Preparation method of high-uniformity ultra-dispersion nano hollow hydrangea copper powder

Abstract

The invention discloses a preparation method of high-uniformity ultra-dispersion nano hollow hydrangea copper powder, and belongs to the technical field of nano material preparation, and the method comprises the following steps: forming uniform nano-scale liquid drops from a copper salt solution through microwave heating and ultrasonic atomization under the protection of inert gas, and performing high-temperature pyrolysis to obtain high-uniformity ultra-dispersion nano hollow hydrangea copper powder; in the high-temperature pyrolysis process, the mixed atmosphere of inert gas and reducing gas is adopted, reduction of copper particles and the shape of the hollow hydrangea are ensured, the pyrolyzed powder is captured with high-purity water containing a dispersing agent and a reducing agent, oxidation is further prevented, and the prepared hollow hydrangea nano-copper powder has the advantages of being uniform in particle size, high in particle size and good in stability. The method has the advantages that the average particle size of primary particles is 10-20 nanometers, the average particle size of secondary particles is 100-300 nanometers, the morphology is regular, the uniformity is consistent, the purity is high and the like, the method is suitable for the fields of high-performance batteries, catalysts, electronic materials and the like, and the method is simple in process, low in cost, continuous in and out, high in expandability and remarkable in industrial application value.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterial preparation, and in particular to a method for preparing hollow hydrangea nano-copper powder based on microwave heating, ultrasonic atomization and high-temperature pyrolysis processes. Background Art

[0002] Copper powder, as an important functional metal material, is widely used in electronic conductive pastes, catalysts, thermal interface materials, 3D printing, and other fields. In recent years, nanoscale hollow copper powders have become a cutting-edge research hotspot due to their high specific surface area, low density, excellent electromagnetic wave absorption properties, and catalytic activity. However, existing preparation technologies still have significant limitations, hindering their industrial application.

[0003] Traditional copper powder preparation mainly adopts mechanical ball milling, chemical reduction and template method: (1) Mechanical ball milling crushes copper ingots through high-energy collision. Although the equipment is simple, it is easy to introduce lattice defects, resulting in a large span of particle size distribution; (2) Chemical reduction method uses copper sulfate / copper nitrate as precursor and hydrazine hydrate, ascorbic acid, etc. as reducing agent to reduce and obtain copper powder in liquid phase, but there are disadvantages such as easy agglomeration of products and poor dispersion; difficult to control morphology, mostly solid particles or irregular polyhedrons are generated, and the hollow structure rate is <10%; the residual reducing agent leads to low purity (≥98%); (3) Template method uses PS microspheres, SiO2, etc. as templates, and removes the template after copper plating to obtain hollow copper powder, but template removal requires strong acid / strong alkali, which destroys the integrity of the copper shell layer; the process is complex, costly and difficult to scale up; the product wall thickness is uneven and the sphericity is low.

[0004] Current technical difficulties primarily focus on achieving both a nanoscale hollow structure and a hydrangea-like surface nanoroughness; strong interparticle van der Waals forces, resulting in poor dispersion uniformity without coating; and existing processes, which rely heavily on equipment precision and suffer from poor batch stability. Given that traditional copper powder preparation methods suffer from uneven particle size, irregular morphology, and poor dispersion, as well as complex processes and high costs, developing an efficient, low-cost method for preparing hollow hydrangea-like nano-copper powders with high uniformity and excellent dispersion is crucial. Summary of the Invention

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

[0006] The technical solutions of the present invention are as follows: A method for preparing highly uniform and ultra-dispersed nano hollow hydrangea copper powder, the specific steps are as follows: (1) A soluble copper salt is dissolved in deionized water to prepare a copper salt solution, and a structure control agent is added. During the preparation process, argon gas is introduced to remove oxygen from the solution. After adjusting the pH value of the copper salt solution to 3.0-6.5, the solution is degassed to form a homogeneous solution; (2) The copper salt solution is transferred to a closed reactor, maintained in an oxygen-free environment, subjected to microwave treatment, and then transferred to an ultrasonic atomization device for ultrasonic atomization, with the atomized droplet size being 5-20 μm; (3) transporting the atomized droplets to a high-temperature pyrolysis furnace for high-temperature pyrolysis; (4) After the pyrolysis is completed, high-purity water containing a dispersant and a reducing agent is used for capture. The product is separated after capture and washed multiple times with deionized water and ethanol. The washed product is dried and encapsulated to obtain hollow hydrangea nano-copper powder.

