Graphene hollow nanosphere, preparation method and application
Through liquid plasma technology and magnetic field channel purification method, the complex and cost-effective preparation of graphene hollow nanospheres is solved, and a simple and efficient large-scale preparation of graphene hollow nanospheres is achieved, which is suitable for electromagnetic shielding materials and conductive materials.
Patent Information
- Application Number
- CN202510489262.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-17
- Publication Date
- 2025-07-25
AI Technical Summary
The existing technology is difficult to achieve simple, efficient and low-cost large-scale preparation of graphene hollow nanospheres, and the existing methods and equipment are complex and the raw materials are expensive, making it difficult to achieve large-scale commercial applications.
Liquid plasma technology is used to form a microscopic plasma environment with instantaneous high temperature and high pressure under macroscopic normal temperature conditions. Liquid plasma graphene is prepared through discharge dielectric and discharge parameters, and the bipolar plate is energized to generate magnetic field channels for purification, and finally the graphene hollow nanospheres are formed.
It realizes a simple, efficient and low-cost large-scale preparation of graphene hollow nanospheres without large-scale equipment, low energy consumption and simple preparation process.
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Figure CN120364682A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electrochemical material manufacturing and modification, and particularly to a graphene hollow nanosphere, a preparation method thereof, and an application thereof. Background Art
[0002] Graphene hollow nanospheres have both the singular dielectric and conductive properties of graphene and the large specific surface area and specific volume properties of nanoscale hollow spheres, and have seen significant development in recent years. Graphene nanospheres are usually made by methods such as the template method, self-assembly method, chemical vapor deposition method, chemical oxidation-reduction method, etc. For example, a method for self-assembling graphene hollow nanospheres using lignin-graphene oxide as a matrix is disclosed in the related art. The degree of uniformity of the graphene hollow nanospheres involved in such methods is relatively low. Another example is that some solutions disclose a method for preparing graphene hollow nanospheres by quenching and corroding polymer-coated metal nanoparticles. Such methods require a large number of devices, expensive raw materials, and complex technological processes, making it difficult to achieve large-scale commercial applications. Therefore, how to achieve simple, efficient, and low-cost graphene hollow nanospheres is an important issue for their large-scale application. Summary of the Invention
[0003] This application aims to solve at least one of the technical problems in the related art to some extent. To this end, the purpose of this application is to propose a graphene hollow nanosphere, a preparation method thereof, and an application thereof. In this application, the liquid-phase plasma technology is used to form a microscopic plasma environment with instantaneous high temperature and high pressure under macroscopic normal temperature conditions. Through the discharge medium and discharge parameters provided by this application, the preparation of liquid-phase plasma graphene can be achieved. Then, a magnetic field channel is generated by applying an electric current to the upper and lower opposite bipolar plates to purify the liquid-phase plasma graphene by magnetic field offset, and finally, graphene hollow nanospheres are formed, achieving the purpose of simply, efficiently, and inexpensively preparing graphene hollow nanospheres on a large scale.
[0004] To achieve the above object, according to the first aspect of this application, a preparation method of a graphene hollow nanosphere is proposed, including:
[0005] Preparation of liquid-phase plasma graphene: A reactive metal wire is sheathed with an aluminum oxide ceramic tube and used as the anode and cathode respectively. The anode and the cathode are placed below the liquid level of the electrolyte and a voltage of 15 - 20 kV is applied to generate glow discharge. After the electrolyte is filtered by suction and dried, liquid-phase plasma graphene is obtained.
[0006] Purification of liquid-phase plasma graphene: The liquid-phase plasma graphene is crushed and a magnetic field channel is generated by applying an electric current to the upper and lower opposite bipolar plates.
[0007] Molding of graphene hollow nanospheres: The purified liquid-phase plasma graphene is put into a first mixed solution and stirred for 6 h; then the first mixed solution is filtered by suction, washed, and dried.
[0008] In some embodiments, during the preparation of the liquid-phase plasma graphene, the power source for glow discharge is a dual-pulse glow plasma power source, and its waveform is a square wave.
