A method for preparing super-long SiC nanowires on the surface of carbonaceous substrate by using inorganic powder

Abstract

The application discloses a method for preparing super-long SiC nanowires on the surface of carbon-based substrates by using inorganic powder. The method is characterized in that the carbon-based substrate is soaked in a metal salt catalyst solution and then placed on silicon monoxide powder, and heat treatment is carried out under the protection of argon. The method avoids the complicated powder mixing and pretreatment procedures in the traditional process, significantly simplifies the process, reduces the equipment requirements, improves the preparation efficiency and cost-effectiveness. Through the metal salt catalyst induced gas-liquid-solid growth mechanism, in-situ growth of nanowires on the surface of the substrate is realized, and the product is ensured to be high-crystallinity cubic crystal 3C-SiC. The silicon monoxide powder directly provides the reaction source, and the super-long nanowires with smooth surface, uniform diameter and super-high length-diameter ratio are prepared. The bottleneck of low carrier mobility in the traditional process is fundamentally overcome, and the controllable preparation of high-efficiency, low-cost and high-quality super-long 3C-SiC nanowires is realized.

Description

Technical Field

[0001] This invention belongs to the field of SiC nanowire preparation technology, and relates to a method for preparing ultra-long SiC nanowires on a carbonaceous substrate using inorganic powder. Background Technology

[0002] One-dimensional silicon carbide (SiC) nanowires, due to their unique nanostructure, not only inherit the excellent thermal stability, oxidation resistance, corrosion resistance, and high hardness of bulk materials, but also exhibit high aspect ratio, large specific surface area, and unique electrical and optical properties, making them promising for applications in many cutting-edge fields such as high-temperature structural materials, micro / nanoelectronic devices, catalysis, and electromagnetic wave absorption. Compared to shorter one-dimensional SiC nanowires, ultralong SiC nanowires are crucial for exploring the fundamental physical properties of one-dimensional nanostructures on a macroscopic scale and can be more conveniently applied in electronic devices. For example, the literature "Kuang J, Jiang P, Hou X, et al. Dielectric permittivity and microwave absorption properties of SiC nanowires with different lengths[J]. Solid State Sciences, 2019, 91: 73-76." studied the effect of SiC nanowire length on its dielectric constant and microwave absorption characteristics. The results showed that longer nanowires are easier to interconnect, thereby promoting the construction of a continuous conductive network in the matrix. Therefore, longer SiC nanowires exhibit higher electrical conductivity and dielectric constant, resulting in stronger microwave absorption capabilities. Furthermore, in the selection of raw materials for the preparation of ultralong SiC nanowires, inorganic powders (such as silicon powder, silica powder, silicon dioxide powder, and carbon black) are a more attractive choice compared to organic precursors due to their wide availability, low cost, chemical stability, and high safety. However, current processes for preparing ultralong SiC nanowires using inorganic powders typically require powder mixing or pretreatment, making the process relatively complex, inefficient, and demanding on sophisticated equipment.

[0003] Furthermore, regarding SiC crystal structure, compared to the widely used 4H-SiC, cubic 3C-SiC exhibits a carrier mobility approximately 2 to 4 times higher, a high electron affinity of 3.7 eV, and excellent thermal management performance. Therefore, 3C-SiC has proven to have significant research value in fields such as photoelectrocatalytic water splitting, quantum computing, sensors, electromagnetic and biomedical thin films.

[0004] In summary, developing a simple, low-cost, and efficient method for preparing ultralong 3C-SiC nanowires is of great research significance and urgent practical need for overcoming the bottlenecks in existing technologies, such as complex pretreatment, low efficiency, high equipment requirements, and low carrier mobility due to the uncontrollable crystal structure of existing SiC nanowire materials. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for preparing ultra-long SiC nanowires on a carbonaceous substrate using inorganic powder, thereby solving the problems of complex processes, low efficiency, high equipment requirements, and difficulty in controlling the crystal form of the product, which leads to low carrier mobility in the preparation of ultra-long SiC nanowires using inorganic powder in the prior art.

