Method for preparing boronene by vacuum thermal decomposition
The vacuum thermal decomposition method for preparing borene solves the problems of complex preparation, high energy consumption, and pollution in existing technologies, and achieves low-cost and high-efficiency preparation of borene with high purity and uniform size, making it suitable for industrial applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN UNIV
- Filing Date
- 2024-03-01
- Publication Date
- 2026-06-09
AI Technical Summary
Existing methods for preparing borophene are complex, energy-intensive, costly, and prone to generating toxic and harmful gases and solid impurities, making industrial-scale production difficult.
Boronene was prepared by vacuum thermal decomposition, which included ball milling, tableting, vacuum thermal decomposition, solid-liquid separation, acidic solution washing and freeze drying. The temperature and pressure were controlled within a suitable range to avoid oxidation and impurity contamination.
It has achieved low-cost, high-efficiency, green and safe preparation of borones, with high product purity and uniform size, which is suitable for industrial applications.
Smart Images
Figure CN118026194B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of borophene materials technology, and in particular to a method for preparing borophene by vacuum thermal decomposition. Background Technology
[0002] Boroene is a novel two-dimensional material with unique properties, following graphene and boron nitride. Compared to graphene, boroene possesses advantages such as stronger metallicity, lighter weight, greater hardness, and better charge carrier transport, exhibiting superior physicochemical properties. From an energy storage perspective, boroene has efficient lithium, sodium, and potassium storage capabilities, meeting the development and application needs of high-energy and high-power-density supercapacitors and battery electrode materials.
[0003] However, borophene does not exist naturally and must be obtained through artificial synthesis. The numerous possible structures of borophene due to its electron-deficient structure increase the difficulty of its synthesis. Currently, the raw materials for borophene preparation are mostly elemental boron, boric acid, or borohydrides, and the main preparation methods include: liquid-phase ultrasonic exfoliation, a combination of oxidation etching and liquid-phase exfoliation, solvothermal nucleation and precipitation, thermal decomposition and reduction, vapor deposition, and molecular beam epitaxy. However, these methods suffer from problems such as complex processes, high energy consumption, high raw material costs, the risk of explosion during experiments, and the generation of toxic and harmful gases. Summary of the Invention
[0004] In view of this, this application provides a method for preparing borene by vacuum thermal decomposition and its application. This method has low preparation cost and high production efficiency. Moreover, the preparation method takes place in a closed space, without solid impurity pollution, and is green and safe. The borene obtained has high purity, high yield and uniform size.
[0005] The first aspect of this application provides a method for preparing boronene by vacuum thermal decomposition, characterized by comprising the following steps:
[0006] The bulk metal boride was ball-milled under an inert atmosphere to obtain metal boride powder.
[0007] The metal boride powder is compressed into tablets to obtain metal boride flakes;
[0008] The metal boride sheet was subjected to vacuum thermal decomposition in a vacuum reaction environment. The resulting product was mixed with water and then subjected to solid-liquid separation to obtain a solid.
[0009] The solid was washed with an acidic solution until neutral, and then freeze-dried to obtain boronene.
[0010] The metal borides include MgB2 and / or AlB2.
[0011] In this embodiment of the application, the particle size of the metal boride powder is 1μm-10μm, and the thickness of the metal boride sheet is 3mm-6mm.
[0012] In this embodiment of the application, the inert atmosphere is an argon atmosphere or a nitrogen atmosphere.
[0013] In this embodiment of the application, the ball milling time is 3h-6h, and the ball milling speed is 400r / min-600r / min.
[0014] In this embodiment of the application, the pressure of the tablet compression process is 5MPa-10MPa.
[0015] In this embodiment of the application, the creation of the vacuum reaction environment includes: repeating the "gas filling-vacuuming" operation on the vacuum pyrolysis equipment 3-5 times, and finally drawing the vacuum reaction environment.
[0016] In this embodiment of the application, the pressure of the vacuum thermal decomposition is 10 Pa to 100 Pa.
[0017] In this embodiment of the application, the vacuum thermal decomposition includes a heating process and a heat preservation process, wherein the heating rate of the heating process is 5℃ / min-20℃ / min.