[0009] In some embodiments, the duty cycle during the preparation of the liquid-phase plasma graphene is 45%-70%.
[0010] In some embodiments, the diameter of the active metal wire is 1.0 mm - 2.5 mm, and its material includes aluminum, iron, zinc or tin metal.
[0011] In some embodiments, the electrolyte includes 200 - 400 mL of benzene solution and 350 - 700 mL of N,N-dimethylformamide.
[0012] In some embodiments, a direct current of 6 - 120 V is applied to both ends of the bipolar plate to generate the magnetic field channel.
[0013] In some embodiments, the liquid-phase plasma graphene is introduced into the magnetic field channel through a blower.
[0014] In some embodiments, the first mixed solution includes 55% - 80% by volume of HCl and 10% - 40% by volume of HNO3.
[0015] According to the second aspect of the present application, a graphene hollow nanosphere is provided, which is prepared by using the method described in any one of the above embodiments, and has a magnetic core-shell structure.
[0016] According to the third aspect of the present application, the graphene hollow nanosphere described in any one of the above embodiments is applied in electromagnetic shielding materials or conductive materials.
[0017] The additional aspects and advantages of the present application will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present application. Description of the Drawings
[0018] The above and / or additional aspects and advantages of the present application will become obvious and easy to understand from the following description of the embodiments in conjunction with the drawings, where:
[0019] Figure 1 is the forming principle diagram of the hollow graphene nanosphere proposed by the present application;
[0020] Figure 2 is the morphology diagram of the hollow graphene nanosphere in Example 1 of the present application;
[0021] Figure 3 is the purification schematic diagram of the liquid-phase plasma graphene proposed by the present application;
[0022] In the figure, 1 is the upper electrode plate; 2 is the lower electrode plate; 3 is the dielectric layer; 4 is the feed inlet; 5 is the separation chamber; 6 is the collection chamber; 7 is the DC power supply; 8 is the graphene hollow nanosphere; 9 is the amorphous carbon. Specific embodiments
[0023] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application. On the contrary, the embodiments of the present application include all changes, modifications, and equivalents that fall within the spirit and scope of the appended claims.
[0024] The examples of the present application will be described in detail below. The examples of the examples are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The examples described below by referring to the drawings are exemplary and are intended to be used to explain the present application and should not be construed as a limitation of the present application.
[0025] As Figure 1 shown, to achieve the above object, according to the first aspect of the present application, a method for preparing graphene hollow nanospheres is proposed, including the following steps:
[0026] S1: Preparation of liquid-phase plasma graphene; an active metal wire is sheathed with an aluminum oxide ceramic tube and used as the anode and cathode respectively. The anode and cathode are placed below the liquid level of the electrolyte and a voltage of 15 - 20 kV is applied to generate glow discharge. After the liquid is filtered by suction and dried, liquid-phase plasma graphene is obtained.
[0027] S2: Purification of liquid-phase plasma graphene; after the liquid-phase plasma graphene is crushed, purification is carried out by generating a magnetic field channel through energizing the upper and lower opposing bipolar plates.
[0028] S3: Molding of graphene hollow nanospheres; the purified liquid-phase plasma graphene is put into the first mixed solution and stirred for 6 h; then the first mixed solution is filtered by suction, washed, and dried.
[0029] Among them, in S1, active metals such as aluminum, iron, zinc, and tin are made into filaments with a diameter of 1.0 mm - 2.5 mm as active metal wires. The diameter of the active metal wires can be 1.0 mm, 1.3 mm, 1.5 mm, 1.7 mm, 2.0 mm, 2.3 mm, or 2.5 mm. For example, in some embodiments, active metals such as aluminum, iron, zinc, and tin are made into filaments with a diameter of 1 mm as active metal wires. The active metal wires are inserted into a pre-prepared alumina ceramic tube with an inner diameter of 1 mm and serve as the anode and cathode in the reactor respectively. In order to facilitate the operation of liquid-phase plasma electrolysis, the anode and cathode can be embedded on both sides of the reactor.
