Preparation method of structural reinforced magnetic graphene aerogel wave-absorbing material

Abstract

The application provides a preparation method of structure-enhanced magnetic graphene aerogel wave-absorbing material, and comprises the following steps: S1, preparing graphene oxide solution by taking graphite flake as raw material; S2, weighing iron chloride, fumaric acid and deionized water, stirring to dissolve and then hydrolyzing; collecting the precipitate by centrifugation, drying after washing to obtain iron-based metal organic framework; S3, placing the iron-based metal organic framework obtained in step S2 in air, pyrolyzing to obtain ferroferric oxide nanorod, mixing the ferroferric oxide nanorod with deionized water, ultrasonic dispersing, adding graphene oxide solution and hydrazine hydrate, ultrasonic treating and then hydrolyzing to form hydrogel, soaking, freeze-drying to obtain composite aerogel; S4, heat-treating the composite aerogel in N2 atmosphere to obtain structure-enhanced magnetic graphene aerogel. The magnetic nanorod derived from the iron-based metal organic framework is introduced into the graphene aerogel, which can not only improve the wave-absorbing intensity and absorption bandwidth, but also improve the compression resistance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of wave-absorbing materials, in particular to a preparation method of a structure-enhanced magnetic graphene aerogel wave-absorbing material. BACKGROUND

[0002] The difference in the concealment of various radar detection signals of naval equipment will largely determine the combat capability of the navy. Therefore, the stealth of naval vessels is increasingly concerned. Since the radar detection distance is far and is less affected by the climate, the radar detection is the most commonly used means of long-range detection and guided anti-ship weapons, and therefore, the radar detection poses the greatest threat to the vessels. Therefore, the radar wave stealth technology has become the focus and symbol of the stealth technology of surface vessels. Graphene is considered to be a strong candidate for a new generation of wave-absorbing materials due to its unique dielectric properties, high specific surface area, low density and other properties. However, the wave-absorbing performance of single-component graphene is poor, and therefore, in recent years, graphene-based wave-absorbing composite materials have become a research hotspot.

[0003] The biggest problem of the prepared graphene aerogel is that it cannot withstand high external force and the electromagnetic loss is single, which is due to the disordered self-assembly process of the aerogel, resulting in its being too fragile. In view of the problem of single loss, the method of magnetic-electric composite is mainly used at present to solve the problem. For example: Chinese patent CN202210170315.5 discloses a Fe-MOF derived graphene-based composite aerogel wave-absorbing material and a preparation method. The invention exhibits excellent wave-absorbing intensity and wide-frequency absorption characteristics due to the magnetic-electric composite. Chinese patent CN202310076464.X provides a nano Fe3O4-graphene aerogel composite wave-absorbing material and a preparation method thereof. The preparation method uses fewer types of chemical reagents, and the experimental steps are safe and simple. The obtained composite wave-absorbing material has an extremely low density, and when the addition amount is only 5wt%, the wave-absorbing intensity can reach-61.5dB, and the effective absorption bandwidth is 7.7GHz, which exhibits excellent wave-absorbing performance. However, the composite material prepared by the prior art cannot well overcome the weak compression resistance defect. SUMMARY

[0004] Therefore, the application aims to provide a preparation method of a structure-enhanced magnetic graphene aerogel wave-absorbing material to solve the problems of weak compression resistance and single electromagnetic loss of the graphene aerogel.

[0005] To achieve the above-mentioned purpose, the technical scheme of the application is as follows:

[0006] The application provides a preparation method of a structure-enhanced magnetic graphene aerogel wave-absorbing material.

[0007] S1. Using graphite flakes as raw materials, an improved Hummers method is used to prepare an oxidized graphene solution;

[0008] S2. Respectively, take iron chloride, fumaric acid and deionized water, stir to dissolve and then hydrolyze; then centrifugal collection of precipitate product, and respectively use deionized water and ethanol to wash thoroughly, and then place in vacuum oven to dry to obtain iron-based metal organic framework;

[0009] S3. The iron-based metal organic framework obtained in step S2 is placed in air, pyrolysis to obtain ferroferric oxide nanorod, and then the ferroferric oxide nanorod and deionized water are mixed and ultrasonically dispersed, then the graphene oxide solution and hydrazine hydrate are added, and after ultrasonic treatment, hydrolysis reaction is carried out to form hydrogel, and then the obtained hydrogel is soaked in deionized water and freeze-dried to obtain composite aerogel;

[0010] S4. The composite aerogel obtained in step S3 is placed in N2 atmosphere and heat treated to obtain structure-enhanced magnetic graphene aerogel.

