VSe2-coated CoFe2O4 composite wave-absorbing material and preparation method thereof

Abstract

The invention discloses a VSe2atCoFe2O4 composite wave-absorbing material and a preparation method thereof.The preparation method comprises the following steps that 1, cobalt chloride and ferric chloride are dissolved in deionized water, the PH is adjusted through a sodium hydroxide solution to be 12-13, then the solution is transferred into a high-pressure kettle, hydrothermal treatment is conducted for 20-24 h, after the reaction is finished, washing is conducted for multiple times through deionized water and ethyl alcohol, drying is conducted, and CoFe2O4 is obtained; (2) ammonium metavanadate and oxalic acid are dissolved in deionized water, selenium powder is added after dissolution, a certain amount of cobalt ferrite is added after uniform stirring, stirring and ultrasonic treatment are carried out for 1-2 h respectively, then the mixture is transferred into a high-pressure kettle, hydrothermal treatment is carried out for 20-24 h, centrifugation is carried out after the reaction is finished, washing is carried out multiple times with deionized water and ethyl alcohol, drying is carried out, and a series of VSe2CoFe2O4 composite wave-absorbing materials with different cobalt ferrite contents are obtained. The preparation method adopts a two-step hydrothermal method, the method is simple, the cost is lower, the experimental period is shorter, the reaction condition is mild, non-toxic raw materials are adopted, and the preparation process meets the industrial production of environment-friendly requirements.

Description

Technical Field

[0001] The invention relates to wave absorbing material technology, and in particular to a VSe2@CoFe2O4 wave absorbing material and a preparation method thereof. Background Art

[0002] With the rapid development of wireless electronic technology, wireless electronic technology and artificial intelligence have brought convenience and intelligent life to human beings. However, electromagnetic pollution caused by electromagnetic waves generated by electronic devices also seriously endangers human health. Microwave absorbing materials can absorb incident electromagnetic waves and convert them into heat energy to consume or destroy electromagnetic interference. A key issue in reducing and controlling electromagnetic wave pollution is the development of microwave absorbing materials.

[0003] Among the absorbing materials, ferrite has many good applications in military and civilian fields due to its high saturation magnetization, peroxide resistance and corrosion resistance. However, due to the limitation of the "Snoek" limit, its magnetic loss in the high frequency region is very small and it cannot effectively absorb electromagnetic waves. CoFe2O4, as a typical spinel ferrite, has appropriate saturation magnetization, strong anisotropy and high chemical stability, and is often used as an electromagnetic wave absorber. However, since pure CoFe2O4 has high density and poor matching impedance in real applications, it is often compounded with dielectric materials, which increases the loss capacity while increasing the impedance matching, which can significantly reduce the reflection loss of the material.

[0004] Transition metal dichalcogenides (TMDs) have become one of the microwave absorbing materials with great application potential due to their high specific surface area, unique electronic structure and rich design methods. The current research mainstream is developing Mo-based and W-based dichalcogenides, such as MoS2, WS2, MoSe2 and WSe2, while vanadium-based materials are rarely developed. As a typical TMDs, VSe2 is different from other TMDs materials in that it not only has excellent properties of large specific surface area and unique electronic structure, but also exhibits intrinsic metallic conductivity, which can enhance its electrical loss capacity. Summary of the invention

[0005] The object of the present invention is to provide a VSe2@CoFe2O4 absorbing material with simple preparation process, low cost and absorbing performance and a preparation method thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing a VSe2@CoFe2O4 absorbing material comprises the following steps: (1) Dissolve cobalt chloride and ferric chloride in a deionized water solution in a molar ratio of 1:(2-3); (2) Using sodium hydroxide solution, adjust the pH of the solution obtained in step 1 to 12-13, and continue stirring for 20-60 min; (3) The mixed solution was transferred to an autoclave with a polytetrafluoroethylene liner, and the mixture was reacted at 180-200 °C for 20-24 h. After the reaction was completed, the mixture was cooled to room temperature, washed with deionized water and ethanol, and dried to obtain CoFe2O4. (4) Dissolve ammonium metavanadate and oxalic acid in deionized water at a molar ratio of 1:(9-10), stir to fully dissolve, add selenium powder, stir for 30-60 min to make it fully uniform, then add a certain amount (0.1-0.3 mmol) of CoFe2O4 to the mixed solution, stir and ultrasonicate for 1-2 h each to make it fully mixed; (5) The mixed solution was transferred to an autoclave with a polytetrafluoroethylene liner and reacted in a sealed state at 180-200 °C for 20-24 h. After the reaction was completed, it was cooled to room temperature, washed thoroughly with ethanol, and dried to obtain a VSe2@CoFe2O4 composite absorbing material.

