Graphene oxide tin-coated composite material and preparation method thereof

Abstract

The invention discloses a graphene oxide tin-coated composite material and a preparation method thereof.The graphene oxide tin-coated composite material is prepared from graphene oxide and tin powder, the mass ratio of the graphene oxide to the tin powder is (10-30): 1, and the graphene oxide and the tin powder are combined through spray drying and high-temperature calcination; according to the technical scheme, the tin powder with low conductivity and the graphene oxide with high dielectric constant are compounded, so that the impedance matching performance of the wave-absorbing material and the attenuation performance of the wave-absorbing material on electromagnetic waves are improved.

Description

Technical Field

[0001] The present application relates to the technical field of composite materials containing graphene oxide, and in particular to a graphene oxide-tin-coated composite material and a preparation method thereof. Background Art

[0002] Graphene is a two-dimensional carbon nanostructured material with a stable structure, low density, high specific surface area and excellent conductivity. The layered structure of graphene can enhance electromagnetic interaction, thereby achieving strong dielectric loss and polarization loss. It has the potential to become a high-quality microwave absorption material, but due to poor impedance matching, the practical application of graphene-based absorbing materials is limited.

[0003] Graphene oxide's rich surface chemical activity makes it easy to mix with other magnetic and dielectric materials, balancing the absorber's electromagnetic loss and impedance matching capabilities. Selecting non-magnetic metal materials with significantly different electrical conductivity from carbon materials to prepare composite materials can adjust the composite's dielectric constant, achieve better impedance matching, and further enhance microwave absorption performance.

[0004] The use of ferromagnetic materials and graphene oxide for compounding can, on the one hand, construct a heterogeneous interface to enhance the interface polarization loss and improve the impedance matching performance of graphene-based materials; on the other hand, the magnetic loss performance of the ferromagnetic material itself can further enhance the magnetic loss capacity of the composite material; although the composite of ferromagnetic materials and graphene can effectively improve the performance of absorbing materials, there are fewer reports on the use of non-magnetic metal materials with electrical conductivity that is significantly different from that of carbon materials for the preparation of absorbing materials. Therefore, how to effectively screen out such non-magnetic metal materials and graphene oxide for compounding to prepare a new type of absorbing material to achieve the adjustment of the dielectric constant of the composite material, obtain better impedance matching, and improve the microwave absorption performance has become one of the technical problems to be solved in this field. Summary of the Invention

[0005] In response to the above-mentioned deficiencies in the prior art, the present application provides a graphene oxide-tin composite material that combines low-conductivity tin powder with high-dielectric-constant graphene oxide to improve the impedance matching performance and electromagnetic wave attenuation performance of the absorbing material.

[0006] In order to solve the above technical problems, the technical solution adopted in this application is: a graphene oxide-tin composite material, the raw materials for preparing the composite material include: graphene oxide and tin powder, wherein the mass ratio of the graphene oxide to the tin powder is (10-30):1, and the graphene oxide and the tin powder are combined with each other through spray drying and high-temperature calcination.

[0007] Furthermore, the particle size of the tin powder is 150-250 mesh.

[0008] The present application also provides a method for preparing a graphene oxide-tin composite material, comprising:

[0009] (1) Weighing graphene oxide powder and adding it to an ethanol solution, ultrasonicating at room temperature until the graphene oxide is completely dissolved, then adding deionized water and adjusting the pH to neutral to obtain an aqueous dispersion of graphene oxide, then adding tin powder, stirring and dispersing it uniformly to obtain a mixed solution;

[0010] (2) atomizing the mixed solution prepared in step (1) above through a nozzle of a spray dryer, and carrying the mixed solution through a cyclone separator with preheated air to fold and shrink the graphene oxide sheets, thereby wrapping the tin powder, and obtaining a precursor powder after cooling;

[0011] (3) The precursor powder is placed in a nitrogen atmosphere, heated to 450-650°C at a heating rate of 3-6°C / min, and calcined for 3-6 hours. After cooling naturally, the prepared graphene oxide-coated tin composite material is obtained.

[0012] Furthermore, the concentration of graphene oxide powder in the graphene oxide aqueous dispersion in step (1) is 0.5-3 wt%.

[0013] Furthermore, the mass ratio of graphene oxide to tin powder in step (1) is (10-30):1.

[0014] Furthermore, the particle size of the tin powder in step (1) is 150-250 mesh.

[0015] Furthermore, the nozzle atomization pressure in step (2) is 0.1-0.3 MPa.

[0016] Furthermore, the temperature of the preheated air in step (2) is 130-160°C.

[0017] Furthermore, the temperature of the preheated air in step (2) is 135-145°C.