[0006] This invention is achieved through the following technical solution: A method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder includes the following steps: S1: After cleaning and drying the carbonaceous substrate, it is immersed in a metal salt catalyst solution to obtain a carbonaceous substrate loaded with a metal salt catalyst. S2: Spread silica powder evenly on the bottom of a graphite crucible, place the carbonaceous substrate loaded with metal salt catalyst on the silica powder, and then perform heat treatment under an argon atmosphere to obtain ultralong SiC nanowires on the surface of the carbonaceous substrate.

[0007] Optionally, in step S1, the carbon substrate is cleaned and dried, specifically by cleaning the carbon substrate with deionized water, anhydrous ethanol and acetone, and then drying it in an oven at 70~100℃ for 5~24 h.

[0008] Optionally, in step S1, the concentration of the metal salt catalyst solution is 0.05~0.5 mol / L; the soaking time is 1~4 h.

[0009] Optionally, in step S1, after soaking in the metal salt catalyst solution, the substrate is dried at 70~100 °C for 5~24 h to obtain a carbonaceous substrate supported on the metal salt catalyst.

[0010] Optionally, the carbon substrate is one of carbon fiber cloth, graphite sheet, graphite paper, carbon paper, and carbon felt.

[0011] Optionally, the metal salt catalyst solution is one of ferric nitrate, cobalt nitrate, nickel nitrate, ferrous sulfate, cobalt sulfate, nickel sulfate, ferric chloride, cobalt chloride, and nickel chloride.

[0012] Optionally, in step S2, the carbonaceous substrate loaded with the metal salt catalyst is spread evenly on 1~10 g of silica powder.

[0013] Optionally, in step S2, the heating rate during the heat treatment process is 5~10 ℃ / min.

[0014] Optionally, in step S2, the temperature during the heat treatment process is 1300~1600℃ and the time is 1~10 h.

[0015] An ultralong SiC nanowire was prepared by the method described above.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses a method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder. This method involves directly immersing the carbonaceous substrate in a metal salt catalyst solution and placing it on top of silica powder, followed by heat treatment under argon protection. This successfully avoids the complex steps of cumbersome powder mixing or pretreatment of inorganic powders in existing technologies, significantly simplifying the process and reducing equipment requirements, thereby greatly improving preparation efficiency and cost-effectiveness. Simultaneously, by utilizing a metal salt catalyst-induced gas-liquid-solid (VLS) growth mechanism, not only is in-situ directional growth of nanowires on the substrate surface achieved, ensuring the product is cubic 3C-SiC, effectively solving the problem of uncontrollable crystal form, but also, by directly providing the reaction source with silica powder, ultralong nanowires with smooth surfaces, uniform diameters, and ultra-high aspect ratios are prepared. This fundamentally overcomes the bottleneck of low carrier mobility in traditional processes, achieving efficient, low-cost, and high-quality controllable preparation of ultralong 3C-SiC nanowires.

[0017] Furthermore, in step S1, the carbon substrate is cleaned and dried. Specifically, the carbon substrate is cleaned with deionized water, anhydrous ethanol, and acetone, and then placed in an oven to dry at 70-100℃ for 5-24 hours. The multi-solvent gradient cleaning with deionized water, anhydrous ethanol, and acetone can effectively remove water-soluble impurities, organic pollutants, and grease residues from the surface of the carbon substrate, ensuring the cleanliness of the substrate surface. Combined with the drying treatment at 70-100℃ for 5-24 hours, the complete evaporation of moisture inside and on the surface of the substrate is ensured, laying a good interfacial foundation for the uniform loading of the catalyst and the uniform growth of SiC nanowires.

[0018] Furthermore, in step S1, the concentration of the metal salt catalyst solution is 0.05~0.5 mol / L; the soaking time is 1~4 h, which can ensure that the catalyst is fully adsorbed on the carbon substrate surface while avoiding catalyst agglomeration or excessive loading due to excessive concentration or soaking time. The appropriate catalyst loading can form liquid alloy droplets with uniform size and reasonable distribution, providing stable catalytic active sites for the VLS growth mechanism, thereby ensuring that the prepared SiC nanowires have uniform diameter and regular morphology, and avoiding problems such as nanowire coarsening, bifurcation or growth inhibition caused by excessive catalyst.

