阅读说明：本技术 一种硼烯纳米片及其制备方法 (Boron alkene nanosheet and preparation method thereof ) 是由 蒋旭 董大鹏 顾振光 季锐 田瑞雪 于 2020-12-11 设计创作，主要内容包括：本发明公开一种硼烯纳米片及其制备方法,主要解决目前从硼粉制备二维硼烯纳米片的难题。该硼烯纳米片具有典型的二维层状结构,其厚度在0.3nm到10μm,其横向尺寸在100nm到100μm,硼元素的质量含量大于90%。所述制备方法包括：提供硼粉,将硼粉加入到溶剂中在水浴中超声,然后将得到的产物加入到浓酸中超声,经过离心干燥得到插层产物。然后将插层产物经过高温膨胀得到膨胀硼粉。最后将膨胀硼粉经过液相剥离得到硼烯纳米片。本发明提供了一种简单、绿色、高效、低成本方法制备硼烯纳米片,亦可以实现规模化生产。(The invention discloses a boron alkene nano-sheet and a preparation method thereof, which mainly solve the problem of preparing a two-dimensional boron alkene nano-sheet from boron powder at present. The boron-alkene nanosheet has a typical two-dimensional layered structure, the thickness of the boron-alkene nanosheet is 0.3nm to 10 microns, the transverse dimension of the boron-alkene nanosheet is 100nm to 100 microns, and the mass content of boron is more than 90%. The preparation method comprises the following steps: providing boron powder, adding the boron powder into a solvent, performing ultrasonic treatment in a water bath, adding the obtained product into concentrated acid, performing ultrasonic treatment, and performing centrifugal drying to obtain an intercalation product. And then expanding the intercalation product at high temperature to obtain expanded boron powder. And finally, stripping the expanded boron powder through a liquid phase to obtain the boron-alkene nanosheet. The invention provides a simple, green, efficient and low-cost method for preparing the boron alkene nanosheet, and can also realize large-scale production.)

1. The boron alkene nanosheet is characterized by having a typical two-dimensional layered structure, the thickness of the boron alkene nanosheet is 0.3nm-10 microns, the transverse dimension of the boron alkene nanosheet is 10nm-100 microns, and the mass content of boron elements is more than 90%.

2. A borolene nanoplatelet according to claim 1 wherein the thickness is from 0.8nm to 20nm, the lateral dimension is from 50nm to 10 μ ι η, the apparent density of the borolene nanoplatelet is 0.01g/cm³-100g/cm³。

3. A method of preparing a borolene nanoplatelet according to claim 1 or 2 comprising the steps of:

firstly, adding boron powder into a solvent to prepare a dispersion liquid, and then carrying out ultrasonic treatment in a water bath;

secondly, adding the obtained product into concentrated acid to form concentrated acid suspension, then carrying out ultrasonic treatment, and then carrying out centrifugal drying to obtain an intercalation product;

thirdly, heating and expanding the intercalation product to obtain expanded boron powder;

and fourthly, stripping the expanded boron powder through a liquid phase to obtain the boron-alkene nanosheet.

4. The method for preparing a borolene nanoplate according to claim 3, wherein in the first step, the particle size of the boron powder is 3000 mesh to 20 mesh, the content of boron element is more than 90%, and the apparent density is 0.1g/cm³-100g/cm³。

5. A method of producing a borolene nanoplatelet as in claim 3 wherein in the first step the solvent comprises any one or a combination of any two or more of water, ethanol, isopropanol, DMF, NMP or acetonitrile.

6. The preparation method of a boron alkene nano-sheet according to claim 3, wherein the concentration of the dispersion prepared by adding the boron powder into the solvent in the first step is 20 mg/L-1.2 g/mL.

7. The method for preparing a borolene nano sheet according to claim 3, wherein the concentrated acid in the second step comprises one or a combination of any two or more of sulfuric acid, hydrochloric acid, phosphoric acid and perchloric acid, and the mass percentage concentration of the concentrated acid is 15-65%.

8. The method of preparing a borolene nanoplatelet of claim 3 wherein the concentration of the concentrated acid suspension formed in the second step is comprised between 50mg/mL and 800 mg/mL.

