WO2022193571A1

WO2022193571A1 - Two-dimensional material and preparation method therefor and application thereof

Info

Publication number: WO2022193571A1
Application number: PCT/CN2021/116970
Authority: WO
Inventors: 成会明; 丘陵; 刘闽苏; 范维仁
Original assignee: 佛山市晟鹏科技有限公司
Priority date: 2021-03-15
Filing date: 2021-09-07
Publication date: 2022-09-22
Also published as: CN112978688A; CN112978688B

Abstract

Disclosed in the present invention are a two-dimensional material and a preparation method therefor and an application thereof. The first aspect of the present application provides the preparation method for the two-dimensional material, comprising the following steps: mixing a layered material with a strongly alkaline solution, applying mechanical force, and stripping off to obtain the two-dimensional material. The strongly alkaline solution is used as an aid for mechanically stripping off the two-dimensional material, so that the stripping effect of the shearing action of the mechanical force on the layered material is improved. Compared with a pure mechanical stripping method or an existing mechanochemical method, the synergistic action of a strongly alkaline additive and a wet process is more obvious, the direct contact between the mechanical force and the layered material is effectively reduced, sheet layers of the layered material are protected, damage caused by overlarge impact force is avoided, and thus the size of the sheet layers of the two-dimensional material is greatly improved. In addition, strong alkali can be subjected to an efficient chemical reaction with the layered material under mechanical action, and a hydroxyl functional group is grafted at a defect position of the layered material, so that the layered material is easier to strip off under the action of mechanical force.

Description

Two-dimensional material, preparation method and application thereof

technical field

The present application relates to the technical field of two-dimensional materials, in particular to two-dimensional materials and their preparation methods and applications.

Background technique

Two-dimensional materials are generally considered to be nanomaterials with a single dimension less than ten atomic layers, and the remaining two dimensions are tens of nanometers to tens of micrometers. Due to the quantum size effect, edge effect, surface effect, and macroscopic quantum tunneling effect of two-dimensional materials, they have some special properties that are different from the original ones, and have broad application prospects in many fields. In recent years, the unique properties of 2D materials such as graphene, hexagonal boron nitride, molybdenum disulfide, tungsten disulfide, and black scale have brought new developments to the field of materials science. Single-layer or few-layer graphene has extremely high mechanical strength, excellent light transmittance, high electron mobility, and high thermal conductivity. Two-dimensional boron nitride nanosheets have an atomic structure similar to graphene, also known as white graphene. Two-position boron nitride nanosheets also have high mechanical strength, thermal conductivity and other characteristics, but white graphene is an excellent insulating material and has unique advantages such as high thermal stability and chemical stability. It is used in electronic insulation and heat dissipation, coating anti-corrosion and other applications. Two-dimensional molybdenum disulfide has good lubricating properties, and its sandwich-like two-dimensional structure is expected to bring great changes to many fields such as optoelectronic materials and composite materials.

The preparation of 2D materials can be divided into top-down and bottom-up synthesis methods. Top-down methods include mechanical exfoliation and chemical exfoliation. Mechanical exfoliation is the exfoliation of two-dimensional materials by mechanical force. The representative processes include ultrasonic method, ball milling method, high pressure homogenization method, and microfluidic method. Chemical exfoliation is to achieve effective exfoliation of two-dimensional materials by chemical modification of two-dimensional layered materials, including oxidation intercalation method, ion intercalation method, molten alkali method, etc. From bottom to top, chemical vapor deposition and other methods are used to prepare two-dimensional boron nitride thin films on specific substrates. The materials prepared by the traditional top-down method have poor peeling quality and small sheet size, making the final performance difficult to meet expectations. Therefore, it is necessary to provide a preparation method of two-dimensional materials that can obtain larger sheet size.

SUMMARY OF THE INVENTION

The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a two-dimensional material with a larger sheet size and a preparation method and application thereof.

