CN1328158C - Prepn process of nanometer BN and B-C-N capsule or nanometer fullerene-like particle - Google Patents

Abstract

A method for preparing BN and BCN nanocapsules or fullerene-like nanoparticles, using nitrogen-containing gas or solid as a nitrogen source, using carbon-containing gas or solid as a carbon source, and using a nano-catalyst containing 20-70% boron "Alloy particles or simple boron as a boron source react at 600-900°C (in a tube furnace) or under microwave plasma excitation (in a quartz tube) to grow BN nanoparticles, BN nanocapsules or BN nanocapsules in a controlled manner and BN-like fullerene nanoparticles (if the carbon source is introduced into the BCN system), the latter two products are post-treated to further generate the corresponding pure BN-like fullerene nanoparticles (BCN-like fullerene nanoparticles Particle); The present invention has developed a new method for preparing high-purity fullerene-like nanoparticles. A variety of BN and BCN hollow nanostructures were prepared by this method.

Description

Preparation method of boron nitride and boron-carbon-nitrogen nanocapsules or fullerene-like nanoparticles

technical field

The invention relates to a new synthesis method for preparing novel nanostructures such as BN and B-C-N fullerene nanoparticles and intermediate products such as BN and B-C-N nanocapsules.

Background technique

Since the discovery of C60, carbon nanostructures (including fullerenes, nanotubes, nanowires, nanospheres, nanocapsules, etc.) have aroused widespread interest and attention due to their great scientific value and potential application prospects. Both theoretical and experimental studies have shown that carbon nanostructures have a series of excellent properties, such as good chemical and thermal stability, high mechanical strength, specific electrical properties and excellent field emission characteristics. At present, people have developed a variety of technical routes to synthesize such nanostructures, such as arc discharge method, laser evaporation method and thermal chemical vapor deposition method.

The discovery of a series of important carbon nanostructures and properties has stimulated people's interest in exploring new systems. Hexagonal boron nitride (h-BN) has a similar layer structure to graphite. Similarly, a series of novel BN nanostructures including BN-like fullerene nanoparticles and BN nanocapsules have also been discovered. h-BN and B-C-N are semiconductor materials with excellent physical and chemical properties, such as high temperature resistance, oxidation resistance, chemical corrosion resistance, good thermal conductivity, wave transparency and high dielectric properties, but also a performance Excellent field emission material. Compared with carbon nanostructures, nanostructures formed by h-BN and B-C-N (an analogue of carbon nanostructures) exhibit stronger high temperature resistance and oxidation resistance, and can provide an inert protective layer for other nanostructures wrapped by them. . As a kind of hollow nanoparticles, BN and B-C-N fullerene nanoparticles have the characteristics of large surface ratio, small particle size, and special mechanical properties. They have application prospects in the fields of catalysis, hydrogen absorption, and solid lubrication. The BN and B-C-N nanocapsules wrapped with magnetic substances such as Fe are nano-magnetic materials with an inert protective layer. Therefore, BN and B-C-N fullerenes and nanocapsules are a class of new materials with important scientific value and wide application prospects.

Existing BN nanostructure synthesis techniques include arc discharge method (N.G.Chopra, et al.Science 269 (1995) 966), laser evaporation (D.Bolberg et al.Appl.Phys.Lett.69 (1996) 2045), Carbon nanotube substitution method (W.Han et al.Appl.Phys.Lett.73(1998)3085) and thermal chemical vapor deposition method (Fan S.Set al.Mater.Lett.51, 31 5(2001)), etc. .

In the synthesis of nanostructures, chemical vapor deposition has been widely used due to its advantages of simple process and low cost; plasma-enhanced vapor deposition has the characteristics of low temperature and high activity, and it is also a nanomaterial preparation method with specific advantages . At present, some literatures and patents have been reported for the technology and method of synthesizing BN nanomaterials by methods such as vapor deposition. We used plasma-enhanced chemical vapor deposition to prepare BN nanotube arrays with B ₂ H ₆ and N ₂ /NH ₃ as B source and N source, and alumina as a template (Chinese patent application number: ZL 01113556.5); Using FeB, NiB, and CoB nano-amorphous as precursors, various BN nanostructures were prepared at about 1100°C (Chinese patent. Publication number: CN 1397491A). With the participation of Zn and other metals, Qian Yitai et al prepared BN nanotubes and BN hollow structures by solvothermal reaction of NH ₄ BF ₄ and KBH ₄ under high pressure (YTQian et.al. CHL 381, 1-2, pp. 74-79); BCl ₃ and NaNH ₃ were reacted under an inert atmosphere at room temperature to prepare a hollow structure composed of amorphous BN (YTQian et.al.Solid State Communications 130(2004) 537-540). Y. Bando et al. used BNO as a precursor to react at 1750°C under an argon flow containing a small amount of ammonia to prepare a BN hollow structure with a diameter of 30-200nm (Chem.Eur.J.2004, 10, 3667-3672) .

CN1397491A is the previous work of the applicant. The nanostructure of BN has a mixed shape, including fullerene-like nanoparticles, nanotubes, and nanowires, which are difficult to separate and affect the application prospects of this type of material.

Contents of the invention

The purpose of the present invention is to provide a method or process for preparing BN and B-C-N type fullerene nanoparticles. The purpose of the present invention is also to obtain BN and B-C-N nanocapsules and fullerene-like nanoparticles with different particle sizes and wall thicknesses by controlling process conditions, reaction time, boron-containing catalyst particle size and boron content.