9. The method of preparing a borolene nanoplatelet of claim 3 wherein the temperature rise of the temperature program in the third step is in the range of 100 ℃ to 1000 ℃, wherein the temperature program comprises several temperature zones, wherein the temperature range of each temperature zone is less than 300 ℃ and the temperature rise rate of the temperature program is in the range of 0.1 ℃ to 50 ℃.

10. The method for preparing a borolene nanoplatelet of claim 3 wherein the liquid phase exfoliation in the fourth step comprises one or a combination of any two or more of ultrasound, high speed stirring, homogenization or sanding.

Technical Field

The invention belongs to the technical field of nano materials, and particularly relates to a boron alkene nanosheet and a preparation method thereof.

Background

The two-dimensional material has huge application prospect in the fields of catalysis, energy, electronic information and the like due to excellent physical and chemical properties. The borolene is a new member of a two-dimensional material family, has the physicochemical properties of ultrahigh conductivity (which is approximately equal to 102 omega-1 cm-1), ultrahigh carrier migration rate (which is approximately equal to 102cm 2V-1 s-1), good thermal stability and the like, so that the borolene has attracted great attention in the fields of information, biomedicine and energy environment. At present, the preparation of two-dimensional boron alkene is mainly based on chemical vapor deposition (Angew. chem. int. Ed.,2015,54, 15473-. In order to realize the large-scale application of the borane, firstly, the low-cost batch preparation of the borane is realized. Boron is essentially a 3D element, the valence electron number is 3, but the atom orbital number is 4, so the valence electron number of boron is one less than the atom orbital number, the valence electron layer cannot be filled in the bonding process, and thus the boron atom belongs to an electron-deficient structure, so the boron atom usually forms a multi-center bond. This particular electronic structure of boron atoms contributes to the polyhedral nature of boron, which tends to form materials with complex polyhedral structures, rather than layered structures. The special structure of boron is different from that of the existing two-dimensional material, so that the process for preparing the boron alkene nanosheet by adopting a low-price large-volume liquid phase stripping method is more difficult. Currently, a liquid phase stripping method has been adopted by some research groups to prepare the boron-alkene nanosheets, for example, Sun et al adopts different organic solvents (chem.Commun.,2019,55, 4246-containing 4249; ACS Catal.2019,9, 4609-containing 4615) to carry out ultrasonic stripping on boron powder to obtain the boron-alkene nanosheets, but the stripping efficiency is very low, the final product concentration is only a few milligrams per milliliter, and the yield of large-scale preparation is far not achieved. How to realize the low-price large-scale preparation of the boron alkene nano-sheets is a key engineering problem which needs to be solved urgently in engineering application of boron alkene.

Disclosure of Invention

The invention mainly aims to provide a borolene nano-sheet and a preparation method thereof, so as to overcome the defects in the prior art.

In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

a boron-alkene nanosheet has a typical two-dimensional layered structure, the thickness of the boron-alkene nanosheet is 0.3nm-10 mu m, the transverse dimension of the boron-alkene nanosheet is 10nm-100 mu m, and the mass content of boron is greater than 90%.

Further, the thickness of the boron alkene nano-sheet is 0.8nm-20nm, the transverse dimension is 50nm-10 mu m, and the apparent density of the boron alkene nano-sheet is 0.01g/cm³-100g/cm³。

The preparation method of the borolene nano-sheet comprises the following steps:

firstly, adding boron powder into a solvent to prepare a dispersion liquid, and then carrying out ultrasonic treatment in a water bath;

secondly, adding the obtained product into concentrated acid to form concentrated acid suspension, then carrying out ultrasonic treatment, and carrying out centrifugal drying to obtain an intercalation product;

thirdly, heating and expanding the intercalation product to obtain expanded boron powder;

and fourthly, stripping the expanded boron powder through a liquid phase to obtain the boron-alkene nanosheet.

Further, in the preparation method of the boron alkene nano-sheet, in the first step, the particle size of the boron powder is 3000 meshes to 20 meshes, the content of boron element is more than 90 percent, and the apparent density is 0.1g/cm³-100g/cm³. Furthermore, the particle size of the boron powder is 500 meshes to 200 meshes, and the apparent density is 0.5g/cm³-10g/cm³。

Further, in the preparation method of the borane nanosheet, in the first step, the solvent comprises any one or a combination of any two or more of water, ethanol, isopropanol, DMF, NMP and acetonitrile. Further, the solvent includes a mixed solvent of ethanol and DMF and isopropyl alcohol and NMP in any ratio.