A first aspect of the present application provides a method for preparing a two-dimensional material, comprising the following steps: mixing the layered material with a strong alkali solution, and applying mechanical force to peel off to obtain a two-dimensional material.

The preparation method according to the embodiment of the present application has at least the following beneficial effects:

(1) The application utilizes a strong alkali solution as an aid for mechanically exfoliating the two-dimensional material, and the strong alkali can be adsorbed to the surface and edge of the layered material during the action of mechanical force, and the hydroxide anion therein drives the curling of the edge of the lamella. The cations are beneficial to intercalation into the layered material, further opening the interlayer spacing, and improving the peeling effect of the shearing action of mechanical force on the layered material. The strong alkali in the form of solution can improve its function as an auxiliary agent in the mechanical process, strengthen the transmission of mechanical force, and make the whole mechanical peeling process more efficient. Compared with pure mechanical peeling or existing mechanochemical methods, the synergistic effect of strong alkali additives and wet process is more obvious, effectively reducing the direct contact between mechanical force and layered materials, protecting the lamellae of layered materials, avoiding Excessive impact damage greatly increases the sheet size of two-dimensional materials.

(2) In addition, the strong base will have an efficient chemical reaction with the layered material under mechanical action. Compared with other hydroxyl-containing additives, the reaction ability is stronger, and the hydroxyl functional group grafted at the defect of the layered material is stronger. More, easier to peel off under mechanical force. In addition, the strong alkali has weak adsorption capacity for the layered material, and the final two-dimensional material has higher cleanliness.

Among them, the layered material refers to the material in which the interaction force between atoms in the sheet layer is very strong, while the interaction between atoms in different sheets is very weak, thus forming a layered structure with a thickness of nanometers or larger; Dimensional materials refer to materials with a layered structure consisting of only a single layer or a few atomic layers. Non-limiting examples of layered materials include graphite, black phosphorus, boron nitride, transition metal dichalcogenides (TMDs such as MoS ₂ , NbSe ₂ , VTe ₂ ), transition metal oxides such as MnO ₂ , MoO ₃ ), transition metal carbon (nitrogen) compounds (MXene, such as Ti ₃ C ₂ T _x ), Layered Double Hydroxides (Layered Double Hydroxides, LDHs, such as NiFe-LDH, MgFe-LDH), clay, Mica etc.

Strong bases refer to substances that can ionize all hydroxide ions after being dissolved in water, non-limiting examples thereof include inorganic strong bases and organic strong bases, and inorganic strong bases include alkali metal hydroxides (such as LiOH, NaOH, KOH, RbOH, CsOH, FrOH), some alkaline earth metal hydroxides (such as Ca(OH) ₂ , Sr(OH) ₂ , Ba(OH) ₂ , Ra(OH) ₂ ), etc., while organic strong bases include choline ([ HOCH ₂ CH ₂ N(CH ₃ ) ₃ ]OH), quaternary ammonium base (R ₄ NOH), etc.

Specific means of applying mechanical force include, but are not limited to, ball milling, sanding, grinding, sanding, rolling, mechanical stirring, high-speed shearing, sonication, high-pressure homogenization, micro-jetting, etc. that can provide shearing force to make layered materials The way of peeling by lateral sliding between two adjacent sheets.

In some embodiments of the present application, the following steps are included:

S1: mixing the layered material with a strong base to obtain a first mixture;

S2: applying mechanical force to the first mixture to obtain a pretreated product;

S3: disperse the pretreated product in a solvent to obtain a second mixture;

S4: applying mechanical force to the second mixture to exfoliate to obtain a two-dimensional material.

Wherein, the solvent in S3 refers to a solvent that can optionally cause ionization of strong bases to generate hydroxide ions, including water, lower alcohols (such as methanol, ethanol, etc.). First, the layered material is mixed with a strong base, and mechanical force is applied for pretreatment, so that a part of hydroxyl functional groups is pre-grafted at the defects of the layered material, so that the edge layer spacing is initially opened, which facilitates further mechanical force treatment in the subsequent solution state. Thus, the exfoliation effect of 2D materials is optimized.

