Sea urchin-shaped nitrogen-doped SiC nanowire clusters on graphite paper surface and preparation method thereof

Abstract

The present invention relates to a sea urchin-shaped nitrogen-doped SiC nanowire cluster on the surface of graphite paper and a preparation method thereof. By changing process parameters such as the mass ratio of polycarbosilane to a nitrogen source, the type of nitrogen source, and the heat treatment temperature, sea urchin-shaped nitrogen-doped SiC nanowire clusters are prepared on the surface of graphite paper. The SiC nanowires prepared by the present invention have a conical shape with a fluctuating diameter and a sharp and clear tip, and are in situ grown on the surface of graphite paper to form sea urchin-shaped SiC nanowire clusters, while achieving the effect of large-scale, reproducible in situ growth of sea urchin-shaped nitrogen-doped SiC nanowire clusters. The method is simple to operate, has a controllable process, and is highly reproducible. The prepared nitrogen-doped SiC nanowires have a high aspect ratio, high yield, and high purity. This method provides a new technology and method for the in situ growth of sea urchin-shaped SiC nanowire clusters, and is expected to be widely used in the fields of energy storage and conversion, field emitters, composite materials, nano-reinforcements, and photodetectors.

Description

Technical Field

[0001] The invention belongs to the field of preparation of SiC nanowires and relates to a sea urchin-shaped nitrogen-doped SiC nanowire cluster on the surface of graphite paper and a preparation method thereof. Background Art

[0002] SiC nanowires have a range of advantages, including high aspect ratio and specific surface area, high thermal and electrical conductivity, high thermal and chemical stability, and excellent mechanical properties. They have attracted widespread attention in fields such as energy storage and conversion, field emitters, composite materials, nanoreinforcements, and photodetectors. Furthermore, research has shown that compared with conventional linear nanostructures with a single diameter, SiC one-dimensional nanostructures with fluctuating diameters (such as beaded, inverted cone, and bamboo-like structures) are expected to exhibit superior performance in these areas. Reference 1, "Zhang M, Zhao J, Li Z, et al. Bamboo-like 3C-SiC nanowires with periodic fluctuating diameter: Homogeneous synthesis, synergistic growth mechanism, and their luminescence properties [J]. Journal of Solid State Chemistry, 2016, 243: 247-252," reported that bamboo-like 3C-SiC nanowires with fluctuating diameters were prepared on a 6H-SiC substrate via a chemical vapor reaction process. The prepared SiC nanowires exhibit good photoluminescence properties due to their nanometer-scale diameter and high-density defects inside the fluctuating diameter. However, the SiC nanowires prepared by this method are randomly oriented and flat on the substrate surface, which greatly limits the application potential of SiC nanowires. In addition, relevant studies have shown that nitrogen doping is an effective way to improve the microwave absorption and field emission properties of SiC nanowires. Reference 2 "Chen S, Ying P, Wang L, et al. Highly flexible and robust N-doped SiC nanoneedle field emitters [J]. NPG Asia Materials, 2015, 7 (1): e157-e157." Nitrogen-doped SiC nanoneedles were synthesized on carbon fiber fabrics using a catalyst-assisted pyrolysis process. Although the sharp tips and nitrogen-doped characteristics of SiC nanoneedles give them good field emission properties, the volume ratio of nitrogen source (nitrogen) / carrier gas (argon) during the pyrolysis process is difficult to control, resulting in difficulty in controlling the nitrogen doping level of SiC nanowires and even producing impurities such as silicon nitride nanowires, reducing the purity of the product. Therefore, there is an urgent need to develop a simple and effective preparation method to achieve the controllable preparation of SiC nanostructures with special morphology and adjustable nitrogen doping level.

