Device and method for preparing black phosphorus nanosheet through sealed ice bath ultrasound

Abstract

The invention relates to the technical field of nanometer material preparation, in particular to a device and method for preparing black phosphorus nanosheets through sealed ice bath ultrasound, the device comprises two sealed reaction containers, the two reaction containers are the reaction container I and the reaction container II respectively, and ultrasonic probes are fixedly installed on the two opposite side walls of the reaction container I respectively; a liquid passing pipeline is connected between the two reaction containers, a nano-filtration membrane is arranged in the liquid passing pipeline, and materials in the reaction container I enter the reaction container II after being filtered by the nano-filtration membrane; the two reaction containers are respectively provided with a vacuum pump interface; the two reaction containers are arranged in a thermal insulation sleeve, and an ice-water mixture circularly flows in the thermal insulation sleeve; the oxidative degradation of the black phosphorus is avoided through the vacuum sealing environment of the reaction container, and the high quality of the black phosphorus nanosheet is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterial preparation, and particularly to a device and method for preparing black phosphorus nanosheets by sealed ice bath ultrasonic treatment. Background Art

[0002] Due to its unique two-dimensional layered structure and excellent physical and chemical properties, black phosphorus nanosheets have shown broad application prospects in multiple fields. To improve the stability and electrical conductivity of black phosphorus, composite with porous carbon materials is an effective solution at present. Porous carbon not only provides a high specific surface area and a good conductive network, but also can effectively alleviate the volume expansion problem of black phosphorus in energy storage applications.

[0003] Existing devices for preparing black phosphorus nanomaterials, such as the utility model patent with the application number CN201720705067.4, disclose a liquid-phase exfoliation device for preparing two-dimensional nanomaterials, including a solvent tank, a cutter head with emulsifying and cutting functions, and an ultrasonic probe. Both the cutter head and the ultrasonic probe are located in the solvent tank. The cutter head is located at a height of 1 / 4 - 1 / 2 from the bottom of the solvent tank, and the ultrasonic probe is located at a height of 1 / 4 - 3 / 4 from the bottom of the solvent tank.

[0004] Existing devices for preparing black phosphorus nanomaterials have the following defects: Due to the uneven distribution of ultrasonic waves of the ultrasonic probe in the existing devices for preparing black phosphorus nanomaterials, local sound field intensity differences are formed in the liquid. This non-uniformity makes the exfoliation process of black phosphorus powder unstable, resulting in inconsistent sizes and layer distributions of the prepared nanosheets, affecting the uniformity and quality of the materials; in addition, since a large amount of heat is generated when ultrasonic waves propagate in the liquid, the increase in the solution temperature accelerates the oxidation and decomposition of black phosphorus; in an open environment, black phosphorus nanosheets are directly exposed to oxygen and moisture in the air, and are extremely easy to oxidize and decompose, further reducing the yield and quality; during the preparation process using traditional methods, centrifugal separation of black phosphorus nanomaterials is required. The centrifugal separation time is long, and the sample is continuously in contact with air during the operation, and there is also an oxidation problem. Moreover, the centrifugal process is cumbersome and difficult to meet the requirements of high-efficiency large-scale preparation. Summary of the Invention

[0005] The purpose of the present invention is to provide a device and method for preparing black phosphorus nanosheets by sealed ice bath ultrasonic treatment, so as to improve the uniformity, quality and efficiency of black phosphorus nanosheet preparation, and solve the defects mentioned in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] An apparatus for preparing black phosphorus nanosheets by sealed ice bath ultrasound includes two sealed reaction vessels, namely reaction vessel I and reaction vessel II. Ultrasonic probes are fixedly installed on the opposite side walls of reaction vessel I respectively. A liquid connection pipe is connected between the two reaction vessels, and a nano filter membrane is provided in the liquid connection pipe. The materials in reaction vessel I enter reaction vessel II after being filtered by the nano filter membrane. Vacuum pump interfaces are provided on the two reaction vessels respectively. The two reaction vessels are placed in a heat preservation sleeve, and ice-water mixture circulates in the heat preservation sleeve.

