Method for processing carbon nanotubes and carbon nanotubes

Abstract

The embodiment of the present application relates to a kind of carbon nanotube processing method and carbon nanotube.The processing method of carbon nanotube includes: under inert atmosphere, initial carbon nanotube is microwave treated;Microwave treatment includes: initial carbon nanotube is heated to preset temperature using microwave;At preset temperature, initial carbon nanotube is subjected to microwave impact treatment for preset time;Wherein, preset temperature is 600 DEG C-1500 DEG C.Such, the specific surface area of carbon nanotube can be effectively improved, while the surface structure of carbon nanotube is not destroyed.

Description

Technical Field

[0001] This invention relates to the field of carbon nanotube technology, and in particular to a method for processing carbon nanotubes and carbon nanotubes. Background Technology

[0002] Carbon nanotubes are hollow tubes with a honeycomb-like wall structure composed of hexagonally arranged carbon atoms. They possess low density, high electrical conductivity, and high mechanical properties, making them a representative material in the field of nanoscience. Their multifunctional properties play a crucial role in translating into practical applications for economic development. Oligowalled carbon nanotubes (including single-walled and double-walled carbon nanotubes) exhibit excellent electrical conductivity, along with a high aspect ratio and good flexibility. Single-walled carbon nanotubes, in particular, possess superior electrical and electronic properties. Their quasi-one-dimensional structure and high specific surface area enable more effective interactions on the carbon nanotube surface, combining metallic or semiconductor characteristics, attracting significant attention from markets such as high-end digital batteries, new energy vehicle power batteries, and plastic products.

[0003] Many applications of carbon nanotubes (CNTs) heavily rely on the surface area accessible to them. Therefore, breaking up CNT bundles and increasing their specific surface area is a crucial means of expanding their applications. Due to van der Waals forces, multiple CNTs tend to agglomerate into bundles, creating impenetrable "dead zones" and reducing the accessible surface area. To maximize the performance advantages of CNTs, they need to be broken up from their agglomerated state before use. Current methods for breaking up CNT bundles include etching, annealing, and milling. However, these methods are not ideal, failing to significantly increase the specific surface area and potentially damaging the surface structure of the CNTs. Summary of the Invention

[0004] In view of this, the present application provides a method for processing carbon nanotubes and carbon nanotubes to solve at least one problem existing in the background art.

[0005] In a first aspect, embodiments of this application provide a method for processing carbon nanotubes, the method comprising:

[0006] Initial carbon nanotubes are subjected to microwave treatment under an inert atmosphere; the microwave treatment includes:

[0007] The initial carbon nanotubes were heated to a preset temperature using microwaves.

[0008] The initial carbon nanotubes are subjected to microwave shock treatment for a preset time at the preset temperature.

[0009] The preset temperature is 600℃-1500℃.

[0010] In conjunction with the first aspect of this application, in an alternative embodiment, the preset time is less than or equal to 60 minutes.

[0011] In conjunction with the first aspect of this application, in an optional embodiment, the preset time is 10 min to 30 min.

[0012] In conjunction with the first aspect of this application, in an optional embodiment, the preset temperature is 800℃-1000℃.

[0013] In conjunction with the first aspect of this application, in an optional embodiment, during the process of heating the initial carbon nanotubes to a preset temperature using microwaves, the heating rate is 200℃ / min-320℃ / min.

[0014] In conjunction with the first aspect of this application, in an alternative embodiment, the inert atmosphere is argon or nitrogen.

[0015] In conjunction with the first aspect of this application, in an alternative embodiment, the inert atmosphere is argon.

[0016] In conjunction with the first aspect of this application, in an optional embodiment, the initial carbon nanotubes are oligowalled carbon nanotubes, and the specific surface area of ​​the initial carbon nanotubes is less than 840 m². 2 / g; the proportion of initial carbon nanotubes with a tube diameter less than or equal to 10nm in the initial carbon nanotubes is less than 20%.

[0017] In conjunction with the first aspect of this application, in an optional embodiment, after subjecting the initial carbon nanotubes to microwave shock treatment for a preset time, the resulting carbon nanotubes have a specific surface area greater than or equal to 930 m². 2 / g; the proportion of carbon nanotubes with a bundle diameter of less than or equal to 10nm in the obtained carbon nanotubes is greater than or equal to 40%.

[0018] Secondly, embodiments of this application provide a carbon nanotube, which is prepared using the steps of the carbon nanotube processing method described in any of the preceding first aspects.

[0019] The carbon nanotube processing method and carbon nanotubes provided in this application involve microwave treatment of initial carbon nanotubes under an inert atmosphere. The microwave treatment includes: heating the initial carbon nanotubes to a preset temperature using microwaves; and subjecting the initial carbon nanotubes to microwave shock treatment for a preset time at the preset temperature. The preset temperature is 600℃-1500℃. Thus, under the protection of an inert atmosphere, microwave treatment of the initial carbon nanotubes at a temperature of 600℃-1500℃ excites the outer electrons of the initial carbon nanotubes. Utilizing the electrostatic interactions between the carbon nanotubes, the carbon nanotubes gradually dissociate from their aggregated state, forming more and finer carbon nanotube bundles. This effectively increases the specific surface area of ​​the carbon nanotubes while ensuring that the surface structure of the carbon nanotubes is not damaged. Furthermore, the carbon nanotube processing method provided in this application is simple to operate, low in cost, and widely applicable.