[0018] In this embodiment, the vacuum pyrolysis equipment is a dual-temperature zone tubular furnace, which includes a high-temperature heating and volatilization zone and a low-temperature condensation zone. The heat preservation treatment in the high-temperature heating and volatilization zone has a heat preservation temperature of 800℃-1100℃ and a heat preservation time of 0.5h-3h. The heat preservation treatment in the low-temperature condensation zone has a heat preservation temperature of 300℃-600℃ and a heat preservation time of 3h-6h.
[0019] In this embodiment, the acidic solution includes hydrochloric acid and / or sulfuric acid, and the concentration of the acidic solution is 1 mol / L to 3 mol / L.
[0020] In this embodiment of the application, the washing process includes a heating and stirring process, wherein the stirring speed of the heating and stirring process is 400 r / min-600 r / min, and the heating and stirring process takes 2 h-4 h.
[0021] In this embodiment of the application, the freeze-drying time is 12h-48h.
[0022] The second aspect of this application provides a method for preparing borene by vacuum thermal decomposition provided in the first aspect of this application.
[0023] In this embodiment of the application, the borene has a two-dimensional sheet structure, the thickness of the borene is 4nm-7nm, and the lateral dimension of the borene is 250nm-4000nm. Attached Figure Description
[0024] Figure 1 A flowchart of a method for preparing boronene by vacuum thermal decomposition according to an embodiment of this application;
[0025] Figure 2 This is a field emission scanning electron microscope (SEM) characterization image of the borophene prepared in Example 1 of this application;
[0026] Figure 3 The X-ray diffraction (XRD) pattern of borone obtained in Example 1 of this application is shown.
[0027] Figure 4 This is an atomic force microscope (AFM) characterization image of the borophene prepared in Example 1 of this application;
[0028] Figure 5 This is a laser particle size distribution diagram of the boronene prepared in Example 1 of this application. Detailed Implementation
[0029] The present application will be further described in detail below with reference to preferred embodiments, but the scope of protection of the present application is not limited to the following specific embodiments.
[0030] In this application, all technical terms have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this application.
[0031] Boroene is a novel two-dimensional material with unique properties, following graphene and boron nitride. Compared to graphene, boroene possesses advantages such as stronger metallicity, lighter weight, greater hardness, and better charge carrier transport, exhibiting superior physicochemical properties. From an energy storage perspective, boroene has efficient lithium, sodium, and potassium storage capabilities, meeting the development and application needs of high-energy and high-power-density supercapacitors and battery electrode materials.
[0032] However, borene does not exist in nature and needs to be obtained through artificial synthesis. However, due to its electron-deficient structure, borene has many structures, which increases the difficulty of its synthesis. At present, the raw materials for the preparation of borene are mostly elemental boron, boric acid, or borohydride, and the main preparation methods include the following: (1) preparation of borene by liquid phase ultrasonic exfoliation technology. The exfoliation process of this method is complicated, the reagent cost is high and it is easy to volatilize, and there is a large amount of secondary waste liquid that is difficult to treat; (2) preparation of borene by combination of oxidation etching and liquid phase exfoliation technology. This method is relatively complicated, the energy consumption during the preparation process is high and it is easy to generate toxic and harmful gases; (3) preparation of borene by solvothermal nucleation and precipitation technology. This method has problems such as complicated process, easy explosion, high energy consumption, and easy generation of toxic and harmful gases; (4) preparation of borene by Ar / H2 thermal decomposition and reduction technology. The raw materials of this method are easy to decompose and the equipment precision requirements are high; (5) preparation of borene by vapor phase deposition and molecular beam epitaxy technology. This method has high experimental temperature, high cost of supporting equipment and low yield, resulting in high production cost and making it impossible to popularize industrial production.
[0033] To address the aforementioned issues, this application provides a method for preparing borene by vacuum thermal decomposition and its application. This method involves low vacuum thermal decomposition temperature, low preparation cost, and high production efficiency. Furthermore, the preparation occurs in a closed vacuum environment, eliminating secondary oxidation of raw materials and products, preventing solid impurity contamination, and ensuring green and safe production. The resulting borene exhibits high purity, high yield, and uniform size.