The whole process of the present invention is realized in two steps. First, an intermediate product containing BN and/or B-C-N nanocapsules is synthesized, and then complete or open BN and/or B-C-N fullerene nanoparticles are obtained through post-processing. Specifically, pre-prepared boron-containing solid-phase precursors, including boron-containing "catalyst" alloys or simple boron nanoparticles, such as Fe-B, Ni-B, Co-B, Fe-Ni-B, Fe-Co- B, Ni-Co-B, B simple substance, etc. In the first step of the reaction, boron-containing particles are reacted with nitrogen-containing (optionally partially carbon-containing) mixed gas to form nanocapsules with a core-shell structure (Core-Shell Structure). wait. This reaction can be accomplished by applying two methods: a. Chemical Vapor Deposition (CVD), b. Plasma Chemical Vapor Deposition (MWCVD). In the second step reaction is the enucleation process of the encapsulated structure. It can also be done in two ways: 1. High temperature roasting, 2. Pickling. Through the above two steps, BN and/or B-C-N fullerene nanoparticles can be obtained. In summary: the present invention uses nitrogen-containing gas or solid as the nitrogen source, and nano-catalyst alloy particles containing 20-70% boron or simple boron as the boron source. The reaction takes place for 1-5 hours under the controllable growth of BN nanocapsules, or the mixture of BN nanocapsules and fullerene-like nanoparticles; at the same time, under the condition that carbon-containing gas or solid is the carbon source, B-C-N nanocapsules or Hybrid of B-C-N nanocapsules with fullerene-like nanoparticles. The present invention is the extended VLS reaction mechanism (Q.Wu, Z.Hu et al., J.Mater.Chem.13 (2003) 2024 that we propose; K.F.Huo, Z.Hu et al., J.Phys.Chem. B 107(2003)11316; K.F.Huo, Z.Hu et al., Appl.Phys.Lett.80(2002)3611; J.J.Fu, ..., Z.Hu et al., Nanotechnology 15(2004)727) Practical application in nanoparticles: The N atoms in the gas phase precursor NH3/N2 react chemically with the B atoms from the Fe-B nano "catalyst" in the "catalyst" droplet, when the generated BN species is in the "catalyst" "When the droplet reaches supersaturation, it will precipitate on its surface, forming BN nanocapsules in the form of wrapping. The intermediate product containing BN nanocapsules is calcined at high temperature (1400°C), and its core is released from the shell to form BN-like fullerene nanoparticles; in another denuclearization method, the core containing the metal catalyst is dissolved in an acid solution, The remaining shell forms the hollow BN-like fullerene nanoparticles. The formation mechanism of B-C-N type fullerene nanoparticles is the same, and the carbon-containing gas phase or other raw materials can be added to the raw materials.

The main difference between the present invention and the existing fullerene-like nanoparticle synthesis method is that the hollow fullerene-like nanostructure is synthesized through the two steps of "form the shell first, and then remove the core", so that simple fullerene-like nanostructures can be prepared. fullerene nanoparticles, and control the product morphology by adjusting the particle size of the raw materials and reaction conditions.

The details of the inventive method are:

1. The device required by the present invention mainly consists of three parts: furnace body, gas distribution system and vacuum system. The relationship and function of each part are as follows: (1) The reaction chamber made of corundum tube or stainless steel tube is placed in the tube furnace Inside, a quartz boat with a boron-containing catalyst is placed in the center of the reaction chamber, and the temperature of the growth zone can be adjusted to facilitate the growth of BN and B-C-N nanostructures. (2) The gas distribution system is composed of a gas circuit and a mass flow meter, which is connected to one end of the growth chamber. It can be used to adjust the type, flow rate and ratio of the BN and B-C-N nanostructure growth chamber gases. (3) Vacuum system, which can be used to repeatedly fill argon and vacuumize the growth chamber before the temperature rises, eliminating the possibility that the boron-containing nanoparticles in the growth chamber will be oxidized at high temperature, and can also adjust the vacuum degree and reaction in the growth chamber air pressure.

2. The boron-containing nano-catalyst alloy particles used in the present invention are mainly Fe-B, Ni-B, Co-B, Fe-Ni-B, Fe-Co-B, Ni-Co-B, B elemental substances, etc. Its general formula is F _x B _100-x , Ni _y B _100-y Co _z B _100-z Fe _a NibB _100-ab Fe _a CobB _100-ab , x, y, z take 30-80, a+b takes 30-80. The boron simple substance nano-particles used in the present invention are amorphous boron with a particle diameter of 20-80nm.

3. Available compound solid phase reaction (Hu Zheng et al., Chinese patent ZL 96117127.8), mechanical ball milling (P.Ruskanen

et al.J.Non-cryst.Solids 224(1998) 36) or liquid phase reaction (Z.Hu et al, J.Chem.Soc.: Chem.Commun.(1995) 247) and other methods to prepare the above-mentioned boron-containing Nano-catalyst alloy particles.

4. The present invention generates BN and B-C-N nanostructures at 700-900°C, or under nitrogen atmosphere plasma reaction conditions.

5. The present invention provides BN and B-C-N fullerene nanoparticles and BN and B-C-N nanocapsules encapsulating Fe-B, Ni-B, Co-B, B, etc. The fullerene-like nanoparticles provided by the present invention are polyhedral hollow nanostructures, generally multi-layered, with different reaction conditions, the outer diameter is in the range of 20-200 nm, and the tube wall thickness is in the range of 5-30 nm; wrapped Fe- B, BN and B-C-N nanocapsules of Ni-B, Co-B, and B nanoparticles have the same scale as fullerene-like nanoparticles, with a diameter of about 20-200 nanometers, in which BN and B-C-N shells are composed of h-BN, B-C-N formed layered structure. Fullerene-like nanoparticles also include open hollow nanosphere structures.

