Hollow nanocage@micronanowire heterostructure material and application thereof in dual-band electromagnetic wave absorption
By synthesizing a hollow nanocage@micro/nanowire heterostructure material using MOF derivatives as templates, the problem of poor electromagnetic absorption performance in the dual-band frequency range was solved, achieving wide-band electromagnetic wave absorption and loss characteristics, with good impedance matching and dielectric-magnetic synergistic effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEFEI UNIV OF TECH
- Filing Date
- 2023-08-23
- Publication Date
- 2026-06-16
Smart Images
Figure HDA0004408258170000011 
Figure HDA0004408258170000012 
Figure HDA0004408258170000013
Abstract
Description
Technical Field
[0001] This invention relates to the field of micro / nano composite material control and preparation technology and dual-band electromagnetic wave absorption functional material technology, specifically to a method for preparing a hollow nanocage@micro / nanowire heterostructure material and its application in dual-band electromagnetic wave absorption. Background Technology
[0002] With the rapid development of information technology, electromagnetic radiation and interference at various frequencies in space have inevitably intensified, attracting widespread attention. Therefore, there is an urgent need to explore efficient electromagnetic wave absorbing materials to decompose unwanted electromagnetic energy into other forms, avoiding secondary electromagnetic pollution. High-performance electromagnetic wave (EMW) absorbing materials need to meet suitable impedance matching conditions and strong attenuation characteristics. Considering the need to achieve multi-band electromagnetic wave absorption, the rational design of the composition and nanostructure of microwave absorbing materials becomes crucial for the comprehensive application of various attenuation mechanisms in the electromagnetic energy conversion process. However, rationally constructing special heterostructures with synergistic loss mechanisms to optimize dual-band electromagnetic absorption performance remains a significant challenge.
[0003] Metal-organic framework (MOF) derivatives are a novel type of functional material for absorbing electromagnetic waves. Their customizable microstructure, controllable composition, high porosity, and multifunctionality offer significant advantages for constructing superior electromagnetic wave absorbing materials. First, the customizability of MOF microstructure and composition allows for the tuning of electromagnetic parameters and accelerated dissipation. In particular, hollow structures, yolk-shell structures, and layered porous structures further optimize impedance matching and multiple reflections, exacerbating electromagnetic wave energy loss. Second, self-templating pyrolysis methods can fabricate electromagnetic wave absorbing materials with dielectric-magnetic multiple loss capabilities. Third, the layered porous structure of MOF-derived materials provides lightweight properties, excellent impedance matching performance, and multiple reflection capabilities. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing a hollow nanocage@micro / nanowire heterostructure material and its application in dual-band electromagnetic wave absorption. This invention synthesizes a hollow nanocage@micro / nanowire heterostructure material using a target MOF with a specific structure as a template. Because the hollow nanocage is loaded onto the surface of the micro / nanowires, the impedance matching of the overall material is optimized. The combination of the porous carbon matrix and the internally distributed cobalt nanoparticles brings excellent dielectric-magnetic synergistic effects, which will contribute to a wider absorption bandwidth and stronger reflection loss, making it suitable for electromagnetic wave absorption in dual-band environments.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] A method for preparing a hollow nanocage@micro / nanowire heterostructure material includes the following steps:
[0007] (1) Dissolve 1,3,5-benzenetricarboxylic acid in deionized water to form solution A; dissolve cobalt acetate tetrahydrate in deionized water to form solution B; add solution B to solution A, then place in an oil bath and stir to react. The resulting product is centrifuged, washed and dried to obtain Co-BTC micro-nano wire powder.
[0008] (2) 2-methylimidazole and the Co-BTC micro / nanowire powder were uniformly dispersed in methanol to form solution C; cobalt nitrate hexahydrate was dissolved in methanol to form solution D; solution D was added to solution C to react, and the resulting product was centrifuged, washed and dried to obtain solid nanoparticles@micro / nanowire structure material;
[0009] (3) The solid nanoparticles@micro-nanowire structure material and 2,5-dihydroxyterephthalic acid were uniformly dispersed in N,N-dimethylformamide. The resulting mixed solution was transferred to a high-pressure reactor for reaction, followed by centrifugation, washing and drying to obtain hollow nanocages@micro-nanowire precursor material.
[0010] (4) The hollow nanocage@micro-nanowire precursor material is pyrolyzed at high temperature to obtain the hollow nanocage@micro-nanowire heterostructure material.
