CN101481788A - Preparation of single wall carbon nano-tube film - Google Patents

Abstract

The invention discloses a preparation method of a single-wall carbon nanotube film. It is made of metal molybdenum powder, metal iron powder, nickel powder, yttrium powder, cobalt powder, etc. in a certain proportion to form a binary or three-way catalyst, and then fill it into a Φ6×50mm graphite rod to form a composite graphite anode, and install it in the arc discharge In the device, the molar percentage of molybdenum powder is 0.1%-2%, and the molar percentage of other metals is 0.5%-5%. A mixed gas of hydrogen and argon (pressure ratio 2:3, total pressure 150-250 Torr) or helium (pressure 150-250 Torr) is used. The discharge current of the composite graphite anode is 50-100A, the arc discharge is 5-100 seconds, and the single-walled carbon nanotube film can be obtained on the upper spherical cathode graphite plate in the arc discharge device, and the conversion rate reaches 90%. above. The area of the prepared film can reach more than 100-230 cm ² , the thickness of the film is between several micrometers and 1 millimeter, and the film has certain directionality.

Description

Preparation method of single-walled carbon nanotube film

technical field

The invention relates to a preparation method of a single-wall carbon nanotube film.

Background technique

Single-walled carbon nanotubes (SWCNTs) prepared by arc discharge method have the characteristics of good crystallinity and short preparation time. However, this method also has the disadvantages of low yield and poor purity. With the continuous development of carbon nanotube research, many applications require a large amount of high-purity single-walled carbon nanotubes. In the history of more than ten years of preparation of single-walled carbon nanotubes by the arc discharge method, various metal catalysts have been used for the preparation of single-walled carbon nanotubes. However, the catalytic efficiency of these catalysts is not very high. Therefore, it is difficult for the arc discharge method to meet the needs of mass production of high-quality single-walled carbon nanotubes.

The existing research results show that, because of its perfect structure, single-walled carbon nanotubes can become a new type of material with excellent mechanical, electrical and other properties, and have very broad applications in many fields. Application prospects. Making single-walled carbon nanotubes into large-area films plays an important role in exerting their various excellent properties. Especially in composite materials, field emission materials, catalytic electrode membranes of fuel cells, etc., there is an urgent need for large-area, high-purity, high-quality single-walled carbon nanotube films, and they have certain directionality.

Contents of the invention

The purpose of the present invention is to provide a preparation method of single-walled carbon nanotube film.

A preparation method of a single-walled carbon nanotube film is to fill molybdenum powder and iron powder into a Φ6×50mm graphite rod to form a composite graphite anode, and install it in an arc discharge device. The molar percentage of the molybdenum powder is 0.1% to 1 %, the molar percentage of iron powder is 0.2-1.6%, the mixed gas of hydrogen and argon is used, the pressure ratio of hydrogen and argon is 2:3, and the total pressure is 150-250Torr, the discharge current of the composite graphite anode is 70-100A, arc discharge for 5-30 seconds, and a very thin single-wall carbon nanotube film is collected on the cathode of the upper spherical cathode graphite plate in the arc discharge device.

Another preparation method of single-wall carbon nanotube film is to fill molybdenum powder, nickel powder and yttrium powder into a graphite rod of Φ6×50mm to form a composite graphite anode, and install it in an arc discharge device. The molar percentage of molybdenum powder is 0.1% to 1%, the molar percentage of nickel powder is 2% to 5%, the molar percentage of yttrium powder is 0.5% to 1.3%, using helium, and the pressure of helium is 300 to 600 Torr, the composite graphite anode discharge The current is 50-80A, the arc discharge is 30-100 seconds, and the single-wall carbon nanotube film is collected on the cathode of the upper spherical cathode graphite plate in the arc discharge device.

Another preparation method of single-walled carbon nanotube film is to fill molybdenum powder and cobalt powder into a graphite rod of Φ6×50mm to form a composite graphite anode, and install it in an arc discharge device. The molar percentage of molybdenum powder is 0.1%～ 1.6%, the molar percentage of cobalt powder is 0.3%~2%, using argon, the pressure of argon is 150~300Torr, the composite graphite anode discharge current is 50~80A, and the arc discharge is 30~100 seconds. The single-walled carbon nanotube film is collected on the cathode of the upper spherical cathode graphite plate in the discharge device.

