A nanometer copper particle in the shape of a dewberry and a preparation method and application thereof

Abstract

The application discloses a raspberry-shaped nano copper particle and a preparation method and application thereof, and relates to the technical field of nano materials, and in particular relates to a raspberry-shaped nano copper particle and a preparation method and application thereof. The copper precursor is fully dissolved by using an organic solvent to form a copper ion solution, the copper ion is attached to large-sized copper particles to grow into small-sized particles by using a hot injection method, and finally, the nano particles with a shape similar to raspberry fruits are grown. The powder is uniformly sprayed on a glass slide, and is placed in a reducing atmosphere to be annealed to form a dense conductive film. Under the premise of low cost and easy operation, the small particles attached to the structure surface fill the gaps between the large particles in the annealing process, the particles are crosslinked to be more compact, the sintering temperature and the resistivity of the film are successfully reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of nanometer metal synthesis and conductive application, and relates to a nanometer copper particle in the shape of a snakeberry as well as a preparation method and application thereof. BACKGROUND

[0002] Nanometer copper is a very important metal material, which has excellent conductivity, thermal conductivity and ductility, and can be applied in the fields of machinery, chemical industry, electronics and the like. At present, the method for synthesizing nanometer copper mainly includes liquid phase method, such as solvothermal method, hydrothermal method, microwave-assisted method and polyol method and the like. The morphology of nanometer copper has an important influence on its performance and application, for example, copper nanowire can be prepared into a transparent electrode; copper nanosheet can be used as a catalyst for CO electro-reduction; and copper nanocube can be used to study the self-assembly process of nanometer particles.

[0003] For conductive materials, silver is favored due to its high conductivity and chemical stability. However, its high cost limits its application in printed electronic products. Indium tin oxide (ITO) has high transmittance and conductivity and is often used as a transparent conductor, but it is scarce, fragile, expensive and has a complex preparation process. In contrast, copper has high resistance to ion migration, and its price is low and its conductivity is high, and it is considered as a good conductive material that can replace silver and ITO. The main problem related to copper particles is their low oxidation resistance under ambient air conditions. Therefore, in the process of synthesizing copper nanoparticles, a strong organic stabilizer is generally used, which can effectively prevent the oxidation and aggregation of copper nanoparticles, and the annealing process in a reducing atmosphere can promote the particles to connect together to form a cross-linked network, realizing the conductive application. When using relatively large size copper particles to prepare a conductive film, large cracks and gaps are easily formed in the annealing process, and it is difficult to synthesize small size monodisperse nanoparticles. SUMMARY

[0004] The present application aims to solve the technical problems of the prior art, and provides a nanometer copper structure in the shape of a snakeberry, which can effectively fill the gaps and cracks between particles in the annealing process, so that the film becomes more dense, the conductivity of the film is improved, and the annealing temperature is reduced.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0006] A preparation method of a nanometer copper particle in the shape of a snakeberry, comprising the following steps:

[0007] (1) mixing a copper precursor and an organic solvent I to form a mixed solution, then heating to 110-220℃ and keeping for 3-120min to form a Cu 2+ solution, and then cooling to room temperature;

[0008] (2) mixing copper oxide with organic solvent I, then heating to 220-320℃ and keeping for 30-120 min;

[0009] (3) adding Cu2+ solution obtained in step (1) into the reaction solution in step (2), continuing to keep for 5-60 min, then cooling to room temperature, centrifugal separation, and drying to obtain. 2+

[0010] Specifically, in step (1), the copper precursor is any one or a combination of two or more of basic copper carbonate, basic copper acetate, basic copper nitrate, copper formate, copper hydroxide, copper oleate, and copper oxalate; the organic solvent I is any one or a mixture of two or more of oleylamine, octadecylamine, oleic acid, alkanoic acid, enamine, enoic acid, alkynylamine, and alkyne acid and their isomers; the mass fraction of the copper precursor in the mixed solution is 5-38%.

