A method for in-situ preparation of graphene-copper nanocluster composite material by microwave plasma and product thereof

Abstract

The application belongs to the technical field of nanocomposite material preparation, and specifically discloses a method for in-situ preparation of graphene-copper nanocluster composite material by microwave plasma and a product thereof, which solves the problems of agglomeration, low purity and complicated process in the prior art preparation. In the method, a soluble copper salt solution is atomized into aerosol, mixed with a carrier gas and acetylene, and then introduced into a microwave plasma reaction cavity, so that the reduction of copper salt, the formation of CuNCs and the coating of graphene are completed in one step. The primary product is subjected to heat treatment in a tubular furnace to obtain the target composite material. The one-step synthesis of the application is superior in feeding, and the product is uniform in dispersion, controllable in structure, efficient in environmental protection, and high in industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of nanocomposite material preparation technology, specifically relating to a method for one-step in-situ preparation of graphene-coated copper nanocluster composite materials using microwave plasma and the resulting products. Background Technology

[0002] Graphene-copper nanocomposites have broad application prospects in electronic packaging, lithium-ion batteries, catalysis, and other fields due to their excellent electrical, thermal, and mechanical properties. In particular, graphene-coated copper nanoclusters with a core-shell structure can effectively utilize the high conductivity and chemical stability of graphene to inhibit the oxidation and aggregation of copper cores.

[0003] Currently, the mainstream methods for preparing such core-shell structured materials include liquid-phase chemical reduction, thermal decomposition, and chemical vapor deposition (CVD). However, existing technologies generally suffer from the following problems: 1) Cumbersome steps: They usually require multiple reaction steps, such as first synthesizing copper nanoparticles and then coating them with a carbon layer through additional steps, which is complex and time-consuming; 2) Severe product aggregation: Copper nanoparticles have high surface energy and are prone to aggregation without in-situ protection, resulting in uneven coating or the formation of bare copper without coating; 3) Low purity and crystallinity: Surfactants or reducing agents introduced by the liquid-phase method are difficult to remove completely, contaminating the product interface and affecting conductivity; 4) Poor controllability: It is difficult to simultaneously and precisely control the copper core size and graphene shell thickness at the atomic / nanoscale.

[0004] Therefore, developing an efficient, clean, one-step in-situ synthesis method with controllable structure has significant industrial value. Summary of the Invention This invention aims to solve the technical problems existing in the preparation of graphene-coated copper nanoclusters, such as cumbersome processes, easy product agglomeration, low purity, and poor structural controllability. It provides a method for one-step in-situ preparation of graphene-copper nanocluster composite materials using microwave plasma and the resulting products.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: A method for in-situ preparation of graphene-copper nanocluster composite materials using microwave plasma includes the following steps: (1) The copper salt solution is atomized into an aerosol, which is mixed with the carrier gas and acetylene gas to form a mixed reaction gas, which is then introduced into the microwave plasma reaction chamber to react and generate a primary composite powder of copper nanoclusters coated with graphene. (2) Transfer the graphene-coated copper nanocluster primary composite powder generated in step (1) to a tube furnace, introduce Ar-H2 mixed protective gas, heat to 200-300 °C, keep warm for 40-80 min, and then cool to room temperature to obtain the graphene-copper nanocluster composite material.

[0006] In the above-mentioned method for in-situ preparation of graphene-copper nanocluster composite materials by microwave plasma, preferably, in step (1), the concentration of the copper salt solution is 0.001-1.0 mol / L; the copper salt in the copper salt solution is at least one of copper nitrate, copper acetate, copper sulfate and copper chloride; and the solvent in the copper salt solution is at least one of deionized water, ethanol and ethylene glycol.

[0007] Preferably, in step (1), the carrier gas is at least one of argon, hydrogen, nitrogen or helium.

[0008] Preferably, in step (1), the volume fraction of the acetylene gas in the mixed reaction gas is 1% to 50%, and the volume fraction of the aerosol in the mixed reaction gas is 5% to 20%.

