Device and method for graphene in-situ growth coated copper nanoparticles

Abstract

The application discloses a device and method for in-situ growth of graphene coated copper nanoparticles. The device comprises a reaction container, a vapor growth component, which is arranged in the interior of the reaction container and serves as a space for the generation of copper nanoparticles and the reaction of graphene and copper nanoparticles, and a collection component, which is arranged in the interior of the reaction container and located at the upper end of the vapor growth component. By obtaining copper vapor under suitable temperature and pressure conditions and uniformly and evenly introducing gaseous carbon source, the method realizes catalysis, cracking, nucleation, growth and other processes, and finally obtains high-quality graphene coated copper nanoparticle composite material at the collection end. The method is simple in process and remarkable in effect, and can realize preparation of graphene uniformly coated copper nanoparticle composite material on a certain scale.

Description

Technical Field

[0001] This invention relates to the technical field of graphene and graphene composite material preparation and production equipment development, and particularly to an apparatus and method for in-situ growth of graphene coated with copper nanoparticles. Background Technology

[0002] Graphene possesses extremely high electrical and thermal conductivity, as well as excellent mechanical strength. Current research projects incorporate graphene as a reinforcing phase into other matrices to synergistically improve the electrical, mechanical, and optical properties of composite materials made from metals, non-metals, and polymers. Among these, graphene-reinforced copper-based composites are widely used in aerospace, defense, energy, and high-speed rail transportation due to their superior electrical and thermal conductivity and high mechanical strength.

[0003] Existing technologies using traditional physical mixing methods are prone to various problems such as graphene agglomeration, uneven mixing and dispersion, and poor interfacial bonding. Traditional chemical vapor deposition methods using copper foil as a substrate are prone to problems such as low graphene loading and obvious anisotropy. More advanced bubble chemical vapor deposition methods are prone to problems such as uneven size distribution of graphene-coated copper particles, large particle size range, and uneven coating. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing an apparatus and method for in-situ growth of graphene-coated copper nanoparticles.

[0005] To achieve the above objectives, the present invention employs the following technical solution: a device for in-situ growth of graphene-coated copper nanoparticles, comprising:

[0006] Reaction vessel;

[0007] An evaporation growth component, disposed inside the reaction vessel, comprising:

[0008] A copper vapor generation chamber is used to react and generate copper vapor;

[0009] The air inlet pipe is located at the central axis of the copper vapor generation chamber, so that the incoming graphene growth gas can diffuse evenly to the surroundings and fully react with the copper vapor.

[0010] A collection component is disposed inside the reaction vessel and located at the upper end of the evaporation growth component. The collection component is used to collect the graphene-coated copper nanoparticles generated in the reaction.

[0011] As a further description of the above technical solution, the upper and lower ends of the reaction vessel are respectively fixed with a first flange and a second flange for sealing the reaction vessel.

[0012] As a further description of the above technical solution, the copper vapor generation chamber includes a crucible, which is used to load copper material and melt the copper material to generate copper vapor;

[0013] The evaporation growth component also includes a gas-dispersing umbrella, which is disposed inside the crucible and is used to uniformly disperse the carbon source gas, reducing gas, and inert gas into the interior of the crucible.

[0014] It also includes a throat tube, which has the same width at both ends and narrows in the middle. One end of the throat tube is located at the opening of the crucible, and the other end of the throat tube is located below the collecting component and there is a distance between the throat tube and the lower end face of the collecting component.

[0015] As a further description of the above technical solution, the first flange is provided with a first vent for discharging the waste gas inside the reaction vessel to the outside.

[0016] The second flange has at least one first inlet for introducing carbon source gas, reducing gas, inert gas and dopant source gas, at least one second inlet and a third inlet for introducing inert gas and reducing gas.

[0017] As a further description of the above technical solution, a hollow base is provided below the crucible, and multiple through holes are distributed on the inner wall of the crucible, the through holes being connected to the second air inlet.

