Method for controlling diameter of single-walled carbon nanotubes using acetonitrile

Abstract

The application discloses a method for controlling the diameter of single-wall carbon nanotubes by acetonitrile, and belongs to the technical field of material industrial production. The method is prepared by high-temperature calcination under the protection of inert gas, with toluene as a carbon source, thiophene as a catalyst, iron chloride as a catalyst carrier, water as a solvent, and acetonitrile as a control agent. The method comprises the following steps: adding iron chloride, thiophene, water and an acetonitrile solution into toluene, and stirring to obtain a mixed solution; injecting the mixed solution into a high-temperature reaction furnace for reaction by taking nitrogen as a carrier, so as to obtain a crude product; and performing purification treatment on the crude product, so as to obtain pure single-wall carbon nanotubes. By adjusting the amount of acetonitrile, the growth process of the carbon nanotubes can be effectively controlled, and the diameter of the single-wall carbon nanotubes can be controlled.

Description

Technical Field

[0001] This invention belongs to the field of materials industrial production technology, and in particular relates to a method for controlling the diameter of single-walled carbon nanotubes with acetonitrile. Background Technology

[0002] Single-walled carbon nanotubes (SWNTs) are nanoscale tubular materials composed of carbon atoms, resembling hollow nanotubes. SWNTs have wide applications in various fields. In the energy sector, they are used as electrode materials in batteries and supercapacitors, improving energy density and storage performance. Furthermore, SWNTs can be used in solar cells, converting solar energy into electricity as light-absorbing materials. In sensing technology, SWNTs possess high sensitivity and selectivity, making them suitable for manufacturing chemical and biosensors. These sensors can detect pollutants, biomolecules, gases, and ions in the environment, contributing to environmental monitoring and protection, food safety, and public health. In aerospace, SWNTs can be used to manufacture lightweight and high-strength composite materials, reducing the weight of aircraft and spacecraft and improving their performance and fuel efficiency. In electronics, SWNTs are considered the next-generation electronic material after silicon, and can be used to create smaller, faster, and more efficient electronic devices, such as transistors, transparent conductive films, and flexible electronic devices. In nanomedicine, SWNTs are being researched for cancer treatment and diagnosis. By encapsulating drugs on single-walled carbon nanotubes (SUVs), precise drug delivery and targeted therapy can be achieved, minimizing damage to healthy tissues. In materials reinforcement and lubrication, SUVs can enhance the mechanical properties of composite materials, improving their toughness and strength. They can also act as lubricants, reducing friction and wear and extending the lifespan of mechanical equipment. In environmental remediation, SUVs can be used to purify organic and inorganic pollutants in water and air. Their high adsorption capacity and catalytic activity make them an effective tool for addressing pollution problems. In summary, as a unique nanomaterial, SUVs have enormous application potential in multiple fields, including composite materials, energy, electronics, sensing technology, medicine, environmental remediation, and aerospace.

[0003] There are various methods for preparing single-walled carbon nanotubes (SHU), including chemical vapor deposition (CVD), arc discharge, and floating catalysis. Among these, floating catalysis is a relatively novel and promising method. This method involves introducing a carbon source and catalyst together into the reaction zone at high temperature, and then using an airflow to bring the carbon source into contact with the catalyst, thereby allowing SHU to grow on the catalyst surface. Compared to other methods, floating catalysis offers better controllability and scalability, and can be performed at lower temperatures. This method can achieve high-yield production of SHU and is expected to promote the application of carbon nanotubes in various fields. Furthermore, floating catalysis technology guides the carbon source and catalyst to the reaction zone via an airflow, enabling the carbon source to react with the catalyst and achieve SHU growth. This method offers better controllability and scalability, and is expected to make progress in the large-scale preparation of SHU.

[0004] However, although there have been studies on the preparation of single-walled carbon nanotubes by floating catalysis, it has not yet reached a mature stage, and the produced products are not uniform in diameter, with the diameter width not within a stable range, which presents a technical bottleneck. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a method for controlling the diameter of single-walled carbon nanotubes using acetonitrile.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for controlling the diameter of single-walled carbon nanotubes using acetonitrile is disclosed, which uses toluene as the carbon source, thiophene as the catalyst, ferric chloride as the catalyst support, water as the solvent, and acetonitrile as the control agent, and is prepared by high-temperature calcination under inert gas protection.

[0008] Specifically, a method for controlling the diameter of single-walled carbon nanotubes using acetonitrile includes the following steps: adding ferric chloride, thiophene, water, and acetonitrile solution to toluene and stirring to obtain a mixed solution; using nitrogen as a carrier, injecting the mixed solution into a high-temperature reactor to react and obtain a crude product; and purifying the crude product to obtain pure single-walled carbon nanotubes.