6. By controlling the process conditions, BN and B-C-N nanocapsules and fullerene-like nanoparticles with different particle sizes and wall thicknesses can be obtained. The main reason is to control the particle size of the catalyst particle and the boron content of the catalyst to control the particle size of nanocapsules and fullerene-like nanoparticles; by adjusting the reaction gas flow rate and the length of reaction time, nanocapsules and fullerene-like nanoparticles with different wall thicknesses can be obtained. Nanoparticles.

7. The method for preparing BN-like fullerene nanoparticles in the present invention is to first place the obtained boron-containing nanoparticles in the above-mentioned growth chamber, bake them at 500-700° C. under an argon atmosphere for about 3 hours, and then heat up to At 700-900°C, N ₂ /NH ₃ (4% NH ₃ ) mixed gas is fed to carry out nitriding reaction to obtain an intermediate product containing BN nanocapsules. Then, the BN nanocapsules are subjected to high temperature treatment at 1350-1450° C. (typically 1400° C.) in an inert atmosphere, or 1-3 M hydrochloric acid or sulfuric acid treatment to obtain BN fullerene nanoparticles.

8. Preparation of the present invention The method for preparing BCN-like fullerene nanoparticles in the present invention is to first place the obtained boron-containing nano-catalyst particles in the above-mentioned growth chamber, and bake them at 500-700° C. for 3 hours under an argon atmosphere. Then the temperature is raised to 700-900° C., and a gaseous C source mixture such as N ₂ /NH ₃ (4% NH ₃ ) and CH ₄ is introduced to react to obtain BCN nanocapsules. Then, the BCN nanocapsules are subjected to high temperature treatment at 1350-1450° C. (typically 1400° C.) in an inert atmosphere, or 1-3 M hydrochloric acid or sulfuric acid and other inorganic acids for further reaction to obtain BCN-like fullerene nanoparticles. The gaseous C source can also be C ₆ H ₆ , C ₂ H ₂ or C ₂ H ₄ . The temperature of the acid treatment is about 40-70°C 2M, and the acid treatment time is 12-24 hours.

9. The N source in the present invention can also be solid, and the solid N source is ammonium chloride (NH ₄ Cl) or urea (CO(NH ₂ ) ₂ ); the C source can also be solid, and the solid C source is activated carbon or graphite powder.

Features of the present invention are as follows:

1. A method for preparing single BN or B-C-N fullerene nanoparticles was developed. And the shape of the product can be controlled by adjusting the particle size of the raw material, reaction temperature, gas flow, reaction time and other conditions.

2. The reaction process of "form the shell first and then remove the nucleus" of the present invention provides a new idea for synthesizing other nano-cage structures.

3. It can be seen from the enlarged photo that the present invention especially develops a method for preparing BN or B-C-N fullerene nanoparticles with high purity and single form.

Description of drawings

Figure 1: Schematic diagram of the thermal chemical vapor deposition reaction device for growing BN and B-C-N zero-dimensional nanostructures according to the present invention:

(1) Stop valve; (2) Mass flow meter; (3) High temperature furnace; (4) Thermocouple; (5) Temperature controller; (6) Corundum crucible; (7) Filter screen; (8) Vacuum gauge; (9) Vacuum pump;

Figure 2: Schematic diagram of the plasma-enhanced chemical vapor deposition reaction device for growing BN and B-C-N zero-dimensional nanostructures according to the present invention:

(1) globe valve; (2) mass flowmeter; (3-1) quartz tube; (4-1) cooling water; (5-1) microwave radiation; (6-1) microwave plasma source; (7) filter Net; (8) vacuum gauge; (9) vacuum pump;

Fig. 3: HRTEM photo of BN nanocapsules prepared at 850°C with Fe ₇₅ B ₂₅ nanoparticle catalyst by the method of the present invention.

Fig. 4: TEM photo of BN nanocapsules prepared at 900°C with Ni ₇₀ B ₃₀ nanoparticle catalyst by the method of the present invention.

Fig. 5: HRTEM photo of BCN nanocapsules prepared at 900°C with Co ₇₅ B ₂₅ nanoparticle catalyst by the method of the present invention.

Fig. 6: TEM photo of BN nanocapsules prepared by the method of the present invention with Fe ₇₀ B ₃₀ nanoparticle catalyst under plasma excitation.

Fig. 7: TEM photo of the mixture of BN fullerene-like nanoparticles and BN nanocapsules prepared at 750°C with the Fe ₅₀ B ₅₀ nanoparticle catalyst by the method of the present invention.

Figure 8: TEM photo of BN nanoparticles prepared at 800°C with Fe ₃₅ Ni ₃₅ B ₃₀ nanoparticle catalysts using the method of the present invention

Figure 9: TEM and HRTEM photographs of BN fullerene nanoparticles prepared by using the method of the present invention to react at 750 ° C with Fe ₇₀ B ₃₀ nanoparticle catalysts, and then acid treatment

Figure 10: HRTEM photo of BN-like fullerene nanoparticles prepared by using the method of the present invention with Co ₃₅ Ni ₃₅ B ₃₀ nanoparticle catalysts reacted at 900 ° C, and then treated with acid

Figure 11: TEM photo of BCN-like fullerene nanoparticles prepared by reacting with Co ₇₅ B ₂₅ nanoparticle catalyst at 900°C by the method of the present invention, and then treated with acid

Fig. 12: TEM photos of BN nanocapsules (Fig. 12a) and BN fullerene-like nanoparticles (Fig. 12b) with a diameter of 20-50nm prepared at 900°C by the method of the present invention with Fe ₅₀ B ₅₀ nanoparticle catalyst.