[0008] As a further improvement, the reaction vessel is a quartz bottle, and a vacuum seal cover resistant to chemical corrosion is installed at the bottle mouth of the quartz bottle.

[0009] As a further improvement, the vacuum pump interface is arranged at the top of the reaction vessel, and the vacuum pump interface is made of stainless steel or aluminum alloy, and the outer surface of the vacuum pump interface is fluorinated.

[0010] As a further improvement, a flow regulating valve is provided on the vacuum pump interface.

[0011] As a further improvement, a liquid inlet is provided at the top of reaction vessel I; a liquid outlet is provided at one side of the bottom of the reaction vessel.

[0012] As a further improvement, the nano filter membrane is a polyvinylidene fluoride membrane.

[0013] As a further improvement, multiple layers of nano filter membranes are provided, and the multiple layers of nano filter membranes are arranged along the flowing direction of the materials in the liquid connection pipe, and the pore diameters of the multiple layers of nano filter membranes gradually decrease along the flowing direction of the materials in the liquid connection pipe.

[0014] A method for preparing black phosphorus nanosheets by sealed ice bath ultrasound uses the apparatus for preparing black phosphorus nanosheets by sealed ice bath ultrasound as described above, and this method includes the following steps:

[0015] S1, Black phosphorus bulk crystals are ground in a vacuum glove box for 5 minutes to obtain 10 - 30 mg of black phosphorus powder. The black phosphorus powder is mixed with 50 - 100 mL of dimethyl sulfoxamide and injected into reaction vessel I.

[0016] S2, Reaction vessel I and reaction vessel II are respectively connected to a vacuum pump through the vacuum pump interfaces. The two vacuum pumps are used to evacuate reaction vessel I and reaction vessel II to -0.08 MPa and -0.1 MPa respectively. At the same time, an ice-water mixture is circulated into the heat preservation sleeve through an ice-water circulation system, and the reaction vessels are placed in the ice-water mixture in the heat preservation sleeve, and the temperature of the ice-water mixture is maintained at 0 - 4 °C.

[0017] S3. Adjust the parameters of the ultrasonic probe to 100 - 300 W, and perform ultrasonic treatment for 8 - 16 hours. Both of the two ultrasonic probes 2 are in working state to prepare few - layer black phosphorus nanosheets. After the ultrasonic treatment, the few - layer black phosphorus nanosheets are transferred from the reaction vessel I to the reaction vessel II through the nano - filtration membrane.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] (1) Anti - oxidation design: The vacuum - sealed environment of the reaction vessel avoids the oxidative degradation of black phosphorus, ensuring the high quality of black phosphorus nanosheets.

[0020] (2) Good cooling effect: Using an ice - water mixture for ice - bath cooling prevents the damage to the black phosphorus structure caused by the thermal effect during the ultrasonic process.

[0021] (3) Uniform size: Through the design of upper and lower double ultrasonic probes, the size and distribution of few - layer black phosphorus nanosheets can be controlled more precisely, improving the consistency of the product.

[0022] (4) Efficient separation: Using the nano - filtration membrane to directly separate few - layer black phosphorus nanosheets, eliminating the centrifugation step in the traditional method and improving the preparation efficiency.

[0023] (5) Simplified operation: The whole process is carried out in a sealed environment, with simple operation and high automation degree, suitable for large - scale production. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 It is a schematic structural diagram of an embodiment of the present invention.

[0026] In the figure: 1 - reaction vessel; 101 - reaction vessel I; 102 - reaction vessel II; 2 - ultrasonic probe; 3 - liquid - passing pipeline; 4 - nano - filtration membrane; 5 - vacuum pump interface; 6 - heat - insulating sleeve; 7 - ice - water mixture; 8 - liquid inlet; 9 - liquid outlet; 10 - few - layer black phosphorus nanosheets; 11 - black phosphorus powder. Detailed Embodiments

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] As Figure 1 shown, a device for preparing black phosphorus nanosheets by sealed ice bath ultrasound includes two sealed reaction vessels 1. The reaction vessel 1 is a quartz bottle, which is made of high-purity quartz glass, has excellent chemical inertness and high temperature resistance, can withstand strong vibrations and heat generation during ultrasound, and does not react with black phosphorus or the solution at the same time; a chemically corrosion-resistant vacuum seal cover is installed at the mouth of the quartz bottle, and a good seal is achieved between the vacuum seal cover and the quartz bottle through a silicone rubber gasket and a locking device to prevent air from entering the quartz bottle.

