CN107585749B - Boron nitride nanosheet powder, green macro-preparation method and application thereof - Google Patents

Abstract

The invention discloses a boron nitride nano-sheet powder, a green macro-scale preparation method and application thereof. The green macro-mass preparation method includes: mixing a boron source and a carrier as a precursor, heating the temperature to 700-1100 DEG C in an ammonia gas atmosphere and maintaining the temperature for 60-180 min, and then lowering it to room temperature in a protective atmosphere to obtain a crude product, The obtained crude product is subjected to post-processing to obtain a large amount of pure boron nitride nanosheet powder. The boron source includes boron oxide, and the carrier includes sodium chloride and/or potassium chloride. The preparation process of the invention is simple, green and pollution-free, the raw materials are cheap and easy to obtain, safe and non-toxic, the conversion rate of the boron source can reach 89%, and the obtained boron nitride nanosheet powder is hexagonal boron nitride nanosheet, and its purity is More than 99%. By virtue of the present invention, gram-level batch green production of high-purity boron nitride nanosheet powder can be realized.

Description

Boron nitride nanosheet powder, its green macro preparation method and application

technical field

The invention specifically relates to a method for preparing boron nitride nano flake powder in green and macro quantities, and belongs to the technical field of inorganic nano materials.

Background technique

The structure of boron nitride is similar to graphite, and both belong to the hexagonal crystal system. The B atoms and N atoms in the plane are bound by covalent bonds, and the atoms between the planes are bound by van der Waals forces. The boron nitride family contains many members such as boron nitride nanosheets, boron nitride nanotubes, boron nitride nanobelts, boron nitride aerogels, boron nitride quantum dots, etc. Among them, hexagonal boron nitride nanosheets are a kind of Important wide-bandgap semiconductor material, its forbidden band width reaches 5-6eV, and has excellent physical and chemical properties, such as excellent thermal conductivity, chemical stability, excellent insulation, hydrophobicity, large specific surface area, good It can be widely used in high-tech fields such as machinery, electronics, aerospace, biomedicine and so on. Obviously, these remarkable properties of boron nitride nanosheets bring great potential not only for fundamental research, but also for the development of advanced materials and wider practical applications. Therefore, the preparation of boron nitride nanosheets has become one of the important research directions in the field of boron nitride nanomaterials.

According to reports, Pacil prepared boron nitride nanosheets by mechanical exfoliation for the first time. The specific method is to adhere hexagonal boron nitride powder with a particle size of 10um to a silica substrate with a thickness of 300nm with tape, and then forcibly The boron nitride separates into small fragments, resulting in two-dimensional boron nitride nanosheets that are only a few atomic layers thick. After that, some researchers developed a variety of methods and technologies to prepare boron nitride nanosheets, such as ball milling, ultrasonic-assisted lift-off, chemical vapor deposition, wet chemical methods, and so on. Compared with the mechanical exfoliation method, the ball milling method can obtain a larger number of boron nitride nanosheets. For example, Li et al. reported a mild wet ball milling method, which yielded boron nitride nanosheets with a thickness of several atomic layers with a slightly reduced size and good crystallinity of the nanosheet layers. For another example, Lin et al. demonstrated that under the aid of ultrasound, water can effectively exfoliate boron nitride, and water-soluble boron nitride nanosheets can be obtained without adding any surfactant and functional modification. The preparation of boron nitride nanosheets by chemical vapor deposition can be traced back to 1968. Rand et al. used diborane (B ₂ H ₆ ) and ammonia (NH ₃ ) as precursors to deposit at 600-1080 °C. on different substrates. For the wet chemical method, Rao et al. prepared boron nitride nanosheets with a thickness of several atomic layers using boric acid (H ₃ BO ₃ ) and urea (CO(NH ₂ ) ₂ ) heated to 900 °C under N ₂ protection.

Although there are many methods for preparing boron nitride nanosheets, it is difficult to achieve a balance in terms of yield, cost, crystallinity, and environmental protection, which largely limits the application of boron nitride nanosheets.

Therefore, there is an urgent practical need to develop a green and macro method for preparing boron nitride nanosheet powders.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a boron nitride nanosheet powder, its green macro-scale preparation method and application, so as to overcome the deficiencies in the prior art.