[0007] In step (1), the soluble copper salt includes 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.

[0008] In step (1), the structure control agent is a mixture of polyethylene glycol and sodium citrate, wherein the mass ratio of polyethylene glycol to sodium citrate in the mixture is 1:0.5-1:3; and the mass of the soluble copper salt is more than 7 times that of the structure control agent.

[0009] In step (1), the pH value of the copper salt solution is adjusted by using a weak acid such as acetic acid, citric acid, oxalic acid, phosphoric acid, carbonic acid, or formic acid.

[0010] In step (2), the oxygen-free environment is maintained by continuously introducing an inert gas or placing a deoxidizer. The inert gas includes nitrogen, argon, etc.; the deoxidizer includes ascorbic acid, hydrazine hydrate, BHJ, etc., and the amount of the deoxidizer added is 8-10 g / L copper salt solution.

[0011] The power of the microwave treatment in step (2) is 500-1000 W / L solution, the treatment time is 1-30 minutes, and the treatment temperature is 80-90°C.

[0012] In step (2), ultrasonic atomization uses an inert gas as the atomization medium. The inert gas includes nitrogen, argon, etc. The ultrasonic frequency is 20-40 kHz and the atomization pressure is 0.1-0.5 MPa.

[0013] Step (3) high-temperature pyrolysis uses a mixed gas of hydrogen and inert gas as the protective atmosphere, wherein the volume fraction of hydrogen is 5-20%, and the inert gas includes nitrogen and argon. The pyrolysis temperature is 400-980°C and the pyrolysis time is 1-300 seconds.

[0014] In step (4), the concentration of the dispersant in the high-purity water containing the dispersant and the reducing agent is 0.1-5.0 wt %. The dispersant includes but is not limited to CTAB, SDS, PVP, etc.

[0015] The reducing agent in step (4) 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.

[0016] The nano copper powder finally obtained by the present invention has a three-dimensional hydrangea-like morphology, a sphere diameter of 100-500nm, a surface composed of self-assembled nanosheets with a thickness of 10-30nm, and a specific surface area of ​​10-40m² / g.

[0017] Beneficial effects of the present invention: The hollow hydrangea nano copper powder prepared by the present invention has the advantages of uniform particle size, regular morphology, high purity, etc., and is suitable for the fields of high-performance batteries, catalysts, magnetic materials, etc.

[0018] The present invention significantly reduces the oxidation degree of copper powder by controlling the oxygen content throughout the entire process, thereby improving the performance and application value of the copper powder.

[0019] The method of the present invention has the advantages of simple process, continuous input and output, low cost, strong scalability, etc., and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is an SEM image of the highly uniform and ultra-dispersed nano hollow hydrangea copper powder prepared in Example 1; Figure 2 The SEM images of the highly uniform and ultra-dispersed nano hollow hydrangea copper powder prepared in Example 1 at different magnifications are shown; Figure 3 This is the particle size distribution image of the highly uniform and ultra-dispersed nano hollow hydrangea copper powder prepared in Example 1; Figure 4 Schematic diagram of the morphology of a single copper powder prepared in Example 1. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to specific embodiments.