[0009] Furthermore, the ratio of the toluene, ferric chloride, thiophene, water, and acetonitrile solution is 500 mL: 10 g: (5-30) mL: 60 mL: (15-35) mL.

[0010] Furthermore, the volume ratio of the acetonitrile solution to toluene is (15-35):500.

[0011] Further, the volume ratio of thiophene to toluene is (50-30):500. When thiophene is added in excess, the diameter of the carbon nanotubes increases: excessive thiophene may promote the growth rate of carbon nanotubes, leading to an increase in diameter. Excessive thiophene can prolong the growth time of carbon nanotubes, resulting in a wider range of tube length distribution. Moreover, excessive thiophene may lead to excessive impurities inside the carbon nanotubes, affecting their structural integrity. When thiophene is added in insufficient amounts, the yield of carbon nanotubes decreases, as thiophene is an important carbon source for carbon nanotube synthesis. Furthermore, the lack of heterogeneous thiophene may lead to uneven growth of carbon nanotubes, preventing the formation of uniformly distributed tubular structures. Finally, insufficient thiophene may cause structural variations in the carbon nanotubes, resulting in irregular tube wall structures.

[0012] Furthermore, the ratio of the amount of ferric chloride to the amount of toluene is 1:50 (g / mL).

[0013] Furthermore, the reaction temperature is 1100℃, and the heating rate is 5℃ / min.

[0014] Furthermore, the injection rate of the mixed solution into the high-temperature reactor is 200-500 μL / min.

[0015] Furthermore, the purification process includes air oxidation and acid treatment. The specific steps are as follows: the crude product is calcined in air at 600°C for 2-3 hours, the calcined product is heated and stirred in a 6M acid solution, filtered, dried, and the dried product is further heated and stirred in a 6M acid solution.

[0016] Furthermore, the heating and stirring refers to stirring at 100°C for 24 hours.

[0017] Furthermore, the acid solution is one or more of concentrated nitric acid, concentrated hydrochloric acid, and aqua regia.

[0018] Furthermore, the diameter of the carbon nanotubes ranges from 0.88 to 1.87 nm.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects:

[0020] This invention achieves stable growth of single-walled carbon nanotube diameters by precisely controlling the amount of acetonitrile added to the system. In this method, by adjusting the yield of acetonitrile, the growth process of carbon nanotubes can be effectively controlled, thereby controlling the diameter of the single-walled carbon nanotubes. Attached Figure Description

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

[0022] Figure 1 Raman and scanning electron microscopy results of the single-walled carbon nanotubes prepared in Example 1;

[0023] Figure 2 Raman and scanning electron microscopy results of the single-walled carbon nanotubes prepared in Example 2;

[0024] Figure 3 Raman and scanning electron microscopy results of the single-walled carbon nanotubes prepared in Example 3;

[0025] Figure 4 Raman and scanning electron microscopy results of the single-walled carbon nanotubes prepared in Example 4;

[0026] Figure 5 Raman and scanning electron microscopy results for the single-walled carbon nanotubes prepared for Comparative Example 1. Detailed Implementation

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0028] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0029] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0030] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0031] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0032] Iron, as a catalyst support, can effectively catalyze the rearrangement of carbon source molecules and the formation of single-walled carbon nanotubes in floating catalysis. Ferric chloride is widely used and relatively inexpensive, making it a viable catalyst choice for industrial production. Iron in ferric chloride is relatively easy to remove during post-treatment purification. Separation techniques such as acid washing and oxidation can effectively remove catalyst residues and impurities, thereby obtaining a relatively pure single-walled carbon nanotube product.

[0033] Acetonitrile acts as both a solvent and a carbon source in the synthesis of single-walled carbon nanotubes (SUVs). As a solvent, acetonitrile provides a suitable reaction environment and promotes the growth of carbon nanotubes. The diameter of SUVs can be controlled by adding a specific concentration of acetonitrile to toluene. Precise control of the acetonitrile concentration in the system can result in more uniform SUV diameters. The addition of acetonitrile can alter the growth pattern of SUVs on the catalyst surface. Furthermore, the presence of acetonitrile can lead to the interconnection of carbon nanotubes, forming bundles or clusters, reducing the purity and structural consistency of the SUVs. Therefore, the amount of acetonitrile added needs to be controlled during the synthesis of SUVs to ensure an appropriate growth rate and a good tubular structure. Optimizing reaction conditions and the amount of acetonitrile can improve the quality and yield of SUVs. Because nitrogen atoms in acetonitrile molecules have a high affinity for catalyst elements such as iron (Fe), this may limit the binding of some reaction sites on the catalyst surface to carbon atoms. Due to the presence of acetonitrile, carbon atoms tend to grow in a vertical manner, resulting in a smaller diameter of the SUVs. Therefore, the amount of acetonitrile added should be moderate. Excessive acetonitrile may lead to adverse effects, such as catalyst deactivation or uneven tube diameter distribution. In the process of synthesizing single-walled carbon nanotubes, continuously increasing the concentration of acetonitrile can reduce the average diameter of the prepared samples to below 1 nm, but the defects in the tubes also increase significantly.

