Silicon carbide nano material as well as preparation method and application thereof

Abstract

The invention discloses a silicon carbide nano material as well as a preparation method and application thereof, and belongs to the technical field of functional materials. The silicon carbide nano material is composed of silicon carbide nanowires and nano particles; the silicon carbide is composed of rhombohedral SiC and is of a single-crystal structure with the same crystal lattice direction. The diameter of the nanowire is 30-400 nm, and the length of the nanowire is larger than 10 microns. The preparation method of the silicon carbide nano electrode material comprises the following steps: mixing chicken manure, silica sol and distilled water, adding the mixture into a sealed container, keeping the temperature at 80-150 DEG C for 1-5 hours, cooling and drying to obtain a precursor of chicken manure silicon dioxide; the preparation method comprises the following steps: fully mixing a precursor of chicken manure silicon dioxide with calcium chloride and sodium chloride, then putting the mixture into a crucible, putting the crucible into a vacuum reaction furnace, and carrying out heat preservation for 1-3 hours at the temperature of 800-1000 DEG C under the protection of nitrogen, so as to obtain the silicon carbide nano material. The two-step synthesis process is adopted, the synthesis process is easy to control, and meanwhile agricultural organic waste is turned into wealth. As an electrode material, the prepared silicon carbide nano material has a good application prospect in the aspect of electrocatalytic detection of heavy metal ions.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials, and in particular relates to a silicon carbide nanomaterial, a preparation method thereof, and an application thereof in electrocatalytic detection of heavy metal ions. Background Art

[0002] Chicken manure is an important agricultural organic waste, containing crude protein, fat, ash, carbohydrates, fiber, nitrogen, phosphorus, potassium and heavy metal ions such as copper and cadmium, as well as parasites, eggs and bacteria. It emits a foul odor, attracts pests and rodents, and pollutes the soil and water sources, causing soil eutrophication, thus causing serious environmental pollution. Therefore, converting chicken manure into high-value materials is of great research significance for the comprehensive utilization of agricultural organic waste and environmental protection.

[0003] The preparation of carbon-containing organic waste such as chicken manure into carbon-containing nanomaterials has aroused people's research interest. Nano silicon carbide is an important high-value carbon-containing nanomaterial with high hardness, high temperature resistance, high strength, corrosion resistance, friction resistance, good optical, semiconductor and catalytic properties. It has a wide range of applications in ceramics, mechanical engineering, refractory materials, semiconductors and catalysis. The national invention patent "A silicon carbide nanomaterial and its preparation method" (national invention patent number: ZL201910218578.7) discloses a silicon carbide nanomaterial and its preparation method. This method first dries the silicon monoxide and carbon nanotube dispersion to obtain a precursor, prepares a silicon carbide / carbon nanotube composite under vacuum of 0.03-0.1MPa and temperature of 1000-1400℃, and then calcines the silicon carbide / carbon nanotube composite under air or oxygen to obtain a silicon carbide nanobelt. The national invention patent "A method for preparing silicon carbide nanowires" (national invention patent number: ZL200510028034.2) reports a method for preparing silicon carbide nanowires. This method is to prepare hexamethylsilazane, hexamethyldisilane or polydimethylsilane at 1000-1100°C for 1-3 hours under the protection of inert gas. The national invention patent "Method for preparing silicon carbide nanowires" (national invention patent number: ZL200810017225.2) reports a method for preparing silicon carbide nanowires. This method is to mix ferrocene ethanol solution, silicon dioxide, silicon powder and graphite, and prepare silicon carbide nanowires at 1300-1800°C for 1-4 hours under the protection of argon. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a silicon carbide nanomaterial and a preparation method thereof that can be well applied in the electrocatalytic detection of heavy metal ions, so that the preparation process is easy to control and has good repeatability, and at the same time can realize the transformation of agricultural organic waste into treasure.

[0005] The present invention is achieved through the following technical solutions.

[0006] The present invention provides a silicon carbide nanomaterial, which is composed of silicon carbide nanowires and nanoparticles. The diameter of the nanowires is 30-400nm and the length is greater than 10μm. The silicon carbide is composed of rhombohedral SiC, which is a single crystal structure with the same lattice direction.

