Two-dimensional silicon dioxide nanosheet loaded metal wave-absorbing material and preparation method thereof

Abstract

The application relates to the technical field of electromagnetic wave absorbing materials, in particular to a two-dimensional silicon dioxide nanosheet loaded metal wave absorbing material and a preparation method thereof. The specific preparation method comprises the following steps: stirring and mixing a silicide and a metal chloride-ethanol solution, adjusting the topological peeling process of the silicide by using the metal chloride, and obtaining a two-dimensional silicon dioxide nanosheet mixture; then, calcining at 400 DEG C to 1000 DEG C, and reducing under a reducing atmosphere at 800 DEG C to 1200 DEG C, so that the nanometer metal particles with a single domain size are uniformly dispersed on the two-dimensional silicon dioxide nanosheet to form a heterostructure, and the two-dimensional silicon dioxide nanosheet loaded metal wave absorbing material is prepared. The application solves the problems that the existing method for compounding two-dimensional materials and nanoparticles is non-in-situ, the nanoparticles are not uniformly dispersed on the two-dimensional materials, the size is uncontrollable, and the electromagnetic absorption performance is low.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic absorbing materials technology, specifically to a two-dimensional silica nanosheet-loaded metal absorbing material and its preparation method. Background Technology

[0002] Stealth technology refers to the use of special external structures or surface coatings to reduce the detectable signal characteristics of a target, thereby disabling the enemy's detection systems. Among stealth technologies, radar stealth currently receives considerable attention due to its dominant role in detection technology. Radar stealth technology primarily reduces the target's radar cross-section, making it difficult for radar detection systems to detect and track. To achieve this goal, scientists are constantly exploring various new materials and technologies to improve the stealth performance of weaponry.

[0003] In recent years, two-dimensional materials have shown great application potential in the field of electromagnetic absorbing materials due to their high specific surface area, abundant exposed atoms, and excellent mechanical, optical, and electronic properties. Among them, silica, as a widely used electromagnetic wave transmission material, possesses excellent thermal stability, corrosion resistance, and cost-effectiveness, making it an ideal choice for preparing electromagnetic absorbing materials. By combining nanoparticles with silica, the penetration of incident electromagnetic waves can be maximized to improve the electromagnetic absorption performance of the material, and the stealth performance can be enhanced by improving impedance matching.

[0004] However, in practical applications, the combination of nanoparticles and silica remains a challenging technical problem. Current methods for combining nanoparticles with silica, such as sol-gel and precipitation methods, while achieving the desired combination, often suffer from uneven particle size and poor dispersibility. This uneven dispersion significantly impacts the performance of electromagnetic absorbing materials. Specifically, the aggregation and uneven distribution of nanoparticles lead to enhanced electromagnetic wave scattering and reflection, thereby reducing the material's electromagnetic absorption efficiency. Furthermore, these methods may introduce impurities, further affecting the performance of the electromagnetic absorbing materials. Summary of the Invention

[0005] To address the problem that the current combination of nanoparticles and silica suffers from uneven particle size and poor dispersion, which severely affects the performance of electromagnetic absorbing materials, the present invention aims to provide a two-dimensional silica nanosheet-loaded metal absorbing material and its preparation method.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows.

[0007] The first aspect of this invention provides a method for preparing a two-dimensional silica nanosheet-loaded metal absorbing material, comprising the following steps:

[0008] The silicide was stirred and mixed with a metal chloride-ethanol solution. The metal chloride was used to regulate the topological exfoliation process of the silicide to obtain a mixture of two-dimensional silica nanosheets. Then, it was calcined at 400℃~1000℃ and reduced at 800℃~1200℃ in a reducing atmosphere to uniformly disperse single-domain-sized nano-metal particles on the two-dimensional silica nanosheets to form a heterostructure, thus obtaining a two-dimensional silica nanosheet-loaded metal absorbing material.

[0009] This invention mainly utilizes metal chloride salts to regulate the topological exfoliation process of silicides to form two-dimensional nanosheet materials. Simultaneously, through high-temperature reduction treatment, metal particles are grown in situ on the two-dimensional nanosheet materials, ultimately obtaining a heterogeneous structure of two-dimensional SiO2 loaded with uniformly dispersed and nano-sized particles. This solves the problem in existing methods of combining two-dimensional materials with nanoparticles, where the nanoparticles are not uniformly dispersed on the two-dimensional material, are not in situ, and have uncontrollable size, resulting in low electromagnetic absorption performance.