[0009] Preferably, in step (1), the copper salt solution is atomized into an aerosol using an ultrasonic atomizer or a gas-assisted atomizer, and the droplet diameter of the aerosol is 1 to 50 μm.

[0010] Preferably, in step (1), the flow rate of the mixed reaction gas is 100 to 1000 sccm.

[0011] Preferably, in step (1), the microwave operating frequency of the microwave plasma reaction cavity is 915 MHz or 2450 MHz, the microwave operating power is 3 to 100 kW, and the pressure inside the microwave plasma reaction cavity is 100 Pa to 10 kPa.

[0012] Preferably, in step (2), the volume ratio of Ar to H2 in the Ar-H2 mixed protective gas is (95-98):(2-5), and the flow rate is 50-100 sccm.

[0013] Preferably, in step (2), the heating rate is 5 to 10 °C / min, and the cooling rate to room temperature is ≤10 °C / min.

[0014] Based on a general inventive concept, the present invention also provides a graphene-copper nanocluster composite material obtained by the method described above, wherein the size of the copper core is 2 to 100 nm and the number of graphene shell layers is 1 to 10.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention integrates the three processes of copper salt reduction, copper nanocluster formation and graphene coating into a single step within a microwave plasma reaction zone, greatly simplifying the process flow, improving production efficiency, and avoiding contamination and agglomeration in intermediate steps.

[0016] 2. This invention uses solution atomization feeding, and the copper source is introduced in the form of atomically uniformly dispersed aerosol. Through precise premixing with acetylene, molecular-level uniform mixing of the reaction precursor is achieved, which is beneficial to forming a core-shell structure with uniform size and complete coating. Solution feeding also avoids the problems of clogging and uneven delivery of solid powder feeding.

[0017] 3. By precisely controlling the precursor concentration, gas ratio, plasma parameters, etc., this invention can effectively control the size of the copper core and the number of graphene shell layers, and the morphology and structure of the product are adjustable.

[0018] 4. This invention utilizes microwave plasma to provide a highly active environment, enabling the reaction to be completed instantaneously with low energy consumption. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a scanning electron microscope image of the graphene-copper nanocluster composite material of Example 1 of the present invention. Detailed Implementation

[0021] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0022] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0023] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0024] Example 1 A method for in-situ preparation of graphene-copper nanocluster composite materials using microwave plasma includes the following steps: (1) Preparation of precursor solution: Weigh copper nitrate and dissolve it in deionized water to prepare a copper salt solution with a concentration of 0.001 mol / L; (2) Plasma reaction: The copper salt solution prepared in step (1) is atomized into an aerosol using an ultrasonic atomizer, and the diameter of the aerosol droplets is controlled to be 1 μm; the aerosol is mixed with a carrier gas (pure argon) and acetylene gas to form a mixed reaction gas, wherein the volume fraction of acetylene gas in the mixed reaction gas is 1%, the volume fraction of aerosol in the mixed reaction gas is 5%, and the flow rate of the mixed reaction gas is 100 sccm; the mixed reaction gas is introduced into a microwave plasma reaction chamber, the microwave working frequency is set to 915 MHz, the microwave working power is 3 kW, and the pressure in the reaction chamber is controlled to be 100 Pa; the microwave plasma is excited to react and generate a primary composite powder of copper nanoclusters coated with graphene; at this time, the copper core size of the primary composite powder is about 2 nm and the number of graphene shell layers is about 1 layer. (3) Post-processing: The graphene-coated copper nanocluster primary composite powder generated in step (2) is transferred to a tube furnace and an Ar-H2 mixed protective gas (volume ratio 97:3) is introduced at a flow rate of 50 sccm; the temperature is raised to 200 ℃ at a heating rate of 5 ℃ / min and held for 40 min; then it is cooled to room temperature at a rate of 10 ℃ / min to obtain the graphene-copper nanocluster composite material.