Fig. 13: TEM photos of BCN fullerene-like nanoparticles with a diameter of 50-200nm prepared by the method of the present invention with nanoparticle catalysts such as Co ₃₅ Ni ₃₅ B ₃₀ reacting at 900°C and undergoing acid treatment. Wherein 40-120nm BN fullerene nanoparticles (Fig. 13a), 60-150nm BN fullerene nanoparticles (Fig. 13b), 60-150nm BN fullerene nanoparticles (Fig. 13c), diameter BN fullerene-like nanoparticles of 60-150 nm (Fig. 13d).

Figure 14: TEM photo of BN-like fullerene-like nanoparticle hollow spheres with a diameter of about 200 nm prepared by reacting at 900°C with Ni ₇₀ B ₃₀ and other nanoparticle catalysts by the method of the present invention and subjected to high-temperature treatment. BN fullerene-like nanoparticles with a diameter of 80-350 nm (see Fig. 14c, 14d). 80-350nm BN fullerene-like nanoparticles (see Figure 14a, 14b).

Figure 15: Boron nanoparticles are prepared by the method of the present invention, and BN nanocapsules and fullerene-like nanoparticles are prepared using this as a boron source. B nanoparticles with a diameter of 40-100 nm ( FIG. 15 a ), BN nanocapsules wrapped with B with a diameter of about 100 nm ( FIG. 15 b ), and BN fullerene-like nanoparticles with a diameter of 100-150 nm ( FIG. 15C ).

Figure 16: XRD spectrum of BN-like fullerene nanoparticles prepared by the method of the present invention.

Figure 17: EDS spectrum of BN-like fullerene nanoparticles prepared by the method of the present invention.

Detailed ways

Example 1: BN nanocapsules were prepared at 850° C. with Fe ₇₅ B ₂₅ nanoparticle catalyst.

Fe ₇₅ B ₂₅ nanoparticles with an average particle size of about 40 nm were prepared by liquid-phase reaction of 1 mol/L KBH ₄ and 0.1 mol/L FeSO ₄ . The obtained Fe-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 850°C at a rate of 10°C per minute under an argon atmosphere. The argon filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced, and the reaction was carried out at 850° C. for 3 hours. A crystalline BN layer is covered on the surface of the Fe-B nanoparticles to obtain Fe-B-wrapped BN nanocapsules with a diameter of 30-100 nm (see FIG. 3 ).

The N source in this embodiment can also be in a solid state, and the solid N source is ammonium chloride (NH ₄ Cl) or urea (CO(NH ₂ ) ₂ ) to obtain the same product.

Example 2: BN nanocapsules were prepared at 900° C. with Ni ₇₀ B ₃₀ nanoparticle catalyst.

Ni ₇₀ B ₃₀ nanoparticles with an average particle size of about 50 nm were prepared by liquid-phase reaction of 1 mol/L KBH ₄ and 0.1 mol/L NiCl ₂ . Use this as a catalyst and place it in the center of the corundum tube, then repeatedly fill it with argon and evacuate it with a mechanical pump for 3-5 times, and raise the temperature to 900°C at a rate of 10°C per minute under an argon atmosphere. The argon gas filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced to react at 900° C. for 2 hours. A crystalline BN layer is covered on the surface of the catalyst particle to obtain a Ni-B-wrapped BN nanocapsule with a diameter of about 40-120nm. (See Figure 4)

Example 3: BN nanocapsules were prepared at 900° C. with Co ₇₅ B ₂₅ nanoparticle catalyst.

Co ₇₅ B ₂₅ nanoparticles with an average particle size of about 30 nanometers were prepared by liquid-phase reaction of 1 mol/L KBH ₄ and 0.1 mol/L CoCl ₂ . The obtained Co-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 900°C at a rate of 10°C per minute under an argon atmosphere. The argon gas filling was stopped, and 100 SCCM of N ₂ /NH ₃ /C ₂ H ₂ (4% NH ₃ , 10% C ₂ H ₂ ) mixed gas was introduced to react at 900° C. for 2 hours. A BCN layer is covered on the surface of the catalyst particles to obtain BCN nanocapsules wrapped with Ni-B with a diameter of about 30-100 nm. (See Figure 5)

Example 4: BN nanocapsules prepared with Fe ₇₀ B ₃₀ nanoparticle catalyst under plasma excitation.

Fe ₇₀ B ₃₀ particles with an average particle size of 40-200nm are prepared from iron powder and boron powder by mechanical ball milling. Use this as a catalyst and place it in the central area of the quartz tube, then repeatedly fill it with argon and evacuate it with a mechanical pump for 3-5 times, then turn on the plasma source under a low-pressure hydrogen/argon atmosphere, start glowing, and feed 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) gas mixture, react for 1 hour. A BN layer is covered on the surface of the catalyst particles to obtain Fe-B-coated BN nanocapsules with a diameter of about 40-200nm. (shown in Figure 6). BN nanocapsules with the same shape were prepared with Co ₇₅ B ₂₅ and Ni ₇₀ B ₃₀ in the same particle size range under plasma excitation.

Example 5: BN-like fullerene nanoparticles and BN nanocapsule mixtures prepared at 750°C with Fe ₅₀ B ₅₀ nanoparticle catalysts

Mix anhydrous FeCl ₃ and KBH ₄ at a molar ratio of 1:3.3, ball mill in a planetary ball mill for 8 hours, and then roast in an argon atmosphere for 3 hours to obtain Fe ₅₀ B ₅₀ nanometers with a particle size of about 30-100 nm particle. The obtained Fe-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 750°C at a rate of 10°C per minute under an argon atmosphere. The argon gas filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced to react at 750° C. for 3 hours. Around the original Fe-B nano catalyst particles, BN fullerene nanoparticles with a diameter of 20-50nm and BN nanocapsules wrapped with Fe-B with a diameter of 30-150nm were obtained (see Figure 7).

