Carbon microspheres, their preparation methods and applications

Abstract

This application discloses carbon microspheres, their preparation method, and applications. The method for preparing carbon microspheres includes: forming a liquid metal layer on one side of a carbon substrate; performing a first microwave plasma chemical vapor deposition (IPV) treatment on the side of the carbon substrate with the liquid metal layer, raising the temperature of the carbon substrate to an etching temperature to obtain a carbon substrate with an etched surface; the first gas source for the first IPV treatment includes hydrogen, the etching temperature is higher than the evaporation temperature of the liquid metal layer, the etching temperature is higher than the decomposition temperature of the carbon substrate, and the decomposition temperature of the carbon substrate is higher than the evaporation temperature of the liquid metal layer; performing a second IPV treatment on the side of the carbon substrate with the etched surface to obtain carbon microspheres; the second gas source for the second IPV treatment includes hydrogen and methane. The carbon microspheres prepared by this application thus include sp... 2 Hybridized carbon and sp 3 Hybridized carbon.

Description

Technical Field

[0001] This application relates to the field of micro / nano powder materials, specifically to carbon microspheres, their preparation methods, and applications. Background Technology

[0002] Due to its unique electronic structure, the carbon atom has multiple hybrid states, mainly including sp... 3 Hybridized carbon (such as diamond), sp 2 Hybridized carbon (such as graphene, fullerene, carbon nanotubes, etc.) and those containing sp and sp 2 Hybridized orbital materials (such as graphyne) and other hybridized states. These carbon materials with different hybridized states exhibit diverse chemical and physical properties, making carbon materials have broad application potential in many fields. However, carbon materials with a single hybridized state are difficult to meet the ever-increasing demand for comprehensive performance.

[0003] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0004] In a first aspect of this application, a method for preparing carbon microspheres is provided, comprising: forming a liquid metal layer on one side of a carbon substrate; performing a first microwave plasma chemical vapor deposition (MSV) treatment on the side of the carbon substrate having the liquid metal layer, raising the temperature of the carbon substrate to an etching temperature to obtain a carbon substrate with an etched surface; wherein a first gas source for the first MPV treatment includes hydrogen, the etching temperature is greater than the evaporation temperature of the liquid metal layer, the etching temperature is greater than the decomposition temperature of the carbon substrate, and the decomposition temperature of the carbon substrate is greater than the evaporation temperature of the liquid metal layer; performing a second MPV treatment on the side of the carbon substrate having the etched surface to obtain carbon microspheres; wherein a second gas source for the second MPV treatment includes hydrogen and methane.

[0005] Therefore, the liquid metal layer can prevent premature etching and nucleation of the carbon substrate, thereby reducing the risk of agglomeration on the carbon substrate surface and making the carbon substrate surface more prone to forming single spherical structures. The carbon substrate surface etched by hydrogen produces dangling bonds, with methane acting as a sp... 3 The source of hybrid carbon is that ionized methane gas can combine with dangling bonds on the carbon substrate surface, promoting spp formation on the carbon substrate surface. 2 Hybridized carbon to sp 3 The hybridization of carbon forms sp 3 The C / C bonds can then undergo secondary nucleation on the carbon substrate surface, forming diamond. Therefore, the carbon microspheres prepared in this application include sp... 2 Hybridized carbon and sp 3Hybridized carbon.

[0006] In some embodiments, the flow rate ratio of methane to hydrogen in the second gas source is (0-15):100. Thus, methane acts as a sp... 3 The source of hybrid carbon can be controlled by adjusting the amount of methane used; the sp2 content in carbon microspheres can be adjusted accordingly. 3 The content of hybrid carbon and crystal structure.

[0007] In some embodiments, the liquid metal layer comprises at least one selected from gallium, gallium-iron alloy, gallium-magnesium alloy, gallium-nickel alloy, gallium-iron-nickel alloy, gallium-zinc alloy, gallium-magnesium-zinc alloy, gallium-indium alloy, gallium-tin alloy, and gallium-indium-tin alloy. Therefore, gallium and gallium-based alloys are suitable for the method of preparing carbon microspheres according to this application.

[0008] In some embodiments, the carbon substrate includes at least one of graphite and glassy carbon. Therefore, selecting a suitable carbon substrate as the reaction substrate not only provides a stable platform for the growth of carbon microspheres, but also... 2 Sources of hybrid carbon.

