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CN-121972653-A - NiCo-MOF derived carbon nanotube wave-absorbing material with core-shell structure and preparation method thereof

CN121972653ACN 121972653 ACN121972653 ACN 121972653ACN-121972653-A

Abstract

The invention discloses a NiCo-MOF derived carbon nanotube wave-absorbing material with a core-shell structure and a preparation method thereof, and relates to the technical field of wave-absorbing materials. According to the method, a NiCo-MOF with a core-shell structure is obtained by controlling the proportion of solvents, then carbon nanotubes are grown on the surface of the NiCo-MOF in situ, the prepared MOF-derived carbon nanotubes have a hollow core-shell structure, and a layer of dense carbon nanotubes is covered on the surface of the MOF-derived carbon nanotubes. By adopting the structure, the conductivity of the material is greatly improved, the type of interface polarization is enriched, the excellent wave absorbing performance is shown in the frequency band of 2-18 GHz, the hollow structure is favorable for the internal multiple reflection of electromagnetic waves, when the matching thickness is 2.5 mm, the effective absorption bandwidth can reach 5.7 GHz, and the minimum absorption peak reaches 4.8GHz. The invention has simple process flow and lower cost, is suitable for large-scale preparation, and has wide application prospect in the fields of light broadband wave absorption, heat protection and the like.

Inventors

  • JIANG CHAO
  • Ding Zizhao
  • ZHAO ZIXIANG
  • LI YILE

Assignees

  • 中南大学

Dates

Publication Date
20260505
Application Date
20260203

Claims (9)

  1. 1. The preparation method of the NiCo-MOF derived carbon nanotube wave-absorbing material with the core-shell structure is characterized by comprising the following steps of: (1) Dissolving PVP in a mixed solution of deionized water and DMF, then adding benzene tricarboxylic acid, adding nickel nitrate hexahydrate and cobalt nitrate hexahydrate after the benzene tricarboxylic acid is dissolved to obtain a mixed solution, washing and drying powder obtained after hydrothermal treatment of the mixed solution; (2) And (3) placing the powder obtained in the step (1) in the middle of a tube furnace, performing staged dynamic atmosphere regulation and control in a heating stage, a reaction stage and a cooling stage, and opening a tube furnace cover after the tube furnace is naturally cooled to room temperature to obtain the NiCo-MOF derived carbon nanotube wave-absorbing material with a core-shell structure.
  2. 2. The preparation method of the NiCo-MOF derivative carbon nanotube wave-absorbing material with the core-shell structure, which is characterized in that in the mixed solution in the step (1), PVP has the concentration of 50-100g/mL, trimellitic acid has the concentration of 5-10mg/mL, and hexacobalt nitrate has the concentration of 10-50mg/mL, and hexanickel nitrate has the concentration of 10-20mg/mL; in the mixed solution in the step (1), the volume ratio of DMF and deionized water is 6:1-1:1.
  3. 3. The method for preparing the NiCo-MOF-derived carbon nanotube wave-absorbing material with the core-shell structure according to claim 1, wherein the mass ratio of the nickel hexanitrate to the cobalt hexanitrate in the step (1) is 1-5:1.
  4. 4. The method for preparing the NiCo-MOF-derived carbon nanotube wave-absorbing material with the core-shell structure according to claim 1, wherein in the step (1), the mixed solution is placed in a hydrothermal reaction kettle with a polytetrafluoroethylene lining for hydrothermal reaction, the hydrothermal reaction temperature is 120-180 ℃, and the time is 3-24 hours; Washing the powder with deionized water for several times, and washing with absolute ethanol for 4-24 hr at 30-90deg.C.
  5. 5. The method for preparing the NiCo-MOF-derived carbon nanotube wave-absorbing material with the core-shell structure, which is disclosed in claim 1, is characterized in that in the step (2), the heating stage speed is 5-15 ℃ per minute, the reaction stage temperature is 550-1000 ℃, the reaction stage time is 5-60min, and the cooling stage is natural cooling.
  6. 6. The method for preparing the NiCo-MOF-derived carbon nanotube wave-absorbing material with the core-shell structure according to claim 1, wherein in the step (2), the dynamic atmosphere comprises protective gas, reducing gas and carbon source gas, and the volume flow rates of the protective gas, the reducing gas and the carbon source gas are 400-500mL/min, 60-100mL/min and 5-40mL/min respectively; the protective gas is one or more of nitrogen or argon, the reducing gas is one or more of hydrogen or nitric oxide, and the carbon source gas is one or more of acetylene or methane.
  7. 7. The method for preparing the NiCo-MOF-derived carbon nanotube wave-absorbing material with the core-shell structure according to claim 1, wherein in the step (2), the staged dynamic atmosphere control comprises the following steps: (2-1) introducing protective gas in the initial heating stage, and introducing reducing gas when the temperature is raised to 200-400 ℃; (2-2) after the temperature is raised to the reaction temperature of the reaction stage, stabilizing for 5-20 min, and introducing carbon source gas; (2-3) after the carbon source gas is introduced for 5-60min, closing the carbon source gas channel, closing the injection pump, closing the temperature control program of the tube furnace, and starting natural cooling of the tube furnace; (2-4) closing the reducing gas channel when the tube furnace is cooled to 500 ℃; (2-5) closing the protective gas passage when the tube furnace is cooled to 100 ℃.
  8. 8. A NiCo-MOF-derived carbon nanotube wave-absorbing material having a core-shell structure, characterized in that it is prepared by the preparation method of any one of claims 1 to 7.
  9. 9. The NiCo-MOF-derived carbon nanotube absorbing material with a core-shell structure according to claim 8, wherein the NiCo-MOF-derived carbon nanotube absorbing material uses carbon as a shell, nickel cobalt as a core, and carbon nanotubes are grown on the surface in situ.