[0022] Example 1 (1) Dissolve 12.1 g of copper nitrate in 200 mL of deionized water to prepare a copper nitrate solution. Add 0.5 g of a 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 was introduced to remove oxygen from the solution. Citric acid was added to adjust the pH to 4.0. Argon gas was introduced for 20 minutes to remove oxygen from the solution. (2) The copper salt solution was transferred to a closed reactor protected by argon to maintain an oxygen-free environment. The solution was microwave-treated and heated to 80°C at a microwave power of 500 W / L solution. After maintaining for 15 minutes, it was transferred to an ultrasonic atomization device for ultrasonic atomization. Argon was used as the carrier gas for atomization (atomization pressure of 0.1 MPa) and the ultrasonic frequency was 20 kHz. (3) The atomized droplets are transported to a 650°C high-temperature pyrolysis furnace for high-temperature pyrolysis. The high-temperature pyrolysis is carried out in a H2 / Ar mixed atmosphere with a hydrogen volume fraction of 10% for 5 seconds; (4) The powder after the pyrolysis reaction was captured using high-purity water containing a dispersant PVP and a reducing agent hydrazine hydrate, wherein the mass concentration of PVP was 0.5% and the concentration of hydrazine hydrate was 0.1 mol / L. The product was separated after capture and washed with deionized water and ethanol multiple times. The washed product was dried and encapsulated to obtain hollow hydrangea nano-copper powder.

[0023] like Figure 1 、 Figure 2 、 Figure 3 and Figure 4 The figure shows the microstructure, particle size distribution and single copper powder particle morphology of the hollow hydrangea nano-copper powder prepared in the embodiment. Figure 1 、 Figure 2 、 Figure 4 The prepared copper powder is generally uniform hollow hydrangeas with a sphere diameter of 100-500nm and a surface composed of self-assembled nanosheets with a thickness of 10-30nm. This shows that the method of the present invention can successfully synthesize high-quality hollow hydrangea copper powder. The prepared copper powder has good overall dispersion and almost no agglomeration phenomenon is found. This may be because the surface tension between the droplets during the high-temperature pyrolysis process causes the adjacent droplets to partially fuse during the evaporation process, resulting in the agglomeration of some particles. The particle size of the prepared copper powder is statistically analyzed. Figure 3 The particle size of the prepared powder secondary particles is normally distributed with a narrow distribution range, indicating that the copper powder prepared by the present invention has good consistency; the BET test found that the specific surface area is 36.6m 2 / g, can be used as an ideal carrier for catalysts.

[0024] Example 2 (1) 18.2 g of copper acetate was dissolved in 200 mL of deionized water to prepare a copper acetate solution. 1.2 g of a polyethylene glycol / sodium citrate composite structure control agent (polyethylene glycol and sodium citrate in a mass ratio of 1:2) was added. During the preparation process, nitrogen was introduced to remove oxygen from the solution. Oxalic acid was added to adjust the pH to 3.0. Argon was introduced for 20 min to remove oxygen from the solution. (2) The copper salt solution was transferred to a closed reactor protected by argon to maintain an oxygen-free environment. The solution was microwave-treated and heated to 90°C at a microwave power of 900 W / L solution. After maintaining for 10 minutes, it was transferred to an ultrasonic atomization device for ultrasonic atomization. Argon was used as the carrier gas for atomization (atomization pressure of 0.2 MPa) and the ultrasonic frequency was 40 kHz. (3) The atomized droplets are transported to a 980°C high-temperature pyrolysis furnace for high-temperature pyrolysis. The high-temperature pyrolysis is carried out in a H2 / Ar mixed atmosphere with a hydrogen volume fraction of 20% for 2 seconds; (4) The powder after the pyrolysis reaction was captured using high-purity water containing a dispersant CTAB and a reducing agent hydrazine hydrate, wherein the mass concentration of CTAB was 5% and the concentration of hydrazine hydrate was 0.2 mol / L. The product was separated after capture and washed with deionized water and ethanol multiple times. The washed product was dried and encapsulated to obtain hollow hydrangea nano-copper powder.