[0011] Specifically, in step (2), the copper oxide is nano or micro copper oxide powder; the organic solvent I is the same as in step (1); the copper oxide and the organic solvent are mixed at 0.2-0.5 mmol / L.

[0012] Preferably, in step (3), the Cu2+ solution is injected into the reaction solution in step (2) at a rate of 0.05-0.1 ml / min; the molar ratio of the Cu2+ solution in step (1) to the copper element in the reaction solution in step (2) is (1.14-13.47):1. 2+ 2+ Preferably, in step (3), the Cu2+ solution is injected into the reaction solution in step (2) at a rate of 0.05-0.1 ml / min; the molar ratio of the Cu2+ solution in step (1) to the copper element in the reaction solution in step (2) is (1.14-13.47):1.

[0013] Further, the application also claims the snakeberry-shaped nanometer copper particles prepared by the above preparation method.

[0014] Further, the snakeberry-shaped nanometer copper particles prepared by the application are formed by growing small-size copper particles on large-size copper particles, and the average diameter of the whole particle is 20-70 nm, and the average diameter of the small-size copper particle is 2-10 nm.

[0015] Further, the application also claims the application of the snakeberry-shaped nanometer copper particles in the preparation of copper conductive thin films.

[0016] Further, the application also claims a copper conductive thin film prepared by the following steps:

[0017] S1: dispersing the nanometer copper particles prepared in claim 1 in organic solvent II to form a suspension and ultrasonic dispersion;

[0018] ​​S2: the suspension of step S1 is sprayed onto the substrate to form a copper film, and the thickness of the film is controlled by the number of spraying times;

[0019] S3: the copper film formed in step S2 is annealed in a protective atmosphere.

[0020] Preferably, in step S1, the organic solvent II is selected from any one or a mixture of two or more of toluene, benzene, n-hexane and n-heptane; the mass fraction of the copper nanoparticles in the suspension is 10-80%; and the ultrasonic dispersion time is 20-30 min.

[0021] Preferably, in step S2, the suspension is loaded into an electric spray pen or a gas pump spray pen with a caliber of 0.2-1 mm, the working frequency of the spray pen is controlled to be 50-60 Hz or the gas flow of the gas pump spray pen is controlled to be 0.1-1 L / min, and the suspension is uniformly sprayed onto a glass sheet or a silicon sheet; and the thickness of the finally formed film is controlled to be 2-20 μm.

[0022] Preferably, in step S3, the annealing temperature is 200-800℃, the heating rate is 10℃ / min, the annealing time is 30-120 min; and the annealing atmosphere is a mixture of hydrogen and argon with a ratio of 1:(9-19).

[0023] Advantages:

[0024] The present application adopts a low-cost and simple method to synthesize nanoparticles, and in the process of annealing into a film, compared with regular spherical nanoparticles, the small particles attached to the surface of the raspberry-shaped nanoparticles fill the gaps between the large particles and act as a bridge to connect the large particles, which helps to form a more dense cross-linked conductive network and realize the process of preparing a high-conductive film at a low temperature. BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and / or other aspects of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the accompanying drawings, in which:

[0026] Figure 1 is a flowchart of the hot injection reaction.

[0027] Figure 2 is a TEM image of the copper powder in Example 1.

[0028] Figure 3 is an XRD of the copper powder in Example 1.

[0029] Figure 4 is an SEM image of the film after annealing in Example 1. DETAILED DESCRIPTION

[0030] The application can be better understood in accordance with the following examples.

[0031] Example 1

[0032] Combination Figure 1 Preparation of raspberry-shaped copper nanoparticles and copper conductive thin film:

[0033] (1) 10 mmol of basic copper carbonate and 30 ml of oleylamine were mixed, the mass fraction of the mixture was 8%, and heated to 200°C. After keeping at this temperature for 1 hour, it was cooled to room temperature to obtain a copper ion-oleylamine complex solution.