[0003] The present invention prepares sea urchin-shaped nitrogen-doped SiC nanowire clusters on the surface of graphite paper through a simple catalyst-assisted polymer precursor cracking process and a controllable nitrogen doping method. The prepared SiC nanowires have a conical shape with a fluctuating diameter and a sharp and clear tip. The method is simple to operate, the process is controllable, and the repeatability is strong, which is conducive to promotion to large-scale preparation. The prepared nitrogen-doped SiC nanowires have a high aspect ratio, high yield, and high purity, providing a new technology and method for the in situ growth of sea urchin-shaped nitrogen-doped SiC nanowire clusters on the substrate surface. At the same time, due to its special structure with fluctuating diameter and sharp tip, as well as controllable nitrogen doping level, the prepared SiC nanowires are believed to have broad application potential in the fields of energy storage and conversion, field emitters, composite materials, nano-reinforcements and photodetectors. Summary of the Invention

[0004] Technical problems to be solved

[0005] In order to avoid the shortcomings of the prior art, the present invention proposes a sea urchin-shaped nitrogen-doped SiC nanowire cluster on the surface of graphite paper and a preparation method thereof, which uses organic polycarbosilane (PCS) to provide a silicon source, uses a metal salt ethanol solution as a catalyst, and prepares sea urchin-shaped nitrogen-doped SiC nanowire clusters on the surface of graphite paper by high-temperature pyrolysis of the precursor. This technical solution is simple to operate, has a controllable process, strong repeatability, high yield, and high purity. The prepared nitrogen-doped SiC nanowires have a conical shape with a fluctuating diameter and a sharp and clear tip, and a high aspect ratio. At the same time, compared with randomly oriented SiC nanowires, the sea urchin-shaped nitrogen-doped SiC nanowire clusters prepared by the present invention may exhibit excellent bonding strength and structural stability with the substrate due to their in-situ directional growth on the substrate.

[0006] Technical Solution

[0007] A method for preparing sea urchin-shaped nitrogen-doped SiC nanowire clusters on the surface of graphite paper, characterized by the following steps:

[0008] Step 1: Substrate treatment: spray the metal salt ethanol solution on the surface of the dried graphite paper, and then place the catalyst-loaded graphite paper in an oven for drying;

[0009] Step 2, powder mixing: ball milling polycarbosilane and nitrogen source powder in a mass ratio of 5:1 to 1:5 to obtain a fine and uniformly mixed powder, which is then taken out and placed in an oven for drying;

[0010] Step 3: Synthesis of sea urchin-shaped SiC nanowire clusters: The mixed powder from step 2 was spread on the bottom of an alumina crucible, and the catalyst-loaded graphite paper from step 1 was suspended above the crucible. The alumina crucible was then placed in the heat treatment zone of a tube furnace. Under an argon atmosphere (flow rate of 20-200 mL / min), the temperature was first raised to 240-300°C at a rate of 5-10°C / min and held for 0.5-1 hour. The temperature was then raised to 1400-1700°C and held for 1-3 hours. The power was turned off, the mixture was allowed to cool naturally to room temperature, and the graphite paper with sea urchin-shaped nitrogen-doped SiC nanowire clusters on its surface was removed.

[0011] The surface of the graphite paper is wiped with anhydrous ethanol and then placed in an oven for drying.

[0012] The drying in the oven in step 1 and step 2 is: in an oven at 60-100° C. for 5-24 hours.

[0013] The concentration of the metal salt ethanol solution is 0.02-1 mol / L.

[0014] The polycarbosilane and nitrogen source powder are ball-milled in the following steps: putting the polycarbosilane and nitrogen source powder into a planetary ball mill, and ball-milling them at a rotation speed of 150 to 200 rpm for 12 to 24 hours.

[0015] The metal salt solution in step 1 is one of, but not limited to, ferric nitrate, cobalt nitrate, nickel nitrate, ferrous sulfate, cobalt sulfate, nickel sulfate, ferric chloride, cobalt chloride, and nickel chloride.

[0016] The nitrogen source powder in step 2 is one of, but not limited to, dicyandiamide, melamine, urea, and hexamethylenetetramine.