[0007] The present invention also provides a method for preparing the above silicon carbide nanomaterial, which specifically comprises the following steps:

[0008] (1) chicken manure, silica sol and distilled water are mixed, added into a sealed container, kept at 80-150° C. for 1-5 hours, cooled and dried to obtain a precursor of chicken manure silica;

[0009] (2) fully mixing the chicken manure silica precursor with calcium chloride and sodium chloride, then putting the mixture into a crucible, placing the crucible in a vacuum reaction furnace, and keeping the temperature at 800-1000° C. for 1-3 hours under nitrogen protection;

[0010] (3) After the reactor was naturally cooled to room temperature, distilled water was added to remove calcium chloride and sodium chloride in the sample, and the sample was calcined at 500°C for 5 h in an air atmosphere to obtain silicon carbide nanomaterials.

[0011] The solid content of the silica sol is 30%; the chicken manure accounts for 20-50% of the weight of the silica sol; the total weight of the chicken manure and the silica sol accounts for 20-40% of the weight of water; the molar ratio of calcium chloride to sodium chloride is 1:1; the total weight of the chicken manure and the silica sol accounts for 20-40% of the weight of calcium chloride and sodium chloride.

[0012] Furthermore, the chicken manure accounts for 35% of the weight of the silica sol; the total weight of the chicken manure and the silica sol accounts for 30% of the weight of water; the total weight of the chicken manure and the silica sol accounts for 30% of the weight of calcium chloride and sodium chloride.

[0013] The above silicon carbide nanomaterials can be used as nanoelectrode materials in the electrocatalytic detection of heavy metal ions.

[0014] Furthermore, the heavy metal ion is Hg 2+ , Pb 2+ or Cd 2+ .

[0015] The scientific principle of the present invention is speculated as follows:

[0016] The present invention adopts the above-mentioned synthesis process, firstly, heat treatment is carried out under the condition of 80-150° C. and heat preservation for 1-5 hours in a sealed state to obtain a uniform chicken manure silicon dioxide precursor, and then the chicken manure silicon dioxide precursor is reacted in a molten salt at 800-1000° C. for 1-3 hours under the protection of inert gas nitrogen, carbon in the chicken manure silicon dioxide precursor reacts with silicon dioxide to form silicon carbide crystal nuclei, and silicon carbide nanowires are formed through an oxide-assisted growth mechanism, and at the same time, due to the presence of metal elements such as copper and cadmium in the chicken manure, metals such as copper and cadmium also play an important role in the formation of silicon carbide nanowires through a gas-liquid-solid growth mechanism.

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] 1. The present invention adopts a two-step synthesis process, which is easy to control and has good repeatability, thus providing conditions for the practical application of silicon carbide nanomaterials.

[0019] 2. The raw materials used in the present invention are chicken manure, silica sol and water, which can transform agricultural organic waste chicken manure into high-value silicon carbide nanomaterials, thus turning waste into treasure.

[0020] 3. The silicon carbide nanomaterial prepared by the present invention has a large number of active sites, good small size effect, nano surface effect, good chemical and thermal stability, and good electrocatalytic properties. When the heavy metal ion concentration is 0.01–1000 μM (Hg 2+ )、0.001–100 μM(Pb 2+ ) and 0.01–1000 μM (Cd 2+ ) range, and its detection limit was as low as 1.18nM (Hg 2+ )、0.79nM(Pb 2+ ) and 3.26nM(Cd 2+ ). Therefore, as a nanoelectrode material, it has good application prospects in the electrocatalytic detection of heavy metal ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The X-ray diffraction (XRD) pattern of the silicon carbide nanomaterial synthesized in Example 1;

[0022] According to the JCPDS PDF card, it can be retrieved that the obtained silicon carbide is composed of rhombohedral SiC (JCPDS card, card number: 65-8103).

[0023] Figure 2 A scanning electron microscope (SEM) image of the silicon carbide nanomaterial synthesized in Example 1;

[0024] It can be seen from the figure that the product is composed of silicon carbide nanowires and nanoparticles. The diameter of the nanowires is 30 to 400 nm and the length is greater than 10 μm.