[0025] The graphene-copper nanocluster composite material obtained in this embodiment was tested and found to be: Microstructure: Observed using scanning electron microscopy and transmission electron microscopy, such as... Figure 1 The copper core has a size of 2–5 nm, and the graphene shell has 1–2 layers.

[0026] Structural characterization: Raman spectroscopy shows I D / I G The ratio of 0.28 indicates that the graphene generated under low-energy conditions has very few defects and extremely high crystallinity, but the shell coverage may not be dense enough.

[0027] Physical properties: The measured conductivity is 3.8 × 10⁻⁶. 4 S / cm. Due to the extremely small size of the copper core, the interface scattering effect is significant, resulting in an overall conductivity slightly lower than that of samples with larger particle sizes.

[0028] Thermal stability: Thermogravimetric analysis results show that the oxidation onset temperature of this composite material is delayed by about 60°C compared with pure copper in an air atmosphere, indicating that the graphene layer effectively inhibits oxidation diffusion at high temperatures.

[0029] Example 2 A method for in-situ preparation of graphene-copper nanocluster composite materials using microwave plasma includes the following steps: (1) Preparation of precursor solution: Weigh copper chloride and dissolve it in ethanol to prepare a copper salt solution with a concentration of 1.0 mol / L; (2) Plasma reaction: The copper salt solution prepared in step (1) is atomized into an aerosol using a gas-assisted atomizer, and the diameter of the aerosol droplets is controlled to be 50 μm. The aerosol is mixed with a carrier gas (a mixture of hydrogen and nitrogen in a volume ratio of 1:10) and acetylene gas to form a mixed reaction gas, wherein the volume fraction of acetylene gas in the mixed reaction gas is 50%, the volume fraction of aerosol in the mixed reaction gas is 20%, and the flow rate of the mixed reaction gas is 100 sccm. The mixed reaction gas is introduced into a microwave plasma reaction chamber, and the microwave working frequency is set to 2450 MHz, the microwave working power is set to 100 kW, and the pressure in the reaction chamber is controlled to be 10 kPa. The microwave plasma is excited to react and generate a primary composite powder of copper nanoclusters coated with graphene. At this time, the copper core size of the primary composite powder is about 100 nm and the number of graphene shell layers is about 10 layers. (3) Post-processing: The graphene-coated copper nanocluster primary composite powder generated in step (2) is transferred to a tube furnace and Ar-H2 mixed protective gas (volume ratio 97:3) is introduced at a flow rate of 100 sccm; the temperature is raised to 300 ℃ at a heating rate of 10 ℃ / min and held for 80 min, and then cooled to room temperature by natural cooling (rate ≤10 ℃ / min) to obtain the graphene-copper nanocluster composite material.

[0030] The graphene-copper nanocluster composite material obtained in this embodiment was tested and found to be: Microstructure: Observed using scanning electron microscopy and transmission electron microscopy, the copper core size is 80-100 nm and the number of graphene shell layers is 8-10.

[0031] Structural characterization: Raman spectroscopy shows I D / I G The ratio is 0.45. While higher microwave power and reaction temperature promote the growth of multilayer graphene, they also introduce a small number of structural defects, leading to a relative increase in the intensity of the D peak.

[0032] Physical properties: The measured conductivity is 6.5 × 10⁻⁶. 4 S / cm. Despite the presence of a few defects, the overall conductivity is high due to the large copper core size reducing interface scattering and the multilayer graphene providing a good conductive pathway.

[0033] Thermal stability: Thermogravimetric analysis results show that the oxidation onset temperature of this composite material is delayed by about 60°C compared with pure copper in an air atmosphere, indicating that the graphene layer effectively inhibits oxidation diffusion at high temperatures.