[0034] This application provides a method for preparing boronene by vacuum thermal decomposition. Figure 1 The flowchart of this method includes the following steps:
[0035] S101. The metal boride bulk is ball-milled under an inert atmosphere to obtain metal boride powder;
[0036] S102. The metal boride powder is compressed into tablets to obtain metal boride flakes.
[0037] S103. The metal boride sheet is subjected to vacuum thermal decomposition in a vacuum reaction environment. The obtained product is mixed with water and then subjected to solid-liquid separation to obtain a solid.
[0038] S104. The solid is washed with an acidic solution until neutral, and then freeze-dried to obtain boronene.
[0039] In some embodiments of this application, the metal boride includes MgB2 and / or AlB2. In some embodiments of this application, the metal boride is MgB2. In other embodiments of this application, the metal boride is AlB2. In still other embodiments of this application, the metal boride is both MgB2 and AlB2.
[0040] In step S101, the inert atmosphere is an argon atmosphere or a nitrogen atmosphere. In some embodiments of this application, the inert atmosphere may be, for example, an argon atmosphere.
[0041] In this application, the ball milling time is 3-6 hours. In some specific embodiments, the ball milling time can be, for example, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours. In this application, the ball milling speed is 400 r / min-600 r / min. In some specific embodiments, the ball milling speed can be, for example, 400 r / min, 420 r / min, 450 r / min, 480 r / min, 500 r / min, 520 r / min, 550 r / min, 580 r / min, or 600 r / min. By controlling the ball milling time and speed within a suitable range, this application ensures that the metal boride agglomerates are fully pulverized, resulting in metal boride powder with uniform particles and a suitable particle size, facilitating further tableting of the metal boride powder.
[0042] In this application, the ball-to-material ratio for ball milling is (50-200):1. In some specific embodiments of this application, the ball-to-material ratio for ball milling can be, for example, 50:1, 80:1, 100:1, 120:1, 150:1, 180:1, or 200:1. In this application, the milling balls used in the ball milling process include, but are not limited to, ZrO2 milling balls. By controlling the ball-to-material ratio within a suitable range, this application can achieve a more uniform size of the metal boride powder obtained through ball milling.
[0043] In this application, the particle size of the metal boride powder is 1 μm-10 μm. In some embodiments of this application, the particle size of the metal boride powder can be, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. This application obtains ultrafine metal boride powder with a particle size of less than 10 μm by ball milling the metal boride bulk, which facilitates subsequent tableting processing to obtain more uniformly distributed metal boride flakes.
[0044] In step S102, the pressure of the tableting process is 5 MPa-10 MPa. In some specific embodiments of this application, the pressure of the tableting process can be, for example, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, or 10 MPa. By controlling the pressure within a suitable range, metal boride flakes with a suitable thickness range can be obtained. This application uses tableting to compress metal boride powder into metal boride flakes with a suitable thickness range, thereby facilitating subsequent vacuum thermal decomposition of the metal boride flakes. Compressing metal boride powder into metal boride flakes can effectively prevent the metal boride from being extracted, and can also effectively avoid the poor thermal conductivity and incomplete reaction caused by the static electricity between ultrafine metal boride powder particles, which prevents the formation of a tight contact interface between particles.
[0045] In this application, the thickness of the metal boride sheet is 3mm-6mm. In some specific embodiments of this application, the thickness of the metal boride sheet can be, for example, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, or 6mm. Controlling the thickness of the metal boride sheet within a suitable range can further facilitate the subsequent vacuum thermal decomposition of the metal boride and effectively avoid phenomena such as incomplete reaction.
[0046] In step S103, creating the vacuum reaction environment includes repeatedly performing a "gas filling-vacuuming" operation on the vacuum pyrolysis equipment. In this embodiment, the "gas filling-vacuuming" operation is repeated 3-5 times. In some specific embodiments, the "gas filling-vacuuming" operation can be repeated, for example, 3, 4, or 5 times. In this embodiment, the purpose of repeatedly performing the "gas filling-vacuuming" operation is to eventually achieve a vacuum reaction environment. In this embodiment, the pressure of the vacuum reaction environment is 10 Pa-100 Pa. In some specific embodiments, the pressure of vacuum pyrolysis can be, for example, 10 Pa, 20 Pa, 30 Pa, 40 Pa, 50 Pa, 60 Pa, 70 Pa, 80 Pa, 90 Pa, or 100 Pa.