[0019] Furthermore, in step S1, after soaking in the metal salt catalyst solution, drying at 70~100 ℃ for 5~24 h allows the solvent in the catalyst solution to completely evaporate, promoting the metal salt to uniformly adhere to the carbonaceous substrate surface in solid form. This drying condition matches the substrate cleaning and drying conditions, ensuring the uniformity and stability of the catalyst loading, ensuring that the catalyst can form liquid alloy droplets as expected during the heat treatment process, and ensuring the smooth progress of the VLS growth mechanism.

[0020] Furthermore, the carbon substrate is one of carbon fiber cloth, graphite sheet, graphite paper, carbon paper, and carbon felt. The selection of carbon fiber cloth, graphite sheet, graphite paper, carbon paper, or carbon felt as the carbon substrate stems from the fact that these materials possess excellent high-temperature resistance, chemical stability, and electrical conductivity. They can maintain structural integrity during high-temperature heat treatment at 1300~1600℃ without oxidation or decomposition. Simultaneously, their abundant surface active sites and ability to provide a carbon source allow them to react with silica powder under the action of a catalyst, providing sufficient carbon source and adhesion interface for the growth of SiC nanowires. Different substrates can meet the needs of various application scenarios such as flexible electronic devices and high-temperature structural materials, thus broadening the application range of ultra-long SiC nanowires.

[0021] Furthermore, the metal salt catalyst solution is one of ferric nitrate, cobalt nitrate, nickel nitrate, ferrous sulfate, cobalt sulfate, nickel sulfate, ferric chloride, cobalt chloride, and nickel chloride. These metal salts are easily decomposed into their corresponding elemental metals or alloys at high temperatures, forming low-melting-point liquid alloy droplets with silicon and carbon, effectively catalyzing the VLS growth of SiC nanowires. The catalytic activity and droplet melting point of different metal salts vary slightly, allowing for flexible selection based on the diameter of the target nanowires. Moreover, all are common inorganic salts, widely available and inexpensive, further reducing preparation costs and improving the practicality and scalability of the process.

[0022] Furthermore, in step S2, the carbonaceous substrate loaded with the metal salt catalyst is placed on 1~10 g of silicon monoxide powder. This powder dosage range can ensure a continuous and stable supply of sufficient silicon and oxygen sources during the heat treatment process, meeting the material requirements for the growth of ultra-long SiC nanowires, while ensuring that the product is cubic 3C-SiC. Moreover, this dosage range is compatible with conventional heat treatment equipment, facilitating process scale-up and large-scale production.

[0023] Furthermore, during the heat treatment process, the heating rate is 5~10 ℃ / min, which enables the carbon substrate, catalyst and silicon monoxide powder to be heated uniformly during the heating process. The appropriate heating rate helps the catalyst to be smoothly converted into liquid alloy droplets, providing stable thermodynamic conditions for the nucleation and growth of SiC nanowires, while ensuring the uniform diffusion of gas phase components in the reaction system, thereby improving the crystallinity and morphological uniformity of the nanowires.

[0024] Furthermore, during the heat treatment process, the temperature is 1300~1600℃ and the time is 1~10 h. This temperature range precisely meets the thermodynamic requirements for the decomposition of silicon monoxide powder, the formation of liquid alloy droplets by the metal catalyst, and the nucleation and growth of SiC crystal nuclei. It avoids incomplete reaction and disordered crystal form due to excessively low temperature, or substrate damage and internal defects of nanowires due to excessively high temperature. The appropriate heat treatment time ensures that the nanowires grow to an ultra-long size, while avoiding the increase in energy consumption due to excessive time, thus realizing the preparation of highly efficient and high-quality ultra-long 3C-SiC nanowires. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 The XRD pattern of the ultralong SiC nanowires on the surface of the carbon fiber cloth prepared in Example 5 of this invention; Figure 2 This is a low-magnification SEM image of the ultra-long SiC nanowires on the surface of the carbon fiber cloth prepared in Example 5 of the present invention. Figure 3 This is a high-magnification SEM image of the ultra-long SiC nanowires on the surface of the carbon fiber cloth prepared in Example 5 of the present invention. Detailed Implementation

