CN109592668B - Method for controlling diameter of carbon nano tube - Google Patents
Method for controlling diameter of carbon nano tube Download PDFInfo
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- CN109592668B CN109592668B CN201910072490.9A CN201910072490A CN109592668B CN 109592668 B CN109592668 B CN 109592668B CN 201910072490 A CN201910072490 A CN 201910072490A CN 109592668 B CN109592668 B CN 109592668B
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Abstract
The invention belongs to the field of carbon nano tubes, and discloses a method for controlling the diameter of a carbon nano tube, which comprises the following steps: (1) dispersing carbon nano tubes in a solvent, dripping a small amount of supernatant liquid on a heating chip, heating and drying to volatilize the solvent in the supernatant liquid and leave the carbon nano tubes; (2) and heating the carbon nano tube to be more than 800 ℃ by using the heating chip in a vacuum environment, irradiating the carbon nano tube by using electron beams, and continuously reducing the diameter of the carbon nano tube in a nondestructive and controllable manner to enable the carbon nano tube to reach the expected diameter. The method provided by the invention can be used for preparing the carbon nano tube with any specific diameter (smaller than the initial diameter), not only can be used for processing a single carbon nano tube, but also can be used for simultaneously processing a plurality of carbon nano tubes in a large batch, so that the carbon nano tube with the specific diameter and even the minimum diameter can be obtained.
Description
Technical Field
The invention belongs to the field of carbon nanotubes, and particularly relates to a method for controlling the diameter of a carbon nanotube.
Background
Since their first discovery in 1991, carbon nanotubes have attracted extensive attention all over the world due to their unique structures and unusual physicochemical properties. Studies have shown that the physical and chemical properties of a carbon nanotube depend to a large extent on its size and chirality, and that small changes in the chiral index can greatly alter the band structure and electrical properties of the carbon nanotube. Therefore, the preparation of carbon nanotubes with controllable diameter and chirality is extremely critical for the development of various electronic and optoelectronic devices based on carbon nanotubes. In addition, when the carbon nanotube diameter becomes extremely small, the strong curvature effect aggravates the σ and π orbital hybridization, thereby changing the electron state distribution and increasing the electron-phonon coupling, so that the carbon nanotube exhibits some unconventional properties, such as superconducting behavior. Meanwhile, as the diameter of the carbon nanotube is reduced, the carbon nanotube may exhibit mechanical, thermal, and magnetic properties that are distinct from those of a large-diameter carbon nanotube.
In recent years, many researchers have devoted themselves to exploring the minimum diameter of carbon nanotubes using various experimental and theoretical methods, and have made a series of important advances. From the earlier findings of 0.7nm single-walled carbon nanotubes, there is a gradual decrease to smaller single-walled carbon nanotubes of around 0.4nm, which can be even smaller with very few spatial domains, such as 0.3nm diameter observed at the most core of multi-walled carbon nanotubes. There is also a theoretical prediction of the minimum diameter for a simple multi-walled carbon nanotube, i.e., a double-walled carbon nanotube. However, how to prepare the smallest double-walled carbon nanotubes and other few-walled carbon nanotubes lacks relevant experimental studies. One will naturally also curious what is the diameter of the smallest double-or few-walled carbon nanotube? At its smallest diameter, these carbon nanotubes in turn have what unusual physical and chemical properties? Therefore, it is urgently needed to develop a method capable of simply and effectively controlling the diameter of the carbon nanotube to solve the problems of importance and practical application value.
Disclosure of Invention
The present invention aims at providing one new method of controlling the diameter of carbon nanotube.
The method for controlling the diameter of the carbon nano tube comprises the following steps:
(1) dispersing carbon nano tubes in a solvent, dripping a small amount of supernatant liquid on a heating chip, heating and drying to volatilize the solvent in the supernatant liquid and leave the carbon nano tubes;
(2) and under a vacuum environment, heating the carbon nano tube to be more than 800 ℃ by using the heating chip, irradiating the carbon nano tube by using an electron beam, and continuously reducing the diameter of the carbon nano tube in a nondestructive and controllable manner to enable the carbon nano tube to reach the expected diameter.