[0017] The flow rate of the argon atmosphere in step 3 is 20 to 200 mL / min.

[0018] The nitrogen-doped SiC nanowires on the surface of graphite paper obtained by the method for preparing sea urchin-shaped nitrogen-doped SiC nanowire clusters on the surface of graphite paper are characterized in that the nitrogen-doped SiC nanowires on the surface of graphite paper are sea urchin-shaped nitrogen-doped SiC nanowire clusters, and the SiC nanowires have a conical shape with a fluctuating diameter and a sharp and clear tip.

[0019] The nitrogen-doped SiC nanowire has a length of 25 μm and an aspect ratio of more than 100.

[0020] Beneficial effects

[0021] The present invention proposes a method for preparing sea urchin-shaped nitrogen-doped SiC nanowire clusters on a graphite paper surface. This method utilizes a simple catalyst-assisted precursor cracking process and a controllable nitrogen doping method. By varying process parameters such as the mass ratio of polycarbosilane to nitrogen source, the type of nitrogen source, and the heat treatment temperature, sea urchin-shaped nitrogen-doped SiC nanowire clusters are produced on the graphite paper surface. The SiC nanowires produced by the present invention exhibit a tapered shape with fluctuating diameters and sharp, well-defined tips. The sea urchin-shaped SiC nanowire clusters are grown in situ on the graphite paper surface, achieving large-scale, reproducible in situ growth of sea urchin-shaped nitrogen-doped SiC nanowire clusters. This method is simple to operate, controllable, and highly reproducible. The resulting nitrogen-doped SiC nanowires exhibit a high aspect ratio, high yield, and high purity. This method provides a new technology and method for the in situ growth of sea urchin-shaped SiC nanowire clusters, and is expected to find widespread application in energy storage and conversion, field emitters, composite materials, nanoreinforcements, and photodetectors.

[0022] Figure 1 This is a flow chart for the preparation process of sea urchin-shaped nitrogen-doped SiC nanowire clusters on the surface of graphite paper. The flow chart clearly shows the preparation process proposed by the present invention. The preparation process is mainly divided into three steps and is simple to operate. Figure 2 The XRD pattern of the sea urchin-shaped nitrogen-doped SiC nanowire cluster prepared by the present invention shows that the main component of the prepared SiC nanowire is 3C-SiC. The peak of 3C-SiC is sharp, indicating that it has good crystallinity; the C peak detected in the XRD pattern comes from the graphite paper substrate. The microstructure of the sea urchin-shaped nitrogen-doped SiC nanowire cluster prepared by the present invention is as follows Figure 3 A large number of nanowire bundles were in situ grown on the graphite paper substrate in a cluster-like morphology, indicating that this preparation process can obtain high-yield nitrogen-doped SiC nanowires. Figure 4 This is a high-magnification SEM image of the sea urchin-shaped nitrogen-doped SiC nanowire clusters prepared by the present invention. As can be seen from the image, the nanowires prepared by the present invention have a tapered shape with fluctuating diameters and sharp, well-defined tips, with lengths up to 25 μm and aspect ratios exceeding 100. The technical solution, process, and equipment provided by the present invention are simple, controllable, and reproducible. The prepared nitrogen-doped SiC nanowires have a high aspect ratio, high yield, and high purity, providing a new technology and method for the preparation of sea urchin-shaped SiC nanowire clusters with broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 :A process flow chart for preparing sea urchin-shaped nitrogen-doped SiC nanowire clusters on graphite paper surface;

[0024] Figure 2 : XRD pattern of sea urchin-shaped nitrogen-doped SiC nanowire clusters prepared in the present invention;

[0025] Figure 3 : Low-magnification SEM characterization image of the sea urchin-shaped nitrogen-doped SiC nanowire clusters prepared in the present invention;

[0026] Figure 4 : High-magnification SEM characterization image of sea urchin-shaped nitrogen-doped SiC nanowire clusters prepared in the present invention; DETAILED DESCRIPTION

[0027] The present invention will now be further described with reference to the embodiments and accompanying drawings:

[0028] Example 1:

[0029] 1. Substrate treatment: Wipe the surface of the graphite paper with anhydrous ethanol and place it in an oven at 80°C for 6 hours until it is dry. Prepare a 0.05 mol / L iron nitrate ethanol solution and spray it on the dried graphite paper surface with a spray bottle. Then place the catalyst-loaded graphite paper in an oven at 80°C for 10 hours until it is dry.

