阅读说明：本技术 一种二维纳米片的制备方法 (Preparation method of two-dimensional nanosheet ) 是由 顾林 孙九龙 于 2021-08-10 设计创作，主要内容包括：本发明公开了一种二维纳米片的制备方法,涉及纳米材料技术领域。本发明所述二维纳米片的制备方法包括如下步骤：(1)在惰性气体中煅烧二维纳米材料,煅烧条件为：850～900℃,1.5～2.5h；(2)取煅烧后的二维纳米材料进行等离子溅射处理得到羟基化的二维纳米材料；(3)将羟基化的二维纳米材料加入溶剂中,然后以细胞超声粉碎仪进行处理；(4)取上清液进行抽滤,干燥,得到所述二维纳米片。本发明所述二维纳米片的制备方法简单高效,并且制备的纳米片的结构不会受到破坏。(The invention discloses a preparation method of a two-dimensional nanosheet, and relates to the technical field of nanomaterials. The preparation method of the two-dimensional nanosheet comprises the following steps: (1) calcining the two-dimensional nano material in inert gas under the calcining conditions that: 850-900 ℃ for 1.5-2.5 h; (2) carrying out plasma sputtering treatment on the calcined two-dimensional nano material to obtain a hydroxylated two-dimensional nano material; (3) adding the hydroxylated two-dimensional nano material into a solvent, and then processing by using a cell ultrasonic crusher; (4) and (3) taking the supernatant, carrying out suction filtration and drying to obtain the two-dimensional nanosheet. The preparation method of the two-dimensional nanosheet is simple and efficient, and the structure of the prepared nanosheet cannot be damaged.)

1. A preparation method of a two-dimensional nanosheet is characterized by comprising the following steps:

(1) calcining the two-dimensional material in an inert gas under the following calcining conditions: 850-900 ℃ for 1.5-2.5 h;

(2) carrying out plasma sputtering treatment on the calcined two-dimensional material to obtain a hydroxylated two-dimensional material;

(3) adding the hydroxylated two-dimensional material into a solvent, and then processing by using a cell ultrasonic crusher;

(4) centrifuging, taking supernatant, performing suction filtration, and drying to obtain the two-dimensional nanosheet.

2. A method of producing two-dimensional nanoplatelets according to claim 1 wherein in step (1), the inert gas has a gas flow rate of 80 to 150 seem.

3. A method of making two-dimensional nanoplatelets according to claim 1 wherein in step (2) air plasma sputtering is used for at least 30 min.

4. A method of making two-dimensional nanoplatelets according to claim 1 wherein in step (3) the solvent comprises at least one of N, N-dimethylformamide, N-methylpyrrolidone, isopropanol, ethanol, water.

5. A method of making two-dimensional nanoplatelets according to claim 4 wherein in step (3) the solvent is N, N-dimethylformamide.

6. A method of preparing two-dimensional nanoplatelets according to claim 1 wherein in step (3) the ratio of the mass of hydroxylated two-dimensional material to the volume of solvent is: 1-3 mg/mL.

7. A method of preparing two-dimensional nanoplatelets according to claim 1 wherein in step (3) the ratio of ultrasound time to gap time is: 1: 1-1.5, and the total working time is 7-9 h.

8. A method of preparing two-dimensional nanoplatelets according to claim 1 wherein in step (4) the centrifugation is carried out for 8-15 min at a rotation speed of 1300-1700 rpm.

9. A method of making two-dimensional nanoplatelets according to claim 1 wherein in step (4) drying is performed in a vacuum oven.

Technical Field

The invention relates to the technical field of nano materials, in particular to a preparation method of a two-dimensional nanosheet.

Background

In the past decades, two-dimensional nanomaterials have attracted extensive attention due to excellent properties of light, electricity, magnetism, heat and the like, and a plurality of documents report that the two-dimensional nanomaterials have huge application potentials in the fields of catalysis, energy storage, heat conduction, metal corrosion protection and the like at home and abroad at present. Graphene (G), boron nitride (h-B)N), Black Phosphorus (BP), molybdenum disulfide (MoS)₂) Many two-dimensional nanomaterials such as boron and the like can be peeled into ultrathin two-dimensional nano sheet structures from a layered stacked structure, and the physical properties of the two-dimensional nanomaterials can be greatly changed in the peeling process. In order to give full play to the excellent characteristics of two-dimensional nanomaterials, develop electronic devices based on single-layer or thin-layer two-dimensional nanomaterials, construct three-dimensional macroscopic materials with new structures and new functions by using the two-dimensional nanomaterials, expand and expand the application fields of the two-dimensional nanomaterials, the most fundamental problem is to solve the large-scale controllable preparation of the two-dimensional nanomaterials.