Further, in the preparation method of the boron alkene nano-sheet, in the first step, the concentration of a dispersion prepared by adding the boron powder into the solvent is 20 mg/L-1.2 g/mL.

Further, in the preparation method of the borolene nano-sheet, in the second step, the concentrated acid comprises one or a combination of any two or more of sulfuric acid, hydrochloric acid, phosphoric acid and perchloric acid, and the mass percentage concentration of the concentrated acid is 15-65%.

Further, in the preparation method of the boron alkene nano-sheet, the concentration of the concentrated acid suspension formed in the second step is 50 mg/mL-800 mg/mL.

Further, in the preparation method of the boron alkene nanosheet, in the third step, the temperature rise range of the programmed temperature rise is 100-1000 ℃, wherein the programmed temperature rise comprises a plurality of temperature zones, wherein the temperature range of each temperature zone is less than 300 ℃, and the temperature rise rate of the programmed temperature rise is 0.1-50 ℃. Furthermore, the temperature rise range is 250-600 ℃, the temperatures of the plurality of sections are 3-5 sections, the temperature range of each section is 50-200 ℃, and the temperature rise rate is 2-20 ℃.

Further, in the preparation method of the boron alkene nano-sheet, the liquid phase stripping manner in the fourth step includes one or a combination of any two or more of ultrasound, high-speed stirring, homogenization and sanding. Furthermore, the ultrasonic power is 100 to 1500W, the ultrasonic temperature is 10 to 50 ℃, the high-speed stirring speed is 100 to 30000Rpm, and the homogenizing pressure is 50 to 500 MPa.

The invention realizes the large-scale preparation of the boron-alkene nano-sheet by three processes of intercalation-expansion-stripping. The key point of the preparation of the boron alkene nanosheet is that the interlayer distance of the boron alkene is gradually opened, and firstly, the boron powder is wetted by a proper solvent to enable solvent molecules to slowly permeate into the interlayer. The interlayer spacing is then further oxidised by concentrated acid. The first step is especially important to wet the boron powder by using a proper solvent, and if the intercalation is directly performed by using concentrated acid, the intercalation agent cannot enter the interlayer due to the difference of surface energy, so that the surface of the boron powder cannot be oxidized to obtain an intercalation product. And (3) carrying out temperature programming expansion subsequently to further open the interlayer distance, wherein the temperature programming is adopted to match the decomposition temperatures of different intercalators, and the temperature-raising rate is controlled to effectively alleviate the problem of edge oxidation of the boron-alkene nanosheets caused in the thermal expansion process.

Compared with the prior art, the invention has the advantages that:

(1) the method for preparing the boron alkene nanosheets is simple in process, green and environment-friendly, all reagents can be recycled, the boron alkene nanosheets are prepared through three steps of intercalation, expansion and stripping, used equipment is simple, industrial amplification production is easy to achieve, and the method has a wide market prospect;

(2) the boron alkene nanosheet is prepared by adopting a unique intercalation-expansion-stripping process method, so that the stripping efficiency is ensured, the high yield is realized, and the problem of low yield of the conventional liquid phase stripping is solved;

(3) the boron alkene nanosheet provided by the invention has the advantages of high quality, high purity, less impurities and easiness in batch preparation.

Drawings

FIG. 1a is a transmission electron micrograph of a borolene nanoplatelet obtained in example 1 of the present invention;

FIG. 1b is an atomic force microscope image of a borolene nanoplatelet obtained in example 1 of the present invention;

FIG. 2a is a transmission electron micrograph of a borolene nanoplatelet obtained in example 2 of the present invention;

FIG. 2b is an atomic force microscope image of a borolene nanoplatelet obtained in example 2 of the present invention;

FIG. 3a is a transmission electron micrograph of a borolene nanoplatelet obtained in example 3 of the present invention;

FIG. 3b is an atomic force microscope image of a borolene nanoplatelet obtained in example 3 of the present invention;

FIG. 4a is a transmission electron micrograph of a borolene nanoplatelet obtained in example 4 of the present invention;

FIG. 4b is an atomic force microscope image of a borolene nanoplatelet obtained in example 4 of the present invention;

FIG. 5a is a transmission electron micrograph of a borolene nanoplatelet obtained in example 5 of the present invention;

FIG. 5b is an atomic force microscope image of a borolene nanoplatelet obtained in example 5 of the present invention.

