A method for macroscopic preparation of two-dimensional nanosheets based on external field coupling technology
The continuous airflow jet spinning method using external field coupling technology has solved the problem of large-scale production of two-dimensional nanosheets, realizing efficient and simple nanosheet preparation and structure control, which is suitable for catalyst design.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SOUTHEAST UNIV
- Filing Date
- 2025-08-05
- Publication Date
- 2026-07-21
AI Technical Summary
Existing technologies are insufficient for the large-scale production of two-dimensional nanosheets. Furthermore, existing methods are complex, costly, and environmentally unfriendly, and it is difficult to precisely control the structure and pore distribution of nanosheets.
Two-dimensional nanosheets were prepared by using external field coupling technology and continuous airflow jet spinning method, with parameters such as air pressure, solution flow rate and needle diameter controlled, avoiding high temperature and high pressure and toxic reagents, and simplifying the operation process.
It enables the large-scale, economical, and convenient preparation of two-dimensional nanosheets. The fine structure of the nanosheets can be controlled by simple parameter adjustment, thereby improving preparation efficiency and yield, and is suitable for catalyst design.
Smart Images
Figure CN121107448B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of external field coupling and mass production technology of two-dimensional nanosheets, specifically relating to a continuous airflow coupling technology, and more particularly to a method for mass production of two-dimensional nanosheets by changing parameters such as air pressure, flow rate and needle diameter. Background Technology
[0002] Two-dimensional nanosheets, due to their unique physicochemical properties such as high specific surface area, excellent oxygen storage capacity, reversible surface oxygen ion exchange characteristics, and high thermal stability, have become ideal carriers for catalyst design. Among them, cerium dioxide (CeO2) nanosheets, as rare earth metal oxides, have significant application value in fields such as carbon dioxide reduction, photocatalysis, tail gas treatment, and water purification. Currently, the laboratory preparation of two-dimensional nanosheets mainly faces technical bottlenecks in large-scale production: existing methods, such as oleic acid-assisted methods, solution self-assembly methods, and graphene template methods, generally suffer from complex operating procedures and stringent environmental requirements. They rely on high-temperature and high-pressure conditions or precise control of multiple parameters (such as surfactant concentration, pH value, and reaction temperature gradient), resulting in low preparation efficiency and difficulty in scaling up. For example, traditional template methods require the use of expensive materials such as graphene and involve multiple etching steps, while the oleic acid method involves high-temperature treatment with toxic organic solvents, which not only increases costs and safety risks but also limits the batch preparation of products. At the macro-level, existing technologies struggle to balance yield and structural controllability. On one hand, methods like mechanical exfoliation and liquid-phase exfoliation only achieve milligram-level production, with poor product size uniformity. On the other hand, while hydrothermal / solvothermal methods can increase yield, the reactor volume limits the scale of single-batch preparation, and the high-temperature, high-pressure environment exacerbates energy consumption and equipment burden. More critically, existing methods lack the ability to control the fine structure of nanosheets (such as pore distribution, thickness, and crystal orientation), often requiring changes to the template type or reconstruction of the reaction system, and lacking the technical means to achieve structural diversification through simple parameter adjustments. Therefore, developing a simple, cost-effective, and environmentally friendly macro-preparation technology that can obtain different types of two-dimensional nanosheets and precisely control their hierarchical pore structure by adjusting only a few key parameters, while avoiding high temperature, high pressure, and toxic reagents, has become a pressing technical challenge in this field. Summary of the Invention
[0003] Technical problem solved: In response to the above-mentioned technical problem, this invention provides a method for the large-scale preparation of two-dimensional nanosheets based on external field coupling technology, which realizes the large-scale, economical, efficient, convenient and simple preparation and application of two-dimensional nanosheets.
[0004] Technical solution: A method for mass production of two-dimensional nanosheets based on external field coupling technology, comprising the following steps: (1) dissolving polyvinylpyrrolidone (PVP) with a molecular weight of 1,300,000 in anhydrous ethanol and stirring at 190-210 rpm to form a uniform and transparent solution; (2) adding acetone and a metal precursor salt to the solution in step (1) and continuing to stir to obtain a uniform and stable precursor solution; wherein the metal precursor salt includes acetylacetone salt or tetraisopropyl titanate; (3) performing air-jet spinning of the precursor solution through a 19-23G needle, with an air-jet pressure of 2-7 bar, a solution flow rate of 5-80 mL / h, and a distance of 30 cm between the needle and the nonwoven fabric receiver to obtain composite nanosheets; (4) calcining the composite nanosheets in an air atmosphere at 4.1-4.3℃ / min to 500-600℃ to obtain multi-level porous metal oxide two-dimensional nanosheets.