[0034] Single-walled carbon nanotubes of different diameters have different functions and applications. Small-diameter (<1nm) single-walled carbon nanotubes have potential applications in flexible electronic devices and catalytic reactions; medium-diameter (1-2nm) single-walled carbon nanotubes have potential in energy storage and sensors; large-diameter (>2nm) single-walled carbon nanotubes can be used for drug delivery and biomedical applications. The appropriate diameter range should be selected based on specific needs.

[0035] This invention provides a method for controlling the diameter of single-walled carbon nanotubes using acetonitrile, comprising the following steps:

[0036] (1) Add ferric chloride, thiophene, water and acetonitrile solution to toluene and stir for 1-2 hours to obtain a mixed solution;

[0037] (2) Using nitrogen as a carrier, the mixed solution is injected into a high-temperature reactor to react and obtain a crude product; choosing nitrogen to carry the mixed solution into the high-temperature vertical reactor helps to mass produce single-walled carbon nanotubes on the surface of ferric chloride, and the volume of toluene is vaporized at a high temperature of 1100°C, which is beneficial to the growth of single-walled carbon nanotubes.

[0038] (3) The crude product is purified to obtain pure single-walled carbon nanotubes.

[0039] In some preferred embodiments of the present invention, the volume ratio of the toluene, ferric chloride, thiophene, water, and acetonitrile solution is 500 mL: 10 g: (5-30) mL: 60 mL: (15-35) mL. The amount of thiophene is preferably 10 mL, and the volume of the acetonitrile solution is preferably 15-25 mL, more preferably 15 mL, 17.5 mL, or 25 mL. That is, the volume ratio of the toluene, ferric chloride, thiophene, water, and acetonitrile solution is preferably 500 mL: 10 g: 10 mL: 60 mL: 15 mL, 500 mL: 10 g: 10 mL: 60 mL: 25 mL, or 500 mL: 10 g: 10 mL: 60 mL: 35 mL.

[0040] In some preferred embodiments of the present invention, the reaction temperature is 1100°C and the heating rate is 5°C / min.

[0041] In some preferred embodiments of the present invention, the injection rate of the mixed solution into the high-temperature reactor is 200-500 μL / min, preferably 500 μL / min.

[0042] In some preferred embodiments of the present invention, the purification process includes air oxidation and acid treatment. The specific steps are as follows: the crude product is calcined in air at 600°C for 2-3 hours to remove amorphous carbon from the surface; then the calcined product is placed in a 6M acid solution and stirred at 100°C for 24 hours; filtered; dried; and the dried product is further placed in a 6M acid solution and stirred at 100°C for 24 hours to remove excess metal impurities from the crude product.

[0043] In some preferred embodiments of the present invention, the acid solution is one or more of concentrated nitric acid, concentrated hydrochloric acid, and aqua regia.

[0044] This invention successfully achieved stable control of the diameter of single-walled carbon nanotubes (SUVs) by adjusting the amount of acetonitrile added. SUVs of different diameters possess different functions and application characteristics. The innovation of this invention lies in providing more possibilities for the application of SUVs by adjusting the acetonitrile content. The SUVs prepared by the above method exhibit uniform and stable diameter distribution after control, and their high G / D value has been demonstrated by Raman spectroscopy and other methods.

[0045] All raw materials used in the following embodiments of the present invention are commercially available. The acetonitrile solution used in the following embodiments of the present invention has a concentration of 99.9% and was manufactured by Qilu Petrochemical.

[0046] The following embodiments are further illustrations of the technical solution of the present invention.

[0047] Example 1

[0048] A method for controlling the diameter of single-walled carbon nanotubes using acetonitrile includes the following steps:

[0049] (1) Add 10g of ferric chloride, 10mL of thiophene, 60mL of water and 0mL of acetonitrile solution to 500mL of toluene, stir for 2h to obtain a mixed solution;

[0050] (2) Using nitrogen as a carrier, the mixed solution is injected into a high-temperature reactor at an injection rate of 500 μL / min for reaction. The reaction temperature is 1100℃ and the heating rate is 5℃ / min to obtain the crude product.

