Preparation and application of one-dimensional rod-like nitrogen-doped porous carbon matrix coated co-ni nanoparticle composite derived from mofs

Abstract

The application discloses a preparation method and application of a MOF-derived one-dimensional rod-shaped nitrogen-doped porous carbon matrix coated CoNi alloy nanoparticle composite material, and forms a nitrogen-doped MOF@MOF structure through structure and component design of the MOF, and obtains a nitrogen-doped porous carbon matrix coated magnetic CoNi alloy nanoparticle composite material in a dispersed distribution after annealing. The composite material has excellent dielectric-magnetic synergistic effect and impedance matching performance, which is beneficial to wider electromagnetic wave absorption bandwidth, lower matching thickness and lower load, and is suitable for electromagnetic wave absorption under double-wave bands (centimeter wave and millimeter wave).

Description

Technical Field

[0001] This invention belongs to the fields of micro / nano composite material control synthesis technology and electromagnetic wave absorption functional material technology, specifically relating to the preparation and application of a MOF-derived one-dimensional rod-shaped nitrogen-doped porous carbon matrix coated with CoNi nanoparticles. Background Technology

[0002] With the rapid development of information technology, especially the arrival of the 5G era, the number of electromagnetic wave emission and interference sources has increased. A large amount of electromagnetic wave radiation across multiple frequency bands has penetrated into the environment surrounding humans, causing major problems of widespread concern in contemporary society, such as electromagnetic interference, radiation pollution, and information leakage. Ideal electromagnetic wave absorbing materials should be lightweight, flexible, efficient, broadband, and have low load characteristics. However, under normal circumstances, absorption under different electromagnetic wave frequency bands requires constantly replacing various absorbing materials or fabricating multi-layered structures, making them difficult to apply in complex electromagnetic wave environments.

[0003] Metal-organic frameworks (MOFs), as a novel class of porous crystalline materials, consist of inorganic metal centers (metal ions or metal clusters) and organic ligands linked by self-assembly. In electromagnetic wave absorbing materials, specific MOFs can be designed and synthesized to combine dielectric and magnetic loss materials, forming a dielectric-magnetic synergistic effect and improving impedance matching. However, pure MOFs have very low conductivity and dielectric properties, failing to meet impedance matching requirements. To improve conductivity and electromagnetic response, the most common method is to anneal the MOF precursor to obtain metal / porous carbon-based nanostructures. However, annealing simple pure MOF structures usually involves the aggregation and growth of metal particles. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and applying a MOF-derived one-dimensional rod-shaped nitrogen-doped porous carbon matrix coated with CoNi nanoparticles.

[0005] By designing the MOF precursor structure, the resulting metal and carbon-based components can be uniformly dispersed within a periodic MOF-derived framework, effectively preventing the aggregation and growth of metal nanoparticles. Simultaneously, nitrogen doping of the carbon component further enhances dipole and interfacial polarization, thereby improving dielectric loss and enhancing the material's electromagnetic wave absorption performance over a wide bandwidth. Furthermore, this invention, through structural and compositional design of MOFs, forms a nitrogen-doped MOF@MOF structure. After annealing, a composite material of dispersed magnetic CoNi alloy nanoparticles coated with a nitrogen-doped porous carbon matrix is ​​obtained. This composite material exhibits excellent dielectric-magnetic synergy and impedance matching performance, which will benefit a wider electromagnetic wave absorption bandwidth, lower matching thickness, and lower loading, making it suitable for electromagnetic wave absorption in both centimeter and millimeter waves.

[0006] This method is simple, environmentally friendly, and low-cost, and has broad application prospects in dual-band electromagnetic wave absorption.

[0007] The present invention discloses a method for preparing a MOF-derived one-dimensional rod-shaped nitrogen-doped porous carbon matrix coated with CoNi nanoparticles, comprising the following steps:

[0008] (1) Add 2,5-dihydroxyterephthalic acid and sodium hydroxide to deionized water to obtain solution A. Place solution A in an oil bath and heat and stir magnetically.

