Carbon material loaded hydrotalcite nanosheet composite material, preparation method and application thereof

Abstract

The application provides a carbon material loaded hydrotalcite nanosheet composite material and a preparation method and application thereof, relates to the field of carbon-based composite materials, and the preparation method comprises the following steps: placing carbon material in two different hydrotalcite precursor solutions, and then performing a hydrothermal reaction, so that hydrotalcite nanosheets grow and crystallize in situ on the surface of a carbon skeleton to obtain a carbon / hydrotalcite composite material; wherein the hydrotalcite precursor solution contains metal ions, an alkali source and ammonium fluoride, and the hydrotalcite precursor solution contains metal ions and an alkali source. The application is based on the fact that carbon material is a dielectric material and has strong dielectric loss capability; the carbon material is used as a substrate, the hydrothermal reaction is performed to make hydrotalcite nanosheets grow in situ on the surface of the carbon material, and the obtained composite material inherits the dielectric properties of the carbon material and the flame-retardant properties of hydrotalcite. The composite material not only has strong dielectric loss, but also has excellent flame-retardant performance, thereby solving the problem of poor flame retardancy of wave-absorbing materials.

Description

Technical Field

[0001] This invention belongs to the field of carbon-based composite materials technology, specifically relating to a carbon-supported hydrotalcite nanosheet composite material, its preparation method, and its application. Background Technology

[0002] With the rapid development of electronic communication technology, electronic devices are rapidly evolving towards higher frequencies, greater integration, and miniaturization. This not only leads to serious electromagnetic radiation pollution and electromagnetic interference problems but also poses potential threats to human health and information security. Therefore, developing high-performance electromagnetic wave absorbing materials has become crucial for solving this problem. However, the heat accumulation generated during electromagnetic wave absorption and the heat accumulation in electronic devices can easily cause fires, especially in fields with extremely high safety requirements such as military applications, microwave anechoic chambers, communication base stations, and new energy vehicles. Materials in these areas not only need excellent electromagnetic wave attenuation capabilities but also reliable flame-retardant properties to prevent fires. Therefore, developing multifunctional electromagnetic wave absorbing composite materials that combine efficient electromagnetic wave absorption with flame-retardant properties has become a cutting-edge direction in materials science.

[0003] In the field of flame retardant materials, layered double hydroxides exhibit excellent flame retardant properties due to their unique two-dimensional layered structure, abundant interlayer water, and anions.

[0004] However, the direct introduction of flame retardants will inevitably reduce the electromagnetic wave absorption performance of the material. How to synergistically improve the electromagnetic wave absorption performance and flame retardant performance of composite materials remains a challenge. Summary of the Invention

[0005] The purpose of this invention is to solve the above problems and provide a method for preparing and applying a carbon-supported hydrotalcite nanosheet composite material, which can achieve both flame retardancy and electromagnetic wave absorption functions.

[0006] Specifically, the following steps are included: I. Preparation of carbon materials: Melamine foam is washed sequentially with deionized water and anhydrous ethanol. The washed melamine foam is then dried in an oven. The dried melamine foam is placed in a tube furnace and heated to the target temperature at a certain rate under an inert protective atmosphere and held at that temperature to obtain a carbon skeleton.

[0007] II. Preparation of hydrotalcite precursor solution: Accurately weigh cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, ammonium fluoride, and urea according to a certain ratio, then add them to a certain volume of deionized water and stir thoroughly to dissolve and form a homogeneous precursor solution 1; Accurately weigh magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and urea according to a certain ratio, then add them to a certain volume of deionized water and stir thoroughly to dissolve and form a homogeneous precursor solution 2.

[0008] III. Preparation of Composite Material: A certain mass of carbon material is added to the precursor solution and impregnated under vacuum. Then, it is transferred to a reaction vessel for hydrothermal reaction. After the reaction, the carbon material is removed, washed to remove impurities, and then dried in a vacuum drying oven to obtain the composite material.

[0009] In step one, the inert atmosphere is Ar gas, the target temperature is 900°C, the heating rate is 5°C / min, and the holding time is 2h.

