A method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth
By mixing three-dimensional nanomaterials with metal salts in an ethanol solution and catalyzing the growth of carbon nanotubes in a tube furnace, the problems of complex high-temperature control and high cost in existing technologies have been solved. This has enabled the efficient and low-cost exfoliation of three-dimensional nanomaterials into two-dimensional nanosheets while preserving the crystal structure of the nanoparticles.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- QINGDAO UNIV OF SCI & TECH
- Filing Date
- 2026-04-22
- Publication Date
- 2026-06-30
AI Technical Summary
Existing three-dimensional nanomaterial exfoliation methods require precise gas control under high-temperature conditions. Mechanical exfoliation may result in insufficient exfoliation and low yield, while liquid phase exfoliation is costly. There is a lack of efficient and low-cost exfoliation technologies.
Three-dimensional nanomaterials, active metal salts, and auxiliary metal salts are dispersed in an ethanol solution, stirred evenly, and then calcined in a tube furnace while introducing hydrogen and a carbon source to catalyze the growth of carbon nanotubes, thereby achieving the exfoliation of two-dimensional nanosheets.
This method achieves efficient exfoliation of three-dimensional nanomaterials into two-dimensional nanosheets at a low cost, while preserving the crystal structure of small-sized nanoparticles and avoiding aggregation, resulting in high-purity two-dimensional nanosheets.
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Figure CN122301189A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanomaterials, specifically relating to a method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth. Background Technology
[0002] Three-dimensional nanomaterials possess high specific surface area. Their surfaces are in full contact with the environment, making them excellent support materials. Two-dimensional nanosheets exhibit unique properties, such as abundant reaction sites, ease of functionalization, and low loading difficulty. Two-dimensional nanosheets are widely used in catalysis and other fields.
[0003] Existing technologies commonly employ exfoliation methods such as chemical vapor deposition (CVD), mechanical exfoliation, and liquid phase exfoliation. CVD typically requires high temperatures and precise control of gas flow and reaction conditions, including parameters such as gas flow rate, temperature, and pressure. Mechanical exfoliation usually involves using mechanical force to break up the three-dimensional hollow alumina nanoflower-like material; this process can lead to incomplete exfoliation and relatively low yield, resulting in incomplete alumina nanosheets. Liquid phase exfoliation requires the introduction of organic solvents, with the exfoliating agent adhering to the surface of the alumina nanosheets, which is costly.
[0004] In summary, there is a need to develop a novel exfoliation method for exfoliating three-dimensional nanomaterials into two-dimensional nanosheets. Summary of the Invention
[0005] The purpose of this invention is to provide a method for exfoliating three-dimensional nanomaterials. The method involves dispersing three-dimensional nanomaterials, active metal salts, and auxiliary metal salts in an ethanol solution, stirring until homogeneous, transferring the solution to a ceramic boat, and calcining it in a tube furnace to obtain a precursor material. The precursor material is then ground and placed in a tube furnace. Under a nitrogen atmosphere, the furnace is heated while simultaneously introducing hydrogen and a carbon source to react for 1 hour. Subsequently, the hydrogen and propylene are turned off, and the furnace is cooled to room temperature to obtain carbon nanotubes and two-dimensional nanosheets.
[0006] The technical solution of this invention is: A method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth includes the following steps: Step 1: Mix the three-dimensional nanomaterials, active metal salts, auxiliary metal salts, and ethanol evenly to obtain a precursor solution; Step 2: Transfer the precursor solution into a ceramic boat, heat it to 500℃-700℃ in air atmosphere, calcine for 1 hour, and then cool it naturally to room temperature to obtain the precursor material. Step 3: Place the precursor material in a tube furnace and heat it to 660-800℃ in a nitrogen atmosphere. At the same time, introduce a mixture of reaction gas and reducing gas containing carbon source to catalyze the growth of metal-catalyzed carbon nanotubes. After the reaction is complete, stop the reaction and continue to cool under a protective atmosphere to obtain carbon nanotubes and exfoliated alumina two-dimensional nanosheets.
[0007] The mixing method in step one is as follows: Three-dimensional nanomaterials, active metal salts, and auxiliary metal salts are added to ethanol and stirred at a stirring speed of 200-400 r / min for 12-48 h to ensure that the components are mixed evenly.
[0008] The three-dimensional nanomaterials, active metal salts, and auxiliary metal salts are composed of the following raw materials in parts by weight: 30 parts oxide, 10-60 parts active metal salt, and 0.1-6 parts auxiliary metal salt.
[0009] The active metal salt includes any one or a combination of at least two of soluble iron salts, soluble nickel salts, and soluble cobalt salts.