In some embodiments of the present application, the mass ratio of solvent to pretreatment product is (0.5-5):1. The ratio of solvent to pretreatment product is related to the reaction between strong alkali solution and boron nitride in S4. When the ratio is between 0.5 and 5, the size of the exfoliated sheet is better.

In some embodiments of the present application, the mass ratio of the solvent to the pretreated product is (1-3):1.

In some embodiments of the present application, the mass ratio of the layered material to the strong base is 1:(0.1-50). The ratio of the amount of the layered material to the strong base affects the opening of the interlayer distance and the transmission of mechanical force during the reaction. When the mass ratio of the layered material to the strong base is 1: (0.1 to 50), the shear force brings The peeling effect is better.

In some embodiments of the present application, the mass ratio of the layered material to the strong base is 1:(1-20).

In some embodiments of the present application, the method of applying mechanical force in S2 is at least one of ball milling, rolling, grinding, sand milling, mechanical stirring, high-speed shearing, etc., preferably ball milling and/or grinding.

In some embodiments of the present application, the time for applying the mechanical force in S2 is 0.2-48 hours, preferably 0.5-2 hours.

In some embodiments of the present application, the method of applying mechanical force by S4 is at least one of wet ball milling, sand milling, ultrasonic treatment, high-pressure homogenization, micro-jet, mechanical stirring, high-speed shearing, etc., preferably wet method At least one of ball milling, sand milling, high-pressure homogenization, and high-speed shearing.

In some embodiments of the present application, the time for S4 to apply the mechanical force is 0.5-48 hours, preferably 6-24 hours.

In some embodiments of the present application, the mesh number of the layered material is 5-5000 mesh.

In some embodiments of the present application, the mesh of the layered material is 50-500 mesh.

In some embodiments of the present application, S4 further includes the steps of separation, washing and drying.

In some embodiments of the present application, the specific steps of separation, cleaning and drying are as follows:

The solid phase is separated from the mixed solution obtained by applying mechanical force, washed to remove unreacted raw materials, and dried to obtain a two-dimensional material.

Among them, non-limiting examples of the method for separating out the solid phase include centrifugation, natural sedimentation, positive pressure filtration, negative pressure filtration, ceramic membrane filtration and the like. Non-limiting examples of cleaning methods include 1 to 10 times of deionized water cleaning, preferably 2 to 5 times of cleaning. Non-limiting examples of drying means include blast drying, vacuum drying, freeze drying, spray drying, supercritical drying, etc., preferably at least one of vacuum drying, freeze drying and spray drying.

In some embodiments of the present application, the first mixture in S2 is also dried before being subjected to mechanical force.

In some embodiments of the present application, the drying process is performed at 40-300° C., preferably 100-250° C.; the treatment time of the drying process is 0.1-12 hours, preferably 0.5-2 hours.

In some embodiments of the present application, the strong base is an alkali metal hydroxide, including at least one of LiOH, NaOH, KOH, RbOH, CsOH, and FrOH.

In a second aspect of the present application, a two-dimensional material is provided, and the two-dimensional material is prepared by the above-mentioned preparation method.

The two-dimensional material according to the embodiment of the present application has at least the following beneficial effects:

The two-dimensional material prepared by the above method has a larger sheet size and higher cleanliness, so that the electrical, chemical, optical and mechanical properties of the two-dimensional material can be fully utilized.

A third aspect of the present application provides a composition comprising the above-mentioned two-dimensional material. Non-limiting examples of compositions include dispersions (ie, including a solvent and two-dimensional materials dispersed in the solvent) using the above-mentioned two-dimensional materials as the main raw materials, or composite materials prepared using the above-mentioned two-dimensional materials as part of the raw materials.