[0011] Preferably, in step (1), the concentration of 1,3,5-benzenetricarboxylic acid in the mixture of solution A and solution B is 10-50 mmol / L, the solubility of cobalt acetate tetrahydrate is 2-25 mmol / L, and the volume ratio of solution A to solution B is 9:1.
[0012] Preferably, in step (1), the temperature in the oil bath is 80-100℃, and the stirring reaction time is 1-20 min.
[0013] Preferably, in step (2): the ratio of 2-methylimidazole, Co-BTC micro / nanowire powder and methanol in solution C is 0.03-0.3 mol: 50-300 mg: 30 mL, the concentration of cobalt nitrate hexahydrate in the mixture of solution C and solution D is 20-300 mmol / L, and the volume ratio of methanol in solution C to solution D is 3:1.
[0014] Preferably, in step (2), the reaction temperature is room temperature and the reaction time is 15-50 min.
[0015] Preferably, in step (3), the ratio of solid nanoparticles@micro / nanowire structure material, 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide is 50-300 mg: 0.1-1.25 mmol: 50 mL.
[0016] Preferably, in step (3), the reaction is carried out in an oven at 90-150°C for 300-700 min.
[0017] Preferably, in steps (1), (2), and (3), the washing is performed with ethanol 2-4 times, and the drying is performed in an oven at 60-85°C.
[0018] Preferably, in step (4), the temperature of the high-temperature pyrolysis is 600-800℃, the holding time is 2-4h, and the heating rate is 2-5℃ / min.
[0019] The present invention also provides the use of the hollow nanocage@micro / nanowire heterostructure material, which is suitable for electromagnetic wave absorption in dual frequency bands of 2GHz-18GHz and 26.5GHz-40GHz.
[0020] Compared with the prior art, the beneficial effects of the present invention are reflected in:
[0021] 1. The hollow nanocage@micro / nanowire heterostructure material prepared by this invention, through the structural design of a special MOF precursor, utilizes the combination of one-dimensional micro / nanowires and hollow nanocages to fully leverage the advantages of controllable microstructure and heteroatom doping of MOF materials. Through subsequent high-temperature pyrolysis, especially to achieve good impedance matching, the synergy between dielectric loss and magnetic loss is achieved, resulting in excellent dual-band electromagnetic wave attenuation capability.
[0022] 2. The hollow nanocage@micro / nanowire heterostructure material prepared in this invention is applied to electromagnetic wave absorption in dual-band. The hollow nanocage covering the surface of the one-dimensional micro / nanowire can significantly improve the impedance matching of the overall material, allowing electromagnetic waves of a wider frequency band to enter the material and be lost. The overall one-dimensional porous carbon structure increases the probability of material overlap, thereby improving the overall conduction loss. The material has abundant heterostructure interfaces, including hollow nanocage-micro / nanowire and porous carbon-cobalt nanoparticles, providing abundant polarization loss and dipole polarization. The overall one-dimensional porous carbon structure and the internally dispersed cobalt nanoparticles can not only form a dielectric-magnetic synergistic effect, but the dispersed cobalt nanoparticles can also generate multiple magnetic losses, giving the material excellent attenuation characteristics in dual-band electromagnetic wave absorption.
[0023] 3. This invention further enriches the microstructure library of MOF materials and expands the application fields of MOF-derived heterostructure materials. By designing the structure of MOF precursors, uniquely structured MOF-derived carbon-based composite materials can be obtained through subsequent pyrolysis strategies. Utilizing the advantages of MOF materials, such as controllable component microstructure and heteroatom doping, gives them greater practical value in fields such as electromagnetic wave absorption, separation, catalysis, and energy storage.
[0024] 4. The preparation method of the present invention is easy to operate, green, environmentally friendly and pollution-free, and low in cost, and has broad application prospects. Attached Figure Description
[0025] Figure 1 (a) FESEM image and (b) TEM image of the hollow nanocage@micro / nanowire heterostructure material prepared in Example 1.
[0026] Figure 2 (a) FESEM image and (b) TEM image of the hollow nanocage@micro / nanowire heterostructure material prepared in Example 2.
[0027] Figure 3 (a) FESEM image and (b) TEM image of the hollow nanocage@micro / nanowire heterostructure material prepared in Example 3.
[0028] Figure 4 The XRD diffraction patterns are those of the hollow nanocage@micro / nanowire heterostructure materials prepared in Examples 1-3, where S-1 is the sample obtained in Example 1, S-2 is the sample obtained in Example 2, and S-3 is the sample obtained in Example 3.
