Method for preparing coralline-like hollow silicon carbide by sacrifice of metal template

Abstract

The invention relates to a method for preparing coralline-like hollow silicon carbide by sacrifice of a metal template, and belongs to the technical field of metal film materials. Metal or alloy particles are used as a core and a hard template, a silicon dioxide layer and an amorphous carbon layer are sequentially coated through a condensation polymerization reaction, and in the thermal reduction process, reduction characteristics of the metal at high temperature are utilized, and a small amount of hydrogen is used as assistance; a silicon carbide shell can be generated at a relatively low pyrolysis temperature, an external shell layer is prevented from collapsing by utilizing a supporting effect of an internal hard template, and preferably, internal metal and redundant silicon dioxide which does not participate in a reaction are etched off by a mixed acid solution, so that coralline-like hollow silicon carbide is obtained.

Description

Technical Field

[0001] The present invention relates to a method for preparing coral-like hollow silicon carbide by using a sacrificial metal template, and belongs to the technical field of silicon carbide materials. Background Art

[0002] Due to its excellent high-temperature stability, good chemical tolerance, high mechanical strength and unique optoelectronic properties, silicon carbide has broad application prospects in the fields of energy storage, semiconductor devices, functional ceramics and special coatings. In particular, silicon carbide materials with a hollow structure have low density, high specific surface area and hollow structure, which can significantly enhance their application potential in aspects such as exposing active sites as a catalyst carrier, regulating impedance matching for electromagnetic wave absorption, and alleviating volume expansion of the negative electrode of lithium-ion batteries.

[0003] However, traditional silicon carbide preparation methods such as precursor conversion method, chemical vapor deposition method, and carbothermal reduction method generally prepare single crystals, thin films or solid particles and cannot form a hollow structure, and the preparation environment is harsh and the cost is high. The recently proposed template method uses silica microspheres as a silicon source and a hard template, and then undergoes a solid-phase reaction with a carbon shell at an extremely high temperature (about 1400 °C), and then uses hydrofluoric acid to remove the excess silica core to prepare hollow silicon carbide. However, the hollow structure has problems of being easily fragmented and collapsed due to being susceptible to ultra-high temperature, and the prepared hollow silicon carbide is mostly a simple core-shell or single-cavity structure. Summary of the Invention

[0004] Aiming at the problems of single and immature existing hollow silicon carbide preparation processes, easy collapse and fragmentation of the hollow structure, and mostly simple core-shell structures, etc., the present invention proposes a method for preparing coral-like hollow silicon carbide by using a sacrificial metal template, using metal or alloy particles as the core and hard template, sequentially coating a silica layer and an amorphous carbon layer through a polycondensation reaction, and utilizing the reduction characteristics of the metal at high temperature and with the assistance of a small amount of hydrogen during the thermal reduction process, a silicon carbide shell can be formed at a relatively low pyrolysis temperature and the support of the internal hard template can be used to prevent the external shell layer from collapsing. Preferably, the internal metal and the excess silica that did not participate in the reaction are etched away by a mixed acid solution to obtain coral-like hollow silicon carbide.

[0005] A method for preparing coral-like hollow silicon carbide by using a sacrificial metal template, the specific steps are as follows:

[0006] (1) Dissolve a metal salt and urea in deionized water to prepare an aqueous metal ion solution. The aqueous metal ion solution undergoes a hydrothermal reaction at a temperature of 160-180 °C for 10-12 h, followed by solid-liquid separation. The solid is washed successively with deionized water and ethanol, and then vacuum dried to obtain a coral-like metal particle precursor;

[0007] (2) The coral-like metal particle precursor is uniformly dispersed in an isopropanol-deionized water-ammonia water mixed solution to obtain a coral-like metal particle precursor dispersion. Under stirring conditions, tetraethyl orthosilicate is slowly dropped into the coral-like metal particle precursor dispersion and stirred for reaction for 60 - 90 min. After solid-liquid separation, the solid is washed successively with deionized water and ethanol, and dried in vacuum to obtain SiO2@coral-like metal particle precursor;

[0008] (3) The SiO2@coral-like metal particle precursor is uniformly dispersed in deionized water to obtain a SiO2@coral-like metal particle precursor dispersion. Under stirring conditions, Tris hydrochloride buffer solution is slowly dropped into the SiO2@coral-like metal particle precursor dispersion and stirred for reaction for 5 - 8 h. After solid-liquid separation, the solid is washed successively with deionized water and ethanol, and dried in vacuum to obtain amorphous carbon@SiO2@coral-like metal particle precursor;