[0010] In this invention, the reduction temperature is 800℃~1200℃. Too high a reduction temperature will cause agglomeration or even sintering; while too low a reduction temperature will result in more impurities, making the reduction incomplete.

[0011] Preferably, the size of the nano-metal particles is 10nm to 20nm; the size of the two-dimensional silica nanosheets is 1μm to 50μm, and the thickness is 20nm to 200nm.

[0012] Preferably, the metal chloride salt is at least one selected from cobalt chloride, ferric chloride, nickel chloride, chromium chloride, and copper chloride.

[0013] This invention is based on a confinement strategy and utilizes metal chloride salts. On the one hand, it is used to regulate the intercalation and stripping process of silicides. On the other hand, through high-temperature reduction treatment and temperature regulation, metal ions are transformed into single-domain-sized nano-metal particles, which are grown in situ on two-dimensional nanosheet materials. The resulting two-dimensional SiO2 load has a uniform dispersion and a heterogeneous structure of nano-sized particles, which can effectively control electromagnetic parameters and obtain excellent electromagnetic absorption performance.

[0014] Metal nanoparticles, such as Fe, Co, Ni, and Cu, possess excellent electrical conductivity and nanoscale effect, which can provide efficient electrical and magnetic losses.

[0015] Preferably, the silicide is at least one selected from calcium silicide, magnesium silicide, iron silicide, copper silicide, and chromium silicide.

[0016] In this invention, silicides are mainly used as raw materials for forming two-dimensional silica nanosheets. The topological exfoliation process of silicides is adjusted by metal chloride salts to form two-dimensional silica nanosheets. Due to the significant advantages of two-dimensional silica nanosheets, such as fully exposed active sites, high specific surface area, a large number of surface exposed atoms, and excellent mechanical and electronic properties, electromagnetic parameters can be effectively controlled and excellent electromagnetic absorption performance can be obtained.

[0017] Preferably, the mass ratio of silicide to metal chloride is 1:0.1 to 3.0.

[0018] In this invention, as the content of metal chloride salt increases, the number of doped metal particles increases, conductivity improves, and dielectric constant increases. When the content of metal chloride salt is too low, the doping amount is too small, and the effect on conductivity and dielectric parameters is minimal. When the content of metal chloride salt is too high, it is easy to cause agglomeration and excessive conductivity.

[0019] Preferably, the reducing atmosphere is a reducing gas or a mixture of a reducing gas and a protective gas; the reducing gas is hydrogen or carbon monoxide; and the protective gas is nitrogen or argon.

[0020] Preferably, in the metal chloride-ethanol solution, the ratio of metal chloride to ethanol is 0.25g to 6g: 100mL.

[0021] Preferably, the mixing temperature is 50℃~90℃, and the mixing time is 2h~10h.

[0022] In this invention, as the temperature of stirring and mixing increases, the dissolution rate accelerates, and the stirring time can be shortened accordingly. When the temperature exceeds 90°C, the reaction is too uneven. When the temperature exceeds 100°C, it will boil directly. When the temperature is too low, the dissolution is too slow, and there will be precipitates.

[0023] Preferably, after stirring and mixing, the mixture is further washed with ethanol and water, centrifuged, the centrifuged precipitate is collected and dried to obtain a mixture of two-dimensional silica nanosheets.

[0024] Preferably, the number of washing cycles is 1 to 5; the centrifugation speed is 5000 rpm to 10000 rpm; and the centrifugation time is 5 min to 30 min.

[0025] Preferably, the drying temperature is 50℃~100℃ and the drying time is 12h~24h.

[0026] The second aspect of the present invention provides a two-dimensional silica nanosheet-loaded metal absorbing material prepared by the preparation method described in the first aspect.

[0027] The beneficial effects of this invention are:

[0028] 1. This invention mainly utilizes metal chloride salts to regulate the topological exfoliation process of silicides to form two-dimensional nanosheet materials. Simultaneously, through high-temperature reduction treatment, metal particles are grown in situ on the two-dimensional nanosheet materials, ultimately obtaining a heterogeneous structure with uniform dispersion and nano-sized particles supported by two-dimensional SiO2. This solves the problem in existing methods where the nanoparticles are not uniformly dispersed on the silica, resulting in low electromagnetic absorption performance.