[0005] In step (1), the ratio of polyvinylpyrrolidone to anhydrous ethanol is 0.6 g: 3 mL.
[0006] The acetylacetone salt mentioned in step (2) is cerium acetylacetone or iron acetylacetone.
[0007] In step (2), the amount of acetone added is 3 mL and the amount of metal precursor salt added is 0.3 g.
[0008] In step (3), the gas injection pressure is 7 bar and the solution flow rate is 20 mL / h.
[0009] The needle mentioned in step (3) is 23G.
[0010] In step (4), the calcination environment is an air atmosphere in a muffle furnace.
[0011] In step (3), the air-jet spinning environment temperature is 25℃ and the ambient humidity is less than 40%.
[0012] The two-dimensional nanosheets prepared by the above method are CeO2, Fe2O3, TiO2, Al2O3 or MgO nanosheets.
[0013] An application of an external field coupling technique in the preparation of two-dimensional nanosheets, wherein the fine structure of the nanosheets is controlled by the above method, and the external field coupling technique is continuous airflow airjet spinning.
[0014] Beneficial Effects: This invention utilizes external field coupling technology for the large-scale preparation of two-dimensional nanosheets. Traditional methods for preparing two-dimensional nanosheets rely heavily on the control of multiple parameters, complex operational procedures, and highly technical processes. Furthermore, the yield and quality of nanosheets are low, creating a bottleneck in large-scale preparation. The method of this invention is convenient, efficient, and produces readily available products, enabling large-scale preparation and aligning with green and environmentally friendly production principles. This invention allows for the control of the fine structure of two-dimensional nanosheets by introducing a continuous airflow external field and changing only three parameters: air pressure, solution flow rate, and needle diameter.
[0015] This invention can obtain different two-dimensional nanosheets by changing the type of metal precursor salt to meet various production needs. It is simple, flexible, and facilitates the design and formulation of catalysts.
[0016] This invention optimizes the process by using a simple air-blowing method to replace traditional synthesis methods, including those using oleic acid, in-solution assembly, and graphene templates, which mostly involve high-temperature and high-pressure operating conditions. This invention improves the efficiency of two-dimensional nanosheet preparation. Attached Figure Description
[0017] Figure 1 Flowchart for the gas-jet fabrication of nanosheets.
[0018] Figure 2 Simulation images of air-jet spinning under different air pressures and TEM images of the corresponding cerium oxide nanosheet products.
[0019] Figure 3 This is a diagram showing the diameter distribution of cerium oxide nanosheets at different precursor liquid flow rates.
[0020] Figure 4 Simulation images of air-jet spinning at different precursor liquid flow rates and TEM images of the corresponding cerium oxide nanosheet products.
[0021] Figure 5 Physical images of Ce(acac)3 / PVP composite nanosheets obtained with needles of different specifications on the receiver.
[0022] Figure 6 This is a TEM image of two-dimensional Fe2O3 nanosheets.
[0023] Figure 7 TEM images and elemental distribution maps of high-entropy oxide nanosheets prepared from five metal precursor salts.
[0024] Figure 8 A weight representation of the mass production of two-dimensional nanosheets.
[0025] Figure 9 This is a schematic diagram of the BET test results in Example 1.
[0026] Figure 10 This is a schematic diagram of the BET test results in Example 2.
[0027] Figure 11 This is a schematic diagram of the BET test results in Example 3.
[0028] Figure 12 This is a schematic diagram of the BET test results in Example 4. Detailed Implementation
[0029] Example 1
[0030] Preparation of cerium dioxide nanosheets with different fine structures by changing the air pressure of the external field of a continuous airflow:
[0031] First, accurately weigh 0.6g of polyvinylpyrrolidone (PVP, Mw≈1.3×10⁻⁶). 6 Dissolve the metal precursor salt in 3 mL of ethanol, adjust the magnetic stirrer speed to 200 rpm, and stir overnight at room temperature to obtain a uniform and transparent solution. Then, add 3 mL of acetone and 0.3 g of cerium acetylacetone (Ce(acac)3) to the above solution in sequence, and stir at room temperature for 4 h to completely dissolve the metal precursor salt and obtain a uniform and stable gas-sprayed precursor solution.
[0032] The precursor solution was transferred to a 5mL syringe. Using a 23G needle, the precursor solution was blown out at a flow rate of 20mL / h under three different air pressures: 0.2MPa, 0.4MPa, and 0.5MPa. The receiver was made of nonwoven fabric, and the distance between the metal needle and the receiver was 30cm. The ambient temperature for air-jet spinning was maintained at room temperature of 25℃, and the humidity was controlled below 40%.
