A method for preparing carbon-coated nickel-copper alloy nanosheets and the corresponding materials

Abstract

This invention relates to the field of electromagnetic wave absorbing materials, specifically a method for preparing carbon-coated nickel-copper alloy nanosheets and the corresponding material. The method includes: adding a surfactant to a mixed solution of copper salt, nickel salt, and solvent under an argon atmosphere to obtain a nickel-copper alloy nanosheet solution; adding ethanol to the obtained nickel-copper alloy nanosheet solution for precipitation; centrifuging and washing the precipitate at high speed to dissolve it; ultrasonically dispersing and washing the dissolved solution; vacuum drying the product to obtain nickel-copper alloy nanosheet powder; mixing the powder with a carbon source; grinding the powder to obtain a mixed powder of nickel-copper alloy nanosheets and carbon source; and sintering the powder at high temperature under a protective atmosphere to obtain the carbon-coated nickel-copper alloy nanosheet material. The carbon-coated nickel-copper alloy nanosheet material prepared by this invention achieves excellent electromagnetic wave absorption performance at a relatively thin thickness, enabling the absorption of electromagnetic waves within a very small space.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing materials technology, and in particular to a method for preparing carbon-coated nickel-copper alloy nanosheets and the corresponding materials. Background Technology

[0002] With the rapid development of technology and the large-scale application of electronic devices, electromagnetic pollution has become increasingly serious, not only interfering with normal communication but also endangering human health. Absorbing materials can convert electromagnetic waves into heat energy and other forms of energy through methods such as absorption and scattering within the material, thus achieving the functions of dissipating, attenuating, and absorbing electromagnetic waves.

[0003] Among existing microwave absorbing materials, nickel and its alloys, as magnetic loss type microwave absorbers, are not conducive to electromagnetic wave absorption due to their high density, large magnetic loss, small dielectric loss, and impedance mismatch. When carbon nanotubes are used alone as microwave absorbers, they are dielectric loss type, which has a high dielectric constant, and a large number of electromagnetic waves cannot enter the interior of the material, resulting in poor microwave absorption performance.

[0004] Therefore, how to improve the insufficient magnetic loss performance of carbon nanotubes as absorbers and the insufficient electrical loss performance of metal materials as absorbers alone, and provide a material preparation method that integrates magnetic and electrical dielectric structures to enhance electromagnetic wave absorption, has become an urgent technical problem to be solved. Summary of the Invention

[0005] In view of this, in order to overcome the shortcomings of the prior art, the present invention provides a method for preparing carbon-coated nickel-copper alloy nanosheets and the corresponding materials. By fully utilizing the synergistic effect of multi-component losses, the impedance matching of the composite material is improved, thereby enhancing the microwave absorption performance and achieving lightweight, high-strength, and broadband electromagnetic wave absorption effects. Furthermore, a high-performance microwave absorbing material is prepared based on the prepared filler.

[0006] On one hand, the present invention provides a method for preparing carbon-coated nickel-copper alloy nanosheets, comprising:

[0007] Step 1: Preparation of the nickel-copper alloy nanosheet reaction solution

[0008] Copper salt, nickel salt, solvent and surfactant were prepared by molar ratio (1-3):10:100:(8-10). Under an argon atmosphere with a gas flow rate of 25 sccm, the mixed solution of copper salt, nickel salt and solvent was stirred at 110℃ for 20 min, and then the surfactant was added. After stirring for another 5 min, the temperature was raised to 180-240℃ and held for 1 h to obtain nickel-copper alloy nanosheet solution.

[0009] Step 2: Preparation of nickel-copper alloy nanosheet powder

[0010] Ethanol with a volume ratio of 1:2 to the nickel-copper alloy nanosheet solution obtained in step one was added to precipitate the nanosheets. The precipitate was washed by high-speed centrifugation. The precipitate was dissolved in sufficient n-hexane to obtain a solution. The solution was ultrasonically dispersed and washed repeatedly with sufficient ethanol. The product was then vacuum dried to obtain nickel-copper alloy nanosheet powder.

[0011] Step 3: Preparation of a mixed powder of nickel-copper alloy nanosheets and carbon source

[0012] The nickel-copper alloy nanosheet powder prepared in step two was mixed with carbon sources in different mass ratios and then ground thoroughly to obtain a mixed powder of nickel-copper alloy nanosheets and carbon sources.