[0029] Figure 5 The three-dimensional reflection loss diagrams and effective absorption bandwidth values of the hollow nanocage@micro / nanowire heterostructure material prepared in Example 1 are shown in the dual frequency bands of 2-18 GHz (a) and 26.5-40 GHz (b).
[0030] Figure 6 The three-dimensional reflection loss diagrams and effective absorption bandwidth values of the hollow nanocage@micro / nanowire heterostructure material prepared in Example 2 are shown in the dual frequency bands of 2-18 GHz (a) and 26.5-40 GHz (b).
[0031] Figure 7 The three-dimensional reflection loss diagrams and effective absorption bandwidth values of the hollow nanocage@micro / nanowire heterostructure material prepared in Example 3 are shown in the dual frequency bands of 2-18 GHz (a) and 26.5-40 GHz (b). Detailed Implementation
[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0033] Example 1
[0034] A method for preparing a hollow nanocage@micro / nanowire heterostructure material includes the following steps:
[0035] (1) Dissolve 0.42 g (2 mmol) of 1,3,5-benzenetricarboxylic acid in 90 mL of deionized water to form solution A, and dissolve 0.54 g (3.05 mmol) (2.17 mmol) of cobalt acetate tetrahydrate in 10 mL of deionized water to form solution B. Add solution B to solution A and react in an oil bath at 100 °C for 10 min. After centrifuging and washing the products, dry them in an oven at 80 °C to obtain Co-BTC micro-nano wire powder.
[0036] (2) 8 g (97.4 mmol) of 2-methylimidazole and 83 mg of Co-BTC micro / nanowire powder were uniformly dispersed in 30 mL of methanol to form solution C. 0.3 g (1.03 mmol) of cobalt nitrate hexahydrate was dissolved in 10 mL of methanol to form solution D. Solution D was added to solution C, and the reaction was carried out at room temperature for 15 min. The products were centrifuged, washed, and dried in an 80 °C oven to obtain solid nanoparticles@micro / nanowire powder.
[0037] (3) 100 mg of solid nanoparticles@micro-nanowire powder and 100 mg (0.5 mmol) of 2,5-dihydroxyterephthalic acid were uniformly dispersed in 50 mL of N,N-dimethylformamide; the mixed solution was transferred to a high-pressure reactor and then placed in an oven at 130 °C for 500 min. The products were centrifuged and washed clean, and then dried in an oven at 80 °C to obtain hollow nanocage@micro-nanowire precursor material powder.
[0038] (4) The hollow nanocage@micro-nanowire precursor material was annealed under argon protection at 600℃ for 2 hours and the heating rate was 2℃ / min to obtain the hollow nanocage@micro-nanowire heterostructure material, which was labeled as S-1.
[0039] Figure 1 (a) FESEM image and (b) TEM image of the hollow nanocage@micro / nanowire heterostructure material prepared in this embodiment. Figure 1 (a) It can be seen that after pyrolysis, uniform nanocages are dispersed on one-dimensional micro / nanowire porous carbon, by Figure 1 As can be seen in (b), the nanocage is hollow, and the cobalt nanoparticles are uniformly and diffusely distributed inside the whole material. Figure 4 S-1 in the figure represents the XRD diffraction pattern of the hollow nanocage@micro / nanowire heterostructure material prepared in this embodiment, which confirms that the material contains cobalt nanoparticles.
[0040] Example 2
[0041] In this embodiment, hollow nanocage@micro / nanowire heterostructure material was prepared using the same method as in Example 1. The only difference was that the annealing temperature in step (4) was 700℃. The resulting hollow nanocage@micro / nanowire heterostructure material was labeled as S-2.
[0042] Figure 2 (a) FESEM image and (b) TEM image of the hollow nanocage@micro / nanowire heterostructure material prepared in this embodiment. Figure 2 (a) It can be seen that after pyrolysis, uniform nanocages are dispersed on one-dimensional micro / nanowire porous carbon, by Figure 2 As can be seen in (b), the nanocage is hollow and the cobalt nanoparticles are uniformly and diffusely distributed inside the whole material, but they are slightly larger than S-1. Figure 4 S-2 in the figure is the XRD diffraction pattern of the hollow nanocage@micro / nanowire heterostructure material prepared in this embodiment, which confirms that the material contains cobalt nanoparticles.