[0033] The sample obtained by gas spraying was placed in an air atmosphere in a muffle furnace, heated to 500℃ at a heating rate of 4.2℃ / min and calcined for 2h to remove the polyvinylpyrrolidone polymer template, thus preparing CeO2 two-dimensional nanosheets with different fine structures.
[0034] The gas-jet product obtained under a pressure of 0.5 MPa was subjected to BET testing, and the resulting adsorption curve is shown below. Figure 9As shown, the physical quantities in the graph are interpreted as follows: the horizontal axis represents the diameter of the pore; dV(d) is the rate of change of pore volume, reflecting the increase in pore volume corresponding to a unit change in pore diameter; and Cumulative Pore Volume is the total pore volume, reflecting the sum of the volumes of all pores smaller than a certain pore diameter. As the pore diameter gradually increases, the cumulative pore volume also increases. When the pore diameter reaches its maximum value of 84.58 nm, the cumulative pore volume is 0.21 cc / g, which is the total pore volume of the material. When the pore diameter is 2.719 nm, dV(d) reaches its maximum value of 0.02713 cc / nm / g, indicating that the pore volume growth rate corresponding to this pore diameter is the largest, reflecting that this pore diameter contributes the most to the total pore volume and is the most numerous, dominating among all pore diameters.
[0035] In summary, the total surface area of this material is 139.824 m². 2 / g, total pore volume is 0.21cc / g, and most probable pore size is 2.719nm.
[0036] Example 2
[0037] Cerium dioxide nanosheets with different fine structures were prepared by changing the solution flow rate of the precursor solution:
[0038] First, accurately weigh 0.6g of polyvinylpyrrolidone (PVP, Mw≈1.3×10⁻⁶). 6 Dissolve the metal precursor salt in 3 mL of ethanol, adjust the magnetic stirrer speed to 200 rpm, and stir overnight at room temperature to obtain a uniform and transparent solution. Then, add 3 mL of acetone and 0.3 g of cerium acetylacetone (Ce(acac)3) to the above solution in sequence, and stir at room temperature for 4 h to completely dissolve the metal precursor salt and obtain a uniform and stable gas-sprayed precursor solution.
[0039] The precursor solution was transferred to a 5mL syringe. Using a 23G needle, the precursor solution was blown out at four different flow rates of 5mL / h, 20mL / h, 40mL / h, and 80mL / h under a pressure of 7bar. The receiver was made of nonwoven fabric, and the distance between the metal needle and the receiver was 30cm. The ambient temperature of the air-jet spinning was maintained at room temperature of 25℃, and the humidity was controlled below 40%.
[0040] The sample obtained by gas spraying was placed in an air atmosphere in a muffle furnace, heated to 500℃ at a heating rate of 4.2℃ / min and calcined for 2h to remove the polyvinylpyrrolidone polymer template, thus preparing CeO2 two-dimensional nanosheets with different fine structures.
[0041] The gas-jet product obtained at a flow rate of 40 mL / h was subjected to BET testing, and the resulting adsorption curve is shown below. Figure 10As shown, the cumulative pore volume increases with the gradual increase of pore size. When the pore size reaches its maximum value of 87.14 nm, the cumulative pore volume is 0.124 cc / g, which is the total pore volume of the material. When the pore size is 2.725 nm, dV(d) reaches its maximum value of 0.01458 cc / nm / g, indicating that the pore volume growth rate corresponding to this pore size is the largest, reflecting that this pore size contributes the most to the total pore volume and is the most numerous, dominating among all pore sizes.
[0042] In summary, the total surface area of this material is 81.556 m². 2 / g, total pore volume is 0.124cc / g, and most probable pore size is 2.725nm.
[0043] Example 3
[0044] Cerium dioxide nanosheets with different fine structures were prepared by changing the needle tip thickness:
[0045] First, accurately weigh 0.6g of polyvinylpyrrolidone (PVP, Mw≈1.3×10⁻⁶). 6 Dissolve the metal precursor salt in 3 mL of ethanol, adjust the magnetic stirrer speed to 200 rpm, and stir overnight at room temperature to obtain a uniform and transparent solution. Then, add 3 mL of acetone and 0.3 g of cerium acetylacetone (Ce(acac)3) to the above solution in sequence, and stir at room temperature for 4 h to completely dissolve the metal precursor salt and obtain a uniform and stable gas-sprayed precursor solution.
[0046] The precursor solution was transferred to a 5mL syringe. Using two different needles, 19G and 23G, the precursor solution was blown out at a flow rate of 20mL / h under a pressure of 7bar. The receiver was made of nonwoven fabric. The distance between the metal needle and the receiver was 30cm. The ambient temperature of the air-jet spinning was maintained at room temperature of 25℃ and the humidity was controlled below 40%.