[0051] (3) The crude product was calcined in air at 600°C for 3 hours. Then the calcined product was placed in concentrated nitric acid with a concentration of 6M and stirred at 100°C for 24 hours. After filtration and drying, the dried product was placed in concentrated hydrochloric acid with a concentration of 6M and stirred at 100°C for 24 hours to obtain pure single-walled carbon nanotubes (purity of 70% and diameter of 1.87 nm).

[0052] Example 2

[0053] Same as Example 1, except that 15 mL of acetonitrile solution is added in step (1).

[0054] The obtained single-walled carbon nanotubes had a purity of 86% and a diameter of 1.52 nm.

[0055] Example 3

[0056] Same as Example 1, except that 17.5 mL of acetonitrile solution was added in step (1). The obtained single-walled carbon nanotubes had a purity of 93% and a diameter of 1.2 nm.

[0057] Example 4

[0058] Same as Example 1, except that 25 mL of acetonitrile solution was added in step (1). The obtained single-walled carbon nanotubes had a purity of 80% and a diameter of 0.88 nm.

[0059] Comparative Example 1

[0060] Same as Example 1, except that 40 mL of acetonitrile solution was added in step (1). The obtained single-walled carbon nanotubes had a purity of 74% and a diameter of 0.86 nm.

[0061] Raman spectroscopy (wavelength 234 nm) and electron microscopy were performed on the single-walled carbon nanotubes prepared in Examples 1-5 of this invention. The results are as follows: Figure 1-5 As can be seen from the figure, the single-walled carbon nanotubes prepared in Examples 1-4 have high G / D values ​​(the ratio of the peak value of the G-line to the peak value of the D-line) of 71, 131.17, 219.84, and 104.95, respectively, while the G / D value of Comparative Example 1 is only 52.4. This indicates that the single-walled carbon nanotubes prepared by the methods in Examples 1-4 have a higher degree of graphitization and fewer defects. The single-walled carbon nanotubes prepared in Comparative Example 1 did not yield the desired results during Raman testing, possibly because the addition of excessive acetonitrile caused severe etching of the single-walled carbon nanotubes, resulting in more defects on their surface (defects refer to the decrease in the G / D ratio of the single-walled carbon nanotubes due to the reduced graphitization of the G peak and the increased defect level of the D peak when excessive acetonitrile is added).

[0062] Comparative Example 2

[0063] Same as Example 1, except that 45 mL of acetonitrile solution was added in step (1). The obtained single-walled carbon nanotubes had a purity of 75%, a diameter of 0.81 nm, and a G / D value of 44.4.

[0064] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for controlling the diameter of single-walled carbon nanotubes using acetonitrile, characterized in that, It is prepared by high-temperature calcination under inert gas protection, using toluene as the carbon source, thiophene as the catalyst, ferric chloride as the catalyst support, water as the solvent, and acetonitrile as the regulator. The specific steps of the method are as follows: ferric chloride, thiophene, water and acetonitrile solution are added to toluene and stirred to obtain a mixed solution; using nitrogen as a carrier, the mixed solution is injected into a high-temperature reactor to carry out the reaction to obtain a crude product; the crude product is purified to obtain pure single-walled carbon nanotubes. The volume ratio of the acetonitrile solution to toluene is (15-35):500; The volume ratio of the thiophene to the toluene is (5-30):500; The ratio of the amount of ferric chloride to the amount of toluene is 1 g: 50 mL.

2. The method for controlling the diameter of single-walled carbon nanotubes with acetonitrile according to claim 1, characterized in that, The injection rate of the mixed solution into the high-temperature reactor is 200-500 μL / min; the reaction temperature is 1100℃, and the heating rate is 5℃ / min.

3. The method for controlling the diameter of single-walled carbon nanotubes with acetonitrile according to claim 1, characterized in that, The purification process includes air oxidation and acid treatment. The specific steps are as follows: the crude product is calcined in air at 600°C for 2-3 hours, the calcined product is heated and stirred in a 6M acid solution, filtered, dried, and the dried product is further heated and stirred in a 6M acid solution.

4. The method for controlling the diameter of single-walled carbon nanotubes with acetonitrile according to claim 3, characterized in that, The heating and stirring refers to stirring at 100℃ for 24 hours.

5. The method for controlling the diameter of single-walled carbon nanotubes with acetonitrile according to claim 3, characterized in that, The acid solution is one or more of concentrated nitric acid, concentrated hydrochloric acid, and aqua regia.

6. The carbon nanotubes prepared by the method according to any one of claims 1-5, characterized in that, The diameter of the carbon nanotubes ranges from 0.88 to 1.87 nm.

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