[0007] The method for preparing the VSe2@CoFe2O4 absorbing material according to claim 1, characterized in that the concentration of the sodium hydroxide solution prepared in step (2) is 0.8~1 mol / L.

[0008] The method for preparing the VSe2@CoFe2O4 absorbing material according to claim 1 is characterized in that the hydrothermal temperature in steps (3) and (5) is 180-200°C and the hydrothermal time is 20-24 h.

[0009] The method for preparing the VSe2@CoFe2O4 absorbing material according to claim 1, characterized in that the amount of CoFe2O4 added in step (4) is 0.1-0.3 mmol.

[0010] A VSe2@CoFe2O4 absorbing material prepared by the method according to any one of claims 1 to 5, characterized in that the microstructure of the VSe2@CoFe2O4 absorbing material is a composite structure in which nano-cobalt ferrite particles are attached to the gaps between VSe2 nanosheets. Compared with the prior art, the present invention has the following technical effects: 1. Constructing multiple heterogeneous interfaces using materials with multiple complementary or enhanced properties is the key to solving the problem of electromagnetic wave absorption. This application uses cobalt ferrite and flaky VSe2 with a unique structure to construct multiple heterogeneous interfaces, which can produce a large amount of interface polarization; VSe2 and CoFe2O4 adjust the impedance matching of the composite material; there are a large number of crystal defects in the VSe2 nanosheets, and these V and Se vacancies will produce dipoles under the action of the electric field, which will lead to dipole polarization; the conductive VSe2 nanosheets are cross-linked with each other, which can effectively enhance the conduction loss of the material.

[0011] 2. In the present application, the cobalt ferrite prepared by the hydrothermal method has the morphology of nanoparticles, and the prepared VSe2 has the morphology of flake self-forming flower balls. The cobalt ferrite particles in the composite material are evenly attached to the flake VSe2, which can effectively promote multiple reflections and scattering of electromagnetic waves between the composite materials, and synergistically utilize the dielectric loss of VSe2 and the magnetic loss of cobalt ferrite to effectively lose electromagnetic waves. Therefore, the VSe2@CoFe2O4 absorbing material prepared by the present invention can effectively eliminate the incident electromagnetic waves.

[0012] 3. The preparation of the present invention adopts a two-step hydrothermal method, which is simple, low in cost, short in experimental cycle, mild in reaction conditions, does not require the use of any surfactant in the synthesis process, does not introduce any organic pollutants, and does not generate any organic waste liquid in the entire experimental process. It uses non-toxic raw materials, and the raw materials and preparation process meet the requirements of industrial production in terms of environmental protection, laying a good foundation for applied research and having good application prospects in the field of wave absorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a SEM image of the VSe2@CoFe2O4 absorbing material of Example 1 of the present invention; Figure 2 This is the SEM image of the VSe2@CoFe2O4 absorbing material of Example 2 of the present invention: Figure 3 This is the SEM image of the VSe2@CoFe2O4 absorbing material of Example 3 of the present invention. Implementation

[0014] The specific contents of the present invention are further explained in detail below in conjunction with the implementation method.