Description

NiCo-MOF derived carbon nanotube wave-absorbing material with core-shell structure and preparation method thereof Technical Field The invention relates to the technical field of wave-absorbing materials, in particular to a NiCo-MOF derived carbon nano tube wave-absorbing material with a core-shell structure and a preparation method thereof. Background Along with the rapid development of modern electronic technology and wireless communication, the application of electromagnetic waves in civil, industrial and national defense fields is deepened, the problems of electromagnetic interference and information leakage are increasingly severe, and higher requirements are put on high-performance electromagnetic wave absorbing materials. The ideal wave absorbing material needs to realize strong absorption in a wide frequency band, and has the characteristics of thin thickness, light weight, environmental resistance, good stability and the like, so as to meet the severe requirements of fields such as a fifth-generation communication system, a high-frequency radar, a stealth technology, a flexible electronic device and the like on the material performance. Among the various wave-absorbing materials, carbon-based materials are of great interest because of their low density, tunable dielectric properties and good chemical stability. Particularly, the carbon nano tube not only has high conductivity and large length-diameter ratio, but also has obvious dielectric loss capacity, and is beneficial to the conversion and dissipation of electromagnetic energy. However, the single carbon nanotube has the problems of easy agglomeration, poor impedance matching, weak magnetism and the like, and limits the absorption performance and practical application of the single carbon nanotube in a low frequency band. Metal organic framework Materials (MOFs) have been widely studied in recent years because of their porosity, high specific surface area and diversity of metal centers, from which structurally controllable carbon/metal composite wave-absorbing materials can be derived after pyrolysis. At present, although research has focused on the application of MOF-derived carbon materials in the wave-absorbing field, there is still a lack of systematic and intensive research about specific compounding strategies and fine controllable preparation thereof, and limited exploration is made on the directional compounding modes of MOFs and other functional components on a molecular or nano scale. In addition, for the absorption requirements of different frequency bands, more experiments and mechanism researches are needed to support how to design and prepare MOF derivative composite materials with specific component gradients, core-shell structures or multistage pore channels. Therefore, understanding the structure-activity relationship of the MOF derived carbon-based wave-absorbing material is deepened, and development of a composite and preparation method with guidance is a key for improving the low-frequency absorption performance of the material and promoting the practical application of the material. Disclosure of Invention The invention aims to provide a NiCo-MOF derived carbon nanotube wave-absorbing material with a core-shell structure and a preparation method thereof, which solve the problems. The preparation process flow is simple, the cost is low, and the prepared material has excellent wave absorbing performance. Based on the above object, the invention provides a preparation method of a NiCo-MOF derived carbon nanotube wave-absorbing material with a core-shell structure, which comprises the following steps: (1) Dissolving PVP in a mixed solution of deionized water and DMF, then adding benzene tricarboxylic acid, adding nickel nitrate hexahydrate and cobalt nitrate hexahydrate after the benzene tricarboxylic acid is dissolved to obtain a mixed solution, washing and drying powder obtained after hydrothermal treatment of the mixed solution; (2) And (3) placing the powder obtained in the step (1) in the middle of a tube furnace, performing staged dynamic atmosphere regulation and control in a heating stage, a reaction stage and a cooling stage, and opening a tube furnace cover after the tube furnace is naturally cooled to room temperature to obtain the NiCo-MOF derived carbon nanotube wave-absorbing material with a core-shell structure. Preferably, in the mixed solution in the step (1), PVP is 50-100g/mL, trimellitic acid is 5-10mg/mL, cobalt hexanitrate is 10-50mg/mL, nickel hexanitrate is 10-20mg/mL, and the ratio is 1-5:1. In the mixed solution in the step (1), the volume ratio of DMF and deionized water is 6:1-1:1. Preferably, the concentration of cobalt hexanitrate is 10-20mg/mL. Preferably, in the step (1), the mixed solution is placed in a hydrothermal reaction kettle with a polytetrafluoroethylene lining to transfer the precursor solution to perform hydrothermal reaction, wherein the hydrothermal reaction temperature is 120-180 ℃