[0030] 2. Powder mixing: Put polycarbosilane and melamine in a mass ratio of 1:1 into a planetary ball mill and ball mill at a speed of 150 rpm for 15 hours to obtain refined and evenly mixed powder. Then take it out and place it in an oven at 80°C for 18 hours until it is dried.

[0031] III. Synthesis of Sea Urchin-Shaped SiC Nanowire Clusters: Weigh 4 g of the mixed powder obtained in Step 2 and place it on the bottom of an alumina crucible. Suspend a catalyst-loaded graphite paper above the crucible. Place the crucible in the heat treatment zone of a tube furnace. Then, under an argon atmosphere (flow rate of 150 mL / min), heat the sample at a rate of 5°C / min to 280°C and hold for 1 hour. Next, heat the sample to 1500°C and hold for 1 hour. Turn off the power, allow the sample to cool naturally to room temperature, and remove the sample.

[0032] Example 2:

[0033] 1. Substrate treatment: Wipe the surface of the graphite paper with anhydrous ethanol and place it in an oven at 60°C for 10 hours until it is dry. Prepare a 0.1 mol / L iron nitrate ethanol solution and spray it on the dried graphite paper surface with a spray bottle. Then place the graphite paper loaded with catalyst in an oven at 60°C for 12 hours until it is dry.

[0034] 2. Powder mixing: Put polycarbosilane and dicyandiamide in a mass ratio of 1:1 into a planetary ball mill and ball mill at a speed of 180 rpm for 20 hours to obtain refined and evenly mixed powder. Then take it out and place it in an oven at 60°C for 15 hours until it is dried.

[0035] III. Synthesis of Sea Urchin-Shaped SiC Nanowire Clusters: Weigh 3 g of the mixed powder obtained in Step 2 and place it on the bottom of an alumina crucible. Suspend a catalyst-loaded graphite paper above the crucible. Place the crucible in the heat treatment zone of a tube furnace. Then, under an argon atmosphere (flow rate of 100 mL / min), heat the sample at a rate of 5°C / min to 300°C and hold for 0.5 h. Then, heat the sample to 1500°C and hold for 1 h. Turn off the power, allow the sample to cool naturally to room temperature, and remove the sample.

[0036] Example 3:

[0037] 1. Substrate treatment: Wipe the surface of the graphite paper with anhydrous ethanol and place it in an oven at 70°C for 8 hours until it is dry. Prepare a 0.1 mol / L cobalt nitrate ethanol solution and spray it on the dried graphite paper surface with a spray bottle. Then place the catalyst-loaded graphite paper in an oven at 70°C for 10 hours until it is dry.

[0038] 2. Powder mixing: Put polycarbosilane and melamine in a mass ratio of 2:1 into a planetary ball mill and ball mill at a speed of 180 rpm for 18 hours to obtain refined and evenly mixed powder. Then take it out and place it in an oven at 70°C for 14 hours until it is dried.

[0039] III. Synthesis of Sea Urchin-Shaped SiC Nanowire Clusters: Weigh 5g of the mixed powder obtained in Step 2 and place it on the bottom of an alumina crucible. Suspend a catalyst-loaded graphite paper above the crucible. Place the crucible in the heat treatment zone of a tube furnace. Then, under an argon atmosphere (50mL / min), heat the sample at a rate of 5°C / min to 300°C and hold for 1 hour. Next, heat the sample to 1600°C and hold for 1 hour. Turn off the power, allow the sample to cool naturally to room temperature, and remove the sample.