[0047] In this application's embodiments, the "gas filling" operation in the "gas filling-vacuuming" process includes: introducing an inert atmosphere to purge air. In some embodiments, the inert atmosphere may be, for example, an argon atmosphere or a nitrogen atmosphere. This application purges the air in the reaction equipment and thus removes O2 by repeatedly introducing an inert atmosphere, resulting in better reaction conditions. This effectively avoids the problem of secondary oxidation of raw materials and products introducing new impurities that lead to a decrease in product purity, resulting in a clean and pollution-free final product, boronene.
[0048] In this application, the pressure of vacuum thermal decomposition is 10 Pa to 100 Pa. In some specific embodiments of this application, the pressure of vacuum thermal decomposition can be, for example, 10 Pa, 20 Pa, 30 Pa, 40 Pa, 50 Pa, 60 Pa, 70 Pa, 80 Pa, 90 Pa, or 100 Pa.
[0049] In this application, vacuum thermal decomposition includes a heating process and a holding process. The heating rate of the heating process is 5°C / min to 20°C / min. In some specific embodiments, the heating rate of the heating process can be, for example, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, 11°C / min, 12°C / min, 13°C / min, 14°C / min, 15°C / min, 16°C / min, 18°C / min, or 20°C / min. In some embodiments of this application, the heating rate of the heating process can be 10°C / min to 15°C / min.
[0050] In this embodiment, the equipment for vacuum pyrolysis is a dual-temperature zone tube furnace, which includes a high-temperature heating volatilization zone and a low-temperature condensation zone. This application utilizes a dual-temperature zone tube furnace to perform vacuum pyrolysis on metal boride sheets. Elemental Mg and / or Al volatilize and condense in the low-temperature condensation zone as vapor, while B remains as a solid in the high-temperature heating volatilization zone, thereby separating the elemental metals and B to obtain the vacuum pyrolysis products.
[0051] In this embodiment, the heat preservation treatment in the high-temperature heating and volatilization zone is at a temperature of 800℃-1100℃, and the heat preservation time is 0.5h-3h. In some embodiments of this application, the heat preservation temperature in the high-temperature heating and volatilization zone can be, for example, 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, or 1100℃, and the heat preservation time can be, for example, 0.5h, 1h, 1.5h, 2h, 2.5h, or 3h.
[0052] In this embodiment, the heat preservation treatment in the low-temperature condensation zone is at a temperature of 300℃-600℃, and the heat preservation time is 3h-6h. In some embodiments of this application, the heat preservation temperature in the low-temperature condensation zone can be, for example, 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, or 600℃, and the heat preservation time can be, for example, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, or 6h. MgB2 and AlB2 are both ionic compounds with a hexagonal crystal system. They are intercalated compounds, i.e., metal layers and B layers are arranged alternately. The melting point of Mg metal is 648℃, and the melting point of Al metal is 660℃. Compared with other metals with higher melting points, Mg and Al metals are more easily distilled and volatilized under high-temperature vacuum conditions. This application, by controlling the holding temperature and holding time in the high-temperature heating volatilization zone and the low-temperature condensation zone within a suitable range, allows MgB2 and AlB2 to undergo sufficient vacuum thermal decomposition. Mg and Al volatilize as vapor under high-temperature conditions and condense in the low-temperature condensation zone, while B remains as a solid in the high-temperature heating volatilization zone. This ensures complete separation of the metal and B, further improving the efficiency and purity of borophene preparation. Furthermore, compared to other conventional borophene preparation methods, vacuum thermal decomposition involves a lower temperature, resulting in greater energy savings, further reducing preparation costs and improving the safety of the preparation process.
[0053] In some embodiments of this application, the temperature in the high-temperature heating and volatilization zone can be 800℃-1000℃, and the holding time can be 1h-2h; when the temperature in the low-temperature condensation zone is 300℃-400℃, the holding time is preferably 3h-4h. In some embodiments of this application, the temperature in the high-temperature heating and volatilization zone can be 1000℃-1100℃, and the holding time can be 2h-3h; when the temperature in the low-temperature condensation zone is 400℃-600℃, the holding time is preferably 5h-6h.
