A CNT@FeCoNi-MXene / MAX material, a preparation method thereof and application thereof as a wave-absorbing material

Abstract

The application relates to a CNT@FeCoNi-MXene / MAX material, a preparation method thereof and application thereof as a wave-absorbing material. The CNT@FeCoNi-MXene / MAX material is prepared by etching MXene doped with magnetic metal iron, cobalt and nickel composite carbon nanotubes through molten salt; the mass ratio of CNT:FeCoNi-MXene / MAX is 1:(0.5-2). Ti3AlC2, a magnetic metal molten salt and a fluxing agent are mixed, high-temperature etching is carried out, the etched material is mixed with carbon nanotubes, and the CNT@FeCoNi-MXene / MAX material is obtained. The CNT@FeCoNi-MXene / MAX material prepared by etching MXene doped with magnetic metal iron, cobalt and nickel composite carbon nanotubes through molten salt has excellent wave-absorbing performance. The wave-absorbing material can realize high-efficiency absorption with minimum reflection loss of-68.15 dB in a low-frequency C section, and can realize full-frequency coverage by adjusting the thickness.

Description

Technical Field

[0001] This invention belongs to the field of microwave absorbing material preparation and application technology, specifically relating to a CNT@FeCoNi-MXene / MAX material, its preparation method, and its application as a microwave absorbing material. Background Technology

[0002] The rapid development of 5G technology has significantly improved social productivity and people's quality of life. However, with the rapid iteration and upgrading of electronic devices, mobile communications, and wireless systems, the resulting electromagnetic pollution problem is becoming increasingly prominent. As a byproduct of modern technological development, electromagnetic interference and radiation not only threaten the security of information transmission but also pose a potential hazard to human health—high-intensity microwaves can directly cause abnormal operation or even permanent damage to electronic devices. Against this backdrop, electromagnetic wave absorbing materials, as a key technology for solving electromagnetic pollution, are directly related to breakthroughs in electromagnetic technology and the safe operation of precision equipment. This technology not only has significant value in the civilian field but also shows broad application prospects in strategic industries such as national defense, intelligent transportation, aerospace, and medical equipment. Although some two-dimensional (2D) carbon-based materials have strong electromagnetic wave (EMW) absorption and radar cross section (RCS) reduction capabilities in the mid-to-high frequency bands, the challenge of low-frequency absorption remains unresolved. MXene, as a prominent 2D nanomaterial with different types, has expanded the field of 2D semiconductors and conductors. Its excellent conductivity, large specific surface area, and significant polarizability make it an ideal candidate for electromagnetic wave absorption. Most research on MXene absorption focuses on the mid-to-high frequency bands, while there is a lack of exploration into induced electromagnetic coupling in the low frequency band. It is very reasonable to solve the low-frequency impedance mismatch by integrating magnetic materials (such as magnetic cobalt, nickel, ferrite, alloys and their composites). Therefore, low-frequency absorbing materials have always been a research hotspot in the field of absorbing materials. Summary of the Invention

[0003] To address the aforementioned technical problems, the purpose of this invention is to provide a CNT@FeCoNi-MXene / MAX material, its preparation method, and its application as a microwave absorbing material. The CNT@FeCoNi-MXene / MAX material provided by this invention utilizes the electromagnetic resonance absorption mechanism and the superior magnetic loss properties of magnetic materials. The synergistic effect of carbon nanotubes and magnetic metal elements enhances its microwave absorption performance in the C-band.

[0004] To achieve the above-mentioned objectives, the technical solution adopted by this invention is: a CNT@FeCoNi-MXene / MAX material, which is a CNT@FeCoNi-MXene / MAX material made by etching MXene-doped magnetic iron-cobalt-nickel composite carbon nanotubes with molten salt; by mass ratio, CNT:FeCoNi-MXene / MAX = 1:(0.5-2).

[0005] Furthermore, by mass ratio, CNT:FeCoNi-MXene / MAX = 1:1.