The invention uses metal molybdenum (Mo) as the core component of the catalyst and combines it with other traditional metal catalysts in a certain proportion to form a novel catalyst with high efficiency. Add these different metal catalysts to the graphite electrode rod according to a fixed ratio to make a catalyst composite electrode, which is installed on the anode in the vacuum chamber of the arc discharge equipment. The vacuum chamber is installed in the vacuum chamber under a certain pressure of inert gas atmosphere. An arc discharge is performed on the graphite rod at the cathode. Single-walled carbon nanotube films can be obtained on the cathode graphite electrode plate in a special device consisting of two spherical-capped cathode graphite plates. The preparation method of the single-wall carbon nanotube has the characteristics of simple process, less investment, high efficiency (the conversion rate reaches more than 90%) and the like. In addition, the prepared single-wall carbon nanotubes have good quality and high purity, and the thickness of the single-wall carbon nanotube film can be controlled as required. The feature of the invention is that very thin single-wall carbon nanotube film can be prepared, and the thin film can reach several micrometers, or even thinner. Moreover, the prepared single-wall carbon nanotube film has a large area (100-230 cm ² ), and the distribution of the single-wall carbon nanotube has a certain directionality.

Description of drawings

Fig. 1 is the structural representation of the single-walled carbon nanotube film device prepared by arc discharge method;

Figure 2 is a scanning electron micrograph of the single-walled carbon nanotubes prepared by using molybdenum powder and iron powder binary catalyst in Example 1. There are a large number of single-walled carbon nanotube bundles on the surface of the film, and they have certain directionality, and there are also some catalyst particles;

Figure 3 is a high-magnification photo of the scanning electron microscope of Figure 2, a large number of single-walled carbon nanotube bundles are clearly visible;

Fig. 4 is the Raman spectrogram (excitation wavelength is 514.5nm at room temperature) of single-walled carbon nanotube thin film in embodiment 1. From the comparison of the intensity of the amorphous carbon peak at 1334cm ^-1 and the characteristic peak intensity of single-walled carbon nanotubes near 1587cm ^-1 , it can be seen that the single-walled carbon nanotube film contains only a small amount of amorphous carbon, and the low frequency range is 150-210cm ^-1 The peak value of the breathing vibrating membrane can be calculated to have an average diameter of single-walled carbon nanotubes of 1.28nm;

Detailed ways

As shown in Figure 1, the device for preparing single-walled carbon nanotube films by the arc discharge method comprises an arc discharge vacuum chamber 3, the arc discharge vacuum chamber is connected with a vacuum pump 6, and the arc discharge vacuum chamber is provided with a graphite cathode 5 and a graphite anode 4 , the graphite cathode and the graphite anode are connected with the DC power supply 7, and one of its characteristics is that an upper spherical cap-shaped graphite plate 1 and a lower spherical cap-shaped graphite plate 2 are respectively installed on the graphite cathode 5 and the graphite anode 4, single-walled carbon nanotubes The thin film is formed on the upper spherical graphite plate 1 .

The present invention prepares the single-walled carbon nanotube thin film device based on the arc discharge method, and installs a pair of upper spherical cap graphite plates and lower spherical cap graphite plates respectively on the graphite cathode and the graphite anode to form a spherical cap capacitor (comprising flat plates) type capacitor) device to achieve the goal of preparing large-area, high-quality single-walled carbon nanotube films. The feature of the invention is that the arc discharge of the cathode graphite rod and the anode graphite rod containing high-efficiency metal catalyst is carried out in the space formed by two spherical crown type graphite pole plates. During the discharge process, since there is always an electric field between the two spherical-capped graphite plates, the spherical-capped graphite cathode plate at negative potential has the property of attracting carbon ions. On the other hand, due to the space formed by the two spherical cap-shaped graphite plates, the diffusion form of carbon ions and the like is changed, and the synthesis probability of single-walled carbon nanotubes is increased. At the same time, in the vacuum chamber filled with an inert gas atmosphere and a certain pressure, the high temperature generated by the arc discharge evaporates the graphite anode rod containing the metal catalyst. At this time, the carbon ions are synthesized due to the action of the electric field and the specific gas diffusion form The carbon nanotubes are in the form of a uniform film, almost completely attached to the inner surface of the upper spherical graphite cathode plate. This single-walled carbon nanotube film has the characteristics of large area (100-200cm ² ) and high purity, and the thickness of the single-walled carbon nanotube film can also be controlled according to needs, and the film thickness is on the order of several microns to 1 mm between. Field emission scanning electron microscopy (FSEM) and Raman (Raman) spectrum research and testing show that the conversion rate of the prepared single-walled carbon nanotubes has reached 90% to the single-walled carbon nanotube film samples synthesized in the examples Above, the average diameter is 1.28 nm, and the length is on the order of several microns. The electron microscope photos and test curves are shown in attached drawings 2-4.