[0034] Example 3 A method for in-situ preparation of graphene-copper nanocluster composite materials using microwave plasma includes the following steps: (1) Preparation of precursor solution: Weigh copper acetate and dissolve it in a mixture of ethylene glycol and deionized water (volume ratio 1:1) to prepare a copper salt solution with a concentration of 0.5 mol / L; (2) Plasma reaction: The copper salt solution prepared in step (1) is atomized into an aerosol using an ultrasonic atomizer, and the diameter of the aerosol droplets is controlled to be 25 μm; the aerosol is mixed with a carrier gas (helium) and acetylene gas to form a mixed reaction gas, wherein the volume fraction of acetylene gas in the mixed reaction gas is 25.5%, the volume fraction of aerosol in the mixed reaction gas is 10%, and the flow rate of the mixed reaction gas is 200 sccm; the mixed reaction gas is introduced into a microwave plasma reaction chamber, the microwave working frequency is set to 2450 MHz, the microwave working power is 50 kW, and the pressure in the reaction chamber is controlled to be 5 kPa; the microwave plasma is excited to react and generate a primary composite powder of copper nanoclusters coated with graphene; at this time, the copper core size of the primary composite powder is about 50 nm and the number of graphene shell layers is about 5 layers. (3) Post-processing: The graphene-coated copper nanocluster primary composite powder generated in step (2) is transferred to a tube furnace and Ar-H2 mixed protective gas (volume ratio 97:3) is introduced at a flow rate of 70 sccm; the temperature is raised to 250℃ at a heating rate of 8 ℃ / min and held for 60 min, and then cooled to room temperature at a rate of 5℃ / min to obtain the graphene-copper nanocluster composite material.

[0035] The graphene-copper nanocluster composite material obtained in this embodiment was tested and found to be: Microstructure: Observed using scanning electron microscopy and transmission electron microscopy, the copper core size is 45-55 nm and the number of graphene shell layers is 4-6.

[0036] Structural characterization: Raman spectroscopy shows I D / I G With a ratio of 0.35, the graphene exhibits good crystallinity, and the defect density and number of layers achieve a good balance.

[0037] Physical properties: The measured conductivity is 5.8 × 10⁻⁶. 4 S / cm. The material prepared under these process conditions achieves an excellent balance between particle size uniformity and electrical conductivity.

[0038] Thermal stability: Thermogravimetric analysis results show that the oxidation onset temperature of this composite material is delayed by about 80°C compared with pure copper in an air atmosphere, indicating that the graphene layer effectively inhibits oxidation diffusion at high temperatures.

[0039] Example 4 A method for in-situ preparation of graphene-copper nanocluster composite materials using microwave plasma includes the following steps: (1) Preparation of precursor solution: Weigh copper sulfate and dissolve it in pure ethanol to prepare a copper salt solution with a concentration of 0.1 mol / L; (2) Plasma reaction: The copper salt solution prepared in step (1) is atomized into an aerosol using a gas-assisted atomizer, and the diameter of the aerosol droplets is controlled to be 10 μm; the aerosol is mixed with a carrier gas (pure nitrogen) and acetylene gas to form a mixed reaction gas, wherein the volume fraction of acetylene gas in the mixed reaction gas is 1%, the volume fraction of aerosol in the mixed reaction gas is 5%, and the flow rate of the mixed reaction gas is 1000 sccm; the mixed reaction gas is introduced into a microwave plasma reaction chamber, the microwave working frequency is set to 915 MHz, the microwave working power is 20 kW, and the pressure in the reaction chamber is controlled to be 1 kPa; the microwave plasma is excited to react and generate a primary composite powder of copper nanoclusters coated with graphene; at this time, the core size of the primary composite powder is about 15 nm and the graphene shell layer is about 3 layers. (3) Post-processing: The graphene-coated copper nanocluster primary composite powder generated in step (2) is transferred to a tube furnace and an Ar-H2 mixed protective gas (volume ratio 97:3) is introduced at a flow rate of 60 sccm; the temperature is raised to 220 ℃ at a heating rate of 6 ℃ / min and held for 50 min; then it is cooled to room temperature at a rate of 8 ℃ / min to obtain the graphene-copper nanocluster composite material.