[0034] (2) 10 mmol of copper oxide and 30 ml of oleylamine were mixed, and heated to 250°C. After keeping at this temperature for 1 hour, the copper ion-oleylamine complex solution obtained in step (1) was injected into the solution in step (2) at an injection rate of 0.05 ml / min, the molar ratio of copper elements in the solutions of step (1) and step (2) was 2:1, and after keeping for 30 minutes, it was cooled to room temperature.

[0035] (3) The reacted solution was centrifuged using a mixed solution of n-hexane and ethanol at a ratio of 3:1, and centrifuged at a speed of 8000 r / min for 5 minutes. This operation was repeated until the upper liquid was clear and transparent. Figure 2 The TEM picture of the product can clearly see the large particles in the center and the small particles in the outer layer, and the diameter of the small particles is about 7.66 nm. Figure 3 The XRD of the product is shown, and the composition of the substance is face-centered cubic Cu.

[0036] (4) The obtained copper powder was dispersed into toluene to form a suspension with a concentration of 20%, and subjected to ultrasonic treatment for 30 minutes. The suspension after ultrasonic treatment was uniformly sprayed on a glass slide using an electric spray pen, and the toluene volatilized after heating, and the copper powder accumulated into a thin film.

[0037] (5) The thin film was placed in a tube furnace for annealing, the temperature was set to 250°C, the heating rate was 10°C / min, and the annealing time was 1 hour, and at the same time, the furnace was always filled with 10% H2 and 90% Ar. Figure 4 The SEM picture of the thin film after annealing is shown, from which it can be observed that the particles are crosslinked together to form a conductive structure, and the small size particles play a filling role, and the resistivity is 90.03 μΩ·cm.

[0038] Example 2

[0039] (1) 10 mmol of basic copper carbonate and 30 ml of oleic acid were mixed to form a mixture with a mass fraction of 7.68%, which was heated to 150°C and kept at this temperature for 1 hour, and then cooled to room temperature to obtain a copper ion-oleic acid complex.

[0040] (2) 10 mmol of copper oxide and 30 ml of oleic acid were mixed and heated to 250°C, and then a solution of the copper ion-oleic acid complex obtained in step (1) was injected into the solution in step (2) at an injection rate of 0.05 ml / min, the molar ratio of copper in the solution in step (1) to that in step (2) being 2:1, and the solution was kept at this temperature for 30 minutes and then cooled to room temperature.

[0041] (3) The reacted solution was centrifuged using a mixed solution of n-hexane and ethanol at a ratio of 3:1 at a rotation speed of 8000 r / min for 5 minutes, and the operation was repeated until the supernatant was clear and transparent.

[0042] (4) The obtained copper powder was dispersed in toluene to form a suspension with a concentration of 20%, and then subjected to ultrasonic treatment for 30 minutes. The suspension after ultrasonic treatment was uniformly sprayed on a glass slide using an electric spray pen, and the toluene was volatilized after heating, and the copper powder accumulated to form a dense thin film.

[0043] (5) The thin film was annealed in a tube furnace, the temperature was set to 250°C, the heating rate was 10°C / min, and the annealing time was 1 hour, and at the same time, the furnace was always filled with 10% H2 and 90% Ar. The resistivity of the thin film was 46.34 μΩ·cm.

[0044] Example 3

[0045] (1) 15 mmol of anhydrous copper acetate and 30 ml of oleic acid were mixed to form a mixture with a mass fraction of 10.05%, which was heated to 150°C and kept at this temperature for 1 hour, and then cooled to room temperature to obtain a copper ion-oleic acid complex.

[0046] (2) 10 mmol of copper oxide and 30 ml of oleic acid were mixed and heated to 250°C, and then a solution of the copper ion-oleic acid complex obtained in step (1) was injected into the solution in step (2) at an injection rate of 0.05 ml / min, the molar ratio of copper in the solution in step (1) to that in step (2) being 1.5:1, and the solution was kept at this temperature for 30 minutes and then cooled to room temperature.