The experimental conditions for preparing single-walled carbon nanofilms are to combine Mo with one or two or more of Fe, Co, Ni, Y, and two or more catalysts, mix them into a uniform powder in proportion, and mix them into a uniform powder in a certain proportion. Mix it with graphite powder, fill it into a graphite rod with a diameter of 6mm to prepare a composite graphite anode, and use a graphite rod with a diameter of 8mm for the cathode, or directly use a circular arc-shaped graphite plate cathode. The ambient gas is high-purity He gas or a mixed gas of hydrogen and argon, the pressure is between 100-600 Torr, and the current through the anode is between 50-100A. After the graphite cathode and anode electrodes are arc-discharged in the space formed by the spherical cap capacitor, a single-wall carbon nanotube film is formed on the inner surface of the upper spherical cap cathode graphite plate.

Example 1:

Use molybdenum (Mo) powder and iron (Fe) powder binary catalyst, fill 0.2mol% molybdenum and 1mol% iron into a graphite rod of Φ6×50mm, use it as a composite graphite anode, discharge current is 70A, Using a mixed gas of hydrogen and argon, the pressure ratio is 2:3, and the total pressure is 250 Torr, and the arc discharge is carried out for 45 seconds, and a mass of 5.6 mg, Single-walled carbon nanotube films with an area of up to 50 cm ² (thickness of hundreds of microns).

Example 2:

Use molybdenum (Mo) powder and iron (Fe) powder binary catalyst, fill 0.2mol% molybdenum and 1mol% iron into a graphite rod of Φ6×50mm, use it as a composite graphite anode, discharge current is 70A, Using a mixture of hydrogen and argon with a pressure ratio of 2:3 and a total pressure of 200 Torr, arc discharge was carried out for 30 seconds, and a mass of 5 mg and an area of 40 cm ² was collected on the arc-shaped graphite plate cathode. Single-walled carbon nanotube thin film (thickness of about hundreds of microns).

Example 3

Use molybdenum (Mo) powder and iron (Fe) powder binary catalyst, fill 0.2mol% molybdenum and 1mol% iron into a graphite rod of Φ6×50mm, use it as a composite graphite anode, discharge current is 70A, The mixed gas of hydrogen and argon is used, the pressure ratio of hydrogen and argon is 2:3, and the total pressure is 150Torr. The discharge current of the composite graphite anode is 70A, and the arc discharge is 90 seconds. The upper ball in the arc discharge device 9.8 mg of single-walled carbon nanotube films with an area of 180 cm ² were collected on the cathode of the crown-shaped cathode graphite plate.

Example 4

Using molybdenum (Mo) powder, nickel (Ni) powder and yttrium (Y) powder three-way catalyst, 0.2mol% molybdenum powder, 0.8mol% nickel powder and 0.2mol% yttrium powder are filled into a Φ6×50mm graphite rod to form Composite graphite anode, and installed in the arc discharge device, using helium, under the condition of the pressure of 300Torr, the discharge current of the composite graphite anode is 50A, the arc discharge is 100 seconds, the upper spherical crown cathode graphite in the arc discharge device 110 mg of ^single -walled carbon nanotube films with an area of 80 cm were collected on the cathode plate.