[0030] An electrolyte is added to the reactor. The electrolyte includes 200 - 400 mL of benzene solution and 350 - 700 mL of N,N-dimethylformamide. For example, 200 - 400 mL of Benzene and 350 - 700 mL of DMF (N,N-dimethylformamide) are added to the reactor in sequence. A magnetic stirrer is used to stir at 400 - 1000 rpm for 15 min to prepare the electrolyte, so that the anode and cathode made of the active metal wires are placed below the liquid level of the electrolyte. At this time, the power supply provided to the anode and cathode is a double-pulse glow plasma power supply of 15 - 20 kV. The preferred power supply is 20 kV, the waveform is a square wave, and the duty cycle is 45% - 70%. In some embodiments, the duty cycle can be 65%. After 20 min of treatment, glow discharge occurs. After the discharge ends, the treated black liquid is filtered by an oil-phase filter membrane and dried in an incubator at 65°C for 24 h to obtain liquid-phase plasma graphene. The preparation principle of the liquid-phase plasma graphene using liquid-phase plasma discharge is as shown in Figure 1 Figure a of
[0031] Among them, in S2, the liquid-phase plasma graphene obtained in S1 is purified. The liquid-phase plasma graphene obtained in S1 is ground into powder with a mortar. There is a certain distance between the upper and lower opposite bipolar plates. By connecting a direct current of 6 - 120 V to both ends of the bipolar plates, a magnetic field channel is formed in the channel between the bipolar plates, and the liquid-phase plasma graphene passes through the magnetic field channel to achieve purification.
[0032] For example, the pulverized liquid-phase plasma graphene is placed on one side of the magnetic field channel in the left-right direction, and a blower is placed at the rear end of the liquid-phase plasma graphene. The liquid-phase plasma graphene is introduced into the magnetic field channel through the feed port 4, introduced from one end of the magnetic field channel, and flows out from the other end of the magnetic field channel. After the liquid-phase plasma graphene flows out of the magnetic field channel, it can be collected to achieve the purification of the liquid-phase plasma graphene.
[0033] For example, as shown in Figure 3As shown, in the separation chamber 5 with a volume, an upper electrode plate 1 and a lower electrode plate 2 are respectively arranged at its top and bottom. An inlet 4 is opened at one end of the separation chamber 5, and a collection chamber 6 communicating with the separation chamber 5 is arranged at the other end. The upper electrode plate 1 and the lower electrode plate 2 are oppositely arranged in the up and down direction, and there is a spacing between the two in the up and down direction to form a channel for the flow of liquid-phase plasma graphene. A dielectric layer 3 is arranged on the lower surface of the upper electrode plate 1. By connecting a DC power supply 7 of 6 - 120V to both ends of the bipolar plate formed by the upper electrode plate 1 and the lower electrode plate 2, a magnetic field channel is formed in the channel between the upper electrode plate 1 and the lower electrode plate 2. The pulverized liquid-phase plasma graphene is placed at the inlet 4, and a blower is placed at the rear end of the liquid-phase plasma graphene. The blower is used to introduce the liquid-phase plasma graphene into the magnetic field channel through the inlet 4. Finally, the liquid-phase plasma graphene in the collection chamber 6 at the other end of the magnetic field channel is collected by a filter membrane, realizing the purification of the liquid-phase plasma graphene, and the amorphous carbon 9 separated out remains in the separation chamber 5.
[0034] Among them, in S3, the liquid-phase plasma graphene purified in S2 is put into a first mixed solution formed by mixing HCl with a volume percentage of 55% - 80% and HNO3 with a volume percentage of 10% - 40% and stirred. In some embodiments, the first mixed solution includes HCl with a volume percentage of 75% and HNO3 with a volume percentage of 25%. The liquid-phase plasma graphene purified in S2 is stirred in the first mixed solution for 6h, then the first mixed solution is filtered by a water-phase filter membrane, and the solidified product is rinsed with excessive deionized water. The solidified product is dried in an incubator at 50°C for 24h to obtain graphene hollow nanospheres 8. The schematic diagram of the formation principle of the hollow graphene nanospheres is as Figure 1 shown in Figure b of Figure 2 which, and the morphology diagram of the graphene hollow nanospheres is as
[0035] In this embodiment, liquid-phase plasma graphene is prepared by liquid-phase plasma discharge, which can be rapidly obtained at room temperature with simple and easily available raw materials. At the same time, a bipolar plate arranged oppositely up and down is designed to generate a magnetic field channel by electrifying, and the liquid-phase plasma graphene is subjected to magnetic field offset purification through the magnetic field channel, which can effectively filter out the mixed amorphous carbon and improve the purity of the prepared liquid-phase plasma graphene. Finally, the formation of graphene hollow nanospheres is realized. The method provided by this application can be obtained in conventional experiments, without large-scale equipment and with low energy consumption.