[0009] (2) Cobalt chloride hexahydrate and nickel chloride hexahydrate were added to deionized water to obtain solution B;

[0010] (3) Slowly add solution B to solution A, place it in an oil bath and heat and stir to react, centrifuge, wash and dry the product to obtain Co / Ni-MOF-74 nanorod powder;

[0011] (4) Dissolve 2-methylimidazole in methanol, then add Co / Ni-MOF-74 nanorod powder and disperse it evenly, and denote it as solution C;

[0012] (5) Dissolve zinc nitrate hexahydrate in methanol and denote the solution as solution D;

[0013] (6) Slowly add solution D to solution C, stir the reaction magnetically, centrifuge, wash and dry the product to obtain Co / Ni-MOF-74@ZIF-8 nanorod powder;

[0014] (7) The obtained Co / Ni-MOF-74@ZIF-8 nanorod powder was annealed under argon protection to obtain a nitrogen-doped porous carbon matrix coated CoNi alloy nanoparticle composite material.

[0015] Preferably, in step (1), the concentration of 2,5-dihydroxyterephthalic acid in solution A is 10-50 mmol / L, the concentration of sodium hydroxide is 10-50 mmol / L, and the volume of solution A is 90 mL.

[0016] Preferably, in step (1), the heating temperature is 80-100℃.

[0017] Preferably, in step (2), the concentration of cobalt chloride hexahydrate in solution B is 2-40 mmol / L, the concentration of nickel chloride hexahydrate is 2-40 mmol / L, and the volume of solution B is 10 mL.

[0018] Preferably, in step (3), the heating temperature is 80-100℃ and the reaction time is 30-60min.

[0019] Preferably, in step (4), the concentration of 2-methylimidazole in solution C is 400-800 mmol / L, the concentration of Co / Ni-MOF-74 nanorod powder is 8-16 mmol / L, and the volume of solution A is 20 mL.

[0020] Preferably, in step (5), the concentration of zinc nitrate hexahydrate in solution D is 20-40 mmol / L, and the volume of solution D is 5 mL.

[0021] Preferably, in step (6), the reaction time is 15-30 min.

[0022] Preferably, in steps (3) and (6), after washing with ethanol 2-4 times, the product is dried in an oven at 75-85°C.

[0023] Preferably, in step (7), the annealing temperature is 600-800℃, the holding time is 2-4h, and the heating rate is 2-5℃ / min.

[0024] The application of the one-dimensional rod-shaped nitrogen-doped porous carbon matrix-coated CoNi nanoparticle composite material prepared by this invention is to use the composite material as an electromagnetic wave absorbing material for electromagnetic wave absorption in the centimeter wave (2GHz-18GHz) or millimeter wave (26.5GHz-40GHz) frequency bands.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. The present invention prepares a one-dimensional rod-shaped nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material. It utilizes the combination of metal ions and specific organic ligands to form specific bimetallic Co / Ni-MOF-74 nanorods, and then coats the surface of them with a layer of ZIF-8 particles to prepare a special structure of nitrogen-doped MOF@MOF. Subsequently, the Co / Ni-MOF-74@ZIF-8 nanorods are pyrolyzed at high temperature in an inert atmosphere to obtain the nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material. This fully utilizes the advantages of MOF material composition microstructure controllability, heteroatom doping, and metal dispersion in the carbon matrix. In particular, it achieves good impedance matching between dielectric loss and magnetic loss, thereby obtaining excellent dual-band electromagnetic wave attenuation capability.

[0027] 2. The one-dimensional rod-shaped nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material prepared by this invention has a one-dimensional rod-shaped nitrogen-doped porous carbon framework, which can leverage the advantages of heteroatom doping in carbon materials to improve the overall dielectric loss. At the same time, its porous structure can accelerate the attenuation of electromagnetic waves by increasing the number of reflections of electromagnetic waves in the channel and the contact probability between the absorber and the electromagnetic wave. Nitrogen doping on the surface of the porous carbon framework can improve the impedance matching performance of the material, and the uniformly dispersed magnetic CoNi alloy nanoparticles provide magnetic loss derived from magnetic resonance. Meanwhile, nitrogen-doped porous carbon provides abundant heterostructures, improving the interfacial polarization and dipole polarization loss of the overall material and enhancing the electromagnetic wave absorption performance in both centimeter-wave and millimeter-wave bands.