[0020] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0022] Figure 1 A schematic flowchart illustrating a method for processing carbon nanotubes provided in an embodiment of this application;

[0023] Figure 2 A scanning electron microscope image of initial carbon nanotubes containing oligowalled carbon nanotubes;

[0024] Figure 3 This is a scanning electron microscope image of the carbon nanotubes obtained after microwave shock treatment for 1 min in Example 2;

[0025] Figure 4 This is a scanning electron microscope image of the carbon nanotubes obtained after microwave shock treatment for 30 min in Example 2;

[0026] Figure 5 This is a scanning electron microscope image of the carbon nanotubes obtained after microwave shock treatment for 60 min in Example 2;

[0027] Figure 6 Transmission electron microscopy image of initial carbon nanotubes containing oligowalled carbon nanotubes;

[0028] Figure 7 This is a transmission electron microscope image of the carbon nanotubes obtained after microwave shock treatment for 30 min in Example 1.

[0029] Figure 8 This is a transmission electron microscope image of the carbon nanotubes obtained after microwave shock treatment for 30 min in Example 2.

[0030] Figure 9 This is a transmission electron microscope (TEM) image of the carbon nanotubes obtained after microwave shock treatment for 30 minutes in Example 3. Detailed Implementation

[0031] To make the technical solution and beneficial effects of the present invention more apparent and understandable, a detailed description is provided below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional experimental conditions. Unless otherwise specified, all reagents and raw materials used in this invention are commercially available.

[0032] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, to avoid confusion with this application, some technical features well-known in the art have not been described; that is, not all features of actual embodiments are described herein, nor are well-known functions and steps described in detail.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0034] To fully understand this application, detailed steps and structures will be presented in the following description to illustrate the technical solution of this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0035] Unless otherwise defined, the technical and scientific terms used in this application have the same meanings as those in the technical and scientific field to which this application pertains.

[0036] Unless otherwise specified, the techniques or conditions described in the following embodiments are generally performed in accordance with conventional techniques or conditions described in the literature in this field, or in accordance with the product manual and the manufacturer's recommendations. All numerical ranges in the following embodiments include endpoint values.

[0037] Microwave radiation is a novel technique that triggers chemical reactions and energy conversions by creating a high-energy microenvironment in a confined space. Compared to traditional chemical methods such as etching, microwave radiation does not introduce impurities and can achieve rapid heating. Dipole polarization under microwave shock can alter interfacial properties by modulating surface heteroatom groups.

[0038] Based on this, embodiments of this application provide a method for processing carbon nanotubes. Figure 1 This is a schematic flowchart illustrating a method for processing carbon nanotubes provided in an embodiment of this application. Please refer to... Figure 1 This application provides a method for processing carbon nanotubes, including:

[0039] Step S101: Microwave treatment of the initial carbon nanotubes under an inert atmosphere; the microwave treatment includes: heating the initial carbon nanotubes to a preset temperature using microwaves; and performing microwave shock treatment on the initial carbon nanotubes for a preset time at the preset temperature; wherein the preset temperature is 600℃-1500℃.

[0040] For example, in actual processing, the initial carbon nanotubes can be placed in a microwave reactor, and an inert gas can be introduced to purge the air, ensuring that the microwave treatment is carried out in an inert gas atmosphere. Then, the initial carbon nanotubes are heated to a preset temperature using microwaves, and then subjected to microwave shock treatment at the preset temperature. After the microwave shock treatment is completed, the initial carbon nanotubes are cooled under an inert gas atmosphere, for example, by reducing the temperature of the initial carbon nanotubes to room temperature.

[0041] In this embodiment, an inert gas is continuously introduced during the treatment of the initial carbon nanotubes. Simultaneously, cooling water is connected to the outside of the microwave reactor, and the temperature of the cooling device is set to a predetermined temperature, such as 25°C-30°C, to prevent overheating within the furnace chamber and protect the microwave reactor. Before the microwave shock treatment ends, the introduction of inert gas protects the initial carbon nanotubes during the heating and microwave shock treatment stages. The inert gas flow rate can be, for example, 0.5 L / min-10 L / min. After the microwave shock treatment ends, the introduction of inert gas further protects the initial carbon nanotubes and accelerates the cooling process, shortening the treatment time and improving efficiency. The inert gas flow rate can be, for example, 0.5 L / min-3 L / min.

[0042] It should be noted that the type of inert gas introduced before and after the microwave shock treatment can be the same or different. In some specific embodiments, the type of inert gas introduced before and after the microwave shock treatment can be the same, thus using the same inert gas supply source and simplifying the operation.

[0043] This application embodiment uses a microwave reactor as a non-thermal radiation source. Under the protection of an inert atmosphere, carbon nanotubes are effectively excited through radiation coupling with microwaves. This excites the outer electrons of the initial carbon nanotubes, causing them to collide and release energy, generating heat and light energy, and producing a visible electric arc. Utilizing the electrostatic interaction between carbon nanotubes, the carbon nanotubes gradually disintegrate from their aggregated state, forming more and finer carbon nanotube bundles, thereby effectively increasing the specific surface area of ​​the carbon nanotubes. Furthermore, the inert gas protective atmosphere effectively suppresses large-scale arc discharge during microwave shock treatment, protecting the graphite structure of the carbon nanotubes. In other words, this application embodiment opens the carbon nanotube bundles to effectively increase the specific surface area of ​​the carbon nanotubes while ensuring that the surface structure of the carbon nanotubes is not damaged. In addition, the carbon nanotube processing method provided by this application embodiment is simple to operate, low in cost, and widely applicable.

[0044] In some embodiments, the preset time may be less than or equal to 60 minutes, for example, it may be 1 minute, 5 minutes, 40 minutes or 50 minutes.