[0010] In step two, the molar ratio of cobalt nitrate hexahydrate: aluminum nitrate nonahydrate: ammonium fluoride: urea is 2:1:5:70, and the volume of deionized water is 70 ml. In step two, the molar ratio of magnesium nitrate hexahydrate: aluminum nitrate nonahydrate: urea is 3:1:7, and the volume of deionized water is 60 ml.

[0011] The carbon material in step three has a mass of 100 mg; the vacuum impregnation vacuum degree is 10-50 Pa, and the holding time is 2 h; the hydrothermal reaction temperature is 120°C, and the holding time is 12 h; the vacuum drying temperature is 60°C, and the holding time is 12 h.

[0012] Beneficial effects of this invention: This invention provides a carbon-based composite material loaded with hydrotalcite nanosheets, achieving both electromagnetic wave absorption and flame retardancy. The introduction of hydrotalcite nanosheets adjusts impedance matching and enhances dielectric polarization loss. The carbon material forms a conductive network, facilitating electron transport and hopping, significantly improving conductivity and electromagnetic wave attenuation. Furthermore, the three-dimensional structure promotes multiple reflections, further attenuating electromagnetic waves. The carbon-based hydrotalcite nanosheet composite material has a carbon skeleton as its main body, surrounded by a layer of hydrotalcite nanosheets. This protective layer, completely covered by hydrotalcite, slows down or prevents the erosion of the composite material by open flame, resulting in good flame retardant properties. This invention provides applications of the above-mentioned carbon-based hydrotalcite nanosheet composite material, which serves as a microwave absorbing material in the 2-18 GHz frequency band and exhibits excellent flame retardant properties in open flame conditions. Attached Figure Description

[0013] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments: Figure 1 The XRD and SEM images are of the carbon framework supported on hydrotalcite nanosheets in Comparative Example 1. Figure 2 The reflection loss diagram is shown for the carbon skeleton supported by anhydrous talc nanosheets in Comparative Example 1. Figure 3 The XRD and SEM images of the two types of hydrotalcite nanosheets in Comparative Example 2 are shown. Figure 4 The reflection loss diagrams for the two types of hydrotalcite nanosheets in Comparative Example 2 are shown. Figure 5 The XRD pattern and microstructure of the carbon skeleton-supported hydrotalcite nanosheet composite material in Example 1 are shown. Figure 6 The XRD pattern and microstructure of the carbon skeleton-supported hydrotalcite nanosheet composite material in Example 2 are shown. Figure 7 The image shows the reflection loss of the carbon skeleton-supported hydrotalcite nanosheet composite material in Example 1. Figure 8 The image shows the reflection loss of the carbon skeleton-supported hydrotalcite nanosheet composite material in Example 2. Figure 9 The flame retardant properties of the carbon skeleton-supported hydrotalcite nanosheet composite material in Example 1 and the carbon skeleton without hydrotalcite support were tested.

[0014] Figure 10 The flame retardant properties of the carbon skeleton-supported hydrotalcite nanosheet composite material and the carbon skeleton without hydrotalcite support in Example 2 were tested. Detailed Implementation

[0015] The present invention will be further explained below with reference to specific implementation schemes, but it is not limited to the present invention. The structures, proportions, sizes, etc. shown in the accompanying drawings are only used to complement the content disclosed in the specification, so as to enable those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effect and purpose that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are for illustrative purposes only and do not constitute any limitation on the scope of protection of this invention.

[0017] The specific solution of the present invention is as follows: A method for preparing a carbon-supported hydrotalcite nanosheet composite material is provided, comprising the following steps: I. Preparation of carbon materials: Melamine foam is washed sequentially with deionized water and anhydrous ethanol. The washed melamine foam is then dried in an oven. The dried melamine foam is placed in a tube furnace and heated to the target temperature at a certain rate under an inert protective atmosphere and held at that temperature to obtain carbon materials.