[0015] This embodiment provides a method for preparing a VSe2@CoFe2O4 absorbing material, comprising the following steps: (1) Dissolve cobalt chloride and ferric chloride in a deionized water solution in a molar ratio of 1:(2-3); (2) Using sodium hydroxide solution, adjust the pH of the solution obtained in step 1 to 12-13, and continue stirring for 20-60 min; (3) The mixed solution was transferred to an autoclave with a polytetrafluoroethylene liner, and the mixture was reacted at 180-200 °C for 20-24 h. After the reaction was completed, the mixture was cooled to room temperature, washed with deionized water and ethanol, and dried to obtain CoFe2O4. (4) Dissolve ammonium metavanadate and oxalic acid in deionized water at a molar ratio of 1:(9-10), stir to fully dissolve, add selenium powder, stir for 30-60 min to make it fully uniform, then add a certain amount (0.1-0.3 mmol) of CoFe2O4 to the mixed solution, stir and ultrasonicate for 1-2 h each to make it fully mixed; (5) The mixed solution was transferred to an autoclave with a polytetrafluoroethylene liner and reacted in a sealed state at 180-200 °C for 20-24 h. After the reaction was completed, it was cooled to room temperature, washed thoroughly with ethanol, and dried to obtain a VSe2@CoFe2O4 composite absorbing material.

[0016] To further illustrate the technical solution of the present invention in detail, it is described in detail below in conjunction with specific embodiments. Example 1

[0017] This embodiment provides a method for preparing a VSe2@CoFe2O4 absorbing material, comprising the following steps: (1) Dissolve cobalt chloride and ferric chloride in 50 ml of deionized water in a molar ratio of 1:2. (2) Add 12 ml of the prepared 1 mol / L sodium hydroxide solution, adjust the pH to 13, and stir for 30 min. (3) The mixed solution was transferred to an autoclave with a polytetrafluoroethylene liner, and the mixture was reacted at 200 °C for 20 h. After the reaction was completed, the mixture was cooled to room temperature, washed with deionized water and ethanol, and dried to obtain CoFe2O4. (4) Dissolve ammonium metavanadate, oxalic acid and selenium powder in 60 ml of deionized water in a molar ratio of 1:9:3, stir to make them fully uniform, then add a certain amount of prepared CoFe2O4 in a molar ratio of ammonium metavanadate to cobalt ferrite of 2:0.1 into the mixed solution, stir and sonicate for 1 h each to make them fully mixed; (5) The mixed solution was transferred to an autoclave with a polytetrafluoroethylene liner and reacted in a sealed state at 200 °C for 20 h. After the reaction was completed, it was cooled to room temperature, washed thoroughly with ethanol, and dried to obtain a VSe2@CoFe2O4 composite absorbing material. Example 2

[0018] This embodiment provides a method for preparing a VSe2@CoFe2O4 absorbing material, comprising the following steps: (1) Dissolve cobalt chloride and ferric chloride in 50 ml of deionized water in a molar ratio of 1:2. (2) Add 12 ml of 0.8 mol / L sodium hydroxide solution, adjust the pH to 12, and stir for 30 min. (3) The mixed solution was transferred to an autoclave with a polytetrafluoroethylene liner, and the mixture was reacted at 190°C for 22 hours. After the reaction was completed, the mixture was cooled to room temperature, washed with deionized water and ethanol, and dried to obtain CoFe2O4. (4) Dissolve ammonium metavanadate, oxalic acid and selenium powder in 60 ml of deionized water in a molar ratio of 1:10:3, stir to make them fully uniform, then add a certain amount of prepared CoFe2O4 in a molar ratio of ammonium metavanadate to cobalt ferrite of 2:0.2 to the mixed solution, stir and sonicate for 1 h each to make them fully mixed; (5) The mixed solution was transferred to an autoclave with a polytetrafluoroethylene liner and reacted in a sealed state at 190 °C for 22 h. After the reaction was completed, it was cooled to room temperature, washed thoroughly with ethanol, and dried to obtain a VSe2@CoFe2O4 composite absorbing material. Example 3