[0045] In this embodiment, a preset time for microwave shock treatment of the initial carbon nanotubes that is too short may result in insufficient effect in opening the carbon nanotube bundles, thus failing to effectively increase the specific surface area of ​​the carbon nanotubes. Conversely, a preset time that is too long may cause the opened, fine carbon nanotube bundles to sinter and curl, leading to re-agglomeration and a significant reduction in the specific surface area of ​​the carbon nanotubes, while also easily damaging their surface structure. A preset time of 60 minutes or less can effectively open the carbon nanotube bundles, significantly increasing the specific surface area of ​​the carbon nanotubes, while ensuring that the surface structure of the carbon nanotubes is not damaged.

[0046] In some specific embodiments, the preset time can be 10min-30min, for example, 15min, 20min or 25min.

[0047] In this embodiment, the preset time for microwave shock treatment of the initial carbon nanotubes is 10-30 minutes, which can achieve a relatively ideal effect of opening the initial carbon nanotube bundles, thereby more effectively increasing the specific surface area of ​​carbon nanotubes, while shortening the processing time, saving energy and further improving processing efficiency.

[0048] In this embodiment, when the preset temperature for microwave shock treatment of the initial carbon nanotubes is low, the microwave radiation energy cannot ideally excite the surface electrons of the initial carbon nanotubes, resulting in insufficient effect on opening the carbon nanotube bundles. When the preset temperature for microwave shock treatment of the initial carbon nanotubes is high, the opened fine carbon nanotube bundles are easily sintered and curled, leading to re-agglomeration, which significantly reduces the specific surface area of ​​the carbon nanotubes and easily damages their surface structure. Therefore, in some embodiments, the preset temperature can be 800℃-1000℃, for example, 850℃, 900℃, 950℃, or 980℃.

[0049] In this embodiment of the application, during the process of heating the initial carbon nanotubes to a preset temperature using microwaves, the heating rate can be 5℃ / min-50℃ / min, for example, it can be 10℃ / min, 25℃ / min, 30℃ / min or 40℃ / min, etc.

[0050] In some embodiments, during the process of heating the initial carbon nanotubes to a preset temperature using microwaves, the heating rate can be 200℃ / min-320℃ / min, for example, 220℃ / min, 250℃ / min, 260℃ / min, 280℃ / min or 300℃ / min.

[0051] In this embodiment, microwave heating is used to achieve a high heating rate and rapidly heat the initial carbon nanotubes. This shortens the time the initial carbon nanotubes are exposed to microwave radiation and better protects the surface structure of the carbon nanotubes from damage.

[0052] In some embodiments, the inert atmosphere may be argon or nitrogen.

[0053] Argon or nitrogen are both highly inert gases. In this embodiment, argon or nitrogen is selected as the inert protective atmosphere during the microwave treatment of the initial carbon nanotubes, which can effectively protect the surface structure of the carbon nanotubes from damage. At the same time, argon or nitrogen is readily available and relatively inexpensive.

[0054] In some specific embodiments, the inert atmosphere is argon.

[0055] Since argon is more inert than nitrogen, in this embodiment of the application, argon is selected as the inert protective atmosphere during the microwave treatment of the initial carbon nanotubes. This can provide better protection for the carbon nanotubes and further increase the specific surface area of ​​the treated carbon nanotubes.

[0056] In some embodiments, the initial carbon nanotubes are oligowalled carbon nanotubes, and the specific surface area of ​​the initial carbon nanotubes is less than 840 m².2 / g; The proportion of initial carbon nanotubes with a tube diameter of less than or equal to 10 nm in the initial carbon nanotubes is less than 20%.

[0057] In some embodiments, after subjecting the initial carbon nanotubes to microwave shock treatment for a preset time, the resulting carbon nanotubes have a specific surface area greater than or equal to 930 m². 2 / g; the proportion of carbon nanotubes with a bundle diameter of less than or equal to 10nm in the obtained carbon nanotubes is greater than or equal to 40%.

[0058] Oligowalled carbon nanotubes, especially single-walled carbon nanotubes, are more prone to agglomeration into coarse bundles due to stronger intermolecular forces, resulting in a smaller specific surface area. In the embodiments of this application, the oligowalled carbon nanotubes treated with microwave shock have a larger specific surface area, and the proportion of carbon nanotubes with a bundle diameter of less than or equal to 10 nm is relatively high. In practical applications, carbon nanotubes have a wider range of applications and can perform better.

[0059] In some embodiments, the method for processing carbon nanotubes may further include:

[0060] Determine the target tube bundle diameter distribution range;

[0061] Initial carbon nanotubes were microwave-treated at different preset temperatures, and the first diameter distribution of the microwave-treated carbon nanotubes was measured.

[0062] The target preset temperature is determined based on the proportion of carbon nanotubes with tube diameter within the target tube diameter distribution range in the first tube diameter distribution results.

[0063] In some embodiments, the method for processing carbon nanotubes may further include:

[0064] Initial carbon nanotubes were microwave-treated at a target preset temperature and under different inert atmospheres, and the second diameter distribution of the microwave-treated carbon nanotubes was measured.

[0065] The target inert atmosphere is determined based on the proportion of carbon nanotubes within the target tube diameter distribution range in the second tube diameter distribution results.

[0066] In this embodiment, the microwave shock treatment process can be optimized by observing the changing trend of the carbon nanotube bundle diameter distribution after microwave treatment. For example, based on the changes in the carbon nanotube bundle diameter distribution, the process can be optimized by controlling the temperature or changing the inert gas atmosphere. The carbon nanotube bundle diameter decreases with increasing dissociation and its distribution widens. Therefore, microwave shock treatment conditions that reduce the carbon nanotube bundle diameter and increase the proportion of the bundle diameter within the target bundle diameter distribution range can be selected optimally.