[0029] The two reaction vessels 1 are respectively the reaction vessel I 101 on the left and the reaction vessel II 102 on the right. Ultrasonic probes 2 are respectively fixedly installed on the top wall and the bottom wall of the reaction vessel I 101. The ultrasonic probe 2 extends into the reaction vessel I 101 and contacts the liquid in the reaction vessel I 101. Through the bidirectional ultrasonic action, the uniformity of the sound field distribution is enhanced, ensuring the stability of the black phosphorus powder peeling process and preparing few-layer black phosphorus nanosheets with consistent size and number of layers.

[0030] A liquid connection pipe 3 is connected between the two reaction vessels 1. There are through ports on the right side of the reaction vessel I and the left side of the reaction vessel II respectively. The two through ports are hermetically docked to form the liquid connection pipe 3. A replaceable nano filter membrane 4 is provided in the liquid connection pipe 3. The materials in the reaction vessel I enter the reaction vessel II after being filtered by the nano filter membrane 4. The nano filter membrane 4 separates the reaction vessel I 101 and the reaction vessel II 102 from left to right, and is used to directly separate and collect unpeeled black phosphorus particles or coarser few-layer black phosphorus nanosheets in a vacuum environment, avoiding the oxidation problem caused by traditional centrifugation operations. In this embodiment, the nano filter membrane 4 is a polyvinylidene fluoride membrane, which has high compressive resistance to prevent damage caused by external pressure during vacuum pumping. The nano filter membrane 4 is embedded in a detachable frame, which is convenient for replacement and cleaning. The frame is fixed in the liquid connection pipe 3 by a sealing gasket and a lock to avoid leakage during the filtration process. A multi-layer nano filter membrane 4 structure can be adopted to improve the separation efficiency. Specifically, the multi-layer nano filter membrane 4 is arranged along the flowing direction of the materials in the liquid connection pipe 3, and the pore diameters of the multi-layer nano filter membrane 4 gradually decrease from left to right along the flowing direction of the materials in the liquid connection pipe 3: the nano filter membrane 4 with a larger pore diameter on the left is used for rough filtration of unpeeled black phosphorus particles; the nano filter membrane 4 with a smaller pore diameter on the right is used to capture coarser few-layer black phosphorus nanosheets and further purify them.

[0031] Vacuum pump interfaces 5 are respectively provided on two reaction vessels 1. Independent vacuum pumps are connected to the two reaction vessels 1 through the vacuum pump interfaces 5. The vacuum pumps evacuate the reaction vessels 1 to prevent the black phosphorus nanomaterials from being oxidized and decomposed due to exposure to air during the preparation process. By adjusting the flow rates of the two vacuum pumps, the pressure difference between reaction vessel I 101 and reaction vessel II 102 can be precisely controlled. Through the small pressure difference between reaction vessel I 101 and reaction vessel II 102, few-layer black phosphorus nanosheets that meet the conditions are transferred from reaction vessel I 101 to reaction vessel II 102 through the nano filtration membrane 4.

[0032] The two reaction vessels 1 are placed in a heat preservation sleeve 6. The heat preservation sleeve 6 is connected to an ice-water circulation system. Ice-water mixture 7 is circulated and injected into the heat preservation sleeve 6 through the ice-water circulation system to efficiently reduce the temperature of the solution in the reaction vessels 1 during the ultrasonic process and avoid the influence of temperature rise on the quality of the black phosphorus nanomaterials. The ice-water circulation system is equipped with a temperature sensor and a regulating valve to achieve precise temperature control.

[0033] The vacuum pump interface 5 is arranged at the top of the reaction vessel 1. The vacuum pump interface 5 is made of stainless steel or aluminum alloy. The outer surface of the vacuum pump interface 5 is fluorinated. High-quality fluororubber sealing gaskets are used. The diameter of the vacuum pump interface 5 can be designed to be 6 mm - 10 mm.