[0013] Step 4: Preparation of carbon-coated nickel-copper alloy nanosheets. The nickel-copper alloy nanosheets obtained in Step 3 are mixed with carbon source powder and subjected to high-temperature sintering in a protective atmosphere to obtain carbon-coated nickel-copper alloy nanosheets.

[0014] As a preferred embodiment of the present invention, in step one of the preparation method of carbon-coated nickel-copper alloy nanosheets of the present invention, the copper salt is copper chloride dihydrate or copper acetylacetonate, the nickel salt is one of nickel acetylacetonate, nickel stearate or nickel acetate, the solvent is one of oleylamine, octadeceneamine or N'N-dimethylformamide, and the surfactant is one of tri-n-octylphosphine, triphenylphosphine or trioctylphosphine oxide.

[0015] As a preferred embodiment of the present invention, in step two of the method for preparing carbon-coated nickel-copper alloy nanosheets, the centrifugal speed for high-speed centrifugal washing is 8000 rpm and the high-speed centrifugal washing time is 3 min.

[0016] As a preferred embodiment of the present invention, in step two of the preparation method of carbon-coated nickel-copper alloy nanosheets of the present invention, the vacuum drying temperature is 60°C and the vacuum drying time is 12h.

[0017] As a preferred embodiment of the present invention, in step three of the method for preparing carbon-coated nickel-copper alloy nanosheets, the carbon source is one of melamine, glucose, or dopamine.

[0018] As a preferred embodiment of the present invention, in step three of the preparation method of carbon-coated nickel-copper alloy nanosheet material of the present invention, the mass ratio of nickel-copper alloy nanosheet powder to carbon source is 1:1 to 1:20.

[0019] As a preferred embodiment of the present invention, in step four of the method for preparing carbon-coated nickel-copper alloy nanosheets, the protective atmosphere is a nitrogen atmosphere with a gas flow rate of 50-100 sccm.

[0020] As a preferred embodiment of the present invention, in step four of the preparation method of carbon-coated nickel-copper alloy nanosheet material of the present invention, the high-temperature sintering treatment includes: heating to 700-900℃ at a heating rate of 5-10℃ / min and holding for 1-3 hours, cooling to 300℃ at a rate of 10℃ / min and then naturally cooling.

[0021] On the other hand, the present invention provides a carbon-coated nickel-copper alloy nanosheet material, which is prepared according to the above-mentioned preparation method of carbon-coated nickel-copper alloy nanosheet material.

[0022] As a preferred embodiment of the present invention, in the carbon-coated nickel-copper alloy nanosheet material of the present invention, carbon coats the nickel-copper alloy nanosheets in the form of carbon nanotubes or spherical carbon shell structures.

[0023] The preparation method and corresponding materials of carbon-coated nickel-copper alloy nanosheets of the present invention have the following beneficial effects:

[0024] 1. A method for preparing nickel-copper alloy nanosheets with controllable morphology and uniform size was used, and the nickel-copper atomic ratio of the nickel-copper alloy nanosheets could be controlled by adjusting the molar ratio of nickel salt and copper salt.

[0025] 2. Graphite carbon is formed by high-temperature sintering of carbon source, which enhances the conductivity of the material. The bonding form between nickel-copper nanosheets and carbon coating layer can be flexibly adjusted by changing the proportion of carbon source. The carbon coating layer includes carbon nanotubes and spherical carbon shell structures, which is beneficial for controlling its electromagnetic wave absorption characteristics.

[0026] 3. The carbon-coated nickel-copper alloy nanosheet material prepared by this invention achieves effective combination of magnetic and electrical media through the coating structure, realizing excellent electromagnetic wave absorption performance at a relatively thin thickness, enabling the absorption of electromagnetic waves in a very small space and solving the problem of strong electromagnetic wave radiation.

[0027] 4. The preparation method of the present invention is simple to operate, safe in process, and uses conventional equipment, which is conducive to industrialization. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 The X-ray diffraction patterns are those of the nickel-copper alloy nanosheets prepared in Examples 1, 2 and 3 of this invention.

[0030] Figure 2 The X-ray diffraction patterns are those of the carbon-coated nickel-copper alloy nanosheets prepared in Examples 4, 5, and 6 of this invention.

