CN114314567B - Graphene material and preparation method and application thereof - Google Patents
Graphene material and preparation method and application thereof Download PDFInfo
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- CN114314567B CN114314567B CN202111537364.XA CN202111537364A CN114314567B CN 114314567 B CN114314567 B CN 114314567B CN 202111537364 A CN202111537364 A CN 202111537364A CN 114314567 B CN114314567 B CN 114314567B
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Abstract
The invention discloses a graphene material and a preparation method and application thereof, wherein the graphene material comprises the following components: the graphene comprises at least two graphene layers, wherein a cavity is formed between every two adjacent graphene layers; the graphene ball structure comprises spherical graphene, wherein the spherical graphene is positioned in a cavity between two adjacent graphene layers, and the spherical graphene is in a hollow sphere shape. The graphene material disclosed by the invention has a layered cavity and a spherical cavity, and the multi-cavity structure enables the material to have excellent dielectric loss performance, so that the graphene material can be applied to the field of electromagnetic shielding. The dielectric loss value of the graphene material is as high as 2860, the dielectric loss tangent is as high as 25, and the electromagnetic wave can be rapidly converted into heat in a high proportion and dissipated.
Description
Technical Field
The invention belongs to the technical field of materials, and particularly relates to a graphene material as well as a preparation method and application thereof.
Background
Graphene has excellent performances such as low density, high chemical stability, high conductivity, high thermal conductivity coefficient and the like, and has good application prospects in various industries, but at present, high-quality graphene is difficult to prepare, ultra-high-temperature equipment such as a laser, a CVD furnace, a graphitization furnace and the like is often required to be used, a large amount of energy is required to be consumed during preparation, so that the preparation cost is greatly increased, complicated steps are often required for preparing graphene with special morphology (morphology except lamella), and the graphene is difficult to popularize and apply in large batch, so that the development and application of graphene materials are greatly hindered. With the rapid development of the fields of 5G, the Internet of things and the like, the world of everything interconnection comes. Precision and interference-free operation between electronic devices have put higher demands on electromagnetic shielding materials. Therefore, the preparation of materials with low thickness, high dielectric dissipation and high electromagnetic shielding performance is very urgent and necessary.
Disclosure of Invention
In order to overcome the problems of the prior art, an object of the present invention is to provide a graphene material.
The second purpose of the present invention is to provide a method for preparing a graphene material.
The invention further aims to provide an application of the graphene material in an electromagnetic shielding material.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the invention provides a graphene material in a first aspect, which comprises:
the graphene comprises at least two graphene layers, wherein a cavity is formed between every two adjacent graphene layers;
the graphene ball structure comprises spherical graphene, wherein the spherical graphene is located in a cavity between two adjacent graphene layers, and the spherical graphene has a hollow structure.
Preferably, the thickness of the graphene material is 0.5-500um; further preferably, the thickness of the graphene material is 2-200 um; still further preferably, the thickness of the graphene material is 2-100 um; still more preferably, the thickness of the graphene material is 2 to 50um, and more preferably, the thickness of the graphene material is 6um. The graphene material with the thickness of 6um can realize the electromagnetic shielding performance of more than 20dB, and the commercial application performance can be sufficiently met. Too thick or too thin a thickness of the graphene material may cause the obtained graphene material to be broken into small pieces, which cannot be used as an electromagnetic shielding material.
Preferably, the particle size of the spherical graphene is 30-530nm; further preferably, the particle size of the spherical graphene is 50-200 nm; still more preferably, the spherical graphene has a particle size of 50 to 150nm.
Preferably, the shell thickness of the spherical graphene is 1-50 nm; further preferably, the shell thickness of the spherical graphene is 1-30 nm; still more preferably, the shell thickness of the graphene is 5 to 20nm.
Preferably, the graphene material is a three-dimensional continuous material. The three-dimensional continuity is that atoms are connected on a three-dimensional structure, and one surface is not completely disconnected.
The second aspect of the present invention provides a method for preparing a graphene material provided in the first aspect of the present invention, comprising the following steps:
preparing polymer-coated metal nanoparticles;
mixing graphene oxide and polymer-coated metal nanoparticles for reaction, and quenching a reacted solid product;
and etching the quenched product to obtain the graphene material.