[0067] For example, a suitable target bundle diameter distribution range is determined based on the individual diameters of different initial carbon nanotubes. For instance, when the diameter of a single initial carbon nanotube (more specifically, for example, a single oligowalled carbon nanotube) is less than 4 nm, the target bundle diameter distribution range after bundle dissociation can be determined to be 0 nm-10 nm. When the bundle diameter distribution of the carbon nanotubes after microwave treatment shows an increasing trend between 0 nm and 10 nm, the temperature during microwave shock treatment is increased until the distribution becomes smaller, thereby determining the target preset temperature. Based on this, at the target preset temperature, the inert gas atmosphere is changed, and the change in the bundle diameter of the carbon nanotubes after microwave treatment is monitored, thereby determining the target inert atmosphere. The specific monitoring method can be understood by referring to the method for analyzing the trend of change in the bundle diameter distribution of the carbon nanotubes after microwave treatment in the process of determining the target preset temperature.

[0068] Based on this, this application also provides a carbon nanotube, which is prepared by the steps in the carbon nanotube processing method of any of the foregoing embodiments.

[0069] The technical solution of this application will be further described below with reference to several embodiments and comparative examples.

[0070] It should be noted that the initial carbon nanotubes in the embodiments of this application are commercially available, and may include oligowalled carbon nanotubes and multiwalled carbon nanotubes. In the embodiments of this application, the initial carbon nanotubes containing oligowalled carbon nanotubes are recorded as CNT0, and the initial carbon nanotubes containing multiwalled carbon nanotubes are recorded as CNT0*. The initial carbon nanotubes in Example 4 below are multiwalled carbon nanotubes, while the initial carbon nanotubes in other embodiments and comparative examples are oligowalled carbon nanotubes. The BET specific surface area of ​​CNT0 in the embodiments of this application is 833 m². 2 / g, the BET specific surface area of ​​CNT0* is 297m². 2 / g.

[0071] In this application, the BET specific surface area of ​​carbon nanotubes has a meaning known in the art and can be measured using instruments and methods known in the art. For example, it can be measured using the nitrogen adsorption specific surface area analysis method according to GB / T19587-2017 and calculated using the BET (Brunauer Emmett Teller) method.

[0072] Example 1

[0073] 10g of CNT0 was placed in a crucible and then placed in a microwave reactor. Argon gas was then introduced at a flow rate of 10L / min. The preset temperature was set to 600℃, the heating time to 3min, the microwave input power to 4kW, and the preset microwave shock treatment times to 1min, 10min, 30min, and 60min, respectively, in the programmed temperature control panel. After the microwave shock treatment, the mixture was cooled to room temperature in an argon atmosphere at a flow rate of 3L / min. In this embodiment, the carbon nanotubes obtained after microwave shock treatment for 1min, 10min, 30min, and 60min were labeled CNT1-1, CNT1-10, CNT1-30, and CNT1-60, respectively.

[0074] Example 2

[0075] 10g of CNT0 was placed in a crucible and then placed in a microwave reactor. Argon gas was then introduced at a flow rate of 10L / min. The preset temperature was set to 1000℃, the heating time to 5min, the microwave input power to 4kW, and the preset microwave shock treatment times to 1min, 10min, 30min, and 60min, respectively, in the programmed temperature control panel. After the microwave shock treatment, the mixture was cooled to room temperature in an argon atmosphere at a flow rate of 3L / min. In this embodiment, the carbon nanotubes obtained after microwave shock treatment for 1min, 10min, 30min, and 60min were labeled CNT2-1, CNT2-10, CNT2-30, and CNT2-60, respectively.

[0076] Example 3

[0077] 10g of CNT0 was placed in a crucible and then placed in a microwave reactor. Argon gas was then introduced at a flow rate of 10L / min. The preset temperature was set to 1500℃, the heating time to 8min, the microwave input power to 4kW, and the preset microwave shock treatment times to 1min, 10min, 30min, and 60min, respectively, in the programmed temperature control panel. After the microwave shock treatment, the mixture was cooled to room temperature in an argon atmosphere at a flow rate of 3L / min. In this embodiment, the carbon nanotubes obtained after microwave shock treatment for 1min, 10min, 30min, and 60min were labeled CNT3-1, CNT3-10, CNT3-30, and CNT3-60, respectively.

[0078] Example 4

[0079] 10g of CNT0* was placed in a crucible and then placed in a microwave reactor. Argon gas was then introduced at a flow rate of 10L / min. The preset temperature was set to 1000℃, the heating time to 5min, the microwave input power to 4kW, and the preset microwave shock treatment times to 1min, 10min, 30min, and 60min, respectively, in the programmed temperature control panel. After the microwave shock treatment, the mixture was cooled to room temperature in an argon atmosphere at a flow rate of 3L / min. In this embodiment, the carbon nanotubes obtained after microwave shock treatment for 1min, 10min, 30min, and 60min were labeled CNT4-1, CNT4-10, CNT4-30, and CNT4-60, respectively.