[0054] In this application's embodiments, the process after vacuum pyrolysis also includes a furnace cooling process to room temperature. In some embodiments of this application, the pressure maintained during the furnace cooling process to room temperature is the same as the pressure during vacuum pyrolysis.
[0055] In this embodiment, the vacuum pyrolysis product is mixed with water and then subjected to solid-liquid separation. The surface of product B obtained after vacuum pyrolysis retains some incompletely separated Mg or Al. Mixing the product with water passivates the metal residue on the surface of B, thereby obtaining solid B and Mg(OH)2 and Al(OH)3. In this embodiment, the number of times the product is mixed with water and the amount of water used for solid-liquid separation are not particularly limited, until the vacuum pyrolysis product is completely dissolved and precipitated. In some embodiments of this application, the number of times the product is mixed with water and the number of times solid-liquid separation is performed can be 1-3 times. In some specific embodiments, for example, it can be 1 time, 2 times, or 3 times. In this embodiment, the solid-liquid separation method includes, but is not limited to, commonly used solid-liquid separation methods in the art, such as filtration or centrifugation.
[0056] In step S104, the acidic solution includes hydrochloric acid and / or sulfuric acid, and the concentration of the acidic solution is 1 mol / L-3 mol / L. In some embodiments of this application, the concentration of the acidic solution can be, for example, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, or 3 mol / L. Adding the solid after solid-liquid separation to the acidic solution for washing allows Mg(OH)2 and Al(OH)3 to undergo a passivation reaction, thereby removing impurities Mg(OH)2 and Al(OH)3 from the solid, resulting in clean boronene powder, thus achieving the purpose of impurity removal.
[0057] In this application, the number of acidic solution washing treatments and the amount of acid used are not particularly limited, until the solution is neutral, i.e., the impurities Mg(OH)2 and Al(OH)3 are completely removed. In some embodiments of this application, the number of acidic solution washing treatments can be 3-5 times. In some specific embodiments, for example, it can be 3, 4, or 5 times.
[0058] In this application embodiment, the washing process includes a heating and stirring process. In this application embodiment, the stirring speed of the heating and stirring process is 300 r / min-600 r / min, and the heating and stirring time is 2 h-4 h. In some specific embodiments of this application, the stirring speed of the heating and stirring process can be, for example, 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, 550 r / min, or 600 r / min, and the heating and stirring time can be, for example, 2 h, 2.5 h, 3 h, 3.5 h, or 4 h. In this application embodiment, the temperature of the heating and stirring process is 25℃-40℃. In some specific embodiments, the temperature of the heating and stirring process can be, for example, 25℃, 28℃, 30℃, 32℃, 33℃, 35℃, 36℃, 38℃, or 40℃. By controlling the washing process parameters within the above-mentioned suitable ranges, Mg(OH)2 and Al(OH)3 impurities can be removed as much as possible.
[0059] In this application, the freeze-drying time is 12h-48h. In some embodiments of this application, the freeze-drying time may be, for example, 12h, 15h, 18h, 20h, 24h, 25h, 30h, 35h, 36h, 40h, 42h, 45h, or 48h.
[0060] The method for preparing borene by vacuum thermal decomposition provided in this application has the advantages of low vacuum thermal decomposition temperature, low preparation cost, high production efficiency, and the preparation method is carried out in a closed vacuum environment, which eliminates the problem of secondary oxidation of raw materials and products, avoids solid impurity pollution, is green and safe, and produces borene with high purity.
[0061] This application also provides a method for preparing borene using vacuum thermal decomposition as described above. In the embodiments of this application, the borene has a two-dimensional sheet structure with a thickness of 4 nm-7 nm and a lateral dimension of 250 nm-4000 nm. In some specific embodiments of this application, the thickness of the borene can be, for example, 4 nm, 5 nm, 6 nm, or 7 nm, and the lateral dimension can be, for example, 250 nm, 300 nm, 400 nm, 500 nm, 600 nm, 800 nm, 1000 nm, 1500 nm, 2000 nm, 2500 nm, 3000 nm, 3500 nm, or 4000 nm. The borene prepared by vacuum thermal decomposition has high purity, high yield, and uniform size. The borene prepared by the vacuum thermal decomposition method provided in this application can be used in capacitors, battery electrode materials, and other fields.