[0036] According to the second aspect of this application, a graphene hollow nanosphere is proposed, which is prepared by using the method in any of the above embodiments and has a magnetic core-shell structure.
[0037] According to the third aspect of this application, the graphene hollow nanospheres in any of the above embodiments are applied in electromagnetic shielding materials or conductive materials.
[0038] Example 1
[0039] Tin was made into filaments with a diameter of 1 mm and inserted into pre-prepared alumina ceramic tubes with an inner diameter of 1 mm, which were used as the anode and cathode in the reactor respectively and embedded on both sides of the reactor. 400 mL of benzene solution and 350 mL of DMF were successively added to the reactor, and a magnetic stirrer was used to stir at 500 rpm for 15 min to prepare the electrolyte, so that the tin filaments were placed below the liquid level of the electrolyte. The power supply provided to the anode and cathode was a 20 kV double-pulse glow plasma power supply, with a square wave waveform and a duty cycle of 65%; after 20 min of treatment to generate glow discharge, after the discharge ended, the treated black liquid was filtered by an oil-phase filter membrane and dried in an oven at 65 °C for 24 h to obtain liquid-phase plasma graphene.
[0040] The obtained liquid-phase plasma graphene was ground into powder with a mortar, and a magnetic field channel was generated by connecting a 120 V DC power supply to the upper and lower bipolar plates; the crushed liquid-phase plasma graphene was placed at the feed port 4 and blown through the magnetic field channel by a blower, and the liquid-phase plasma graphene flowing out of the magnetic field channel was collected by a filter membrane to complete the purification as Figure 3 shown.
[0041] The purified liquid-phase plasma graphene was put into a first mixed solution formed by mixing 75% by volume of HCl and 25% by volume of HNO3 and stirred for 6 h. Then the first mixed solution was filtered by a water-phase filter membrane, and the solidified product was rinsed with excessive deionized water. The solidified product was dried in an oven at 50 °C for 24 h to obtain graphene hollow nanospheres.
[0042] Example 2
[0043] Iron was made into filaments with a diameter of 1 mm and inserted into pre-prepared alumina ceramic tubes with an inner diameter of 1 mm, which were used as the anode and cathode in the reactor respectively and embedded on both sides of the reactor. 200 mL of benzene solution and 550 mL of DMF were successively added to the reactor, and a magnetic stirrer was used to stir at 1000 rpm for 15 min to prepare the electrolyte, so that the iron filaments were placed below the liquid level of the electrolyte. The power supply provided to the anode and cathode was a 20 kV double-pulse glow plasma power supply, with a square wave waveform and a duty cycle of 65%; after 20 min of treatment to generate glow discharge, after the discharge ended, the treated black liquid was filtered by an oil-phase filter membrane and dried in an oven at 65 °C for 24 h to obtain liquid-phase plasma graphene.
[0044] The obtained liquid-phase plasma graphene is ground into powder with a mortar, and a magnetic field channel is generated by connecting a 100V DC power supply to the upper and lower opposing bipolar plates; the pulverized liquid-phase plasma graphene is placed at the feed inlet 4 and passed through the magnetic field channel under the blowing of a blower, and the liquid-phase plasma graphene flowing out of the magnetic field channel is collected by a filter membrane to complete purification.
[0045] The purified liquid-phase plasma graphene is put into a first mixed solution formed by mixing 75% by volume of HCl and 25% by volume of HNO3 and stirred for 6 h. Then, the first mixed solution is filtered by a water-phase filter membrane, and the solidified product is rinsed with excessive deionized water. The solidified product is dried in an incubator at 50 °C for 24 h to obtain graphene hollow nanospheres.