Example 6: TEM photo of BN nanoparticles prepared at 800° C. with Fe ₃₅ Ni ₃₅ B ₃₀ nanoparticle catalyst.

Fe ₃₅ Ni ₃₅ B ₃₀ with an average particle size of about 25 nanometers was obtained by reducing the mixed solution of 0.1 mol/L FeCl ₂ and NiCl ₂ (Fe ²⁺ : Ni ²⁺ = 1: 1) with 0.5 mol/L KBH ₄ nanoparticles. The obtained Fe-Ni-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 800°C at a rate of 10°C per minute under an argon atmosphere. The argon gas filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced to react at 800° C. for 2 hours. BN nanoparticles with a diameter of 10-15 nm were obtained in the Fe-Ni-B nanoparticle bed region (see Figure 8).

Example 7: Nitriding with Fe ₅₀ B ₅₀ nanoparticle catalyst at 750° C., followed by acid treatment to prepare BN fullerene nanoparticles.

Mix anhydrous FeCl ₃ and KBH ₄ at a molar ratio of 1:3.3, ball mill in a planetary ball mill for 8 hours, and then roast in an argon atmosphere for 3 hours to obtain Fe ₅₀ B ₅₀ nanoparticles with a particle size of about 30-100 nm . The obtained Fe-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 750°C at a rate of 10°C per minute under an argon atmosphere. The argon gas filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced to react at 750° C. for 3 hours. The resulting product was treated in 2M hydrochloric acid at 60°C for 24 hours. BN fullerene-like nanoparticles with a diameter of 20-50 nm were obtained (see FIG. 9 ).

Example 8: Nitriding with Co ₃₅ Ni ₃₅ B ₃₀ nanoparticle catalyst at 900° C., followed by acid treatment to prepare BN fullerene nanoparticles.

Co ₃₅ Ni ₃₅ B ₃₀ with an average particle size of about 25 nanometers can be obtained by reducing the mixed solution of 0.1 mol/L FeCl ₂ and CoCl ₂ (Fe ²⁺ : Ni ²⁺ = 1: 1) by 0.5 mol/L KBH ₄ nanoparticles. The obtained Fe-Co-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 900°C at a rate of 10°C per minute under an argon atmosphere. The argon filling was stopped, and 100 SCCM of N ₂ /NH ₃ (10% NH ₃ ) mixed gas was introduced, and the reaction was carried out at 900° C. for 2 hours. The resulting product was treated in 2M hydrochloric acid at 50°C for 24 hours. BN fullerene-like nanoparticles with a diameter of 20-40 nm were obtained (see FIG. 10 ).

Example 9: Co ₇₅ B ₂₅ nanoparticle catalyst was used to react at 900° C., and then acid treatment was used to prepare BCN-like fullerene nanoparticles.

Co ₇₅ B ₂₅ nanoparticles with an average particle size of about 30 nm were prepared by reducing 0.1 mol/L CoCl ₂ mixture (Fe ²⁺ :Co ²⁺ =3:1) with 1 mol/L KBH ₄ . Use this as a catalyst and place it in the center of the corundum tube, then repeatedly fill it with argon and evacuate it with a mechanical pump for 3-5 times, and raise the temperature to 900°C at a rate of 10°C per minute under an argon atmosphere. The argon gas filling was stopped, and 100 SCCM of N ₂ /NH ₃ (10% NH ₃ ) mixed gas and 50 SCCM of ethylene were introduced to react at 900° C. for 3 hours. The resulting product was treated in 2M hydrochloric acid at 70°C for 16 hours. BCN fullerene-like nanoparticles with a diameter of 20-60 nm were obtained (see FIG. 11 ).

The gaseous C source that can be used in the present invention can also be CH ₄ , C ₂ H ₂ or C ₂ H ₄ . Solid carbon sources can also be used: activated carbon or graphite powder is placed in the central region of the corundum tube along with the catalyst. Then raise the temperature to 850-900° C., and react with 100 SCCM N ₂ /NH ₃ (10% NH ₃ ) mixed gas for 3 hours. Almost identical products were obtained.

Plasma growth of BCN-like fullerene nanoparticles is also possible: turn on the plasma source under a low-pressure hydrogen/argon atmosphere, use the above conditions, start glowing, and feed 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixture Gas, reacted for 1 hour. A BCN layer is covered on the surface of the catalyst particles to obtain fullerene-like nanoparticles with a diameter of about 40-200 nm.

Example 10: Fe ₇₀ B ₃₀ nanoparticle catalyst was used to react at 850° C., and then treated with acid to prepare BN fullerene nanoparticles with an average diameter of 50 nm.

Fe ₇₀ B ₃₀ nanoparticles with an average particle size of about 40 nm were prepared by the liquid phase reaction of 1 mol/L KBH ₄ and 0.1 mol/L FeSO ₄ . The obtained Fe-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 850°C at a rate of 10°C per minute under an argon atmosphere. The argon filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced, and the reaction was carried out at 850° C. for 3 hours. A crystalline BN layer is covered on the surface of the Fe-B nanoparticles to obtain Fe-B-wrapped BN nanocapsules with a diameter of 30-60 nm (see FIG. 12 a ). The resulting product was treated in 2M hydrochloric acid at 60°C for 24 hours. BN fullerene-like nanoparticles with an average diameter of 50 nm were obtained (see FIG. 12b ).

Example 11: Ni ₇₀ B ₃₀ nanoparticle catalyst was reacted at 900° C., and then treated with acid to prepare BN fullerene nanoparticles with an average diameter of about 80 nm.