[0062] The present application will be further described below with reference to several embodiments:
[0063] Example 1
[0064] MgB2 bulk material was mechanically ball-milled under an argon atmosphere for 4 hours at a speed of 500 r / min to obtain MgB2 powder with a particle size of 1 μm-5 μm. 1 g of the MgB2 powder was then compressed into tablets at a pressure of 6 MPa to obtain MgB2 flakes with a thickness of 3 mm. A dual-temperature zone tube furnace was purged with argon gas and then evacuated three times to obtain a vacuum reaction environment with a pressure of 10 Pa. The resulting MgB2 flakes were then placed in the dual-temperature zone tube furnace for vacuum pyrolysis at a heating rate of [missing information]. The furnace was heated at 5℃ / min, with the high-temperature evaporation zone at 800℃ for 3 hours and the low-temperature condensation zone at 300℃ for 6 hours. After the condensation period, the vacuum pump continued to run until the furnace temperature dropped to room temperature. The vacuum pump was then turned off, the product was removed, placed in an aqueous solution, filtered, and a mixed solid was obtained. This mixed solid was then added to 1 mol / L dilute hydrochloric acid, heated and stirred (40℃ for 4 hours at 300 r / min), washed, filtered, and freeze-dried for 12 hours to obtain boronene. The obtained boronene was characterized by field emission scanning electron microscopy, X-ray diffraction, atomic force microscopy, and laser particle size analysis. The results are shown below. Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown. From Figure 2-5 As can be seen, this application prepared uniform two-dimensional boronene nanosheets with lateral dimensions of 250 nm-4000 nm by vacuum thermal decomposition.
[0065] Example 2
[0066] MgB2 bulk material was mechanically ball-milled under an argon atmosphere for 4 hours at a speed of 500 r / min to obtain MgB2 powder with a particle size of 1 μm-5 μm. 1 g of the MgB2 powder was then compressed into tablets at a pressure of 6 MPa to obtain MgB2 flakes with a thickness of 3 mm. A dual-temperature zone tube furnace was purged with argon gas and then evacuated three times to obtain a vacuum reaction environment with a pressure of 10 Pa. The resulting MgB2 flakes were then placed in the dual-temperature zone tube furnace for vacuum pyrolysis at a heating rate of [missing information]. The temperature of the high-temperature evaporation zone was 900℃ for 3 hours, and the temperature of the low-temperature condensation zone was 400℃ for 6 hours. After the holding time was completed, the vacuum pump continued to run until the furnace temperature dropped to room temperature. The vacuum pump was then turned off, the product was removed, placed in an aqueous solution, filtered, and a mixed solid was obtained. The mixed solid was then added to a 1 mol / L dilute hydrochloric acid solution, heated and stirred (temperature 40℃, time 4 hours, speed 300 r / min), washed, filtered, and freeze-dried for 12 hours to obtain boronene.
[0067] Example 3
[0068] MgB2 bulk material was mechanically ball-milled under an argon atmosphere for 4 hours at a speed of 500 r / min to obtain MgB2 powder with a particle size of 1 μm-5 μm. 1 g of the MgB2 powder was then compressed into tablets at a pressure of 6 MPa to obtain MgB2 flakes with a thickness of 3 mm. A dual-temperature zone tube furnace was purged with argon gas and then evacuated three times to obtain a vacuum reaction environment with a pressure of 10 Pa. The resulting MgB2 flakes were then placed in the dual-temperature zone tube furnace for vacuum pyrolysis at a heating rate of [missing information]. The temperature of the high-temperature evaporation zone was 1000℃ for 3 hours, and the temperature of the low-temperature condensation zone was 500℃ for 6 hours. After the holding time, the vacuum pump continued to run until the furnace temperature dropped to room temperature. The vacuum pump was then turned off, the product was removed, placed in an aqueous solution, filtered, and a mixed solid was obtained. The mixed solid was then added to a 1 mol / L dilute hydrochloric acid solution, heated and stirred (temperature 40℃, time 4 hours, speed 300 r / min), washed, filtered, and freeze-dried for 12 hours to obtain boronene.
