Preparation method of high-uniformity super-dispersed nanometer hollow ball copper powder

Abstract

The application discloses a preparation method of high-uniformity super-dispersed nanometer hollow ball copper powder, and belongs to the technical field of nanometer material preparation. The method comprises the following steps: under the protection of inert gas, uniformly nanometer liquid drops are formed through microwave heating and ultrasonic atomization of a copper salt solution, and high-temperature pyrolysis is performed; during the high-temperature pyrolysis process, a mixed atmosphere of inert gas and reducing gas is adopted to ensure the reduction of copper particles and the hollow ball morphology; and the powder after pyrolysis is captured by using high-purity water containing a dispersant and a reducing agent to further prevent oxidation. The prepared hollow ball nanometer copper powder has the advantages of uniform particle size, one-time particle average particle size of 10-20 nanometers, secondary particle average particle size of 100-300 nanometers, regular morphology, uniformity, high purity and the like, and is suitable for fields of high-performance batteries, catalysts and electronic materials and the like. The method has the advantages of simple process, low cost, continuous in-out and strong expandability, and has significant industrial application value.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial preparation technology, specifically to a method for preparing hollow hydrangea nano-copper powder based on microwave heating, ultrasonic atomization and high-temperature pyrolysis processes. Background Technology

[0002] Copper powder, as an important functional metallic material, is widely used in fields such as electronic conductive pastes, catalysts, thermally conductive interface materials, and 3D printing. In recent years, nanoscale hollow copper powder has become a research hotspot due to its high specific surface area, low density, excellent electromagnetic wave absorption properties, and catalytic activity. However, existing preparation techniques still have significant shortcomings, restricting its industrial application.

[0003] Traditional copper powder preparation mainly adopts mechanical ball milling, chemical reduction and template method: (1) Mechanical ball milling breaks copper ingots by high-energy collision. Although the equipment is simple, it is easy to introduce lattice defects, resulting in a large range of particle size distribution. (2) Chemical reduction uses copper sulfate / copper nitrate as precursor and hydrazine hydrate, ascorbic acid and other reducing agents to reduce copper powder in the liquid phase. However, the product is easy to agglomerate and has poor dispersibility. The morphology is difficult to control, and solid particles or irregular polyhedra are generated. The hollow structure rate is <10%. The residual reducing agent leads to low purity (≥98%) and other disadvantages. (3) Template method uses PS microspheres, SiO2 and other templates. After copper plating on the surface, the template is removed to obtain hollow copper powder. However, template removal requires strong acid / strong alkali, which destroys the integrity of the copper shell. The process is complicated, the cost is high, and it is difficult to scale up. The product wall thickness is uneven and the sphericity is low.

[0004] Current technical challenges are concentrated in the following aspects: it is difficult to simultaneously achieve a nanoscale hollow structure and a hydrangea-like surface with nanoscale roughness; strong van der Waals forces between particles lead to poor dispersion uniformity under uncoated conditions; existing processes are highly dependent on equipment precision and have poor batch stability. Given the problems of uneven particle size, irregular morphology, and poor dispersibility in traditional copper powder preparation methods, as well as the complexity and high cost of these processes, developing an efficient, low-cost method for preparing hollow hydrangea-shaped copper nanoparticles with high uniformity and excellent dispersibility is of great significance. Summary of the Invention

[0005] This invention provides a method for preparing highly uniform and ultradispersed hollow hydrangea copper powder based on microwave heating, ultrasonic atomization and high-temperature pyrolysis. The oxygen content is controlled throughout the process to ensure the high purity of the copper powder, the hollow hydrangea morphology and the nanoscale size. The method of this invention has the advantages of simple process, low cost and strong scalability, and is suitable for large-scale industrial production.

[0006] The technical solution of this invention is as follows:

[0007] A method for preparing highly uniform and ultradispersed nano-hollow hydrangea copper powder, the specific steps of which are as follows:

[0008] (1) Dissolve soluble copper salt in deionized water to prepare copper salt solution, and add structure control agent at the same time. During the preparation process, argon gas is introduced to remove oxygen in the solution. After adjusting the pH value of copper salt solution to 3.0-6.5, the solution is degassed to form a homogeneous solution.

[0009] (2) The copper salt solution is transferred to a closed reactor to maintain an oxygen-free environment. After microwave treatment, the solution is transferred to an ultrasonic atomizing device for ultrasonic atomization. The atomized droplet size is 5-20 micrometers.