[0018] The air intake pipe is a connecting rod installed inside the base. The connecting rod is a hollow tube. One end of the connecting rod passes through the crucible and is connected to the gas equalization umbrella. The other end of the connecting rod is connected to the first air intake.

[0019] As a further description of the above technical solution, the collecting component is a water-cooled collecting tray, the inside of which is a hollow structure, and a cooling water pipe is provided on one side of the water-cooled collecting tray. The cooling water pipe passes through the first flange and is connected to an external cold water source.

[0020] As a further description of the above technical solution, the first flange and the reaction vessel are quick-release connected, which allows the collection component to be quickly removed.

[0021] A method for in-situ growth of graphene-coated copper nanoparticles, comprising the following steps:

[0022] S1, add copper material into the crucible of the cavity and evacuate it. After reaching the target vacuum level, introduce inert gas to normal pressure.

[0023] S2, set the program to heat to the target temperature and hold it, so that the copper material is completely melted and copper vapor is generated. When heating and holding the crucible, the cavity is kept at normal pressure and protected by inert gas and reducing gas.

[0024] S3, turn on the vacuum pump and introduce gaseous carbon source, reducing gas and other gases into the chamber to produce graphene-coated copper nanoparticles.

[0025] S4. After the reaction is complete, purge the sample collection tray with an inert protective gas until the temperature and pressure are normal, and then remove the sample collection tray to obtain the desired graphene-coated copper nanoparticle sample.

[0026] As a further description of the above technical solution, in step S1, the target vacuum level is 10. 0 -10 -3 Pa, preferably, the target vacuum level is <10. -2 pa;

[0027] In step S2, the target temperature is 1050-1150℃, preferably 1125℃.

[0028] As a further description of the above technical solution, in step S1, the inert gas is any one or more combinations of argon, nitrogen, and helium, with nitrogen being the preferred inert gas;

[0029] In step S3, the remaining gas is an inert gas or an inert gas and a dopant source gas, wherein the dopant source gas is one or both of hydrogen sulfide and ammonia.

[0030] In step S2, the gaseous carbon source is any one or a combination of ethylene, methane, acetylene, propylene, ethanol vapor, and acetone vapor, preferably methane, ethylene, and acetylene.

[0031] The present invention has the following beneficial effects:

[0032] 1. This invention provides a method and apparatus for preparing graphene-coated copper nanoparticles by in-situ growth. The method involves obtaining copper vapor under suitable temperature and pressure conditions, while simultaneously introducing a gaseous carbon source in a uniformly dispersed manner. Through processes such as catalysis, pyrolysis, nucleation, and growth, high-quality graphene-coated copper nanoparticle composite materials are ultimately obtained at the collection end. This method is simple, effective, and can achieve large-scale preparation of graphene-coated copper nanoparticle composite materials.

[0033] 2. This invention uses chemical vapor deposition to catalyze the in-situ growth of graphene on copper vapor, thereby obtaining a uniformly coated graphene-copper nanoparticle composite material. This avoids the problems of graphene agglomeration, inability to mix evenly, and poor interfacial bonding that exist in traditional physical mixing methods, as well as the problems of copper powder hardening, low graphene loading, and low catalytic growth efficiency that exist in traditional chemical vapor deposition methods.

[0034] 3. This invention utilizes copper vapor as a substrate for graphene catalysis and growth. The copper vapor particles are uniform in size and morphology, and the graphene is uniformly coated on them, avoiding the problems of low size uniformity, large span, and low coating integrity of copper particles coated by-products in the copper liquid bubbling graphene growth process.

[0035] 4. The present invention provides an apparatus for preparing graphene-coated copper nanoparticles. Copper vapor is obtained by heating copper material under appropriate temperature and pressure conditions. At the same time, a gaseous carbon source is uniformly dispersed and catalytically decomposed at high temperature, so that high-quality graphene-coated copper nanoparticle composite material can be obtained on a condensation collection plate.