Preferably, the carbon nanotubes are selected from at least one of single-walled carbon nanotubes, double-walled carbon nanotubes, triple-walled carbon nanotubes and quadruple-walled carbon nanotubes.
Preferably, the solvent is selected from at least one of ethanol, ethylene glycol and acetone. The dispersion conditions are only required to be sufficient to disperse the carbon nanotubes in the solvent, i.e., to be in a dispersed state rather than an aggregated state.
Preferably, the heating and drying temperature is 60-100 ℃.
Preferably, the electron beam irradiation is stopped immediately when the diameter of the carbon nanotube is no longer reduced.
Preferably, in the step (2), the heating temperature is 1000-1200 ℃.
Preferably, in the step (2), the intensity of the electron beam irradiation is 10-100A/cm2。
Preferably, in the step (2), the heating mode is that the dried heating chip is installed on an in-situ heating rod, then the in-situ heating rod is transferred into a transmission electron microscope, temperature control software matched with the in-situ heating rod is started, the heating chip is heated, the temperature of the heating chip is rapidly raised to be above 800 ℃, preferably to be 1000-1200 ℃, and the constant temperature is kept.
Preferably, in the step (2), the electron beam irradiation mode is to calibrate a light path of the transmission electron microscope, select a single or multiple carbon nanotubes on the heating chip as an irradiation object, adjust different magnification factors and electron beam intensities, perform electron beam irradiation on the selected carbon nanotubes, record a diameter change process of the carbon nanotubes, and stop the electron beam irradiation when the carbon nanotubes reach an expected diameter or the diameter is not reduced any more.
The invention adopts the electron beam to irradiate the carbon nano tube under the high temperature condition, so that the diameter of the carbon nano tube is nondestructively, controllably and continuously reduced to the expected diameter or even the minimum diameter, thereby realizing the purpose of accurately controlling the diameter of the carbon nano tube and filling the blank of the existing preparation method of the carbon nano tube with the minimum diameter.
The invention has the following advantages and technical effects:
(1) the method is simple to operate, and can prepare the single-wall, double-wall, three-wall and four-wall carbon nanotubes with the minimum diameter.
(2) The present invention can prepare carbon nanotubes of any specific diameter (smaller than the initial diameter) by controlling the diameter reduction rate of the carbon nanotubes.
(3) The invention can process not only a single carbon nano tube, but also a plurality of carbon nano tubes simultaneously in large batch to obtain the carbon nano tube with a specific diameter or the minimum diameter.
Drawings
FIG. 1 is a schematic view of a process for controlling the diameter of a carbon nanotube according to the present invention;
FIG. 2 is an electron microscope image of any one selected initial double-walled carbon nanotube;
FIG. 3 is an electron microscope image obtained after 10 minutes of heating-irradiating treatment of the double-walled carbon nanotube selected in FIG. 2;
FIG. 4 is an electron microscope image of inner tube fracture and axial shrinkage after the diameter of the double-walled carbon nanotube is reduced to the limit;
FIG. 5 is an electron microscope image of a minimum diameter double-walled carbon nanotube obtained after a long-time heating-irradiation treatment;
FIG. 6 is an electron microscope image of a minimum diameter single-walled carbon nanotube obtained after a long time heating-irradiation treatment;
FIG. 7 is an electron microscope image of a minimum diameter triple-walled carbon nanotube after a long heating-irradiation treatment;
FIG. 8 is an electron microscope image of a minimum-diameter four-walled carbon nanotube obtained after a long-time heating-irradiation treatment;
FIG. 9 is a graph of the outer diameter reduction rate of carbon nanotubes irradiated under the same electron beam irradiation conditions but heated at different temperatures;
FIG. 10 is a graph of the outer diameter reduction rate of carbon nanotubes with the same heating temperature but different electron beam irradiation intensities;
FIG. 11 is an electron micrograph of selected large-area carbon nanotubes;
FIG. 12 is an electron micrograph of the carbon nanotubes enlarged within the black dashed box of FIG. 11;
FIG. 13 is an electron micrograph of the carbon nanotubes within the range of FIG. 12 after 60 minutes of heat-irradiation treatment;
FIG. 14 is an electron microscope image of carbon nanotubes after electron beam irradiation for 10 minutes under a heating condition of 600 ℃.