[0018] II. Preparation of hydrotalcite precursor solution: Accurately weigh cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, ammonium fluoride, and urea according to a certain ratio, then add them to a certain volume of deionized water and stir thoroughly to dissolve and form a homogeneous precursor solution 1; Accurately weigh magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and urea according to a certain ratio, then add them to a certain volume of deionized water and stir thoroughly to dissolve and form a homogeneous precursor solution 2. III. Preparation of Composite Material: A certain mass of carbon material is added to the precursor solution and impregnated under vacuum. Then, it is transferred to a reaction vessel for hydrothermal reaction. After the reaction, the carbon material is removed, washed to remove impurities, and then dried in a vacuum drying oven to obtain the composite material.

[0019] The present invention will be further described below with reference to specific embodiments and comparative examples.

[0020] Example 1 This embodiment provides a method for preparing a carbon-supported hydrotalcite nanosheet composite material, including the following steps: I. Preparation of carbon materials: Melamine foam is washed sequentially with deionized water and anhydrous ethanol. The washed melamine foam is then dried in an oven. The dried melamine foam is placed in a tube furnace and heated to the target temperature at a certain rate under an inert protective atmosphere and held at that temperature to obtain carbon materials.

[0021] II. Preparation of hydrotalcite precursor solution: Accurately weigh cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, ammonium fluoride, and urea according to a certain ratio, then add them to a certain volume of deionized water and stir thoroughly to dissolve and form a homogeneous precursor solution 1.

[0022] III. Preparation of Composite Material: A certain mass of carbon material was added to precursor solution 1 and vacuum impregnated. Then, it was transferred to a reaction vessel for hydrothermal reaction. After the reaction, the carbon material was removed, washed to remove impurities, and then dried in a vacuum drying oven to obtain the composite material.

[0023] In step one, the inert atmosphere is Ar gas, the target temperature is 900°C, the heating rate is 5°C / min, and the holding time is 2h.

[0024] In step two, the molar ratio of cobalt nitrate hexahydrate: aluminum nitrate nonahydrate: ammonium fluoride: urea is 2:1:5:70, and the volume of deionized water is 70 ml. The carbon skeleton in step three has a mass of 100 mg; the vacuum impregnation vacuum degree is 10-50 Pa, and the holding time is 2 h; the hydrothermal reaction temperature is 120°C, and the holding time is 12 h; the vacuum drying temperature is 60°C, and the holding time is 12 h.

[0025] Figure 5 The images show the XRD pattern and microstructure of the carbon-supported hydrotalcite nanosheet composite material prepared in this embodiment. From... Figure 5 As can be seen, the successful synthesis of hydrotalcite and carbon materials exhibits a shell-core structure.

[0026] Figure 7 The reflection loss diagrams for the prepared carbon-supported hydrotalcite nanosheet composites are shown in the 2–18 GHz range. Figure 7 As can be seen, the composite material exhibits the best microwave absorption performance. When the absorber thickness is 1.7 mm, the maximum reflection loss of the material is -51.8 dB; when the absorber thickness is 1.8 mm, the effective bandwidth of the material is 5.2 GHz, demonstrating excellent high-bandwidth microwave absorption performance.

[0027] Figure 9 This study tested the flame retardant properties of the carbon skeleton-supported hydrotalcite nanosheet composite material from Example 1 compared to a carbon skeleton without hydrotalcite support. Figure 9 As can be seen, the carbon material without hydrotalcite loading burned completely during the test; the carbon material-loaded hydrotalcite nanosheet composite material did not burn, demonstrating excellent flame retardant ability.

[0028] Example 2 This embodiment provides a method for preparing a carbon-supported hydrotalcite nanosheet composite material, including the following steps: I. Preparation of carbon materials: Melamine foam is washed sequentially with deionized water and anhydrous ethanol. The washed melamine foam is then dried in an oven. The dried melamine foam is placed in a tube furnace and heated to the target temperature at a certain rate under an inert protective atmosphere and held at that temperature to obtain carbon materials.

[0029] II. Preparation of hydrotalcite precursor solution: Accurately weigh magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and urea according to a certain ratio, then add them to a certain volume of deionized water and stir thoroughly to dissolve and form a homogeneous precursor solution 2.

[0030] III. Preparation of Composite Material: A certain mass of carbon material was added to precursor solution 2 and vacuum impregnated. Then, it was transferred to a reaction vessel for hydrothermal reaction. After the reaction, the carbon skeleton was removed, washed to remove impurities, and then dried in a vacuum drying oven to obtain the composite material.