[0006] A method for preparing CNT@FeCoNi-MXene / MAX material includes the following steps:

[0007] (1) Take Ti3AlC2, iron salt, cobalt salt, nickel salt and flux, grind them into powder, mix them evenly, place them in a tube furnace, etch them at high temperature under nitrogen atmosphere, cool them naturally to room temperature, wash them with ultrapure water, filter them and dry them to obtain FeCoNi-MXene / MAX material;

[0008] (2) The FeCoNi-MXene / MAX material obtained in step (1) and carbon nanotubes (CNTs) are placed in an ethanol solution, ultrasonically stirred and mixed, washed with ultrapure water, filtered and dried to obtain CNT@FeCoNi-MXene / MAX material.

[0009] Furthermore, the iron salt is FeCl2·4H2O; the cobalt salt is CoCl2; the nickel salt is NiCl2; and the flux is NaCl and KCl.

[0010] Furthermore, in the molar ratio, Ti3AlC2:FeCl2·4H2O:CoCl2:NiCl2:NaCl:KCl=1:(3-10):(3-6):(3-6):2:2.

[0011] Furthermore, in molar ratio, Ti3AlC2:FeCl2·4H2O:CoCl2:NiCl2:NaCl:KCl=1:3:3:3:2:2.

[0012] Further, in step (1), the high-temperature etching is performed at 700 ℃ - 800 ℃. High-temperature etching at ℃ for 15-16 hours.

[0013] Further, in step (1), the drying is performed at 60 ℃ - 80 ℃.

[0014] This invention provides an application of CNT@FeCoNi-MXene / MAX material as a microwave absorbing material.

[0015] Furthermore, CNT@FeCoNi-MXene / MAX materials are used as low-frequency absorbing materials.

[0016] The beneficial effects of this invention are:

[0017] 1. The preparation method provided by this invention, through improved synthesis strategies and the combination of MXene / MAX materials and magnetic metal selection, can control the morphology and structure of the material, giving it a higher specific surface area and pore volume. Simultaneously, it increases the interaction opportunities between the absorbing material and electromagnetic waves, improving its absorption performance in the C-band and meeting the requirements for lightweight, low-frequency absorption, and high absorption capacity in absorbing materials. It has excellent application prospects in the field of electromagnetic wave absorption.

[0018] 2. The CNT@FeCoNi-MXene / MAX material prepared in this invention contains CNTs and MXene / MAX materials, and its structure also incorporates magnetic metals. The introduction of CNTs breaks the conductive network, thereby optimizing impedance matching and acting as a barrier to restrict charge movement. The heterogeneous interface between FeCoNi-MXene / MAX and CNTs promotes multiple interface polarizations, and the abundant polar functional groups in MXene / MAX and CNTs provide strong dipole polarization.

[0019] 3. The CNT@FeCoNi-MXene / MAX material prepared in this invention is a composite material prepared by combining a magnetic metal compound as the matrix with a dielectric loss type material. It can not only adjust the complex dielectric constant to meet impedance matching, but also provide additional dielectric loss capability through the interfacial polarization effect of the heterogeneous interface. Combined with the magnetic loss capability of the magnetic metal compound itself, the synthesized CNT@FeCoNi-MXene / MAX material has high absorption capability and low frequency absorption capability as a microwave absorbing material, which is a significant improvement compared with the reported magnetic metal microwave absorbing materials. Moreover, this microwave absorbing material has not been reported in the field of electromagnetic wave absorption. Attached Figure Description

[0020] Figure 1 This is the XRD pattern of the FeCoNi-MXene / MAX material.

[0021] Figure 2 This is a SEM image of the CNT@FeCoNi-MXene / MAX absorbing material.

[0022] Figure 3 This is the XPS full spectrum of the FeCoNi-MXene / MAX material.