Detailed Description
The following detailed description of embodiments of the invention is intended to be illustrative of the invention and is not to be construed as limiting the invention. The examples do not specify particular techniques or conditions, and are performed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.
Example 1
This example is provided to illustrate the method of controlling the diameter of carbon nanotubes provided by the present invention.
The carbon nanotubes used in this example were double-walled carbon nanotubes prepared by arc discharge, which also contained a small amount of single-walled carbon nanotubes, triple-walled carbon nanotubes, and quadruple-walled carbon nanotubes.
(1) Firstly, a small amount of carbon nano tube sample (1mg) is put into a centrifugal tube of 1ml, then 0.5ml of glycol solvent is dripped into the centrifugal tube, then the centrifugal tube is put into an ultrasonic cleaning instrument for ultrasonic treatment for 30 minutes, the centrifugal tube is taken out and kept stand for a few minutes, 1.5 mu L of supernatant is taken by a pipette and dripped into a hole groove of a heating chip, and finally the heating chip loaded with the carbon nano tube sample is put into a vacuum drying oven and dried for 30 minutes at 80 ℃.
(2) As shown in fig. 1, the dried heating chip is mounted on the in-situ heating rod, the high-temperature heating is realized by the in-situ heating rod, the in-situ rod heating chip can accurately control the temperature to be +/-0.1 ℃, the maximum heating rate can reach 10 ℃/s, and the maximum heating temperature is 1200 ℃. And then transferring the in-situ heating rod into a transmission electron microscope, starting temperature control software matched with the in-situ heating rod, heating the carbon nano tube, rapidly heating the heating chip to 1200 ℃ at the speed of 10 ℃/s, and keeping the temperature constant. After the temperature is stabilized, the height of the sample stage is adjusted, observation is started by using a transmission electron microscope, a single suspended double-wall carbon nano tube is found, the position of the double-wall carbon nano tube is recorded and photographed, and the obtained result is shown in figure 2. As can be seen from fig. 2, the initial double-walled carbon nanotube selected was measured to have a diameter of 4.32 nm.
Calibrating the light path of the transmission electron microscope, selecting appropriate spot size (generally 1-3), moving the electron beam spot to a blank area under a higher magnification (the magnification selected here is 100 ten thousand times), scattering the spot to the whole fluorescent screen, and adjusting the electron beam irradiation intensity (the electron beam irradiation intensity selected here is 20A/cm)2). And finally, moving the selected initial double-walled carbon nanotube to the center of a fluorescent screen, carrying out electron beam irradiation treatment, and recording the dynamic evolution process of the double-walled carbon nanotube structure by using video software in the irradiation process. As shown in fig. 3, through 10 minutesAfter the heating-irradiation treatment, the initial diameter of the double-wall carbon nano tube is reduced to 2.36nm from 4.32nm, the diameter is reduced by about 45 percent, and the diameter reduction rate is 0.20 nm/min. Continuing long-time irradiation, the diameter of the double-wall carbon nano tube is continuously reduced until the inner tube of the double-wall carbon nano tube is broken and shrinks along the axial direction (as shown in figure 4), and immediately stopping electron beam irradiation to obtain the double-wall carbon nano tube with the minimum diameter (as shown in figure 5). As can be seen from fig. 4 and 5, the inner tube of the double-walled carbon nanotube has been fractured and has undergone axial contraction, indicating that the diameter thereof has been reduced to a minimum limit value, which was measured to have an outer diameter of 1.04nm and an inner diameter of 0.32 nm.
Example 2
This example is provided to illustrate the method of controlling the diameter of carbon nanotubes provided by the present invention.
The carbon nanotubes used in this example were single-walled carbon nanotubes prepared by arc discharge, which also contained a small amount of double-walled carbon nanotubes, triple-walled carbon nanotubes, and quadruple-walled carbon nanotubes.