[0025] Figure 3 Transmission electron microscope (TEM) image of the silicon carbide nanomaterial synthesized in Example 1 ( Figure 3 (a)) and high-resolution TEM (HRTEM) images ( Figure 3 (b));

[0026] It can be seen from the figure that the product is composed of silicon carbide nanowires and nanoparticles. The diameter of the nanowires is 30 to 400 nm ( Figure 3 (a)), silicon carbide has a single crystal structure with the same lattice direction ( Figure 3 (b)).

[0027] Figure 4 The silicon carbide nanomaterial synthesized in Example 1 was used as a glassy carbon electrode modification material to electrochemically detect different concentrations of Hg in 0.1M KCl solution. 2+ , Pb 2+ and Cd 2+ Square wave voltammetry curves (SWVs) (test conditions: solution pH 7, deposition potential -1.5 V, deposition time 120 s, standing time 60 s; the inset in the figure shows the SWV peak current and Hg 2+ , Pb 2+ and Cd 2+ concentration relationship curve);

[0028] from Figure 4 It can be seen that with the increase of Hg 2+ , Pb 2+ and Cd 2+ The intensity of SWV peak current increases significantly with the increase of Hg concentration. 2+ , Pb 2+ and Cd 2+ The concentration relationship curve shows that the heavy metal ion concentration is 0.01–1000 μM (Hg 2+ )、0.001–100 μM(Pb 2+ ) and 0.01–1000 μM (Cd 2+ ) range, and has a linear relationship with the SWV peak current, and its detection limit is as low as 1.18nM (Hg 2+ )、0.79nM(Pb 2+ ) and 3.26nM(Cd 2+ ). DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0030] Example 1

[0031] (1) chicken manure, silica sol and distilled water are mixed, wherein the solid content of the silica sol is 30%, the chicken manure accounts for 20% of the weight of the silica sol, and the total weight of the chicken manure and silica sol accounts for 20% of the weight of the water, and the mixture is added into a sealed container, kept at 80° C. for 1 hour, cooled and dried to obtain a chicken manure silica precursor;

[0032] (2) The chicken manure silica precursor is fully mixed with calcium chloride and sodium chloride, wherein the molar ratio of calcium chloride to sodium chloride is 1:1, and the total weight of chicken manure and silica sol accounts for 20% of the weight of calcium chloride and sodium chloride. Then, the mixture is put into a crucible, and the crucible is placed in a vacuum reaction furnace under nitrogen protection at a temperature of 800°C for 1 hour;

[0033] (3) After the reactor was naturally cooled to room temperature, distilled water was added to remove calcium chloride and sodium chloride in the sample, and the sample was calcined at 500°C for 5 h in an air atmosphere to obtain silicon carbide nanomaterials.

[0034] Example 2

[0035] (1) chicken manure, silica sol and distilled water are mixed, wherein the solid content of the silica sol is 30%, the chicken manure accounts for 50% of the weight of the silica sol, and the total weight of the chicken manure and silica sol accounts for 40% of the weight of the water, and the mixture is added into a sealed container, kept at 150° C. for 5 hours, cooled and dried to obtain a chicken manure silica precursor;

[0036] (2) The precursor of chicken manure silica is fully mixed with calcium chloride and sodium chloride, wherein the molar ratio of calcium chloride to sodium chloride is 1:1, and the total weight of chicken manure and silica sol accounts for 40% of the weight of calcium chloride and sodium chloride. Then, the mixture is put into a crucible, and the crucible is placed in a vacuum reaction furnace under nitrogen protection at a temperature of 1000° C. for 3 hours;

[0037] (3) After the reactor was naturally cooled to room temperature, distilled water was added to remove calcium chloride and sodium chloride in the sample, and the sample was calcined at 500°C for 5 h in an air atmosphere to obtain silicon carbide nanomaterials.