[0023] Figure 4 This is the electromagnetic wave absorption curve of the CNT@FeCoNi-MXene / MAX absorbing material. Detailed Implementation

[0024] Example 1: CNT@FeCoNi-MXene / MAX (1:1) microwave absorbing material

[0025] (a) The preparation method is as follows:

[0026] 1. Preparation of FeCoNi-MXene / MAX materials

[0027] Ti3AlC2 (0.5 g, 2.57 mmol), FeCl2·4H2O (1.65 g, 8.30 mmol), CoCl2 (1 g, 7.70 mmol), NiCl2 (1 g, 7.72 mmol), NaCl (0.3 g, 5.13 mmol), and KCl (0.38 g, 5.10 mmol) were ground into powder, mixed evenly, and placed in a tube furnace for etching at 750 °C for 15 h under a nitrogen atmosphere. After naturally cooling to room temperature, the mixture was washed with ultrapure water by vacuum filtration, repeated twice. The resulting product was then dried in a vacuum drying oven at 60 °C for 10 h to obtain the FeCoNi-MXene / MAX material.

[0028] 2. Preparation of CNT@FeCoNi-MXene / MAX (1:1) materials

[0029] The FeCoNi-MXene / MAX material obtained in step 1 and carbon nanotubes (CNTs) were mixed at a mass ratio of 1:1 and placed in an ethanol solution. The mixture was first sonicated for 2 h, then stirred uniformly for 1 h to ensure uniform dispersion. The mixture was then washed with ultrapure water by filtration, repeated twice. The resulting product was dried in a drying oven at 60 °C for 48 h to obtain CNT@FeCoNi-MXene / MAX material with a CNT to FeCoNi-MXene / MAX mass ratio of 1:1.

[0030] (ii) Characterization

[0031] Figure 1 This is the XRD pattern of the FeCoNi-MXene / MAX material, from Figure 1 It can be seen that the peaks emitted by the FeCoNi-MXene / MAX material belong to Ni3Fe, CoTiO3 and CoFe2O4.

[0032] Figure 2 These are SEM images of the CNT@FeCoNi-MXene / MAX material, created by... Figure 2 It can be seen that the morphology of CNT@FeCoNi-MXene / MAX material is a layered structure coated with carbon nanotubes.

[0033] Figure 3 This is the XPS full spectrum of the FeCoNi-MXene / MAX material, from Figure 3 It is evident that the FeCoNi-MXene / MAX material contains elements such as iron, cobalt, nickel, carbon, oxygen, titanium, and aluminum, which proves that iron, cobalt, and nickel elements are incorporated into part of the etched MXene / MAX structure.

[0034] Example 2: CNT@FeCoNi-MXene / MAX (1:2) microwave absorbing material

[0035] (a) The preparation method is as follows:

[0036] 1. Preparation of FeCoNi-MXene / MAX

[0037] Same as Example 1.

[0038] 2. Preparation of CNT@FeCoNi-MXene / MAX (1:2) materials

[0039] The FeCoNi-MXene / MAX material obtained in step 1 and carbon nanotubes (CNTs) were mixed at a mass ratio of 1:2 and placed in an ethanol solution. The mixture was first sonicated for 2 h, then stirred uniformly for 1 h to ensure uniform dispersion. The mixture was then washed with ultrapure water by vacuum filtration, repeated twice. The resulting product was dried in a drying oven at 60 °C for 48 h to obtain CNT@FeCoNi-MXene / MAX material with a CNT to FeCoNi-MXene / MAX mass ratio of 1:2.

[0040] Example 3: Application of CNT@FeCoNi-MXene / MAX material as a microwave absorbing material

[0041] The CNT@FeCoNi-MXene / MAX materials prepared in Examples 1 and 2 were used in the field of electromagnetic wave absorption.

[0042] The method is as follows: This experiment used a vector network analyzer. 80 mg of sample was dispersed in 320 mg of melted paraffin. After cooling to room temperature, the mixture was pressed into rings with an inner diameter of 3.04 mm, an outer diameter of 7 mm, and a thickness of 2 mm–5 mm. A coaxial fixture was used for testing. The electromagnetic parameters and S-parameters of the sample were measured using a vector network analyzer (Agilent 5234A) to calculate the electromagnetic wave absorption parameters. The results are shown in Table 1.

