Magnetic carbon-based nanomicrospheres based on cuttle ink, method for preparing the same, and electromagnetic wave absorbing element

Abstract

The application discloses a kind of magnetic carbon-based nanometer microspheres based on cuttle ink, its preparation method and electromagnetic wave absorbing element, belong to electromagnetic wave absorbing material technical field.The preparation method includes the following steps: cuttle ink is washed by multiple centrifugal washing with deionized water to obtain melanin nanometer microspheres;After being mixed with 2-methyl imidazole solution, soluble metal salt solution is added to react at room temperature, and melanin nanometer microspheres loaded with metal organic framework are obtained;Melanin nanometer microspheres loaded with metal organic framework are pyrolyzed under inert atmosphere, so that metal organic framework is pyrolyzed to form metal nanoparticles, and magnetic carbon-based nanometer microspheres are prepared.To solve the problem that the performance of the existing wave-absorbing material is poor, the preparation process is complicated, the environmental friendliness is poor and the cost is high, and to fill the technical gap of efficient utilization of biomass carbon source in the field of magnetic-dielectric composite wave-absorbing material.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic wave absorbing materials technology, and in particular to a magnetic carbon-based nanosphere based on squid ink, its preparation method, and an electromagnetic wave absorbing element. Background Technology

[0002] The development of next-generation communication technologies has spurred the creation of numerous portable, high-performance electronic devices. While greatly facilitating people's lives, these devices have also brought increasingly serious problems of electromagnetic radiation and electromagnetic pollution, leading the industry to place higher performance demands on absorbing materials. Traditional absorbing materials, characterized by their single composition, difficulty in processing, and large size, are no longer sufficient to meet the needs of practical applications and market development.

[0003] Carbon-based materials, such as graphene and carbon nanotubes, are widely used in electromagnetic wave absorption and electromagnetic interference shielding due to their advantages such as low density, high specific surface area, and high dielectric loss characteristics. However, although single carbon-based materials have excellent dielectric properties, their weak magnetic loss capability and poor impedance matching characteristics make it difficult to achieve efficient broadband absorption of electromagnetic waves, thus limiting their practical applications.

[0004] To address the aforementioned issues, combining carbon-based materials with magnetic components to construct a "magnetic-dielectric" synergistic loss system can effectively enhance the electromagnetic wave attenuation capability of the material. Currently, most composite materials are prepared using chemical raw materials, which suffers from high costs, complex processes, and insufficient environmental friendliness. Biomass carbon sources are widely available and environmentally friendly, making it an important development direction for novel microwave absorbing materials. Summary of the Invention

[0005] To overcome the above shortcomings, the present invention aims to provide a magnetic carbon-based nanosphere based on squid ink, its preparation method and electromagnetic wave absorbing element, so as to solve the problems of insufficient performance, complicated preparation process, poor environmental friendliness and high cost of existing wave absorbing materials, and fill the technical gap in the efficient utilization of biomass carbon source in the field of magnetic-dielectric composite wave absorbing materials.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows: This invention provides a method for preparing magnetic carbon-based nanospheres based on squid ink, comprising the following steps: Step 1: The squid ink is centrifuged and washed to obtain melanin nanospheres; Step 2: Mix the 2-methylimidazole solution with the melanin nanospheres to obtain a mixture; Step 3: Add a soluble metal salt solution to the mixture, and react at room temperature to obtain melanin nanospheres loaded with metal-organic frameworks; Step 4: The melanin nanospheres loaded with metal-organic frameworks are pyrolyzed under an inert atmosphere to obtain magnetic carbon-based nanospheres.