[0009] (4) The amorphous carbon@SiO2@coral-like metal particle precursor is placed in a tube furnace, and a H2 / Ar2 mixed gas is continuously introduced. Under the atmosphere of the H2 / Ar2 mixed gas, it is heated to 500 - 600 °C at a rate of 5 - 7 °C / min and held for 1.5 - 2 h, and then heated to 800 - 1000 °C at a rate of 2 - 4 °C / min and held for 2 - 3 h, and cooled to room temperature with the furnace to obtain SiC@amorphous carbon@SiO2@coral-like metal particle precursor;

[0010] (5) The SiC@amorphous carbon@SiO2@coral-like metal particle precursor is uniformly dispersed in a hydrofluoric acid-hydrochloric acid mixed acid solution for etching. After solid-liquid separation, the solid is washed successively with deionized water and ethanol, and dried in vacuum to obtain coral-like hollow silicon carbide.

[0011] Preferably, in the step (1), the molar ratio of the metal salt to urea is 1:1.9 - 2.1.

[0012] Preferably, in the step (1), the metal salt is one or more of cobalt chloride, nickel chloride, ferrous chloride, cobalt nitrate, nickel nitrate, and iron nitrate, and the concentration of the metal ion aqueous solution is 0.08 - 0.12 mol / L.

[0013] Preferably, in the step (2), the volume ratio of isopropanol, deionized water, and ammonia water in the isopropanol-deionized water-ammonia water mixed solution is 20:5:0.8 - 1.0, the concentration of the coral-like metal particle precursor dispersion is 4.5 - 6.5 mg / mL, and the volume ratio of the coral-like metal particle precursor dispersion to tetraethyl orthosilicate is 1:0.003 - 0.005.

[0014] Preferably, in step (3), the concentration of the SiO2@coral-like metal particle precursor dispersion is 8-12 mg / mL, and the volume ratio of the SiO2@coral-like metal particle precursor dispersion to the Tris hydrochloride buffer solution is 1:0.04-0.08.

[0015] Preferably, in step (4), the volume fraction of H2 in the H2 / Ar2 mixed gas is 5-10%, and the feeding rate of the H2 / Ar2 mixed gas is 200-300 mL / min.

[0016] Preferably, in step (5), the concentration of hydrofluoric acid in the hydrofluoric acid-hydrochloric acid mixed acid solution is 0.5-1 mol / L, and the concentration of hydrochloric acid is 0.8-1.2 times that of hydrofluoric acid.

[0017] Preferably, in step (5), the etching temperature is 20-40 °C and the time is 5-10 h.

[0018] The beneficial effects of the present invention are as follows:

[0019] (1) In the present invention, metal or alloy particles are used as the core and hard template, and a silica layer and an amorphous carbon layer are sequentially coated through a polycondensation reaction. During the thermal reduction process, the metal or alloy hard template has strong reduction ability at high temperature, and with the assistance of a small amount of hydrogen, the sintering temperature of thermally reduced silicon carbide can be significantly reduced;

[0020] (2) During the thermal reduction process in the present invention, the core metal or alloy also plays a self-supporting role inside, preventing problems such as collapse and fragmentation of the external silicon carbide shell due to thermal stress during the sintering process;

[0021] (3) In the present invention, the metal template is sacrificed, and the morphology of the finally obtained hollow silicon carbide is controlled by the morphology of the initial metal template. Therefore, it can be extended to explore different metal hard template morphologies and sizes to obtain different types of hollow silicon carbide. Description of the Drawings

[0022] Figure 1 SEM image of coral-like hollow silicon carbide prepared by sacrificing the CoFe alloy template in Example 1;

[0023] Figure 2 SEM image of coral-like hollow silicon carbide prepared by sacrificing the CoNi alloy template in Example 2;

[0024] Figure 3 SEM image of coral-like hollow silicon carbide prepared by sacrificing the Co metal template in Example 3;

[0025] Figure 4 XRD patterns of coral-like hollow silicon carbide in Examples 1-3. Detailed Embodiments

[0026] The present invention will be further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the content described.