[0036] 5. The device provided by the present invention utilizes the combination of a gas-dispersing umbrella, a graphite crucible, and a throat tube. After the carbon source gas is dispersed by the gas-dispersing umbrella, the carbon source gas can react more fully with the copper vapor. Then, after passing through the narrowing part of the throat tube, the copper vapor can more easily combine with graphene to obtain graphene-coated copper nanoparticles. After the particles are ejected from the other end of the throat tube, they can fall directly onto the collection tray above. After removing the collection tray, the graphene-coated copper nanoparticle sample can be easily obtained. Attached Figure Description

[0037] Figure 1 A schematic diagram of a reaction apparatus for graphene-coated copper nanoparticles;

[0038] Figure 2 This is a cross-sectional view of the reaction apparatus;

[0039] Figure 3 This is a schematic diagram of the interaction between the air-regulating umbrella and the throat.

[0040] Figure 4 This is a schematic diagram showing the assembly of the gas-distributing umbrella and the crucible.

[0041] Figure 5 This is a scanning electron microscope image of graphene-coated copper nanoparticle powder material prepared using the method of this application in one embodiment;

[0042] Figure 6 This is a scanning electron microscope image of graphene-coated copper nanoparticle powder material prepared using the method of this application in one embodiment of the present invention;

[0043] Figure 7This is a scanning electron microscope image of graphene-coated copper nanoparticle powder material prepared using the method of this application in one embodiment;

[0044] Figure 8 EDX spectrum;

[0045] Figure 9 Raman characterization diagram;

[0046] Figure 10 The image shows a scanning electron microscope image of the graphene-coated copper nanoparticles prepared in Comparative Example 2.

[0047] Legend:

[0048] 1. Reaction vessel;

[0049] 2. Evaporation growth component; 21. Crucible; 211. Through hole; 22. Base; 23. Connecting rod; 24. Gas distribution umbrella; 25. Throat tube;

[0050] 3. Collection components; 31. Water-cooled collection tray; 32. Cooling water pipes;

[0051] 4. First flange; 41. First air outlet; 42. Quick-tightening locking wheel;

[0052] 5. Second flange; 51. First air inlet; 52. Second air inlet; 53. Third air inlet. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0054] This application provides an apparatus and method for in-situ growth of graphene-coated copper nanoparticles to address the problem that in the prior art, when graphene is produced using chemical vapor deposition, the resulting graphene-coated copper nanoparticles are mostly uneven in size, and in fact, most of the produced graphene-coated copper nanoparticles are impurities. The apparatus provided in this application heats copper material into copper vapor in a graphite crucible 21, and uses a gas-distributing umbrella 24 to uniformly introduce carbon source gas and corresponding protective gas into the graphite crucible 21. At a suitable temperature, the carbon source grows graphene in-situ on top of the copper vapor under its catalysis, so as to obtain graphene-coated copper nanoparticles with uniform size and complete and uniform coating on the collection plate. It should be noted that this application utilizes the combination of the gas-dispersing umbrella 24, the graphite crucible 21, and the throat tube 25. After the carbon source gas is dispersed by the gas-dispersing umbrella 24, the carbon source gas can react more fully with the copper vapor. Then, after passing through the narrowing part of the throat tube 25, the copper vapor and graphene can combine more easily to obtain graphene-coated copper nanoparticles. After the particles are ejected from the other end of the throat tube 25, they can fall directly onto the collection plate above. After removing the collection plate, the graphene-coated copper nanoparticle sample can be easily obtained.

[0055] Reference Figure 1-4 An embodiment of an apparatus for in-situ growth of graphene-coated copper nanoparticles provided by the present invention mainly includes the following structure:

[0056] The reaction vessel 1, or reaction chamber, is a hollow cylinder in this embodiment. However, in other feasible embodiments, the reaction chamber can also be other regular shapes, such as a square hollow cylinder. The reaction vessel 1 has a quartz cavity wall, which is transparent, inert, corrosion-resistant, and smooth, making it difficult to adsorb copper vapor. If the quartz material is replaced with graphite, it will be ablated under high temperature conditions. If corundum tubes are used, their opacity makes it difficult to observe the internal conditions of the cavity. If ceramic is used, its high roughness and porosity will make it easier for copper vapor to adhere. If high-temperature resistant metals are used, they are also opaque and easily alloy with copper, introducing heterogeneous metallic impurities.