[0007] By adopting the above technical solution, the beneficial technical effects obtained by the present invention are as follows: This invention provides a simple, efficient, and customizable method for preparing magnetic carbon-based nanospheres using squid ink, a natural biomass, as the carbon source. The process is environmentally friendly, uses readily available raw materials, and offers strong controllability. An efficient "magnetic-dielectric" synergistic loss system is successfully constructed by in-situ loading magnetic nanoparticles. The resulting magnetic carbon-based nanospheres possess excellent impedance matching characteristics, abundant heterogeneous interfaces, and a complete conductive network. They can achieve efficient attenuation of electromagnetic waves through multiple loss mechanisms, achieving high absorption intensity and broadband absorption performance under low filler content and thin thickness conditions, meeting the core requirements of "lightweight, thin, wide, and strong" for microwave absorbing materials. Furthermore, the magnetic properties and graphitization degree of this material are controllable, and conductive and magnetic losses synergistically enhance each other. It can be combined with paraffin wax to prepare practical electromagnetic wave absorbing elements, showing broad application prospects in electromagnetic wave absorption, electromagnetic shielding, and stealth coatings. This invention also provides a novel technical solution for the development and application of biomass carbon-based microwave absorbing materials, promoting the greening and high-performance development of the electromagnetic wave absorbing materials field. Attached Figure Description

[0008] Figure 1 This is a scanning electron microscope image of the multifunctional magnetic carbon-based nanosphere material based on squid ink obtained in Example 1 of this invention; Figure 2 This is a scanning electron microscope image of the multifunctional magnetic carbon-based nanosphere material based on squid ink obtained in Example 2 of this invention; Figure 3 This is a scanning electron microscope image of the multifunctional magnetic carbon-based nanosphere material based on squid ink obtained in Example 3 of the present invention; Figure 4 The XRD patterns of the magnetic carbon-based nanospheres prepared in Examples 1, 2, and 3 are shown below. Figure 5 The Raman spectra of the magnetic carbon-based nanospheres prepared in Examples 1, 2, and 3 are shown. Detailed Implementation

[0009] The present invention is illustrated by the following examples.

[0010] The squid ink used in this invention was purchased from online commercial channels, and the raw material source was Chinese squid. The melanin nanospheres obtained by subsequent centrifugal washing of the squid ink had a particle size distribution of 138.39±21.85 nm. The melanin content was based on the inherent content range of conventional Chinese squid ink in the field as the quality control basis, without any additional direct detection data.

[0011] Example 1

[0012] Step 1: Centrifuge the squid ink at 500 rpm for 10 min to collect the supernatant. Then wash the supernatant with deionized water and centrifuge at 10000 rpm for 10 min to collect the precipitate. Wash the precipitate with deionized water and centrifuge ten times to obtain melanin nanosphere precipitate. Step 2: Dissolve 1.968 g of 2-methylimidazole in 150 ml of methanol, and then add 0.40 g of melanin nanospheres to the 2-methylimidazole solution to obtain a 2-methylimidazole-melanin nanosphere mixture. Step 3: Dissolve 1.755 g Co(NO3)2·6H2O in 150 ml methanol, then quickly mix the 2-methylimidazole-melanin nanosphere mixture with the Co(NO3)2 solution and react at room temperature for 3 h; Step 4: Centrifuge the above mixed solution at 5000 rpm for 10 min to collect the precipitate, wash it 4 times with methanol and ethanol alternately, and then vacuum dry it at 60℃ for 12 h to obtain melanin nanospheres loaded with a rhombic dodecahedral ZIF-67 cobalt-based metal-organic framework. Step 5: Place an appropriate amount of melanin nanospheres loaded with ZIF-67 cobalt-based metal-organic framework with rhombic dodecahedral structure into a horizontal tube furnace. Under N2 protection, heat the tube furnace to 300℃ at a rate of 10℃ / min and hold for 2 hours. Then heat to 700℃ at a rate of 5℃ / min and hold for 2 hours. After cooling to room temperature, collect the product C@Co magnetic carbon nanospheres (i.e., cobalt-loaded magnetic carbon nanospheres). Step 6: Mix 20 wt.% of the obtained sample with molten paraffin to prepare a composite material for use in the field of electromagnetic wave absorption.

[0013] 20 wt.% of the powdered product was uniformly mixed with molten paraffin and pressed into concentric rings. The electromagnetic parameters of the rings in the frequency range of 2-18 GHz were tested using an Agilent PNA-N5244A vector network analyzer, and the absorption performance was calculated accordingly.

[0014] The minimum reflection loss of C@Co was measured to be -54.38 dB (2.1 mm), and the effective absorption bandwidth was 5.96 GHz (1.95 mm).