In order to realize the foregoing invention purpose, the technical scheme adopted in the present invention includes:

The embodiment of the present invention provides a green macro method for preparing boron nitride nanosheet powder, which includes:

Provide a precursor mainly formed by fully mixing a boron source and a carrier, the boron source includes boron oxide, and the carrier includes sodium chloride and/or potassium chloride;

The precursor is heated to 700-1100° C. in an ammonia gas atmosphere, kept in the atmosphere for 60-180 min, and then lowered to room temperature in a protective atmosphere to obtain a crude product, and the crude product is subjected to post-processing, Obtain a large amount of pure boron nitride nanosheet powder.

In a preferred embodiment, the boron source is boron oxide.

In a preferred embodiment, the carrier is sodium chloride and/or potassium chloride.

The embodiment of the present invention also provides the boron nitride nanosheet powder prepared by the method.

The embodiment of the present invention also provides the use of the boron nitride nanosheet powder.

Compared with the prior art, the advantages of the present invention include: the provided process for preparing boron nitride nanosheet powder in a green mass is simple and easy to operate, the reaction can be completed in only one step to obtain a powdery crude product, and the The raw material is boron oxide and a carrier (sodium chloride and/or potassium chloride), which has the advantages of low price, easy purchase, green and pollution-free, easily soluble in water, etc., and the conversion rate of boron oxide in the raw material is more than 89% , the green preparation of gram-scale boron nitride nanosheet powder can be easily realized in a single batch reaction, and the post-processing operation of the obtained crude product is simple and environmentally friendly, and the purity of the target product obtained after treatment is as high as 99%.

Description of drawings

FIG. 1 is a real photo of the crude product of boron nitride nanosheets without water washing obtained in Example 1.

Fig. 2 is a real photo of boron nitride nanosheets obtained by post-processing of the crude product obtained in Example 1.

3 is an XRD pattern of the boron nitride nanosheets obtained in Example 1 after water washing.

4a-4b are the SEM and TEM images of the large boron nitride nanosheets obtained in Example 1, respectively.

5a-5b are the SEM and TEM images of the small-layer boron nitride nanosheets obtained in Example 1, respectively.

FIG. 6 is an XRD pattern of the boron nitride nanosheets obtained in Example 2. FIG.

FIG. 7 is a real photo of boron nitride nanosheets obtained by post-processing of the crude product in Example 3. FIG.

FIG. 8 is a real photo of the crude product of boron nitride nanosheets without water washing obtained in Example 4. FIG.

9 is an XRD pattern of the boron nitride nanosheets obtained in Example 4 after water washing.

FIG. 10 is a SEM image of the boron nitride nanosheets obtained in Example 5. FIG.

Detailed ways

In view of the deficiencies in the prior art, the inventor of the present solution, after a lot of research and long-term exploration, proposes the technical solution of the present invention, which mainly relates to a method for preparing boron nitride nanosheet powder in a green mass, as follows be described in detail.

A method for preparing boron nitride nanosheet powder in a green macro-scale provided by the embodiment of the present invention includes:

Provide a precursor mainly formed by fully mixing a boron source and a carrier, the boron source includes boron oxide, and the carrier includes sodium chloride and/or potassium chloride;

The precursor is heated to 700-1100° C. in an ammonia gas atmosphere, and the reaction is maintained in an ammonia gas atmosphere, and then lowered to room temperature in a protective atmosphere to obtain a crude product, and the crude product is subjected to post-treatment to obtain A large amount of pure boron nitride nanosheet powder.

More preferably, the mass ratio of the boron source to the carrier is 1:3.

More preferably, the boron source is boron oxide.

More preferably, the carrier is sodium chloride and/or potassium chloride.

In some preferred embodiments, the post-treatment includes: after soaking the crude product in deionized water for 30-60 minutes, separating out the solids, and drying at 40-60° C. for 60-120 minutes to obtain a large amount of Pure boron nitride nanosheet powder.

Wherein, the method for separating the solid matter may be filtration, centrifugation, etc., but is not limited thereto.

Further, the protective atmosphere can be selected from an inert atmosphere, such as an argon atmosphere.

Further, the pure boron nitride nanosheet powder is a hexagonal boron nitride nanosheet with a purity of more than 99%.

In some embodiments, the green preparation method includes: using a mixture of boron oxide and sodium chloride as a precursor, and the obtained pure boron nitride nanosheet powder includes densely arranged hexagonal nitride with a size of 90-120 nm Boron nanosheets and hexagonal boron nitride nanosheets with a content of less than 5 wt% and a size of 20-50 μm.

In some preferred embodiments, the green preparation method includes: using a mixture of boron oxide and potassium chloride as a precursor, and the obtained pure boron nitride nanosheet powder is uniform and hexagonal with a size of 90-120 nm. boron nitride nanosheets.