(1) Firstly, a small amount of carbon nano tube sample (1mg) is put into a centrifugal tube of 1ml, then 0.5ml of glycol solvent is dripped into the centrifugal tube, then the centrifugal tube is put into an ultrasonic cleaning instrument for ultrasonic treatment for 30 minutes, the centrifugal tube is taken out and kept stand for a few minutes, 1.5 mu L of supernatant is taken by a pipette and dripped into a hole groove of a heating chip, and finally the heating chip loaded with the carbon nano tube sample is put into a vacuum drying oven and dried for 30 minutes at 80 ℃.
(2) As shown in fig. 1, the dried heating chip is mounted on the in-situ heating rod, the high-temperature heating is realized by the in-situ heating rod, the in-situ rod heating chip can accurately control the temperature to be +/-0.1 ℃, the maximum heating rate can reach 10 ℃/s, and the maximum heating temperature is 1200 ℃. And then transferring the in-situ heating rod into a transmission electron microscope, starting temperature control software matched with the in-situ heating rod, heating the carbon nano tube, rapidly heating the heating chip to 1000 ℃ at the speed of 10 ℃/s, and keeping the temperature constant. After the temperature is stable, the height of the sample stage is adjusted, observation is started by using a transmission electron microscope, a single suspended single-walled carbon nanotube is found, the position of the single-walled carbon nanotube is recorded, and a picture is taken. The diameter of the selected initial single-walled carbon nanotube is 1.74nm through measurement.
Calibrating the light path of the transmission electron microscope, selecting appropriate spot size (generally 1-3), moving the electron beam spot to a blank area under a higher magnification (the magnification selected here is 100 ten thousand times), scattering the spot to the whole fluorescent screen, and adjusting the electron beam irradiation intensity (the electron beam irradiation intensity selected here is 30A/cm)2). And finally, moving the selected initial single-walled carbon nanotube to the center of a fluorescent screen, carrying out electron beam irradiation treatment, and recording the dynamic evolution process of the single-walled carbon nanotube structure by using video software in the irradiation process. After 2 minutes of heating-irradiation treatment, the initial diameter of the single-walled carbon nanotube is reduced to 0.70nm, about 60 percent, and the diameter reduction rate is 0.52 nm/min. Continuing to irradiate for a long time, the diameter of the single-walled carbon nanotube will be reduced continuously until the single-walled carbon nanotube is not reduced, and immediately stopping the electron beam irradiation to obtain the single-walled carbon nanotube with the minimum diameter (as shown in fig. 6). As can be seen from fig. 6, the diameter of the smallest single-walled carbon nanotube obtained by the present invention is 0.43nm, which is consistent with the diameter of the smallest single-walled carbon nanotube reported so far, and illustrates the reliability of the method for controlling the diameter of the carbon nanotube provided by the present invention.
Example 3
This example is provided to illustrate the method of controlling the diameter of carbon nanotubes provided by the present invention.
The carbon nanotubes used in this example were triple-walled carbon nanotubes prepared by arc discharge, which also contained a small amount of single-walled carbon nanotubes, double-walled carbon nanotubes, and quadruple-walled carbon nanotubes.
(1) Firstly, a small amount of carbon nano tube sample (1mg) is put into a centrifugal tube of 1ml, then 0.5ml of glycol solvent is dripped into the centrifugal tube, then the centrifugal tube is put into an ultrasonic cleaning instrument for ultrasonic treatment for 30 minutes, the centrifugal tube is taken out and kept stand for a few minutes, 1.5 mu L of supernatant is taken by a pipette and dripped into a hole groove of a heating chip, and finally the heating chip loaded with the carbon nano tube sample is put into a vacuum drying oven and dried for 30 minutes at 80 ℃.
(2) As shown in fig. 1, the dried heating chip is mounted on the in-situ heating rod, the high-temperature heating is realized by the in-situ heating rod, the in-situ rod heating chip can accurately control the temperature to be +/-0.1 ℃, the maximum heating rate can reach 10 ℃/s, and the maximum heating temperature is 1200 ℃. And then transferring the in-situ heating rod into a transmission electron microscope, starting temperature control software matched with the in-situ heating rod, and heating the carbon nano tube to ensure that the heating chip is quickly heated to 1100 ℃ at the speed of 10 ℃/s and is kept constant. After the temperature is stable, the height of the sample stage is adjusted, observation is started by using a transmission electron microscope, an independent suspended three-wall carbon nano tube is found, the position of the independent suspended three-wall carbon nano tube is recorded, and a picture is taken. The diameter of the selected initial three-wall carbon nano tube is 3.37nm through measurement.