[0028] 3. This invention further expands the application fields of MOF materials with special structures. MOFs, as ideal sacrificial precursors, are used to synthesize highly dispersed magnetic metal alloys / heteroatom-doped carbon-based composite materials through a calcination thermal decomposition strategy. Utilizing the advantages of MOF materials, such as controllable component microstructure and heteroatom and dispersed magnetic metal doping, they have greater practical application value in fields such as electromagnetic wave absorption, separation, sensing, and energy storage.

[0029] 4. The preparation method of the present invention is simple and easy to operate, green, environmentally friendly and pollution-free, and low in cost. Attached Figure Description

[0030] Figure 1 The images show (a) FESEM image, (b) FESEM image, (c) nitrogen element distribution map, and (b) TEM image of the nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material prepared in Example 1.

[0031] Figure 2 The images shown are: (a) FESEM image of the precursor of the nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material prepared in Example 2; (b) FESEM image; (c) nitrogen element distribution map; and (d) TEM image.

[0032] Figure 3 The XRD diffraction patterns of (a) the precursor of the nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material prepared in Examples 1-2 and (b) the XRD diffraction patterns of the nitrogen-doped porous carbon matrix-coated CoNi nanoparticle composite material are shown in Examples 1-2. S-1 is Example 1 and S-2 is Example 2.

[0033] Figure 4 The three-dimensional reflection loss diagrams of the nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material obtained in Example 1 with a mass ratio of 2:8 to paraffin wax in the centimeter wave (2-18GHz) (a) and millimeter wave (26.5-40GHz) (b) frequency bands are shown.

[0034] Figure 5 The three-dimensional reflection loss diagrams of the nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material obtained in Example 1 with a mass ratio of 3:7 to paraffin wax in the centimeter wave (2-18GHz) (a) and millimeter wave (26.5-40GHz) (b) frequency bands are shown.

[0035] Figure 6 The three-dimensional reflection loss diagrams of the nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material obtained in Example 2, with a mass ratio of 2:8 to paraffin, are shown in the centimeter wave (2-18GHz) (a) and millimeter wave (26.5-40GHz) (b) frequency bands, respectively.

[0036] Figure 7 The three-dimensional reflection loss diagrams of the nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material obtained in Example 2, with a mass ratio of 3:7 to paraffin, are shown in the centimeter wave (2-18GHz) (a) and millimeter wave (26.5-40GHz) (b) frequency bands. Detailed Implementation

[0037] 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 them. 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.

[0038] Example 1:

[0039] The preparation method of the one-dimensional rod-shaped nitrogen-doped porous carbon matrix coated CoNi alloy nanoparticle composite material in this embodiment includes the following steps:

[0040] (1) Dissolve 0.396 g of 2,5-dihydroxyterephthalic acid and 180 mg of sodium hydroxide in 90 ml of deionized water to form solution A. Dissolve 0.476 g of cobalt chloride hexahydrate and 0.475 g of nickel chloride hexahydrate 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 60 min. After centrifugation, washing, and drying, obtain Co. 0.5 Ni 0.5 -MOF-74 nanorod powder.

[0041] (2) Dissolve 1.5g of 2-methylimidazole in 20ml of methanol, then add 102.5mg of Co. 0.5 Ni 0.5MOF-74 nanorod powder was dispersed evenly to obtain solution C; 0.2 g of zinc nitrate hexahydrate was dissolved in 5 ml of methanol to obtain solution D; solution D was slowly added to solution C, and the reaction was carried out with magnetic stirring. The product was centrifuged, washed, and dried to obtain...

[0042] Co 0.5 Ni 0.5 -MOF-74@ZIF-8 nanorod powder.

[0043] (3) Co 0.5 Ni 0.5 -MOF-74@ZIF-8 nanorod powder was annealed at 600℃ under argon protection for 2 hours with a heating rate of 2℃ / min to obtain a one-dimensional rod-shaped nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material, labeled as S-1.