[0043] Table 1

[0044] As shown in Table 1, when the mass ratio of CNT@FeCoNi-MXene / MAX is 1:1, the minimum reflection loss RL is... min It reaches -68.15 dB with an effective absorption bandwidth (EAB) of 3.87 GHz; at a quality ratio of 1:2, RL min The impedance is -65.51 dB, and the EAB is wide up to 4.77 GHz. While both exhibit excellent electromagnetic wave absorption performance, the RL with a mass ratio of 1:1... min The absolute value of the mass ratio is larger, and the absorption capacity of electromagnetic waves is stronger. Therefore, the preferred mass ratio of the present invention is 1:1.

[0045] Figure 4 The electromagnetic wave absorption parameters of CNT@FeCoNi-MXene / MAX material with a filler content of 20% are derived from... Figure 4 As can be seen, the minimum reflection loss is -68.15 dB, corresponding to a thickness of 3.11 mm and a frequency of 6.94 GHz; at the same time, the maximum EAB at a thickness of 1.48 mm is 3.87 GHz, indicating that the absorbing material can achieve efficient absorption with a minimum reflection loss of -68.15 dB in the low-frequency C band, and the thickness can be adjusted to achieve full-band coverage.

Claims

1. A CNT@FeCoNi-MXene / MAX material, characterized in that, The material is CNT@FeCoNi-MXene / MAX, which is made by etching MXene-doped magnetic iron-cobalt-nickel composite carbon nanotubes with molten salt; by mass ratio, CNT:FeCoNi-MXene / MAX = 1:(0.5-2).

2. The CNT@FeCoNi-MXene / MAX material according to claim 1, characterized in that, By mass ratio, CNT:FeCoNi-MXene / MAX = 1:

1.

3. A method for preparing a CNT@FeCoNi-MXene / MAX material according to claim 1 or 2, characterized in that, The preparation method includes the following steps: (1) Take Ti3AlC2, iron salt, cobalt salt, nickel salt and flux, grind them into powder, mix them evenly, place them in a tube furnace, etch them at high temperature under nitrogen atmosphere, cool them naturally to room temperature, wash them with ultrapure water, filter them and dry them to obtain FeCoNi-MXene / MAX material; (2) The FeCoNi-MXene / MAX material obtained in step (1) and carbon nanotubes (CNTs) are placed in an ethanol solution, ultrasonically stirred and mixed, washed with ultrapure water, filtered and dried to obtain CNT@FeCoNi-MXene / MAX material.

4. The method for preparing CNT@FeCoNi-MXene / MAX material according to claim 3, characterized in that, The iron salt is FeCl2·4H2O; the cobalt salt is CoCl2; the nickel salt is NiCl2; and the flux is NaCl and KCl.

5. The method for preparing CNT@FeCoNi-MXene / MAX material according to claim 4, characterized in that, The molar ratio is Ti3AlC2:FeCl2·4H2O:CoCl2:NiCl2:NaCl:KCl=1:(3-10):(3-6):(3-6):2:

2.

6. The method for preparing CNT@FeCoNi-MXene / MAX material according to claim 5, characterized in that, The molar ratio is Ti3AlC2:FeCl2·4H2O:CoCl2:NiCl2:NaCl:KCl = 1:3:3:3:2:

2.

7. The method for preparing CNT@FeCoNi-MXene / MAX material according to claim 3, characterized in that, In step (1), the high-temperature etching is performed at 700 ℃ - 800 ℃ for 15 h - 16 h.

8. The method for preparing CNT@FeCoNi-MXene / MAX material according to claim 3, characterized in that, In step (1), the drying is performed at 60 ℃ - 80 ℃.

9. The application of the CNT@FeCoNi-MXene / MAX material as described in claim 1 or 2 as a microwave absorbing material.

10. The application according to claim 9, characterized in that, Application of CNT@FeCoNi-MXene / MAX materials as low-frequency absorbing materials.

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