[0009] In some embodiments, the formation of the liquid metal layer on one side of the carbon substrate satisfies at least one of the following conditions: the surface temperature of the carbon substrate is 21°C-25°C; and the relative humidity of the carbon substrate surface is less than or equal to 65%. Therefore, it is necessary to strictly control the surface temperature and relative humidity of the carbon substrate to ensure the formation of the liquid metal layer on the carbon substrate surface.

[0010] In some embodiments, the etching temperature is 800°C-850°C. Therefore, selecting a suitable etching temperature allows for effective etching of the carbon substrate while reducing the risk of over-etching.

[0011] In some embodiments, the second microwave plasma chemical vapor deposition (IPV) process satisfies at least one of the following conditions: the microwave power of the second IPV process is 3600W-4600W; the reaction time of the second IPV process is 30min-90min; the working pressure of the second IPV process is 17.3KPa-20KPa; and the temperature of the side of the carbon substrate with the etched surface during the second IPV process is 900℃-1100℃. Therefore, by controlling the parameters of the second IPV process, the sp content in the carbon microspheres can be adjusted. 2 Hybridized carbon and sp 3 The proportion of hybrid carbons, and sp 3 The morphology of hybrid carbon.

[0012] In a second aspect, this application provides carbon microspheres prepared by the aforementioned method, wherein the carbon microspheres comprise sp... 2 Hybridized carbon and sp 3 Hybridized carbon. As a result, the carbon microspheres of this application possess electrical conductivity, flexibility, good thermal conductivity, and hardness.

[0013] In some embodiments, the carbon microspheres have a particle size of 5 μm-300 μm. Therefore, the carbon microspheres of this application have a wide particle size range, and the particle size can be adjusted according to actual needs.

[0014] In some implementations, the sp 3 Hybridized carbon includes at least one of amorphous diamond and polycrystalline diamond. Therefore, this application can adjust the sp_t ratio according to actual needs. 3 Types of hybrid carbon.

[0015] In some implementations, the sp 2 Hybridized carbon includes graphite.

[0016] In a third aspect, this application provides the application of carbon microspheres obtained by the preparation method of the first aspect of this application and carbon microspheres of the second aspect of this application in battery electrode materials, cutting-edge semiconductor devices or human-friendly medical imaging materials. Attached Figure Description

[0017] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0018] Figure 1 This is a schematic diagram of a method for preparing carbon microspheres according to one embodiment of this application.

[0019] Figure 2 The coating effect of liquid gallium under different temperature conditions is shown, among which, Figure 2 Figure a shows the coating effect under the conditions of 24.3℃ and 57% relative humidity; Figure 2 Figure b shows the coating effect at 27℃. Figure 2 Figure c shows the coating effect at 19℃.

[0020] Figure 3 This is a characterization result diagram of the carbon microspheres in Example 1, where, Figure 3 Figure a in the image is a scanning electron microscope image of a single carbon microsphere; Figure 3 Figure b in the image shows the Raman spectrum of the carbon microspheres. Figure 3 Figure c in the figure shows the nano-force stage test curve of a single carbon microsphere.

[0021] Figure 4The figure shows the characterization results of the carbon microspheres in Example 2. Figure 4 Figure a in the image is a scanning electron microscope image of a single carbon microsphere; Figure 4 Figure b in the image shows the Raman spectrum of the carbon microspheres.

[0022] Figure 5 The figure shows the characterization results of the carbon microspheres in Example 3. Figure 5 Figure a in the image is a scanning electron microscope image of a single carbon microsphere; Figure 5 Figure b in the image shows the Raman spectrum of the carbon microspheres.

[0023] Figure 6 The figure shows the characterization results of the carbon microspheres in Example 4. Figure 6 Figure a in the image is a scanning electron microscope image of a single carbon microsphere; Figure 6 Figure b in the image shows the Raman spectrum of the carbon microspheres.

[0024] Figure 7 The figure shows the characterization results of the carbon microspheres in Comparative Example 1. Figure 7 Figure a in the image is a scanning electron microscope image of carbon microsphere clusters; Figure 7 Figure b in the image shows the Raman spectrum of the carbon microspheres. Detailed Implementation

[0025] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the carbon microspheres of this application, their preparation methods, and their applications. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0026] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is also expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0027] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0028] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0029] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0030] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. "First feature" and "second feature" may include one or more of the indicated feature.