[0038] Example 3

[0039] (1) chicken manure, silica sol and distilled water are mixed, wherein the solid content of the silica sol is 30%, the chicken manure accounts for 25% of the weight of the silica sol, and the total weight of the chicken manure and silica sol accounts for 25% of the weight of the water, and the mixture is added into a sealed container, kept at 90° C. for 2 hours, cooled and dried to obtain a chicken manure silica precursor;

[0040] (2) The chicken manure silica precursor is fully mixed with calcium chloride and sodium chloride, wherein the molar ratio of calcium chloride to sodium chloride is 1:1, and the total weight of chicken manure and silica sol accounts for 25% of the weight of calcium chloride and sodium chloride. Then the mixture is put into a crucible, and the crucible is placed in a vacuum reaction furnace under nitrogen protection at a temperature of 850°C for 1.5 hours;

[0041] (3) After the reactor was naturally cooled to room temperature, distilled water was added to remove calcium chloride and sodium chloride in the sample, and the sample was calcined at 500°C for 5 h in an air atmosphere to obtain silicon carbide nanomaterials.

[0042] Example 4

[0043] (1) chicken manure, silica sol and distilled water are mixed, wherein the solid content of the silica sol is 30%, the chicken manure accounts for 30% of the weight of the silica sol, and the total weight of the chicken manure and silica sol accounts for 30% of the weight of the water, and the mixture is added into a sealed container, kept at 100° C. for 2.5 hours, cooled and dried to obtain a chicken manure silica precursor;

[0044] (2) The chicken manure silica precursor is fully mixed with calcium chloride and sodium chloride, wherein the molar ratio of calcium chloride to sodium chloride is 1:1, and the total weight of chicken manure and silica sol accounts for 30% of the weight of calcium chloride and sodium chloride. Then, the mixture is loaded into a crucible, and the crucible is placed in a vacuum reaction furnace under nitrogen protection at a temperature of 900°C for 2 hours;

[0045] (3) After the reactor was naturally cooled to room temperature, distilled water was added to remove calcium chloride and sodium chloride in the sample, and the sample was calcined at 500°C for 5 h in an air atmosphere to obtain silicon carbide nanomaterials.

[0046] Example 5

[0047] (1) chicken manure, silica sol and distilled water are mixed, wherein the solid content of the silica sol is 30%, the chicken manure accounts for 35% of the weight of the silica sol, and the total weight of the chicken manure and silica sol accounts for 35% of the weight of the water, and the mixture is added into a sealed container, kept at 110° C. for 3 hours, cooled and dried to obtain a chicken manure silica precursor;

[0048] (2) The chicken manure silica precursor is fully mixed with calcium chloride and sodium chloride, wherein the molar ratio of calcium chloride to sodium chloride is 1:1, and the total weight of chicken manure and silica sol accounts for 35% of the weight of calcium chloride and sodium chloride. Then the mixture is put into a crucible, and the crucible is placed in a vacuum reaction furnace under nitrogen protection at a temperature of 950°C for 2.5 hours;

[0049] (3) After the reactor was naturally cooled to room temperature, distilled water was added to remove calcium chloride and sodium chloride in the sample, and the sample was calcined at 500°C for 5 h in an air atmosphere to obtain silicon carbide nanomaterials.

[0050] Example 6

[0051] (1) chicken manure, silica sol and distilled water are mixed, wherein the solid content of the silica sol is 30%, the chicken manure accounts for 40% of the weight of the silica sol, and the total weight of the chicken manure and silica sol accounts for 30% of the weight of the water, and the mixture is added into a sealed container, kept at 120° C. for 3.5 hours, cooled and dried to obtain a chicken manure silica precursor;

[0052] (2) The chicken manure silica precursor is fully mixed with calcium chloride and sodium chloride, wherein the molar ratio of calcium chloride to sodium chloride is 1:1, and the total weight of chicken manure and silica sol accounts for 30% of the weight of calcium chloride and sodium chloride. Then, the mixture is put into a crucible, and the crucible is placed in a vacuum reaction furnace under nitrogen protection at a temperature of 1000° C. for 2.5 hours;

[0053] (3) After the reactor was naturally cooled to room temperature, distilled water was added to remove calcium chloride and sodium chloride in the sample, and the sample was calcined at 500°C for 5 h in an air atmosphere to obtain silicon carbide nanomaterials.