[0027] Example 1: A method for preparing coral-like hollow silicon carbide using a sacrificial metal template, the specific steps are as follows:

[0028] (1) Dissolve metal salts (cobalt chloride and ferrous chloride) and urea in deionized water to prepare an aqueous metal ion solution. The aqueous metal ion solution is hydrothermally reacted at 180 °C for 10 h, followed by solid-liquid separation. The solid is washed 3 times with deionized water and then 3 times with ethanol, and vacuum dried at 40 °C to obtain a coral-like metal particle precursor (CoFe alloy); the molar ratio of cobalt chloride to ferrous chloride is 1:1, and the total molar amount of cobalt chloride and ferrous chloride to urea is 1:2; the total concentration of cobalt ions and ferrous ions in the aqueous metal ion solution is 0.08 mol / L;

[0029] (2) Uniformly disperse the coral-like metal particle precursor in an isopropanol-deionized water-ammonia water mixed solution to obtain a coral-like metal particle precursor dispersion. Under stirring conditions, slowly drop tetraethyl orthosilicate into the coral-like metal particle precursor dispersion and stir for reaction for 90 min, followed by solid-liquid separation. The solid is washed 2 times with deionized water and then 2 times with ethanol, and vacuum dried at 40 °C to obtain SiO2@coral-like metal particle precursor; the volume ratio of isopropanol, deionized water, and ammonia water in the isopropanol-deionized water-ammonia water mixed solution is 20:5:0.8, the concentration of the coral-like metal particle precursor dispersion is 4.5 mg / mL, and the volume ratio of the coral-like metal particle precursor dispersion to tetraethyl orthosilicate is 1:0.0035;

[0030] (3) Uniformly disperse the SiO2@coral-like metal particle precursor in deionized water to obtain a SiO2@coral-like metal particle precursor dispersion. Under stirring conditions, slowly drop Tris hydrochloride buffer solution into the SiO2@coral-like metal particle precursor dispersion and stir for reaction for 7 h, followed by solid-liquid separation. The solid is washed 3 times with deionized water and then 3 times with ethanol, and vacuum dried at 40 °C to obtain amorphous carbon@SiO2@coral-like metal particle precursor; the concentration of the SiO2@coral-like metal particle precursor dispersion is 10 mg / mL, and the volume ratio of the SiO2@coral-like metal particle precursor dispersion to Tris hydrochloride buffer solution is 1:0.04;

[0031] (4) The amorphous carbon@SiO2@coral-like metal particle precursor is placed in a tube furnace, and a H2 / Ar2 mixed gas (with a H2 volume fraction of 5%) is continuously introduced at a flow rate of 300 mL / min. Under the atmosphere of the H2 / Ar2 mixed gas, it is heated to 600 °C at a rate of 5 °C / min and held for 1.7 h, then heated to 1000 °C at a rate of 3 °C / min and held for 2.2 h, and cooled to room temperature with the furnace to obtain the SiC@amorphous carbon@SiO2@coral-like metal particle precursor;

[0032] (5) The SiC@amorphous carbon@SiO2@coral-like metal particle precursor is uniformly dispersed in a hydrofluoric acid-hydrochloric acid mixed acid solution and etched at 30 °C for 6 h. After solid-liquid separation, the solid is washed 3 times with deionized water and then 3 times with ethanol, and vacuum dried at 40 °C to obtain coral-like hollow silicon carbide; the concentration of hydrofluoric acid in the hydrofluoric acid-hydrochloric acid mixed acid solution is 0.6 mol / L, and the concentration of hydrochloric acid is 0.8 times that of hydrofluoric acid;

[0033] The SEM image of the coral-like hollow silicon carbide prepared by sacrificing the CoFe alloy template in this example is as Figure 1 shown. The hollow silicon carbide exhibits a coral-like morphology, without structural collapse. The particle size is approximately 8 μm, and it is composed of a large number of single-chamber dendrites about 300 nm, and the interiors of the dendrites are interconnected to form a continuous network; the trace white particles inside the dendrites are the CoFe alloy that has not been completely etched, but it also indicates the successful formation of the hollow structure and the silicon carbide shell from the side; the XRD pattern is as Figure 4 shown, showing its typical characteristic peaks of SiC, further indicating the successful preparation of the hollow silicon carbide; the specific surface area of the coral-like hollow silicon carbide in this example obtained by a full-automatic specific surface area analyzer is 31.53 m 2 / g, and the specific surface area is significantly higher than that of conventional micron-sized solid silicon carbide particles.