[0027] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0028] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0029] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0030] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0031] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0032] This invention provides a method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder. This invention combines silicon monoxide (SiO) evaporation with a gas-liquid-solid growth mechanism to achieve the preparation of ultralong 3C-SiC nanowires on a carbonaceous substrate. The SiC nanowires have smooth surfaces, uniform morphology, and millimeter-scale lengths. The technical solution provided by this invention features low raw material costs, simple and controllable processes and equipment, strong versatility, and good reproducibility.

[0033] A method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powders is described below: S1: After cleaning and drying the carbonaceous substrate, it is immersed in a metal salt catalyst solution to obtain a carbonaceous substrate loaded with a metal salt catalyst. The above process is as follows: the carbon substrate is cleaned with deionized water, anhydrous ethanol and acetone respectively, and then dried in an oven at 70~100℃ for 5~24 h; the dried carbon substrate is immersed in a metal salt catalyst solution for 1~4 h, then taken out and placed in an oven to dry at 70~100℃ for 5~24 h to obtain a carbon substrate loaded with a metal salt catalyst. The carbon substrate is one of carbon fiber cloth, graphite sheet, graphite paper, carbon paper, and carbon felt.

[0034] The metal salt catalyst solution is one of ferric nitrate, cobalt nitrate, nickel nitrate, ferrous sulfate, cobalt sulfate, nickel sulfate, ferric chloride, cobalt chloride, and nickel chloride.

[0035] The concentration of the metal salt catalyst solution is 0.05~0.5 mol / L.

[0036] S2: Spread silica powder evenly on the bottom of a graphite crucible, place the carbonaceous substrate loaded with metal salt catalyst on the silica powder, and then perform heat treatment under an argon atmosphere to obtain ultralong SiC nanowires on the surface of the carbonaceous substrate.

[0037] The above process is as follows: Weigh 1~10 g of silica powder and spread it evenly at the bottom of a graphite crucible; place a carbonaceous substrate loaded with a metal salt catalyst on top of the silica powder; place the graphite crucible in an atmosphere sintering furnace, evacuate the furnace, and control the vacuum degree of the atmosphere sintering furnace to 0.1~0.4 Pa; then introduce argon gas into the atmosphere sintering furnace at a flow rate of 10~300 mL / min; then heat the atmosphere sintering furnace to 1300~1600 ℃ at a heating rate of 5~10 ℃ / min, and hold it at this temperature for 1~10 h; allow it to cool naturally to room temperature, and open the furnace to obtain ultralong SiC nanowires on the surface of the carbonaceous substrate, thus completing the preparation.

[0038] This invention proposes a method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder. The method employs low-cost SiO powder and utilizes a gas-liquid-solid reaction mechanism. The nanowires exhibit a 3C-SiC crystal structure with higher carrier mobility and greater stability. The SiO powder undergoes thermal evaporation at high temperature to form SiO gas, providing the silicon source, while the carbon elements in the carbonaceous substrate provide the carbon source. The carbonaceous substrate reacts with oxygen present in the system to generate CO gas. A metal salt catalyst decomposes into metal droplets at high temperature, adsorbing reactive gaseous precursors containing Si and C within the system. When the Si and C concentrations in the droplets become supersaturated, SiC nucleates and precipitates at the solid-liquid interface. With continuous supply of reactants, SiC continues to grow, ultimately forming one-dimensional ultralong nanowires. This invention achieves the growth of ultralong SiC nanowires on a carbonaceous substrate under ambient pressure, requiring minimal equipment, featuring a simple and controllable process, low raw material costs, good reproducibility, and broad application prospects.

