A method for synthesizing 3c-sic

Abstract

The application discloses a synthesis method of 3C phase SiC, which comprises the following steps: mixing SiC powder, oleic acid and ethanol, and ball milling to obtain the 3C phase SiC. The synthesis method of the 3C phase SiC can be carried out at room temperature in an atmospheric environment, and the synthesis method avoids the previous high-temperature synthesis method, and is easy to scale up.

Description

Technical Field

[0001] This invention relates to the field of materials preparation technology, and in particular to a method for synthesizing 3C phase SiC. Background Technology

[0002] Silicon carbide (SiC) possesses unique chemical and physical properties, such as hardness and mechanical stability, good thermal conductivity and a low coefficient of thermal expansion at high temperatures, and high corrosion and oxidation resistance. Due to the diversity of silicon carbide polymorphisms, the cubic nC-SiC structure is usually referred to as β-SiC, while all non-cubic structures (nH-SiC and nR-SiC) are generally classified as α-SiC. Silicon carbide polymorphs exhibit similar mechanical and thermal properties but show distinct bandgap energies and electronic characteristics. In particular, unlike other common semiconductors, the SiC configuration varies significantly, from 2.4 eV for 3C-SiC to over 3 eV for the 4H and 6H polymorphisms. The wide bandgap makes silicon carbide a very attractive semiconductor for optoelectronic devices, and β-silicon carbide is considered a suitable visible light absorbing material for photocatalytic applications.

[0003] However, in the research on β-SiC catalysis, most of the reported 3C phase SiCs need to be synthesized at high temperatures (>1200℃) and generally need to be synthesized in an inert atmosphere. The synthesis conditions are quite harsh, which limits its development. Summary of the Invention

[0004] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the object of the present invention is to provide a method for synthesizing 3C phase SiC.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for synthesizing 3C phase SiC includes the following steps: mixing SiC powder, oleic acid, and ethanol, and then ball milling the mixture to obtain the 3C phase SiC.

[0007] In some embodiments of the present invention, the mass-to-volume ratio of the SiC powder to the oleic acid is 1:0.8 to 1.5 g / mL; such as 1:1 g / mL, 1:1.1 g / mL, 1:1.2 g / mL, 1:1.3 g / mL, or 1:1.4 g / mL.

[0008] In some embodiments of the present invention, the mass-to-volume ratio of the SiC powder to the ethanol is 1:0.8 to 1.5 g / mL; such as 1:1 g / mL, 1:1.1 g / mL, 1:1.2 g / mL, 1:1.3 g / mL, or 1:1.4 g / mL.

[0009] In some embodiments of the present invention, the average particle size of the SiC powder is 500 nm to 3 mm, such as 800 nm, 1.0 μm, 10 μm, 100 μm, 1.0 mm, or 2.0 mm.

[0010] In some embodiments of the present invention, the average particle size of the 3C phase SiC is 80nm to 120nm; such as 90nm, 100nm, 110nm, etc.

[0011] In some embodiments of the present invention, the SiC powder is commercial SiC powder, that is, it includes α-SiC and / or β-SiC.

[0012] In some embodiments of the present invention, the rotational speed of the ball mill is 450 to 600 rpm; such as 480 rpm, 500 rpm, 550 rpm, etc.

[0013] In some embodiments of the present invention, the ball milling time is 24 to 48 hours, such as 30 hours, 36 hours, 45 hours, etc.

[0014] In some embodiments of the present invention, the ball mill rotation speed is controlled to increase at a rate of 200-400 rpm, such as 250 rpm, 300 rpm, or 350 rpm.

[0015] In some embodiments of the present invention, the ball milling is carried out at 18–35°C, such as at 20°C, 25°C, or 30°C; that is, ball milling can generally be carried out at room temperature.

[0016] In some embodiments of the present invention, the ball milling can be carried out in an atmospheric atmosphere, typically at 1 standard atmosphere.