[0018] Furthermore, in step (2), the temperature is raised to 500-550° C. at a heating rate of 4-5° C. / min, and the calcination time is 4-5 h.

[0019] Advantages and beneficial effects of this application:

[0020] 1. This application uses tin powder and graphene oxide to composite materials, mainly using non-magnetic metal materials with conductivity that is significantly different from that of carbon materials to prepare composite materials. This combination method can adjust the dielectric constant of the composite material, achieve better impedance matching, and thus further improve the microwave absorption performance; this application composites low-conductivity tin powder with high-dielectric-constant graphene oxide to improve the impedance matching performance and electromagnetic wave attenuation performance of the graphene-based absorbing material. The unique capacitance structure and conductive network of the graphene oxide-wrapped tin composite material give it strong dielectric loss and excellent absorption performance.

[0021] 2. In this application, graphene oxide and tin powder are first dispersed in an aqueous solvent by stirring or ultrasound to obtain a mixed solution, and then the solvent water molecules are rapidly evaporated under high temperature and high pressure by spray drying. During the rapid shrinkage of the graphene oxide, the tin powder is simultaneously wrapped. Finally, the composite material is calcined at high temperature to improve the structural stability of the composite material.

[0022] 3. The graphene oxide-tin composite material prepared by the spray drying method in the present application is simple and easy to prepare. It can completely wrap the tin powder with the graphene oxide nanosheets while avoiding the stacking of the graphene oxide nanosheets and the agglomeration of the tin powder particles. The reflection loss can reach up to -32.99 dB at a high frequency of 11.14 GHz, and it has excellent absorbing performance. After the tin powder, which has a large difference in electrical conductivity from graphene oxide, is compounded with graphene oxide, the absorbing performance of the composite absorbing material is improved. By adjusting the dosage ratio of the tin powder, the composite absorbing material can achieve excellent absorbing performance at higher frequency bands. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The graphene oxide tin-coated composite material prepared in Example 1 ( Figure 1 -a) and tin powder ( Figure 1 -b) SEM image.

[0024] Figure 2 The real part of the complex dielectric constant ε'( Figure 2 -a)、imaginary part ε"( Figure 2 -b) and dielectric loss tangent tanδ ε ( Figure 2 -c) Comparison chart of changes with frequency.

[0025] Figure 3 This is the SEM image of the graphene oxide tin composite material prepared by the hydrothermal method in Comparative Example 2. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of this application in conjunction with the embodiments and drawings. Obviously, the embodiments described are only preferred embodiments, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0027] Example 1:

[0028] A graphene oxide tin-coated composite material and a preparation method thereof, wherein the specific implementation steps are as follows:

[0029] (1) Weigh 5 g of graphene oxide powder and add it to 100 mL of ethanol solution. Ultrasonicate at room temperature until GO is completely dissolved. Then add 400 mL of deionized water and adjust the pH to neutral to obtain an aqueous dispersion of graphene oxide. Then, add 0.25 g of tin powder and stir until uniformly dispersed to obtain a mixed solution.

[0030] The concentration of the graphene oxide aqueous dispersion is 1 wt %, and the mass ratio of graphene oxide to tin powder is 20:1.

[0031] (2) The mixed liquid obtained above is atomized through a nozzle at a pressure of 0.2 MPa, and is carried by preheated air (140°C) through a cyclone separator (a cyclone separator is a component of a spray drying device. The mixed liquid is sprayed from the spray nozzle, and the atomized raw material enters the drying chamber and contacts with hot air. After drying, the product is obtained. The product passes through the cyclone separator driven by the flowing preheated air, and the product enters the product collection bottle through the lower end of the cyclone separator, and the flowing hot air is discharged from the upper end of the cyclone separator), so that the GO sheet folds and shrinks, thereby wrapping the tin powder, and the precursor powder is obtained after cooling;

[0032] (3) The precursor powder was placed in a nitrogen atmosphere, heated to 550°C at a heating rate of 4°C / min, and calcined for 4 hours. After cooling naturally, the prepared graphene oxide-coated tin composite material was obtained.

[0033] Comparative Example 1

[0034] The difference between Comparative Example 1 and Example 1 is that in step (1), tin powder is not added, that is, only the graphene oxide aqueous dispersion is spray-dried, and the rest of the processes are exactly the same.

[0035] Figure 1 The graphene oxide tin composite material prepared in Example 1 ( Figure 1 -a) and tin powder ( Figure 1 -b) SEM image. As can be seen from the figure, a spherical core-shell composite material of carbonyl iron powder wrapped in graphene oxide can be obtained by spray drying.

