A method for preparing ultra-small carbon nanorods

Abstract

This invention discloses a method for preparing ultrasmall carbon nanorods. The specific steps are as follows: using a solvent method, imidazole ionic liquid as the raw material and a mixed solution of sulfuric acid and ethanol as the solvent; dissolving the imidazole ionic liquid in the mixed solution of sulfuric acid and ethanol, and uniformly mixing to obtain a reaction solution; reacting the reaction solution under sealed conditions at 180-250℃ for 10-25 h; after cooling to room temperature, the resulting solution is processed through neutralization, centrifugation, rotary evaporation, extraction, and vacuum drying to obtain solid ultrasmall carbon nanorods. The method for preparing ultrasmall carbon nanorods provided by this invention can conveniently prepare ultrasmall carbon nanorods with a particle size in the nanometer range. More importantly, the size of the ultrasmall carbon nanorods can be controlled by adjusting reaction parameters such as the type of imidazole ionic liquid, reaction temperature, and reaction time. This invention solves the problems of cumbersome preparation processes and the inability to control the size of ultrasmall carbon nanorods.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical and material science, and particularly relates to a method for preparing ultra-small carbon nanorods. BACKGROUND

[0002] Carbon nanomaterials have attracted extensive attention in the field of chemical and material science due to their unique physical and chemical properties. Among them, carbon nanorods, as an important carbon nanomaterial, have wide application prospects in the fields of nanoelectronics, energy storage, catalysts and biomedicine. Traditional methods for preparing carbon nanorods are multi-step and complex, which limits their large-scale preparation and commercial application. In recent years, researchers have proposed some single-step methods for preparing carbon nanorods. For example, Zhang Qin's team used sulfur powder and thiophene as carbon sources to directly heat in a stainless steel autoclave to synthesize carbon nanorods with a length of about 300 nm (Carbon, 2023, 201, 776-784); Andrey L. Rogach's group used citric acid as a carbon source and used the surfactant aminopropyl isobutyl silsesquioxane as an encapsulating agent to synthesize carbon nanorods with a length of 50 nm and a width of 20 nm by a solvothermal method (ACS Nano, 2019, 13(10), 12024-12031). The above literatures show that the carbon nanorods prepared by the existing methods have large diameter and length, and the length is mostly more than 50 nm. Meanwhile, the preparation process is complicated, which increases the preparation cost. Therefore, it is necessary to develop a simple and efficient method for preparing ultra-small carbon nanorods to overcome the problems existing in the prior art. The newly developed method should have the following characteristics: adjustable diameter and length of ultra-small carbon nanorods, low cost, and no need for expensive catalysts or rare metals. SUMMARY

[0003] The present application provides a novel method for preparing ultra-small carbon nanorods, which is simple and efficient to prepare ultra-small carbon nanorods in one step to overcome the above problems.

[0004] In order to achieve the above purpose, the technical scheme of the present application is as follows:

[0005] A method for preparing ultra-small carbon nanorods, the specific steps are as follows: using a solvent method, using imidazole ionic liquid as a raw material, and using a mixed solution of sulfuric acid and ethanol as a solvent; dissolving the imidazole ionic liquid in the mixed solution of sulfuric acid and ethanol, uniformly mixing the raw material and the solvent by ultrasonic method to obtain a reaction solution; under the condition of 180-250 DEG C of the reaction solution, namely, adding to the inner lining of polytetrafluoroethylene autoclave reaction for 10-25 h; after cooling to room temperature, the obtained solution is treated by sodium hydroxide neutralization, high-speed centrifugation of centrifuge, rotary evaporation (the purpose is to remove excess ethanol), extraction and vacuum drying process to obtain solid ultra-small carbon nanorods.

[0006] The method for preparing ultra-small carbon nanorods according to the above, characterized in that the imidazole ionic liquid is one or more of 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium nitrate, 1-ethyl-3-methylimidazolium bromide, 1-carboxymethyl-3-methylimidazolium chloride, 1-carboxymethyl-3-methylimidazolium nitrate, 1-carboxymethyl-3-methylimidazolium bromide, 1-allyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium nitrate and 1-allyl-3-methylimidazolium bromide.