[0025] Example 3 (1) Dissolve 22.3 g of copper bromide in 200 mL of deionized water to prepare a copper bromide solution, add 0.3 g of polyethylene glycol / sodium citrate composite structure control agent (mass ratio of polyethylene glycol to sodium citrate is 1:0.5), and during the preparation process, pass argon gas to remove oxygen from the solution. Add oxalic acid to adjust the pH to 3.8, and pass argon gas for 30 minutes to remove oxygen from the solution. (2) The copper salt solution was transferred to a closed reactor protected by argon to maintain an oxygen-free environment. The solution was subjected to microwave treatment and heated to 80°C at a microwave power of 500 W / L solution. After maintaining for 30 minutes, it was transferred to an ultrasonic atomization device for ultrasonic atomization. Argon was used as the carrier gas for atomization (atomization pressure of 0.3 MPa) and the ultrasonic frequency was 20 kHz. (3) The atomized droplets are transported to a 400°C high-temperature pyrolysis furnace for high-temperature pyrolysis. The high-temperature pyrolysis is carried out in a H2 / Ar mixed atmosphere with a hydrogen volume fraction of 5% for 5 seconds; (4) The powder after the pyrolysis reaction was captured using high-purity water containing a dispersant SDS and a reducing agent hydrazine hydrate, wherein the mass concentration of SDS was 0.1% and the concentration of hydrazine hydrate was 0.05 mol / L. The product was separated after capture and washed with deionized water and ethanol multiple times. The washed product was dried and encapsulated to obtain hollow hydrangea nano-copper powder.

[0026] Example 4 (1) Dissolve 13.4 g of copper chloride and 12.4 g of copper sulfate in 200 mL of deionized water to prepare a mixed copper salt solution, add 1.5 g of polyethylene glycol / sodium citrate composite structure control agent (mass ratio of polyethylene glycol to sodium citrate is 1:3), add carbonic acid to adjust the pH to 6.5, and add hydrazine hydrate with a final concentration of 10 g / L as a deoxidizer; (2) The copper salt solution was transferred to a closed reactor protected by argon to maintain an oxygen-free environment. The solution was microwave-treated and heated to 88°C at a microwave power of 1000 W / L solution. After maintaining for 1 minute, it was transferred to an ultrasonic atomization device for ultrasonic atomization. Argon was used as the carrier gas for atomization (atomization pressure of 0.5 MPa) and the ultrasonic frequency was 40 kHz. (3) The atomized droplets are transported to a 750°C high-temperature pyrolysis furnace for high-temperature pyrolysis. The high-temperature pyrolysis is carried out in a H2 / Ar mixed atmosphere with a hydrogen volume fraction of 15% for 2 seconds; (4) The powder after the pyrolysis reaction was captured using high-purity water containing a dispersant PVP and a reducing agent hydrazine hydrate, wherein the mass concentration of PVP was 2% and the concentration of hydrazine hydrate was 0.05 mol / L. The product was separated after capture and washed with deionized water and ethanol multiple times. The washed product was dried and encapsulated to obtain hollow hydrangea nano-copper powder.

[0027] Example 5 (1) 18.6 g of copper perchlorate was dissolved in 200 mL of deionized water to prepare a copper perchlorate solution. 0.8 g of a polyethylene glycol / sodium citrate composite structure control agent (polyethylene glycol and sodium citrate in a mass ratio of 1:1) was added. During the preparation process, nitrogen was introduced to remove oxygen from the solution. Oxalic acid was added to adjust the pH to 5. Nitrogen was introduced for 30 minutes to remove oxygen from the solution. (2) The copper salt solution was transferred to a closed reactor protected by argon to maintain an oxygen-free environment. The solution was microwave-treated and heated to 85°C at a microwave power of 700 W / L solution. After maintaining for 25 minutes, it was transferred to an ultrasonic atomization device for ultrasonic atomization. Argon was used as the carrier gas for atomization (atomization pressure of 0.2 MPa) and the ultrasonic frequency was 30 kHz. (3) The atomized droplets were transported to a 580°C high-temperature pyrolysis furnace for high-temperature pyrolysis. The high-temperature pyrolysis was carried out in a H2 / Ar mixed atmosphere with a hydrogen volume fraction of 8% for 300 seconds. (4) The powder after the pyrolysis reaction was captured using high-purity water containing a dispersant CTAB and a reducing agent hydrazine hydrate, wherein the mass concentration of CTAB was 1% and the concentration of hydrazine hydrate was 0.05 mol / L. The product was separated after capture and washed with deionized water and ethanol multiple times. The washed product was dried and encapsulated to obtain hollow hydrangea nano-copper powder.