[0044] Figure 1 The images shown are (a) FESEM image of the precursor, (b) FESEM image, (c) nitrogen elemental distribution map, and (b) TEM image in this embodiment. Figure 1 (a) and Figure 3 (a) The XRD diffraction pattern of the precursor shows that a layer of ZIF-8 particles was successfully coated on the precursor. Figure 1 As shown in (bd), after pyrolysis, nitrogen has been successfully introduced into the carbon matrix. The magnetic CoNi alloy nanoparticles are uniformly and diffusely distributed within the porous carbon framework, combining... Figure 3 (b) The XRD diffraction pattern of S-1 confirms the successful synthesis of a one-dimensional rod-shaped nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material.

[0045] Example 2:

[0046] The preparation method of the one-dimensional rod-shaped nitrogen-doped porous carbon matrix coated CoNi alloy nanoparticle composite material in this embodiment includes the following steps:

[0047] (1) Dissolve 0.396 g of 2,5-dihydroxyterephthalic acid and 180 mg of sodium hydroxide in 90 ml of deionized water to form solution A. Dissolve 0.476 g of cobalt chloride hexahydrate and 0.475 g of nickel chloride hexahydrate 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 60 min. After centrifugation, washing, and drying, obtain Co. 0.5 Ni 0.5 -MOF-74 nanorod powder.

[0048] (2) Dissolve 1.5g of 2-methylimidazole in 20ml of methanol, then add 102.5mg of Co 0.5 Ni 0.5MOF-74 nanorod powder was dispersed evenly to obtain solution C; 0.2 g of zinc nitrate hexahydrate was dissolved in 5 ml of methanol, denoted as solution D; solution D was slowly added to solution C, and the reaction was magnetically stirred. The product was centrifuged, washed, and dried to obtain...

[0049] Co 0.5 Ni 0.5 -MOF-74@ZIF-8 nanorod powder.

[0050] (3) Co 0.5 Ni 0.5 -MOF-74@ZIF-8 nanorod powder was annealed under argon protection at 700℃ for 2 hours with a heating rate of 2℃ / min to obtain a one-dimensional rod-shaped nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material, labeled as S-2.

[0051] Figure 2 The images shown are (a) FESEM image of the precursor, (b) FESEM image, (c) nitrogen elemental distribution map, and (b) TEM image in this embodiment. Figure 1 (a) and Figure 3 (a) The XRD diffraction pattern of the precursor shows that a layer of ZIF-8 particles was successfully coated on the precursor. Figure 2 As shown in (bd), after pyrolysis, nitrogen has been successfully introduced into the carbon matrix. The magnetic CoNi alloy nanoparticles are uniformly and diffusely distributed within the porous carbon framework, combining... Figure 3 The XRD diffraction pattern of S-2 in (b) confirms the successful synthesis of a one-dimensional rod-shaped nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material.

[0052] Example 3: Wave Absorption Performance Test

[0053] One-dimensional rod-shaped nitrogen-doped porous carbon matrix coated with CoNi alloy nanoparticles and paraffin wax were uniformly mixed at mass ratios of 2:8 and 3:8, respectively. The mixture was then pressed into coaxial ring samples with an inner diameter of 3.04 mm and an outer diameter of 7.00 mm. Electromagnetic parameters in the centimeter wave (2-18 GHz) band were tested using the coaxial method. The ring was then pressed into a block sample with a length of 7.2 mm and a width of 3.6 mm. Electromagnetic parameters in the millimeter wave (26.5-40 GHz) band were tested using the waveguide method. The performance parameters of reflection loss were then obtained through calculation and simulation.

