CN-121976324-A - MWCNTs modified CeO2Co hollow nanofiber absorbent and preparation method thereof

Abstract

The invention relates to a CeO 2 /Co hollow nanofiber absorbent modified by MWCNTs and a preparation method thereof. The technical scheme includes that water, ethanol and ammonia water are mixed to obtain a solution A, orthosilicate and the solution A are mixed and stirred for solid-liquid separation to obtain SiO 2 microsphere template powder, metal salts containing Co 2+ ions and Ce 3+ ions are sequentially dissolved in N, N-dimethylformamide to obtain a solution B, siO 2 microsphere template powder is placed in the solution B to obtain suspension, polyvinylpyrrolidone powder is placed in the suspension and stirred to obtain precursor spinning solution, nanofiber precursors obtained through electrostatic spinning are mixed with dicyandiamide powder for carbothermic reduction reaction, and then the obtained carbonized treatment product is placed in NaOH aqueous solution for stirring, solid-liquid separation and drying to obtain the MWCNTs modified CeO 2 /Co hollow nanofiber absorbent. The obtained product has strong loss capacity and stable hollow structure, and can realize decoupling regulation and control of loss capacity and impedance matching.

Inventors

• CHEN FU
• ZHOU RUNYANG
• LI XIANGCHENG
• CHEN PINGAN
• ZHU YINGLI
• WU JIANG
• Qiao Mengke
• Luo Gangtao

Assignees

• 武汉科技大学

Dates

Publication Date

20260505

Application Date

20260119

Claims (10)

1. 1. The preparation method of the MWCNTs modified CeO 2 /Co hollow nanofiber absorbent is characterized by comprising the following steps of: Step 1, mixing materials according to the volume ratio of water to ethanol to ammonia water of 1:3-6:0.3-0.5 to obtain a solution A, mixing materials according to the volume ratio of orthosilicate to the solution A of 1:10-15, stirring for 1-3 h, carrying out solid-liquid separation, washing and drying to obtain SiO 2 microsphere template powder; Step 2, dissolving a metal salt containing Co 2+ ions and a metal salt containing Ce 3+ ions in an N, N-dimethylformamide solution according to a solid-to-liquid ratio of 75-150 g/L, and stirring for 10-30 min to obtain a solution B; The mass of the metal salt containing Co 2+ ions is the same as that of the metal salt containing Ce 3+ ions; Step 3, placing the SiO 2 microsphere template powder into the solution B according to the solid-to-liquid ratio of 50-100 g/L, and mixing to obtain a suspension; Step 4, placing polyvinylpyrrolidone powder into the suspension according to a solid-to-liquid ratio of 20-40 g/L, and stirring for 1-4 hours at a temperature of 40-70 ℃ to obtain a precursor spinning solution; Step 5, mixing the nanofiber precursor and dicyandiamide powder according to the mass ratio of 0.5-2:1, heating to 700-900 ℃ at the speed of 2-5 ℃ per minute, and performing carbothermic reaction for 1-3 hours to obtain carbonized treatment substances; and 6, dissolving NaOH particles in water according to the solid-liquid ratio of 100-200 g/L, mixing to obtain a solution C, adding the carbonized product into the solution C according to the solid-liquid ratio of 20-40 g/L, mixing, stirring for 1-4 h, performing solid-liquid separation, washing and drying to obtain the MWCNTs modified CeO 2 /Co hollow nanofiber absorbent.
2. 2. The preparation method of the MWCNTs modified CeO 2 /Co hollow nanofiber absorbent according to claim 1, wherein the concentration of the ammonia water is 10-30wt%.
3. 3. The method for preparing the MWCNTs modified CeO 2 /Co hollow nanofiber absorbent according to claim 1, wherein the orthosilicate is one of methyl orthosilicate, ethyl orthosilicate and propyl orthosilicate.
4. 4. The method for preparing the MWCNTs modified CeO 2 /Co hollow nanofiber absorbent according to claim 1, wherein the metal salt containing Ce 3+ ions is one of cerium nitrate, cerium sulfate and cerium chloride.
5. 5. The method for preparing the MWCNTs modified CeO 2 /Co hollow nanofiber absorbent according to claim 1, wherein the metal salt containing Co 2+ ions is one of cobalt nitrate, cobalt sulfate and cobalt chloride.
6. 6. The preparation method of the MWCNTs modified CeO 2 /Co hollow nanofiber absorbent according to claim 1, wherein the voltage of the electrostatic spinning is 12-24 kV.
7. 7. The preparation method of the MWCNTs modified CeO 2 /Co hollow nanofiber absorbent according to claim 1, wherein the stirring rotation speed in the step 1 is 300-700 rpm, and the stirring rotation speeds in the step 2, the step 4 and the step 7 are the same as those in the step 1.
8. 8. The preparation method of the MWCNTs modified CeO 2 /Co hollow nanofiber absorbent according to claim 1, wherein the washing is carried out 2-4 times by deionized water, and the washing in the step 7 is the same as the washing in the step 1.
9. 9. The preparation method of the MWCNTs modified CeO 2 /Co hollow nanofiber absorbent according to claim 1, wherein the drying temperature in the step 1 is 50-80 ℃, the drying time is 6-12 h, and the drying in the step 7 is the same as that in the step 1.
10. 10. The MWCNTs modified CeO 2 /Co hollow nanofiber absorbent is characterized in that the MWCNTs modified CeO 2 /Co hollow nanofiber absorbent is prepared by the preparation method of the MWCNTs modified CeO 2 /Co hollow nanofiber absorbent according to any one of claims 1-9.