Since single-layer graphene was manufactured in 2004 by the tape-and-tear method, many researchers developed many methods for producing two-dimensional nanoplatelets: such as ion exchange stripping, redox, shear stripping, hydrothermal stripping, and the like. Although the methods can strip two-dimensional materials, the methods cannot be general methods for stripping two-dimensional nano materials due to low stripping yield and complex preparation process.

Ion exchange stripping methods are directed only to those layered materials that have an ion exchange between layers; the redox method has the advantage of preparing graphene on a large scale, but the obtained graphene often has larger structural defects and is difficult to meet the application in the field of electronic devices with very strict structural requirements; the shear stripping method is easy to operate, but the efficiency of the single-chip layer in the two-dimensional nano material obtained by stripping is low, and the strong shear force can cause great damage to the structure of the nano sheet; although the hydrothermal stripping method can effectively strip the two-dimensional nanomaterial, it requires operation in a high-pressure environment, and is not suitable for industrial mass production.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a simple and efficient preparation method of a two-dimensional nanosheet, and the structure of the nanosheet prepared by the method cannot be damaged.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a preparation method of two-dimensional nanosheets comprises the following steps:

(1) calcining the two-dimensional material in an inert gas under the following calcining conditions: 850-900 ℃ for 1.5-2.5 h;

(2) carrying out plasma sputtering treatment on the calcined two-dimensional material to obtain a hydroxylated two-dimensional material;

(3) adding the hydroxylated two-dimensional material into a solvent, and then processing by using a cell ultrasonic crusher;

(4) centrifuging, taking supernatant, performing suction filtration, and drying to obtain the two-dimensional nanosheet.

According to the invention, through calcining the two-dimensional nano material, the van der Waals force between two-dimensional nano material sheets can be reduced, and the flaky crystal structure of the two-dimensional nano material cannot be damaged. Hydroxyl can be introduced on the surface of the two-dimensional nano material through air plasma sputtering, and the compatibility of the two-dimensional nano material in a solvent is greatly enhanced. And finally, carrying out ultrasonic stripping by using a cell ultrasonic crusher, and quickly obtaining the two-dimensional nanosheet with an integral structure.

Preferably, in the step (1), the flow rate of the inert gas is 80 to 150 sccm. The air flow can influence the temperature, and too high air flow can take away more heat, reduces the sintering effect.

Preferably, in the step (2), the sputtering is performed by air plasma for at least 30 min. The sputtering time is controlled to be at least 30min, so that enough hydroxyl groups can be obtained on the surface of the two-dimensional nano material, and the dispersibility of the two-dimensional nano material in a solvent is improved.

Preferably, in the step (3), the solvent comprises at least one of N, N-dimethylformamide, N-methylpyrrolidone, isopropanol, ethanol and water.

Further preferably, in the step (3), the solvent is N, N-dimethylformamide. The applicant of the invention proves through experiments that when the solvent is N, N-dimethylformamide, the yield of the two-dimensional nanosheet can reach 80%.

Preferably, in the step (3), the ratio of the mass of the hydroxylated two-dimensional nanomaterial to the volume of the solvent is: 3-6 mg/mL. The ratio of the two is controlled to be 1-3 mg/mL, so that higher yield can be obtained under the condition of no solvent waste, and the cost is controlled.

Preferably, in the step (3), the ratio of the ultrasonic time to the gap time is: 1: 1-1.5, and the total working time is 7-9 h. When the ratio of the ultrasonic time to the gap time is 1: 1-1.5, the stripping efficiency is highest.

Preferably, in the step (4), the centrifugation is carried out for 8-15 min at the rotating speed of 1300-1700 rpm. Too low a centrifugation rate can cause the supernatant to contain part of the two-dimensional materials which are not stripped, and too high a centrifugation rate can cause part of the two-dimensional nanosheets to be separated, so that the yield of the two-dimensional nanosheets is reduced.

Preferably, in the step (4), drying is performed in a vacuum drying oven. The two-dimensional nanosheets can be ensured not to be oxidized by drying in a vacuum environment.

Compared with the prior art, the invention has the beneficial effects that: according to the invention, the two-dimensional nano material is sintered at 850-900 ℃ to reduce the van der Waals force between nano sheets, then hydroxyl is introduced on the surface of the two-dimensional nano material through air plasma sputtering to increase the compatibility of the two-dimensional nano material in a solvent, and finally the two-dimensional nano material is stripped by using a cell ultrasonic crusher, so that the yield higher than 80% is obtained.

