Preparation method and application of adjustable reduced graphene oxide broadband wave-absorbing material

Abstract

The invention belongs to the technical field of preparation and application of wave-absorbing materials, and particularly relates to a preparation method and application of an adjustable reduced graphene oxide broadband wave-absorbing material. The preparation method comprises the following steps: ultrasonically stirring and mixing graphene oxide prepared by Hummers and ultrapure water, freeze-drying the obtained GO suspension, and performing micro-reduction at a certain temperature to obtain the rGO wave-absorbing material. The wave-absorbing performance of the micro-reduced graphene oxide is regulated and controlled by modulating different reduction degrees and different pore sizes, the EAB value of the rGO material can reach 7.98 GHz, the Ku band frequency is completely covered, and the excellent broadband wave-absorbing performance is shown.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation and application of wave-absorbing materials, and in particular relates to a preparation method and application of an adjustable reduced graphene oxide broadband wave-absorbing material. Background Art

[0002] The rapid development of 5G technology has greatly improved production efficiency and quality of life. With the continuous advancement of electronic equipment, mobile communications and wireless networks, the transmission and reception of electronic signals inevitably cause electromagnetic pollution. Electromagnetic pollution caused by electromagnetic interference and radiation seriously endangers information security and human health. Microwaves directly interfere with the normal operation of electronic equipment, causing them to fail or even be scrapped. The absorption of electromagnetic waves is crucial to the advancement of electromagnetic technology and the development of complex equipment, and has broad prospects in the fields of national defense, transportation, aerospace and health care. Graphene-based materials have a unique two-dimensional flexible sheet morphology, coupled with their adjustable conductivity and multiple scattering of electromagnetic waves between sheets, making graphene a highly potential microwave absorber. Most absorbing materials only achieve high absorption performance at a certain frequency, but how to achieve broadband absorption performance in the 2-18 GHz frequency band has always been a great challenge. The present invention successfully prepared rGO absorbing materials that can be simply adjusted using reduced graphene oxide as raw materials to achieve efficient broadband electromagnetic wave absorption. Summary of the invention

[0003] The purpose of the present invention is to provide a preparation method and application of an adjustable reduced graphene oxide broadband absorbing material, wherein the absorbing material utilizes the electromagnetic resonance absorbing mechanism, and the high electromagnetic loss capacity and three-dimensional structure of micro-reduced graphene oxide work synergistically to effectively improve the absorbing performance and achieve a broadband absorbing effect.

[0004] The technical solution adopted by the present invention is:

[0005] A method for preparing a tunable reduced graphene oxide broadband wave absorbing material comprises the following steps:

[0006] 1) Mixing graphene oxide GO prepared by Hummers with ultrapure water by ultrasonic stirring to obtain a GO suspension, and freeze-drying to obtain GO aerogel;

[0007] 2) placing the GO aerogel obtained in step 1) in a tubular furnace, exhausting the air in the tubular furnace by passing argon gas under an argon atmosphere, heating to a certain temperature for micro-reduction, and obtaining an rGO absorbing material.

[0008] Preferably, in the above preparation method, in step 1), the concentration of GO in the GO suspension is 1.25-15 mg / mL.

[0009] More preferably, in the above preparation method, in step 1), the concentration of GO in the GO suspension is 5 mg / mL.

[0010] Preferably, in the above-mentioned preparation method, in step 1), the freeze drying is performed at -60°C to -80°C for 48 to 96 hours.

[0011] More preferably, in the above preparation method, in step 1), the freeze drying is freezing under liquid nitrogen and freeze drying at -80°C for 48 hours.

[0012] Preferably, in the above-mentioned preparation method, in step 2), the time of passing argon gas is 30 to 60 minutes.

[0013] More preferably, in the above preparation method, in step 2), the time of passing argon gas is 30 minutes.

[0014] Preferably, in the above-mentioned preparation method, in step 2), the micro-reduction is performed by heating the temperature to 180°C to 330°C at a rate of 3 to 7°C / min for 0.5 to 4 hours.

[0015] More preferably, in the above preparation method, in step 2), the micro-reduction is performed at 260° C. at a heating rate of 5° C. / min for 2.5 hours.

[0016] Application of the rGO absorbing material prepared by any of the preparation methods described above in microwave absorption.

[0017] The beneficial effects of the present invention are:

[0018] 1. The rGO absorbing material prepared by the present invention can effectively absorb electromagnetic waves and has excellent broadband absorbing performance.

[0019] 2. The preparation method provided by the present invention can regulate the morphology and structure of the material by improving the synthesis strategy and adjusting the concentration of graphene oxide, so that it has a more suitable specific surface area and pore volume, and at the same time increases the interaction opportunity between the absorbing material and the electromagnetic wave, meeting the requirements of lightweight, broadband absorption and high absorption capacity of the absorbing material, and has good application prospects in the field of electromagnetic wave absorption.