[0015] Figure 1The image shows a scanning electron microscope image of the multifunctional magnetic carbon-based nanosphere material based on squid ink obtained in Example 1 of this invention. It shows the relatively complete morphology of the carbon nanospheres and the abundant Co nanoparticles anchored on the surface of the carbon nanospheres by ZIF-67 pyrolysis.

[0016] Example 2

[0017] Step 1: Centrifuge the squid ink at 500 rpm for 10 min to collect the supernatant. Then wash the supernatant with deionized water and centrifuge at 10000 rpm for 10 min to collect the precipitate. Wash the precipitate with deionized water and centrifuge ten times to obtain melanin nanosphere precipitate. Step 2: Dissolve 1.968 g of 2-methylimidazole in 150 ml of methanol, and then add 0.40 g of melanin nanospheres to the 2-methylimidazole solution to obtain a 2-methylimidazole-melanin nanosphere mixture. Step 3: Dissolve 1.755 g Co(NO3)2·6H2O in 150 ml methanol, then quickly mix the 2-methylimidazole-melanin nanosphere mixture with the Co(NO3)2 solution and react at room temperature for 3 h; Step 4: Centrifuge the above mixed solution at 5000 rpm for 10 min to collect the precipitate, wash it 4 times with methanol and ethanol alternately, and then vacuum dry it at 40℃ for 12 h to obtain melanin nanospheres loaded with a rhombic dodecahedral ZIF-67 cobalt-based metal-organic framework. Step 5: Place an appropriate amount of melanin nanospheres loaded with ZIF-67 cobalt-based metal-organic framework with rhombic dodecahedral structure into a horizontal tube furnace. Under N2 protection, heat the tube furnace to 300℃ at a rate of 10℃ / min and hold for 2 hours. Then heat it to 800℃ at a rate of 5℃ / min and hold for 2 hours. After cooling to room temperature, collect the product C@Co magnetic carbon-based nanospheres. Step 6: Mix 20 wt.% of the obtained sample with molten paraffin to prepare a composite material for use in the field of electromagnetic wave absorption.

[0018] 20 wt.% of the powdered product was uniformly mixed with molten paraffin and pressed into concentric rings. The electromagnetic parameters of the rings in the frequency range of 2-18 GHz were tested using an Agilent PNA-N5244A vector network analyzer, and the absorption performance was calculated accordingly.

[0019] The minimum reflection loss of C@Co was measured to be -20.67 dB (2.5 mm), and the effective absorption bandwidth was 4.72 GHz (1.5 mm).

[0020] Figure 2The image shows a scanning electron microscope image of the multifunctional magnetic carbon-based nanosphere material based on squid ink obtained in Example 2 of this invention. It shows the relatively complete morphology of the carbon nanospheres and the abundant Co nanoparticles anchored on the surface of the carbon nanospheres by ZIF-67 pyrolysis. Example

[0021] Step 1: Centrifuge the squid ink at 500 rpm for 10 min to collect the supernatant. Then wash the supernatant with deionized water and centrifuge at 10000 rpm for 10 min to collect the precipitate. Wash the precipitate with deionized water and centrifuge 10 times to obtain melanin nanosphere precipitate. Step 2: Dissolve 1.968 g of 2-methylimidazole in 150 ml of methanol, and then add 0.40 g of melanin nanospheres to the 2-methylimidazole solution to obtain a 2-methylimidazole-melanin nanosphere mixture. Step 3: Dissolve 1.755 g Co(NO3)2·6H2O in 150 ml methanol, then quickly mix the 2-methylimidazole-melanin nanosphere mixture with the Co(NO3)2 solution and react at room temperature for 3 h; Step 4: Centrifuge the above mixed solution at 5000 rpm for 10 min to collect the precipitate, wash it 4 times with methanol and ethanol alternately, and then dry it under vacuum at 40℃ for 12 h to obtain melanin nanospheres loaded with a rhombic dodecahedral ZIF-67 cobalt-based metal-organic framework. Step 5: Place an appropriate amount of melanin nanospheres loaded with ZIF-67 cobalt-based metal-organic framework with rhombic dodecahedral structure into a horizontal tube furnace. Under N2 protection, heat the tube furnace to 300℃ at a rate of 10℃ / min and hold for 2 hours. Then heat it to 900℃ at a rate of 5℃ / min and hold for 2 hours. After cooling to room temperature, collect the product C@Co magnetic carbon-based nanospheres. Step 6: Mix 20 wt.% of the obtained sample with molten paraffin to prepare a composite material for use in the field of electromagnetic wave absorption.