Preferably, the etching-quenched product is a product obtained by etching and quenching with an acid solution or an alkali solution, and the metal nanoparticles are removed.
Preferably, the acid solution is: at least one of hydrochloric acid, sulfuric acid and hydroiodic acid; further preferably, the acid solution is hydroiodic acid. The iodine-doped hollow graphene nanospheres can be realized by adopting hydroiodic acid, so that the performance of the material is further improved.
Preferably, the step of mixing and reacting the graphene oxide and the polymer-coated metal nanoparticles is to mix the graphene oxide and the polymer-coated metal nanoparticles in a solvent and perform suction filtration.
Preferably, the solvent is an aqueous solution.
Preferably, the step of preparing the polymer-coated metal nanoparticles specifically comprises: and (3) in-situ polymerizing the carbon source on the surface of the metal nano-particles. The invention utilizes an in-situ polymerization method to prepare the polymer-coated metal nano particles, thereby realizing the insertion of the hollow spherical graphene between graphene layers and realizing the preparation of the multi-cavity three-dimensional continuous graphene material. Since the spherical graphene is prepared in situ, the spherical graphene has good continuity with the graphene layer. The graphene material prepared by the invention has various nano cavity structures (a hollow spherical cavity and a layered cavity between sheet graphene layers), has good dielectric dissipation performance, and can be used as an electromagnetic shielding material.
Preferably, the carbon source further contains at least one of nitrogen, sulfur and phosphorus atoms; further preferably, the carbon source is preferably a polymerized monomer containing a benzene ring. The carbon source in the invention contains at least one of nitrogen, sulfur and phosphorus atoms, so that the prepared graphene nanospheres can be doped, and the performance and defect sites of the graphene nanospheres are improved.
Preferably, the carbon source is selected from at least one of styrene and dopamine hydrochloride.
Preferably, the polymer is at least one of polystyrene and polydopamine.
Preferably, the mass ratio of the carbon source to the metal nanoparticles is 1: (2-20); further preferably, the mass ratio of the carbon source to the metal nanoparticles is 1: (5-10).
Preferably, the metal nanoparticles are at least one of iron, cobalt, nickel, gallium, titanium, palladium, platinum and gold; from the aspects of cost and graphene quality, it is further preferable that the metal nanoparticles are at least one of iron, cobalt and nickel; the metal nanoparticles adopted by the invention are all metals with better solid solubility on carbon, so that the carbon source can be polymerized in situ on the surfaces of the metal nanoparticles, and a polymer shell structure with uniform thickness is formed on the surfaces of the metal nanoparticles.
Preferably, the dielectric loss value of the graphene material is 2800-2900.
Preferably, the dielectric loss tangent of the graphene material is 21 to 25.
Preferably, the metal nanoparticles are prepared by the following preparation method: and mixing and reacting a metal source, alkali liquor, hydrazine hydrate and polyvinylpyrrolidone to obtain the metal nano-particles.
Preferably, the alkali liquor is at least one of sodium hydroxide and potassium hydroxide.
Preferably, the metal nanoparticles have a particle size of 30 to 200nm. The smaller the particle size of the metal nanoparticles, the thinner the thickness of the prepared graphene material.
Preferably, the mass ratio of the graphene oxide to the polymer-coated metal nanoparticles is (1. If the mass ratio of the graphene oxide to the polymer-coated metal nanoparticles is not within the range, an ordered structure cannot be formed, and the performance of the prepared graphene material is poor.
Preferably, the quenching conditions are: the temperature rise rate is 1-30 ℃/min, and the temperature is raised to 600-1200 ℃; then the temperature is reduced to 20-30 ℃ at the speed of 5-50 ℃/min.
Preferably, the quenching temperature is 600-1200 ℃; further preferably, the quenching temperature is 800-1200 ℃; still more preferably, the quenching temperature is 1000 to 1200 ℃. The quenching temperature needs to be below the melting point of the metal nanoparticles, and the higher the temperature is, the higher the quality of the prepared graphene material is.
Preferably, the heating rate during quenching is 5-20 ℃/min; further preferably, the temperature rise rate during quenching is 9 to 11 ℃/min; still more preferably, the temperature increase rate during quenching is 10 ℃/min.
Preferably, the cooling rate during quenching is 10-30 ℃/min; further preferably, the cooling rate during quenching is 15 to 25 ℃/min.