[0031] Figure 3 This is a transmission electron microscope image of the nickel-copper alloy nanosheets prepared in Example 2 of the present invention;

[0032] Figure 4 This is a transmission electron microscope image of the carbon-coated nickel-copper alloy nanosheet material prepared in Example 4 of the present invention;

[0033] Figure 5 This is a transmission electron microscope image of the carbon-coated nickel-copper alloy nanosheet material prepared in Example 5 of the present invention;

[0034] Figure 6 This is a transmission electron microscope image of the carbon-coated nickel-copper alloy nanosheet material prepared in Example 6 of the present invention;

[0035] Figure 7 This is a reflection loss diagram of the carbon-coated nickel-copper alloy nanosheet material sample prepared in Example 4 of the present invention. Detailed Implementation

[0036] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0037] It should be noted that, in the absence of conflict, the following embodiments and features can be combined with each other; and, based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0038] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0039] Example 1

[0040] Step 1: Preparation of the nickel-copper alloy nanosheet reaction solution

[0041] The materials were prepared by mixing 1 mmol of copper chloride dihydrate, 10 mmol of nickel acetate, 100 mmol of oleylamine and 8 mmol of surfactant tri-n-octylphosphine. Under an argon atmosphere with a gas flow rate of 25 sccm, the mixed solution of copper salt, nickel salt and solvent was stirred at 110 °C for 20 min, and then the surfactant was added. After stirring for another 5 min, the temperature was raised to 180 °C and held for 1 h to obtain a nickel-copper alloy nanosheet solution.

[0042] Step 2: Preparation of nickel-copper alloy nanosheet powder

[0043] Add 150 mL of ethanol to 75 mL of the nickel-copper alloy nanosheet solution obtained in step one to precipitate. Wash the precipitate by high-speed centrifugation at 8000 rpm for 3 min. Dissolve the precipitate in sufficient n-hexane to obtain a solution. Disperse the solution by ultrasonication and wash repeatedly with sufficient ethanol. Vacuum dry the product at 60℃ for 12 h to obtain nickel-copper alloy nanosheet powder.

[0044] Step 3: Preparation of a mixed powder of nickel-copper alloy nanosheets and carbon source

[0045] Mix 0.1g of the nickel-copper alloy nanosheet powder prepared in step two with 2g of glucose, and grind thoroughly to obtain a mixed powder of nickel-copper alloy nanosheets and glucose.

[0046] Step 4: Preparation of carbon-coated nickel-copper alloy nanosheets. The mixed powder of nickel-copper alloy nanosheets obtained in step 3 and glucose was subjected to high-temperature sintering treatment in a protective atmosphere. The protective atmosphere was a nitrogen atmosphere with a gas flow rate of 50 sccm. The temperature was raised to 800℃ at a heating rate of 10℃ / min and held for 3 hours. After cooling to 300℃ at a heating rate of 10℃ / min, the material was naturally cooled to obtain carbon-coated nickel-copper alloy nanosheets.

[0047] Example 2

[0048] Step 1: Preparation of the nickel-copper alloy nanosheet reaction solution

[0049] The materials were prepared by mixing 2 mmol of copper chloride dihydrate, 10 mmol of nickel acetylacetonate, 100 mmol of octadeceneamine and 9 mmol of the surfactant tri-n-octylphosphine. Under an argon atmosphere with a gas flow rate of 25 sccm, the mixed solution of copper salt, nickel salt and solvent was stirred at 110 °C for 20 min, and then the surfactant was added. After stirring for another 5 min, the temperature was raised to 200 °C and held for 1 h to obtain a nickel-copper alloy nanosheet solution.

[0050] Step 2: Preparation of nickel-copper alloy nanosheet powder

[0051] Add 150 mL of ethanol to 75 mL of the nickel-copper alloy nanosheet solution obtained in step one to precipitate. Wash the precipitate by high-speed centrifugation at 8000 rpm for 3 min. Dissolve the precipitate in sufficient n-hexane to obtain a solution. Disperse the solution by ultrasonication and wash repeatedly with sufficient ethanol. Vacuum dry the product at 60℃ for 12 h to obtain nickel-copper alloy nanosheet powder.

[0052] Step 3: Preparation of a mixed powder of nickel-copper alloy nanosheets and carbon source

[0053] Mix 0.1g of the nickel-copper alloy nanosheet powder prepared in step two with 0.5g of dopamine, and grind thoroughly to obtain a mixed powder of nickel-copper alloy nanosheets and dopamine.