[0019] This embodiment provides a method for preparing a VSe2@CoFe2O4 absorbing material, comprising the following steps: (1) Dissolve cobalt chloride and ferric chloride in 50 ml of deionized water in a molar ratio of 1:3. (2) Add 12 ml of the prepared 0.8 mol / L sodium hydroxide solution, adjust the pH to 12, and stir for 30 min. (3) The mixed solution was transferred to an autoclave with a polytetrafluoroethylene liner, and the mixture was reacted at 180 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature, washed with deionized water and ethanol, and dried to obtain CoFe2O4. (4) Dissolve ammonium metavanadate, oxalic acid and selenium powder in 60 ml of deionized water in a molar ratio of 1:9:3, stir to make them fully uniform, then add a certain amount of prepared CoFe2O4 in a molar ratio of ammonium metavanadate to cobalt ferrite of 2:0.3 to the mixed solution, stir and sonicate for 1 h each to make them fully mixed; (5) The mixed solution was transferred to an autoclave with a polytetrafluoroethylene liner and reacted in a sealed state at 180 °C for 24 h. After the reaction was completed, it was cooled to room temperature, washed thoroughly with ethanol, and dried to obtain a VSe2@CoFe2O4 composite absorbing material.

[0020] Figure 1 , Figure 2 , Figure 3 The following are SEM images of the VSe2@CoFe2O4 absorbing materials prepared in Examples 1 to 3. Figure 1 and Figure 2 It can be seen that the prepared VSe2@CoFe2O4 composite material presents a composite structure in which nano-CoFe2O4 particles are attached to the flower balls composed of flaky VSe2, and as the CoFe2O4 content increases, more CoFe2O4 is embedded in the gaps of the flaky VSe2, but it still shows a composite structure in which CoFe2O4 particles are embedded in the gaps of the microspheres composed of flaky VSe2. Figure 3 As shown, when the CoFe2O4 content reaches a certain level, CoFe2O4 self-aggregates into spheres instead of being uniformly embedded in the gaps between microspheres composed of flaky VSe2. The number of CoFe2O4 particles embedded in the gaps between VSe2 is greatly reduced, and the composite structure is destroyed.

Claims

1. A method for preparing a VSe2@CoFe2O4 absorbing material, characterized in that: The steps include: (1) Dissolve cobalt chloride and ferric chloride in a deionized water solution in a molar ratio of 1:(2-3); (2) adjusting the pH of the solution obtained in step (1) to 12-13 using sodium hydroxide solution, and continuing stirring for 20-60 min; (3) The mixed solution was transferred to an autoclave with a polytetrafluoroethylene liner, and the mixture was reacted at 180-200 °C for 20-24 h. After the reaction was completed, the mixture was cooled to room temperature, washed with deionized water and ethanol, and dried to obtain CoFe2O4. (4) Dissolve ammonium metavanadate and oxalic acid in deionized water at a molar ratio of 1:(9-10), stir to fully dissolve, add selenium powder, stir for 30-60 min to make it fully uniform, then add a certain amount (0.1-0.3 mmol) of CoFe2O4 to the mixed solution, stir and ultrasonicate for 1-2 h each to make it fully mixed; (5) The mixed solution was transferred to an autoclave with a polytetrafluoroethylene liner and reacted in a sealed state at 180-200 °C for 20-24 h. After the reaction was completed, it was cooled to room temperature, washed thoroughly with ethanol, and dried to obtain a VSe2@CoFe2O4 composite absorbing material.

2. The method for preparing the VSe2@CoFe2O4 absorbing material according to claim 1, characterized in that: The concentration of the sodium hydroxide solution prepared in step (2) is 0.8-1 mol / L.

3. The method for preparing the VSe2@CoFe2O4 absorbing material according to claim 1, characterized in that: In the steps (3) and (5), the hydrothermal temperature is 180-200°C and the hydrothermal time is 20-24 h.

4. The method for preparing the VSe2@CoFe2O4 absorbing material according to claim 1, characterized in that: The amount of CoFe2O4 added in step (4) is 0.1-0.3 mmol.

5. A VSe2@CoFe2O4 absorbing material prepared by the method according to any one of claims 1 to 5, characterized in that: The microstructure of the VSe2@CoFe2O4 absorbing material is a composite structure in which nano-cobalt ferrite particles are attached to the gaps between VSe2 nanosheets.

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