Fe ₇₀ B ₃₀ nanoparticles were prepared by liquid-phase reaction of 1mol/L KBH ₄ and 0.1mol/L NiSO ₄ . The obtained Ni-B nanoparticles were placed in the central area of the corundum tube, and then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature was raised to 900° C. at a rate of 10° C. per minute under an argon atmosphere. The argon filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced, and the reaction was carried out at 900° C. for 3 hours. A crystalline BN layer is covered on the surface of the Co-B nanoparticle to obtain BN nanocapsules wrapped with Ni-B with a diameter of 40-120nm. The resulting product was treated in 2M hydrochloric acid at 60°C for 24 hours. BN fullerene-like nanoparticles with a diameter of 40-120 nm were obtained (see FIG. 13 a ).

Example 12: Co ₇₀ B ₃₀ nanoparticle catalyst was used to react at 900° C., and then treated with acid to prepare BN fullerene nanoparticles with an average diameter of about 80 nm.

Co ₇₀ B ₃₀ nanoparticles were prepared by the liquid phase reaction of 1mol/L KBH ₄ and 0.1mol/L CoSO ₄ . The obtained Co-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 900°C at a rate of 10°C per minute under an argon atmosphere. The argon gas filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced to react at 900° C. for 3 hours. A crystalline BN layer is covered on the surface of the Co-B nanoparticle to obtain a BN nanocapsule with a diameter of 60-150nm covering the Co-B. The resulting product was treated in 2M hydrochloric acid at 60°C for 24 hours. BN fullerene-like nanoparticles with a diameter of 60-150 nm were obtained (see FIG. 13b ).

Example 13: Fe ₅₀ B ₅₀ nanoparticle catalyst was used to react at 900° C., and then high-temperature treatment under an inert atmosphere was used to prepare BN-based fullerene nanoparticles with an average diameter of about 100 nm.

Mix anhydrous FeCl ₃ and KBH ₄ at a molar ratio of 1:3.3, ball mill in a planetary ball mill for 8 hours, and then roast in an argon atmosphere for 3 hours to obtain Fe ₅₀ B ₅₀ nanoparticles with a particle size of about 30-100 nm . The obtained Fe-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 900° C. at a rate of 10° C. per minute under an argon atmosphere. The argon gas filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced to react at 900° C. for 3 hours. A crystalline BN layer is covered on the surface of the Fe-B nanoparticle to obtain BN nanocapsules with a diameter of 60-150nm covering Fe-B. The resulting product was treated in an argon atmosphere at 14000°C for 24 hours. BN fullerene-like nanoparticles with a diameter of 60-150 nm were obtained (see FIG. 13c ).

Example 14: Fe ₃₅ Co ₃₅ B ₃₀ nanoparticle catalyst was reacted at 900° C., and then BN-like fullerene nanoparticles with an average diameter of about 100 nm were prepared by high temperature treatment under an inert atmosphere.

Fe ₃₅ Co ₃₅ B ₃₀ with an average particle size of about 80 nanometers can be obtained by reducing the mixed solution of 0.1 mol/L FeCl ₂ and CoCl ₂ (Fe ²⁺ : Co ²⁺ = 1: 1) by 0.5 mol/L KBH ₄ nanoparticles. The obtained Fe-Co-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 900°C at a rate of 10°C per minute under an argon atmosphere. The argon filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced, and the reaction was carried out at 900° C. for 3 hours. The surface of the Fe-Co-B nanoparticles is covered with a BN layer to obtain Fe-B-wrapped BN nanocapsules with a diameter of 40-150nm. The resulting product was treated in 2M hydrochloric acid at 60°C for 24 hours. The obtained product was treated in an argon atmosphere at 14000° C. for 24 hours to obtain BN fullerene-like nanoparticles with a diameter of 60-150 nm (see FIG. 13 d ).

Example 15 Fe ₅₀ B ₅₀ nanoparticle catalyst was used to react at 900° C., and then treated with acid to prepare BN fullerene-like complete hollow spheres with an average diameter of about 200 nm and open hollow spheres.

Mix partially deliquesced anhydrous FeCl ₃ and KBH ₄ at a molar ratio of 1:3.3, ball mill in a planetary ball mill for 8 hours, and then roast in an argon atmosphere for 3 hours to obtain Fe ₅₀ B with a particle size of about 50-300nm ₅₀ nm particles. The obtained Fe-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 900° C. at a rate of 10° C. per minute under an argon atmosphere. The argon filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced, and the reaction was carried out at 900° C. for 3 hours. A crystalline BN layer is covered on the surface of the Fe-B nanoparticle to obtain BN nanocapsules with a diameter of 80-350nm covering Fe-B. The resulting product was treated in 2M hydrochloric acid at 60°C for 24 hours. BN fullerene-like nanoparticles with a diameter of 80-350 nm were obtained (see Fig. 14a, 14b). The XRD spectrum of the BN-like fullerene nanoparticles is shown in FIG. 16 , and the EDS spectrum of the BN-like fullerene nanoparticles is shown in FIG. 17 .

Example 16: Using Fe ₅₀ B ₅₀ nanoparticle catalyst to react at 900°C, and then high-temperature treatment under an inert atmosphere to prepare polyhedral BN fullerene-like complete hollow spheres with an average diameter of about 200 nm and open hollow spheres.