[0054] Figure 4 , Figure 5The mass ratios of the one-dimensional rod-shaped nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material obtained in Example 1 to paraffin wax were 2:8 and 3:7, respectively. Subsequently, three-dimensional reflection loss diagrams were obtained in the centimeter wave (2-18GHz) (a) and millimeter wave (26.5-40GHz) (b) frequency bands. Figure 6 , Figure 7 The figures for Example 2 show the one-dimensional rod-shaped nitrogen-doped porous carbon matrix-coated CoNi nanoparticle composite material with paraffin wax at mass ratios of 2:8 and 3:7, respectively. Three-dimensional reflection loss diagrams were then obtained in the centimeter wave (2-18 GHz) (a) and millimeter wave (26.5-40 GHz) (b) frequency bands. It can be seen that the obtained nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material exhibits good electromagnetic wave absorption performance in both the centimeter wave (2-18 GHz) and millimeter wave (26.5-40 GHz) frequency bands. The material's excellent electromagnetic wave absorption performance is mainly attributed to the following: the one-dimensional rod-shaped nitrogen-doped porous carbon matrix-coated CoNi alloy nanoparticle composite material possesses a one-dimensional rod-shaped nitrogen-doped porous carbon framework, which can leverage the advantages of heteroatom doping in carbon materials to improve overall dielectric loss. Simultaneously, its porous structure can accelerate electromagnetic wave attenuation by increasing the number of reflections of electromagnetic waves in the channel and the contact probability between the absorber and the electromagnetic wave. Nitrogen doping on the surface of the porous carbon framework improves the material's impedance matching performance, and the diffusely distributed magnetic CoNi alloy nanoparticles provide magnetic loss derived from magnetic resonance. Furthermore, nitrogen doping introduces abundant heterogeneous interfaces, improving the overall material's interfacial polarization and dipole polarization losses, thus enhancing electromagnetic wave absorption performance in both centimeter-wave and millimeter-wave bands.

[0055] 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 MOF-derived one-dimensional rod-shaped nitrogen-doped porous carbon matrix coated with CoNi nanoparticles, characterized in that... Includes the following steps: (1) 2,5-dihydroxyterephthalic acid and sodium hydroxide were added to deionized water to obtain solution A. Solution A was placed in an oil bath and heated and magnetically stirred. The concentration of 2,5-dihydroxyterephthalic acid in solution A was 10-50 mmol / L, the concentration of sodium hydroxide was 10-50 mmol / L, and the volume of solution A was 90 mL. (2) Cobalt chloride hexahydrate and nickel chloride hexahydrate were added to deionized water to obtain solution B; the concentration of cobalt chloride hexahydrate in solution B was 2-40 mmol / L, the concentration of nickel chloride hexahydrate was 2-40 mmol / L, and the volume of solution B was 10 mL. (3) Slowly add solution B to solution A, place it in an oil bath and heat and stir to react. The heating temperature is 80-100 ℃ and the reaction time is 30-60 min. Centrifuge, wash and dry the product to obtain Co / Ni-MOF-74 nanorod powder. (4) Dissolve 2-methylimidazole in methanol, then add Co / Ni-MOF-74 nanorod powder and disperse it evenly, and denot it as solution C; the concentration of 2-methylimidazole in solution C is 400-800 mmol / L, the concentration of Co / Ni-MOF-74 nanorod powder is 8-16 mmol / L, and the volume of solution A is 20 mL; (5) Dissolve zinc nitrate hexahydrate in methanol and denote it as solution D; the concentration of zinc nitrate hexahydrate in solution D is 20-40 mmol / L and the volume of solution D is 5 mL; (6) Slowly add solution D to solution C, stir magnetically for 15-30 min, centrifuge, wash and dry the product to obtain Co / Ni-MOF-74@ZIF-8 nanorod powder; (7) The obtained Co / Ni-MOF-74@ZIF-8 nanorod powder was annealed under argon protection at a temperature of 600-800 ℃, a holding time of 2-4 h, and a heating rate of 2-5 ℃ / min to obtain a nitrogen-doped porous carbon matrix coated CoNi alloy nanoparticle composite material.

2. The preparation method according to claim 1, characterized in that: In step (1), the heating temperature is 80-100 ℃.

3. The application of the one-dimensional rod-shaped nitrogen-doped porous carbon matrix-coated CoNi nanoparticle composite material prepared by any one of the preparation methods in claims 1-2, characterized in that: The composite material is used as an electromagnetic wave absorbing material for electromagnetic wave absorption in the 2 GHz-18 GHz centimeter wave or 26.5 GHz-40 GHz millimeter wave frequency bands.

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