[0057] The reaction vessel 1 is a sealed container during use, mainly sealed by the first flange 4 and the second flange 5 located at the upper and lower ends of the reaction vessel 1. In this embodiment, the first flange 4 is the upper flange and the second flange 5 is the lower flange. The first flange 4 and the second flange 5 not only serve to fix and seal the entire reaction vessel 1, but also have air inlets, air outlets and cooling water inlets designed on the end faces of the upper and lower flanges, providing places for the entry of reaction gases, the discharge of waste gases, the maintenance of vacuum, and the introduction of cooling water.

[0058] Combination Figure 2-4A key structure in this application is the evaporation growth component 2, which is located inside the reaction vessel 1. This component includes a copper vapor generation chamber for generating copper vapor, and an inlet pipe positioned along the central axis of the copper vapor generation chamber to ensure that the incoming graphene growth gas diffuses evenly and fully contacts and reacts with the copper vapor.

[0059] The copper vapor generating component is a crucible 21. In this embodiment, the crucible 21 is made of graphite, i.e., a graphite crucible 21. Its main function is to hold the copper material and melt it into copper vapor, using the copper vapor as one of the reaction raw materials. The crucible 21 is heated by resistance wire radiation, a relatively mature heating method that will not be elaborated upon in this embodiment. Multiple through holes 211 are distributed on the inner wall of the crucible 21. These through holes 211 are connected to the second air inlet 52, allowing the gas from the second air inlet 52 to be drawn out through the through holes 211, thus attracting the copper vapor inward and ensuring complete and sufficient contact with the carbon source gas for complete graphene coating.

[0060] The evaporation growth component also includes a gas-dispersing umbrella 24, please refer to [link / reference]. Figure 3 A gas-distributing umbrella 24 is positioned at the center of the graphite crucible 21. The gas-distributing umbrella 24 includes a connecting rod 23, which passes through the center of the graphite crucible 21 and connects to the first air inlet 51 on the lower flange. The connecting rod 23 is a hollow tube, which can disperse the carbon source gas, reducing gas, inert gas, and dopant source gas introduced into the first air inlet 51 into the graphite crucible 21. Multiple hollow tubes with small holes are distributed at the top of the connecting rod 23, so that the above gases can be evenly dispersed into the graphite crucible 21, so that they can react more fully with the copper vapor heated in the graphite crucible 21.

[0061] It also includes a throat 25, which has a structure that is the same width at both ends and narrows in the middle. One end of the throat 25 is located directly above the graphite crucible 21, and the wider end of the throat 25 has the same opening diameter as the graphite crucible 21. When the generated copper vapor meets the growth gas ejected from the gas distribution umbrella 24, it will first be gathered and collected by the wider lower edge of the throat 25, and then enter the narrower middle part where it will be compressed and accelerated, thereby increasing the collision between the activated carbon material and the copper vapor, accelerating the nucleation and growth of the activated carbon material on the copper vapor to coat graphene, and finally decelerating and depositing on the water-cooled collection plate 31. In summary, the throat 25 plays the role of "gathering and collecting - accelerating collision - decelerating deposition".

[0062] As for the water-cooled collection plate 31 mentioned above, the water-cooled collection plate 31 has a hollow structure. Cooling water pipes 32 are installed in some parts of the water-cooled collection plate 31. The cooling water pipes 32 pass through the first flange 4 and are connected to an external cold water source, so as to keep the water-cooled collection at a low temperature, so as to adsorb and condense the graphene-coated copper nanoparticles for collection.