[0011] Among them, the improved Hummers method is prior art, which will not be described in detail here.

[0012] Further, in step S2, the hydrolysis temperature is 85℃, and the time is 18-24h.

[0013] Further, in step S2, the amount of iron chloride, fumaric acid and deionized water is 1g: 10g: 100mL.

[0014] Further, in step S2, the drying temperature is 60-80℃, and the drying time is 12-15h.

[0015] Further, in step S3, the pyrolysis temperature is 380℃, and the pyrolysis time is 60min.

[0016] Further, in step S3, the amount of ferroferric oxide nanorod, deionized water and graphene oxide solution is 2.5-10mg: 1mL: 1mL.

[0017] Further, in step S3, the hydrolysis temperature is 180℃, and the time is 12-15h.

[0018] Further, in step S4, the composite aerogel is placed in 700℃ N2 atmosphere and heat treated for 10-15min.

[0019] Compared with the prior art, the preparation method of the structural reinforced magnetic graphene aerogel wave-absorbing material has the following advantages: the iron-based metal organic framework derived magnetic nanorods are introduced into the graphene aerogel, which not only improves the wave-absorbing intensity and absorption bandwidth, but also supports the graphene network through the magnetic nanorods to improve the compression resistance, and a wide frequency domain absorption of 10-18GHz can be achieved with a very small filling ratio, the prepared graphene aerogel wave-absorbing material has the characteristics of "thin, wide, light and strong", and has certain economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and serve as an explanation of the illustrative embodiments of the present application and their description, and do not constitute improper limitations on the present application. In the drawings:

[0021] Figure 1 One of the micro-morphology diagrams of the magnetic graphene aerogel prepared for Example 1 of the present application;

[0022] Figure 2 The second micro-morphology diagram of the magnetic graphene aerogel prepared for Example 1 of the present application;

[0023] Figure 3 The hysteresis loop of the aerogel of Example 1-3 and Comparative Example 1 of the present application;

[0024] Figure 4 The compression resistance results of the aerogel of Example 1-3 and Comparative Example 1 of the present application;

[0025] Figure 5 The wave-absorbing performance diagram of the aerogel of Example 1-3 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0026] The present application will be further described below in conjunction with specific embodiments. It should be first pointed out that the data in the following experimental examples are obtained by the inventors through a large number of experiments, and only a part of them are shown in the specification due to the limited space, and the ordinary skilled in the art can understand and implement the present application based on the data. These examples are only used to illustrate the present application and not to limit the scope of the present application. In addition, it should be understood that after reading the content of the present application, those skilled in the art can make various modifications or modifications to the present application, and these modifications or modifications also fall within the scope of the present application.

[0027] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0028] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0029] Example 1

[0030] Step 1: Graphite oxide solution was prepared by improved Hummers method using graphite flake as raw material.

[0031] Step 2: 0.5 g of iron chloride and 5 g of fumaric acid were dissolved in 50 mL of deionized water, and after stirring to completely dissolve, it was transferred to a polytetrafluoroethylene lined reactor, and reacted at 85°C for 24 hours. Then the precipitated product was collected by centrifugation and washed with deionized water and ethanol respectively. Then it was dried in a vacuum oven at 60°C for 12 hours to obtain the iron-based metal organic framework.

[0032] Step 3: The iron-based metal organic framework obtained in step 2 was placed in air and pyrolyzed at a temperature of 380°C for 60 minutes to obtain iron trioxide nanorods. Then 25 mg of iron trioxide nanorods were dispersed in 10 mL of deionized water, and after ultrasonic dispersion, they were mixed with 10 mL of graphene oxide solution (5 mg / mL) to obtain a mixture. 0.5 mL of hydrazine hydrate (3 wt%) was added to the above mixture, and ultrasonic treatment was carried out for 1 hour. Then the ultrasonic treated solution was transferred to a polytetrafluoroethylene lined reactor and reacted at 180°C for 12 hours to form a hydrogel. The obtained hydrogel was soaked in deionized water for one week, and after freeze-drying, a composite aerogel was obtained.

[0033] Step 4: The composite aerogel obtained in step 3 was heat treated at 700°C in N2 atmosphere for 10 minutes to obtain a structure-enhanced magnetic graphene aerogel, denoted as GA-1.

[0034] Example 2

[0035] Step 1: Graphite oxide solution was prepared by improved Hummers method using graphite flake as raw material.

[0036] Step 2: 0.5 g of iron chloride and 5 g of fumaric acid were dissolved in 50 mL of deionized water, and after stirring to completely dissolve, it was transferred to a polytetrafluoroethylene lined reactor, and reacted at 85°C for 24 hours. Then the precipitated product was collected by centrifugation and washed with deionized water and ethanol respectively. Then it was dried in a vacuum oven at 60°C for 12 hours to obtain the iron-based metal organic framework.