A fourth aspect of the present application provides applications of the above-mentioned two-dimensional materials in the preparation of optoelectronic devices, anti-corrosion coatings, and heat-dissipating devices.

Additional aspects and advantages of the present application will be set forth, in part, from the following description, and in part will become apparent from the following description, or may be learned by practice of the present application.

Description of drawings

FIG. 1 is a TEM image of the boron nitride nanosheets prepared in Example 1 of the present application.

FIG. 2 is a TEM image of the boron nitride nanosheets prepared in Comparative Example 1 of the present application.

FIG. 3 is an FTIR image of the boron nitride nanosheet powder prepared in Example 2 of the present application.

FIG. 4 is a TEM image of the microcrystalline graphite nanosheet prepared in Example 3 of the present application.

Detailed ways

The concept of the present application and the resulting technical effects will be clearly and completely described below with reference to the embodiments, so as to fully understand the purpose, features and effects of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative work belong to The scope of protection of this application.

The embodiments of the present application will be described in detail below. The described embodiments are exemplary and are only used to explain the present application, but should not be construed as a limitation on the present application.

In the description of this application, the meaning of several is more than one, the meaning of multiple is two or more, greater than, less than, exceeding, etc. are understood as not including this number, above, below, within, etc. are understood as including this number. If it is described that the first and the second are only for the purpose of distinguishing technical features, it cannot be understood as indicating or implying relative importance, or indicating the number of the indicated technical features or the order of the indicated technical features. relation.

In the description of this application, unless otherwise clearly defined, terms such as setting, installation, and connection should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in this application in combination with the specific content of the technical solution.

In the description of this application, references to the terms "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples", etc., are meant to incorporate the embodiments A particular feature, structure, material, or characteristic described or exemplified is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Example 1

This embodiment provides a two-dimensional material and a preparation method thereof, the two-dimensional material is boron nitride nanosheets, and the preparation method of the two-dimensional material includes the following steps:

S1: Mix 10 g of sodium hydroxide powder and 1 g of boron nitride powder uniformly to obtain a first mixture.

S2: Add the first mixture together with 100g of 95% zirconia balls with a diameter of 10mm and 25g into a 250ml zirconia ball mill jar, and after sealing, ball-mill at a speed of 500rpm on a QM-3SP2 planetary ball mill for 1 hour to obtain a Process the product.

S3: Add 10 ml of deionized water to the ball mill jar containing the pretreated product to obtain a second mixture.

S4: Continue ball milling at a speed of 500 rpm for 12 hours after sealing, and take out the ball-milled product in the ball-milling jar after the ball-milling is completed.

After the ball milled product was washed with 300ml deionized water, filtered with a microporous membrane, the filter cake was repeatedly washed and filtered for 4 times, and centrifuged at 2000 rpm for 10 minutes, and the supernatant was drawn to obtain water for functionalized boron nitride nanosheets. Dispersions. An appropriate amount of the aqueous dispersion was filtered, and dried at 60 °C for 12 h to obtain a powder of functionalized boron nitride nanosheets.

In step S2, after the ball milling is completed, the ball mill jar is taken out, and the generation of ammonia gas is found through the smell, indicating that an obvious mechanochemical reaction has occurred between boron nitride and sodium hydroxide.

FIG. 1 is a TEM photo of the boron nitride nanosheets prepared in this example. It can be seen from the figure that the size of the boron nitride nanosheets is greater than 1 μm and the thickness is relatively thin.

Comparative Experiment

Comparative Example 1

This comparative example provides a preparation method of a two-dimensional material. The difference from Example 1 is that the process of applying mechanical force is different, and the specific steps are as follows:

S2: Add the first mixture together with 100g of 95% zirconia balls with a diameter of 10mm and 25g into a 250ml zirconia ball mill jar, and after sealing, ball mill at a speed of 500rpm on a QM-3SP2 planetary ball mill for 13 hours to obtain a ball mill product.