[0063] For crucible 21, a hollow base 22 is provided at its bottom. The air inlet pipe, i.e., the connecting rod 23, passes through the hollow base 22 and connects to the first air inlet 51 of the second flange 5. For a detailed description of the first flange 4 and the second flange 5 mentioned above, as well as their related structures, please refer to [link to relevant documentation]. Figure 2 A first air outlet 41 is provided on the upper end face of the first flange 4 to discharge exhaust gas. The first air outlet 41 can be used in conjunction with an external vacuum pump to maintain the target vacuum level. The first flange 4 also has a cooling inlet and an outlet for cooling the flange. The first flange 4 includes a quick-release end face fixed by a quick-tightening locking wheel 42 for rapid removal and collection of the graphene-coated copper nanoparticles after condensation. The second flange 5 has at least one first air inlet 51, at least one second air inlet 52, at least one third air inlet, and a cooling water inlet / outlet. The first air inlet 51 provides the entry of carbon source gas, hydrogen reducing gas, inert protective gas, and dopant source gas. The second air inlet 52 and the third air inlet provide the entry of inert protective gas and hydrogen reducing gas. There is one first air inlet 51, through which the gas is introduced to support the growth of graphene. There are two second air inlets 52, which are symmetrically distributed about the center of the end face. The gas introduced through them flows out from the small holes in the side wall of the graphite crucible 21, which gathers the copper vapor inside the crucible 21 inward. There are two third air inlets, which are also symmetrically distributed about the center of the end face. The gas introduced through them mainly acts as an air curtain to block and isolate the overflowing copper vapor, reaction gas and leaked oxygen.

[0064] refer to Figure 5 - Figure 10 An embodiment of a method for in-situ growth of graphene-coated copper nanoparticles provided in this application includes the following steps:

[0065] S1. Add 1 kg of 99.99% pure copper material to the graphite crucible 21 in the cavity, then close the cavity lid and evacuate. When the vacuum level reaches 10⁻² Pa, turn off the vacuum pump. Introduce 1000 sccm of argon gas into any one, two, or three of the inlet ports 1, 2, and 3 until the cavity reaches atmospheric pressure.

[0066] S2. Set the program to heat to 1125℃ and hold for 30 minutes to completely melt the copper material. During this period, maintain normal pressure in the cavity and protect it with inert gas and reducing gas. Inlet 1 is filled with 500 sccm of argon and 50 sccm of hydrogen, inlet 2 is filled with 100 sccm of argon and 5 sccm of hydrogen, and inlet 3 is filled with 500 sccm of argon and 10 sccm of hydrogen.

[0067] S3. After the heat preservation is completed, start the growth process. Keep the temperature at 1125℃, turn on the vacuum pump, and then change the gas type and flow rate in inlet 1 to 100 sccm of methane, 50 sccm of hydrogen and 400 sccm of argon. Keep the gas intake of inlet 2 and inlet 3 consistent with that in step S2.

[0068] S4. After the reaction is complete, purge the sample collection tray with an inert protective gas until the temperature and pressure are normal, and then remove the sample collection tray to obtain the desired graphene-coated copper nanoparticle sample.

[0069] Scanning electron microscope images of the graphene-coated copper nanoparticle powder material prepared in this embodiment are shown below. Figure 5 As shown, the graphene-coated copper nanoparticles exhibit uniform size, complete structure, smooth surface, clear boundaries between particles, and no agglomeration or fusion. The particle size is approximately 80-110 nm. Under this equipment and process, graphene can grow and coat copper nanoparticles uniformly in situ, avoiding the problems of powder agglomeration, uneven mixing, poor interfacial bonding, and powder agglomeration that occur in traditional preparation methods.