[0010] (3) The atomized droplets are transported to a high-temperature pyrolysis furnace for high-temperature pyrolysis;

[0011] (4) After pyrolysis, high-purity water containing dispersant and reducing agent is used for collection. After collection, the product is separated and washed multiple times with deionized water and ethanol. After drying, the washed product is packaged to obtain hollow hydrangea nano copper powder.

[0012] Step (1) Soluble copper salts include copper sulfate, copper nitrate, copper chloride, copper formate, copper acetate, copper perchlorate, and copper bromide; the concentration of the copper salt solution is 0.05-3.00 mol / L.

[0013] Step (1) The structure control agent is a mixture of polyethylene glycol and sodium citrate, with a mass ratio of polyethylene glycol to sodium citrate of 1:0.5-1:3; the mass of the soluble copper salt is more than 7 times that of the structure control agent.

[0014] Step (1) Adjust the pH value of the copper salt solution using weak acids such as acetic acid, citric acid, oxalic acid, phosphoric acid, carbonic acid, and formic acid.

[0015] Step (2) Maintaining an anaerobic environment involves continuously introducing inert gas or adding a deoxidizer. Inert gases include nitrogen, argon, etc.; deoxidizers include ascorbic acid, hydrazine hydrate, BHJ, etc. The amount of deoxidizer added is 8-10 g / L copper salt solution.

[0016] Step (2) The microwave treatment power is 500-1000W / L of solution, the treatment time is 1-30 minutes, and the treatment temperature is 80-90℃.

[0017] Step (2) Ultrasonic atomization uses inert gas as the atomization medium, including nitrogen, argon, etc. The ultrasonic frequency is 20-40kHz and the atomization pressure is 0.1-0.5MPa.

[0018] Step (3) High-temperature pyrolysis uses a mixture of hydrogen and inert gases as a protective atmosphere, wherein the hydrogen gas fraction is 5-20%, and the inert gases include nitrogen and argon. The pyrolysis temperature is 400-980℃ and the pyrolysis time is 1-300 seconds.

[0019] Step (4) The concentration of the dispersant in the high-purity water containing the dispersant and reducing agent is 0.1-5.0 wt%, and the dispersant includes, but is not limited to, CTAB, SDS, PVP, etc.

[0020] Step (4) The reducing agent is hydrazine hydrate, and the concentration of the reducing agent in the high-purity water containing the dispersant and the reducing agent is 0.05-0.2 mol / L.

[0021] The final copper nanoparticles obtained by this invention have a three-dimensional hydrangea-like morphology with a sphere diameter of 100-500 nm and a surface composed of self-assembled nanosheets with a thickness of 10-30 nm, resulting in a specific surface area of ​​10-40 m² / g.

[0022] The beneficial effects of this invention are:

[0023] The hollow hydrangea nano-copper powder prepared by this invention has the advantages of uniform particle size, regular morphology, and high purity, and is suitable for high-performance batteries, catalysts, and magnetic materials.

[0024] This invention significantly reduces the oxidation level of copper powder by controlling the oxygen content throughout the entire process, thereby improving its performance and application value.

[0025] The method of this invention has the advantages of simple process, continuous input and output, low cost and strong scalability, and is suitable for large-scale industrial production. Attached Figure Description

[0026] Figure 1 SEM image of the highly uniform, ultradispersed nano-hollow hydrangea copper powder prepared in Example 1;

[0027] Figure 2 SEM images of the highly uniform, ultradispersed nano-hollow hydrangea copper powder prepared in Example 1 at different magnifications;

[0028] Figure 3 The image shows the particle size distribution of the highly uniform, ultradispersed nano-hollow hydrangea copper powder prepared in Example 1.

[0029] Figure 4 This is a schematic diagram of the morphology of a single copper powder prepared in Example 1. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments.

[0031] Example 1

[0032] (1) Dissolve 12.1g of copper nitrate in 200mL of deionized water to prepare a copper nitrate solution. Add 0.5g of polyethylene glycol / sodium citrate composite structure control agent (polyethylene glycol and sodium citrate in a mass ratio of 1:1). During the preparation process, argon gas is introduced to remove oxygen from the solution. Citric acid is added to adjust the pH value to 4.0. Argon gas is introduced for 20min to remove oxygen from the solution.

