the cathode and anode inside the heating device of the cylindrical reaction vessel with a length of 400 mm and a diameter of 300 mm. ~200V) to control the electric field strength. Among them, 1 to 6 consumed anode rods can be installed on the anode turntable at the same time, and the holes of the consumed anode rods are filled with catalyst (0-10wt%) and high-purity graphite powder (90-100wt%), and the catalyst is 0-10wt% in total. Powder mixture containing ferrous sulfide, potassium chloride, ammonium molybdate and one or more metals such as nickel, magnesium, cobalt and iron; the cathode is a high-purity graphite rod; in helium, helium and nitrogen, helium and Arc discharge in an atmosphere such as argon can generate single-walled carbon nanotubes with different helical structures.

The technical solution is a temperature-controlled arc method for the controllable production of single-walled carbon nanotubes with different helical structures. Methods of producing single-walled carbon nanotubes" Liu Yongning, Zhao Tingkai, et al.). The equipment places a pair of electrode plates on the upper and lower sides of the cathode and anode, and introduces a DC electric field through the electrode plates; the anode turntable can install 1 to 6 consumable anode rods at the same time, and the cathode is a high-purity graphite rod with a diameter of 20mm and a length of 100-200mm. Single-walled carbon nanotubes with different helical structures were prepared by arc discharge in a helium atmosphere.

Example 1

The device is shown in Figure 1

Install a consumable anode rod on the anode turntable, the temperature is room temperature, helium atmosphere, the atmosphere pressure is 600torr, Ni-Co alloy powder is used as the catalyst, the arcing discharge current is 80A, the applied DC electric field voltage is 54V, and the distance between the plates is 120mm. The low carbon steel plate is the plate base. The X-ray diffraction pattern of the prepared single-walled carbon nanotubes is shown in Figure 2.

Example 2

The device is shown in Figure 1

Install a consumable anode rod on the anode turntable, the temperature is room temperature, helium atmosphere, the atmosphere pressure is 600torr, Ni-Co alloy powder is used as the catalyst, the arcing discharge current is 80A, the applied DC electric field voltage is 54V, and the distance between the plates is 120mm. The low carbon steel plate is the plate base. The laser Raman spectrum of the prepared single-walled carbon nanotubes is shown in Figure 3.

Example 3

The device is shown in Figure 1

Install a consumable anode rod on the anode turntable, the temperature is room temperature, helium atmosphere, the atmosphere pressure is 600torr, Ni-Co alloy powder is used as the catalyst, the arcing discharge current is 80A, the applied DC electric field voltage is 54V, and the distance between the plates is 120mm. The low carbon steel plate is the plate base. The high-resolution transmission photos of the prepared single-walled carbon nanotubes are shown in Figure 4.

Example 4

The device is shown in Figure 1

Install a consumable anode rod on the anode turntable, the temperature is room temperature, helium atmosphere, the atmosphere pressure is 600torr, Ni-Co alloy powder is used as the catalyst, the arcing discharge current is 80A, the distance between the plates is 120mm, and the low carbon steel plate is the plate base . Set different DC voltages: 9, 18, 36, 54, 72V, and prepare the laser Raman spectrum of single-walled carbon nanotubes, see Figure 5.

Implementation Example 5

Install a consumable anode rod on the anode turntable, the temperature is room temperature, helium atmosphere, the atmosphere pressure is 600torr, Ni-Co alloy powder is used as the catalyst, the arcing discharge current is 80A, the applied DC electric field voltage is 54V, and the low carbon steel plate is used as the electrode. Board base. The distance between the pole plates is 120 mm, and the Raman spectrum of the single-walled carbon nanotubes is prepared, as shown in Figure 6.

Implementation Example 6

The device is shown in Figure 1

Install a consumable anode rod on the anode turntable, the temperature is room temperature, helium atmosphere, the atmosphere pressure is 600torr, Ni-Co alloy powder is used as the catalyst, the arcing discharge current is 80A, the applied DC electric field voltage is 54V, and the distance between the plates is 120mm. The aluminum alloy plate was selected as the plate substrate, and the laser Raman spectrum of the single-walled carbon nanotube was prepared, as shown in Fig. 7 .

Claims (2)

1. An improved temperature-controlled electric arc furnace, including a vacuum container (1), a movable cathode (2), a rotatable anode (5), an electrode feeding system (3) and a temperature-controlling thermocouple (4); its features It also includes a pair of electrode plates (6); a pair of electrode plates are arranged on the upper and lower opposite sides of the heating device of the vacuum vessel (1), and 1 to 6 consumable anodes can be installed on the turntable of the rotatable anode (5) Rod; the hole of the spent anode rod is filled with catalyst and high-purity graphite powder; the cathode is a high-purity graphite rod. 2. a method adopting the improved temperature-controlled electric arc furnace as claimed in claim 1 can controlly prepare semiconducting single-walled carbon nanotubes, it is characterized in that the steps are as follows: Step 1: Adjust the distance between the electrode plates to 3-20cm, and the DC voltage is less than or equal to 300V; Adjust the distance between the electrode plates to cm, and the DC voltage is less than or equal to; Step 2: The catalyst is introduced to be less than or equal to the total amount of 10wt%; the catalyst contains a powder mixture of ferrous sulfide, potassium chloride, ammonium molybdate, and metal nickel, magnesium, cobalt, and iron; Step 3: Under the atmosphere of helium, helium and nitrogen or helium and argon, arc discharge at a current of 50-280A to obtain semiconducting single-walled carbon nanotubes.

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