[0070] To characterize the quality of graphene coated on the surface of copper particles, the copper in the graphene-coated copper nanoparticles was removed using a conventional etching process, followed by Raman characterization. The etching process involved placing an appropriate amount of graphene-coated copper nanoparticle powder in a container, adding a suitable amount of 3 mol / L ferric chloride solution, stirring for 30 minutes, filtering, washing with deionized water until neutral, and then drying at 80°C. The Raman characterization results are as follows: Figure 9As shown, four sharp and highly symmetrical characteristic peaks of graphene can be clearly seen: the D peak at 1350 cm⁻¹, the G peak at 1580 cm⁻¹, the 2D peak at 2700 cm⁻¹, and the 2D' peak at 3250 cm⁻¹, where ID / IG = 0.285. It should be noted that the appearance of the D peak is not due to the presence of sp³ hybridized amorphous carbon, but rather because the graphene loses its support after detaching from the copper particles. Furthermore, the graphene itself has low out-of-plane bending stiffness, and slight thermal and mechanical disturbances can lead to wrinkles. Therefore, the appearance of the D peak here is the result of the edge effect brought about by the wrinkled stacking characteristics of graphene. In addition, the 2D' characteristic peak, which is unique to high-quality powder, is also present. All of these indicate that the graphene coating on the surface of the copper particles is of high quality.

[0071] In another embodiment, a method for in-situ growth of graphene-coated copper nanoparticles includes the following steps:

[0072] S1. Add 1 kg of 99.99% pure copper material to the graphite crucible 21 in the cavity, then close the cavity lid and evacuate. When the vacuum level reaches 10⁻² Pa, turn off the vacuum pump. Introduce 1000 sccm of argon gas through any one, two, or three of the inlet ports 1, 2, and 3 until the cavity reaches atmospheric pressure.

[0073] S2. Set the program to heat to 1125℃ and hold for 30 minutes to completely melt the copper material. During this period, maintain normal pressure in the cavity and protect it with inert gas and reducing gas. Inlet 1 is filled with 500 sccm of argon and 50 sccm of hydrogen, inlet 2 is filled with 100 sccm of argon and 5 sccm of hydrogen, and inlet 3 is filled with 500 sccm of argon and 10 sccm of hydrogen.

[0074] S3. After the heat preservation is completed, start the growth process. Keep the temperature at 1125℃, turn on the vacuum pump, and then change the gas type and flow rate in inlet 1 to 150 sccm of methane, 50 sccm of hydrogen and 400 sccm of argon. Keep the gas intake of inlet 2 and inlet 3 consistent with that in step S2.

[0075] S4. After the reaction is complete, purge the sample collection tray with an inert protective gas until the temperature and pressure are normal, and then remove the sample collection tray to obtain the desired graphene-coated copper nanoparticle sample.

[0076] Scanning electron microscope images of the graphene-coated copper nanoparticle powder material prepared in this embodiment are shown below. Figure 6 As shown, it can be clearly seen that the graphene-coated copper nanoparticles are uniform in size, have a complete structure, a smooth surface, clear boundaries between particles, and no agglomeration or fusion.

[0077] In another embodiment, a method for in-situ growth of graphene-coated copper nanoparticles includes the following steps:

[0078] S1. Add 1 kg of 99.99% pure copper material to the graphite crucible 21 in the cavity, then close the cavity lid and evacuate. When the vacuum level reaches 10⁻² Pa, turn off the vacuum pump. Introduce 1000 sccm of argon gas into any one, two, or three of the inlet ports 1, 2, and 3 until the cavity reaches atmospheric pressure.

[0079] S2. Set the program to heat to 1125℃ and hold for 30 minutes to completely melt the copper material. During this period, maintain normal pressure in the cavity and protect it with inert gas and reducing gas. Inlet 1 is filled with 500 sccm of argon and 50 sccm of hydrogen, inlet 2 is filled with 100 sccm of argon and 5 sccm of hydrogen, and inlet 3 is filled with 500 sccm of argon and 10 sccm of hydrogen.

[0080] S3. After the heat preservation is completed, start the growth process. Keep the temperature at 1125℃, turn on the vacuum pump, and then change the gas type and flow rate in inlet 1 to 100 sccm of methane, 50 sccm of hydrogen and 400 sccm of argon. Introduce an additional 20 sccm of ammonia. Keep the gas intake of inlet 2 and inlet 3 consistent with that in step S2.

[0081] S4. After the reaction is complete, purge the sample collection tray with an inert protective gas until the temperature and pressure are normal, and then remove the sample collection tray to obtain the desired graphene-coated copper nanoparticle sample.