[0031] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0032] Single-hybrid carbon materials have significant limitations in practical applications. For example, in the field of silicon-carbon anode materials for lithium-ion batteries, sp... 2 While hybrid carbon materials possess good electrical conductivity, they lack sufficient structural support, making it difficult for them to withstand the volume expansion of silicon particles, which could lead to the cracking of the anode material. 3 While hybrid diamond possesses high hardness, it exhibits poor electrical conductivity and is too rigid, lacking sufficient toughness, making it prone to chipping during use. Therefore, developing carbon materials with multiple hybrid states to overcome the limitations of single-hybrid carbon materials is of paramount importance.

[0033] In a first aspect, this application provides a method for preparing carbon microspheres, referring to... Figure 1 The method includes:

[0034] S100, a liquid metal layer is formed on one side of the carbon substrate.

[0035] Liquid metal generally refers to metals or alloys that are liquid at room temperature. The liquid metal used in this application has a low melting point, so it has good fluidity at room temperature and can flow on the surface of a carbon substrate to form a liquid metal layer.

[0036] In some embodiments, the liquid metal layer includes at least one selected from gallium, gallium-iron alloy, gallium-magnesium alloy, gallium-nickel alloy, gallium-iron-nickel alloy, gallium-zinc alloy, gallium-magnesium-zinc alloy, gallium-indium alloy, gallium-tin alloy, and gallium-indium-tin alloy. Therefore, gallium and gallium-based alloys are suitable for the method of preparing carbon microspheres according to this application.

[0037] In some embodiments, the carbon substrate includes at least one of graphite and glassy carbon. Therefore, selecting a suitable carbon substrate as the reaction substrate not only provides a stable platform for the growth of carbon microspheres, but also... 2 Sources of hybrid carbon.

[0038] In some embodiments, the carbon substrate contains 99.99% or more carbon.

[0039] As an example, the carbon content of the carbon substrate includes, but is not limited to, 99.99%, 99.999%, 99.9999%, or 100%.

[0040] In some embodiments, the surface of the carbon substrate is mechanically polished. This improves the flatness and smoothness of the carbon substrate surface, and a smooth carbon substrate can enhance the fluidity of the liquid metal, facilitating the formation of a uniform liquid metal layer.

[0041] In some embodiments, a liquid metal layer is formed on one side of the carbon substrate to satisfy at least one of the following conditions: the surface temperature of the carbon substrate is 21°C-25°C; the surface relative humidity of the carbon substrate is less than or equal to 65%.

[0042] During the formation of the liquid metal layer, strict control of the surface temperature and relative humidity of the carbon substrate is necessary. This is because at higher temperatures, the liquid metal exhibits higher fluidity and surface energy, resulting in a larger wetting angle between the liquid metal and the carbon substrate surface, making it difficult for the liquid metal to distribute evenly on the carbon substrate surface. At lower temperatures, the liquid metal solidifies too quickly, leading to the formation of uneven agglomerates on the carbon substrate surface. Controlling the relative humidity of the carbon substrate surface helps reduce hydration between the liquid metal layer and water molecules, thereby improving the stability of the liquid metal layer.

[0043] Taking gallium as the liquid metal and graphite as the carbon substrate as an example, under conditions of 24.3℃ and 57% relative humidity, the graphite surface was coated with liquid gallium, and the coating effect was as follows: Figure 2 As shown in Figure c, a liquid metal layer forms on the graphite surface; when the temperature rises to 27°C, the coating effect is as follows. Figure 2 As shown in Figure a, liquid gallium agglomerates into water droplets on the graphite surface, making it difficult to coat the graphite surface with gallium; when the temperature is reduced to 19℃, the coating effect is as follows. Figure 2 As shown in Figure b, liquid gallium condenses upon contact with the graphite surface, causing agglomeration on the graphite surface and affecting the coating effect.

[0044] As an example, the surface temperature of the carbon substrate can be 21°C, 21.5°C, 22°C, 22.5°C, 23°C, 23.5°C, 24°C, 24.5°C, or 25°C.