[0080] Example 5

[0081] 10g of CNT0 was placed in a crucible and then placed in a microwave reactor. Nitrogen gas was then introduced at a flow rate of 10L / min. The preset temperature was set to 1000℃, the heating time to 5min, the microwave input power to 4kW, and the preset microwave shock treatment times to 1min, 10min, 30min, and 60min, respectively, in the programmed temperature control panel. After the microwave shock treatment, the mixture was cooled to room temperature in a nitrogen atmosphere at a flow rate of 3L / min. In this embodiment, the carbon nanotubes obtained after microwave shock treatment for 1min, 10min, 30min, and 60min were labeled CNT5-1, CNT5-10, CNT5-30, and CNT5-60, respectively.

[0082] Example 6

[0083] 10g of CNT0 was placed in a crucible and then placed in a microwave reactor. Argon gas was then introduced at a flow rate of 10L / min. The preset temperature was set to 800℃, the heating time to 4min, the microwave input power to 4kW, and the preset microwave shock treatment times to 1min, 10min, 30min, and 60min, respectively, in the programmed temperature control panel. After the microwave shock treatment, the mixture was cooled to room temperature in an argon atmosphere at a flow rate of 3L / min. In this embodiment, the carbon nanotubes obtained after microwave shock treatment for 1min, 10min, 30min, and 60min were labeled CNT6-1, CNT6-10, CNT6-30, and CNT6-60, respectively.

[0084] Example 7

[0085] 10g of CNT0 was placed in a crucible and then placed in a microwave reactor. Argon gas was then introduced at a flow rate of 10L / min. The preset temperature was set to 800℃, the heating time to 2.5min, the microwave input power to 4kW, and the preset microwave shock treatment times to 1min, 10min, 30min, and 60min, respectively, in the programmed temperature control panel. After the microwave shock treatment, the mixture was cooled to room temperature in an argon atmosphere at a flow rate of 3L / min. In this embodiment, the carbon nanotubes obtained after microwave shock treatment for 1min, 10min, 30min, and 60min were labeled CNT7-1, CNT7-10, CNT7-30, and CNT7-60, respectively.

[0086] Example 8

[0087] 10g of CNT0 was placed in a container made of high-temperature resistant and breathable porous silicate material and placed in a microwave reactor. Argon gas was then introduced at a flow rate of 10L / min. The preset temperature was set to 1000℃, the heating time to 30min, the microwave input power to 4kW, and the preset microwave shock treatment times to 1min, 10min, 30min, and 60min, respectively, in the programmed temperature control panel. After the microwave shock treatment, the mixture was cooled to room temperature in an argon atmosphere at a flow rate of 3L / min. In this embodiment, the carbon nanotubes obtained after microwave shock treatment for 1min, 10min, 30min, and 60min were labeled CNT8-1, CNT8-10, CNT8-30, and CNT8-60, respectively.

[0088] Comparative Example 1

[0089] 10g of CNT0 was placed in a crucible and then placed in a microwave reactor. Argon gas was then introduced at a flow rate of 10L / min. The preset temperature was set to 500℃, the heating time to 2.5min, the microwave input power to 4kW, and the preset microwave shock treatment times to 1min, 10min, 30min, and 60min, respectively, in the programmed temperature control panel. After the microwave shock treatment, the mixture was cooled to room temperature in an argon atmosphere at a flow rate of 3L / min. In this embodiment, the carbon nanotubes obtained after microwave shock treatment for 1min, 10min, 30min, and 60min were labeled CNT9-1, CNT9-10, CNT9-30, and CNT9-60, respectively.

[0090] Comparative Example 2

[0091] 10g of CNT0 was placed in a crucible and then placed in a microwave reactor. Argon gas was then introduced at a flow rate of 10L / min. The preset temperature was set to 1600℃, the heating time to 10min, the microwave input power to 4kW, and the preset microwave shock treatment times to 1min, 10min, 30min, and 60min, respectively, in the programmed temperature control panel. After the microwave shock treatment, the mixture was cooled to room temperature in an argon atmosphere at a flow rate of 3L / min. In this embodiment, the carbon nanotubes obtained after microwave shock treatment for 1min, 10min, 30min, and 60min were labeled CNT10-1, CNT10-10, CNT10-30, and CNT10-60, respectively.

[0092] Comparative Example 3

[0093] 10g of CNT0 was placed in a quartz boat and then placed in a high-temperature heater. Compressed air was then introduced at a flow rate of 0.5L / min. The temperature was then set to 450℃, the heating time to 30min, and the holding and oxidation treatment times to 1min, 10min, 30min, and 60min, respectively, in the programmed temperature control panel. After the oxidation treatment, the carbon nanotubes were cooled to room temperature in a compressed air atmosphere at a flow rate of 3L / min. In this embodiment, the carbon nanotubes obtained after holding the treatment for 1min, 10min, 30min, and 60min were labeled as CNT11-1, CNT11-10, CNT11-30, and CNT11-60, respectively.

[0094] To verify the performance of the carbon nanotubes prepared in the above embodiments and comparative examples, performance tests were conducted on the carbon nanotubes obtained in the above embodiments and comparative examples. Specific results are as follows:

[0095] (I) Scanning electron microscopy morphology

[0096] Figure 2 This is a scanning electron microscope (SEM) image of the initial carbon nanotubes containing oligowalled carbon nanotubes, i.e., a scanning electron microscope (SEM) image of CNT0. Figure 3 The image shown is a scanning electron microscope (SEM) image of carbon nanotubes obtained after microwave shock treatment for 1 minute in Example 2, namely, the SEM image of CNT2-1. Figure 4 The image shown is a scanning electron microscope (SEM) image of carbon nanotubes obtained after microwave shock treatment for 30 min in Example 2, namely, the SEM image of CNT2-30. Figure 5 The image shown is a scanning electron microscope (SEM) image of carbon nanotubes obtained after microwave shock treatment for 60 min in Example 2, namely, the SEM image of CNT2-60.