[0082] Scanning electron microscope images of the graphene-coated copper nanoparticle powder material prepared in this embodiment are shown below. Figure 7 As shown in the figure, the graphene-coated copper nanoparticles exhibit uniform size, intact structure, smooth surface, clear particle boundaries, and no agglomeration or fusion. Furthermore, we performed EDX energy dispersive spectroscopy analysis to determine the presence and content of nitrogen doping, as shown in the results. Figure 8 As shown, nitrogen was successfully incorporated into graphene, with a carbon-to-nitrogen ratio of 7:3. Furthermore, no iron residue from the etching agent was observed, indicating thorough cleaning. The small amount of copper found is attributed to the uniform and perfect coating of copper particles with graphene; although stirring was performed during etching, some copper particles were still not etched.

[0083] Comparative Example 1:

[0084] The graphene-coated copper nanoparticles in this comparative example are solid particles separated and collected during the preparation of graphene powder by chemical vapor deposition.

[0085] Specifically, the method for preparing graphene powder refers to the production using the equipment specified in Chinese Patent (CN113461000A), which includes the following steps: first, the chamber is evacuated to 10⁻² Pa, then an inert protective gas is introduced to atmospheric pressure, and then the electromagnetic induction heating device is turned on to heat the graphite crucible 21 to 1200-1500℃ to melt the copper block into a liquid state. Then, the ratio of methane, hydrogen and inert gas is precisely controlled by a gas flow control system, so that the mixture of the three gases enters the liquid copper in the graphite crucible 21 through an aeration device, thereby forming bubbles of adjustable size in the copper liquid. The generation of bubbles provides a "bubble cavity" for the growth of graphene. Graphene forms on the inner surface of the bubble cavity. As the bubbles rise in the copper liquid and burst on the surface of the copper liquid, graphene powder is generated and carried out of the reaction chamber by the airflow disturbance. The powder can then be collected at the rear end of the chamber. After collection, lightweight graphene powder and particles with higher bottom density are obtained by centrifugation.

[0086] like Figure 10 The image shown is an SEM image of the denser powder obtained from the lower layer separation. It can be clearly seen that it is not entirely composed of particulate matter. Due to the large specific surface area of ​​graphene and the surface effect of nanoparticles, agglomeration and adsorption occur between graphene powder sheets, between small particles, and between powders and particles. It is difficult to separate pure graphene-coated copper nanoparticles. In addition, it can be seen that the size distribution of copper particles is not uniform and the sizes are different, which is not conducive to maintaining the uniformity of performance in later practical applications.

[0087] Comparative Example 2:

[0088] Using copper powder as raw material, under low pressure conditions, 20 sccm of ethylene, 10 sccm of hydrogen and 100 sccm of nitrogen were introduced into a quartz tube furnace and kept at 850℃ for 30 minutes. After the end, 100 sccm of nitrogen was introduced to cool to room temperature and the material was taken out. It was found that the growth had failed. All the copper powder was clumped together and stuck to the crucible 21. It could not be separated or dispersed, and the copper powder lost its original granular morphology.

[0089] In summary, this invention provides a method and apparatus for preparing graphene-coated copper nanoparticles through in-situ growth. By obtaining copper vapor under suitable temperature and pressure conditions, and simultaneously introducing a gaseous carbon source in a uniformly dispersed manner, the process involves catalysis, pyrolysis, nucleation, and growth, ultimately yielding a high-quality graphene-coated copper nanoparticle composite material at the collection end. This method is simple, highly effective, and can achieve large-scale preparation of graphene-coated copper nanoparticle composite materials.