[0022] 20 wt.% of the powdered product was uniformly mixed with molten paraffin and pressed into concentric rings. The electromagnetic parameters of the rings in the frequency range of 2-18 GHz were tested using an Agilent PNA-N5244A vector network analyzer, and the absorption performance was calculated accordingly.

[0023] The minimum reflection loss of C@Co was measured to be -30.16 dB (2.2 mm), and the effective absorption bandwidth was 4.96 GHz (1.5 mm).

[0024] Figure 3The image shown is a scanning electron microscope image of the multifunctional magnetic carbon-based nanosphere material based on squid ink obtained in Example 3 of this invention. It shows a relatively complete carbon nanosphere morphology. Due to the further increase in pyrolysis temperature, a denser Co nanoparticle shell is formed on the surface of the carbon nanospheres.

[0025] Figure 4 The XRD patterns of the multifunctional magnetic carbon-based nanospheres based on squid ink prepared in Examples 1, 2, and 3 are shown. All samples exhibit distinct characteristic diffraction peaks near 2θ≈20°, corresponding to the (002) crystal plane of graphitic carbon, indicating that the samples after high-temperature treatment possess a certain graphite structure. In Examples 1 and 2, diffraction peaks of Co (PDF#15-0806), Co3O4 (PDF#42-1467), and CoO (PDF#48-1719) appear, verifying the successful synthesis of the materials. In Example 3, only diffraction peaks of Co (PDF#15-0806) and CoO (PDF#48-1719) are observed, indicating that Co3O4 further pyrolyzes into Co and CoO at higher carbonization temperatures.

[0026] Figure 5 The images show the Raman spectra of the multifunctional magnetic carbon-based nanospheres based on squid ink prepared in Examples 1, 2, and 3. All samples were analyzed at 1350 cm⁻¹. -1 Nearby and 1580cm -1 Two distinct peaks are observed nearby, corresponding to the D peak representing graphite defects and the sp peak representing graphite carbon, respectively. 2 The G peak of bond stretching vibration. The ratio of their intensities (R = ID / IG) is often used to characterize the degree of graphitization of a sample; a lower R value indicates a higher degree of graphitization. The R value for pure melanin nanospheres is 1.16. Figure 5 As can be seen, the R values ​​of all embodiments are smaller than those of pure melanin nanospheres, and Example 3 < Example 2 < Example 1. This is closely related to the catalytic ability of metals at higher carbonization temperatures. A higher degree of graphitization can improve the electrical conductivity of the material, thereby enhancing the conductivity loss of electromagnetic waves.

[0027] Table 1 shows the hysteresis loop and coercivity information of the multifunctional magnetic carbon-based nanospheres based on squid ink prepared in Examples 1, 2, and 3 of this invention. Due to the uniform anchoring of the magnetic nanoparticles on the surface of the carbon nanospheres, all examples exhibit good ferromagnetic activity under external magnetic field excitation. All examples show S-shaped curves with low coercivity, indicating their soft magnetic and ferromagnetic behavior. As shown in Table 1, the higher saturation magnetization (… M s This is beneficial for breaking the Snoek limit, obtaining higher complex permeability, and thus enhancing magnetic loss. Larger coercivity (H c It can enhance magnetic anisotropy, shift the natural resonance peak to higher frequencies, optimize magnetic loss in the GHz band, and thus more easily achieve excellent electromagnetic wave absorption performance.