Mix partially deliquesced anhydrous FeCl ₃ and KBH ₄ at a molar ratio of 1:3.3, ball mill in a planetary ball mill for 8 hours, and then roast in an argon atmosphere for 3 hours to obtain Fe ₅₀ B with a particle size of about 50-300nm ₅₀ nm particles. The obtained Fe-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 900° C. at a rate of 10° C. per minute under an argon atmosphere. The argon filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced, and the reaction was carried out at 900° C. for 3 hours. A crystalline BN layer is covered on the surface of the Fe-B nanoparticle to obtain BN nanocapsules with a diameter of 80-350nm covering Fe-B. The obtained product was treated in an argon atmosphere at 1400° C. for 24 hours to obtain BN fullerene-like nanoparticles with a diameter of 80-350 nm (see FIGS. 14c and 14d ).

Example 17: Using borane and hydrogen as raw materials, B nanoparticles were reacted under microwave plasma conditions.

Using borane, hydrogen reacts under the condition of microwave plasma to prepare B nanoparticles with a diameter of 40-100. (See Figure 15a)

Example 18: Nitriding B nanoparticles at about 1100° C. to prepare BN-wrapped B nanocapsules.

Place B nanoparticles in the central area of the corundum tube, then repeatedly fill with argon and evacuate with a mechanical pump for 3-5 times, and raise the temperature to 1100°C at a rate of 10°C per minute under an argon atmosphere. The argon filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced, and the reaction was carried out at 1100° C. for 3 hours. A crystalline BN layer is covered on the surface of the B nanoparticle to obtain BN nanocapsules with a diameter of about 100 nm. (See Figure 15b)

The same method was used to prepare B-C-N-wrapped B nanocapsules. The reaction was simultaneously fed with 50 SCCM of ethylene.

Example 19: The BN nanocapsules encapsulating B were denucleated by pickling to obtain BN fullerene-like nanoparticles with a diameter of about 100-150 nm.

The BN nanocapsules wrapped with B were treated in 2M hydrochloric acid at 60°C for 24 hours. BN fullerene-like nanoparticles with a diameter of 100-150 nm were obtained (see FIG. 15C ). B nanoparticles with a diameter of 40-100. (See Fig. 15a) BN nanocapsules wrapped with B with a diameter of about 100 nm. (See Figure 15b).

Example 20: The general growth conditions of nanocapsules are as follows: first place the prepared boron-containing (30-50%) nanoparticles in a growth chamber, raise the temperature to 1000-1300° C., and feed _70-150 SCCM of N at the same time /NH ₃ (4% NH ₃ ) reaction, and can control the size of boron-containing nano-particles to control the diameter of BN nano-capsules. It is also possible to feed carbon-containing gas at the same time to grow BCN nanocapsules with an outer layer.

Example 21: Fullerene-like nanoparticles are polyhedral hollow nanostructures with a size of 20-300nm, and the general growth conditions are: BN or B-C-N nanocapsules are burned at high temperature (1400°C), and the core is free from the shell out, the hollow shell forms fullerene-like nanoparticles; or the boron-containing core is dissolved in an acid solution, leaving a hollow shell to form fullerene-like nanoparticles.

Example 22: BCN nanocapsules were prepared at 900° C. using the same method as in Example 2 with Ni ₇₀ B ₃₀ nanoparticle catalyst.

Ni ₇₀ B ₃₀ nanoparticles with an average particle size of about 50 nm were prepared by liquid-phase reaction of 1 mol/L KBH ₄ and 0.1 mol/L NiCl ₂ . Use this as a catalyst and place it in the center of the corundum tube, then repeatedly fill it with argon and evacuate it with a mechanical pump for 3-5 times, and raise the temperature to 900°C at a rate of 10°C per minute under an argon atmosphere. The argon filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced, and 50 SCCM of ethylene was added for the reaction. The reaction was carried out at 900° C. for 2 hours. A crystalline BCN layer is covered on the surface of the catalyst particles, and BN nanocapsules wrapped with Ni-B with a diameter of about 40-120 nm are also obtained.

Example 23: BN nanocapsules were prepared at 900° C. using the Co ₇₅ B ₂₅ nanoparticle catalyst under the conditions of Example 3.

Co ₇₅ B ₂₅ nanoparticles with an average particle size of about 30 nanometers were prepared by liquid-phase reaction of 1 mol/L KBH ₄ and 0.1 mol/L CoCl ₂ . The obtained Co-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 900°C at a rate of 10°C per minute under an argon atmosphere. Stop filling argon, feed 100 SCCM of N ₂ /NH ₃ /C ₂ H ₂ (4% NH ₃ , 10% C ₂ H ₂ ) mixed gas, and add 50 SCCM of ethane at the same time, react at 900°C for 2 Hour. A BCN layer is covered on the surface of the catalyst particles to obtain BCN nanocapsules wrapped with Ni-B with a diameter of about 30-100 nm.

Example 24: Following the conditions of Example 4, BCN nanocapsules were prepared with Fe ₇₀ B ₃₀ nanoparticle catalyst under plasma excitation.

Fe ₇₀ B ₃₀ particles with an average particle size of 40-200nm are prepared from iron powder and boron powder by mechanical ball milling. Use this as a catalyst and place it in the central area of the quartz tube, then repeatedly fill it with argon and evacuate it with a mechanical pump for 3-5 times, then turn on the plasma source under a low-pressure hydrogen/argon atmosphere, start glowing, and feed 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) gas mixture, react for 1 hour. A BN layer is covered on the surface of the catalyst particles to obtain Fe-B-coated BCN nanocapsules with a diameter of about 40-200nm. BCN nanocapsules with the same shape were prepared with Co ₇₅ B ₂₅ and Ni ₇₀ B ₃₀ in the same particle size range under plasma excitation.

Example 25: A mixture of BN-like fullerene nanoparticles and BN nanocapsules prepared at 750° C. using the Fe ₅₀ B ₅₀ nanoparticle catalyst under the conditions of Example 5.