[0045] As an example, the surface relative humidity of the carbon substrate includes, but is not limited to, 0%, 15%, 30%, 45%, 60%, or 65%.

[0046] In some embodiments, a liquid metal layer is formed on one side of the carbon substrate while simultaneously satisfying the following conditions: the surface temperature of the carbon substrate is 21°C-25°C; and the surface relative humidity of the carbon substrate is less than or equal to 65%.

[0047] S200, A first microwave plasma chemical vapor deposition process is performed on the side of the carbon substrate with the liquid metal layer to raise the temperature of the carbon substrate to the etching temperature, so as to obtain a carbon substrate with an etched surface; the first gas source of the first microwave plasma chemical vapor deposition process includes hydrogen gas, the etching temperature is greater than the evaporation temperature of the liquid metal layer, the etching temperature is greater than the decomposition temperature of the carbon substrate, and the decomposition temperature of the carbon substrate is greater than the evaporation temperature of the liquid metal layer.

[0048] The working principle of microwave plasma chemical vapor deposition (MPCVD) is as follows: microwaves are generated by a microwave source, coupled through a waveguide and mode converter, and then enter the reaction chamber. Under the influence of the microwave electromagnetic field, hydrogen gas is excited into a plasma state. Plasma is an ionized gaseous substance composed of positive and negative ions generated after atoms and atomic groups have lost some electrons. The plasma forms in a spherical or ellipsoidal shape on a carbon substrate, and the high temperature of the plasma can heat the carbon substrate to the etching temperature. In this application, during the process of heating the carbon substrate to the etching temperature, the temperature first reaches the evaporation temperature of the liquid metal layer, at which point the liquid metal layer is rapidly removed through evaporation; then the temperature reaches the decomposition temperature of the carbon substrate, at which point the carbon substrate is etched by hydrogen gas.

[0049] Therefore, during plasma ignition and carbon substrate heating, the liquid metal layer isolates the hydrogen gas from the carbon substrate to protect it. Once the carbon substrate reaches the evaporation temperature of the liquid metal layer, it is rapidly removed, allowing hydrogen to begin etching. Simultaneously, the high-temperature covalent bond structure of the liquid metal facilitates the catalytic conversion of CH bonds to C / C bonds, resulting in the formation of uniform spherical carbon nuclei on the carbon substrate surface. Thus, the liquid metal layer prevents premature etching and nucleation of the carbon substrate, reducing the risk of agglomeration on the carbon substrate surface and making it more prone to forming a single spherical structure.

[0050] In some implementations, the etching temperature is 800°C-850°C. Therefore, selecting an appropriate etching temperature can effectively etch the carbon substrate while reducing the risk of over-etching.

[0051] As an example, the etching temperature can be 800℃, 805℃, 810℃, 815℃, 820℃, 825℃, 830℃, 835℃, 840℃, 845℃ or 850℃.

[0052] In some implementations, the purity of the hydrogen is greater than or equal to 99.99%.

[0053] As an example, the purity of hydrogen includes, but is not limited to, 99.99%, 99.999%, 99.9999%, or 100%.

[0054] S300, a second microwave plasma chemical vapor deposition process is performed on the etched side of the carbon substrate to obtain carbon microspheres; the second gas source for the second microwave plasma chemical vapor deposition process includes hydrogen and methane.

[0055] The carbon substrate surface etched with hydrogen produces dangling bonds, with methane acting as sp. 3 The source of hybrid carbon is that ionized methane gas can combine with dangling bonds on the carbon substrate surface, promoting sp2 bonding on the carbon substrate surface. 2 Hybridized carbon to sp 3The hybridization of carbon forms sp 3 The C-C bonds can then be nucleated twice on the carbon substrate surface to form diamond.

[0056] sp 2 Hybridized carbon to sp 3 The transformation of hybrid carbon into sp 3 The C / C bond formation process requires energy, allowing carbon atoms to overcome energy barriers and form sp bonds. 3 The diamond structure is a hybrid state. Therefore, the sp(s) content in carbon microspheres can be adjusted by controlling the energy level according to actual needs. 2 Hybridized carbon and sp 3 The proportion of hybrid carbon

[0057] Diamond formed on a carbon substrate initially exists in an amorphous state. As energy increases, the amorphous carbon can be transformed into ordered carbon atoms. These ordered carbon atoms act as seed crystals, which gradually grow and tend to grow first. <111> Diamond sheets are formed from surface-mounted diamonds. As the diamond sheets grow, they form a continuous, layered polycrystalline diamond structure through mutual compression and bonding between the grains.