[0037] Step 3: The iron-based metal organic framework obtained from step 2 was pyrolyzed in air at a temperature of 380 °C for 50 min to obtain the iron oxide nanorods. Subsequently, 50 mg of the iron oxide nanorods were dispersed in 10 mL of deionized water, and after ultrasonic dispersion, mixed with 10 mL of graphene oxide dispersion (5 mg / mL) to obtain a mixture. 0.5 mL of hydrazine hydrate (3 wt%) was added to the above mixture, and ultrasonic treatment was performed for 1.5 h. Then, the ultrasonically treated solution was transferred to a polytetrafluoroethylene-lined reactor, and reacted at 180 °C for 12 h to form a hydrogel. The obtained hydrogel was soaked in deionized water for one week, and a composite aerogel was obtained by freeze-drying.

[0038] Step 4: The composite aerogel obtained from step 3 was heat-treated in a N2 atmosphere at 700 °C for 10 min to obtain a structure-enhanced magnetic graphene aerogel, denoted as GA-2.

[0039] Example 3

[0040] Step 1: Graphene oxide solution was prepared using a modified Hummers method with graphite flakes as raw material.

[0041] Step 2: 0.5 g of iron chloride and 5 g of fumaric acid were dissolved in 50 mL of deionized water, and after stirring to completely dissolve, were transferred to a polytetrafluoroethylene-lined reactor and reacted at 85 °C for 18 h. Subsequently, the precipitated product was collected by centrifugation and washed thoroughly with deionized water and ethanol, respectively. Then, the iron-based metal organic framework was dried in a vacuum oven at 60 °C for 15 h.

[0042] Step 3: The iron-based metal organic framework obtained from step 2 was pyrolyzed in air at a temperature of 380 °C for 50 min to obtain the iron oxide nanorods. Subsequently, 50 mg of the iron oxide nanorods were dispersed in 10 mL of deionized water, and after ultrasonic dispersion, mixed with 10 mL of graphene oxide dispersion (5 mg / mL) to obtain a mixture. 0.5 mL of hydrazine hydrate (3 wt%) was added to the above mixture, and ultrasonic treatment was performed for 1.5 h. Then, the ultrasonically treated solution was transferred to a polytetrafluoroethylene-lined reactor, and reacted at 180 °C for 12 h to form a hydrogel. The obtained hydrogel was soaked in deionized water for one week, and a composite aerogel was obtained by freeze-drying.

[0043] Step 4: The composite aerogel obtained from step 3 was heat-treated in a N2 atmosphere at 700 °C for 10 min to obtain a structure-enhanced magnetic graphene aerogel, denoted as GA-2.

[0044] Comparative Example 1

[0045] Step 1: Graphene oxide solution was prepared using a modified Hummers method with graphite flakes as raw material.

[0046] Step 2, 0.5 mL of hydrazine hydrate (3 wt%) was added into 10 mL of graphene oxide solution (5 mg / mL) and ultrasonically treated for 1 h. Then the mixture was transferred into a polytetrafluoroethylene lined reactor and reacted at 180℃ for 12 h to form a hydrogel, and the obtained hydrogel was soaked in deionized water for one week. Finally, the graphene aerogel was obtained by freeze-drying, which was denoted as GA.

[0047] Test method and sample performance analysis:

[0048] The microstructure of the structure-reinforced magnetic graphene aerogel composite wave-absorbing material prepared by the method of the present application was observed by electron microscopy. The added iron had a rod-like morphology and was uniformly interpenetrated between the graphene layers, which played a good supporting role for the three-dimensional structure of graphene. The graphene aerogel can have magnetic properties and better compression resistance. The graphene aerogel prepared by the method of the present application has the same microstructure. Due to the limited space, in the present application, Example 1 is taken as an example, and only the microstructure of the graphene aerogel prepared in Example 1 is shown, as shown in FIG. 1, the nanorods are uniformly interpenetrated between the graphene layers, which plays a supporting role for the three-dimensional structure of graphene, making the graphene aerogel have better compression resistance. Figures 1-2 Figure 2 The lattice spacing of 0.206 nm corresponds to the (222) crystal plane of Fe3O4, indicating that the nanorods are composed of Fe3O4, which makes the graphene aerogel have magnetic properties, thereby improving the wave-absorbing performance. As shown in FIG. 3, the hysteresis loop of the graphene aerogel prepared in Example 1-3, when used as a wave-absorbing material, the maximum reflection loss is -52.77 dB. Figure 3