Calibrating the light path of the transmission electron microscope, selecting appropriate spot size (generally 1-3), moving the electron beam spot to a blank area under a higher magnification (the magnification selected here is 100 ten thousand times), scattering the spot to the whole fluorescent screen, and adjusting the electron beam irradiation intensity (the electron beam irradiation intensity selected here is 35A/cm)2). And finally, moving the selected initial three-wall carbon nano tube to the center of a fluorescent screen, carrying out electron beam irradiation treatment, and recording the dynamic evolution process of the three-wall carbon nano tube structure by using video software in the irradiation process. After 5 minutes of heating-irradiation treatment, the three-wall carbon nano tube is reduced to 1.93nm from the initial diameter of 3.37nm, about 43 percent, and the diameter reduction rate is 0.29 nm/min. And continuing long-time irradiation, the diameter of the three-wall carbon nanotube is continuously reduced until the inner tube of the three-wall carbon nanotube is broken and shrinks along the axial direction, and immediately stopping electron beam irradiation to obtain the three-wall carbon nanotube with the minimum diameter (as shown in figure 7). As can be seen from FIG. 7, the minimum triple-walled carbon nanotube obtained by the present invention has an outer diameter of 1.66nm and an inner diameter of 0.32 nm.
Example 4
This example is provided to illustrate the method of controlling the diameter of carbon nanotubes provided by the present invention.
The carbon nanotubes used in this example were four-walled carbon nanotubes prepared by arc discharge, which also contained a small amount of single-walled carbon nanotubes, double-walled carbon nanotubes, and three-walled carbon nanotubes.
(1) Firstly, a small amount of carbon nano tube sample (1mg) is put into a centrifugal tube of 1ml, then 0.5ml of glycol solvent is dripped into the centrifugal tube, then the centrifugal tube is put into an ultrasonic cleaning instrument for ultrasonic treatment for 30 minutes, the centrifugal tube is taken out and kept stand for a few minutes, 1.5 mu L of supernatant is taken by a pipette and dripped into a hole groove of a heating chip, and finally the heating chip loaded with the carbon nano tube sample is put into a vacuum drying oven and dried for 30 minutes at 80 ℃.
(2) As shown in fig. 1, the dried heating chip is mounted on the in-situ heating rod, the high-temperature heating is realized by the in-situ heating rod, the in-situ rod heating chip can accurately control the temperature to be +/-0.1 ℃, the maximum heating rate can reach 10 ℃/s, and the maximum heating temperature is 1200 ℃. And then transferring the in-situ heating rod into a transmission electron microscope, starting temperature control software matched with the in-situ heating rod, heating the carbon nano tube, rapidly heating the heating chip to 1100 ℃ at the speed of 10 ℃/s, and keeping the temperature constant. And after the temperature is stable, adjusting the height of the sample stage, observing by using a transmission electron microscope, finding an independent suspended four-wall carbon nanotube, recording the position of the carbon nanotube and taking a picture. The diameter of the selected initial four-wall carbon nano tube is 5.73nm through measurement.
Calibrating the light path of the transmission electron microscope, selecting appropriate spot size (generally 1-3), moving the electron beam spot to a blank area under a higher magnification (the magnification selected here is 100 ten thousand times), scattering the spot to the whole fluorescent screen, and adjusting the electron beam irradiation intensity (the electron beam irradiation intensity selected here is 50A/cm)2). And finally, moving the selected initial four-wall carbon nano tube to the center of a fluorescent screen, carrying out electron beam irradiation treatment, and recording the dynamic evolution process of the four-wall carbon nano tube structure by using video software in the irradiation process. After 5 minutes of heating-irradiation treatment, the initial diameter of the four-wall carbon nano tube is reduced to 4.23nm from 5.73nm, about 26 percent, and the diameter reduction rate is 0.3 nm/min. Continuing long-time irradiation, the diameter of the four-wall carbon nanotube will be reduced continuously until the inner tube of the four-wall carbon nanotube is broken and contracted along the axial direction, and immediately stopping electron beam irradiation to obtain the four-wall carbon nanotube with the minimum diameter (as shown in fig. 8). From FIG. 8, it can be seen that the minimum obtained by the present inventionThe outer diameter of the four-wall carbon nano tube is 2.41nm, and the inner diameter is 0.32 nm.