[0040] Example 4:

[0041] 1. Substrate treatment: Wipe the surface of the graphite paper with anhydrous ethanol and place it in a 70°C oven for 9 hours until it is dry. Prepare a 0.5 mol / L cobalt nitrate ethanol solution and spray it on the dried graphite paper surface with a spray bottle. Then place the catalyst-loaded graphite paper in a 70°C oven for 12 hours until it is dry.

[0042] 2. Powder mixing: Put polycarbosilane and dicyandiamide in a mass ratio of 2:1 into a planetary ball mill and mill at a speed of 200 rpm for 15 hours to obtain a refined and evenly mixed powder. Then take it out and place it in an oven at 70°C for 10 hours until it is dried.

[0043] III. Synthesis of Sea Urchin-Shaped SiC Nanowire Clusters: Weigh 4g of the mixed powder obtained in Step 2 and place it on the bottom of an alumina crucible. Suspend a catalyst-loaded graphite paper above the crucible. Place the crucible in the heat treatment zone of a tube furnace. Then, under an argon atmosphere (flow rate of 30mL / min), heat the sample at a rate of 10°C / min to 300°C and hold for 1 hour. Next, heat the sample to 1600°C and hold for 2 hours. Turn off the power, allow the sample to cool naturally to room temperature, and remove the sample.

[0044] Example 5:

[0045] 1. Substrate treatment: Wipe the surface of the graphite paper with anhydrous ethanol and place it in an oven at 80°C for 6 hours until it is dry. Prepare a 0.6 mol / L iron nitrate ethanol solution and spray it on the dried graphite paper surface with a spray bottle. Then place the graphite paper loaded with catalyst in an oven at 60°C for 15 hours until it is dry.

[0046] 2. Powder mixing: Put polycarbosilane and melamine in a mass ratio of 4:1 into a planetary ball mill and ball mill at a speed of 180 rpm for 12 hours to obtain refined and evenly mixed powder. Then take it out and place it in an oven at 60°C for 10 hours until it is dried.

[0047] III. Synthesis of Sea Urchin-Shaped SiC Nanowire Clusters: Weigh 3 g of the mixed powder obtained in Step 2 and place it on the bottom of an alumina crucible. Suspend a catalyst-loaded graphite paper above the crucible. Place the crucible in the heat treatment zone of a tube furnace. Then, under an argon atmosphere (flow rate of 180 mL / min), heat the sample at a rate of 5°C / min to 280°C and hold for 1 hour. Next, heat the sample to 1500°C and hold for 2 hours. Turn off the power, allow the sample to cool naturally to room temperature, and remove the sample.

[0048] Example 6:

[0049] 1. Substrate treatment: Wipe the surface of the graphite paper with anhydrous ethanol and place it in an oven at 80°C for 7 hours until it is dry. Prepare a 0.08 mol / L cobalt nitrate ethanol solution and spray it on the dried graphite paper surface with a spray bottle. Then place the catalyst-loaded graphite paper in an oven at 80°C for 10 hours until it is dry.

[0050] 2. Powder mixing: Put polycarbosilane and melamine in a mass ratio of 4:1 into a planetary ball mill and ball mill at a speed of 150 rpm for 20 hours to obtain refined and evenly mixed powder. Then take it out and place it in an 80°C oven for 8 hours until it is dried.

[0051] III. Synthesis of Sea Urchin-Shaped SiC Nanowire Clusters: Weigh 3 g of the mixed powder obtained in Step 2 and place it on the bottom of an alumina crucible. Suspend a catalyst-loaded graphite paper above the crucible. Place the crucible in the heat treatment zone of a tube furnace. Then, under an argon atmosphere (flow rate of 150 mL / min), heat the sample at a rate of 5°C / min to 300°C and hold for 0.8 h. Then, heat the sample to 1500°C and hold for 2 h. Turn off the power, allow the sample to cool naturally to room temperature, and remove the sample.