The specific implementation mode is as follows:

in view of the deficiencies in the prior art, the inventors of the present invention have made extensive studies and extensive practices to provide technical solutions of the present invention. The technical solution and implementation process and principles etc. will be further explained as follows.

Aiming at a series of problems of low yield, high energy consumption, high production cost and the like in the existing preparation process of the boron alkene, the invention organically combines two methods of liquid phase stripping and high temperature expansion together to form a specific three-step preparation process of liquid phase intercalation-high temperature expansion-liquid phase stripping, thereby avoiding the defects of long yield period, high energy consumption equipment investment of chemical vapor deposition and the like of the traditional liquid phase stripping method. In order to further verify the performance of the prepared boron alkene, electron microscope detection is adopted to find that the transverse dimension of the boron alkene nanosheet is 10nm-100 mu m, and the thickness of the boron alkene nanosheet is 0.3nm-10 mu m; further, element tests show that the mass content of boron element in the prepared boron alkene is more than 90%; the apparent density of the boron-alkene nano-sheet is 0.01g/cm³-100g/cm³。

The preparation method of the borolene nano-sheet comprises the following steps:

firstly, the liquid phase intercalation is completed by two steps, firstly, the surface of boron powder is infiltrated into the interlayer by a solvent with the surface energy similar to that of the boron powder, and secondly, the intercalation is performed by concentrated acid. Different from the prior liquid phase stripping, the invention adopts a two-step intercalation method, wherein in the first step, a solvent with better wettability with boron powder is used for opening the edge of the layer, and then the interlayer is further expanded by acid intercalation. The two-step intercalation method is adopted to solve the problems that the interlayer spacing of the single solvent intercalation with good wettability is smaller and the solvent molecules are easy to separate, and simultaneously avoid the defect that the surface of boron powder particles is seriously oxidized because of the poor surface wettability because the single acid intercalation is adopted. Firstly, adding boron powder into a solvent to prepare a dispersion liquid, and then carrying out ultrasonic treatment in a water bath; then adding the obtained product into concentrated acid to form concentrated acid suspension, then carrying out ultrasonic treatment, and then carrying out centrifugal drying to obtain an intercalation product.

The particle size of the boron powder is 3000 meshes to 20 meshes, the content of boron element is more than 90 percent, and the apparent density is 0.1g/cm³-100g/cm³. Furthermore, the boron powder has a particle size of 500 meshes to 200 meshes and an apparent density of 0.5 g/mlcm³-10g/cm³。

The solvent comprises any one or the combination of any two of water, ethanol, isopropanol, DMF, NMP or acetonitrile. Further, the solvent includes a mixed solvent of ethanol and DMF and isopropyl alcohol and NMP in any ratio.

Furthermore, the concentration of the dispersion prepared by adding the boron powder into the solvent is 20 mg/L-1.2 g/mL.

Further, the concentrated acid comprises one or a combination of any two or more of sulfuric acid, hydrochloric acid, phosphoric acid and perchloric acid, and the mass percentage concentration of the concentrated acid is 15% -65%.

Furthermore, the concentration of the concentrated acid suspension is 50 mg/mL-800 mg/mL.