[0033] (2) Transfer the copper salt solution to a closed reactor protected by argon gas to maintain an oxygen-free environment. Microwave treat the solution by heating it to 80°C with a microwave power of 500W / L solution and maintaining it for 15 minutes. Then transfer it to an ultrasonic atomizing device for ultrasonic atomization. Argon gas is used as the carrier gas for atomization (atomization pressure is 0.1MPa) and the ultrasonic frequency is 20kHz.

[0034] (3) The atomized droplets are transported to a 650℃ high-temperature pyrolysis furnace for high-temperature pyrolysis. The high-temperature pyrolysis is carried out in an H2 / Ar mixed atmosphere with a hydrogen gas integral of 10% for 5 seconds.

[0035] (4) The powder after the pyrolysis reaction was collected using high-purity water containing dispersant PVP and reducing agent hydrazine hydrate, wherein the mass concentration of PVP was 0.5% and the concentration of hydrazine hydrate was 0.1 mol / L. After collection, the product was separated and washed multiple times with deionized water and ethanol. After drying, the washed product was packaged to obtain hollow hydrangea nano copper powder.

[0036] like Figure 1 , Figure 2 , Figure 3 and Figure 4 The image shows the microstructure, particle size distribution, and morphology of individual copper powder particles of hollow hydrangea nanoparticles prepared in the example. Figure 1 , Figure 2 , Figure 4 The prepared copper powder is generally composed of uniform hollow hydrangeas with a diameter of 100-500 nm. The surface is composed of self-assembled nanosheets with a thickness of 10-30 nm. This indicates that the method of this invention can successfully synthesize high-quality hollow hydrangea copper powder. The prepared copper powder has good overall dispersibility with almost no agglomeration. This may be due to the surface tension between droplets during high-temperature pyrolysis, which causes partial fusion of adjacent droplets during evaporation, leading to agglomeration of some particles. The particle size of the prepared copper powder was statistically analyzed. Figure 3 The prepared secondary particles exhibit a normal particle size distribution with a narrow range, indicating good consistency of the copper powder prepared by this invention. BET testing revealed a specific surface area of ​​36.6 m². 2 / g can serve as an ideal support for catalysts.

[0037] Example 2

[0038] (1) Dissolve 18.2g of copper acetate in 200mL of deionized water to prepare a copper acetate solution. Add 1.2g of polyethylene glycol / sodium citrate composite structure control agent (polyethylene glycol and sodium citrate in a mass ratio of 1:2). During the preparation process, nitrogen gas is introduced to remove oxygen from the solution. Oxalic acid is added to adjust the pH value to 3.0. Argon gas is introduced for 20min to remove oxygen from the solution.

[0039] (2) Transfer the copper salt solution to a closed reactor protected by argon gas to maintain an oxygen-free environment. Microwave treat the solution by heating it to 90°C with a microwave power of 900W / L solution and maintaining it for 10 minutes. Then transfer it to an ultrasonic atomizing device for ultrasonic atomization. Argon gas is used as the carrier gas for atomization (atomization pressure is 0.2MPa) and the ultrasonic frequency is 40kHz.

[0040] (3) The atomized droplets are transported to a 980℃ high-temperature pyrolysis furnace for high-temperature pyrolysis. The high-temperature pyrolysis is carried out in an H2 / Ar mixed atmosphere with a hydrogen gas integral of 20% for 2 seconds.

[0041] (4) The powder after the pyrolysis reaction was collected using high-purity water containing dispersant CTAB and reducing agent hydrazine hydrate, wherein the mass concentration of CTAB was 5% and the concentration of hydrazine hydrate was 0.2 mol / L. After collection, the product was separated and washed multiple times with deionized water and ethanol. After drying, the washed product was packaged to obtain hollow hydrangea nano copper powder.

[0042] Example 3

[0043] (1) Dissolve 22.3g of copper bromide in 200mL of deionized water to prepare a copper bromide solution. Add 0.3g of polyethylene glycol / sodium citrate composite structure control agent (polyethylene glycol and sodium citrate in a mass ratio of 1:0.5). During the preparation process, argon gas is introduced to remove oxygen from the solution. Oxalic acid is added to adjust the pH value to 3.8. Argon gas is introduced for 30min to remove oxygen from the solution.

[0044] (2) Transfer the copper salt solution to a closed reactor protected by argon gas to maintain an oxygen-free environment. Microwave treat the solution by heating it to 80°C with a microwave power of 500W / L solution and maintaining it for 30 minutes. Then transfer it to an ultrasonic atomizing device for ultrasonic atomization. Argon gas is used as the carrier gas for atomization (atomization pressure is 0.3MPa) and the ultrasonic frequency is 20kHz.