[0007] The method for preparing ultra-small carbon nanorods according to the above, characterized in that the mass ratio of the imidazole ionic liquid and the mixed solution of sulfuric acid and ethanol is 0.1-0.5:1.

[0008] The method for preparing ultra-small carbon nanorods according to the above, characterized in that the volume ratio of the sulfuric acid and ethanol is 0.1-0.2:1.

[0009] The method for preparing ultra-small carbon nanorods according to the above, characterized in that the extraction process uses ethyl acetate extraction.

[0010] Compared with the prior art, the method for preparing ultra-small carbon nanorods according to the present application has the following beneficial effects:

[0011] The method for preparing ultra-small carbon nanorods according to the present application solves the problems of complicated preparation process and inability to realize size control of ultra-small carbon nanorods, and can realize efficient preparation of ultra-small carbon nanorods through a new preparation process and material combination, has scalability and economy, and provides a broader application prospect for carbon nanorods. BRIEF DESCRIPTION OF DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0013] Figure 1 The image of the ultra-small carbon nanorod 1 under a transmission electron microscope (TEM) disclosed in the embodiments of the present application;

[0014] Figure 2 The image of the ultra-small carbon nanorod 1 under an atomic force microscope (AFM) disclosed in the embodiments of the present application;

[0015] Figure 3 The height distribution graph along the white line in the AFM image of the ultra-small carbon nanorod 1 disclosed in the embodiments of the present application;

[0016] Figure 4 is an image under TEM of the ultra-small carbon nanorod 2;

[0017] Figure 5 is an AFM image of the ultra-small carbon nanorod 2;

[0018] Figure 6 is a height distribution graph along the white line in the AFM image of the ultra-small carbon nanorod 2;

[0019] Figure 7 is an image under TEM of the ultra-small carbon nanorod 3;

[0020] Figure 8 is an AFM image of the ultra-small carbon nanorod 3;

[0021] Figure 9 is a height distribution graph along the white line in the AFM image of the ultra-small carbon nanorod 3. DETAILED DESCRIPTION

[0022] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0023] Embodiment:

[0024] The embodiment provides a preparation method of the ultra-small carbon nanorod 1, and the specific steps are as follows: 0.8 g of 1-ethyl-3-methyl imidazole bromide is used as a raw material, 6 mL of a sulfuric acid and ethanol mixed solution (the volume ratio of sulfuric acid to ethanol is 1:5) is added, and ultrasonic treatment is performed to uniformly mix the solution as a reaction solution; the reaction solution is added to a polytetrafluoroethylene-lined reaction kettle, and then the reaction kettle is placed in a forced air drying oven, heated at 230°C for 20 h; cooled to room temperature, the obtained solution is mixed with a 1 mol / L sodium hydroxide solution for neutralization; then a centrifuge is used to centrifuge at a speed of 8000 revolutions per minute for 0.5 h to remove large particles; next, the supernatant after centrifugation is concentrated by a rotary evaporator to remove ethanol in the solvent, and the product is extracted from the solution by using ethyl acetate; finally, the obtained solution after treatment is freeze-dried to obtain solid-state ultra-small carbon nanorod 1.

[0025] In order to verify the size of the ultra-small carbon nanorod 1, TEM characterization (as shown in Figure 1 , AFM characterization (as shown in Figure 2 , and a height distribution graph along the white line in the AFM image (as shown in Figure 3The length / width of the product is 32.81 / 11.51 nm, and the thickness is 10.57 nm.

[0026] Example 2

[0027] The present example provides a preparation method of the ultra-small carbon nanorod 2, and the specific steps are as follows: 0.8 g of 1-ethyl-3-methylimidazole chloride salt is used as a raw material, 6 mL of a sulfuric acid-ethanol mixed solution (the volume ratio of sulfuric acid to ethanol is 1:5) is added, and ultrasonic treatment is performed to uniformly mix the solution as a reaction solution; the reaction solution is added to a polytetrafluoroethylene-lined reaction kettle, and then the reaction kettle is placed in a blast drying oven, heated at 230°C for 20 h; cooled to room temperature, mixed with 1 mol / L sodium hydroxide solution for neutralization; then centrifuged at 8000 rpm for 0.5 h using a centrifuge to remove large particles; next, the supernatant after centrifugation is concentrated by a rotary evaporator to remove ethanol in the solvent, and the product is extracted from the solution using ethyl acetate; finally, the treated solution is freeze-dried to obtain solid ultra-small carbon nanorod 2.