[0039] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0040] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0041] Example 1 A method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powders is described below: S1: Carbon fiber cloth treatment: The carbon fiber cloth was washed with deionized water, anhydrous ethanol and acetone respectively and dried in an oven at 100℃ for 5 h. The dried carbon fiber cloth was then soaked in a 0.5 mol / L ferric nitrate / ethanol catalyst solution for 1 h, and then taken out and dried in an oven at 100℃ for 5 h. S2: Preparation of ultralong SiC nanowires on the surface of carbon fiber cloth: 1 g of silica powder was weighed and spread evenly at the bottom of a graphite crucible. Carbon fiber cloth loaded with ferric nitrate catalyst was placed on top of the silica powder. The graphite crucible was placed in an atmosphere sintering furnace, and a vacuum was drawn to control the vacuum degree of the atmosphere sintering furnace to 0.1 Pa. Argon gas was then introduced into the atmosphere sintering furnace at a flow rate of 10 mL / min. The atmosphere sintering furnace was then heated to 1450 ℃ at a heating rate of 5 ℃ / min and held at this temperature for 3 h. After naturally cooling to room temperature, the furnace was opened to obtain ultralong SiC nanowires on the surface of the carbon fiber cloth, thus completing the preparation.

[0042] Example 2 A method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powders is described below: S1: Carbon felt treatment: The carbon felt was washed with deionized water, anhydrous ethanol and acetone respectively and dried in a 70 ℃ oven for 24 h. The dried carbon felt was then soaked in a 0.05 mol / L cobalt nitrate / ethanol catalyst solution for 3 h, and then taken out and dried in a 70 ℃ oven for 24 h. S2: Preparation of ultralong SiC nanowires on carbon felt surface: 10 g of silica powder was weighed and spread evenly at the bottom of a graphite crucible. A carbon felt loaded with cobalt nitrate catalyst was placed on top of the silica powder. The graphite crucible was placed in an atmosphere sintering furnace, and a vacuum was drawn to control the vacuum degree of the atmosphere sintering furnace to 0.1 Pa. Argon gas was then introduced into the atmosphere sintering furnace at a flow rate of 100 mL / min. The atmosphere sintering furnace was then heated to 1600 ℃ at a heating rate of 10 ℃ / min and held at this temperature for 5 h. The furnace was then allowed to cool naturally to room temperature. Upon opening the furnace, ultralong SiC nanowires on the surface of the carbon felt were obtained, completing the preparation.

[0043] Example 3 A method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powders is described below: S1: Graphite sheet treatment: The graphite sheets were washed with deionized water, anhydrous ethanol and acetone respectively and dried in an oven at 70 ℃ for 24 h. The dried graphite sheets were then soaked in a 0.5 mol / L ferric nitrate / ethanol catalyst solution for 3 h, and then removed and dried in an oven at 70 ℃ for 24 h. S2: Preparation of ultralong SiC nanowires on graphite sheet surface: 10 g of silica powder was weighed and spread evenly at the bottom of a graphite crucible. A graphite sheet loaded with nickel nitrate catalyst was placed on top of the silica powder. The graphite crucible was placed in an atmosphere sintering furnace, and a vacuum was drawn to control the vacuum degree of the atmosphere sintering furnace to 0.1 Pa. Argon gas was then introduced into the atmosphere sintering furnace at a flow rate of 100 mL / min. The atmosphere sintering furnace was then heated to 1500 ℃ at a heating rate of 10 ℃ / min and held at this temperature for 4 h. The furnace was then allowed to cool naturally to room temperature. Upon opening the furnace, ultralong SiC nanowires on the surface of the graphite sheet were obtained, completing the preparation.