[0045] (3) The atomized droplets are transported to a 400℃ high-temperature pyrolysis furnace for high-temperature pyrolysis. The high-temperature pyrolysis is carried out in an H2 / Ar mixed atmosphere with a hydrogen gas integral of 5% for 5 seconds.

[0046] (4) The powder after the pyrolysis reaction was collected using high-purity water containing dispersant SDS and reducing agent hydrazine hydrate, wherein the mass concentration of SDS was 0.1% and the concentration of hydrazine hydrate was 0.05 mol / L. After collection, the product was separated and washed multiple times with deionized water and ethanol. After drying, the washed product was packaged to obtain hollow hydrangea nano copper powder.

[0047] Example 4

[0048] (1) Dissolve 13.4g of copper chloride and 12.4g of copper sulfate in 200mL of deionized water to prepare a mixed copper salt solution. Add 1.5g of polyethylene glycol / sodium citrate composite structure control agent (polyethylene glycol and sodium citrate in a mass ratio of 1:3), add carbonic acid to adjust the pH value to 6.5, and add hydrazine hydrate with a final concentration of 10g / L as a deoxidizer.

[0049] (2) Transfer the copper salt solution to a closed reactor protected by argon gas to maintain an oxygen-free environment. Microwave treat the solution by heating it to 88°C with a microwave power of 1000W / L solution and maintaining it for 1 minute. Then transfer it to an ultrasonic atomizing device for ultrasonic atomization. Argon gas is used as the carrier gas for atomization (atomization pressure is 0.5MPa) and the ultrasonic frequency is 40kHz.

[0050] (3) The atomized droplets are transported to a 750℃ high-temperature pyrolysis furnace for high-temperature pyrolysis. The high-temperature pyrolysis is carried out in an H2 / Ar mixed atmosphere with a hydrogen gas integral of 15% for 2 seconds.

[0051] (4) The powder after the pyrolysis reaction was collected using high-purity water containing dispersant PVP and reducing agent hydrazine hydrate, wherein the mass concentration of PVP was 2% and the concentration of hydrazine hydrate was 0.05 mol / L. After collection, the product was separated and washed multiple times with deionized water and ethanol. After drying, the washed product was packaged to obtain hollow hydrangea nano copper powder.

[0052] Example 5

[0053] (1) Dissolve 18.6g of copper perchlorate in 200mL of deionized water to prepare a copper perchlorate solution. Add 0.8g of polyethylene glycol / sodium citrate composite structure control agent (polyethylene glycol and sodium citrate in a mass ratio of 1:1). During the preparation process, nitrogen gas is introduced to remove oxygen from the solution. Oxalic acid is added to adjust the pH value to 5. Nitrogen gas is introduced for 30min to remove oxygen from the solution.

[0054] (2) Transfer the copper salt solution to a closed reactor protected by argon gas to maintain an oxygen-free environment. Microwave treat the solution by heating it to 85°C with a microwave power of 700W / L solution and maintaining it for 25 minutes. Then transfer it to an ultrasonic atomizing device for ultrasonic atomization. Argon gas is used as the carrier gas for atomization (atomization pressure is 0.2MPa) and the ultrasonic frequency is 30kHz.

[0055] (3) The atomized droplets are transported to a 580℃ high-temperature pyrolysis furnace for high-temperature pyrolysis. The high-temperature pyrolysis is carried out in an H2 / Ar mixed atmosphere with a hydrogen gas integral of 8% for 300 seconds.

[0056] (4) The powder after the pyrolysis reaction was collected using high-purity water containing dispersant CTAB and reducing agent hydrazine hydrate, wherein the mass concentration of CTAB was 1% and the concentration of hydrazine hydrate was 0.05 mol / L. After collection, the product was separated and washed multiple times with deionized water and ethanol. After drying, the washed product was packaged to obtain hollow hydrangea nano copper powder.

[0057] Example 6

[0058] (1) Dissolve 15.6g of copper formate in 200mL of deionized water to prepare a copper formate solution, add 2.0g of polyethylene glycol / sodium citrate composite structure control agent (polyethylene glycol and sodium citrate in a mass ratio of 1:1.5), add acetic acid to adjust the pH value to 4.5, and add ascorbic acid with a final concentration of 8g / L as a deoxygenating agent.