[0058] In some embodiments, the flow rate ratio of methane to hydrogen in the second gas source is (0-15):100. Thus, methane acts as a sp... 3 The source of hybrid carbon can be controlled by adjusting the amount of methane used; the sp2 content in carbon microspheres can be adjusted accordingly. 3 The content of hybrid carbon and crystal structure.

[0059] As an example, the flow rate ratio of methane to hydrogen can be 0:100, 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, 11:100, 12:100, 13:100, 14:100, or 15:100.

[0060] Under the etching action of hydrogen gas, dangling bonds and free hydrocarbons or carbon ions are generated on the carbon substrate. When the flow rate ratio of methane to hydrogen is 0:100, that is, when no methane is introduced, the dangling bonds and free hydrocarbons or carbon ions recombine, and the carbon atoms rearrange to form sp. 3 hybridized carbon; but forming sp 3 In the process of hybridized carbon, its growth pattern changes from normal layered and hillock growth to irregular growth. This irregular growth leads to the aggregation of carbon atoms to form polycrystalline diamond, characterized by an inhomogeneous crystal structure and an irregular shape with sharp edges; and in addition to forming sp... 3 In addition to hybridized carbon, polycrystalline diamond also contains some sp atoms at its defects. 2Carbon in a hybrid state, therefore, carbon microspheres possess sp... 2 Hybridized carbon and sp 3 Hybridized carbon.

[0061] In some implementations, the purity of hydrogen and / or methane is greater than or equal to 99.99%.

[0062] As an example, the purity of hydrogen and / or methane includes, but is not limited to, 99.999%, 99.9999%, or 100%.

[0063] In some embodiments, the second microwave plasma chemical vapor deposition (PCVDC) process satisfies at least one of the following conditions: the microwave power of the second PCVDC process is 3600W-4600W; the reaction time of the second PCVDC process is 30min-90min; the working pressure of the second PCVDC process is 17.3KPa-20KPa; and the temperature of the side of the carbon substrate with the etched surface during the second PCVDC process is 900℃-1100℃. Therefore, by controlling the parameters of the second PCVDC process, the sp content in the carbon microspheres can be adjusted. 2 Hybridized carbon and sp 3 The proportion of hybrid carbons, and sp 3 The morphology of hybrid carbon.

[0064] As an example, the microwave power of the second microwave plasma chemical vapor deposition process can be 3600W, 3700W, 3800W, 3900W, 4000W, 4100W, 4200W, 4300W, 4400W, 4500W or 4600W.

[0065] As an example, the reaction time for the second microwave plasma chemical vapor deposition process can be 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, or 90 min.

[0066] As an example, the operating pressure of the second microwave plasma chemical vapor deposition process can be 17.3 kPa, 17.6 kPa, 17.9 kPa, 18.2 kPa, 18.5 kPa, 18.8 kPa, 19.1 kPa, 19.4 kPa, 19.7 kPa or 20 kPa.

[0067] As an example, the temperature on the side of the carbon substrate with the etched surface can be 900°C, 920°C, 940°C, 960°C, 980°C, 1000°C, 1020°C, 1040°C, 1060°C, 1080°C, or 1100°C.

[0068] In some embodiments, the second microwave plasma chemical vapor deposition process simultaneously meets the following conditions: the microwave power of the second microwave plasma chemical vapor deposition process is 3600W-4600W; the reaction time of the second microwave plasma chemical vapor deposition process is 30min-90min; the working pressure of the second microwave plasma chemical vapor deposition process is 17.3KPa-20KPa; and the temperature of the side of the carbon substrate with the etched surface in the second microwave plasma chemical vapor deposition process is 900℃-1100℃.

[0069] In a second aspect, this application provides carbon microspheres prepared by the aforementioned method, wherein the carbon microspheres comprise sp... 2 Hybridized carbon and sp 3 Hybridized carbon. As a result, the carbon microspheres of this application possess electrical conductivity, flexibility, good thermal conductivity, and hardness.

[0070] In some embodiments, the particle size of the carbon microspheres is 5 μm-300 μm. Therefore, the carbon microspheres of this application have a wide particle size range, and the particle size can be adjusted according to actual needs.