[0029] 2. Benefiting from the synergistic effect of magneto-dielectric properties and by adjusting the particle size of the nano-metal particles at different temperatures, the absorption intensity and absorption bandwidth can be effectively improved. The two-dimensional silica nanosheet-loaded metal absorbing material prepared in this invention exhibits excellent electromagnetic properties, with a maximum absorption intensity of -51.6 dB and an effective absorption bandwidth of 4.6 GHz. Attached Figure Description

[0030] Figure 1 This is a morphology diagram of the two-dimensional silica nanosheet-supported cobalt nanocomposite material prepared in Example 1.

[0031] Figure 2 This is a morphology diagram of the two-dimensional silica nanosheet-supported cobalt nanocomposite material prepared in Example 2.

[0032] Figure 3 These are X-ray diffraction patterns of the two-dimensional silica nanosheet-supported cobalt nanocomposites prepared in Examples 2 to 4.

[0033] Figure 4 This is a TEM image of the two-dimensional silica nanosheet-supported cobalt nanocomposite material prepared in Example 1.

[0034] Figure 5 The electromagnetic absorption performance of cobalt nanocomposites supported on two-dimensional silica nanosheets of different thicknesses is shown in the figure. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Silica, as a widely used electromagnetic wave transmission material, possesses excellent thermal stability, corrosion resistance, and cost-effectiveness. It can maximize the penetration of incident electromagnetic waves and improve the stealth performance of materials by enhancing impedance matching. However, how to combine nanoparticles with silica and achieve uniform dispersion of nanoparticles on silica to improve the electromagnetic absorption performance of materials is an important direction in current stealth material research.

[0038] Spatial confinement strategies are an efficient and promising approach in designing high-efficiency electromagnetic absorbing materials, laying the foundation for the development of advanced electromagnetic absorbing materials. By controlling the growth of nanoparticles within a confined space, it is possible to rationally adjust the particle size and optimize its configuration at the atomic level, thereby endowing the material with physicochemical properties, including electron transfer capabilities and atomic configuration, within a limited space. These properties differ significantly from those in bulk materials, providing new insights for developing high-performance electromagnetic absorbing materials.

[0039] This invention proposes a novel confinement strategy for developing two-dimensional nanoscale metal / silica heterostructures, in which the in-situ grown metal particles possess nanoscale dimensions, facilitating enhanced electromagnetic loss through strong surface anisotropy. This advanced absorbing material, exhibiting significant electromagnetic absorption capabilities and a wide bandwidth, provides a general strategy for the synthesis of other two-dimensional composite materials with controllable structures.

[0040] A method for preparing a two-dimensional silica nanosheet-supported cobalt nanocomposite material includes the following steps:

[0041] Step 1: Dissolve the metal chloride salt in ethanol and stir magnetically for a period of time to form a metal chloride-ethanol solution. The metal chloride salt is at least one of cobalt chloride, ferric chloride, nickel chloride, chromium chloride, and copper chloride. The ratio of metal chloride salt to ethanol is 0.25g to 6g:100mL, and the stirring time is 0.5h to 2h.

[0042] Step 2: Add the silicide raw material to the above solution, stir thoroughly at a certain temperature, wash several times with ethanol and ultrapure water, centrifuge, and collect the resulting mixture. The silicide is at least one of calcium silicide, magnesium silicide, iron silicide, copper silicide, and chromium silicide. The mass ratio of silicide to metal chloride salt is 1:0.1–3. The reaction temperature is 50℃–90℃, the stirring time is 2h–10h, the centrifugation time is 5min–30min, and the rotation speed is 5000 rpm–10000 rpm.

[0043] Step 3: The product obtained in Step 2 is dried under vacuum to obtain two-dimensional silicon nanosheets. The drying temperature is 50℃~100℃, and the drying time is 12h~24h.