[0046] Example 3
[0047] Zinc is made into a wire with a diameter of 2 mm and inserted into a pre-prepared alumina ceramic tube with an inner diameter of 1 mm, which are used as the anode and cathode in the reactor respectively and embedded on both sides of the reactor. 300 mL of benzene solution and 450 mL of DMF are successively added to the reactor, and a magnetic stirrer is used to stir at 800 rpm for 15 min to prepare an electrolyte solution, so that the zinc wire is placed below the liquid level of the electrolyte solution. The power supply provided to the anode and cathode is a 15 kV bipolar pulse glow plasma power supply, the waveform is a square wave, and the duty cycle is 65%; after 20 min of treatment to generate glow discharge, after the discharge ends, the treated black liquid is filtered by an oil-phase filter membrane and dried in an incubator at 65 °C for 24 h to obtain liquid-phase plasma graphene.
[0048] The obtained liquid-phase plasma graphene is ground into powder with a mortar, and a magnetic field channel is generated by connecting a 120V DC power supply to the upper and lower opposing bipolar plates; the pulverized liquid-phase plasma graphene is placed at the feed inlet 4 and passed through the magnetic field channel under the blowing of a blower, and the liquid-phase plasma graphene flowing out of the magnetic field channel is collected by a filter membrane to complete purification.
[0049] The purified liquid-phase plasma graphene is put into a first mixed solution formed by mixing 75% by volume of HCl and 25% by volume of HNO3 and stirred for 6 h. Then, the first mixed solution is filtered by a water-phase filter membrane, and the solidified product is rinsed with excessive deionized water. The solidified product is dried in an incubator at 50 °C for 24 h to obtain graphene hollow nanospheres.
[0050] Example 4
[0051] Aluminum was made into fine wires with a diameter of 2.5 mm and inserted into pre-prepared alumina ceramic tubes with an inner diameter of 1 mm, serving as the anode and cathode in the reactor respectively and embedded on both sides of the reactor. 300 mL of benzene solution and 700 mL of DMF were successively added to the reactor, and a magnetic stirrer was used to stir at 600 rpm for 15 min to prepare an electrolyte, such that the aluminum wires were placed below the liquid level of the electrolyte. The power supply provided to the anode and cathode was a dual-pulse glow plasma power supply of 18 kV, with a square wave waveform and a duty cycle of 65%; after 20 min of treatment to generate glow discharge, and after the discharge ended, the treated black liquid was filtered by an oil-phase filter membrane and dried in an incubator at 65 °C for 24 h to obtain liquid-phase plasma graphene.
[0052] The obtained liquid-phase plasma graphene was ground into powder with a mortar, and a magnetic field channel was generated by connecting a 20 V DC power supply to the upper and lower opposing bipolar plates; the pulverized liquid-phase plasma graphene was placed at the feed port 4 and blown through the magnetic field channel by a blower, and the liquid-phase plasma graphene flowing out of the magnetic field channel was collected using a filter membrane to complete purification.
[0053] The purified liquid-phase plasma graphene was put into a first mixed solution formed by mixing HCl with a volume percentage of 75% and HNO3 with a volume percentage of 25% and stirred for 6 h. Then, the first mixed solution was filtered by an aqueous-phase filter membrane, and the solidified product was rinsed with an excessive amount of deionized water, and the solidified product was dried in an incubator at 50 °C for 24 h to obtain graphene hollow nanospheres.
[0054] Comparative Example 1
[0055] Platinum was made into fine wires with a diameter of 0.5 mm and inserted into pre-prepared alumina ceramic tubes with an inner diameter of 0.5 mm, serving as the anode and cathode in the reactor respectively and embedded on both sides of the reactor. 50 mL of benzene solution and 750 mL of DMF were successively added to the reactor, and a magnetic stirrer was used to stir at 1500 rpm for 15 min to prepare an electrolyte, such that the platinum electrodes were placed below the liquid level of the electrolyte. The power supply provided to the anode and cathode was a dual-pulse glow plasma power supply of 20 kV, with a square wave waveform and a duty cycle of 40%; after 20 min of treatment to generate glow discharge, and after the discharge ended, the treated black liquid was filtered by an oil-phase filter membrane and dried in an incubator at 65 °C for 24 h to obtain liquid-phase plasma graphene.