[0034] A flow regulating valve is provided on the vacuum pump interface 5. Through the flow regulating valve, the vacuum degree in each reaction vessel 1 can be finely adjusted to ensure that the filtration process of few-layer black phosphorus nanosheets does not occur too fast or too slow, so as to avoid the accumulation or uneven distribution of black phosphorus particles or coarser few-layer black phosphorus nanosheets on the nano filtration membrane 4.

[0035] An inlet 8 is provided at the top of reaction vessel I 101; outlet ports 9 are respectively provided on the bottom sides of reaction vessel I 101 and reaction vessel II 102. Manual regulating valves are respectively installed on the inlet 8 and the outlet ports 9.

[0036] A method for preparing black phosphorus nanosheets by sealed ice bath ultrasonic treatment, applying a device for preparing black phosphorus nanosheets by sealed ice bath ultrasonic treatment, the method comprising the following steps:

[0037] S1, black phosphorus bulk crystals are ground in a vacuum glove box for 5 minutes to obtain 10 - 30 mg of black phosphorus powder 11. The black phosphorus powder 11 is mixed with a solvent. The solvent is 50 - 100 mL of dimethyl sulfoximide and is injected into reaction vessel I 101; the solvent can also be carbon tetrachloride, dimethyl sulfoximide, N,N-dimethylformamide, acetone, etc.;

[0038] S2. The reaction vessel I 101 and the reaction vessel II 102 are each connected to a vacuum pump through a vacuum pump interface 5, and the reaction vessel I 101 and the reaction vessel II 102 are evacuated to -0.08 MPa and -0.1 MPa respectively through the two vacuum pumps. At the same time, an ice-water mixture 7 is circulated and injected into the heat preservation jacket 6 through an ice-water circulation system. The reaction vessel 1 is placed in the ice-water mixture 7 of the heat preservation jacket 6. The ice-water mixture 7 needs to submerge at least half of the volume of the reaction vessel 1, and the temperature of the ice-water mixture 7 is maintained at 0 - 4 °C.

[0039] S3. Adjust the parameters of the ultrasonic probe to 100 - 300 W, and ultrasonicate for 8 - 16 hours. Both ultrasonic probes 2 are in working state to prepare few-layer black phosphorus nanosheets 10. After the ultrasonication, the qualified few-layer black phosphorus nanosheets 10 are transferred from the reaction vessel I 101 to the reaction vessel II 102 through the nanofilter membrane 4. After the preparation is completed, remove the heat preservation jacket 6, dry the water on the reaction vessel 1, gently rotate and open the manual regulating valve on the reaction vessel II 102, and the few-layer black phosphorus nanosheets 10 mixture flows out from the liquid outlet 9 of the reaction vessel II 102 and can be collected with a glass bottle.

[0040] Example 1

[0041] Effect of the ratio of black phosphorus powder to solvent on the quality of few-layer black phosphorus nanosheets, steps:

[0042] (1) Grind 20 mg of black phosphorus bulk crystal in a glove box for 5 minutes to obtain uniform black phosphorus powder.

[0043] (2) Ratio of solvent to black phosphorus powder:

[0044] Experiment A: 20 mg of black phosphorus, 50 mL of dimethyl sulfoxamide

[0045] Experiment B: 20 mg of black phosphorus, 75 mL of dimethyl sulfoxamide

[0046] Experiment C: 20 mg of black phosphorus, 100 mL of dimethyl sulfoxamide

[0047] (3) Ultrasonic power: 200 W, ultrasonic time: 12 hours, ultrasonic frequency: 40 kHz. Ice-water bath: All experiments are carried out in an ice-water mixture at 0 °C to 4 °C to ensure the constant temperature of the solution and prevent overheating from damaging the black phosphorus structure.