[0044] Step 4: The dried powder obtained in Step 3 is calcined in air at different temperatures, and finally reduced under a high-temperature reducing atmosphere to obtain the final product of two-dimensional silica nanosheets supporting metal particles. The calcination temperature is 400℃~1000℃, and the calcination time is 2h~8h. The high-temperature reduction temperature is 800℃~1200℃, and the reduction time is 1h~5h. The reducing gas is any one of high-purity H2, CO, N2 / H2, Ar / H2, and CO / N2.

[0045] The technical solution of the present invention will be further described below through specific embodiments.

[0046] In the following embodiments, unless otherwise specified, the methods described are conventional methods; and unless otherwise specified, the reagents and materials described are commercially available. Example

[0047] A method for preparing a two-dimensional silica nanosheet-supported cobalt nanocomposite material includes the following steps:

[0048] Step 1: Dissolve 0.5g of CoCl2 in 50mL of ethanol and stir magnetically for 0.5 hours to obtain an ethanol solution of CoCl2.

[0049] Step 2: Add 1.2g CaSi2 to an ethanol solution of CoCl2, stir thoroughly at 70℃ for 5 hours, wash three times with ethanol and ultrapure water respectively, centrifuge for 5 minutes at 8000 rpm, collect the precipitate, and dry it under vacuum at 80℃ for 12 hours to obtain two-dimensional silicon composite nanosheet powder.

[0050] Step 3: The two-dimensional silicon composite nanosheet powder obtained in S2 is calcined in air at 600℃ for 2 hours, and then reduced at 800℃ in an N2 / H2 atmosphere for 3 hours, with a hydrogen flow rate of 60 mL / min and a nitrogen flow rate of 240 mL / min, to obtain a two-dimensional silicon dioxide nanosheet-supported cobalt nanocomposite material. Example

[0051] A method for preparing a two-dimensional silica nanosheet-supported cobalt nanocomposite material differs from Example 1 in that the calcination temperature is 950℃. The specific method includes the following steps:

[0052] Step 1: Dissolve 0.5g of CoCl2 in 50mL of ethanol and stir magnetically for 0.5 hours to obtain an ethanol solution of CoCl2.

[0053] Step 2: Add 1.2g CaSi2 to an ethanol solution of CoCl2, stir thoroughly at 70℃ for 5 hours, wash three times with ethanol and ultrapure water respectively, centrifuge for 5 minutes at 8000 rpm, collect the precipitate, and dry it under vacuum at 80℃ for 12 hours to obtain two-dimensional silicon composite nanosheet powder.

[0054] Step 3: The two-dimensional silicon composite nanosheet powder obtained in S2 is calcined in air at 950°C for 2 hours, and then reduced at 800°C in an N2 / H2 atmosphere for 3 hours, with a hydrogen flow rate of 60 mL / min and a nitrogen flow rate of 240 mL / min, to obtain a two-dimensional silicon dioxide nanosheet-supported cobalt nanocomposite material. Example

[0055] A method for preparing a two-dimensional silica nanosheet-supported cobalt nanocomposite material differs from Example 1 in that the calcination temperature is 800℃. The specific method includes the following steps:

[0056] Step 1: Dissolve 0.5g of CoCl2 in 50mL of ethanol and stir magnetically for 0.5 hours to obtain an ethanol solution of CoCl2.

[0057] Step 2: Add 1.2g CaSi2 to an ethanol solution of CoCl2, stir thoroughly at 70℃ for 5 hours, wash three times with ethanol and ultrapure water respectively, centrifuge for 5 minutes at 8000 rpm, collect the precipitate, and dry it under vacuum at 80℃ for 12 hours to obtain two-dimensional silicon composite nanosheet powder.

[0058] Step 3: The two-dimensional silicon composite nanosheet powder obtained in S2 is calcined in air at 800℃ for 2 hours, and then reduced at 800℃ in an N2 / H2 atmosphere for 3 hours, with a hydrogen flow rate of 60 mL / min and a nitrogen flow rate of 240 mL / min, to obtain a two-dimensional silicon dioxide nanosheet-supported cobalt nanocomposite material. Example

[0059] A method for preparing a two-dimensional silica nanosheet-supported cobalt nanocomposite material differs from Example 1 in that the calcination temperature is 400℃. The specific method includes the following steps:

[0060] Step 1: Dissolve 0.5g of CoCl2 in 50mL of ethanol and stir magnetically for 0.5 hours to obtain an ethanol solution of CoCl2.