That is, in some embodiments, if a mixture of boron oxide and sodium chloride is used as the precursor, the hexagonal boron nitride nanosheets contain two morphologies: one is a densely arranged platelet layer, and one is a It is a thin large layer; if the mixture of boron oxide and potassium chloride is used as the precursor, the hexagonal boron nitride nanosheets are uniform small nanosheets.

In some specific implementation cases of the present invention, a green macro method for preparing boron nitride nanosheet powder includes the following steps:

(1) The boron source and the carrier are fully mixed and used as a precursor, heated to 700-1100°C in an ammonia gas atmosphere, and kept for 60-180 minutes, and then cooled to room temperature in an argon gas protective atmosphere to obtain powder. the crude product.

(2) Washing, filtering and drying the crude product obtained in step (1) to obtain boron nitride nanosheet powder with a purity of more than 99%.

By adjusting the ratio and dosage of boron oxide and the carrier, the yield of pure boron nitride nanosheet powder obtained in a single batch can reach above the gram level.

In a specific scheme, the preparation method involves the following chemical reactions:

B2O3+ _{2NH3 → 2BN} + _3H2O .

The reaction temperature in step (1) is preferably 1000-1100° C., and the product has good crystallinity.

The washing and filtration described in step (2) are preferably as follows: 2-3 times of deionized water washing is added during the filtration process, which can improve the purity of the boron nitride nanosheet powder.

The drying described in step (2) is preferably: drying at 60°C.

The embodiment of the present invention also provides the boron nitride nanosheet powder prepared by the method.

The hexagonal boron nitride nanosheets obtained by the method of the present invention can be used in many fields such as electronic packaging insulating and heat-dissipating materials, heat-conducting oil fillers, heat-conducting insulating fillers of composite materials, lubricating materials, drug loads, catalyst carriers and the like.

The technical solutions of the present invention will be described in more detail below in conjunction with the accompanying drawings and some typical embodiments:

Example 1 Mix 0.3g B ₂ O ₃ with 0.5g NaCl thoroughly, place it in an open alumina crucible, then put it into a quartz tube of a tube furnace, and feed 200 standard milliliters/minute (sccm) of NH ₃ , heated to 1100 °C. After 120 min of constant temperature reaction at 1100 °C, the NH ₃ was turned off, 200 sccm of Ar was introduced, and the mixture was cooled to room temperature in an Ar atmosphere, and the obtained crude product was taken out. The obtained crude product is soaked and cleaned in deionized water for 30-60 minutes, vacuum filtered, and dried in an oven at 60° C. for 60-120 minutes to obtain boron nitride nanosheet powder with a purity of more than 99%. FIG. 1 is a real photo of the unwashed boron nitride nanosheet crude product obtained in this example. Fig. 2 is a real photo of boron nitride nanosheets obtained by post-processing of the crude product of the present embodiment. FIG. 3 shows the XRD pattern of the boron nitride nanosheets obtained in this example after washing with water, and it can be confirmed that the product is hexagonal boron nitride. 4a-4b are SEM and TEM images of the boron nitride nanosheets obtained in this embodiment, respectively, and large sheets of boron nitride nanosheets can be observed. 5a-5b are the SEM and TEM images of the BNNS obtained in the present embodiment, and boron nitride nanosheets in the small sheet layer can be observed.

Example 2 Take 0.3g B ₂ O ₃ and 0.5g NaCl and mix well, place it in an open alumina crucible, then put it into a quartz tube of a tube furnace, pass 200 standard milliliters/minute (sccm) of NH ₃ , heated to 700°C. After 120 min of constant temperature reaction at 700° C., the NH ₃ was turned off, 200 sccm of Ar was introduced, and the mixture was cooled to room temperature in an Ar atmosphere, and the obtained crude product was taken out. The obtained crude product is soaked and cleaned in deionized water for 30-60 minutes, vacuum filtered, and dried in an oven at 60° C. for 60-120 minutes to obtain boron nitride nanosheet powder with a purity of more than 99%. FIG. 6 is an XRD pattern of the boron nitride nanosheets obtained in this example.