[0017] In some embodiments of the present invention, the synthesis method of the 3C phase SiC further includes purifying the ball-milled product. The purification process includes sonicating the ball-milled product in water, allowing it to stand and separate into layers, taking the upper suspension, washing it 3-10 times with water and ethanol, and drying it at 50-80°C for 12-48 hours, such as 24 hours, 30 hours, 36 hours, or 45 hours. In this invention, after sonicating the ball-milled product in water and allowing it to stand, large particles settle to the lower layer, while small particles remain suspended in the upper layer. The upper layer is then washed multiple times to remove oleic acid, yielding purified 3C phase SiC.

[0018] In a second aspect, the present invention provides a method for synthesizing 3C phase SiC to obtain 3C phase SiC.

[0019] The beneficial effects of this invention are: the synthesis method of 3C phase SiC of this invention can be carried out at room temperature and in an atmospheric atmosphere, avoiding the need for high-temperature synthesis in the past, and is easy to scale up for production. Attached Figure Description

[0020] Figure 1 This is a scanning electron microscope image of commercial SiC according to the present invention.

[0021] Figure 2 This is a scanning electron microscope image of the 3C phase SiC obtained in Example 1 of the present invention.

[0022] Figure 3 This is a scanning electron microscope image of the 6H phase SiC prepared in Comparative Example 1 of this invention.

[0023] Figure 4 The image shows a transmission electron microscope (TEM) image of 3C phase SiC obtained in Example 1 of this invention, wherein the left and right images have different magnifications.

[0024] Figure 5 This is the EDS energy spectrum of 3C phase SiC obtained in Example 1 of the present invention.

[0025] Figure 6 The image shows the XRD diffraction pattern of 3C phase SiC obtained in Example 1 of this invention.

[0026] Figure 7 The preparation process and physical images of the products and corresponding XRD patterns of Embodiment 1 and Comparative Example 1 of the present invention are shown.

[0027] Figure 8 The images show the UV-Vis spectra of the products from Example 1 and Comparative Example 1 of this invention.

[0028] Figure 9 The results of photocatalytic performance testing of SiC prepared in Example 1 and Comparative Example 1 of this invention are shown.

[0029] Figure 10 The fluorescence spectra of the products of Example 1 and Comparative Example 1 of this invention are shown. Detailed Implementation

[0030] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0031] Example 1

[0032] This embodiment prepares a 3C phase SiC, and the specific process is as follows:

[0033] Commercial SiC powder (with an average particle size of approximately 1.0 μm, such as...) was used. Figure 1(As shown), oleic acid and ethanol are mixed evenly at a ratio of 1g:1mL:1mL and then added to a ball mill. The milling speed is controlled and increased from 200-400 rpm to 450-600 rpm. The ball milling is performed for 24 hours. The resulting sample is placed in 100mL of ultrapure water and sonicated for 1 hour. After separation, it is allowed to stand for 6 hours. 5mL of the upper layer solution is taken; it is washed 7 times with water and ethanol, and then dried in an oven at 60℃ for 24 hours. Figure 2 As shown, 3C phase SiC with an average particle size of approximately 100 nm was obtained.

[0034] Comparative Example 1

[0035] This comparative example prepared a SiC, which differs from Example 1 in that it did not contain oil acid. Figure 3 As shown, 6H phase SiC with an average particle size of approximately 600 nm was obtained.

[0036] Test case

[0037] Figures 4-6 Transmission electron microscopy (TEM) image, energy dispersive spectroscopy (EDS) spectrum, and XRD diffraction pattern of the 3C-phase SiC obtained in Example 1 are shown. It can be seen that the substance synthesized in Example 1 contains C and Si, corresponding to silicon carbide elements. The peak positions obtained from XRD diffraction, combined with the corresponding PDF cards, confirm that the synthesized compound is 3C-phase silicon carbide.

[0038] Figure 7 The preparation processes and product images and corresponding XRD patterns of Example 1 and Comparative Example 1 are shown. It can be seen that the SiC conformations obtained during ball milling are different with and without the addition of oleic acid; Comparative Example 1 yields 6H phase SiC.