[0061] Step 2: Add 1.2g CaSi2 to an ethanol solution of CoCl2, stir thoroughly at 70℃ for 5 hours, wash three times with ethanol and ultrapure water respectively, centrifuge for 5 minutes at 8000 rpm, collect the precipitate, and dry it under vacuum at 80℃ for 12 hours to obtain two-dimensional silicon composite nanosheet powder.

[0062] Step 3: The two-dimensional silicon composite nanosheet powder obtained in S2 is calcined in air at 400°C for 2 hours, and then reduced at 800°C in an N2 / H2 atmosphere for 3 hours, with a hydrogen flow rate of 60 mL / min and a nitrogen flow rate of 240 mL / min, to obtain a two-dimensional silicon dioxide nanosheet-supported cobalt nanocomposite material. Example

[0063] A method for preparing a two-dimensional silica nanosheet-supported cobalt nanocomposite material differs from Example 1 in that the calcination temperature is 1000℃. The specific method includes the following steps:

[0064] Step 1: Dissolve 0.5g of CoCl2 in 50mL of ethanol and stir magnetically for 0.5 hours to obtain an ethanol solution of CoCl2.

[0065] Step 2: Add 1.2g CaSi2 to an ethanol solution of CoCl2, stir thoroughly at 70℃ for 5 hours, wash three times with ethanol and ultrapure water respectively, centrifuge for 5 minutes at 8000 rpm, collect the precipitate, and dry it under vacuum at 80℃ for 12 hours to obtain two-dimensional silicon composite nanosheet powder.

[0066] Step 3: The two-dimensional silicon composite nanosheet powder obtained in S2 is calcined in air at 1000℃ for 2 hours, and then reduced at 800℃ in an N2 / H2 atmosphere for 3 hours, with a hydrogen flow rate of 60 mL / min and a nitrogen flow rate of 240 mL / min, to obtain a two-dimensional silicon dioxide nanosheet-supported cobalt nanocomposite material. Example

[0067] A method for preparing a two-dimensional silica nanosheet-supported cobalt nanocomposite material includes the following steps:

[0068] Step 1: Dissolve 0.12g of CoCl2 in 50mL of ethanol and stir magnetically for 0.5 hours to obtain an ethanol solution of CoCl2.

[0069] Step 2: Add 1.2g CaSi2 to an ethanol solution of CoCl2, making the mass ratio of silicide to metal chloride salt 1:0.1. Stir thoroughly at 50℃ for 10 hours, wash three times with ethanol and ultrapure water respectively, centrifuge for 30 minutes at 5000 rpm, collect the precipitate, and dry it under vacuum at 100℃ for 12 hours to obtain two-dimensional silicon composite nanosheet powder.

[0070] Step 3: The two-dimensional silicon composite nanosheet powder obtained in S2 is calcined in air at 600℃ for 2 hours, and then reduced at 1200℃ in an N2 / H2 atmosphere for 1 hour, with a hydrogen flow rate of 60 mL / min and a nitrogen flow rate of 240 mL / min, to obtain a two-dimensional silicon dioxide nanosheet-supported cobalt nanocomposite material. Example

[0071] A method for preparing a two-dimensional silica nanosheet-supported cobalt nanocomposite material includes the following steps:

[0072] Step 1: Dissolve 3.6g of CoCl2 in 50mL of ethanol and stir magnetically for 0.5 hours to obtain an ethanol solution of CoCl2.

[0073] Step 2: Add 1.2g CaSi2 to an ethanol solution of CoCl2, making the mass ratio of silicide to metal chloride salt 1:3. Stir thoroughly at 90℃ for 2 hours, wash three times with ethanol and ultrapure water respectively, centrifuge for 20 minutes at 10000 rpm, collect the precipitate, and dry it under vacuum at 50℃ for 24 hours to obtain two-dimensional silicon composite nanosheet powder.

[0074] Step 3: The two-dimensional silicon composite nanosheet powder obtained in S2 is calcined in air at 800℃ for 2 hours, and then reduced at 800℃ in an N2 / H2 atmosphere for 5 hours, with a hydrogen flow rate of 60 mL / min and a nitrogen flow rate of 240 mL / min, to obtain a two-dimensional silicon dioxide nanosheet-supported cobalt nanocomposite material.