[0047] (3) The reacted solution was centrifuged using a mixed solution of n-hexane and ethanol at a ratio of 3:1 at a rotation speed of 8000 r / min for 5 minutes, and the operation was repeated until the supernatant was clear and transparent.

[0048] (4) The obtained copper powder was dispersed in toluene to form a suspension with a concentration of 20%, and was subjected to ultrasonic treatment for 30 minutes. The suspension after ultrasonic treatment was uniformly sprayed on a glass slide using an electric spray pen, and the toluene was volatilized after being heated, and the copper powder accumulated into a dense thin film.

[0049] (5) The thin film was annealed in a tube furnace, the temperature was set to 250°C, the heating rate was 10°C / min, and the time was 1 hour, and at the same time, the furnace was always filled with 10% H2and 90% Ar. The resistivity of the thin film was 100.18 μΩ·cm.

[0050] Comparative Example 1

[0051] (1) 10 mmol of copper oxide and 30 ml of oleylamine were mixed, heated to 250°C, and kept at this temperature for 1 hour, and then cooled to room temperature.

[0052] (2) The reaction solution was centrifuged using a mixed solution of n-hexane and ethanol at a ratio of 3:1, and centrifuged at a speed of 8000 r / min for 5 minutes, and the operation was repeated until the supernatant was clear and transparent.

[0053] (3) The obtained copper powder was dispersed in toluene to form a suspension with a concentration of 20%, and was subjected to ultrasonic treatment for 30 minutes. The suspension after ultrasonic treatment was uniformly sprayed on a glass slide using an electric spray pen, and the toluene was volatilized after being heated, and the copper powder accumulated into a dense thin film.

[0054] (4) The thin film was annealed in a tube furnace, the temperature was set to 250°C, the heating rate was 10°C / min, and the time was 1 hour, and at the same time, the furnace was always filled with 10% H2and 90% Ar. The final obtained thin film was not conductive, and its resistivity was too high, and the obtained product was all directly converted from large particles, without small particles connecting them together, and it was impossible to synthesize nanometer particles with raspberry structure.

[0055] Comparative Example 2

[0056] (1) 0.1 mol of basic copper carbonate and 30 ml of oleylamine were mixed in a four-necked flask, and the mass fraction of the mixed solution was 43%, and heated to 200°C, and kept at this temperature for 1 hour, and then cooled to room temperature.

[0057] (2) 10 mmol of copper oxide and 30 ml of oleylamine were mixed, heated to 250°C, and kept at this temperature for 1 hour, and then cooled to room temperature.

[0058] (3) After the reaction, the solution is centrifuged using a mixture of n-hexane and ethanol 3:1, at a speed of 8000 r / min for 5 minutes, and the operation is repeated until the supernatant is clear.

[0059] (4) The obtained copper powder is dispersed in toluene to form a suspension with a concentration of 20%, and the suspension is ultrasonically treated for 30 minutes. The ultrasonically treated suspension is uniformly sprayed on a glass slide using an electric spray pen, and the toluene is volatilized after heating, and the copper powder is accumulated into a thin film.

[0060] The thin film is annealed in a tube furnace, the temperature is set to 250℃, the heating rate is 10℃ / min, and the time is 1 hour, and at the same time, the furnace is always filled with 10% H2 and 90% Ar. The final film is in a broken state, because in step (1), the mass fraction of the mixed solution is too large, resulting in a large amount of precursor that cannot be dissolved to form copper ions, and only a small part will form small particles at 250℃, and a large amount of undissolved basic copper carbonate will directly decompose, resulting in uneven size particles, and the raspberry-shaped nanoparticles cannot be synthesized, and a dense conductive network cannot be formed during the annealing process.

