Preparation method of SiC powder particles with visible light response and high specific surface area

Abstract

The invention discloses a preparation method of SiC powder particles with visible-light response and high specific surface area. The preparation method comprises the following steps: step 1, dissolving a precursor; 2, adding a reagent; step 3, illumination hydrolysis; step 4, slowly drying; step 5, crystal growth; step 6, post-processing; an organic precursor containing C and Si elements is adopted as a raw material for preparing SiC powder particles, sufficient hydrolysis of the precursor is ensured by utilizing the oxidation-reduction characteristic generated by illumination, and the size and shape of SiC grains are controlled and the porosity is increased by adding a template agent, so that the specific surface area of the SiC powder particles is increased, and the specific surface area of the SiC powder particles is increased. And the growth speed and size of the crystal grains are reduced by adding the crystal grain growth inhibitor, and the surface energy of the crystal grains is changed by adding the surfactant, so that the surfactant and the template agent generate a synergistic effect, and the growth of the crystal grains is better controlled to obtain the SiC powder particles with high specific surface area.

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to a method for preparing SiC powder particles with high specific surface area and visible light response. Background Art

[0002] Silicon carbide is one of the typical representatives of the third generation of semiconductors. It has excellent properties such as stable chemical properties, high thermal conductivity, high electron mobility, high mechanical strength, high hardness, low price, and environmental friendliness. It has been widely used in industry in recent years. As an excellent semiconductor material, it is also widely used in photoinduced reaction systems, such as photoelectrocatalytic electrode materials, photocatalytic decomposition of water to produce hydrogen, etc. As a photocatalyst with industrial application prospects in the future, the existing silicon carbide semiconductor has the problem of too low specific surface area. It is generally believed that the specific surface area of ​​a catalyst with excellent catalytic performance should reach 100m 2 / g or more, while the specific surface area of ​​existing silicon carbide powder is only 6m 2 / g, which seriously restricts its catalytic performance when used as a catalyst. Therefore, effectively increasing the specific surface area of ​​silicon carbide powder is a key technical problem to be solved as an excellent photocatalyst.

[0003] In the existing silicon carbide production technology, the specific surface area of ​​silicon carbide powder is too low due to the following factors: 1. The existing technology cannot accurately control the growth of grains, and the excessive growth of grains may easily lead to an increase in the size of silicon carbide particles, thereby reducing the specific surface area; 2. The silicon carbide grains produced by the existing technology are relatively regular in shape, such as spherical or nearly spherical. This regular shape makes the specific surface area of ​​the particles relatively small; 3. The silicon carbide powder produced by the existing technology does not have a high porosity, resulting in a small specific surface area. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing SiC powder particles with a high specific surface area and visible light response, so as to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing SiC powder particles with a high specific surface area that responds to visible light, comprising the following steps: step 1, dissolving a precursor; step 2, adding a reagent; step 3, photo-hydrolysis; step 4, slow drying; step 5, crystal growth; step 6, post-treatment;

[0006] In the above step 1, an organic precursor containing C and Si elements is dissolved in a corresponding organic solvent, and a grain growth inhibitor is added and stirred until completely dissolved to obtain a solution A;

[0007] In the above step 2, the solution A obtained in step 1 is allowed to stand for 3 h to 5 h, and then a template and a surfactant are added, and the mixture is stirred and mixed to obtain a mixture B;

[0008] In the above step 3, the mixture B obtained in step 2 is hydrolyzed under light conditions to obtain a solution C;

[0009] In the above step 4, the solution C obtained in step 3 is dried to obtain a mixture D;

[0010] In the above step 5, the mixture D obtained in step 4 is calcined to obtain a mixture E;

[0011] In the above step six, the mixture E obtained in step five is washed and dried to obtain SiC powder particles with a high specific surface area.

[0012] Preferably, in step 1, the organic precursor is polycarbosilane, the organic solvent is tetrahydrofuran, and the usage ratio of polycarbosilane to tetrahydrofuran is 1:6-10.

[0013] Preferably, in step 1, the grain growth inhibitor is vanadium oxide, and the added amount is 1%-2% of the amount of the organic precursor.

[0014] Preferably, in step 2, the template is SBA-15, and the amount of SBA-15 added is 20% of the amount of the organic precursor.