From the above results, it can be seen that the method provided by the present invention can prepare not only the minimum diameter double-wall carbon nanotubes, but also the minimum diameter single-wall carbon nanotubes, triple-wall carbon nanotubes and quadruple-wall carbon nanotubes, i.e., the minimum diameter carbon nanotubes with the number of walls of 4 or less. In addition, the heating temperature and the electron beam irradiation intensity are two major factors affecting the nondestructive continuous reduction rate of the carbon nanotube: under the same electron beam irradiation intensity, the higher the heating temperature is, the faster the nondestructive reduction rate of the carbon nano tube is; under the same heating temperature, the higher the irradiation intensity of the electron beam, the faster the nondestructive reduction rate of the carbon nano tube. Therefore, the carbon nano tube with any specific diameter (the specific diameter is smaller than the initial diameter) can be controllably prepared by adjusting the heating temperature and the irradiation intensity of the electron beam.
Example 5
This example is provided to illustrate the method of controlling the diameter of carbon nanotubes provided by the present invention.
The diameter of the carbon nanotubes was controlled as in example 1, except that the in-situ rod heated chip was heated to 1000 ℃ and the other conditions were the same as in example 1. The result shows that the diameter of the double-wall carbon nano tube is continuously reduced along with the extension of the irradiation time of the electron beam until the inner tube of the double-wall carbon nano tube is broken and shrinks along the axial direction, and the irradiation of the electron beam is immediately stopped, thus obtaining the double-wall carbon nano tube with the minimum diameter.
Example 6
This example is provided to illustrate the method of controlling the diameter of carbon nanotubes provided by the present invention.
The diameter of the carbon nanotubes was controlled according to the method of example 1, except that the in-situ rod heated chip was heated to 800 deg.C, and the rest of the conditions were the same as in example 1. The result shows that the diameter of the double-wall carbon nano tube is continuously reduced along with the extension of the irradiation time of the electron beam until the inner tube of the double-wall carbon nano tube is broken and shrinks along the axial direction, and the irradiation of the electron beam is immediately stopped, thus obtaining the double-wall carbon nano tube with the minimum diameter. In addition, the results of the change in the diameter of the carbon nanotube with the increase in the electron beam irradiation time in example 1, example 5 and example 6 are shown in fig. 9. As can be seen from FIG. 9, the reduction rates of the double-walled carbon nanotube at 800 deg.C, 1000 deg.C, 1200 deg.C are 0.07nm/min, 0.13nm/min, 0.20nm/min, respectively, under the same electron beam irradiation intensity, which indicates that the higher the heating temperature is, the faster the nondestructive reduction rate of the carbon nanotube is.
Example 7-example 9
Examples 7 to 9 are provided to illustrate the method of controlling the diameter of carbon nanotubes provided by the present invention.
The diameter of the carbon nanotube was controlled in the same manner as in example 1, except that the intensity of the electron beam irradiation was replaced with 75A/cm, respectively2、45A/cm2And 15A/cm2The other conditions were the same as in example 1, and the results are shown in FIG. 10. As can be seen from FIG. 10, the double-walled carbon nanotube was at 15A/cm at the same heating temperature2、45A/cm2、75A/cm2The reduction rates under the irradiation intensity of the electron beams are respectively 0.11nm/min, 0.42nm/min and 0.67nm/min, which shows that the higher the irradiation intensity of the electron beams is, the faster the nondestructive reduction rate of the carbon nano tube is.
Example 10
This example is provided to illustrate the method of controlling the diameter of carbon nanotubes provided by the present invention.