Example 3 Take 1.2g of B ₂ O ₃ and 8.4g of NaCl, grind them slightly with a mortar and mix them well, place them in an open alumina crucible, then put them into a quartz tube of a tube furnace, and pour 200 standard ml/ minutes (sccm) of _NH3 , warming to 1100°C. After 180 min of constant temperature reaction at 1100°C, the NH ₃ was turned off, 200 sccm of Ar was introduced, and the mixture was cooled to room temperature in an Ar atmosphere, and the obtained crude product was taken out. The obtained crude product is soaked and cleaned in deionized water for 30-60 minutes, vacuum filtered, and dried in an oven at 60° C. for 60-120 minutes to obtain boron nitride nanosheet powder with a purity of more than 99%. In this example, the conversion rate of boron oxide can reach 89%. FIG. 7 is a real photo of boron nitride nanosheets obtained by post-processing of the crude product of the present embodiment.

Example 4 Take 0.3g of B ₂ O ₃ and 0.5g of NaCl, grind them slightly with a mortar and mix them well, place them in an open alumina crucible, then put them into a quartz tube of a tube furnace, and pour 200 standard ml/ minutes (sccm) of Ar, heated to 700 ℃, turned off the argon gas, introduced 200 sccm of NH ₃ , turned off the NH ₃ after 120 min of constant temperature reaction at 700 ℃, introduced 200 sccm of Ar, lowered it to room temperature in an Ar atmosphere, and took out the obtained crude product. The obtained crude product is soaked and cleaned in deionized water for 30-60 minutes, vacuum filtered, and dried in an oven at 60° C. for 60-120 minutes to obtain boron nitride nanosheet powder with a purity of more than 99%. FIG. 8 is a real photo of the crude product of boron nitride nanosheets without water washing obtained in this example. FIG. 9 is an XRD pattern of the boron nitride nanosheets obtained in this example after washing with water.

Example 5 Take 0.3g B ₂ O ₃ and 0.5g KCl and mix well, place it in an open alumina crucible, then put it into a quartz tube of a tube furnace, and pass 200 standard milliliters/minute (sccm) of NH ₃ , heated to 1100 °C. After 120 min of constant temperature reaction at 1100 °C, the NH ₃ was turned off, 200 sccm of Ar was introduced, and the mixture was cooled to room temperature in an Ar atmosphere, and the obtained crude product was taken out. The obtained crude product is soaked and cleaned in deionized water for 30-60 minutes, vacuum filtered, and dried in an oven at 60° C. for 60-120 minutes to obtain boron nitride nanosheet powder with a purity of more than 99%. FIG. 10 is an SEM image of the boron nitride nanosheets obtained in this example.

The above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the embodiments of the present invention, and it is not necessary and impossible to exhaust all the embodiments here. For those skilled in the art, changes or modifications in other different forms can also be made on the basis of the above description. However, any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (5)

1. a method for preparing boron nitride nanosheet powder in green macro quantity, is characterized in that comprising: Provide a precursor mainly formed by fully mixing a boron source and a carrier, the boron source includes boron oxide, the carrier is selected from sodium chloride and/or potassium chloride, and the mass ratio of the boron source to the carrier is 3:1 ~1:7; The precursor is heated to 700-1100° C. in an ammonia gas atmosphere, and kept for 60-180 min in an ammonia gas atmosphere, and then lowered to room temperature in a protective atmosphere to obtain a crude product, and the crude product is subjected to post-processing , to obtain a large amount of pure boron nitride nanosheet powder, and the pure boron nitride nanosheet powder is hexagonal boron nitride nanosheet with a purity of more than 99%; Using the mixture of boron oxide and sodium chloride as the precursor, the obtained pure boron nitride nanosheet powder includes densely arranged hexagonal boron nitride nanosheets with a size of 90-120 nm and hexagonal boron nitride nanosheets with a content of less than 5wt% and a size of 20-50µm hexagonal boron nitride nanosheets; A mixture of boron oxide and potassium chloride is used as a precursor, and the obtained pure boron nitride nanosheet powder is hexagonal boron nitride nanosheets with a size of 90-120 nm. 2 . The method for preparing boron nitride nanosheet powder in green macro quantities according to claim 1 , wherein the post-processing comprises: after soaking the crude product in deionized water for 30 to 60 min, separating the The solid matter is obtained and dried at 40-60°C for 60-120 min to obtain a macro amount of pure boron nitride nanosheet powder. 3 . The method for preparing boron nitride nanosheet powder in green macro quantities according to claim 1 , wherein the protective atmosphere is selected from an inert atmosphere. 4 . 4. The boron nitride nanosheet powder prepared by the method of any one of claims 1-3. 5. Use of the boron nitride nanosheet powder according to claim 4 in the preparation of electronic packaging insulating heat-dissipating materials, heat-conducting oil fillers, thermally-conducting insulating fillers of composite materials, lubricating materials, drug-carrying materials or catalyst carriers.

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