[0040] The graphene-copper nanocluster composite material obtained in this embodiment was tested and found to be: Microstructure: Observed using scanning electron microscopy and transmission electron microscopy, the copper core size is 15-25 nm and the number of graphene shell layers is 2-4.

[0041] Structural characterization: Raman spectroscopy shows I D / I G A ratio of 0.32 indicates that the graphene has good crystallinity and a complete structure.

[0042] Physical properties: The measured conductivity is 5.2 × 10⁻⁶. 4 S / cm. This example can produce a composite material with excellent overall electrical properties.

[0043] Thermal stability: Thermogravimetric analysis results show that the oxidation onset temperature of this composite material is delayed by about 80°C compared with pure copper in an air atmosphere, indicating that the graphene layer effectively inhibits oxidation diffusion at high temperatures.

Claims

1. A method for in-situ preparation of graphene-copper nanocluster composite materials using microwave plasma, characterized in that, Includes the following steps: (1) The copper salt solution is atomized into an aerosol, which is mixed with the carrier gas and acetylene gas to form a mixed reaction gas, which is then introduced into the microwave plasma reaction chamber to react and generate a primary composite powder of copper nanoclusters coated with graphene. (2) Transfer the graphene-coated copper nanocluster primary composite powder generated in step (1) to a tube furnace, introduce Ar-H2 mixed protective gas, heat to 200-300 °C, keep warm for 40-80 min, and then cool to room temperature to obtain the graphene-copper nanocluster composite material.

2. The method for in-situ preparation of graphene-copper nanoclusters composite material using microwave plasma according to claim 1, characterized in that, In step (1), the concentration of the copper salt solution is 0.001 to 1.0 mol / L; the copper salt in the copper salt solution is at least one of copper nitrate, copper acetate, copper sulfate and copper chloride; the solvent in the copper salt solution is at least one of deionized water, ethanol and ethylene glycol.

3. The method for in-situ preparation of graphene-copper nanoclusters composite material using microwave plasma according to claim 1, characterized in that, In step (1), the carrier gas is at least one of argon, hydrogen, nitrogen or helium.

4. The method for in-situ preparation of graphene-copper nanocluster composite materials using microwave plasma according to claim 1, characterized in that, In step (1), the volume fraction of the acetylene gas in the mixed reaction gas is 1% to 50%, and the volume fraction of the aerosol in the mixed reaction gas is 5% to 20%.

5. The method for in-situ preparation of graphene-copper nanoclusters composite material using microwave plasma according to claim 1, characterized in that, In step (1), the copper salt solution is atomized into an aerosol using an ultrasonic atomizer or a gas-assisted atomizer, and the droplet diameter of the aerosol is 1 to 50 μm.

6. The method for in-situ preparation of graphene-copper nanocluster composite materials using microwave plasma according to claim 1, characterized in that, In step (1), the flow rate of the mixed reaction gas is 100 to 1000 sccm.

7. The method for in-situ preparation of graphene-copper nanocluster composite materials using microwave plasma according to claim 1, characterized in that, In step (1), the microwave operating frequency of the microwave plasma reaction cavity is 915 MHz or 2450 MHz, the microwave operating power is 3 to 100 kW, and the pressure inside the microwave plasma reaction cavity is 100 Pa to 10 kPa.

8. The method for in-situ preparation of graphene-copper nanoclusters composite material by microwave plasma according to claim 1, characterized in that, In step (2), the volume ratio of Ar to H2 in the Ar-H2 mixed protective gas is (95-98):(2-5), and the flow rate is 50-100 sccm.

9. The method for in-situ preparation of graphene-copper nanocluster composite materials using microwave plasma according to claim 1, characterized in that, In step (2), the heating rate is 5 to 10 °C / min, and the cooling rate to room temperature is ≤10 °C / min.

10. A graphene-copper nanocluster composite material obtained by the method according to any one of claims 1 to 9, characterized in that, In the graphene-copper nanocluster composite material, the size of the copper core is 2 to 100 nm, and the number of graphene shell layers is 1 to 10.

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