[0061] The present application provides a raspberry-shaped copper nanoparticle and its preparation method and application ideas and methods, there are many methods and ways to realize the technical scheme, the above-mentioned is only the preferred embodiment of the present application, it should be pointed out that, for ordinary skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should be considered as the protection scope of the present application. The components not explicitly described in the embodiment can be realized by the existing technology.

Claims

1. A method for preparing nanometer copper particles in the shape of a dewberry, characterized in that, It comprises the following steps: (1) mixing a copper precursor and an organic solvent I to form a mixed solution, then heating to 110-220 °C and keeping for 3-120 min to form Cu 2+ solution, then cooling to room temperature; (2) mixing copper oxide with organic solvent I, and then heating to 220-320 ℃ and keeping for 30-120 min; (3) Cu powder obtained in step (1) is added into the solution obtained in step (2) and kept at 60-80°C for 5-60 min, then cooled to room temperature, centrifuged and dried to obtain Cu powder. 2+ solution obtained in step (2) and kept at 60-80°C for 5-60 min, then cooled to room temperature, centrifuged and dried to obtain Cu powder. In step (1), the copper precursor is any one or a combination of two or more of basic copper carbonate, basic copper acetate, basic copper nitrate, copper formate, copper hydroxide, copper oleate, and copper oxalate; the organic solvent I is any one or a mixture of two or more of oleylamine, octadecylamine, oleic acid, alkanoic acid, enamine, enoic acid, acetylene amine, acetylene acid, and their isomers; the mass fraction of the copper precursor in the mixed solution is 5-38%; In step (2), the copper oxide is selected from nano or micro copper oxide powder; the organic solvent I is the same as in step (1); the copper oxide and the organic solvent are mixed at a concentration of 0.2-0.5 mmol / L; In step (3), the Cu 2+ The solution is injected into the reaction solution of step (2) at an injection rate of 0.05-0.1 ml / min; the Cu 2+ The molar ratio of the solution of step (1) to the copper element in the reaction solution of step (2) is (1.14-13.47):

1.

2. The nanometer copper particles in the shape of a dewberry prepared by the preparation method of claim 1, characterized in that, It is a nanometer copper particle in the shape of a raspberry, formed by small-size copper particles growing on large-size copper particles, with the average diameter of the whole particle being 20-70 nm and the average diameter of the small-size copper particles being 2-10 nm.

3. The raspberry-shaped nanometer copper particle of claim 2 for use in the preparation of a copper conductive thin film.

4. A copper conductive film, characterized by, It is prepared by the following steps: S1: dispersing the nanometer copper particle prepared in claim 1 in an organic solvent II to form a suspension and ultrasonic dispersion; S2: uniformly spraying the suspension of step S1 onto a substrate in the form of a copper thin film by spraying, and controlling the thickness of the thin film by the number of spraying times; S3: annealing the copper thin film formed in step S2 in a protective atmosphere, and the copper conductive thin film is obtained.

5. The copper conductive film according to claim 4, wherein In step S1, the organic solvent II is any one or a mixture of two or more of toluene, benzene, n-hexane, and n-heptane; the mass fraction of the nanometer copper particle in the suspension is 10-80%; and the ultrasonic dispersion time is 20-30 min.

6. The copper conductive film according to claim 4, wherein In step S2, the suspension is loaded into an electric spray pen or a gas pump spray pen with a caliber of 0.2-1 mm, the working frequency of the spray pen is controlled at 50-60 Hz, or the gas flow rate of the gas pump spray pen is controlled at 0.1-1 L / min, and the suspension is uniformly sprayed onto a glass sheet or a silicon wafer; and the final thickness of the thin film is controlled at 2-20 μm.

7. The copper conductive film according to claim 4, wherein In step S3, the annealing temperature is 200-800 ℃, the heating rate is 10 ℃ / min, the annealing time is 30-120 min; and the annealing atmosphere is a mixture of hydrogen and argon with a ratio of 1: (9-19).

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