[0069] Example 4
[0070] MgB2 bulk material was mechanically ball-milled under an argon atmosphere for 4 hours at a speed of 500 r / min to obtain MgB2 powder with a particle size of 1 μm-5 μm. 1 g of the MgB2 powder was then compressed into tablets at a pressure of 6 MPa to obtain MgB2 flakes with a thickness of 3 mm. A dual-temperature zone tube furnace was purged with argon gas and then evacuated three times to obtain a vacuum reaction environment with a pressure of 10 Pa. The resulting MgB2 flakes were then placed in the dual-temperature zone tube furnace for vacuum pyrolysis at a heating rate of [missing information]. The temperature of the high-temperature evaporation zone was 1100℃ for 3 hours, and the temperature of the low-temperature condensation zone was 600℃ for 6 hours. After the holding time was completed, the vacuum pump continued to run until the furnace temperature dropped to room temperature. The vacuum pump was then turned off, the product was removed, placed in an aqueous solution, filtered, and a mixed solid was obtained. The mixed solid was then added to a 1 mol / L dilute hydrochloric acid solution, heated and stirred (temperature 40℃, time 4 hours, speed 300 r / min), washed, filtered, and freeze-dried for 12 hours to obtain boronene.
[0071] Example 5
[0072] MgB2 bulk material was mechanically ball-milled under an argon atmosphere for 4 hours at a speed of 500 r / min to obtain MgB2 powder with a particle size of 1 μm-5 μm. 1 g of the MgB2 powder was then compressed into tablets at a pressure of 6 MPa to obtain MgB2 flakes with a thickness of 3 mm. A dual-temperature zone tube furnace was purged with argon gas and then evacuated three times to obtain a vacuum reaction environment at a pressure of 100 Pa. The resulting MgB2 flakes were then placed in the dual-temperature zone tube furnace for vacuum pyrolysis, with a heating rate of... The heating speed was 5℃ / min. The temperature of the high-temperature evaporation zone was 900℃, and the holding time was 3h. The temperature of the low-temperature condensation zone was 400℃, and the holding time was 6h. After the holding time was completed, the vacuum pump continued to run until the furnace temperature dropped to room temperature. The vacuum pump was then turned off, the product was taken out, placed in an aqueous solution, filtered, and a mixed solid was obtained. The mixed solid was then added to a 1mol / L dilute hydrochloric acid solution, heated and stirred (temperature 40℃, time 4h, speed 300r / min), washed, filtered, and freeze-dried for 12h to obtain boronene.
[0073] Example 6
[0074] MgB2 bulk material was mechanically ball-milled under an argon atmosphere for 4 hours at a speed of 500 r / min to obtain MgB2 powder with a particle size of 1 μm-5 μm. 1 g of the MgB2 powder was then compressed into tablets at a pressure of 6 MPa to obtain MgB2 flakes with a thickness of 6 mm. A dual-temperature zone tube furnace was purged with argon gas and then evacuated three times to obtain a vacuum reaction environment with a pressure of 10 Pa. The resulting MgB2 flakes were then placed in the dual-temperature zone tube furnace for vacuum pyrolysis at a heating rate of [missing information]. The temperature of the high-temperature evaporation zone was 900℃ for 3 hours, and the temperature of the low-temperature condensation zone was 400℃ for 6 hours. After the holding time was completed, the vacuum pump continued to run until the furnace temperature dropped to room temperature. The vacuum pump was then turned off, the product was removed, placed in an aqueous solution, filtered, and a mixed solid was obtained. The mixed solid was then added to a 1 mol / L dilute hydrochloric acid solution, heated and stirred (temperature 40℃, time 4 hours, speed 300 r / min), washed, filtered, and freeze-dried for 12 hours to obtain boronene.