[0090] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A device for in-situ growth of graphene-coated copper nanoparticles, characterized in that, include: The reaction vessel has a first flange and a second flange fixed at its upper and lower ends for sealing the reaction vessel, and the second flange has at least one first inlet for introducing carbon source gas, reducing gas, inert gas and dopant source gas. An evaporation growth component, disposed inside the reaction vessel, comprising: A copper vapor generation chamber is used to react and generate copper vapor; The air inlet pipe is located at the central axis of the copper vapor generation chamber, so that the incoming graphene growth gas can diffuse evenly to the surroundings and fully react with the copper vapor. A collection component is disposed inside the reaction vessel and located at the upper end of the evaporation growth component. The collection component is used to collect the graphene-coated copper nanoparticles generated in the reaction. The copper vapor generation chamber includes a crucible for loading copper material and melting the copper material to generate copper vapor. A hollow base is provided below the crucible. The evaporation growth component also includes a gas-dispersing umbrella, which is disposed inside the crucible and is used to uniformly disperse the carbon source gas, reducing gas, and inert gas into the interior of the crucible. It also includes a throat tube, which has the same width at both ends and narrows in the middle. One end of the throat tube is located at the opening of the crucible, and the other end of the throat tube is located below the collecting component and there is a distance between the throat tube and the lower end face of the collecting component. The air intake pipe is a connecting rod installed inside the base. The connecting rod is a hollow tube. One end of the connecting rod passes through the crucible and is connected to the gas equalization umbrella. The other end of the connecting rod is connected to the first air intake.

2. The apparatus for in-situ growth of graphene-coated copper nanoparticles according to claim 1, characterized in that, The first flange has a first vent for discharging waste gas from the reaction vessel. The second flange has at least one second inlet and one third inlet for introducing inert gas and reducing gas.

3. The apparatus for in-situ growth of graphene-coated copper nanoparticles according to claim 2, characterized in that, The inner wall of the crucible has multiple through holes, which are connected to the second air inlet.

4. The apparatus for in-situ growth of graphene-coated copper nanoparticles according to claim 1, characterized in that, The collecting component is a water-cooled collecting tray with a hollow interior. A cooling water pipe is provided on one side of the water-cooled collecting tray, which passes through the first flange and is connected to an external cold water source.

5. The apparatus for in-situ growth of graphene-coated copper nanoparticles according to claim 1, characterized in that, The first flange is quick-released to the reaction vessel, allowing the collection component to be removed quickly.

6. A method for in-situ growth of copper-coated graphene nanoparticles using the apparatus for in-situ growth of graphene nanoparticles according to any one of claims 1-5, characterized in that, The specific steps include: S1, add copper material into the crucible of the cavity and evacuate it. After reaching the target vacuum level, introduce inert gas to normal pressure. S2, set the program to heat to the target temperature and hold it, so that the copper material is completely melted and copper vapor is generated. When heating and holding the crucible, the cavity is kept at normal pressure and protected by inert gas and reducing gas. S3, turn on the vacuum pump and introduce gaseous carbon source, reducing gas and other gases into the chamber to produce graphene-coated copper nanoparticles. S4. After the reaction is complete, purge the sample collection tray with an inert protective gas until the temperature and pressure are normal, and then remove the sample collection tray to obtain the desired graphene-coated copper nanoparticle sample.

7. The method for in-situ growth of graphene-coated copper nanoparticles according to claim 6, characterized in that, In step S1, the target vacuum level is 10. 0 -10 -3 pa; In step S2, the target temperature is 1050-1150℃.

8. The method for in-situ growth of graphene-coated copper nanoparticles according to claim 7, characterized in that, Target vacuum degree <10 -2 pa.

9. The method for in-situ growth of graphene-coated copper nanoparticles according to claim 7, characterized in that, The target temperature is 1125℃.

10. The method for in-situ growth of graphene-coated copper nanoparticles according to claim 6, characterized in that, In step S1, the inert gas is any one or a combination of argon, nitrogen, and helium; In step S3, the remaining gas is an inert gas or an inert gas and a dopant source gas, wherein the dopant source gas is one or both of hydrogen sulfide and ammonia. In step S3, the gaseous carbon source is any one or a combination of ethylene, methane, acetylene, propylene, ethanol vapor, and acetone vapor.

11. The method for in-situ growth of graphene-coated copper nanoparticles according to claim 10, characterized in that, The inert gas is nitrogen; the gaseous carbon source is methane, ethylene, or acetylene.

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