[0097] Depend on Figures 3 to 5 and Figure 2The comparison shows that after microwave shock treatment for different durations, carbon nanotubes (CNTO) gradually dissociate from an aggregated state, generating fine and dense tube bundles, thus effectively increasing the specific surface area of ​​carbon nanotubes.

[0098] Depend on Figures 3 to 5 It can be seen that as the microwave shock treatment time increases, the dissociation effect of carbon nanotubes first gradually increases and then remains basically unchanged, even showing a downward trend. Combined with... Figure 4 It can be seen that the carbon nanotube bundles obtained after microwave shock treatment for 30 minutes are fully opened, forming relatively fine and uniform dense carbon nanotube bundles, thus significantly increasing the specific surface area of ​​the carbon nanotubes. Combined with... Figure 5 It can be seen that the diameter of the carbon nanotube bundles obtained after microwave shock treatment for 60 minutes is comparable to that obtained after microwave shock treatment for 30 minutes, and some carbon nanotube bundles even show a tendency to re-aggregate.

[0099] Therefore, in this embodiment, a longer preset time for microwave shock treatment of carbon nanotubes is not necessarily better. A longer treatment time may lead to the sintering and curling of the opened fine carbon nanotube bundles, causing them to agglomerate again, resulting in a significant reduction in the specific surface area of ​​the carbon nanotubes and easily damaging their surface structure. Based on the above embodiments, controlling the preset time for microwave shock treatment of carbon nanotubes to be less than or equal to 60 minutes can achieve a better effect in opening the carbon nanotube bundles.

[0100] (II) Transmission electron microscopy morphology

[0101] Figure 6 This is a transmission electron microscope (TEM) image of the initial carbon nanotubes containing oligowalled carbon nanotubes, i.e., a TEM image of CNT0. Figure 7 The image shows a transmission electron microscope (TEM) image of carbon nanotubes obtained after microwave shock treatment for 30 min in Example 1, namely, the TEM image of CNT1-30. Figure 8 The image shown is a transmission electron microscope (TEM) image of carbon nanotubes obtained after microwave shock treatment for 30 min in Example 2, namely, the TEM image of CNT2-30. Figure 9 The image shown is a transmission electron microscope (TEM) image of carbon nanotubes obtained after microwave shock treatment for 30 min in Example 3, specifically the TEM image of CNT3-30.

[0102] Depend on Figures 7 to 9 and Figure 6 The comparison shows that after microwave shock treatment of carbon nanotubes (CNTO) in different embodiments, the carbon nanotubes gradually disintegrate from an aggregated state, generating fine and dense bundle branches, thus effectively increasing the specific surface area of ​​the carbon nanotubes. This is consistent with the results of scanning electron microscopy morphology.

[0103] The preset temperatures for microwave shock treatment of carbon nanotubes in Examples 1 to 3 were 600℃, 1000℃, and 1500℃, respectively. Figures 7 to 9 It can be seen that, under the same microwave shock treatment time, the preset temperature of the microwave shock treatment also affects the dissociation effect of carbon nanotubes. As the microwave shock treatment temperature increases, the dissociation effect of carbon nanotubes first gradually increases and then remains basically unchanged, even showing a downward trend. Combined with... Figure 8 It can be seen that the carbon nanotubes obtained by microwave shock treatment at 1000℃ have fully opened up, forming relatively fine and uniform dense carbon nanotube bundles, thus significantly increasing the specific surface area of ​​the carbon nanotubes. Combined with... Figure 9 It can be seen that the diameter of carbon nanotube bundles obtained by microwave shock treatment at 1500℃ is comparable to that of carbon nanotube bundles obtained by microwave shock treatment at 1000℃, and some carbon nanotube bundles even show a tendency to re-aggregate.

[0104] Therefore, in this embodiment, the preset temperature for microwave shock treatment of carbon nanotubes is not necessarily higher. Higher temperatures increase the likelihood of the opened, fine carbon nanotube bundles sintering and curling, leading to re-agglomeration, a significant reduction in the specific surface area of ​​the carbon nanotubes, and damage to their surface structure. Based on the above embodiments, controlling the preset temperature for microwave shock treatment of carbon nanotubes within the range of 600℃-1500℃ effectively opens the carbon nanotube bundles while ensuring the surface structure remains intact.

[0105] (III) Physical Performance Testing

[0106] The BET specific surface area of ​​the carbon nanotubes obtained in Examples 1 to 8 and Comparative Examples 1 to 3 was tested. The microwave processing parameters and BET test results for different examples and comparative examples are shown in Table 1.

[0107] As shown in Table 1, in Examples 1 to 3, Examples 5 to 8, and Comparative Examples 1 to 3, the initial carbon nanotubes treated by microwave were all CNT0. A comparison of the specific surface area values ​​of the carbon nanotubes obtained from Examples 1 to 3 and Examples 5 to 8 with those of CNT0 shows that, within a temperature range of 600℃ to 1500℃, microwave shock treatment of CNT0 for different preset times significantly increased the specific surface area of ​​the resulting carbon nanotubes compared to that of CNT0.