Description

MWCNTs modified CeO 2/Co hollow nanofiber absorbent and preparation method thereof Technical Field The invention belongs to the technical field of hollow nanofiber absorbents. In particular to a CeO 2/Co hollow nanofiber absorbent modified by MWCNTs and a preparation method thereof. Background As an important method for directly and continuously preparing one-dimensional nanofiber materials, the electrostatic spinning technology provides an ideal way for constructing fiber-based wave absorbers with large length-diameter ratio and adjustable components. By the technology, the multifunctional precursors can be uniformly filled in the fiber, and a foundation is laid for the subsequent complex microstructure and multicomponent design. The ideal wave absorbing material needs to have the characteristics of thin thickness, light weight, wide frequency band, strong absorption and the like, which prompt researchers to aim at introducing a multiple loss mechanism into the electrospun fiber to enhance the electromagnetic wave attenuation capability and optimize impedance matching through component or structural design. At present, the conductive layer is coated on the surface of the electrostatic spinning fiber by a physical adsorption method, so that the electromagnetic wave loss capacity can be improved. For example, the prior art discloses a strategy (Zhou X, Chuai D, Zhu D, et al, Electrospun Synthesis of Reduced Graphene Oxide(RGO)/NiZn Ferrite Nanocomposites for Excellent Microwave Absorption Properties, Journal of Superconductivity andNovel Magnetism.32(2019) 2687-2697), for coating Reduced Graphene Oxide (RGO) on the surface of Ni-Zn ferrite doped composite fiber by using a physical adsorption method, and the RGO/Ni 0.3Zn0.7Fe2O4 composite material prepared by the strategy has the minimum reflection loss when the coating thickness is 2.0mmThe effective absorption bandwidth is 3.68GHz at 37.71 dB. However, the coating layer obtained in the process has poor structural stability and weak bonding force with the fiber matrix, and cannot form a continuous and efficient conductive network, so that the improvement of the loss capacity of the wave absorber is limited. In addition, to optimize the impedance matching capability of the wave-absorbing material, it is an effective strategy to construct a porous structure inside the fiber. For example, the prior art discloses a method (Zuo X, Xu P, Zhang C, et al, Porous magnetic carbon nanofibers(P-CNF/Fe) for low-frequency electromagnetic wave absorption synthesized by electrospinning, Ceramics International.45(2019)4474-4481), for constructing a porous structure inside an electrospun fiber using polymethyl methacrylate (PMMA) as a pore former based on a thermal decomposition method, which can decompose components with poor thermal stability in a fiber precursor at high temperature carbonization, thereby forming a porous structure inside the electrospun fiber, and thus optimizing the impedance matching capability of the material. When the matching thickness of the prepared P-CNF/Fe composite material is 4.1mm, the minimum reflection loss of the P-CNF/Fe composite material is-44.86 dB, and the effective absorption bandwidth covers 3.28GHz. However, the porous structure obtained in the process is unstable, the degree of hollowness is not controllable, and effective regulation and control of impedance matching are difficult to realize. In addition, metal salt is doped into the electrostatic spinning precursor fiber by a blending method, and then the binary carbon/magnetic composite nanofiber is prepared by carbothermal reduction treatment. The method utilizes the magnetoelectric synergistic effect, and can adjust impedance matching while improving the loss capacity. For example, the prior art discloses a strategy (Lv J, Xiao Hui, Bin, et al, Structural and Carbonized Design of 1D FeNi/C Nanofibers with Conductive Network to Optimize Electromagnetic Parameters and Absorption Abilities, ACS Sustainable Chemistry&Engineering.6(2018) 7239-7249), for introducing FeNi metal particles into a carbon fiber matrix by blending, wherein the minimum reflection loss of the FeNi/C composite material prepared by the blending method reaches-24.8 dB at 9.4GHz, the thickness is 2.7mm, and the effective absorption bandwidth reaches 4.4GHz at 1.8mm thickness. However, although the multi-component design can regulate and control the impedance matching characteristic of the material to a certain extent, a coupling relation exists between the impedance matching characteristic and the loss capacity, and the impedance matching characteristic and the loss capacity are difficult to regulate and control independently, so that the wave-absorbing material is difficult to realize the efficient absorption effect. Therefore, the prior art has the defects of limited improvement of the loss capacity of the absorbent, unstable hollow structure, enhanced loss capacity, difficult decoupling regulation and control