[0034] Example 2: A method for preparing coral-like hollow silicon carbide by sacrificing a metal template, the specific steps are as follows:

[0035] (1) Metal salts (cobalt chloride and nickel chloride) and urea are dissolved in deionized water to prepare an aqueous metal ion solution. The aqueous metal ion solution undergoes a hydrothermal reaction at 170 °C for 12 h. After solid-liquid separation, the solid is washed 4 times with deionized water and then 2 times with ethanol, and vacuum dried at 45 °C to obtain a coral-like metal particle precursor (CoNi alloy); the molar ratio of cobalt chloride to nickel chloride is 3:1, and the total molar amount of cobalt chloride and nickel chloride to urea is 1:1.9; the total concentration of cobalt ions and ferrous ions in the aqueous metal ion solution is 0.1 mol / L;

[0036] (2) The coral-like metal particle precursors were uniformly dispersed in the isopropanol-deionized water-ammonia water mixed solution to obtain a coral-like metal particle precursor dispersion. Under stirring conditions, tetraethyl orthosilicate was slowly dropped into the coral-like metal particle precursor dispersion and stirred for reaction for 60 min. Solid-liquid separation was carried out. The solid was washed 3 times with deionized water and then 2 times with ethanol, and vacuum dried at a temperature of 45 °C to obtain SiO2@coral-like metal particle precursors; in the isopropanol-deionized water-ammonia water mixed solution, the volume ratio of isopropanol, deionized water, and ammonia water was 20:5:1.0, the concentration of the coral-like metal particle precursor dispersion was 5.0 mg / mL, and the volume ratio of the coral-like metal particle precursor dispersion to tetraethyl orthosilicate was 1:0.005;

[0037] (3) The SiO2@coral-like metal particle precursors were uniformly dispersed in deionized water to obtain a SiO2@coral-like metal particle precursor dispersion. Under stirring conditions, Tris hydrochloride buffer solution was slowly dropped into the SiO2@coral-like metal particle precursor dispersion and stirred for reaction for 6 h. Solid-liquid separation was carried out. The solid was washed 4 times with deionized water and then 3 times with ethanol, and vacuum dried at a temperature of 45 °C to obtain amorphous carbon@SiO2@coral-like metal particle precursors; the concentration of the SiO2@coral-like metal particle precursor dispersion was 8 mg / mL, and the volume ratio of the SiO2@coral-like metal particle precursor dispersion to Tris hydrochloride buffer solution was 1:0.05;

[0038] (4) The amorphous carbon@SiO2@coral-like metal particle precursors were placed in a tube furnace, and a H2 / Ar2 mixed gas (H2 volume fraction was 8%) was continuously introduced at a flow rate of 200 mL / min. Under the atmosphere of the H2 / Ar2 mixed gas, the temperature was raised to 500 °C at a rate of 6 °C / min and held for 2 h, and then the temperature was raised to 800 °C at a rate of 2 °C / min and held for 3 h, and cooled to room temperature with the furnace to obtain SiC@amorphous carbon@SiO2@coral-like metal particle precursors;

[0039] (5) The SiC@amorphous carbon@SiO2@coral-like metal particle precursors were uniformly dispersed in a hydrofluoric acid-hydrochloric acid mixed acid solution and etched at a temperature of 40 °C for 4 h. Solid-liquid separation was carried out. The solid was washed 4 times with deionized water and then 4 times with ethanol, and vacuum dried at a temperature of 45 °C to obtain coral-like hollow silicon carbide; in the hydrofluoric acid-hydrochloric acid mixed acid solution, the concentration of hydrofluoric acid was 0.8 mol / L, and the concentration of hydrochloric acid was 1 time that of hydrofluoric acid;

[0040] The SEM image of the coral-like hollow silicon carbide prepared by sacrificing the CoNi alloy template in this example is as Figure 2As shown, the hollow silicon carbide presents a coral-like morphology without structural collapse. The particle size is about 6 μm, which is composed of a large number of single-cavity dendrites about 350 nm in size, and the interiors of the dendrites are interconnected to form a continuous network. The trace white particles inside the dendrites are the CoNi alloy that has not been completely etched, but this also indicates the successful formation of the hollow structure and the silicon carbide shell from the side. The XRD pattern is as Figure 4 shown, showing its typical characteristic peaks of SiC, further indicating the successful preparation of hollow silicon carbide. The specific surface area of the coral-like hollow silicon carbide in this example was obtained by a full-automatic specific surface area analyzer as 37.25 m 2 / g, and the specific surface area is significantly higher than that of conventional micron-sized solid silicon carbide particles.