[0044] Example 4 A method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powders is described below: S1: Carbon paper treatment: The carbon paper was washed with deionized water, anhydrous ethanol and acetone respectively and dried in an 80 ℃ oven for 10 h. The dried carbon paper was then soaked in a 0.2 mol / L ferric nitrate / ethanol catalyst solution for 1 h, and then taken out and dried in an 80 ℃ oven for 10 h. S2: Preparation of ultralong SiC nanowires on carbon paper surface: 4 g of silica powder was weighed and spread evenly at the bottom of a graphite crucible. Carbon paper loaded with nickel nitrate catalyst was placed on top of the silica powder. The graphite crucible was placed in an atmosphere sintering furnace, and a vacuum was drawn to control the vacuum degree of the atmosphere sintering furnace to 0.1 Pa. Argon gas was then introduced into the atmosphere sintering furnace at a flow rate of 300 mL / min. The atmosphere sintering furnace was then heated to 1400 ℃ at a heating rate of 5 ℃ / min and held at this temperature for 10 h. After naturally cooling to room temperature, the furnace was opened to obtain ultralong SiC nanowires on the surface of the carbon paper, thus completing the preparation.

[0045] Example 5 A method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powders is described below: S1: Carbon fiber cloth treatment: The carbon fiber cloth was washed with deionized water, anhydrous ethanol and acetone respectively and dried in an oven at 100℃ for 5 h. The dried carbon fiber cloth was then soaked in a 0.5 mol / L ferric nitrate / ethanol catalyst solution for 1 h, and then taken out and dried in an oven at 100℃ for 5 h. S2: Preparation of ultralong SiC nanowires on the surface of carbon fiber cloth: 1 g of silica powder was weighed and spread evenly at the bottom of a graphite crucible. Carbon fiber cloth loaded with ferric nitrate catalyst was placed on top of the silica powder. The graphite crucible was placed in an atmosphere sintering furnace, and a vacuum was drawn to control the vacuum degree of the atmosphere sintering furnace to 0.1 Pa. Argon gas was then introduced into the atmosphere sintering furnace at a flow rate of 10 mL / min. The atmosphere sintering furnace was then heated to 1450 ℃ at a heating rate of 5 ℃ / min and held at this temperature for 3 h. After naturally cooling to room temperature, the furnace was opened to obtain ultralong SiC nanowires on the surface of the carbon fiber cloth, thus completing the preparation.

[0046] Example 6 A method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powders is described below: S1: Graphite paper treatment: The graphite paper was washed with deionized water, anhydrous ethanol and acetone respectively and dried in an oven at 70 ℃ for 24 h. The dried graphite paper was then immersed in a 0.1 mol / L nickel nitrate / ethanol catalyst solution for 1 h, and then removed and dried in an oven at 70 ℃ for 24 h. S2: Preparation of ultralong SiC nanowires on graphite paper surface: 5 g of silica powder was weighed and spread evenly at the bottom of a graphite crucible. Graphite paper loaded with cobalt nitrate catalyst was placed on top of the silica powder. The graphite crucible was placed in an atmosphere sintering furnace, and a vacuum was drawn to control the vacuum degree of the atmosphere sintering furnace to 0.1 Pa. Argon gas was then introduced into the atmosphere sintering furnace at a flow rate of 300 mL / min. The atmosphere sintering furnace was then heated to 1400 ℃ at a heating rate of 5 ℃ / min and held at this temperature for 5 h. The furnace was then allowed to cool naturally to room temperature. When the furnace was opened, ultralong SiC nanowires on the surface of graphite paper were obtained, completing the preparation.

[0047] This invention provides a method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder. The technical solution provided by this invention achieves uniform distribution of ultralong SiC nanowires on a carbonaceous matrix, resulting in large-area SiC nanowires. This technical solution utilizes low-cost inorganic powder raw materials, features simple and controllable processes and equipment, has strong versatility, and good reproducibility. This invention provides a simple technique and method for preparing ultralong SiC nanowires.

[0048] Figure 1The XRD pattern of the ultralong SiC nanowires prepared on the surface of carbon fiber cloth in Example 5 of this invention is shown. Analysis reveals that the characteristic diffraction peaks in the pattern highly match the standard card of cubic 3C-SiC, and the peaks are sharp and intense, indicating that the prepared SiC nanowires have a 3C-SiC crystal structure. Furthermore, the weak carbon (C) diffraction peaks detected in the pattern belong to the carbon fiber cloth substrate, further confirming that the product, apart from the substrate, is mainly composed of pure 3C-SiC phase, with no other obvious impurity peaks. This demonstrates that the preparation method can effectively achieve the controllable growth of high-purity 3C-SiC nanowires.