[0075] The two-dimensional silica nanosheet-supported cobalt nanocomposite material prepared in the above embodiments was tested and analyzed.

[0076] Test 1: Morphological analysis and transmission electron microscopy analysis.

[0077] Morphology analysis was performed on the two-dimensional silica nanosheet-supported cobalt nanocomposites prepared in Examples 1 to 5. Some morphology images are shown below. Figure 1 and Figure 2 As shown.

[0078] As can be seen from the morphology image, the silica carrier exhibits a distinct two-dimensional nanosheet structure with cobalt nanoparticles loaded on its surface.

[0079] The two-dimensional silica nanosheets supported on cobalt nanocomposites prepared in Examples 1 to 5 were analyzed by transmission electron microscopy (TEM). Some TEM images are shown below. Figure 4 As shown. The full name of a transmission electron microscope is Transmission Electron Microscope, abbreviated as TEM.

[0080] Table 1 Effect of different calcination temperatures

[0081] Example Calcination temperature Size of nano-metal particles Size of two-dimensional silica nanosheets The thickness of two-dimensional silica nanosheets Example 1 600℃ 10~20nm 0.5~50 micrometers 100~500nm Example 2 950℃ 30~40nm 0.5~50 micrometers 200~1000nm Example 3 800℃ 15~25nm 0.5~50 micrometers 200~800nm Example 4 400℃ 5~10nm 0.5~50 micrometers 50~200nm Example 5 1000℃ 40~60nm 0.5~50 micrometers 500~1200nm

[0082] Based on Table 1 Figure 1 , Figure 2 and Figure 4 It is known that the surface of the two-dimensional silica nanosheets is loaded with uniformly distributed cobalt nanoparticles, with the particle size ranging from 10 nm to 20 nm. The size of the two-dimensional silica nanosheets ranges from 1 μm to 50 μm, and the thickness ranges from 20 nm to 200 nm. Furthermore, as the calcination temperature increases, the size of the metal nanoparticles gradually increases, and agglomeration also increases.

[0083] Test 2: X-ray diffraction analysis.

[0084] X-ray diffraction analysis was performed on the two-dimensional silica nanosheet-supported cobalt nanocomposites prepared in Examples 1 to 5. Some results are shown below. Figure 3 As shown. Co-2DSiO2 (950℃), Co-2DSiO2 (800℃), and Co-2DSiO2 (400℃) are the two-dimensional silica nanosheet-supported cobalt nanocomposites prepared in Examples 2, 3, and 4, respectively. Co-2DSiO2 is the two-dimensional silicon composite nanosheet powder before calcination. Si: PDF#75-0589; SiO2: PDF#46-1045; Co (Hexagonal): PDF#89-4308; Co (Cubic): PDF#15-0806 are the standard X-ray diffraction patterns of Si, SiO2, Co (hexagonal system), and Co (cubic system), respectively.

[0085] X-ray diffraction analysis revealed that the two-dimensional silica nanosheet-supported cobalt nanocomposite material mainly consists of silica and elemental cobalt under different annealing temperatures. Furthermore, with increasing annealing temperature, the crystal structure of elemental cobalt became stronger, while silica appeared simultaneously, which is attributed to the oxidation of Si at high temperatures.

[0086] Test 3: Electromagnetic absorption performance analysis.

[0087] Electromagnetic absorption properties of two-dimensional silica nanosheets supported on cobalt nanoparticles prepared at different calcination temperatures were analyzed, and the results are shown in Table 2. Tests were conducted at a thickness of 2.5 mm.

[0088] Table 2 Effect of calcination temperature on electromagnetic absorption performance

[0089] Calcination temperature Maximum absorption strength Effective absorption width 600℃ -45.2dB 3.2GHz 950℃ -32.5dB 1.6GHz 800℃ -42.3dB 4.2GHz 400℃ -51.6dB 4.6GHz 1000℃ -35.3dB 2.6GHz

[0090] The results in Table 2 show that the maximum absorption intensity reaches -42.3 dB to -51.6 dB when the calcination temperature is between 400 °C and 800 °C. Furthermore, the electromagnetic absorption capacity of the two-dimensional silica nanosheet-supported cobalt nanocomposite material is strongest at a calcination temperature of 400 °C. However, with further increases in calcination temperature, the maximum absorption intensity further decreases to -32.5 dB and -35.3 dB, indicating that excessively high calcination temperatures may weaken the electromagnetic absorption capacity of the material.