[0028] In order to verify the size of the ultra-small carbon nanorod 2, TEM characterization (as shown in Figure 4 , AFM characterization (as shown in Figure 5 , and the height distribution graph along the white line in the AFM image (as shown in Figure 6 ) are performed, and the length / width of the product is 20.91 / 13.81 nm, and the thickness is 8.78 nm.

[0029] Example 3

[0030] The present example provides a preparation method of the ultra-small carbon nanorod 3, and the specific steps are as follows: 0.8 g of 1-ethyl-3-methylimidazole nitrate is used as a raw material, 6 mL of a sulfuric acid-ethanol mixed solution (the volume ratio of sulfuric acid to ethanol is 1:5) is added, and ultrasonic treatment is performed to uniformly mix the solution as a reaction solution; the reaction solution is added to a polytetrafluoroethylene-lined reaction kettle, and then the reaction kettle is placed in a blast drying oven, heated at 230°C for 20 h; cooled to room temperature, mixed with 1 mol / L sodium hydroxide solution for neutralization; then centrifuged at 8000 rpm for 0.5 h using a centrifuge to remove large particles; next, the supernatant after centrifugation is concentrated by a rotary evaporator to remove ethanol in the solvent, and the product is extracted from the solution using ethyl acetate; finally, the treated solution is freeze-dried to obtain solid ultra-small carbon nanorod 3.

[0031] In order to verify the size of the ultra-small carbon nanorod 3, TEM characterization (as shown in Figure 7 , AFM characterization (as shown in Figure 8and the height profile along the white line in the AFM image (as shown in the right panel) of the product is 28.95 / 15.29 nm in length / width and 6.02 nm in thickness. Figure 9 and the height profile along the white line in the AFM image (as shown in the right panel) of the product is 28.95 / 15.29 nm in length / width and 6.02 nm in thickness.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing ultra-small carbon nanorods, comprising the following steps: using a solvent method, taking an imidazole ionic liquid as a raw material, and taking a mixed solution of sulfuric acid and ethanol as a solvent; dissolving the imidazole ionic liquid in the mixed solution of sulfuric acid and ethanol, uniformly mixing to obtain a reaction solution; reacting the reaction solution under a sealed condition at 180-250 ℃ for 10-25 h; after cooling to room temperature, treating the obtained solution through a process of neutralization, centrifugation, rotary evaporation, extraction and vacuum drying to obtain solid ultra-small carbon nanorods; the imidazole ionic liquid is one or more of 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium nitrate, 1-ethyl-3-methylimidazolium bromide, 1-carboxymethyl-3-methylimidazolium chloride, 1-carboxymethyl-3-methylimidazolium nitrate, 1-carboxymethyl-3-methylimidazolium bromide, 1-allyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium nitrate and 1-allyl-3-methylimidazolium bromide.

2. The method for preparing ultrasmall carbon nanorods according to claim 1, characterized in that, The imidazole ionic liquid is one or more of 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium nitrate, 1-ethyl-3-methylimidazolium bromide, 1-allyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium nitrate and 1-allyl-3-methylimidazolium bromide.

3. The method of claim 1, wherein the carbon nanorod is less than 5 nm in diameter. The mass ratio of the imidazole ionic liquid to the mixed solution of sulfuric acid and ethanol is 0.1-0.5:

1.

4. The method of claim 1 or 3, wherein the method is characterized by, The volume ratio of the sulfuric acid to the ethanol is 0.1-0.2:

1.

5. The method of claim 1, wherein the carbon nanorod is less than 5 nm in diameter. The extraction process uses ethyl acetate extraction.

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