[0028] Table 1

[0029] Table 2 shows the electromagnetic wave absorption performance of the multifunctional magnetic carbon-based nanospheres based on squid ink prepared in Examples 1, 2, and 3 of this invention, demonstrating their lowest reflection loss (RL). min The table shows the effective absorption bandwidth (EAB), corresponding thickness (t), and loading. As can be seen from Table 2, within the test range of 2-18 GHz, all embodiments achieved high absorption intensity with thin thickness and low filler content, while the effective absorption bandwidth could stably reach above 4.7 GHz, verifying its wide application value and demonstrating significant advantages in the "thin, light, wide, and strong" aspects of electromagnetic wave dissipation. This is mainly due to ideal impedance matching and the synergistic mechanism of "magnetic-dielectric" dual losses.

[0030] Table 2

[0031] The magnetic carbon-based nanospheres based on squid ink obtained in this invention meet the core technical requirements of "lightweight, thin, wide, and strong" for microwave absorbing materials. The performance in each dimension is fully demonstrated through specific quantitative data: Thinness is reflected in the ability to achieve efficient electromagnetic wave absorption even at ultra-thin thicknesses; with a thickness of 1.95 mm, the material's effective absorption bandwidth reaches 5.96 GHz, achieving efficient microwave absorption with low thickness. Wideness is reflected in the extremely wide effective absorption bandwidth; the 5.96 GHz effective absorption bandwidth can almost cover the entire Ku band (12.04 GHz-18 GHz), significantly broadening the frequency range for efficient microwave absorption. Strongness is reflected in the excellent electromagnetic wave absorption intensity; the material's minimum reflection loss reaches -54.38 dB, and its electromagnetic wave absorption efficiency is as high as 99.99%, achieving strong attenuation absorption of electromagnetic waves. Simultaneously, the material of this invention only requires a low filling amount of 20 wt.% to achieve the above-mentioned excellent performance, significantly reducing the raw material load ratio of the microwave absorbing composite material, fully reflecting the core requirement of lightness, and comprehensively meeting the practical application needs of microwave absorbing materials.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can be modified and varied in many ways. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing magnetic carbon-based nanospheres based on squid ink, characterized in that, Includes the following steps: Step 1: The squid ink is centrifuged and washed to obtain melanin nanospheres; Step 2: Mix the 2-methylimidazole solution with the melanin nanospheres to obtain a mixture; Step 3: Add a soluble metal salt solution to the mixture, and react at room temperature to obtain melanin nanospheres loaded with metal-organic frameworks; Step 4: The melanin nanospheres loaded with metal-organic frameworks are pyrolyzed under an inert atmosphere to obtain magnetic carbon-based nanospheres.

2. The preparation method according to claim 1, characterized in that, The soluble metal salt is Co(NO3)2.

3. The preparation method according to claim 1, characterized in that, The concentration of the 2-methylimidazole solution is 0.100–0.200 mol / L; the mass percentage of the melanin nanospheres is 0.3–0.5 wt.%; the Co(NO3)2 solution, after preparation, is mixed with the 2-methylimidazole-melanin nanosphere mixture in the system containing the Co... 2+ The concentration is 0.01–0.03 mol / L.

4. The preparation method according to claim 1, characterized in that, In step 3, the reaction time at room temperature is 3 hours.

5. The preparation method according to claim 1, characterized in that, The inert gas is N2.

6. The preparation method according to claim 1, characterized in that, The pyrolysis temperature is 700–900℃, and the pyrolysis time is 2 h.

7. A magnetic carbon-based nanosphere based on squid ink, characterized in that, Prepared by the preparation method according to any one of claims 1-6.

8. An electromagnetic wave absorbing element, characterized in that, The microwave absorbing composite material is formed by molding. The microwave absorbing composite material contains the magnetic carbon-based nanospheres based on squid ink as described in claim 7 and paraffin wax, and the mass fraction of the magnetic carbon-based nanospheres in the microwave absorbing composite material is 10 to 30 wt.%.

9. The electromagnetic wave absorbing element according to claim 8, characterized in that, The molding process is compression molding, and the electromagnetic wave absorbing element is in the shape of a concentric ring.

10. The electromagnetic wave absorbing element according to any one of claims 8-9, characterized in that, The magnetic carbon-based nanospheres have a mass fraction of 20 wt.%.

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