[0056] The obtained liquid-phase plasma graphene was ground into powder with a mortar, and a magnetic field channel was generated by connecting a 200 V DC power supply to the upper and lower opposing bipolar plates; the pulverized liquid-phase plasma graphene was placed at the feed port 4 and blown through the magnetic field channel by a blower, and the liquid-phase plasma graphene flowing out of the magnetic field channel was collected using a filter membrane to complete purification as Figure 3 shown.
[0057] The purified liquid-phase plasma graphene is put into a first mixed solution formed by mixing HCl with a volume percentage of 15% and HNO3 with a volume percentage of 85% and stirred for 6 h. Then, the first mixed solution is filtered by a water-phase filter membrane, and the solidified product is rinsed with excessive deionized water. The solidified product is dried in an incubator at 50 °C for 24 h. The obtained material is amorphous carbon with a low porosity rate.
[0058] It should be noted that in the description of the present application, the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. In addition, in the description of the present application, unless otherwise specified, the meaning of "a plurality" is two or more.
[0059] Any process or method description shown in the flowchart or described in other ways herein can be understood to represent a module, segment, or part of code including one or more executable instructions for implementing a specific logical function or process. The scope of the preferred embodiments of the present application includes additional implementations, where the functions may be executed in a substantially simultaneous manner or in a reverse order according to the functions involved, rather than in the order shown or discussed. This should be understood by those skilled in the technical field of the embodiments of the present application.
[0060] In the description of this specification, the descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.
[0061] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.
Claims
1. A preparation method of graphene hollow nanospheres, characterized in that, Including Preparation of liquid-phase plasma graphene: After a reactive metal wire is sheathed with an alumina ceramic tube, it is used as the anode and the cathode respectively. The anode and the cathode are placed below the liquid level of the electrolyte and a voltage of 15 - 20 kV is applied to generate glow discharge. After the electrolyte is filtered by suction and dried, liquid-phase plasma graphene is obtained. Purification of liquid-phase plasma graphene: The liquid-phase plasma graphene is crushed and a magnetic field channel is generated by applying direct current to the upper and lower bipolar plates facing each other. Molding of graphene hollow nanospheres: The purified liquid-phase plasma graphene is put into the first mixed solution and stirred for 6 h; then the first mixed solution is filtered by suction, washed, and dried.
2. The preparation method according to claim 1, characterized in that, During the preparation process of the liquid-phase plasma graphene, the power supply for glow discharge is a bipolar pulse glow plasma power supply, and its waveform is a square wave.
3. The preparation method according to claim 2, characterized in that, During the preparation process of the liquid-phase plasma graphene, the duty cycle is 45% - 70%.
4. The preparation method according to any one of claims 1-3, characterized in that, The diameter of the reactive metal wire is 1.0 mm - 2.5 mm, and its material includes metals such as aluminum, iron, zinc, or tin.
5. The preparation method according to claim 4, wherein The electrolyte includes 200 - 400 mL of benzene solution and 350 - 700 mL of N,N-dimethylformamide.
6. The preparation method according to claim 4, characterized in that, A direct current of 6 - 120 V is applied to both ends of the bipolar plate to generate the magnetic field channel.
7. The preparation method according to claim 6, characterized in that, The liquid-phase plasma graphene is introduced into the magnetic field channel through a blower.
8. The preparation method according to claim 4, characterized in that, The first mixed solution includes HCl with a volume percentage of 55% - 80% and HNO3 with a volume percentage of 10% - 40%.
9. A graphene hollow nanosphere, characterized in that, Prepared by the method according to any one of claims 1 - 8, and it has a magnetic core-shell structure.
10. Application of the graphene hollow nanosphere according to claim 9 in an electromagnetic shielding material or a conductive material.