[0031] In step one, the inert atmosphere is Ar gas, the target temperature is 900°C, the heating rate is 5°C / min, and the holding time is 2h.

[0032] In step two, the molar ratio of magnesium nitrate hexahydrate: aluminum nitrate nonahydrate: urea is 3:1:7, and the volume of deionized water is 60 ml.

[0033] The carbon material in step three has a mass of 100 mg; the vacuum impregnation vacuum degree is 10-50 Pa, and the holding time is 2 h; the hydrothermal reaction temperature is 120°C, and the holding time is 12 h; the vacuum drying temperature is 60°C, and the holding time is 12 h.

[0034] Figure 6 The images show the XRD pattern and microstructure of the carbon-supported hydrotalcite nanosheet composite material prepared in this embodiment. From... Figure 6 As can be seen, the successful synthesis of hydrotalcite and carbon materials exhibits a shell-core structure.

[0035] Figure 8 The reflection loss diagrams for the prepared carbon-supported hydrotalcite nanosheet composites are shown in the 2–18 GHz range. Figure 8 As can be seen, the composite material exhibits the best microwave absorption performance. When the absorber thickness is 1.6 mm, the maximum reflection loss of the material is -43.12 dB; when the absorber thickness is 2.0 mm, the effective bandwidth of the material is 6.32 GHz, demonstrating excellent high-bandwidth microwave absorption performance.

[0036] Figure 10 This study tested the flame retardant properties of the carbon skeleton-supported hydrotalcite nanosheet composite material and the carbon skeleton without hydrotalcite support in Example 2. Figure 10 As can be seen, the carbon material without hydrotalcite loading burned completely during the test; the carbon material-loaded hydrotalcite nanosheet composite material did not burn, demonstrating excellent flame retardant ability.

[0037] Comparative Example 1 This comparative example provides a method for preparing carbon materials supported on anhydrous talc nanosheets, including the following steps: Melamine foam was washed sequentially with deionized water and anhydrous ethanol, and then dried in an oven. The dried melamine foam was then placed in a tube furnace and heated to a target temperature at a controlled rate under an inert atmosphere, and held at that temperature to obtain carbon material. In this process, the inert atmosphere was Ar gas, the target temperature was 900°C, the heating rate was 5°C / min, and the holding time was 2 hours.

[0038] Figure 1 The images show the XRD and SEM images of the carbon material supported on anhydrous talc nanosheets prepared in this embodiment. Figure 1 As shown in (a), carbon materials were successfully prepared without any other impurity phases. Figure 1 In (b), the carbon material has a smooth surface and a three-dimensional skeleton.

[0039] Figure 2 The reflection loss diagram is shown for the carbon material supported on the prepared anhydrous talc nanosheets. From... Figure 2 As can be seen, pure carbon materials have poor electromagnetic wave loss capability.

[0040] Comparative Example 2 This comparative example provides a method for preparing hydrotalcite nanosheets, specifically including the following steps: Preparation of hydrotalcite precursor solution: Accurately weigh cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, ammonium fluoride, and urea according to a certain ratio, then add them to a certain volume of deionized water and stir thoroughly to dissolve and form a homogeneous precursor solution 1; Accurately weigh magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and urea according to a certain ratio, then add them to a certain volume of deionized water and stir thoroughly to dissolve and form a homogeneous precursor solution 2.

[0041] Preparation of hydrotalcite nanosheets: The precursor solutions were transferred to a reaction vessel for hydrothermal reaction; after the reaction was completed, the materials were washed to remove impurities, and then dried in a vacuum drying oven to obtain hydrotalcite nanosheets.

[0042] In step one, the molar ratio of cobalt nitrate hexahydrate: aluminum nitrate nonahydrate: ammonium fluoride: urea is 2:1:5:70, and the volume of deionized water is 70 ml.

[0043] In step one, the molar ratio of magnesium nitrate hexahydrate: aluminum nitrate nonahydrate: urea is 3:1:7, and the volume of deionized water is 60 ml.