[0052] This invention proposes a method for preparing sea urchin-shaped nitrogen-doped SiC nanowire clusters on the surface of graphite paper. The technical solution provided by the invention is simple to operate, process-controllable, and highly reproducible, facilitating its application to large-scale production. The prepared nitrogen-doped SiC nanowires have a high aspect ratio, high yield, and high purity. This provides a new technology and method for the in situ growth of sea urchin-shaped nitrogen-doped SiC nanowire clusters on substrate surfaces, and is expected to find widespread application in fields such as energy storage and conversion, field emitters, composite materials, nanoreinforcements, and photodetectors.

[0053] The technical solution of the present invention is not limited to the specific embodiments listed above, and various modifications can be made. That is, all other embodiments obtained according to the claims and description of the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing sea urchin-shaped nitrogen-doped SiC nanowire clusters on the surface of graphite paper, characterized in that Here are the steps: Step 1: Substrate treatment: spray the metal salt ethanol solution on the surface of the dried graphite paper, and then place the catalyst-loaded graphite paper in an oven for drying; Step 2, powder mixing: ball milling polycarbosilane and nitrogen source powder in a mass ratio of 5:1 to 1:5 to obtain a fine and uniformly mixed powder, which is then taken out and placed in an oven for drying; Step 3, Synthesis of Sea Urchin-Shaped SiC Nanowire Clusters: Spread the mixed powder from step 2 on the bottom of an alumina crucible, and suspend the catalyst-loaded graphite paper from step 1 above the crucible. Place the alumina crucible in the heat treatment zone of a tube furnace. Then, under the protection of an argon atmosphere with a flow rate of 20-200 mL / min, heat the mixture to 240-300°C at a rate of 5-10°C / min, hold for 0.5-1 h, then heat the mixture to 1400-1700°C, and hold for 1-3 h. Turn off the power, cool the mixture naturally to room temperature, and remove the graphite paper with sea urchin-shaped nitrogen-doped SiC nanowire clusters on the surface. The concentration of the metal salt ethanol solution is 0.02~1 mol / L; The metal salt in the metal salt ethanol solution in step 1 is one of: ferric nitrate, cobalt nitrate, nickel nitrate, ferrous sulfate, cobalt sulfate, nickel sulfate, ferric chloride, cobalt chloride, and nickel chloride; The nitrogen source powder in step 2 is one of the following: dicyandiamide, melamine, urea, and hexamethylenetetramine.

2. The method for preparing sea urchin-shaped nitrogen-doped SiC nanowire clusters on the surface of graphite paper according to claim 1, characterized in that: The surface of the graphite paper is wiped with anhydrous ethanol and then placed in an oven for drying.

3. The method for preparing sea urchin-shaped nitrogen-doped SiC nanowire clusters on the surface of graphite paper according to claim 1 or 2, characterized in that: The drying in the oven in step 1 and step 2 is: in an oven at 60-100° C. for 5-24 hours.

4. The method for preparing sea urchin-shaped nitrogen-doped SiC nanowire clusters on the surface of graphite paper according to claim 1, characterized in that: The polycarbosilane and nitrogen source powder are ball milled as follows: the polycarbosilane and nitrogen source powder are placed in a planetary ball mill, and ball milled at a speed of 150-200 rpm for 12-24 hours.

5. Nitrogen-doped SiC nanowires on the surface of graphite paper obtained by the method for preparing sea urchin-shaped nitrogen-doped SiC nanowire clusters on the surface of graphite paper according to any one of claims 1 to 4, characterized in that: The nitrogen-doped SiC nanowires on the graphite paper surface are sea urchin-like nitrogen-doped SiC nanowire clusters, and the SiC nanowires have a conical shape with a fluctuating diameter and a sharp and clear tip.

6. The nitrogen-doped SiC nanowires on the surface of graphite paper according to claim 5, characterized in that: The nitrogen-doped SiC nanowires have a length of up to 25 μm and an aspect ratio of more than 100.

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