[0071] As an example, the particle size of carbon microspheres can be 5 μm, 10 μm, 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, 220 μm, 240 μm, 260 μm, 280 μm or 300 μm.

[0072] In some implementations, sp 3 Hybridized carbon includes at least one of amorphous diamond and polycrystalline diamond. Therefore, this application can adjust the sp_t ratio according to actual needs. 3 Types of hybrid carbon.

[0073] In some implementations, sp 2 Hybridized carbon includes graphite.

[0074] In a third aspect, this application provides the application of carbon microspheres obtained by the preparation method of the first aspect of this application and carbon microspheres of the second aspect of this application in battery electrode materials, cutting-edge semiconductor devices or human-friendly medical imaging materials.

[0075] The following specific embodiments illustrate the solution of this application. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0076] Example 1

[0077] The preparation of carbon microspheres includes the following steps:

[0078] S100. Take a graphite sheet with a carbon content of 99.999% and mechanically polish its surface. Then, place the polished graphite sheet in an environment with a temperature of 24.3℃ and a relative humidity of 57% for a period of time until the temperature and relative humidity of the graphite sheet are consistent with those of the environment. Then, coat the surface of the graphite sheet with liquid gallium metal. The liquid gallium metal flows on the surface of the graphite sheet to form a uniform liquid metal layer on the surface of the graphite sheet.

[0079] S200: A graphite sheet with a liquid metal layer is placed in the MPCVD reaction chamber. Hydrogen gas with a purity of 99.999% is introduced into the reaction chamber. The plasma glows in the hydrogen atmosphere. The heating operation is carried out while maintaining the ratio of working pressure to microwave power at 0.6 kPa / 100 W. When the temperature rises to 750°C, the liquid gallium metal is completely evaporated and removed. When the temperature continues to rise to 800°C, the surface of the graphite sheet is etched by hydrogen gas, generating free hydrocarbons or carbon ions, which causes the plasma to change from pink to white.

[0080] In step S300, 99.999% pure methane is introduced into the reaction chamber, and the flow rate ratio of methane to hydrogen is controlled at 1:10. Simultaneously, the microwave power of the reaction chamber is increased to 3600W, the working pressure is increased to 18KPa, and the surface temperature of the graphite sheet is increased to 912℃. After deposition for 1 hour, carbon microspheres are obtained. After stopping the methane supply, during the plasma shutdown process, hydrogen etches the connection points between the carbon microspheres and the graphite sheet, allowing the carbon microspheres to be separated from the graphite sheet surface by simple vibration treatment.

[0081] Example 2

[0082] The difference between Example 2 and Example 1 is as follows:

[0083] S300 increases the microwave power of the reaction chamber to 3800W, the working pressure to 18.3KPa, and the surface temperature of the graphite sheet to 1005℃.

[0084] Example 3

[0085] The difference between Example 3 and Example 1 is as follows:

[0086] S300 increases the microwave power of the reaction chamber to 4200W, the working pressure to 19KPa, and the surface temperature of the graphite sheet to 1100℃.

[0087] Example 4

[0088] The difference between Example 4 and Example 1 is that methane is not introduced into the reaction chamber.

[0089] Comparative Example 1

[0090] The difference between Comparative Example 1 and Example 1 is that the graphite sheet surface is not coated with liquid gallium.

[0091] Structural characterization

[0092] 1. The carbon microspheres obtained in Examples 1-4 and Comparative Example 1 were subjected to electron microscopy scanning. The instrument used was a Hitachi Regulus 8230.

[0093] 2. The carbon microspheres separated in Examples 1-4 and Comparative Example 1 were uniformly dispersed in ethanol. Then, the ethanol solution containing carbon microspheres was drop-cast onto the surface of a stainless steel substrate for Raman spectroscopy testing. The instrument was a HORIBA / LabRAM Odyssey with an excitation wavelength of 532 nm.