[0043] Example 3
[0044] In this embodiment, hollow nanocage@micro / nanowire heterostructure material was prepared using the same method as in Example 1. The only difference was that the annealing temperature in step (4) was 800℃. The resulting hollow nanocage@micro / nanowire heterostructure material was labeled as S-3.
[0045] Figure 3 (a) FESEM image and (b) TEM image of the hollow nanocage@micro / nanowire heterostructure material prepared in this embodiment. Figure 3 (a) It can be seen that after pyrolysis, uniform nanocages are dispersed on one-dimensional micro / nanowire porous carbon, by Figure 3 As can be seen in (b), the nanocage is hollow and the cobalt nanoparticles are distributed inside the whole material. However, as the carbonization temperature increases, the cobalt nanoparticles show obvious agglomeration and growth compared to samples S-1 and S-2. Figure 4 S-3 in the figure represents the XRD diffraction pattern of the hollow nanocage@micro / nanowire heterostructure material prepared in this embodiment, which confirms that the material contains cobalt nanoparticles.
[0046] Example 4
[0047] Performance testing of hollow nanocage@micro / nanowire heterostructure materials in dual-band electromagnetic wave absorption:
[0048] (1) Hollow nanocage@micro-nanowire heterostructure material powder and paraffin were uniformly mixed at a mass ratio of 1:4 and pressed into a coaxial ring sample with an inner diameter of 3.04 mm and an outer diameter of 7.00 mm. The electromagnetic parameters in the 2-18 GHz frequency band were tested using the coaxial method. The sample was pressed into a block sample with a length of 7.11 mm and a width of 3.56 mm. The electromagnetic parameters in the 26.5-40 GHz frequency band were tested using the waveguide method. The performance parameters of reflection loss were obtained by calculation and simulation.
[0049] Figure 5 , Figure 6 , Figure 7 The figures show the three-dimensional reflection loss diagrams and effective absorption bandwidth values of the hollow nanocage@micro / nanowire heterostructure materials obtained in Examples 1, 2, and 3, respectively, in the 2-18 GHz (a) and 26.5-40 GHz (b) frequency bands. It can be seen that the obtained hollow nanocage@micro / nanowire heterostructure materials exhibit good broadband electromagnetic wave absorption performance in both the 2-18 GHz and 26.5-40 GHz frequency bands.
[0050] in:
[0051] The performance parameters of the hollow nanocage@micro / nanowire heterostructure material (S-1) designed in Example 1 are as follows: In the 2-18 GHz frequency band, the maximum reflection loss can reach -27.1 dB with a thickness of 6.1 mm, and the effective absorption bandwidth can reach 4.5 GHz with a thickness of 6.8 mm; In the 26.5-40 GHz frequency band, the maximum reflection loss can reach -38.3 dB with a thickness of 3.8 mm, and the effective absorption bandwidth can reach 6.8 GHz with a thickness of 3.1 mm; Under the overall dual-band (total bandwidth of 30.5 GHz), the effective absorption frequency band coverage of S-1 reaches 37%.
[0052] The performance parameters of the hollow nanocage@micro / nanowire heterostructure material (S-2) designed in Example 2 are as follows: In the 2-18 GHz frequency band, the maximum reflection loss reaches -52.2 dB with a thickness of 8.6 mm, and the effective absorption bandwidth reaches 4.5 GHz with a thickness of 1.8 mm; in the 26.5-40 GHz frequency band, the maximum reflection loss reaches -18.4 dB with a thickness of 2.4 mm, and the effective absorption bandwidth reaches 4.8 GHz with a thickness of 2.2 mm; under the overall dual-band (total bandwidth of 30.5 GHz), the effective absorption frequency band coverage of S-2 reaches 30%.
[0053] The performance parameters of the hollow nanocage@micro / nanowire heterostructure material (S-3) designed in Example 3 are as follows: In the 2-18 GHz frequency band, the maximum reflection loss can reach -16.2 dB with a thickness of 7.9 mm, and the effective absorption bandwidth can reach 4.4 GHz with a thickness of 5.8 mm; In the 26.5-40 GHz frequency band, the maximum reflection loss can reach -52.2 dB with a thickness of 7.0 mm, and the effective absorption bandwidth can reach 2.5 GHz with a thickness of 6.6 mm; Under the overall dual-band (total bandwidth of 30.5 GHz), the effective absorption frequency band coverage of S-3 reaches 23%.