[0049] As shown in FIG. 4, the compression resistance data of the graphene aerogel. The maximum weight that the aerogel of Comparative Example 1 can withstand is 2659 times its own weight. The maximum weight that the graphene aerogels of Examples 1-3 can withstand is 3195 times, 3546 times and 4065 times its own weight, respectively, indicating that the introduction of iron-based metals in the magnetic graphene gel prepared by the method of the present application can play a good supporting role and enhance the structure. Figure 4 The graphene aerogels prepared in Examples 1-3 and Comparative Example 1 were soaked in molten paraffin, and then placed in a vacuum drying oven and heated to vacuum for 1 h. Then, cooling and solidification were performed to prepare a circular ring sample with an inner diameter of 3.04 mm and an outer diameter of 7.00 mm. The electromagnetic parameter test was performed using a vector network analyzer, and the reflection loss performance data was obtained by calculation, as shown in FIG. 5.

[0050] Figure 5 ​​​Compared with the simple graphene aerogel of Comparative Example 1, the structure-reinforced magnetic graphene aerogel composite wave-absorbing material prepared in Examples 1-3 exhibits more excellent wave-absorbing performance. In particular, the effective absorption bandwidth of the aerogel of Example 3 can reach 7.36 GHz (10.64 GHz-18 GHz).

[0051] Compared with the graphene aerogel in the prior art which can only satisfy one of high strength or good wave-absorbing performance, the present application provides a preparation method of structure-reinforced magnetic graphene aerogel composite wave-absorbing material. By adjusting various parameters, magnetic ferroferric oxide can be introduced onto graphene in the form of rods, thereby introducing magnetic loss into graphene, and the graphene network structure is supported by the magnetic nanorods, so that the magnetic graphene aerogel with excellent compression resistance and wave-absorbing performance can be prepared, and the goals of thin absorption bandwidth, wide absorption bandwidth, light weight and high wave-absorbing strength are achieved.

[0052] The above merely describes preferred embodiments of the present application but should not be used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a structurally reinforced magnetic graphene aerogel wave-absorbing material, characterized in that, Comprising the following steps: S1. Using graphite flake as raw material, graphene oxide solution is prepared by improved Hummers method; S2. Iron chloride, fumaric acid and deionized water are weighed respectively, stirred to dissolve and then hydrolyzed; the precipitate is collected by centrifugation, washed with deionized water and ethanol respectively, and then dried in a vacuum oven to obtain iron-based metal organic framework; S3. The iron-based metal organic framework obtained in step S2 is placed in air, pyrolyzed at 380℃ for 60min to obtain ferroferric oxide nanorods; the ferroferric oxide nanorods and deionized water are mixed and ultrasonically dispersed, then the graphene oxide solution and hydrazine hydrate are added, ultrasonically treated and then hydrolyzed to form hydrogel at 180℃ for 12-15h; the obtained hydrogel is soaked in deionized water and freeze-dried to obtain composite aerogel; S4. The composite aerogel obtained in step S3 is heat-treated in N2 atmosphere, which can introduce magnetic ferroferric oxide in rod-like morphology into graphene to obtain structure-enhanced magnetic graphene aerogel.

2. The method for preparing the structure-enhanced magnetic graphene aerogel microwave absorbing material according to claim 1, characterized in that, In step S2, the hydrolysis temperature is 85℃ and the time is 18-24h.

3. The method of claim 1, wherein the structural reinforced magnetic graphene aerogel wave absorbing material is prepared by the following steps: (1) preparing a magnetic graphene oxide solution; (2) preparing a magnetic graphene oxide aerogel; (3) preparing a structural reinforced magnetic graphene oxide aerogel; (4) preparing a structural reinforced magnetic graphene aerogel. In step S2, the amount ratio of iron chloride, fumaric acid and deionized water is 1g:10g:100mL.

4. The method for preparing the structure-enhanced magnetic graphene aerogel microwave absorbing material according to claim 1, characterized in that, In step S2, the drying temperature is 60-80℃ and the drying time is 12-15h.

5. The method for preparing the structure-enhanced magnetic graphene aerogel microwave absorbing material according to claim 1, characterized in that, In step S3, the amount ratio of ferroferric oxide nanorods, deionized water and graphene oxide solution is 2.5-10mg:1mL:1mL.

6. The method of claim 1, wherein the structural reinforced magnetic graphene aerogel wave absorbing material is prepared by the steps of: In step S4, the composite aerogel is heat-treated in N2 atmosphere at 700℃ for 10-15min.

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