[0028] Example 6 (1) Dissolve 15.6 g of copper formate in 200 mL of deionized water to prepare a copper formate solution, add 2.0 g of a polyethylene glycol / sodium citrate composite structure control agent (the mass ratio of polyethylene glycol to sodium citrate is 1:1.5), add acetic acid to adjust the pH to 4.5, and add ascorbic acid as a deoxidizer at a final concentration of 8 g / L. (2) The copper salt solution was transferred to a closed reactor protected by argon to maintain an oxygen-free environment. The solution was microwave-treated and heated to 82°C at a microwave power of 600 W / L solution. After maintaining for 20 minutes, it was transferred to an ultrasonic atomization device for ultrasonic atomization. Argon was used as the carrier gas for atomization (atomization pressure of 0.3 MPa) and the ultrasonic frequency was 25 kHz. (3) The atomized droplets are transported to a 900°C high-temperature pyrolysis furnace for high-temperature pyrolysis. The high-temperature pyrolysis is carried out in a H2 / Ar mixed atmosphere with a hydrogen volume fraction of 18% for 1 second. (4) The powder after the pyrolysis reaction was captured using high-purity water containing a dispersant SDS and a reducing agent hydrazine hydrate, wherein the mass concentration of SDS was 3% and the concentration of hydrazine hydrate was 0.15 mol / L. The product was separated after capture and washed with deionized water and ethanol multiple times. The washed product was dried and encapsulated to obtain hollow hydrangea nano-copper powder.

[0029] The specific embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope 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 a copper salt solution, and add a structure control agent. During the preparation process, introduce argon gas to remove oxygen from the solution, adjust the pH value of the copper salt solution to 3.0-6.5, and then degas the solution; (2) The copper salt solution is transferred to a closed reactor, maintained in an oxygen-free environment, and the solution is subjected to microwave treatment and then ultrasonic atomization; (3) subjecting the ultrasonically atomized droplets to high-temperature pyrolysis; (4) After the pyrolysis is completed, high-purity water containing a dispersant and a reducing agent is used for capture. The product is separated after capture and washed multiple times with deionized water and ethanol. The washed product is dried and encapsulated to obtain hollow hydrangea nano-copper powder.

2. The method for preparing highly uniform ultra-dispersed nano hollow hydrangea copper powder according to claim 1, characterized in that: The soluble copper salts in step (1) 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: In step (1), the structure control agent is a mixture of polyethylene glycol and sodium citrate, and the mass ratio of polyethylene glycol to sodium citrate is 1:0.5-1:3; the mass of the soluble copper salt is more than 7 times that of the structure control agent.

4. The method for preparing highly uniform ultra-dispersed nano hollow hydrangea copper powder according to claim 1, characterized in that: In step (2), the oxygen-free environment is maintained by continuously introducing an inert gas or placing a deoxidizer, wherein the inert gas includes nitrogen or argon; the deoxidizer includes ascorbic acid, hydrazine hydrate, and BHJ, and the amount of the deoxidizer added is 8-10 g / L copper salt solution.

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

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

7. 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 mixed gas of hydrogen and inert gas as the protective atmosphere, wherein the volume fraction of hydrogen is 5-20%, and the inert gas includes nitrogen and argon. The pyrolysis temperature is 400-980°C and the pyrolysis time is 1-300 seconds.

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

9. 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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