The diameter of the carbon nanotube was controlled in the same manner as in example 1, except that the magnification of the transmission electron microscope was adjusted to 1.1 ten thousand times and the irradiation intensity of the electron beam was adjusted to 12A/cm2The results obtained are shown in FIGS. 11 to 13, as in example 1. Fig. 11 is an electron micrograph of a selected large-area carbon nanotube, fig. 12 is an electron micrograph of a carbon nanotube enlarged in a black dotted square in fig. 11, and fig. 13 is an electron micrograph of a carbon nanotube within the range of fig. 12 after heating-irradiation treatment for 60 minutes. From the results of fig. 11-13, it can be seen that all the double-walled carbon nanotubes in the field of view are reduced after long-term heating and electron beam irradiation treatment, which indicates that a plurality of carbon nanotubes (> 1000) can be processed in batch by the method provided by the present invention.
Comparative example 1
This comparative example is used to illustrate a reference method of controlling the diameter of carbon nanotubes.
The diameter of the carbon nanotubes was controlled according to the method of example 1, except that the in-situ rod heated chip was heated to 600 ℃ under the same conditions as in example 1, and the results are shown in FIG. 14. As can be seen from fig. 14, the diameter of the double-walled carbon nanotube may be reduced as the electron beam irradiation time is prolonged, but is not reduced without damage. Due to the low heating temperature, the electron beam irradiation may cause defects, such as twisting, to the carbon nanotubes.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (7)
1. A method for controlling the diameter of carbon nanotubes, wherein said carbon nanotubes are produced by an arc discharge process, comprising the steps of:
(1) dispersing carbon nano tubes in a solvent, dripping a small amount of supernatant liquid on a heating chip, heating and drying to volatilize the solvent in the supernatant liquid and leave the carbon nano tubes;
(2) under the vacuum environment, the carbon nano tube is heated to be more than 800 ℃ by utilizing the heating chip, then the carbon nano tube is irradiated by utilizing the electron beam, and the diameter of the carbon nano tube is reduced continuously in a nondestructive and controllable way to reach the expected diameter;
in the step (2)The intensity of the electron beam irradiation is 15-100A/cm2；
In the step (2), the heating mode is that the dried heating chip is installed on the in-situ heating rod, then the in-situ heating rod is transferred into the transmission electron microscope, temperature control software matched with the in-situ heating rod is started, the heating chip is heated, the temperature of the heating chip is rapidly raised to be above 800 ℃, and the constant temperature is kept.
2. The method of controlling the diameter of carbon nanotubes as claimed in claim 1, wherein said carbon nanotubes are selected from at least one of single-walled carbon nanotubes, double-walled carbon nanotubes, triple-walled carbon nanotubes and quadruple-walled carbon nanotubes.
3. The method for controlling the diameter of carbon nanotubes according to claim 1, wherein the solvent is at least one selected from the group consisting of ethanol, ethylene glycol and acetone.
4. The method for controlling the diameter of carbon nanotubes according to claim 1, wherein the temperature of the heat drying is 60 to 100 ℃.
5. The method of controlling the diameter of carbon nanotubes according to any of claims 1 to 4, wherein the electron beam irradiation is stopped immediately when the diameter of the carbon nanotubes is no longer reduced.
6. The method for controlling the diameter of carbon nanotubes according to any one of claims 1 to 4, wherein the heating temperature in the step (2) is 1000 to 1200 ℃.
7. The method for controlling the diameter of carbon nanotubes of claim 1, wherein in step (2), the electron beam irradiation is performed by calibrating the optical path of the transmission electron microscope, selecting one or more carbon nanotubes on the heating chip as the irradiation target, adjusting the different magnification and the intensity of the electron beam, performing the electron beam irradiation on the selected carbon nanotubes, recording the diameter variation process of the carbon nanotubes, and stopping the electron beam irradiation when the carbon nanotubes reach the desired diameter or the diameter is not reduced.
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| CN111115562B (en) * | 2019-12-13 | 2023-03-10 | 华东师范大学 | Method for in-situ processing of hollow nanometer cavity |
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