[0020] 3. The rGO absorbing material prepared by the present invention has excellent absorbing performance due to the structural characteristics of rGO: moderate degree of graphitization, thin layers, porous structure and good dispersion in the matrix, which is also the result of the combined effect of impedance matching, attenuation ability and interference loss.

[0021] 4. The rGO absorbing material prepared by the present invention adjusts the pore size of the graphene oxide aerogel by adjusting the graphene oxide concentration to adjust the complex dielectric constant to meet the impedance matching. At the same time, the interface polarization effect of multiple reflections in the graphene oxide can provide additional dielectric loss capacity, so that the broadband absorption capacity of the synthesized rGO material as an absorbing material is greatly improved compared with the reported absorbing materials, and the absorbing material has not been reported in the field of electromagnetic wave absorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the XRD spectrum of rGO absorbing material.

[0023] Figure 2 It is the SEM image of rGO absorber material.

[0024] Figure 3 This is the full XPS spectrum of rGO absorbing material.

[0025] Figure 4 This is the electromagnetic wave absorption curve of rGO absorbing material. DETAILED DESCRIPTION

[0026] Example 1 Preparation of rGO absorbing material

[0027] The graphene oxide (10 mg / mL) prepared by Hummers and ultrapure water were mixed in a volume ratio of 1:1, ultrasonicated for 2 hours, and stirred evenly for 1 hour to make the mixed solution uniformly dispersed to prepare a graphene oxide suspension (5 mg / mL). Then, it was frozen under liquid nitrogen and freeze-dried at -80°C for 48 hours to prepare GO aerogel. It was placed in a tubular furnace, and argon was passed through for 30 minutes under an argon atmosphere to evacuate the air in the tubular furnace, and micro-reduced at 260°C (at a heating rate of 5°C / min) for 2.5 hours to obtain rGO absorbing material.

[0028] Figure 1 is the XRD spectrum of rGO absorbing material, Figure 1 It can be seen that the absorbing material has only the graphite carbon diffraction peak at 24.7°, indicating that there is no other impurity doping and the crystallinity is poor.

[0029] Figure 2 This is the SEM image of the rGO absorber. Figure 2 It can be seen that the morphology of the absorbing material is a highly wrinkled and loose porous structure.

[0030] Figure 3 This is the full XPS spectrum of rGO absorber material, Figure 3 It can be seen that the absorbing material contains C and O elements.

[0031] Example 2 Performance test of rGO absorbing material

[0032] The method is as follows: This experiment uses a vector network analyzer. 40 mg of sample is dispersed in 360 mg of melted paraffin. After the temperature cools to room temperature, the mixture is pressed into a ring with an inner diameter of 3.04 mm, an outer diameter of 7 mm, and a thickness of 2 to 5 mm. The coaxial fixture is used for testing. The electromagnetic parameters and S parameters of the sample are tested using a vector network analyzer (Agilent 5234A) for calculating the electromagnetic wave absorption parameters.

[0033] Figure 4 is the electromagnetic wave absorption parameter of rGO absorbing material when the filling amount is 10%, Figure 4 It can be seen that the minimum reflection loss is -17.37dB, corresponding to a thickness of 3.6mm and a frequency of 7.16GHz; at the same time, the maximum EAB is 7.98GHz at a thickness of 2.2mm.

Claims

1. A method for preparing a tunable reduced graphene oxide broadband wave absorbing material, characterized in that: The steps include: 1) Mixing graphene oxide GO prepared by Hummers with ultrapure water by ultrasonic stirring to obtain a GO suspension, and freeze-drying to obtain GO aerogel; 2) placing the GO aerogel obtained in step 1) in a tubular furnace, exhausting the air in the tubular furnace by passing argon gas under an argon atmosphere, heating to a certain temperature for micro-reduction, and obtaining an rGO absorbing material.

2. The preparation method according to claim 1, characterized in that: In step 1), the concentration of GO in the GO suspension is 1.25-15 mg / mL.

3. The preparation method according to claim 2, characterized in that: In step 1), the concentration of GO in the GO suspension is 5 mg / mL.

4. The preparation method according to claim 1, characterized in that: In step 1), the freeze drying is performed at -60°C to -80°C for 48 to 96 hours.

5. The preparation method according to claim 4, characterized in that: In step 1), the freeze drying is performed by freezing under liquid nitrogen and freeze drying at -80°C for 48 hours.

6. The preparation method according to claim 1, characterized in that: In step 2), the time of passing argon gas is 30 to 60 minutes.

7. The preparation method according to claim 6, characterized in that: In step 2), the argon gas passing time is 30 minutes.

8. The preparation method according to claim 1, characterized in that: In step 2), the micro-reduction is carried out at a temperature of 180°C to 330°C at a heating rate of 3 to 7°C / min for 0.5 to 4 hours.

9. The preparation method according to claim 8, characterized in that: In step 2), the micro-reduction is performed at 260° C. for 2.5 hours at a heating rate of 5° C. / min.

10. Use of the rGO absorbing material prepared by the preparation method according to any one of claims 1 to 9 in microwave absorption.

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