[0015] Preferably, in step 2, the surfactant is sodium dodecylbenzene sulfonate, and the amount of sodium dodecylbenzene sulfonate added is 5% of the amount of the organic precursor.

[0016] Preferably, in step 3, the illumination wavelength is 190nm-1000nm, and the illumination intensity is 10mW / cm 2 -1000mW / cm 2 The hydrolysis time is 3-6h, the stirring speed is 100-200rpm, and stirring must be maintained throughout the hydrolysis process.

[0017] Preferably, in step 4, the drying treatment is specifically performed by slowly heating the temperature from room temperature to 80°C at a heating rate of 2°C / min, and then maintaining the temperature at 80°C for 2h.

[0018] Preferably, in step five, the calcination treatment is specifically as follows: the calcination temperature is 1300° C.-1500° C., the calcination time is 2 h, and the atmosphere is argon atmosphere.

[0019] Preferably, in step six, washing specifically comprises: washing the product several times with hydrofluoric acid until pH=7, the concentration of hydrofluoric acid is 10%, ultrasonic assisted washing is used during the washing process, the power is 500W, and each washing time is 10min-20min.

[0020] Preferably, in step six, the drying method is vacuum drying.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention adopts an organic precursor containing C and Si elements as a raw material for preparing SiC powder particles, utilizes the redox characteristics generated by light irradiation, ensures that the precursor is fully hydrolyzed, controls the size and shape of SiC grains by adding a template, increases the porosity, thereby increasing the specific surface area of ​​the SiC powder particles, reduces the growth rate and size of the grains by adding a grain growth inhibitor, and changes the surface energy of the grains by adding a surfactant, thereby producing a synergistic effect with the template, better controlling the growth of the grains, and obtaining SiC powder particles with a high specific surface area. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a flow chart of the method. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Please refer to the attached Figure 1 , an embodiment provided by the present invention: a method for preparing SiC powder particles with high specific surface area and visible light response, comprising the following steps: step 1, dissolving a precursor; step 2, adding a reagent; step 3, photo-hydrolysis; step 4, slow drying; step 5, crystal growth; step 6, post-processing;

[0025] In the above step 1, an organic precursor containing C and Si elements is dissolved in a corresponding organic solvent, and a grain growth inhibitor is added and stirred until completely dissolved to obtain a solution A; wherein the organic precursor is polycarbosilane, the organic solvent is tetrahydrofuran, and the ratio of polycarbosilane to tetrahydrofuran is 1:6-10; the grain growth inhibitor is vanadium oxide, and the addition amount is 1%-2% of the mass of the organic precursor;

[0026] In the above step 2, the solution A obtained in step 1 is allowed to stand for 3h-5h, and then a template and a surfactant are added, stirred and mixed to obtain a mixture B; wherein the template is SBA-15, and the amount of SBA-15 added is 20% of the weight of the organic precursor; the surfactant is sodium dodecylbenzene sulfonate, and the amount of sodium dodecylbenzene sulfonate added is 5% of the weight of the organic precursor;

[0027] In the above step 3, the mixture B obtained in step 2 is hydrolyzed under light conditions to obtain a solution C; wherein the light band is 190nm-1000nm, and the light intensity is 10mW / cm 2 -1000mW / cm 2 , the hydrolysis time is 3-6h, the stirring speed is 100-200rpm, and stirring must be maintained throughout the hydrolysis process;

[0028] In the above step 4, the solution C obtained in step 3 is dried, specifically: slowly heating the temperature from room temperature to 80°C at a heating rate of 2°C / min, and then maintaining the temperature at 80°C for 2h to obtain a mixture D;

[0029] In the above step 5, the mixture D obtained in step 4 is calcined, specifically: the calcination temperature is 1300° C.-1500° C., the calcination time is 2 h, and the atmosphere is argon atmosphere, to obtain a mixture E;

[0030] In the above step six, the mixture E obtained in step five is washed and dried to obtain SiC powder particles with a high specific surface area; wherein the washing is specifically: washing the product with hydrofluoric acid for several times until the pH is 7, the concentration of hydrofluoric acid is 10%, ultrasonic assisted washing is used during the washing process, the power is 500W, and the washing time for each time is 10min-20min; the drying method is vacuum drying.