[0039] The SiC samples prepared in Example 1 and Comparative Example 1 were subjected to UV-Vis spectroscopy. The specific procedure was as follows: 40 mg of barium sulfate was dissolved in 20 mL of water, and the barium sulfate was filtered onto filter paper. Then, 5 mg of the sample to be tested was dissolved in 20 mL of water and filtered onto the barium sulfate filter paper obtained in the previous step. After drying for 24 hours, the UV-Vis absorption of the sample was measured using UV-Vis spectroscopy. The results are as follows: Figure 8 As shown, in the ultraviolet-visible range, the 3C phase SiC prepared in Example 1 has better light absorption performance than the 6H phase SiC prepared in Comparative Example 1.

[0040] The photocatalytic performance of SiC prepared in Example 1 and Comparative Example 1 was tested. The specific procedure was as follows: 30 mg of photocatalyst and 20 mL of aqueous solution were added to a 400 mL gas-sealed glass reactor. The reaction vessel was evacuated. A 300 W xenon lamp was used as the light source. During the photocatalytic process, the reaction system was vigorously stirred with a magnetic stirrer. After each reaction, the product was quantified by GC (GC2019, 7920-TF2A, China). Other reaction conditions were the same as for typical reactions. The results are as follows: Figure 9 As shown, in the ultraviolet-visible range, the 3C phase SiC prepared in Example 1 has better photocatalytic hydrogen evolution performance than the 6H phase SiC prepared in Comparative Example 1.

[0041] 100 mg of the sample was taken for fluorescence testing. The fluorescence spectra of SiC prepared in Example 1 and Comparative Example 1 are as follows: Figure 10 As shown, the sample without oleic acid exhibits extremely strong fluorescence, reaching a maximum intensity of 14 WLU, while the 3C phase sample with oleic acid only shows a fluorescence of 2800 LU. In photocatalysis, the lower the fluorescence, the more suitable it is for photocatalytic reactions, proving that the 3C phase SiC has better performance.

[0042] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for synthesizing 3C phase SiC, characterized in that: Includes the following steps: The 3C phase SiC is prepared by ball milling a mixture of SiC powder, oleic acid, and ethanol. The mass-to-volume ratio of SiC powder to oleic acid is 1:0.8~1.5 g / mL. The ball milling speed is 450~600 rpm. The average particle size of the 3C phase SiC is 80 nm~120 nm.

2. The method for synthesizing 3C phase SiC according to claim 1, characterized in that: The mass-to-volume ratio of the SiC powder to the oleic acid is 1:1~1.4 g / mL.

3. The method for synthesizing 3C phase SiC according to claim 1, characterized in that: The mass-to-volume ratio of the SiC powder to the ethanol is 1:0.8~1.5 g / mL.

4. The method for synthesizing 3C phase SiC according to claim 1, characterized in that: The average particle size of the SiC powder is 500 nm to 3 mm.

5. The method for synthesizing 3C phase SiC according to claim 1, characterized in that: The ball mill rotates at a speed of 480-550 rpm; the ball milling time is 24-48 hours.

6. The method for synthesizing 3C phase SiC according to claim 1, characterized in that: The ball milling was carried out at 18~35℃.

7. The method for synthesizing 3C phase SiC according to claim 1, characterized in that: The ball milling was carried out in an atmospheric environment.

8. The method for synthesizing 3C phase SiC according to claim 1, characterized in that: The synthesis method of 3C phase SiC also includes purifying the ball-milled product. The purification process includes washing the ball-milled product with water and ethanol 3 to 7 times and drying it at 50 to 80°C for 12 to 48 hours.

9. 3C phase SiC prepared by the synthesis method of 3C phase SiC according to any one of claims 1 to 8.

10. The 3C phase SiC according to claim 9, characterized in that: The average particle size of the 3C phase SiC is 80nm~120nm.

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