[0108] Table 1

[0109]

[0110]

[0111] Based on the data in Table 1, a comparison of the specific surface area values ​​of carbon nanotubes obtained from Comparative Examples 1 and 2 with those of CNT0 shows that, under both low and high preset temperatures, microwave shock treatment of carbon nanotubes did not significantly improve their specific surface area. In particular, at high temperatures, the specific surface area of ​​the carbon nanotubes actually decreased. This is consistent with the results obtained from transmission electron microscopy (TEM), because higher treatment temperatures make it easier for the opened, fine carbon nanotube bundles to sinter and curl, leading to re-agglomeration and a significant reduction in the specific surface area. Furthermore, it easily damages the surface structure of the carbon nanotubes. Therefore, controlling the preset temperature for microwave shock treatment of carbon nanotubes within the range of 600℃-1500℃ can effectively open the carbon nanotube bundles while ensuring that the surface structure of the carbon nanotubes is not damaged.

[0112] In addition, Comparative Example 3 uses the oxidation etching method in related technologies to process CNT0. As can be seen from Table 1, the specific surface area of ​​carbon nanotubes obtained by the oxidation etching method is not significantly improved. Moreover, when the processing time is extended to 60 min, the surface structure of carbon nanotubes is destroyed due to excessive oxidation reaction, resulting in a significant decrease in the specific surface area of ​​carbon nanotubes. The dissociation effect of this method on carbon nanotube bundles is far lower than that of microwave treatment on carbon nanotube bundles.

[0113] As shown in Table 1, Examples 1 to 8 included experiments involving microwave shock treatment of initial carbon nanotubes for 1 min, 10 min, 30 min, and 60 min, respectively. The results show a similar pattern in each example: with increasing microwave shock treatment time, the dissociation effect of carbon nanotubes initially gradually increased and then remained essentially unchanged, even showing a downward trend. Combining the data in Table 1, it can be seen that in different examples, the carbon nanotubes obtained after 30 min of microwave shock treatment showed the largest increase in specific surface area, indicating that the carbon nanotube bundles were more fully opened, which is consistent with the results of scanning electron microscopy morphology. Based on the test results of the above examples, it can be seen that controlling the preset time for microwave shock treatment of carbon nanotubes to be less than or equal to 60 min can effectively improve the specific surface area of ​​carbon nanotubes. Furthermore, controlling the preset time for microwave shock treatment of carbon nanotubes to be between 10 min and 30 min can further improve the specific surface area of ​​carbon nanotubes and shorten the treatment time, thereby improving treatment efficiency.

[0114] As shown in Table 1, the inert atmosphere for microwave treatment of carbon nanotubes in Example 2 was argon, while in Example 5, except for the use of nitrogen as the inert atmosphere, the other treatment conditions were the same as in Example 2. Comparing the specific surface areas of the carbon nanotubes treated in Examples 2 and 5, it can be seen that microwave treatment under an argon atmosphere has a better effect on improving the specific surface area of ​​carbon nanotubes than microwave treatment under a nitrogen atmosphere. Because argon is more inert than nitrogen, in this application, argon is selected as the inert protective atmosphere during the microwave treatment of the initial carbon nanotubes to provide better protection and further improve the specific surface area of ​​the treated carbon nanotubes.

[0115] Furthermore, as shown in Table 1, the initial carbon nanotubes treated with microwave in Example 4 were CNT0*. A comparison of the specific surface area values ​​of the carbon nanotubes obtained in Example 4 with those of CNT0* shows that microwave shock treatment of multi-walled carbon nanotubes at a preset temperature for a preset time can effectively increase the specific surface area of ​​multi-walled carbon nanotubes, exhibiting a similar effect to that of oligo-walled carbon nanotubes. Therefore, the microwave treatment method in this application is applicable not only to increasing the specific surface area of ​​oligo-walled carbon nanotubes but also to increasing the specific surface area of ​​multi-walled carbon nanotubes, demonstrating broad applicability.

[0116] The bundle distribution of carbon nanotubes obtained in Examples 1 to 3, 5 and 6 above was statistically analyzed, and the specific results are shown in Table 2.

[0117] The method for statistical analysis of the bundle distribution of treated carbon nanotubes was to select carbon nanotubes obtained by microwave shock treatment for 30 min in different examples as representatives, perform transmission electron microscopy (TEM) analysis, and perform TEM analysis on the initial carbon nanotubes CNT0 for comparison. In Table 2, CNT1-30, CNT2-30, CNT3-30, CNT5-30, and CNT6-30 correspond to the numbers of the carbon nanotubes obtained by microwave shock treatment for 30 min in Examples 1, 2, 3, 5, and 6, respectively.

[0118] Table 2

[0119]

[0120] After microwave shock treatment at different temperatures, the diameters of carbon nanotubes with varying degrees of bundle dissociation were measured and statistically analyzed. Transmission electron microscopy (TEM) images clearly showed the bundle state of the carbon nanotubes after microwave shock treatment under different conditions. In the TEM images of CNT1-30, CNT2-30, CNT3-30, CNT5-30, and CNT6-30, the bundle diameters of a random number of carbon nanotubes were statistically analyzed (e.g., 200 randomly selected nanotubes). This allowed us to obtain the proportion of carbon nanotubes with bundle diameters distributed within different ranges in CNT1-30, CNT2-30, CNT3-30, CNT5-30, and CNT6-30.

[0121] As shown in Table 2, in the initial carbon nanotube CNT0, the proportion of carbon nanotubes with a bundle diameter d greater than 0 nm and less than or equal to 10 nm was relatively small, while the proportion of carbon nanotubes with a bundle diameter d greater than 10 nm and less than or equal to 20 nm was the largest. In CNT1-30, CNT2-30, CNT3-30, CNT5-30, and CNT6-30 obtained after microwave treatment, the proportion of carbon nanotubes with a bundle diameter d greater than 0 nm and less than or equal to 10 nm was the largest, and more than twice the proportion of carbon nanotubes with a bundle diameter greater than 0 nm and less than or equal to 10 nm in CNT0. Therefore, it can be concluded that the carbon nanotube bundles in Examples 1, 2, 3, 5, and 6 were well opened after microwave treatment, forming relatively fine carbon nanotube bundles. This is consistent with the test results in Table 1.