[0036] The graphene oxide-tin composite material prepared in Example 1 and the wrinkled graphene oxide prepared in Comparative Example 1 were added to molten paraffin, molded into cylinders and cylindrical rings, respectively, for conductivity testing and microwave absorption (MA) measurement, respectively. Figure 2 The real part of the complex dielectric constant ε'( Figure 2 -a)、imaginary part ε"( Figure 2 -b) and dielectric loss tangent tanδ ε ( Figure 2 -c) Comparison of the change with frequency. The real part of the dielectric constant ε' is related to energy storage, and the imaginary part ε" is also called the loss factor, which indicates the loss capacity of the composite material to electromagnetic waves. The dielectric loss tangent (tanδ e =ε" / ε') is a key parameter for evaluating the dielectric loss capacity of microwave absorbers. Materials with a high loss tangent can effectively absorb microwaves and convert them into other energy. As can be seen from the figure, the complex dielectric constant and loss tangent of the graphene oxide-tin composite material increase after tin powder is combined with graphene oxide nanosheets, indicating that it has a better electromagnetic wave loss capacity.

[0037] Examples 1 to 3 illustrate the effect of graphene oxide and tin powder compounded in different proportions on the microwave absorbing properties of the composite material.

[0038] Example 2:

[0039] A graphene oxide tin-coated composite material and a preparation method thereof, wherein the specific implementation steps are as follows:

[0040] (1) Weigh 5 g of graphene oxide powder and add it to 100 mL of ethanol solution. Ultrasonicate at room temperature until GO is completely dissolved. Then add 400 mL of deionized water and adjust the pH to neutral to obtain an aqueous dispersion of graphene oxide. Then add 0.5 g of tin powder and stir until uniformly dispersed to obtain a mixed solution.

[0041] The concentration of the graphene oxide aqueous dispersion is 1 wt %, and the mass ratio of graphene oxide to tin powder is 10:1.

[0042] (2) The mixture was atomized through a nozzle at a pressure of 0.2 MPa and carried through a cyclone separator by preheated air (140°C), causing the GO sheets to fold and shrink, thereby wrapping the tin powder. After cooling, the precursor powder was obtained;

[0043] (3) The precursor powder was placed in a nitrogen atmosphere, heated to 550°C at a heating rate of 4°C / min, and calcined for 4 hours. After cooling naturally, the prepared graphene oxide-coated tin composite material was obtained.

[0044] Example 3:

[0045] A graphene oxide tin-coated composite material and a preparation method thereof, wherein the specific implementation steps are as follows:

[0046] (1) Weigh 5 g of graphene oxide powder and add it to 100 mL of ethanol solution. Ultrasonicate at room temperature until GO is completely dissolved. Then add 400 mL of deionized water and adjust the pH to neutral to obtain an aqueous dispersion of graphene oxide. Then, add (1 / 6) g of tin powder, stir and disperse evenly to obtain a mixed solution.

[0047] The concentration of the graphene oxide aqueous dispersion is 1 wt %, and the mass ratio of graphene oxide to tin powder is approximately 30:1.

[0048] (2) The mixture was atomized through a nozzle at a pressure of 0.2 MPa and carried through a cyclone separator by preheated air (140°C), causing the GO sheets to fold and shrink, thereby wrapping the tin powder. After cooling, the precursor powder was obtained;

[0049] (3) The precursor powder was placed in a nitrogen atmosphere, heated to 550°C at a heating rate of 4°C / min, and calcined for 4 hours. After cooling naturally, the prepared graphene oxide-coated tin composite material was obtained.

[0050] To illustrate the advantages of preparing graphene oxide-tin composite materials by spray drying, the graphene oxide-tin composite materials prepared by spray drying in Example 1 were compared with the graphene oxide-tin composite materials prepared by hydrothermal method in Comparative Example 2.

[0051] Comparative Example 2

[0052] The graphene oxide-coated tin composite material is prepared by hydrothermal reaction, and the specific implementation steps are as follows:

[0053] (1) Preparation of a mixed solution: 5 g of graphene oxide powder was weighed and added to 100 mL of ethanol solution. The mixture was ultrasonicated at room temperature until the GO was completely dissolved. 400 mL of deionized water was then added and the pH was adjusted to neutral to obtain an aqueous dispersion of graphene oxide. 0.25 g of tin powder was then added and stirred to disperse the mixture evenly to obtain a mixed solution.

[0054] The concentration of the graphene oxide aqueous dispersion is 1 wt %, and the mass ratio of graphene oxide to tin powder is 20:1.

[0055] (2) The mixed solution was placed in a polytetrafluoroethylene liner and kept at 150°C for 3 hours. After cooling to room temperature, the solid was transferred to a beaker, quickly frozen into blocks, and freeze-dried for 48 hours to obtain a precursor powder.