[0048] (4) Operation: Inject the dissolved black phosphorus solution into the reaction vessel Ⅰ101, and ensure that the liquid inlet 8 and the liquid outlet 9 of the left and right reaction vessels 1 are closed to prevent the solution from overflowing during the ultrasonic process. Use a vacuum pump to evacuate the reaction vessel Ⅰ101 and the reaction vessel Ⅱ102 to -0.08MPa and -0.1MPa respectively, and maintain the vacuum environment throughout the process to reduce the generation of bubbles in the solution and improve the ultrasonic effect. After the ultrasonic treatment is completed, filter through the nanofiltration membrane 4 to collect the obtained black phosphorus nanosheets.

[0049] Result analysis:

[0050] Experiment A (20 mg: 50 mL): The number of black phosphorus nanosheets is about 10-12 layers, the dispersion is poor, and there are many agglomerations. This may be due to insufficient solvent, which makes it difficult to completely disperse black phosphorus.

[0051] Experiment B (20 mg: 75 mL): The number of black phosphorus nanosheets is about 8-10 layers, with good dispersion and high stability. Under this condition, black phosphorus is ideally dispersed with a moderate number of layers.

[0052] Experiment C (20 mg: 100 mL): The number of black phosphorus nanosheets is 8-10, and the dispersibility and stability are optimal. Increasing the amount of solvent further improves the dispersion effect, and the obtained black phosphorus nanosheets are thin and uniform.

[0053] in conclusion:

[0054] Increasing the amount of solvent (e.g., 100 mL DMSO) can effectively improve the dispersibility of black phosphorus nanosheets, reduce agglomeration, and obtain thinner few-layer black phosphorus nanosheets. 50 mL of solvent is too small, which may lead to insufficient solvent and poor dispersion effect.

[0055] Example 2

[0056] Orthogonal experiment was used to optimize the effect of ultrasonic power and time on the quality of black phosphorus nanosheets. Steps:

[0057] (1) Take the black phosphorus block crystals and grind them in a glove box for 5 minutes to obtain 20 mg of uniform black phosphorus powder.

[0058] (2) Ratio of solvent to black phosphorus powder: 20 mg black phosphorus, 100 mL dimethylsulfamide.

[0059] (3) Ultrasonic power: 200 W, 250 W, 300 W, ultrasonic time: 8 h, 12 h, 16 h. Ice-water bath: All experiments were conducted in an ice-water mixture at 0°C to 4°C to ensure a stable reaction environment.

[0060] (4) Operation: Inject the dissolved black phosphorus solution into reaction vessel I 101, ensuring that the solution does not overflow. Use a vacuum pump to evacuate reaction vessel I 101 and reaction vessel II 102 to -0.08 MPa and -0.1 MPa respectively, maintaining a vacuum environment throughout the ultrasonic process to remove bubbles and improve the ultrasonic effect. After the ultrasonic treatment is completed, filter through the nanofilter membrane 4 to collect few-layer black phosphorus nanosheets.

[0061] (5) Orthogonal experimental design: Select ultrasonic power and ultrasonic time as the main experimental factors.

[0062]

[0063]

[0064] (6) Experimental results

[0065]

[0066] (7) Data analysis

[0067] Based on the above results, analysis of variance (ANOVA) was performed to evaluate the influence degree of each factor (ultrasonic power and ultrasonic time) on response indexes such as the number of layers, dispersibility, and stability of black phosphorus nanosheets. Through the analysis, the following conclusions were drawn: 1) Influence of ultrasonic power: Ultrasonic power has a significant influence on the number of layers and dispersibility of black phosphorus nanosheets. As the ultrasonic power increases, the number of layers of black phosphorus nanosheets gradually decreases, the dispersibility improves, and the particle size tends to decrease. At a power of 300 W, the number of layers is the least and the dispersibility is the best. 2) Influence of ultrasonic time: Prolonging the ultrasonic time helps to further exfoliate the black phosphorus layers, but an overly long ultrasonic time (such as 16 hours) may not significantly improve the dispersibility. 3) For most experimental groups, an ultrasonic time of 12 hours provides relatively ideal results. However, it should be noted that increasing the ultrasonic time is also beneficial to improving the stability. Especially under high power (300 W) conditions, a longer ultrasonic time can significantly improve the stability of the nanosheets. 4) Interaction: The interaction between ultrasonic power and time significantly affects the quality of the final black phosphorus nanosheets. Specifically, at a power of 300 W, an ultrasonic time of 16 hours can obtain thinner and more uniform black phosphorus nanosheets, and at the same time, the dispersibility and stability are also the best. Under lower power (200 W) conditions, prolonging the ultrasonic time has limited effect on improving the dispersibility and stability, and the reduction amplitude of the number of layers is smaller.