[0044] In step two, the vacuum impregnation vacuum degree is 10-50 Pa, the pressure holding time is 2 h; the hydrothermal reaction temperature is 120°C, the holding time is 12 h; and the vacuum drying temperature is 60°C, the holding time is 12 h.

[0045] Figure 3 The images show the XRD and SEM images of the two types of hydrotalcite nanosheets prepared in this embodiment. Figure 1 As shown in (a), hydrotalcite nanosheets were successfully prepared without any other impurities. Figure 1 As can be seen in (b), the hydrotalcite has a flaky morphology.

[0046] Figure 4 The image shows the reflection loss diagrams of the two types of carbon materials supported on hydrotalcite nanosheets. From... Figure 4 As can be seen, hydrotalcite nanosheets do not have the ability to lose electromagnetic waves.

[0047] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0048] Matters not covered in this invention are common knowledge.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a carbon-supported hydrotalcite nanosheet composite material, characterized in that: Excellent electromagnetic wave absorption and flame retardant properties can be obtained by using hydrotalcite to control morphology, impedance matching and heterogeneous interfaces. The carbon-supported hydrotalcite nanosheet composite material is characterized by having a shell-core structure, wherein the hydrotalcite nanosheets form the outer shell and the carbon material forms the core.

2. A method for preparing the carbon-supported hydrotalcite nanosheet composite material according to claim 1, characterized in that: Includes the following steps: I. Preparation of carbon materials: Melamine foam is washed sequentially with deionized water and anhydrous ethanol. The washed melamine foam is then dried in an oven. The dried melamine foam is placed in a tube furnace and heated to the target temperature at a certain rate under an inert protective atmosphere and held at that temperature to obtain carbon materials. II. Preparation of hydrotalcite precursor solution: Accurately weigh cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, ammonium fluoride, and urea according to a certain ratio, then add them to a certain volume of deionized water and stir thoroughly to dissolve and form a homogeneous precursor solution 1; Accurately weigh magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and urea according to a certain ratio, then add them to a certain volume of deionized water and stir thoroughly to dissolve and form a homogeneous precursor solution 2. III. Preparation of composite materials: A certain mass of carbon material is added to the precursor solution and vacuum impregnated; The carbon material was then transferred to a reactor for hydrothermal reaction. After the reaction was completed, the carbon material was removed, washed to remove impurities, and then dried in a vacuum drying oven to obtain the composite material.

3. The method for preparing the carbon-supported hydrotalcite nanosheet composite material according to claim 2, characterized in that: In step one, the inert atmosphere is Ar gas, the target temperature is 900°C, the heating rate is 5°C / min, and the holding time is 2h.

4. The method for preparing carbon-supported hydrotalcite nanosheet composite material according to claim 2, characterized in that: In step two, the molar ratio of cobalt nitrate hexahydrate: aluminum nitrate nonahydrate: ammonium fluoride: urea is 2:1:5:70, and the volume of deionized water is 70 ml; in step two, the molar ratio of magnesium nitrate hexahydrate: aluminum nitrate nonahydrate: urea is 3:1:7, and the volume of deionized water is 60 ml.

5. The method for preparing the carbon framework-supported hydrotalcite nanosheet composite material according to claim 2, characterized in that, The carbon skeleton in step three has a mass of 100 mg; the vacuum impregnation vacuum degree is 10-50 Pa, and the holding time is 2 h; the hydrothermal reaction temperature is 120°C, and the holding time is 12 h; the vacuum drying temperature is 60°C, and the holding time is 12 h.

6. A carbon-framework-supported hydrotalcite nanosheet composite material, characterized in that, The carbon-supported hydrotalcite nanosheet composite material is obtained by the preparation method described in any one of claims 1 to 5; the carbon-supported hydrotalcite nanosheet composite material has a core-shell structure and is formed by electrostatic self-assembly.

7. The application of the carbon-supported hydrotalcite nanosheet composite material according to claim 6, characterized in that, The carbon-supported hydrotalcite nanosheet composite material serves as a microwave absorbing material in the 2-18 GHz frequency band and exhibits excellent flame retardant properties in alcohol lamp combustion experiments.

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