After the ball milling, take out the ball-milled product in the ball-milling jar, wash with 300ml of deionized water, filter with a microporous membrane, wash and filter the filter cake repeatedly for 4 times, and centrifuge at 2000rpm for 10 minutes, absorb the supernatant to obtain Aqueous dispersion of functionalized boron nitride nanosheets. An appropriate amount of the aqueous dispersion was filtered and dried at 60 °C for 12 h to obtain a powder of functionalized boron nitride nanosheets.

Figure 2 is a TEM photo of the boron nitride nanosheets prepared by the comparative example, A and B are boron nitride nanosheets of different sizes, respectively. It can be seen from the figure that the boron nitride nanosheets prepared by this method are Compared with Example 1, the size of the lamellae is smaller, basically below 100 nm. It is speculated that the reason may be due to the excessive reaction of boron nitride and sodium hydroxide in its process engineering, resulting in the resulting nanosheets with smaller size.

Example 2

S1: Weigh 5 g of sodium hydroxide powder and 5 g of potassium hydroxide powder, grind them uniformly, and mix them with 1 g of boron nitride powder to obtain a first mixture.

Fig. 3 is an FTIR photo of boron nitride nanosheets in this embodiment, the upper part is the detection result of two-dimensional boron nitride nanosheets, and the lower part is the detection result of bulk boron nitride. Compared with the bulk boron nitride, the two-dimensional boron nitride nanosheets have more B-OH peak positions, indicating that during the preparation process, when the strong alkali solution assisted the exfoliation, part of the hydroxide ions were grafted to the boron nitride. Hydroxyl functional groups are formed on the lamellae.

Example 3

S1: Mix 10 g of sodium hydroxide powder and 1 g of graphite powder uniformly to obtain a first mixture.

FIG. 4 is a TEM photograph of the graphite nanosheets prepared in this example. It can be seen from the figure that the thickness of the graphite nanosheets prepared by this method is thin, and the sheet size is 1-2 μm.

Example 4

This embodiment provides a two-dimensional material and a preparation method thereof, the two-dimensional material is molybdenum disulfide nanosheets, and the preparation method of the two-dimensional material includes the following steps:

S1: Weigh 2 g of sodium hydroxide powder and 8 g of barium hydroxide powder, grind them uniformly, and mix them with 1 g of molybdenum disulfide powder to obtain a first mixture.

S3: Add 50 ml of deionized water to the ball mill jar containing the pretreated product to obtain a second mixture.

After the ball-milled product was washed with 300ml deionized water, filtered with a microporous membrane, the filter cake was repeatedly washed and filtered for 4 times, and centrifuged at 2000rpm for 10 minutes, and the supernatant was drawn to obtain water for functionalized molybdenum disulfide nanosheets. Dispersions. An appropriate amount of the aqueous dispersion was filtered and dried at 60 °C for 12 h to obtain the powder of functionalized molybdenum disulfide nanosheets.

According to transmission electron microscopy, the size of the molybdenum disulfide nanosheets is 0.5-4 μm, and the thickness is relatively thin.

Example 5

This embodiment provides a two-dimensional material and a preparation method thereof. The two-dimensional material is two-dimensional black phosphorus nanosheets. The preparation method of the two-dimensional material includes the following steps:

S1: Weigh 30 g of sodium hydroxide powder and 20 g of sodium hydroxide powder, grind them uniformly, and mix them with 1 g of black phosphorus powder to obtain a first mixture.

S2: The first mixture is placed in a high-speed shearing machine and processed at a speed of 5000 rpm for 1 hour to obtain a pretreated product.

S3: Add 200 ml of deionized water to the pretreated product, continue to treat at a speed of 5000 rpm for 12 hours, and take out the high-speed shearing product.