[0010] The auxiliary metal salt includes any one or a combination of at least two of soluble molybdenum salt and soluble manganese salt.
[0011] The beneficial effects of this invention are: In this invention, the ethanol solution improves the charge distribution on the surface of the three-dimensional nanomaterial, allowing the active metal salt and auxiliary metal salt to be uniformly loaded onto the surface. The introduction of the auxiliary metal salt inhibits the aggregation of active metal salt nanoparticles on the carrier surface while enhancing their catalytic activity. Under high temperature conditions, the simultaneous introduction of hydrogen and a carbon source catalyzes the growth of carbon nanotubes. The grown carbon nanotubes then cause the two-dimensional nanosheets that make up the three-dimensional nanomaterial to disintegrate, thus achieving a peeling effect.
[0012] In the technical solution of this invention, the two-dimensional nanosheets after exfoliation are doped with carbon nanotubes, heated in an air atmosphere, the carbon nanotubes are pyrolyzed, and after cooling to room temperature, high-purity two-dimensional nanosheets are obtained.
[0013] It should be noted that in the exfoliation method described in this invention, during the process of catalyzing carbon nanotubes with catalytic metal, the crystal structure is in the process of evolving from an amorphous state to a crystalline state, which ensures the retention of small-sized nanoparticles and avoids their aggregation due to prolonged exposure to high temperatures.
[0014] As a technical method of the present invention, the active metal salt in step one includes any one or a combination of at least two of ferric nitrate, cobalt nitrate, and nickel nitrate.
[0015] Preferably, the auxiliary metal salt in step one includes any one or a combination of at least two of ammonium molybdate and sodium molybdate.
[0016] As a preferred technical solution of the present invention, the three-dimensional nanomaterial, active metal salt, auxiliary metal salt and ethanol in step one are mixed evenly. The stirring rate for even mixing is 200-400 r / min, such as 210 r / min, 220 r / min, 230 r / min, 240 r / min, 250 r / min, 260 r / min, 270 r / min, 280 r / min or 290 r / min, etc. The stirring time is 12-48h, such as 12h, 13h, 14h, 15h, 16h, 17h or 18h, etc., but is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0017] Preferably, the three-dimensional nanomaterial described in step one is a nanoflower structure.
[0018] As a preferred technical solution of the present invention, the temperature in the air atmosphere in step two is raised to 500℃-700℃, such as 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃ or 580℃, etc., but is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0019] Preferably, in step two, the temperature is raised to a specified temperature in an air atmosphere and maintained for 1 hour.
[0020] As a preferred technical solution of the present invention, the catalytic metal in step three includes a catalytically active metal and a co-catalyst metal.
[0021] Preferably, the catalytically active metal includes Fe.
[0022] Preferably, the co-catalyst metal includes Mo.
[0023] As a preferred technical solution of the present invention, step three involves heating to 660-800°C in a nitrogen atmosphere, such as 660°C, 670°C, 680°C, 690°C, 700°C, 710°C, or 720°C, but is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0024] Preferably, the heating rate is 10°C / min.
[0025] As a preferred technical solution of the present invention, step three involves simultaneously introducing a mixture of a reaction gas containing a carbon source and a reducing gas. The carbon source gas includes any one or a combination of at least two of propylene, methane, ethylene, and carbon monoxide.
[0026] Preferably, the flow rate ratio of carbon source, hydrogen, and carrier gas is 100:200:100. Attached Figure Description
[0027] Figure 1 SEM image of Example 1 (Scanning electron microscope image of the product prepared in Example 1); Figure 2 SEM image of Example 1 (Scanning electron microscope image of the product prepared in Example 1); Figure 3 The image shown is a TEM image of Example 1 (a transmission electron microscope image of the product prepared in Example 1). Figure 4 SEM image of Comparative Example 1 (SEM image of the product prepared in Comparative Example 1). Detailed Implementation