[0059] (2) The copper salt solution was transferred to a closed reactor protected by argon gas to maintain an oxygen-free environment. The solution was microwave treated and heated to 82°C with a microwave power of 600W / L solution. After maintaining the temperature for 20 minutes, the solution was transferred to an ultrasonic atomizing device for ultrasonic atomization. Argon gas was used as the carrier gas for atomization (atomization pressure was 0.3MPa) and the ultrasonic frequency was 25kHz.

[0060] (3) The atomized droplets are transported to a 900℃ high-temperature pyrolysis furnace for high-temperature pyrolysis. The high-temperature pyrolysis is carried out in an H2 / Ar mixed atmosphere with a hydrogen gas integral of 18% for 1 second.

[0061] (4) The powder after the pyrolysis reaction was collected using high-purity water containing dispersant SDS and reducing agent hydrazine hydrate, wherein the mass concentration of SDS was 3% and the concentration of hydrazine hydrate was 0.15 mol / L. After collection, the product was separated and washed multiple times with deionized water and ethanol. After drying, the washed product was packaged to obtain hollow hydrangea nano copper powder.

[0062] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing highly uniform, ultra-dispersed nano-hollow hydrangea copper powder, characterized in that, The specific steps are as follows: (1) Dissolve soluble copper salt in deionized water to prepare copper salt solution, and add structure control agent at the same time. During the preparation process, argon gas is introduced to remove oxygen in the solution, adjust the pH value of copper salt solution to 3.0-6.5, and then degas the solution. The structure control agent is a mixture of polyethylene glycol and sodium citrate, with a mass ratio of polyethylene glycol to sodium citrate of 1:0.5-1:3; the mass of the soluble copper salt is more than 7 times that of the structure control agent. (2) Transfer the copper salt solution to a closed reactor, maintain an oxygen-free environment, and then microwave the solution and atomize it with ultrasound. (3) The ultrasonically atomized droplets are subjected to high-temperature pyrolysis; (4) After pyrolysis, high-purity water containing dispersant and reducing agent is used for collection. After collection, the product is separated and washed multiple times with deionized water and ethanol. After drying, the washed product is packaged to obtain hollow hydrangea-shaped copper nanopowder. The copper nanopowder has a three-dimensional hydrangea-shaped morphology with a sphere diameter of 100-500 nm and a surface composed of self-assembled nanosheets with a thickness of 10-30 nm.

2. The method for preparing highly uniform, ultra-dispersed nano-hollow hydrangea copper powder according to claim 1, characterized in that, Step (1) Soluble copper salts include copper sulfate, copper nitrate, copper chloride, copper formate, copper acetate, copper perchlorate, and copper bromide.

3. The method for preparing highly uniform, ultra-dispersed nano-hollow hydrangea copper powder according to claim 1, characterized in that, Step (2) Maintaining an anaerobic environment involves continuously introducing an inert gas or adding a deoxidizer. The inert gas includes nitrogen or argon; the deoxidizer includes ascorbic acid, hydrazine hydrate, and BHJ. The amount of deoxidizer added is 8-10 g / L of copper salt solution.

4. The method for preparing highly uniform, ultra-dispersed nano-hollow hydrangea copper powder according to claim 1, characterized in that, Step (2) The microwave treatment power is 500-1000W / L of solution, the treatment time is 1-30 minutes, and the treatment temperature is 80-90℃.

5. The method for preparing highly uniform, ultra-dispersed nano-hollow hydrangea copper powder according to claim 1, characterized in that, Step (2) Ultrasonic atomization uses inert gas as the atomization medium, including nitrogen and argon. The ultrasonic frequency is 20-40kHz and the atomization pressure is 0.1-0.5MPa.

6. The method for preparing highly uniform, ultra-dispersed nano-hollow hydrangea copper powder according to claim 1, characterized in that, Step (3) High-temperature pyrolysis uses a mixture of hydrogen and inert gases as a protective atmosphere, wherein the hydrogen gas fraction is 5-20%, and the inert gases include nitrogen and argon. The pyrolysis temperature is 400-980℃ and the pyrolysis time is 1-300 seconds.

7. The method for preparing highly uniform, ultra-dispersed nano-hollow hydrangea copper powder according to claim 1, characterized in that, Step (4) The dispersant includes, but is not limited to, CTAB, SDS, and PVP, and the mass concentration of the dispersant is 0.1-5.0%.

8. The method for preparing highly uniform, ultra-dispersed nano-hollow hydrangea copper powder according to claim 1, characterized in that, In step (4), the reducing agent is hydrazine hydrate, and the concentration of the reducing agent is 0.05-0.2 mol / L.

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