[0094] The characterization results of the carbon microspheres in Example 1 are as follows: Figure 3 As shown, Figure 3 Figure a in the image is a scanning electron microscope image of a single carbon microsphere. Figure 3 Figure b in the image shows the Raman spectrum of the carbon microspheres. (From...) Figure 3 As shown in Figure a, the carbon microspheres exhibit high sphericity and a smooth surface, with a particle size of 5.1 μm. (From...) Figure 3 As shown in Figure b, 1348.2cm -1 A distinct D peak is present at 1581.3 cm⁻¹, indicating numerous lattice defects in the carbon microspheres; -1 A distinct graphite phase G peak is present at 2695.1 cm⁻¹. -1 The presence of a distinct G' peak indicates that the carbon microspheres possess a graphene-like layered structure at the nanoscale, exhibiting good electrical conductivity. Furthermore, nanoscale force stage tests were performed on individual carbon microspheres from Example 1, and the resulting curves are shown in the figure. Figure 3 As shown in Figure c, the red line records the displacement (s) of the indenter, and the black line records the force (F) curve measured by the indenter. The red line indicates that the indenter was pressed down by 8 μm, which is larger than the particle size of the single sphere (5.1 μm). This suggests that the high hardness of the single sphere caused elastic deformation of the tungsten steel indenter. Furthermore, the force curve shows that under the ultimate pressure (90 mN) of the nanoscale force stage detector, the single sphere did not break or deform, while high-purity graphite particles of the same size would break when subjected to a force of less than 20 mN. This indicates that the carbon microspheres of Example 1 possess mechanical properties far exceeding those of high-purity graphite particles. This is because the carbon microspheres of Example 1 contain amorphous diamond.

[0095] The characterization results of the carbon microspheres in Example 2 are as follows: Figure 4 As shown, Figure 4 Figure a in the image is a scanning electron microscope image of a single carbon microsphere. Figure 4 Figure b in the image shows the Raman spectrum of the carbon microspheres. (From...) Figure 4 As shown in Figure a, the carbon microspheres exhibit high sphericity, with white diamond-like structures appearing on their surfaces. The particle size of each microsphere is 9.7 μm. Figure 4 As shown in Figure b, 1330.8cm -1 The presence of a diamond signal peak indicates that sp2 formation has occurred on the surface of the carbon microspheres. 3 Hybridized diamond; 1568cm -1 The presence of a graphite phase G peak at the location of the peak, along with its shift and overall broadening, indicates the presence of a large amount of sp in the carbon microspheres. 2 Mixed fossil graphite phase; 2700cm -1 The disappearance of the G' peak indicates that the carbon microspheres have lost their graphene-like multilayer structure, which theoretically would reduce their conductivity.

[0096] The characterization results of the carbon microspheres in Example 3 are as follows: Figure 5 As shown, Figure 5 Figure a in the image is a scanning electron microscope image of a single carbon microsphere. Figure 5 Figure b in the image shows the Raman spectrum of the carbon microspheres. (From...) Figure 5 As shown in Figure a, the carbon microspheres exhibit high sphericity, with a continuous hierarchical diamond crystal structure on their surface. The particle size of each microsphere is 45.2 μm. Figure 5 As shown in Figure b, 1332.1cm -1 There is a standard sp at that location 3 Hybrid diamond signal peak; 1580 cm⁻¹ -1 The graphite phase G peak weakens and evolves to 1450 cm⁻¹ -1 -1650cm -1 The hump indicates the sp of the carbon microspheres. 2 The graphite phase content of the mixed fossil further decreased; at the same time, 2700cm -1 The disappearance of the G' peak indicates that the carbon microspheres have lost their graphene-like multilayer structure, which theoretically would reduce their conductivity.

[0097] The characterization results of the carbon microspheres in Example 4 are as follows: Figure 6 As shown, Figure 6 Figure a in the image is a scanning electron microscope image of a single carbon microsphere. Figure 6 Figure b in the image shows the Raman spectrum of the carbon microspheres. (From...) Figure 6 As shown in Figure a, the carbon microspheres exhibit poor sphericity and an irregular shape characteristic of polycrystalline diamond crystal structures with sharp edges. Figure 6 As shown in Figure b, 1332.1cm -1 There is a standard sp at that location 3Hybrid diamond signal peak, 1580 cm⁻¹ -1 The graphite phase G peak at the location indicates that a large amount of sp2p2 remains in the carbon microspheres. 2 Hybrid graphitic carbon.