[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0029] Example 1 A method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth, the method comprising the following steps: (1) Take 1.51g Al(NO3)3·9H2O, 0.7g K2SO4, and 0.50g urea, dissolve them in deionized water and stir evenly. Transfer the solution to a 150ml polytetrafluoroethylene-lined hydrothermal reactor, react it hydrothermally at 180℃ for 3h, cool it to room temperature, filter it, dry the product at 80℃ for 12h and calcine it at 500℃ for 2h to obtain a three-dimensional nanomaterial composed of two-dimensional alumina nanosheets; (2) Dissolve 60 mg of ferric nitrate, 3 mg of sodium molybdate and 30 mg of the three-dimensional nanomaterial described in step (1) in 1 ml of ethanol solution, and stir at a rate of 200 r / min for 24 h to obtain a precursor solution; (3) The precursor solution was transferred to a tube furnace and heated from room temperature to 500°C at 10°C / min in an air atmosphere. The temperature was maintained for 1 hour and then naturally cooled to room temperature to obtain the precursor material. (4) The precursor material was placed in a tube furnace and heated to 660°C under a nitrogen atmosphere. Hydrogen and propylene were introduced at flow rates of 200 sccm for nitrogen, 200 sccm for hydrogen, and 100 sccm for propylene. After reacting for 1 hour, the mixture was cooled to room temperature to obtain carbon nanotubes and two-dimensional sheet-like nanomaterials. Figure 1 Figure 2 Figure 3 (As shown)
[0030] Example 2 A method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth, the method comprising the following steps: (1) Take 1.51g Al(NO3)3·9H2O, 0.7g K2SO4, and 0.50g urea, dissolve them in deionized water and stir evenly. Transfer the solution to a 150ml polytetrafluoroethylene-lined hydrothermal reactor, react it hydrothermally at 180℃ for 3h, cool it to room temperature, filter it, dry the product at 80℃ for 12h and calcine it at 500℃ for 2h to obtain a three-dimensional nanomaterial composed of two-dimensional alumina nanosheets; (2) Dissolve 60 mg of ferric nitrate, 6 mg of sodium molybdate and 30 mg of the three-dimensional nanomaterial described in step (1) in 1 ml of ethanol solution, and stir at a rate of 200 r / min for 24 h to obtain a precursor solution; (3) The precursor solution was transferred to a tube furnace and heated from room temperature to 500°C at 10°C / min in an air atmosphere. The temperature was maintained for 1 hour and then naturally cooled to room temperature to obtain the precursor material. (4) The precursor material was placed in a tube furnace and heated to 700°C in a nitrogen atmosphere. Hydrogen and propylene were introduced. The flow rate of nitrogen was 200 sccm, the flow rate of hydrogen was 200 sccm, and the flow rate of propylene was 100 sccm. After reacting for 1 hour, the mixture was cooled to room temperature to obtain carbon nanotubes and two-dimensional sheet nanomaterials.
[0031] Example 3 A method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth, the method comprising the following steps: (1) Take 1.51g Al(NO3)3·9H2O, 0.7g K2SO4, and 0.50g urea, dissolve them in deionized water and stir evenly. Transfer the solution to a 150ml polytetrafluoroethylene-lined hydrothermal reactor, react it hydrothermally at 180℃ for 3h, cool it to room temperature, filter it, dry the product at 80℃ for 12h and calcine it at 500℃ for 2h to obtain a three-dimensional nanomaterial composed of two-dimensional alumina nanosheets; (2) Dissolve 70 mg of ferric nitrate, 2 mg of sodium molybdate and 30 mg of the three-dimensional nanomaterial described in step (1) in 1 ml of ethanol solution, and stir at a rate of 200 r / min for 24 h to obtain a precursor solution; (3) The precursor solution was transferred to a tube furnace and heated from room temperature to 600°C at 10°C / min in an air atmosphere. The temperature was maintained for 1 hour and then naturally cooled to room temperature to obtain the precursor material. (4) The precursor material was placed in a tube furnace and heated to 750°C in a nitrogen atmosphere. Hydrogen and propylene were introduced. The flow rate of nitrogen was 100 sccm, the flow rate of hydrogen was 100 sccm, and the flow rate of propylene was 50 sccm. After reacting for 1 hour, the mixture was cooled to room temperature to obtain carbon nanotubes and two-dimensional sheet nanomaterials.
[0032] Comparative Example 1 The anhydrous ethanol in Example 1 was replaced with an equal amount of deionized water, and all other preparation steps were the same as in Example 1. Figure 4 ) Comparative Example 2 The three-dimensional nanomaterials in Example 1 were replaced with an equal amount of solid alumina spheres, and all other preparation steps were the same as those in Example 1.
[0033] (1) In Examples 1-3, adjusting the auxiliary metal, active metal component, carbon source flow rate, and synthesis temperature can achieve the exfoliation of three-dimensional nanomaterials.
[0034] (2) When ethanol or spherical alumina was used instead of alternating three-dimensional nanomaterials or ethanol in Comparative Examples 1-2, the two-dimensional nanosheets could not be exfoliated.
[0035] (4) Adjusting the auxiliary metal, active metal component, carbon source flow rate and synthesis temperature can achieve the exfoliation of three-dimensional nanomaterials; however, when changing the solvent or using nanomaterials composed of non-two-dimensional nanosheets, the exfoliation of three-dimensional nanomaterials cannot be achieved; therefore, the realization of this exfoliation strategy depends on the uniform loading of the catalyst on the surface of the support, and the carbon nanotubes catalyze the exfoliation of flower-like and layered three-dimensional nanomaterials into two-dimensional nanosheets.