Drawings

FIG. 1 is an AFM image of nanoplatelets prepared by the method described in example 1;

FIG. 2 is an AFM image of nanoplatelets prepared by the method described in example 2;

FIG. 3 is a graph of the boron nitride morphology of example 1; a) SEM image of boron nitride powder; b) SEM images of boron nitride after stripping in isopropanol; c) SEM images of boron nitride after stripping in N, N-dimethylformamide; d) SEM images of boron nitride after stripping in N-methylpyrrolidone.

Detailed Description

To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to the accompanying drawings and specific embodiments.

Example 1

In an embodiment of the method for preparing a two-dimensional nanosheet, the method of this embodiment includes the following steps:

(1) putting boron nitride powder into a quartz boat, then putting the quartz boat into a tube furnace, calcining the quartz boat for 2 hours at 900 ℃, and introducing 100sccm argon gas in the calcining process;

(2) sputtering the calcined two-dimensional material in a plasma cleaner for 30min by using air plasma to obtain a hydroxylated two-dimensional material;

(3) 200mg of hydroxylated two-dimensional material was weighed into 40mL of N, N-Dimethylformamide (DMF), N-methylpyrrolidone (NMP), Isopropanol (IPA), and ethanol (C)₂H₅OH), deionized water (H)₂O), putting the dispersion into a cell ultrasonic crusher, and working for 8 hours under the conditions that the gap time is 3s and the ultrasonic time is 2 s;

(4) centrifuging for 10min in a centrifuge at the rotating speed of 1500rpm, taking supernate, performing suction filtration (the aperture of a microporous filter membrane is 0.22 mu m), and drying to obtain the two-dimensional nanosheet.

A small amount of two-dimensional nanosheets are dispersed in DMF for atomic force microscopy test, and fig. 1 is a test chart, so that the thickness of the stripped nanosheets is about 5nm, and effective stripping of boron nitride is successfully realized. The yields of boron nitride nanoplates in different solvents are shown in table 1.

TABLE 1

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	80.1％	71.45％	70.1％	60.5％	32.3％

Example 2

In an embodiment of the method for preparing a two-dimensional nanosheet, the method for preparing a two-dimensional nanosheet described in this embodiment is different from embodiment 1 only in that the two-dimensional material selected in the present invention is graphite powder. FIG. 2 is an AFM image of the exfoliated nanoplatelets, from which it can be seen that the thickness of the nanoplatelets is about 4nm, indicating that the present invention achieves effective exfoliation of graphene. The yields of graphene in different solvents are shown in table 2.

TABLE 2

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	46％	37.4％	21.6％	7.8％	4.0％

Example 3

In an embodiment of the preparation method of the two-dimensional nanosheet, the preparation method of the two-dimensional nanosheet is different from that in embodiment 1 only in that the two-dimensional material selected in the present invention is tungsten disulfide powder. The thickness of the prepared nanosheet was tested to be 5 nm. The yields of tungsten disulfide nanoplates in different solvents are shown in table 3.

TABLE 3

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	60.3％	57.7％	50.3％	23.8％	17.9％

Example 4

In an embodiment of the preparation method of the two-dimensional nanosheet, the preparation method of the two-dimensional nanosheet is different from that in embodiment 1 only in that the two-dimensional material selected in the present invention is molybdenum disulfide powder. The thickness of the prepared nanosheet was tested to be 6 nm. The yields of molybdenum disulfide nanoplates in different solvents are shown in table 4.

TABLE 4

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	72.3％	68.9％	60.5％	30.5％	20.1％

Example 5

In an embodiment of the method for preparing a two-dimensional nanosheet, the method for preparing a two-dimensional nanosheet described in this embodiment is different from embodiment 1 only in that the two-dimensional material selected in the present invention is boron powder. The thickness of the prepared nano-sheet is 3nm through testing. The yields of boron nanoplatelets in different solvents are shown in table 5.

TABLE 5

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	60.3％	57.2％	49.6％	29.3％	18.7％

Example 6

In an embodiment of the method for preparing two-dimensional nanoplates of the present invention, the method for preparing two-dimensional nanoplates of the present embodiment is different from embodiment 1 only in that the calcination temperature is 850 ℃. The thickness of the prepared nanosheet was tested to be 6 nm. The yields of nanoplatelets in different solvents are shown in table 6.