The intercalation product is obtained after the intercalation by a two-step method, and then the interlayer spacing is further opened through high-temperature expansion, so that the interlayer interaction force is weakened. In order to avoid the problem that raw materials are oxidized at high temperature or an intercalation overflows to cause poor expansion efficiency in the thermal expansion process due to one-step high-temperature expansion in the traditional thermal expansion method, the invention adopts a programmed heating expansion strategy, and performs gradual thermal expansion through the temperature matched with the boiling point and the decomposition temperature of the intercalation, so as to realize the maximization of the expansion effect. The temperature rise range of the programmed temperature rise adopted in the invention is 100-1000 ℃, wherein the programmed temperature rise comprises a plurality of temperature zones, the temperature range of each temperature zone is less than 300 ℃, and the temperature rise rate of the programmed temperature rise is 0.1-50 ℃. Furthermore, the temperature rise range is 250-600 ℃, the temperatures of the plurality of sections are 3-5 sections, the temperature range of each section is 50-200 ℃, and the temperature rise rate is 2-20 ℃. And finally obtaining the final boron alkene nanosheet through liquid phase stripping after obtaining an expansion product through temperature programming and expansion. The liquid phase stripping mode adopted in the invention comprises one or the combination of more than two of ultrasonic, high-speed stirring, homogenizing or sanding. Furthermore, the ultrasonic power is 100 to 1500W, the ultrasonic temperature is 10 to 50 ℃, the high-speed stirring speed is 100 to 30000Rpm, and the homogenizing pressure is 50 to 500 MPa. The boron-alkene nanosheets obtained through liquid phase stripping are subjected to electron microscope detection on the size and thickness of the diameter of the nanosheets and element detection to confirm the purity of the boron-alkene nanosheets.

The technical scheme of the invention is further explained in detail by a plurality of embodiments and the accompanying drawings.

Example 1

A preparation method of a borolene nano-sheet comprises the following steps:

firstly, adding a certain amount of boron powder into an ethanol/DMP mixed solvent to prepare a dispersion liquid, and then carrying out water bath ultrasound by adopting an ultrasonic instrument with the power of 500W, and keeping the temperature not to exceed 30 ℃ to obtain an ultrasonic mixed liquid;

secondly, adding a product obtained by filtering the ultrasonic mixed solution into concentrated acid to form concentrated acid suspension, performing ultrasonic treatment in a 500W ultrasonic instrument, and then performing centrifugal cleaning and drying to obtain an intercalation product;

thirdly, heating and expanding the intercalation product to obtain expanded boron powder;

and fourthly, stripping the expanded boron powder through a liquid phase to obtain the boron-alkene nanosheet. The specific process parameters are shown in Table 1.

The structure and performance of the boron alkene nanosheet obtained in the embodiment are characterized: the transverse dimension of the boron alkene nanometer is 5 μm and the thickness is 7nm through the transmission electron microscope and the atomic force microscope test, and the transmission electron microscope picture is shown in figure 1a, and the atomic force microscope picture is shown in figure 1 b. The specific performance parameters of the boron alkene nano-sheet are shown in the table 2.

Example 2

A preparation method of a borolene nano-sheet comprises the following steps:

firstly, adding a certain amount of boron powder into an isopropanol/DMF mixed solvent to prepare a dispersion liquid, and then carrying out water bath ultrasound by adopting an ultrasound instrument with the power of 500W, and keeping the temperature not to exceed 30 ℃ to obtain an ultrasound mixed liquid;

secondly, adding a product obtained by filtering the ultrasonic mixed solution into concentrated acid to form concentrated acid suspension, performing ultrasonic treatment in a 500W ultrasonic instrument, and then performing centrifugal cleaning and drying to obtain an intercalation product;

thirdly, heating and expanding the intercalation product to obtain expanded boron powder;

and fourthly, stripping the expanded boron powder through a liquid phase to obtain the boron-alkene nanosheet. The specific process parameters are shown in Table 1.

The structure and performance of the boron alkene nanosheet obtained in the embodiment are characterized: the transmission electron microscope and atomic force microscope tests prove that the nano-sized boron alkene has the transverse dimension of 3 mu m and the thickness of 4.5nm, and the transmission electron microscope picture is shown in figure 2a, and the atomic force microscope picture is shown in figure 2 b. The specific performance parameters of the boron alkene nano-sheet are shown in the table 2.

Example 3

A preparation method of a borolene nano-sheet comprises the following steps:

firstly, adding a certain amount of boron powder into isopropanol to prepare a dispersion liquid, and then carrying out water bath ultrasound by adopting an ultrasound instrument with the power of 500W, and keeping the temperature not to exceed 30 ℃ to obtain an ultrasonic mixed liquid;

secondly, adding a product obtained by filtering the ultrasonic mixed solution into concentrated acid to form concentrated acid suspension, performing ultrasonic treatment in a 500W ultrasonic instrument, and then performing centrifugal cleaning and drying to obtain an intercalation product;

thirdly, heating and expanding the intercalation product to obtain expanded boron powder;

and fourthly, stripping the expanded boron powder through a liquid phase to obtain the boron-alkene nanosheet. The specific process parameters are shown in Table 1.