The third aspect of the present invention provides an application of the graphene material provided in the first aspect of the present invention in an electromagnetic shielding material.
The invention has the beneficial effects that: the graphene material disclosed by the invention has a layered cavity and a spherical cavity, and the multi-cavity structure enables the material to have excellent dielectric loss performance, so that the graphene material can be applied to the field of electromagnetic shielding. The dielectric loss value of the graphene material is as high as 2860, the dielectric loss tangent is as high as 25, and the electromagnetic wave can be quickly converted into heat with high proportion and dissipated.
Drawings
FIG. 1 is a schematic flow diagram of the present invention;
FIG. 2 is an SEM image of a cross section of rGO @ rGO material;
FIG. 3 is an SEM image of the surface of rGO @ rGO material;
FIG. 4 is an electromagnetic shielding diagram of rGO @ rGO material;
FIG. 5 is a graph of dielectric constant and permeability for rGO @ rGO materials.
Detailed Description
Specific embodiments of the present invention are described in further detail below with reference to the figures and examples, but the practice and protection of the present invention is not limited thereto. It is noted that the following processes, if not specifically described in detail, are all realizable or understandable by those skilled in the art with reference to the prior art. The reagents or apparatus used are not indicated by the manufacturer, and are regarded as conventional products commercially available.
Example 1
The graphene material in the example is prepared by the following preparation method:
(1) Preparing metallic nickel nanoparticles coated with polydopamine: stirring 0.82g of sodium hydroxide and 16g of hydrazine hydrate at 60 ℃ for 10min, quickly adding 200g of ethylene glycol dissolved with 4.6g of nickel chloride hexahydrate and 7g of PVP (polyvinylpyrrolidone), mechanically stirring at 480 rpm, centrifuging to prepare nickel metal nanoparticles, washing twice with water, ultrasonically dispersing the washed nickel metal nanoparticles in 1000g of water, adding 0.1g of dopamine hydrochloride, adjusting the pH to 8.5-8.8 with a tris solution (trihydroxymethyl aminomethane solution), slowly stirring for 24h, centrifuging, and drying to obtain polydopamine-coated metal nickel nanoparticles with a core-shell structure, wherein the nickel metal nanoparticles are core-shell, the polydopamine is shell, and the particle size of the polydopamine-coated metal nickel nanoparticles is 160nm;
(2) Preparation of graphene material in this example: stirring and mixing graphene oxide and metal nickel nanoparticles (the particle size is 160 nm) coated with polydopamine in an aqueous solution according to the mass ratio of 1. The thickness of the graphene material in the embodiment is 6um, and the particle size of the spherical graphene is 30-530nm; the shell thickness of the spherical graphene is 1-50 nm.
A schematic flow chart of the preparation method of the graphene material in this example is shown in fig. 1.
FIG. 2 is an SEM image of the cross section of rGO @ rGO material, where FIG. 2 (a) is an SEM image of the cross section of the rGO @ rGO material at scale 10 um; FIG. 2 (b) is an SEM image of the cross section of rGO @ rGO material at 300 nm. As can be seen in FIG. 2 (a), the thickness of the rGO @ rGO material prepared in this example was 6um. FIG. 3 is an SEM image of the surface of rGO @ rGO material, where FIG. 3 (a) is an SEM image of the surface of the rGO @ rGO material at scale 10 um; FIG. 3 (b) is an SEM image of the surface of rGO @ rGO material at 300 nm. As can be seen from fig. 2 and 3, the rgo @ rgo material prepared in this example successfully intercalated spherical graphene between graphene layers.
FIG. 4 is an electromagnetic shielding plot of rGO @ rGO material, where the abscissa is the frequency value, the ordinate is the EMI value, SET is the electromagnetic shielding value, SER is the electromagnetic reflection value, SEA is the electromagnetic absorption value, all measured directly by the vector network analyzer using the waveguide method. It can be seen from fig. 4 that the 6um thick rgo @ rgo material has the strongest electromagnetic shielding performance SET =28.6dB at 8.2 GHz. FIG. 5 is a graph of dielectric constant and permeability for an rGO @ rGO material, where e ', e "represents the real and imaginary parts of the material's dielectric constant and u 'and u" represent the real and imaginary parts of the material's permeability, and since the graphene material in the present invention is a dielectric lossy material, only the dielectric constant is of interest. From FIG. 5, it can be seen that the rGO @ rGO material has the maximum dielectric loss value of 2860 at 8.2GHz, which is much larger than the magnetic loss, and the dielectric loss tangent is calculated to be 21-25. Thus, the rgo @ rgo material prepared in this example is an excellent dielectric dissipative material. The electromagnetic shielding performance and the dielectric constant and permeability of the material in this example were measured by the wave guide method using a vector network analyzer, and the dielectric loss tangent was calculated by dividing the imaginary part by the real part of the dielectric constant.