[0041] Example 3: A method for preparing coral-like hollow silicon carbide using a sacrificial metal template, the specific steps are as follows:

[0042] (1) Dissolve a metal salt (cobalt chloride) and urea in deionized water to prepare an aqueous metal ion solution. The aqueous metal ion solution is hydrothermally reacted at 175 °C for 11 h, followed by solid-liquid separation. The solid is washed twice with deionized water and then twice with ethanol, and vacuum dried at 50 °C to obtain a coral-like metal Co particle precursor. The molar ratio of cobalt chloride to urea is 1:2.1; the total concentration of cobalt ions and ferrous ions in the aqueous metal ion solution is 0.1125 mol / L;

[0043] (2) Uniformly disperse the coral-like metal Co particle precursor in an isopropanol-deionized water-ammonia mixed solution to obtain a coral-like metal particle precursor dispersion. Under stirring conditions, tetraethyl orthosilicate is slowly dropped into the coral-like metal particle precursor dispersion and stirred for 80 min, followed by solid-liquid separation. The solid is washed three times with deionized water and then three times with ethanol, and vacuum dried at 50 °C to obtain SiO2@coral-like metal particle precursor. The volume ratio of isopropanol, deionized water, and ammonia in the isopropanol-deionized water-ammonia mixed solution is 20:5:0.9, the concentration of the coral-like metal particle precursor dispersion is 6.5 mg / mL, and the volume ratio of the coral-like metal particle precursor dispersion to tetraethyl orthosilicate is 1:0.004;

[0044] (3) The SiO2@coral-like metal particle precursor was uniformly dispersed in deionized water to obtain a dispersion of SiO2@coral-like metal particle precursor. Under stirring conditions, Tris hydrochloride buffer solution was slowly dropped into the dispersion of SiO2@coral-like metal particle precursor and stirred for reaction for 8 h. Solid-liquid separation was carried out. The solid was washed twice with deionized water and then twice with ethanol, and vacuum dried at a temperature of 50 °C to obtain amorphous carbon@SiO2@coral-like metal particle precursor; the concentration of the dispersion of SiO2@coral-like metal particle precursor was 12 mg / mL, and the volume ratio of the dispersion of SiO2@coral-like metal particle precursor to Tris hydrochloride buffer solution was 1:0.06;

[0045] (4) The amorphous carbon@SiO2@coral-like metal particle precursor was placed in a tubular furnace, and a H2 / Ar2 mixed gas (H2 volume fraction was 10%) was continuously introduced at a flow rate of 250 mL / min. Under the atmosphere of the H2 / Ar2 mixed gas, it was heated to 550 °C at a rate of 7 °C / min and held for 1.8 h, and then heated to 950 °C at a rate of 4 °C / min and held for 2.8 h, and cooled to room temperature with the furnace to obtain SiC@amorphous carbon@SiO2@coral-like metal particle precursor;

[0046] (5) The SiC@amorphous carbon@SiO2@coral-like metal particle precursor was uniformly dispersed in a hydrofluoric acid-hydrochloric acid mixed acid solution and etched at a temperature of 20 °C for 6 h. Solid-liquid separation was carried out. The solid was washed three times with deionized water and then twice with ethanol, and vacuum dried at a temperature of 50 °C to obtain coral-like hollow silicon carbide; the concentration of hydrofluoric acid in the hydrofluoric acid-hydrochloric acid mixed acid solution was 1 mol / L, and the concentration of hydrochloric acid was 1.2 times that of hydrofluoric acid concentration;

[0047] The SEM image of the coral-like hollow silicon carbide prepared by sacrificing the metal Co template in this example is as Figure 3 shown. The hollow silicon carbide presents a coral-like morphology, without structural collapse. The particle size is about 8 μm, and it is composed of a large number of single-chamber dendrites about 300 nm, and the interiors of the dendrites are interconnected to form a continuous network; the trace white particles inside the dendrites are the metal Co that has not been completely etched, but it also indicates the successful formation of the hollow structure and the silicon carbide shell from the side; the XRD pattern is as Figure 4 shown, showing that it has typical characteristic peaks of SiC, further indicating the successful preparation of the hollow silicon carbide; the specific surface area of the coral-like hollow silicon carbide in this example was obtained by a fully automatic specific surface area analyzer as 32.91 m 2 / g, and the specific surface area is significantly higher than that of conventional micron-sized solid silicon carbide particles.