[0122] Furthermore, referring to Tables 1 and 2, the preset temperatures in Examples 1, 6, 2, and 3 were 600℃, 800℃, 1000℃, and 1500℃, respectively. The results in Table 1 show that the specific surface area of ​​the carbon nanotubes after microwave treatment increases with increasing preset temperature. The specific surface area of ​​the carbon nanotubes obtained in Example 3 is basically the same as that obtained in Example 2, meaning that the increase in specific surface area of ​​the carbon nanotubes after microwave shock treatment is minimal when the preset temperature increases from 1000℃ to 1500℃. The results of the carbon nanotube bundle distribution in Table 2 show that, with the increase of microwave treatment temperature, the proportion of bundle diameters greater than 0 nm and less than or equal to 10 nm in CNT1-30, CNT6-30, CNT2-30, and CNT3-30 first increases and then decreases. At 600℃-1000℃, the degree of dissociation of carbon nanotubes gradually increases with the increase of temperature, reaching the maximum at the preset temperature of 1000℃. The carbon nanotube bundles obtained by microwave shock treatment are opened relatively fully. The proportion of carbon nanotubes with bundle diameters greater than 0 nm and less than or equal to 10 nm is the highest in CNT2-30.

[0123] Furthermore, as shown in Table 2, when the preset temperature increases from 1000℃ to 1500℃, the proportion of carbon nanotubes with a bundle diameter greater than 0 nm and less than or equal to 10 nm in CNT3-30 decreases significantly compared to CNT2-30. At a preset temperature of 800℃, the proportion of carbon nanotubes with a bundle diameter greater than 0 nm and less than or equal to 10 nm in CNT6-30 is comparable to that in CNT3-30.

[0124] In Example 5 for CNT5-30, compared to Example 2 for CNT2-30, the inert atmosphere for microwave shock treatment was changed from argon to nitrogen, while other conditions remained the same. Combined with the results in Table 2, the proportion of tubes with diameters greater than 0 nm and less than or equal to 10 nm in CNT5-30 was lower than that in CNT2-30. This result indicates that a more inert argon atmosphere is more conducive to the dissociation of carbon nanotube bundles.

[0125] Therefore, within the temperature range of 600℃-1500℃, the microwave shock treatment of carbon nanotubes at 800℃-1000℃ in an argon atmosphere is the most effective and can effectively open up the bundles of oligowalled carbon nanotubes.

[0126] In this embodiment, initial carbon nanotubes are placed in a microwave reactor and subjected to microwave shock treatment at a preset temperature for a preset time. This breaks up the aggregated bundles of initial carbon nanotubes, forming more finer bundles, thereby significantly increasing the specific surface area of ​​the treated carbon nanotubes. Furthermore, transmission electron microscopy (TEM) analysis shows that the surface structure of the treated carbon nanotubes remains intact. The carbon nanotube processing method provided in this embodiment is simple to operate, low in cost, and widely applicable. It can be applied to the post-processing of large-scale carbon nanotube production, further improving the performance of carbon nanotubes and greatly expanding their applications in various fields.

[0127] It should be noted that the carbon nanotube processing method embodiments provided in this application and the carbon nanotube embodiments belong to the same concept; the technical features in the technical solutions described in each embodiment can be arbitrarily combined without conflict.

[0128] It should be understood that the above embodiments are exemplary and are not intended to encompass all possible implementations included in the claims. Various modifications and changes can be made to the above embodiments without departing from the scope of this disclosure. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form other embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments only illustrate several implementations of the present invention and do not limit the scope of protection of this patent.

Claims

1. A method for processing carbon nanotubes, characterized in that, The method includes: Initial carbon nanotubes are subjected to microwave treatment under an inert atmosphere, wherein the inert atmosphere is argon, and the initial carbon nanotubes are oligowalled carbon nanotubes or multiwalled carbon nanotubes; the microwave treatment includes: The initial carbon nanotubes were heated to a preset temperature using microwaves. At the preset temperature, the initial carbon nanotubes are subjected to microwave shock treatment for a preset time, which excites the outer electrons of the initial carbon nanotubes. The electrostatic interaction between the initial carbon nanotubes is used to gradually dissociate the initial carbon nanotubes from their aggregated state. The preset temperature is 600℃-1500℃, and the preset time is 10min-30min.

2. The method for processing carbon nanotubes according to claim 1, characterized in that, The preset temperature is 800℃-1000℃.

3. The method for processing carbon nanotubes according to claim 1, characterized in that, During the process of heating the initial carbon nanotubes to a preset temperature using microwaves, the heating rate is 200℃ / min-320℃ / min.

4. The method for processing carbon nanotubes according to any one of claims 1 to 3, characterized in that, The specific surface area of ​​the initial carbon nanotubes is less than 840 m². 2 / g; the proportion of initial carbon nanotubes with a tube diameter less than or equal to 10nm in the initial carbon nanotubes is less than 20%.

5. The method for processing carbon nanotubes according to claim 4, characterized in that, After subjecting the initial carbon nanotubes to microwave shock treatment for a preset time, the resulting carbon nanotubes have a specific surface area greater than or equal to 930 m². 2 / g; the proportion of carbon nanotubes with a tube diameter of less than or equal to 10nm in the obtained carbon nanotubes is greater than or equal to 40%.

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