Example 5

Using molybdenum (Mo) powder, nickel (Ni) powder and yttrium (Y) powder three-way catalyst, 0.2mol% molybdenum powder, 0.8mol% nickel powder and 0.2mol% yttrium powder are filled into a Φ6×50mm graphite rod to form Composite graphite anode, and installed in the arc discharge device, using helium, under the condition of the pressure of 300Torr, the discharge current of the composite graphite anode is 70A, arc discharge for 50 seconds, the upper spherical crown cathode graphite electrode in the arc discharge device 68 mg of single-walled carbon nanotube films with an area of ¹⁰⁰ cm were collected on the plate cathode.

Example 6

Using molybdenum (Mo) powder, nickel (Ni) powder and yttrium (Y) powder three-way catalyst, 0.2mol% molybdenum powder, 0.8mol% nickel powder and 0.2mol% yttrium powder are filled into a Φ6×50mm graphite rod to form Composite graphite anode, and installed in the arc discharge device, using helium, under the condition of the pressure of 600Torr, the discharge current of the composite graphite anode is 80A, arc discharge for 30 seconds, the upper spherical crown cathode graphite electrode in the arc discharge device 78 mg single-walled carbon nanotube films with an area of 120 cm ² were collected on the plate cathode.

Example 7

Use molybdenum (Mo) powder and cobalt (Co) powder binary catalyst, fill 0.2mol% molybdenum powder and 0.4mol% cobalt powder into a graphite rod of Φ6×50mm to form a composite graphite anode, and install it in an arc discharge device, Adopt argon gas, under the condition that the pressure of argon gas is 300Torr, the composite graphite anode discharge current is 60A, arc discharge is 30 seconds, and 5.5mg is collected on the upper spherical cathode graphite pole plate cathode in the arc discharge device, and the area reaches 60 cm ² single-walled carbon nanotube film.

Example 8

Use molybdenum (Mo) powder and cobalt (Co) powder binary catalyst, fill 0.2mol% molybdenum powder and 0.4mol% cobalt powder into a graphite rod of Φ6×50mm to form a composite graphite anode, and install it in an arc discharge device, Adopt argon gas, under the condition that the pressure of argon gas is 600Torr, the composite graphite anode discharge current is 80A, and arc discharge is 100 seconds, and 11.3mg is collected on the cathode of the upper spherical cathode graphite plate in the arc discharge device, and the area reaches Above 110cm ² , single-walled carbon nanotube film with a thickness of hundreds of microns.

Claims (3)

1. preparation method of single-walled carbon nanotube film, it is characterized in that, molybdenum powder and iron powder are packed in the graphite rod of Φ 6 * 50mm and form the composite graphite anode, and be installed in the arc discharge device, the molecular fraction of molybdenum powder is 0.1%～1%, the molecular fraction of iron powder is 0.2～1.6%, adopt the mixed gas of hydrogen and argon gas, hydrogen and argon pressure are than being 2:3, total pressure is under the condition of 150～250Torr, composite graphite anodic discharging current is 70～100A, and arc-over 5～30 seconds can obtain single wall carbon nano-tube film on the spherical graphite cathode in arc discharge device.

2. preparation method of single-walled carbon nanotube film, it is characterized in that, with molybdenum powder, nickel powder and yttrium powder are packed into the interior composite graphite anode that forms of graphite rod of Φ 6 * 50mm, and be installed in the arc discharge device, the molecular fraction of molybdenum powder is 0.1%～1%, the molecular fraction of nickel powder is 2%～5%, the molecular fraction of yttrium powder is 0.5%～1.3%, adopt helium, under the condition of the pressure 300～600Torr of helium, composite graphite anode discharge electric current is 50～80A, and arc-over 30～100 seconds is collected on the spherical negative electrode graphite pole plate negative electrode in arc discharge device and obtained single wall carbon nano-tube film.

3. preparation method of single-walled carbon nanotube film, it is characterized in that, molybdenum powder and cobalt powder are packed in the graphite rod of Φ 6 * 50mm and form the composite graphite anode, and be installed in the arc discharge device, the molecular fraction of molybdenum powder is 0.1%～1.6%, the molecular fraction of cobalt powder is 0.3%～2%, adopt argon gas, the pressure of argon gas is under the condition of 300～600Torr, composite graphite anode discharge electric current is 50～80A, arc-over 20～100 seconds is collected on the spherical negative electrode graphite pole plate negative electrode in arc discharge device and is obtained single wall carbon nano-tube film.

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