[0054] In summary, it can be seen that the reasonable material structure design and appropriate pyrolysis temperature in Example 1 are beneficial to improving the overall dual-band electromagnetic wave absorption performance.
[0055] The superior dual-band electromagnetic wave absorption performance of hollow nanocage@micro / nanowire heterostructure materials (especially S-1) is mainly attributed to the following: the hollow nanocage uniformly covering the surface of one-dimensional micro / nanowires significantly improves the impedance matching of the overall material, allowing electromagnetic waves of a wider frequency band to enter the material and be lost; the overall one-dimensional porous carbon structure increases the probability of material overlap, improving the overall conduction loss; the material has abundant heterostructure interfaces, including hollow nanocage-micro / nanowires and porous carbon-cobalt nanoparticles, providing abundant polarization loss and dipole polarization; the overall one-dimensional porous carbon structure and the internally dispersed cobalt nanoparticles not only form a dielectric-magnetic synergistic effect, but the dispersed cobalt nanoparticles can also generate multiple magnetic losses, enabling the material to exhibit excellent attenuation characteristics in dual-band electromagnetic wave absorption.
[0056] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the present invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.
Claims
1. A method for preparing a hollow nanocage@micro / nanowire heterostructure material, characterized in that, Includes the following steps: (1) Dissolve 1,3,5-benzenetricarboxylic acid in deionized water to form solution A; dissolve cobalt acetate tetrahydrate in deionized water to form solution B; add solution B to solution A, then place it in an oil bath and stir to react. The resulting product is centrifuged, washed and dried to obtain Co-BTC micro-nano wire powder. (2) 2-methylimidazole and the Co-BTC micro / nanowire powder are uniformly dispersed in methanol to form solution C; cobalt nitrate hexahydrate is dissolved in methanol to form solution D; solution D is added to solution C to react, and the resulting product is centrifuged, washed and dried to obtain solid nanoparticles@micro / nanowire structure material; (3) The solid nanoparticles@micro / nanowire structure material and 2,5-dihydroxyterephthalic acid were uniformly dispersed in N,N-dimethylformamide. The resulting mixed solution was transferred to a high-pressure reactor and reacted in an oven at 90-150 °C for 300-700 min. Afterwards, it was centrifuged, washed, and dried to obtain the hollow nanocages@micro / nanowire precursor material. The ratio of solid nanoparticles@micro / nanowire structure material, 2,5-dihydroxyterephthalic acid, and N,N-dimethylformamide was 50-300 mg: 0.1-1.25 mmol: 50 mL. (4) The hollow nanocage@micro-nanowire precursor material is pyrolyzed at high temperature to obtain the hollow nanocage@micro-nanowire heterostructure material; the high temperature of the pyrolysis is 600-800 ℃, the holding time is 2-4 h, and the heating rate is 2-5 ℃ / min.
2. The method for preparing the hollow nanocage@micro / nanowire heterostructure material according to claim 1, characterized in that: In step (1), the concentration of 1,3,5-benzenetricarboxylic acid in the mixture of solution A and solution B is 10-50 mmol / L, the solubility of cobalt acetate tetrahydrate is 2-25 mmol / L, and the volume ratio of solution A to solution B is 9:
1.
3. The method for preparing the hollow nanocage@micro / nanowire heterostructure material according to claim 1, characterized in that: In step (1), the temperature in the oil bath is 80-100 ℃, and the stirring reaction time is 1-20 min.
4. The method for preparing the hollow nanocage@micro / nanowire heterostructure material according to claim 1, characterized in that, In step (2): the ratio of 2-methylimidazole, Co-BTC micro / nanowire powder and methanol in solution C is 0.03-0.3 mol: 50-300 mg: 30 mL, and the concentration of cobalt nitrate hexahydrate in the mixture of solution C and solution D is 20-300 mmol / L; the volume ratio of methanol in solution C to solution D is 3:
1.
5. The method for preparing the hollow nanocage@micro / nanowire heterostructure material according to claim 1, characterized in that: In step (2), the reaction temperature is room temperature and the reaction time is 15-50 min.
6. A hollow nanocage@micro / nanowire heterostructure material prepared by the preparation method according to any one of claims 1 to 5.
7. The use of the hollow nanocage@micro / nanowire heterostructure material according to claim 6, characterized in that: The hollow nanocage@micro-nanowire heterostructure material is suitable for electromagnetic wave absorption in both the 2 GHz-18 GHz and 26.5 GHz-40 GHz frequency bands.