[0054] Example 7

[0055] (1) chicken manure, silica sol and distilled water are mixed, wherein the solid content of the silica sol is 30%, the chicken manure accounts for 45% of the weight of the silica sol, and the total weight of the chicken manure and silica sol accounts for 25% of the weight of the water, and the mixture is added into a sealed container, kept at 130° C. for 4 hours, cooled and dried to obtain a chicken manure silica precursor;

[0056] (2) The chicken manure silica precursor is fully mixed with calcium chloride and sodium chloride, wherein the molar ratio of calcium chloride to sodium chloride is 1:1, and the total weight of chicken manure and silica sol accounts for 25% of the weight of calcium chloride and sodium chloride. Then the mixture is put into a crucible, and the crucible is placed in a vacuum reaction furnace under nitrogen protection at a temperature of 950°C for 3 hours;

[0057] (3) After the reactor was naturally cooled to room temperature, distilled water was added to remove calcium chloride and sodium chloride in the sample, and the sample was calcined at 500°C for 5 h in an air atmosphere to obtain silicon carbide nanomaterials.

[0058] Example 8

[0059] (1) chicken manure, silica sol and distilled water are mixed, wherein the solid content of the silica sol is 30%, the chicken manure accounts for 40% of the weight of the silica sol, and the total weight of the chicken manure and silica sol accounts for 20% of the weight of the water, and the mixture is added into a sealed container, kept at 140° C. for 4.5 hours, cooled and dried to obtain a chicken manure silica precursor;

[0060] (2) The chicken manure silica precursor is fully mixed with calcium chloride and sodium chloride, wherein the molar ratio of calcium chloride to sodium chloride is 1:1, and the total weight of chicken manure and silica sol accounts for 20% of the weight of calcium chloride and sodium chloride. Then, the mixture is put into a crucible, and the crucible is placed in a vacuum reaction furnace under nitrogen protection at a temperature of 900° C. for 2 hours;

[0061] (3) After the reactor was naturally cooled to room temperature, distilled water was added to remove calcium chloride and sodium chloride in the sample, and the sample was calcined at 500°C for 5 h in an air atmosphere to obtain silicon carbide nanomaterials.

Claims

1. A silicon carbide nanomaterial, characterized in that: The silicon carbide nanomaterial is composed of silicon carbide nanowires and nanoparticles; the silicon carbide is composed of rhombohedral SiC, which is a single crystal structure with the same lattice direction; the diameter of the nanowire is 30-400nm and the length is greater than 10μm.

2. A method for preparing a silicon carbide nanomaterial as claimed in claim 1, characterized in that The steps include: (1) chicken manure, silica sol and distilled water are mixed, added into a sealed container, kept at 80-150° C. for 1-5 hours, cooled and dried to obtain a precursor of chicken manure silica; (2) fully mixing the chicken manure silica precursor with calcium chloride and sodium chloride, then putting the mixture into a crucible, placing the crucible in a vacuum reaction furnace, and keeping the temperature at 800-1000° C. for 1-3 hours under nitrogen protection; (3) After the reactor was naturally cooled to room temperature, distilled water was added to remove calcium chloride and sodium chloride in the sample, and the sample was calcined at 500 °C for 5 h in an air atmosphere to obtain silicon carbide nanomaterials; The solid content of the silica sol is 30%; The chicken manure accounts for 20 to 50% of the weight of the silica sol; The total weight of the chicken manure and silica sol accounts for 20-40% of the weight of water; The molar ratio of calcium chloride to sodium chloride is 1:1; The total weight of the chicken manure and silica sol accounts for 20-40% of the weight of the calcium chloride and the sodium chloride.

3. The method for preparing silicon carbide nanomaterials according to claim 2, characterized in that: The chicken manure accounts for 35% of the weight of the silica sol; The total weight of the chicken manure and silica sol accounts for 30% of the weight of water; The total weight of the chicken manure and silica sol accounts for 30% of the weight of calcium chloride and sodium chloride.

4. Use of the silicon carbide nanomaterial as claimed in claim 1 as a nanoelectrode material in electrocatalytic detection of heavy metal ions.

5. The use of the silicon carbide nanomaterial as claimed in claim 4 as a nanoelectrode material in electrocatalytic detection of heavy metal ions, characterized in that: The heavy metal ion is Hg 2+ , Pb 2+ or Cd 2+ .

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