[0048] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. A method for preparing coral-like hollow silicon carbide using a sacrificial metal template, characterized in that: The specific steps are as follows: (1) dissolving a metal salt and urea in deionized water to prepare a metal ion aqueous solution, subjecting the metal ion aqueous solution to a hydrothermal reaction at a temperature of 160 to 180° C. for 10 to 12 hours, separating the solid from the liquid, washing the solid with deionized water and ethanol in turn, and vacuum drying to obtain a coral-like metal particle precursor; (2) uniformly dispersing the coral-like metal particle precursor in a mixed solution of isopropanol-deionized water-ammonia water to obtain a coral-like metal particle precursor dispersion, slowly dropping ethyl orthosilicate into the coral-like metal particle precursor dispersion under stirring conditions and stirring the reaction for 60 to 90 minutes, separating the solid from the liquid, washing the solid with deionized water and ethanol in turn, and vacuum drying to obtain SiO2@coral-like metal particle precursor; (3) uniformly dispersing SiO2@coral-like metal particle precursor in deionized water to obtain SiO2@coral-like metal particle precursor dispersion, slowly dripping Tris hydrochloric acid buffer into the SiO2@coral-like metal particle precursor dispersion under stirring conditions and stirring for 5 to 8 hours, separating the solid from the liquid, washing the solid with deionized water and ethanol in turn, and vacuum drying to obtain amorphous carbon@SiO2@coral-like metal particle precursor; (4) placing the amorphous carbon @ SiO2 @ coral-like metal particle precursor in a tube furnace, continuously introducing H2 / Ar2 mixed gas, heating to 500-600°C at a rate of 5-7°C / min and keeping the temperature for 1.5-2h, then heating to 800-1000°C at a rate of 2-4°C / min and keeping the temperature for 2-3h, and cooling to room temperature with the furnace to obtain SiC@amorphous carbon@SiO2@ coral-like metal particle precursor; (5) The SiC@amorphous carbon@SiO2@coral-like metal particle precursor is uniformly dispersed in a hydrofluoric acid-hydrochloric acid mixed acid solution for etching, and the solid-liquid separation is performed. The solid is washed with deionized water and ethanol in turn, and vacuum dried to obtain coral-like hollow silicon carbide.

2. The method for preparing coral-like hollow silicon carbide using a sacrificial metal template according to claim 1, characterized in that: The molar ratio of the metal salt to urea in step (1) is 1:1.9-2.

1.

3. The method for preparing coral-like hollow silicon carbide using a sacrificial metal template according to claim 2, characterized in that: The metal salt in step (1) is one or more of cobalt chloride, nickel chloride, ferrous chloride, cobalt nitrate, nickel nitrate and ferric nitrate, and the concentration of the metal ion aqueous solution is 0.08-0.12 mol / L.

4. The method for preparing coral-like hollow silicon carbide using a sacrificial metal template according to claim 1, characterized in that: In step (2), the volume ratio of isopropanol, deionized water and ammonia water in the isopropanol-deionized water-ammonia water mixed solution is 20:5:0.8-1.0, the concentration of the coral-like metal particle precursor dispersion is 4.5-6.5 mg / mL, and the volume ratio of the coral-like metal particle precursor dispersion to tetraethyl orthosilicate is 1:0.003-0.

005.

5. The method for preparing coral-like hollow silicon carbide using a sacrificial metal template according to claim 1, characterized in that: In step (3), the concentration of the SiO2@ coral-like metal particle precursor dispersion is 8-12 mg / mL, and the volume ratio of the SiO2@ coral-like metal particle precursor dispersion to the Tris hydrochloric acid buffer is 1:0.04-0.

08.

6. The method for preparing coral-like hollow silicon carbide using a sacrificial metal template according to claim 1, characterized in that: In step (4), the volume fraction of H2 in the H2 / Ar2 mixed gas is 5-10%, and the introduction rate of the H2 / Ar2 mixed gas is 200-300 mL / min.

7. The method for preparing coral-like hollow silicon carbide using a sacrificial metal template according to claim 1, characterized in that: In step (5), the concentration of hydrofluoric acid in the hydrofluoric acid-hydrochloric acid mixed acid solution is 0.5 to 1 mol / L, and the concentration of hydrochloric acid is 0.8 to 1.2 times the concentration of hydrofluoric acid.

8. The method for preparing coral-like hollow silicon carbide using a sacrificial metal template according to claim 1, characterized in that: The etching temperature in step (5) is 20 to 40° C. and the etching time is 5 to 10 hours.

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