[0075] Example 7
[0076] AlB2 bulk material was mechanically ball-milled under an argon atmosphere for 4 hours at a speed of 500 r / min to obtain AlB2 powder with a particle size of 1 μm-5 μm. 1 g of AlB2 powder was then compressed into tablets at a pressure of 6 MPa to obtain AlB2 flakes with a thickness of 3 mm. A dual-temperature zone tube furnace was purged with argon gas and then evacuated three times to obtain a vacuum reaction environment with a pressure of 10 Pa. The prepared AlB2 flakes were then placed in the dual-temperature zone tube furnace for vacuum pyrolysis at a heating rate of [missing information]. The temperature of the high-temperature evaporation zone was 900℃ for 3 hours, and the temperature of the low-temperature condensation zone was 400℃ for 6 hours. After the holding time was completed, the vacuum pump continued to run until the furnace temperature dropped to room temperature. The vacuum pump was then turned off, the product was removed, placed in an aqueous solution, filtered, and a mixed solid was obtained. The mixed solid was then added to a 1 mol / L dilute hydrochloric acid solution, heated and stirred (temperature 40℃, time 4 hours, speed 300 r / min), washed, filtered, and freeze-dried for 12 hours to obtain boronene.
[0077] The preferred embodiments have been described in detail above, but the present invention is not limited to the specific implementation methods described above. Those skilled in the art can make various specific modifications under the guidance of this application without departing from the scope of protection of this application, and these modifications all fall within the scope of protection of the present invention.
Claims
1. A method for preparing boronene by vacuum thermal decomposition, characterized in that, Includes the following steps: The bulk metal boride was ball-milled under an inert atmosphere to obtain metal boride powder. The metal boride powder is compressed into tablets to obtain metal boride flakes; The metal boride sheet was subjected to vacuum thermal decomposition in a vacuum reaction environment. The resulting product was mixed with water and then subjected to solid-liquid separation to obtain a solid. The solid was washed with an acidic solution until neutral, and then freeze-dried to obtain boronene. The metal borides include MgB2 and / or AlB2.
2. The method for preparing boronene by vacuum thermal decomposition as described in claim 1, characterized in that, The particle size of the metal boride powder is 1 μm-10 μm, and the thickness of the metal boride sheet is 3 mm-6 mm.
3. The method for preparing boronene by vacuum thermal decomposition as described in claim 1, characterized in that, The inert atmosphere is an argon atmosphere or a nitrogen atmosphere; the ball milling time is 3 h-6 h, and the ball milling speed is 400 r / min-600 r / min.
4. The method for preparing boronene by vacuum thermal decomposition as described in claim 1, characterized in that, The pressure for tablet compression is 5 MPa-10 MPa.
5. The method for preparing borone by vacuum thermal decomposition as described in claim 1, characterized in that, The creation of the vacuum reaction environment includes: repeating the "gas filling-vacuuming" operation on the vacuum pyrolysis equipment 3-5 times until the vacuum reaction environment is reached, and the pressure of the vacuum reaction environment is 10 Pa-100 Pa.
6. The method for preparing boronene by vacuum thermal decomposition as described in claim 1, characterized in that, The pressure of the vacuum pyrolysis is 10 Pa to 100 Pa.
7. The method for preparing borone by vacuum thermal decomposition as described in claim 1, characterized in that, The vacuum pyrolysis includes a heating process and a holding process. The heating rate of the heating process is 5℃ / min-20℃ / min. The equipment for the vacuum pyrolysis is a dual-temperature zone tube furnace, which includes a high-temperature heating and volatilization zone and a low-temperature condensation zone. The holding temperature in the high-temperature heating and volatilization zone is 800℃-1100℃, and the holding time is 0.5 h-3 h. The holding temperature in the low-temperature condensation zone is 300℃-600℃, and the holding time is 3 h-6 h.
8. The method for preparing boronene by vacuum thermal decomposition as described in claim 1, characterized in that, The acidic solution includes hydrochloric acid and / or sulfuric acid, and the concentration of the acidic solution is 1 mol / L-3 mol / L; the washing treatment includes heating and stirring treatment, the stirring speed of the heating and stirring treatment is 400 r / min-600 r / min, and the heating and stirring treatment time is 2 h-4 h; the freeze-drying time is 12 h-48 h.