Mix anhydrous FeCl ₃ and KBH ₄ at a molar ratio of 1:3.3, ball mill in a planetary ball mill for 8 hours, and then roast in an argon atmosphere for 3 hours to obtain Fe ₅₀ B ₅₀ nanoparticles with a particle size of about 30-100 nm . The obtained Fe-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 750°C at a rate of 10°C per minute under an argon atmosphere. The argon gas filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced, while 50 SCCM of ethylene was introduced, and the reaction was carried out at 750° C. for 3 hours. Around the original Fe-B nano-catalyst particles, BN-like fullerene nanoparticles with a diameter of 20-50 nm and BCN nano-capsules wrapped with Fe-B with a diameter of 30-150 nm are obtained.

Example 26: BCN nanoparticles prepared at 800° C. under the conditions of Example 6 using Fe ₃₅ Ni ₃₅ B ₃₀ nanoparticle catalyst.

Fe ₃₅ Ni ₃₅ B ₃₀ with an average particle size of about 25 nanometers can be obtained by reducing the mixed solution of 0.1 mol/L FeCl ₂ and NiCl ₂ (Fe ²⁺ : Ni ²⁺ = 1: 1) with 0.5 mol/L KBH ₄ nanoparticles. The obtained Fe-Ni-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 800°C at a rate of 10°C per minute under an argon atmosphere. Stop filling the argon gas, feed 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas, and feed 50 SCCM of ethane at the same time (solid activated carbon can also be placed near the central area, and the product is also BCN nanoparticles ), reacted at 800°C for 2 hours. BCN nanoparticles with a diameter of 10-15nm were obtained in the Fe-Ni-B nanoparticle bed region.

Example 27: Following the conditions of Example 7, the Fe ₅₀ B ₅₀ nanoparticle catalyst was used for nitriding at 750° C., followed by acid treatment to prepare BCN-like fullerene nanoparticles.

Mix anhydrous FeCl ₃ and KBH ₄ at a molar ratio of 1:3.3, ball mill in a planetary ball mill for 8 hours, and then roast in an argon atmosphere for 3 hours to obtain Fe ₅₀ B ₅₀ nanoparticles with a particle size of about 30-100 nm . The obtained Fe-B nanoparticles are placed in the central area of the corundum tube, then repeatedly filled with argon and evacuated by a mechanical pump for 3-5 times, and the temperature is raised to 750°C at a rate of 10°C per minute under an argon atmosphere. The argon gas filling was stopped, and 100 SCCM of N ₂ /NH ₃ (4% NH ₃ ) mixed gas was introduced to react at 750° C. for 3 hours. The resulting product was treated in 2M hydrochloric acid at 60°C for 24 hours. BCN-like fullerene nanoparticles with a diameter of 20-50 nm are obtained.

Claims (4)

1. A method for preparing BN or BCN nanocapsules or fullerene-like nanoparticles, characterized in that nitrogen-containing gas or solid is a nitrogen source, and the nano-catalyst alloy particles containing 20 to 70% of boron are used as a boron source. React in a tube furnace at 700-900°C or under microwave plasma excitation for 1-5 hours to controlly grow BN nanocapsules, or a mixture of BN nanocapsules and fullerene-like nanoparticles; at the same time, in carbon-containing gases or Under the condition that the solid is a carbon source, grow BCN nanocapsules or a mixture of BCN nanocapsules and fullerene-like nanoparticles; the boron-containing nanocatalyst alloy particles include Fe-B, Ni-B, Co-B, Fe- Ni-B, Fe-Co-B or _Ni -Co-B, its general formula is _{FexB100 -x} , _{NiyB100 -y} , _{CozB100 -z} , _{FeaNibB100 -ab} or Fe _a Co _b B _100-ab , x, y and z are 30-80, and a+b is 30-80. 2. The method for preparing BN or BCN nanocapsules or fullerene-like nanoparticles according to claim 1, wherein the gaseous N source is N ₂ and NH ₃ , and the gaseous C source refers to CH ₄ , C ₆ H ₆ , C ₂ H ₂ or C ₂ H ₄ , the solid N source is ammonium chloride NH ₄ Cl or urea CO(NH ₂ ) ₂ , and the solid C source is activated carbon or graphite powder. 3. According to the preparation method of BN or B-C-N nanocapsules or fullerene-like nanoparticles according to claim 2 or 3, it is characterized in that the boron-containing nano-catalyst alloy particles refer to a nanometer of FeB, NiB and CoB nanoparticles. Particles, or a mixture of two or three of them. 4. The method for preparing BN or BCN nanocapsules or fullerene-like nanoparticles according to claim 1 or 3, characterized in that anhydrous FeCl _{and KBH} are mixed in a planetary ball mill at a molar ratio of 1:3.3 Ball milling for 8 hours, and then roasting in an argon atmosphere for 3 hours to obtain Fe ₅₀ B ₅₀ nanoparticles with a particle size of 30-100 nm; place the obtained Fe ₅₀ B ₅₀ nanoparticles in the central area of the corundum tube, and then repeatedly fill with argon and Use a mechanical pump to evacuate 3-5 times, and raise the temperature to 750°C at a rate of 10°C per minute under an argon atmosphere; stop filling argon, and feed 100SCCM 4% NH ₃ N ₂ /NH ₃ mixed gas, and at the same time Add 50SCCM of ethylene and react at 750°C for 3 hours; Around the original Fe ₅₀ B ₅₀ Fe-B nano-catalyst particles, BN-like fullerene nanoparticles with a diameter of 20-50nm and wrapped Fe ₅₀ with a diameter of 30-150nm are obtained. BCN nanocapsules of B ₅₀ .

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