After the high-speed shearing product was washed with 300 ml of deionized water, filtered with a microporous membrane, the filter cake was repeatedly washed and filtered for 4 times, and centrifuged at 2000 rpm for 10 minutes, and the supernatant was drawn to obtain functionalized molybdenum disulfide nanosheets of water dispersion. An appropriate amount of the aqueous dispersion was filtered and then freeze-dried to obtain a powder of functionalized two-dimensional black phosphorus nanosheets.

According to transmission electron microscopy, the size of the two-dimensional black phosphorus nanosheets is 0.1-5 μm, and the thickness is relatively thin.

Example 6

This embodiment provides a two-dimensional material and a preparation method thereof, the two-dimensional material is a two-dimensional MXene nanosheet, and the preparation method of the two-dimensional material includes the following steps:

S1: Take 0.1 g of sodium hydroxide powder and mix uniformly with 1 g of the multi-layer MXene material to obtain a first mixture.

S2: grinding the first mixture for 30 min to obtain a pretreated product.

S3: Add 5 ml of deionized water to the pretreated product, and mix uniformly to obtain a second mixture.

S4: Pass the second mixture through a microfluidic homogenizer at a pressure of 80-200 Mpa, and perform a cyclic treatment for 30 hours, and take out the microfluidic product.

The microfluidic product was washed with 300 ml of deionized water, filtered with a microporous membrane, and the filter cake was repeatedly washed and filtered for 4 times, and centrifuged at 2000 rpm for 10 minutes, and the supernatant was drawn to obtain functionalized molybdenum disulfide nanosheets. Aqueous dispersion. An appropriate amount of the aqueous dispersion was filtered and spray-dried to obtain a powder of functionalized two-dimensional MXene nanosheets.

Through transmission electron microscopy, the size of the two-dimensional MXene nanosheets is 1-10 μm, and the thickness is relatively thin.

In summary, the sheet size of the two-dimensional materials prepared in the examples of the present application is about 0.1-10 μm, the thickness is about 0.33-50 nm, and the edges have functional groups, which is conducive to the dispersion of the two-dimensional materials in the aqueous solution and facilitates subsequent diversification. processing method.

Example 7

This embodiment provides a heat dissipation film, and the preparation raw materials of the heat dissipation film include 30 wt % of polyurethane elastomer, 40 wt % of the two-dimensional boron nitride nanosheets in Embodiment 1 or 2, and 30 wt % of carbon nanotubes.

The present application has been described in detail above in conjunction with the embodiments, but the present application is not limited to the above-mentioned embodiments, and within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the purpose of the present application. Furthermore, the embodiments of the present application and features in the embodiments may be combined with each other without conflict.

Claims

The method for preparing a two-dimensional material is characterized by comprising the following steps: mixing the layered material with a strong alkali solution, and applying mechanical force to peel off to obtain a two-dimensional material.
preparation method according to claim 1, is characterized in that, comprises the following steps:

S1: mixing the layered material with the strong base to obtain a first mixture;

S2: applying mechanical force to the first mixture to obtain a pretreated product;

S3: Disperse the pretreated product in a solvent to obtain a second mixture;

S4: applying mechanical force to the second mixture for exfoliation to obtain the two-dimensional material.
The preparation method according to claim 2, wherein the mass ratio of the solvent to the pretreated product is (0.5-5):1.
The preparation method according to any one of claims 1 to 3, wherein the mass ratio of the layered material to the strong base is 1:(0.1-50).
The preparation method according to any one of claims 1 to 3, wherein the mesh number of the layered material is 5-5000 mesh.
The preparation method according to any one of claims 1 to 3, wherein the S4 further comprises the steps of separation, cleaning and drying.
The preparation method according to any one of claims 1 to 3, wherein the strong base is an alkali metal hydroxide.
The two-dimensional material is characterized in that, it is prepared by the preparation method described in any one of claims 1 to 7.
The composition is characterized by comprising the two-dimensional material of claim 8 .
Application of the two-dimensional material according to claim 8 in the preparation of optoelectronic devices, anti-corrosion coatings, and heat-dissipating devices.