The structure and performance of the boron alkene nanosheet obtained in the embodiment are characterized: the transverse dimension of the boron alkene nanometer is confirmed to be 2 μm and the thickness is confirmed to be 13nm through transmission electron microscope and atomic force microscope tests, and a transmission mirror image of the boron alkene nanometer is shown in figure 3a, and an atomic force microscope image of the boron alkene nanometer is shown in figure 3 b. The specific performance parameters of the boron alkene nano-sheet are shown in the table 2.

Example 4

A preparation method of a borolene nano-sheet comprises the following steps:

firstly, adding a certain amount of boron powder into NMP to prepare a dispersion liquid, and then carrying out water bath ultrasound by adopting an ultrasound instrument with the power of 500W, keeping the temperature not to exceed 30 ℃ to obtain an ultrasonic mixed liquid;

secondly, adding a product obtained by filtering the ultrasonic mixed solution into concentrated acid to form concentrated acid suspension, performing ultrasonic treatment in a 500W ultrasonic instrument, and then performing centrifugal cleaning and drying to obtain an intercalation product;

thirdly, heating and expanding the intercalation product to obtain expanded boron powder;

and fourthly, stripping the expanded boron powder through a liquid phase to obtain the boron-alkene nanosheet. The specific process parameters are shown in Table 1.

The structure and performance of the boron alkene nanosheet obtained in the embodiment are characterized: the transverse dimension of the boron alkene nanometer is 1 μm and the thickness is 4nm, which are confirmed by transmission electron microscope and atomic force microscope tests, and the transmission electron microscope picture is shown in figure 4a, and the atomic force microscope picture is shown in figure 4 b. The specific performance parameters of the boron alkene nano-sheet are shown in the table 2.

Example 5

A preparation method of a borolene nano-sheet comprises the following steps:

firstly, adding a certain amount of boron powder into a water/isopropanol mixed solvent to prepare a dispersion liquid, and then carrying out water bath ultrasound by adopting an ultrasonic instrument with the power of 500W, and keeping the temperature not to exceed 30 ℃ to obtain an ultrasonic mixed liquid;

secondly, adding a product obtained by filtering the ultrasonic mixed solution into concentrated acid to form concentrated acid suspension, performing ultrasonic treatment in a 500W ultrasonic instrument, and then performing centrifugal cleaning and drying to obtain an intercalation product;

thirdly, heating and expanding the intercalation product to obtain expanded boron powder;

and fourthly, stripping the expanded boron powder through a liquid phase to obtain the boron-alkene nanosheet. The specific process parameters are shown in Table 1.

The structure and performance of the boron alkene nanosheet obtained in the embodiment are characterized: the transmission electron microscope and atomic force microscope tests prove that the nano-sized boron alkene has the transverse dimension of 3.5 mu m and the thickness of 12nm, and the transmission electron microscope picture is shown in figure 5a, and the atomic force microscope picture is shown in figure 5 b. The specific performance parameters of the boron alkene nano-sheet are shown in the table 2.

Table 1 examples 1-5 borolene nanoplatelet preparation process parameters.

Table 2 examples 1-5 borolene nanoplatelet physico-chemical parameters

As can be seen from the above, the boron-containing olefin nanosheets prepared in the embodiments 1-5 have a typical two-dimensional layered structure, the thickness of the boron-containing olefin nanosheets is 4-13nm, the transverse dimension of the boron-containing olefin nanosheets is 1-5 microns, the content of boron is above 95%, the content of oxygen is above 0.7%, and the apparent density of the boron-containing olefin nanosheets is 0.06-0.3g/cm³In the research process of other embodiments, the invention discovers that the thickness of the boron-alkene nano-sheet obtained by the preparation method can reach 0.3nm-10 μm, and the transverse dimension can reach 10nm-100 μm. The boron alkene nanosheet obtained by the technical scheme of the invention has excellent performance, the preparation process is green and environment-friendly, the continuous industrial production can be realized, and the boron alkene nanosheet has wide application prospect.

It should be understood that the above describes only some embodiments of the present invention, and that various other changes and modifications can be made by one skilled in the art without departing from the inventive concept herein.