TABLE 6

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	80.0％	70.5％	71.5％	62.5％	35.3％

Example 7

In an embodiment of the method for preparing two-dimensional nanoplates according to the present invention, the method for preparing two-dimensional nanoplates in this embodiment is different from embodiment 1 only in that the calcination temperature is 880 ℃. The thickness of the prepared nanosheet was tested to be 5 nm. The yields of nanoplatelets in different solvents are shown in table 7.

TABLE 7

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	82％	72.3％	72.1％	63.4％	34.5％

Example 8

In an embodiment of the method for preparing two-dimensional nanoplates according to the present invention, the method for preparing two-dimensional nanoplates described in this embodiment is different from embodiment 1 only in that the gap time is 2 s. The thickness of the prepared nanosheet was tested to be 5 nm. The yields of nanoplatelets in different solvents are shown in table 8.

TABLE 8

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	80.0％	71.1％	70.5％	60.2％	32.8％

Example 9

In an embodiment of the method for preparing two-dimensional nanoplates according to the present invention, the method for preparing two-dimensional nanoplates described in this embodiment is different from embodiment 1 only in that the gap time is 4 s. The thickness of the prepared nanosheet was tested to be 6 nm. The yields of nanoplatelets in different solvents are shown in table 9.

TABLE 9

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	70％	60.1％	58.4％	48.6％	20.3％

Example 10

In an embodiment of the method for preparing two-dimensional nanoplates according to the present invention, the method for preparing two-dimensional nanoplates described in this embodiment is different from embodiment 1 only in that the gap time is 1 s. The thickness of the prepared nanosheet was tested to be 5 nm. The yields of nanoplatelets in different solvents are shown in table 10.

Watch 10

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	71％	61.1％	60.0％	50.1％	22.0％

Example 11

In an embodiment of the method for preparing two-dimensional nanoplatelets of the present invention, the method for preparing two-dimensional nanoplatelets of the present embodiment is different from embodiment 1 only in that the centrifugation rate is 1300 rpm. The thickness of the prepared nanosheet was tested to be 7 nm. The yields of nanoplatelets in different solvents are shown in table 11.

TABLE 11

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	83％	74％	72％	64％	35％

Example 12

In an embodiment of the method for preparing two-dimensional nanoplates of the present invention, the method for preparing two-dimensional nanoplates of the present embodiment differs from embodiment 1 only in that the centrifugation rate is 1700 rpm. The thickness of the prepared nano-sheet is 4nm through testing. The yields of nanoplatelets in different solvents are shown in table 12.

TABLE 12

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	79.9％	71.4％	69.6％	59.4％	32.4％

Example 13

In an embodiment of the method for preparing two-dimensional nanoplatelets of the present invention, the method for preparing two-dimensional nanoplatelets of the present embodiment is different from embodiment 1 only in that the centrifugation rate is 2000 rpm. The thickness of the prepared nano-sheet is 4nm through testing. The yields of nanoplatelets in different solvents are shown in table 13.

Watch 13

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	75％	65.1％	64％	55％	28.3％

Comparative example 1

A method for preparing two-dimensional nano-sheets, which is different from the method in example 1 only in that the calcination temperature is 930 ℃. The thickness of the prepared nanosheet was tested to be 5 nm. The yields of nanoplatelets in different solvents are shown in table 14.

TABLE 14

Solvent(s)	DMF	NMP	IPA	C2H5OH	H2O
						Yield of	65％	54.1％	54.2％	44.5％	22.3％

FIG. 3 is an SEM photograph of boron nitride in example 1, a) is an SEM photograph of a boron nitride powder; b) is SEM image of boron nitride stripped in isopropanol; c) is SEM image of boron nitride stripped in N, N-dimethyl formamide; d) is SEM picture of boron nitride stripped in N-methyl pyrrolidone; as can be seen from the figure, the structure of the nano-sheet after stripping is not destroyed, and the intact morphology is still maintained.

As can be seen from the test results in tables 1-14, the yield of nanosheets exfoliated in DMF was higher than that of other solvents. Comparing the yields of examples 1, 6 to 13 and comparative example 1, it can be seen that the calcination temperature has a great influence on the peeling yield of the nanosheets, and when the calcination temperature exceeds the range defined by the present invention, the yield is sharply reduced. In addition, the test data of comparative examples 1 and 8 to 10 show that the ratio of the ultrasonic time to the gap time has a large influence on the yield, and the yield is reduced when the ultrasonic time is too long or too short. As is clear from the results of the exfoliation in comparative examples 1 and 11 to 13, the centrifugation rate was too high, and a part of the exfoliated product was separated, which may lower the actual yield.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.