[0056] (3) Calcination process: The precursor powder is placed in an argon protective atmosphere, heated to 550°C at a heating rate of 4°C / min, and calcined for 4 hours. After natural cooling, the prepared graphene oxide-coated tin composite material is obtained.

[0057] Figure 3 The SEM image of the graphene oxide tin composite material prepared by the hydrothermal method in comparative example 2. Figure 3 As can be seen, compared with the graphene oxide-tin composite material prepared by the spray-drying method in Example 1, the graphene oxide-tin composite material prepared by the hydrothermal method in Comparative Example 2 exhibits tin powder agglomeration, and the graphene oxide nanosheets are unable to completely encapsulate the tin powder, failing to construct a rich heterogeneous interface to enhance the composite absorber's ability to resist polarization loss of electromagnetic waves. This also demonstrates that the graphene oxide-tin composite material prepared by the spray-drying method in Example 1 is simple and easy to prepare, enabling the graphene oxide nanosheets to completely encapsulate the tin powder while preventing stacking of the graphene oxide nanosheets and agglomeration of the tin powder particles.

[0058] The graphene oxide tin composite materials prepared in Examples 1 to 3 and Comparative Example 2, as well as the wrinkled graphene oxide composite material prepared in Comparative Example 1, were added with molten paraffin wax and molded into cylindrical rings. The electromagnetic properties and absorbing properties of the composite absorbing materials were tested using a 3671 series vector network analyzer. The performance test results are shown in Table 1 below:

[0059] Table 1 Performance test of materials prepared in Examples and Comparative Examples

[0060]

[0061] In summary, the graphene oxide-tin composite material prepared by spray drying in the embodiments of the present invention is a simple and easy-to-implement solution that enables the graphene oxide nanosheets to completely encapsulate the tin powder while preventing stacking of the graphene oxide nanosheets and agglomeration of the tin powder particles. The resulting composite material exhibits excellent absorption performance, achieving a maximum reflection loss of -32.99 dB at a high frequency of 11.14 GHz. When tin powder, which has a significantly different conductivity from graphene oxide, is combined with graphene oxide, the composite absorber exhibits enhanced absorption performance. By adjusting the tin powder ratio, the composite absorber can achieve excellent absorption performance at higher frequencies.

Claims

1. A graphene oxide tin-coated composite material, characterized in that: The raw materials for preparing the composite material include: graphene oxide and tin powder, wherein the mass ratio of the graphene oxide to the tin powder is (10-30):1, and the graphene oxide and the tin powder are combined with each other through spray drying and high-temperature calcination.

2. The graphene oxide tin-coated composite material according to claim 1, wherein: The particle size of the tin powder is 150-250 meshes.

3. A method for preparing the graphene oxide-tin composite material according to any one of claims 1-2, characterized in that: include: (1) Weighing graphene oxide powder and adding it to an ethanol solution, ultrasonicating at room temperature until the graphene oxide is completely dissolved, then adding deionized water and adjusting the pH to neutral to obtain an aqueous dispersion of graphene oxide, then adding tin powder, stirring and dispersing it uniformly to obtain a mixed solution; (2) atomizing the obtained mixed solution through the nozzle of a spray dryer, and carrying it through a cyclone separator with preheated air to fold and shrink the graphene oxide sheets, thereby wrapping the tin powder, and obtaining a precursor powder after cooling; (3) The precursor powder is placed in a nitrogen atmosphere, heated to 450-650°C at a heating rate of 3-6°C / min, and calcined for 3-6 hours. After cooling naturally, the prepared graphene oxide-coated tin composite material is obtained.

4. The method for preparing the graphene oxide tin-coated composite material according to claim 3, wherein: The concentration of graphene oxide powder in the graphene oxide aqueous dispersion described in step (1) is 0.5-3wt%.

5. The method for preparing the graphene oxide tin-coated composite material according to claim 3, wherein: The mass ratio of graphene oxide to tin powder described in step (1) is (10-30):

1.

6. The method for preparing the graphene oxide tin-coated composite material according to claim 3, wherein: The particle size of the tin powder in step (1) is 150-250 mesh.

7. The method for preparing the graphene oxide tin-coated composite material according to claim 3, wherein: The pressure of the nozzle atomization described in step (2) is 0.1-0.3 MPa.

8. The method for preparing the graphene oxide tin-coated composite material according to claim 3, wherein: The temperature of the preheated air in step (2) is 130-160°C.

9. The method for preparing the graphene oxide tin-coated composite material according to claim 8, wherein: The temperature of the preheated air in step (2) is 135-145°C.

10. The method for preparing the graphene oxide-tin composite material according to claim 3, wherein: In step (2), the temperature is raised to 500-550° C. at a heating rate of 4-5° C. / min, and the calcination time is 4-5 h.

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