[0098] The characterization results of the carbon microspheres in Comparative Example 1 are as follows: Figure 7 As shown, Figure 7 Figure a in the image is a scanning electron microscope image of carbon microsphere clusters. Figure 7 Figure b in the image shows the Raman spectrum of the carbon microspheres. (From...) Figure 7 As shown in Figure a, the carbon microspheres exhibit a distinct cluster structure, and the cluster particle size cannot be accurately measured. The size of the cluster particles is much larger than the size of a single carbon microsphere in Example 1. This indicates that without coating with liquid gallium, uneven nucleation occurs on the graphite sheet surface, making it difficult to generate uniformly dispersed single spheres. Figure 7 As shown in Figure b, 1332.1cm -1 There is a standard sp at that location 3 Hybrid diamond signal peak, 1580 cm⁻¹ -1 The graphite phase G peak at the location indicates that a large amount of sp2p2 remains in the carbon microspheres. 2 Heterogeneous graphitic carbon; 1348.6 cm -1 A distinct D peak is present at 1581.3 cm⁻¹, indicating the presence of numerous graphite phase defect sites in the carbon microspheres. -1 There is obvious sp at the location 2 Graphite phase G peak and 2695.1 cm⁻¹ -1 A strong G' peak exists at this location.

[0099] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing carbon microspheres, characterized in that, include: A liquid metal layer is formed on one side of the carbon substrate; A first microwave plasma chemical vapor deposition process is performed on the side of the carbon substrate having the liquid metal layer, raising the temperature of the carbon substrate to the etching temperature to obtain the carbon substrate with an etched surface; The first gas source for the first microwave plasma chemical vapor deposition process includes hydrogen gas, the etching temperature is greater than the evaporation temperature of the liquid metal layer, the etching temperature is greater than the decomposition temperature of the carbon substrate, and the decomposition temperature of the carbon substrate is greater than the evaporation temperature of the liquid metal layer. A second microwave plasma chemical vapor deposition process is performed on the side of the carbon substrate with the etched surface to obtain carbon microspheres; the second gas source for the second microwave plasma chemical vapor deposition process includes hydrogen and methane.

2. The method according to claim 1, characterized in that, In the second gas source, the flow rate ratio of methane to hydrogen is (0-15):

100.

3. The method according to claim 1, characterized in that, The liquid metal layer comprises at least one of gallium, gallium-iron alloy, gallium-magnesium alloy, gallium-nickel alloy, gallium-iron-nickel alloy, gallium-zinc alloy, gallium-magnesium-zinc alloy, gallium-indium alloy, gallium-tin alloy, and gallium-indium-tin alloy; and / or, The carbon substrate includes at least one of graphite and glassy carbon.

4. The method according to any one of claims 1-3, characterized in that, The formation of a liquid metal layer on one side of the carbon substrate satisfies at least one of the following conditions: The surface temperature of the carbon substrate is 21℃-25℃; The relative humidity of the carbon substrate surface is less than or equal to 65%.

5. The method according to any one of claims 1-3, characterized in that, The etching temperature is 800℃-850℃.

6. The method according to any one of claims 1-3, characterized in that, The second microwave plasma chemical vapor deposition process satisfies at least one of the following conditions: The microwave power of the second microwave plasma chemical vapor deposition process is 3600W-4600W; The reaction time for the second microwave plasma chemical vapor deposition treatment is 30 min to 90 min; The operating pressure for the second microwave plasma chemical vapor deposition process is 17.3 kPa-20 kPa; In the second microwave plasma chemical vapor deposition process, the temperature of the carbon substrate on the side with the etched surface is 900℃-1100℃.

7. A carbon microsphere, characterized in that, The carbon microspheres are prepared by the method according to any one of claims 1-6, wherein the carbon microspheres comprise sp 2 Hybridized carbon and sp 3 Hybridized carbon.

8. The carbon microspheres according to claim 7, characterized in that, The carbon microspheres have a particle size of 5μm-300μm.

9. The carbon microspheres according to claim 7, characterized in that, The sp 3 Hybridized carbon includes at least one of amorphous diamond and polycrystalline diamond; and / or, The sp 2 Hybridized carbon includes graphite.

10. The application of a carbon microsphere as described in any one of claims 7-9, or a carbon microsphere prepared by the method as described in any one of claims 1-6, in battery electrode materials, advanced semiconductor devices, or human-friendly medical imaging materials.

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