[0049] Figure 2 This is a low-magnification SEM image of the ultralong SiC nanowires on the carbon fiber fabric surface prepared in Example 5 of this invention. The image clearly shows that the prepared SiC nanowires exhibit significant ultralong characteristics, intertwining and forming a dense three-dimensional network structure with uniform nanowire morphology. The carbon fiber substrate is completely encapsulated and covered by these ultralong SiC nanowires, demonstrating good growth adhesion. The length of each individual nanowire is greater than 0.5 mm. This high aspect ratio microstructure not only confirms the realization of the ultralong characteristic but also provides a favorable structural basis for constructing a continuous conductive network and improving material properties.

[0050] Figure 3 This is a high-magnification SEM image of the ultralong SiC nanowires on the carbon fiber cloth surface prepared in Example 5 of this invention. The image clearly shows that the nanowires have a smooth and flat surface, a uniform diameter distribution ranging from 20 to 70 nm, exhibiting excellent one-dimensional nanostructure characteristics. Notably, distinct spherical catalyst particles can be observed at the tips of some nanowires, directly confirming that the growth of these SiC nanowires follows a gas-liquid-solid (VLS) mechanism. Combined with the foregoing description, these ultralong 3C-SiC nanowires with smooth surfaces and uniform diameters not only verify the reliability of the fabrication process but also provide microstructural support for their high carrier mobility applications in fields such as electronic devices.

[0051] In summary, the technical solution provided by this invention achieves uniform growth of ultralong 3C-SiC nanowires on carbon fiber cloth, resulting in nanowires with high stability and carrier mobility. This technical solution features low raw material costs, simple and controllable processes and equipment, strong versatility, and good reproducibility. This invention provides a novel technology and method for preparing ultralong SiC nanowires.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder, characterized in that, Includes the following steps: S1: After cleaning and drying the carbonaceous substrate, it is immersed in a metal salt catalyst solution to obtain a carbonaceous substrate loaded with a metal salt catalyst. S2: Spread silica powder evenly on the bottom of a graphite crucible, place the carbonaceous substrate loaded with metal salt catalyst on the silica powder, and then perform heat treatment under an argon atmosphere to obtain ultralong SiC nanowires on the surface of the carbonaceous substrate.

2. The method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder according to claim 1, characterized in that, In step S1, the carbon substrate is cleaned and dried. Specifically, the carbon substrate is cleaned with deionized water, anhydrous ethanol and acetone, and then placed in an oven to dry at 70~100℃ for 5~24 h.

3. The method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder according to claim 1, characterized in that, In step S1, the concentration of the metal salt catalyst solution is 0.05~0.5 mol / L; the soaking time is 1~4 h.

4. The method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder according to claim 1, characterized in that, In step S1, after soaking in a metal salt catalyst solution, the substrate is dried at 70~100 °C for 5~24 h to obtain a carbonaceous substrate supported on a metal salt catalyst.

5. The method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder according to claim 1, characterized in that, The carbon substrate is one of carbon fiber cloth, graphite sheet, graphite paper, carbon paper, and carbon felt.

6. The method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder according to claim 1, characterized in that, The metal salt catalyst solution is one of ferric nitrate, cobalt nitrate, nickel nitrate, ferrous sulfate, cobalt sulfate, nickel sulfate, ferric chloride, cobalt chloride, and nickel chloride.

7. A method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder according to claim 1, characterized in that, In step S2, the carbonaceous substrate loaded with the metal salt catalyst is placed on 1~10 g of silica powder.

8. A method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder according to claim 1, characterized in that, In step S2, the heating rate during the heat treatment process is 5~10 ℃ / min.

9. A method for preparing ultralong SiC nanowires on a carbonaceous substrate using inorganic powder according to claim 1, characterized in that, In step S2, the heat treatment process is carried out at a temperature of 1300~1600℃ for 1~10 h.

10. An ultralong SiC nanowire, characterized in that, It is prepared by the method described in any one of claims 1 to 9.

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