[0031] Based on the above, the advantages of the present invention are that, when used, the organic precursor containing C and Si elements is used as the raw material for preparing SiC powder particles, and the redox characteristics generated by light are used to ensure that the precursor is fully hydrolyzed. By adding a template, the size and shape of the SiC grains are controlled to prevent excessive growth of the grains, so that the SiC grains have an irregular shape, and at the same time, the mesoporous structure of the template can be replicated to increase the porosity, thereby increasing the specific surface area of ​​the SiC powder particles; the present invention reduces the growth rate and size of the grains by adding a grain growth inhibitor, and changes the surface energy of the grains by adding a surfactant, affecting the growth direction and shape of the grains, and synergizing with the template to better control the grain growth; the specific surface area of ​​the SiC powder particles prepared by the present invention can reach 800m 2 / g, which is about 200 times that of the current commercial SiC powder particles.

[0032] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for preparing SiC powder particles with high specific surface area and visible light response, comprising the following steps: Step 1, dissolving the precursor; Step 2, adding the reagent; Step 3, photo-hydrolysis; Step 4, slow drying; Step 5, crystal growth; Step 6, post-processing; It is characterized by: In the above step 1, an organic precursor containing C and Si elements is dissolved in a corresponding organic solvent, and a grain growth inhibitor is added and stirred until completely dissolved to obtain a solution A; In the above step 2, the solution A obtained in step 1 is allowed to stand for 3 h to 5 h, and then a template and a surfactant are added, and the mixture is stirred and mixed to obtain a mixture B; In the above step 3, the mixture B obtained in step 2 is hydrolyzed under light conditions to obtain a solution C; In the above step 4, the solution C obtained in step 3 is dried to obtain a mixture D; In the above step 5, the mixture D obtained in step 4 is calcined to obtain a mixture E; In the above step six, the mixture E obtained in step five is washed and dried to obtain SiC powder particles with a high specific surface area.

2. The method for preparing SiC powder particles with high specific surface area and visible light response according to claim 1, characterized in that: In the step 1, the organic precursor is polycarbosilane, the organic solvent is tetrahydrofuran, and the usage ratio of polycarbosilane to tetrahydrofuran is 1:6-10.

3. The method for preparing SiC powder particles with high specific surface area and visible light response according to claim 1, characterized in that: In the step 1, the grain growth inhibitor is vanadium oxide, and the added amount is 1%-2% of the amount of the organic precursor.

4. The method for preparing SiC powder particles with high specific surface area and visible light response according to claim 1, characterized in that: In the step 2, the template is SBA-15, and the amount of SBA-15 added is 20% of the amount of the organic precursor.

5. The method for preparing SiC powder particles with high specific surface area and visible light response according to claim 1, characterized in that: In the step 2, the surfactant is sodium dodecylbenzene sulfonate, and the amount of sodium dodecylbenzene sulfonate added is 5% of the amount of the organic precursor.

6. The method for preparing SiC powder particles with high specific surface area and visible light response according to claim 1, characterized in that: In step 3, the illumination wavelength is 190nm-1000nm, and the illumination intensity is 10mW / cm 2 -1000mW / cm 2 The hydrolysis time is 3-6h, the stirring speed is 100-200rpm, and stirring must be maintained throughout the hydrolysis process.

7. The method for preparing SiC powder particles with high specific surface area and visible light response according to claim 1, characterized in that: In the step 4, the drying treatment is specifically as follows: slowly heating the temperature from room temperature to 80°C at a heating rate of 2°C / min, and then maintaining the temperature at 80°C for 2h.

8. The method for preparing SiC powder particles with high specific surface area and visible light response according to claim 1, characterized in that: In the step 5, the calcination treatment is specifically as follows: the calcination temperature is 1300° C.-1500° C., the calcination time is 2 hours, and the atmosphere is argon atmosphere.

9. The method for preparing SiC powder particles with high specific surface area and visible light response according to claim 1, characterized in that: In step six, washing specifically includes: washing the product with hydrofluoric acid for several times until pH=7, the concentration of hydrofluoric acid is 10%, ultrasonic assisted washing is used during the washing process, the power is 500W, and each washing time is 10min-20min.

10. The method for preparing SiC powder particles with high specific surface area and visible light response according to claim 1, characterized in that: In step six, the drying method is vacuum drying.

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