[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, alterations, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth, characterized in that, High-density, high-activity, and small-size catalysts are loaded on the surface and interstices of three-dimensional nanomaterials, and energy, carbon source, H2, and Ar are provided to the three-dimensional nanomaterials in the reactor to activate the catalyst to grow high-density, small-diameter carbon nanotubes, thereby enabling the two-dimensional nanosheets that make up the three-dimensional nanomaterials to be exfoliated. The two-dimensional nanosheets include at least one of silicon oxide, aluminum oxide, and magnesium oxide; The three-dimensional nanostructure includes at least one of nanoflowers and nanolayers; The three-dimensional nanomaterial is composed of two-dimensional nanosheets; The three-dimensional nanomaterials are obtained through hydrothermal and solvothermal chemical reactions. The energy is provided by means of indirect heating of the three-dimensional nanomaterial, wherein the indirect heating is direct heating of the reactor to generate heat in the substrate through thermal radiation or thermal convection.
2. As described in claim 1, characterized in that, The exfoliation method uses three-dimensional nanomaterials as a substrate, active metals as catalytic metals, and auxiliary metals as reinforcing agents to prepare small-diameter, high-density carbon nanotubes, and then exfoliates the three-dimensional nanomaterials. The steps include: Step 1: Mix the three-dimensional nanomaterials, active metal salts, auxiliary metal salts, and ethanol evenly to obtain a precursor solution; Step 2: Transfer the precursor solution into a ceramic boat, heat it to 500℃-700℃ in air atmosphere, calcine for 1 hour, and then cool it naturally to room temperature to obtain the precursor material. Step 3: Place the precursor material in a tube furnace and heat it to 660-800℃ in a nitrogen atmosphere. At the same time, introduce a mixture of reaction gas and reducing gas containing carbon source to catalyze the growth of metal-catalyzed carbon nanotubes. After the reaction is complete, stop the reaction and continue to cool under a protective atmosphere to obtain carbon nanotubes and exfoliated alumina two-dimensional nanosheets. The mixing method in step one is as follows: Three-dimensional nanomaterials, active metal salts, and auxiliary metal salts are added to ethanol and stirred at a speed of 200-400 r / min for 12-48 h to ensure that the components are mixed evenly. The three-dimensional nanomaterial, active metal salt, and auxiliary metal salt are composed of the following raw materials in parts by weight: 30 parts oxide, 10-60 parts active metal salt, and 0.1-6 parts auxiliary metal salt; The active metal salt includes any one or a combination of at least two of soluble iron salts, soluble nickel salts, and soluble cobalt salts; The auxiliary metal salt includes any one or a combination of at least two of soluble molybdenum salt and soluble manganese salt.
3. The method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth according to claim 2, characterized in that, In step one, the preferred three-dimensional nanomaterial is a three-dimensional flower-shaped nanomaterial composed of two-dimensional alumina nanosheets.
4. The method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth according to claim 2, characterized in that, The preparation steps of the three-dimensional flower-like nanomaterial composed of alumina two-dimensional nanosheets are as follows: Aluminum nitrate, urea, and potassium sulfate were added to a container containing deionized water and mixed thoroughly. The solution was then transferred to a polytetrafluoroethylene-lined hydrothermal reactor and hydrothermally reacted at 180°C for 3 hours. After cooling to room temperature, the product was filtered, dried, and calcined to obtain a three-dimensional flower-like nanomaterial composed of two-dimensional alumina nanosheets.
5. The method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth according to claim 2, characterized in that, In step one, the ratio of ethanol to three-dimensional nanomaterials, active metal salts and auxiliary metal salts is (1-2 mL): (40-96 parts).
6. The method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth according to claim 2, characterized in that, In step two, the optimal calcination temperature under air atmosphere is 500℃ for 1 hour.
7. The method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth according to claim 2, characterized in that, In step three, the flow rate ratio of nitrogen, hydrogen, and carbon source gas is 200:200:100 to ensure that the carrier gas is supplied throughout the process. Preferably, the carbon source gas includes any one or a combination of at least two of ethylene, propylene, or propane; Preferably, the carrier gas includes nitrogen and / or argon.
8. The method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth according to claim 2, characterized in that, The catalytic metal mentioned in step three includes catalytically active metals and co-catalyst metals; Preferably, the catalytically active metal includes Fe; Preferably, the co-catalyst metal includes Mo.
9. The method for exfoliating three-dimensional nanomaterials based on carbon nanotube growth according to claim 2, characterized in that, The catalytic metal described in step three has a crystal structure.