[0047] The sample obtained by gas spraying was placed in an air atmosphere in a muffle furnace, heated to 500℃ at a heating rate of 4.2℃ / min and calcined for 2h to remove the polyvinylpyrrolidone polymer template, thus preparing CeO2 two-dimensional nanosheets with different fine structures.
[0048] The gas-jet product obtained under conditions with a needle diameter of 23G was subjected to BET testing, and the resulting adsorption-desorption curves are shown below. Figure 11 As shown, the nitrogen adsorption isotherm exhibits typical Type IV characteristics, indicating that the material has significant mesoporous features. The accompanying H1-type hysteresis loop indicates that the sample possesses a highly uniform cylindrical mesoporous structure with a concentrated pore size distribution. The isotherm begins to close at P / P0≈0.4, indicating the absence of interference from micropores or slit pores. The curves coincide in the low-pressure region, demonstrating good adsorption reversibility.
[0049] Example 4
[0050] Preparation of two-dimensional iron oxide nanosheets by changing the type of metal precursor salt:
[0051] First, accurately weigh 0.4g of polyvinylpyrrolidone (PVP, Mw≈1.3×10⁻⁶). 6 Dissolve the metal precursor salt in 3 mL of ethanol, adjust the magnetic stirrer speed to 200 rpm, and stir overnight at room temperature to obtain a uniform and transparent solution. Then add 3.5 mL of glacial acetic acid and mix evenly with a vortex mixer. Add 0.8 g of acetylacetone iron (Fe(acac)3) and continue stirring at room temperature to completely dissolve the metal precursor salt and form a uniform and stable orange-red gas spray precursor solution.
[0052] The precursor solution was transferred to a 5mL syringe. Using a 23G needle, the precursor solution was blown out at a flow rate of 20mL / h under a pressure of 7bar. The receiver was made of nonwoven fabric. The distance between the metal needle and the receiver was 30cm. The ambient temperature for air-jet spinning was maintained at room temperature of 25℃ and the humidity was controlled below 40%.
[0053] The sample obtained by gas spraying was placed in an air atmosphere in a muffle furnace, heated to 500℃ at a heating rate of 4.2℃ / min and held for calcination for 2h to remove the polyvinylpyrrolidone polymer template and prepare Fe2O3 two-dimensional nanosheets.
[0054] BET tests were performed on Fe2O3 two-dimensional nanosheets, and the resulting adsorption-desorption curves are shown below. Figure 12 As shown, the nitrogen adsorption isotherm exhibits typical Type IV characteristics, indicating that the material has significant mesoporous features, accompanied by an H3-type hysteresis loop, suggesting that the sample's pore structure is mainly composed of slit pores or lamellar particle packing pores. The curves coincide in the low-pressure region, indicating good adsorption reversibility.
Claims
1. A method for large-scale fabrication of two-dimensional nanosheets based on external field coupling technology, characterized in that, The process includes the following steps: (1) dissolving polyvinylpyrrolidone (PVP) with a molecular weight of 1,300,000 in anhydrous ethanol and stirring at 190–210 rpm to form a homogeneous and transparent solution; the ratio of PVP to anhydrous ethanol is 0.6 g:3 mL; (2) adding acetone and a metal precursor salt to the solution from step (1) and continuing to stir to obtain a homogeneous and stable precursor solution; the metal precursor salt includes acetylacetone salt or tetraisopropyl titanate; the acetylacetone salt is cerium acetylacetone or iron acetylacetone; (3) performing air-jet spinning of the precursor solution through a 19–23 G needle, with an air-jet pressure of 2–7 bar, a solution flow rate of 5–80 mL / h, and a distance of 30 cm between the needle and the nonwoven fabric receiver to obtain composite nanosheets; (4) heating the composite nanosheets to 500–600 °C in an air atmosphere at 4.1–4.3 °C / min. Two-dimensional nanosheets of multi-level porous metal oxide were obtained by calcination at ℃.
2. The method according to claim 1, characterized in that, In step (2), the amount of acetone added is 3 mL and the amount of metal precursor salt added is 0.3 g.
3. The method according to claim 1, characterized in that, In step (3), the gas injection pressure is 7 bar and the solution flow rate is 20 mL / h.
4. The method according to claim 1, characterized in that, The needle mentioned in step (3) is 23 G.
5. The method according to claim 1, characterized in that, In step (3), the air-jet spinning environment temperature is 25 ℃ and the ambient humidity is less than 40%.
6. The method according to claim 1, characterized in that, In step (4), the calcination environment is an air atmosphere in a muffle furnace.
7. A two-dimensional nanosheet prepared by the method according to any one of claims 1-6, characterized in that, The two-dimensional nanosheets are CeO2 or Fe2O3 nanosheets.