[0068] The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A sealed ice bath ultrasonic preparation device for black phosphorus nanosheets, characterized in that: The invention comprises two sealed reaction containers (1), the two reaction containers are reaction container I (101) and reaction container II (102), and ultrasonic probes (2) are fixedly mounted on opposite side walls of the reaction container I (101); a liquid passage (3) is connected between the two reaction containers (1), a nanofiltration membrane (4) is arranged in the liquid passage (3), and the material in the reaction container I (101) enters the reaction container II (102) after being filtered by the nanofiltration membrane (4); vacuum pump interfaces (5) are respectively arranged on the two reaction containers (1); the two reaction containers (1) are placed in a heat preservation jacket (6), and an ice-water mixture (7) circulates in the heat preservation jacket (6).

2. The device for preparing black phosphorus nanosheets by sealed ice bath ultrasound according to claim 1, characterized in that: The reaction container (1) is a quartz bottle, and a chemically corrosion-resistant vacuum sealing cover is installed at the bottle mouth of the quartz bottle.

3. The device for preparing black phosphorus nanosheets by sealed ice bath ultrasound according to claim 1, characterized in that: The vacuum pump interface (5) is arranged on the top of the reaction container (1); the vacuum pump interface (5) is made of stainless steel or aluminum alloy; and the outer surface of the vacuum pump interface (5) is fluorinated.

4. The device for preparing black phosphorus nanosheets by sealed ice bath ultrasound according to claim 1, characterized in that: The vacuum pump interface (5) is provided with a flow regulating valve.

5. The device for preparing black phosphorus nanosheets by sealed ice bath ultrasound according to claim 1, characterized in that: The top of the reaction container I (101) is provided with a liquid inlet (8); and one side of the bottom of the reaction container (1) is provided with a liquid outlet (9).

6. The device for preparing black phosphorus nanosheets by sealed ice bath ultrasound according to claim 1, characterized in that: The nanofiltration membrane (4) is a polyvinylidene fluoride membrane.

7. The device for preparing black phosphorus nanosheets by sealed ice bath ultrasound according to claim 1, characterized in that: The nanofiltration membrane (4) is provided with multiple layers, the multiple layers of the nanofiltration membrane (4) are arranged along the material flow direction in the liquid passage pipe (3), and the pore size of the multiple layers of the nanofiltration membrane (4) gradually decreases along the material flow direction in the liquid passage pipe (3).

8. A method for preparing black phosphorus nanosheets by sealed ice bath ultrasound, using the device for preparing black phosphorus nanosheets by sealed ice bath ultrasound according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: S1, black phosphorus block crystals are ground in a vacuum glove box for 5 minutes to obtain 10-30 mg of black phosphorus powder (11), the black phosphorus powder (11) is mixed with 50-100 mL of dimethylsulfamide, and injected into the reaction vessel I (101); S2, the reaction container I (101) and the reaction container II (102) are each connected to a vacuum pump via a vacuum pump interface (5), and the reaction container I (101) and the reaction container II (102) are evacuated to -0.08MPa and -0.1MPa respectively via the two vacuum pumps; at the same time, an ice-water mixture (7) is circulated and injected into the insulation jacket (6) via an ice-water circulation system, and the reaction container (1) is placed in the ice-water mixture (7) in the insulation jacket (6), and the temperature of the ice-water mixture (7) is maintained at 0-4°C; S3, adjusting the parameters of the ultrasonic probe (2) to 100-300W, ultrasonicating for 8-16 hours, with both the ultrasonic probes (2) 2 in a working state, to obtain a few-layer black phosphorus nanosheet (10); after the ultrasonication is completed, the few-layer black phosphorus nanosheet (10) is transferred from the reaction container I (101) to the reaction container II (102) through the nanofiltration membrane (4).

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