[0091] When the calcination temperature is between 400℃ and 800℃, the effective absorption bandwidth reaches 3.2GHz to 4.6GHz, and the electromagnetic absorption frequency range of the two-dimensional silica nanosheet-supported cobalt nanocomposite material is the widest at the calcination temperature of 400℃. When the calcination temperature is further increased to 950℃ and 1000℃, the effective absorption bandwidth further decreases to 1.6GHz and 2.6GHz, respectively, indicating that excessively high calcination temperatures may lead to a narrowing of the electromagnetic absorption frequency range of the material.

[0092] Electromagnetic absorption performance analysis was performed on cobalt nanomaterials supported on two-dimensional silica nanosheets of different thicknesses. The results are as follows: Figure 5 As shown in Table 3.

[0093] Table 3. Effect of thickness on electromagnetic absorption performance

[0094] thickness Maximum absorption strength Effective absorption width 1.0mm -5.2dB 0 1.5mm -9.3dB 0 2.0mm -17.3dB 2.4GHz 2.5mm -51.6dB 4.6GHz 3.0mm -24.5dB 5.3GHz 3.5mm -17.8dB 5.1GHz 4.0mm -14.5dB 4.7GHz 4.5mm -12.3dB 1.4GHz

[0095] Depend on Figure 5 The results show that the two-dimensional silica nanosheet-supported cobalt nanocomposite has a maximum absorption intensity of -51.6dB, an effective absorption width of 4.6GHz, and an optimal matching thickness of 2.5mm, exhibiting excellent electromagnetic absorption performance.

[0096] The above analysis shows that the heterostructure of the two-dimensional silica nanosheet-supported cobalt nanocomposite material prepared in the embodiments of the present invention can effectively construct a magnetoelectric synergistic system, promote polarization loss and conductivity loss, and effectively improve absorption intensity and absorption bandwidth.

[0097] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements 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 a two-dimensional silica nanosheet-supported metal microwave absorbing material, characterized in that, Includes the following steps: Silicides were stirred and mixed with a metal chloride-ethanol solution at a temperature of 50℃ to 90℃. The metal chloride was used to regulate the topological exfoliation process of the silicides to obtain a mixture of two-dimensional silica nanosheets. The mass ratio of silicides to metal chlorides was 1:0.1 to 3.

0. The mixture was then calcined at 400℃ to 800℃ and then reduced at 800℃ to 1200℃ in a reducing atmosphere to uniformly disperse single-domain-sized nano-metal particles on the two-dimensional silica nanosheets to form a heterostructure, thus obtaining a two-dimensional silica nanosheet-loaded metal absorbing material. The size of the nano-metal particles is 10 nm to 20 nm; the metal chloride salt is at least one of cobalt chloride, ferric chloride, nickel chloride, chromium chloride, and copper chloride; The maximum absorption intensity of the metal absorbing material supported on two-dimensional silica nanosheets reaches -42.3dB to -51.6dB, and the effective absorption bandwidth reaches 3.2GHz to 4.6GHz.

2. The method for preparing two-dimensional silica nanosheet-supported metal absorbing material according to claim 1, characterized in that, The two-dimensional silica nanosheets have a size of 1μm to 50μm and a thickness of 20nm to 200nm.

3. The method for preparing a two-dimensional silica nanosheet-supported metal absorbing material according to claim 1, characterized in that, The silicide is at least one of calcium silicide, magnesium silicide, iron silicide, copper silicide, and chromium silicide.

4. The method for preparing a two-dimensional silica nanosheet-supported metal absorbing material according to claim 1, characterized in that, The reducing atmosphere is a reducing gas or a mixture of a reducing gas and a protective gas; The reducing gas is hydrogen or carbon monoxide; the protective gas is nitrogen or argon.

5. The method for preparing a two-dimensional silica nanosheet-supported metal absorbing material according to claim 1, characterized in that, In a metal chloride-ethanol solution, the ratio of metal chloride to ethanol is 0.25g to 6g: 100mL.

6. A two-dimensional silica nanosheet-loaded metal absorbing material prepared by the preparation method according to any one of claims 1 to 5.

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