Comparative example 1:
the graphene material in this example was prepared according to the following preparation method:
the graphene oxide was directly filtered by suction, and quenched under the quenching conditions of example 1 to obtain the graphene material of this example, which had a thickness of 7.2um.
The performance of the graphene material in this example was tested, specifically: the electromagnetic shielding value of the graphene material with the thickness of 7.2um in the example is 20dB, which is less than 28.6dB of the graphene material in the example 1; the dielectric loss value of the graphene material in the example is 1000, which is less than 2860 of the graphene material in the example 1; the dielectric loss tangent in this example was 0.98, which is smaller than 21 to 25 of the graphene material in example 1.
Comparative example 2
The graphene material in this example was prepared according to the following preparation method:
directly mixing the graphene oxide and the nickel metal nanoparticles, filtering, and quenching according to the quenching conditions in the example 1 to obtain the graphene material in the example, wherein the thickness of the graphene material is 8.2um.
The performance of the graphene material in this example is tested, specifically: the electromagnetic shielding value of the graphene material with the thickness of 8.2um in the example is 17dB, which is smaller than 28.6dB of the graphene material in the example 1; the dielectric loss value of the graphene material in this example is 700, which is less than 2860 of the graphene material in example 1; the dielectric loss tangent in this example was 0.22, which is smaller than 21 to 25 of the graphene material in example 1.
As can be seen from the comparison of example 1 and comparative examples 1 and 2, the graphene material in the present invention has the layered cavity and the spherical cavity, and the multi-cavity structure enables the material to have excellent dielectric loss performance, so that the dielectric loss value of the graphene material is as high as 2860, the dielectric loss tangent is as high as 25, and the electromagnetic wave can be rapidly converted into heat energy with high proportion and dissipated.
The embodiments of the present invention have been described in detail, but the present invention is not limited to the embodiments, and various changes can be made without departing from the gist of the present invention within the knowledge of those skilled in the art. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.
Claims (9)
1. A graphene material, characterized in that: the method comprises the following steps:
the graphene comprises at least two graphene layers, wherein a cavity is formed between every two adjacent graphene layers;
the graphene ball structure comprises spherical graphene, wherein the spherical graphene is located in a cavity between two adjacent graphene layers, and the spherical graphene has a hollow structure.
2. The graphene material of claim 1, wherein: the thickness of the graphene material is 0.5-500um.
3. The graphene material of claim 1, wherein: the particle size of the spherical graphene is 30-530nm.
4. The graphene material of claim 3, wherein: the shell thickness of the spherical graphene is 1-50 nm.
5. The graphene material according to any one of claims 1 to 4, wherein: the graphene material is a three-dimensional continuous material.
6. The method for producing a graphene material according to any one of claims 1 to 5, wherein: the method comprises the following steps:
preparing polymer-coated metal nanoparticles;
mixing graphene oxide and polymer-coated metal nanoparticles for reaction, and quenching a reacted solid product;
etching the quenched product to obtain the graphene material;
the mass ratio of the graphene oxide to the polymer-coated metal nanoparticles is (1;
the quenching conditions are as follows: the temperature rise rate is 1-30 ℃/min, and the temperature is raised to 600-1200 ℃; then the temperature is reduced to 20-30 ℃ at the speed of 5-50 ℃/min.
7. The method for preparing a graphene material according to claim 6, wherein: the steps for preparing the polymer-coated metal nanoparticles are specifically as follows: and (3) in-situ polymerizing the carbon source on the surface of the metal nano-particles.
8. The method for producing a graphene material according to claim 6, wherein: the particle size of the metal nano-particles is 30-200 nm.
9. Use of the graphene material of any one of claims 1 to 5 in an electromagnetic shielding material.
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