[0054] Step 4: Preparation of carbon-coated nickel-copper alloy nanosheets. The nickel-copper alloy nanosheets obtained in Step 3 and the dopamine mixed powder were subjected to high-temperature sintering treatment in a protective atmosphere. The protective atmosphere was a nitrogen atmosphere with a gas flow rate of 70 sccm. The temperature was raised to 700℃ at a heating rate of 7℃ / min and held for 2 hours. The temperature was then lowered to 300℃ at a rate of 10℃ / min and allowed to cool naturally to obtain carbon-coated nickel-copper alloy nanosheets.

[0055] Example 3

[0056] Step 1: Preparation of the nickel-copper alloy nanosheet reaction solution

[0057] The materials were prepared by mixing 3 mmol of copper acetylacetonate, 10 mmol of nickel stearate, 100 mmol of N'N-dimethylformamide and 10 mmol of surfactant triphenylphosphine. Under an argon atmosphere with a gas flow rate of 25 sccm, the mixed solution of copper salt, nickel salt and solvent was stirred at 110 °C for 20 min, and then the surfactant was added. After stirring for another 5 min, the temperature was raised to 220 °C and held for 1 h to obtain a nickel-copper alloy nanosheet solution.

[0058] Step 2: Preparation of nickel-copper alloy nanosheet powder

[0059] Add 150 mL of ethanol to 75 mL of the nickel-copper alloy nanosheet solution obtained in step one to precipitate. Wash the precipitate by high-speed centrifugation at 8000 rpm for 3 min. Dissolve the precipitate in sufficient n-hexane to obtain a solution. Disperse the solution by ultrasonication and wash repeatedly with sufficient ethanol. Vacuum dry the product at 60℃ for 12 h to obtain nickel-copper alloy nanosheet powder.

[0060] Step 3: Preparation of a mixed powder of nickel-copper alloy nanosheets and carbon source

[0061] Mix 0.1g of the nickel-copper alloy nanosheet powder prepared in step two with 0.7g of dopamine, and grind thoroughly to obtain a mixed powder of nickel-copper alloy nanosheets and dopamine.

[0062] Step 4: Preparation of carbon-coated nickel-copper alloy nanosheets. The nickel-copper alloy nanosheets obtained in Step 3 and the dopamine mixed powder were subjected to high-temperature sintering treatment in a protective atmosphere. The protective atmosphere was a nitrogen atmosphere with a gas flow rate of 80 sccm. The temperature was raised to 700℃ at a heating rate of 10℃ / min and held for 2 hours. After cooling to 300℃ at a heating rate of 10℃ / min, the material was naturally cooled to obtain carbon-coated nickel-copper alloy nanosheets.

[0063] Example 4

[0064] Step 1: Preparation of the nickel-copper alloy nanosheet reaction solution

[0065] The materials were prepared by mixing 2 mmol of copper chloride dihydrate, 10 mmol of nickel acetylacetonate, 100 mmol of octadeceneamine and 9 mmol of the surfactant triphenylphosphine. Under an argon atmosphere with a gas flow rate of 25 sccm, the mixed solution of copper salt, nickel salt and solvent was stirred at 110 °C for 20 min, and then the surfactant was added. After stirring for another 5 min, the temperature was raised to 220 °C and held for 1 h to obtain a nickel-copper alloy nanosheet solution.

[0066] Step 2: Preparation of nickel-copper alloy nanosheet powder

[0067] Add 150 mL of ethanol to 75 mL of the nickel-copper alloy nanosheet solution obtained in step one to precipitate. Wash the precipitate by high-speed centrifugation at 8000 rpm for 3 min. Dissolve the precipitate in sufficient n-hexane to obtain a solution. Disperse the solution by ultrasonication and wash repeatedly with sufficient ethanol. Vacuum dry the product at 60℃ for 12 h to obtain nickel-copper alloy nanosheet powder.

[0068] Step 3: Preparation of a mixed powder of nickel-copper alloy nanosheets and carbon source

[0069] Mix 0.1g of the nickel-copper alloy nanosheet powder prepared in step two with 1.5g of melamine, and grind thoroughly to obtain a mixed powder of nickel-copper alloy nanosheets and melamine.

[0070] Step 4: Preparation of carbon-coated nickel-copper alloy nanosheets. The mixed powder of nickel-copper alloy nanosheets obtained in step 3 and melamine was subjected to high-temperature sintering treatment in a protective atmosphere. The protective atmosphere was a nitrogen atmosphere with a gas flow rate of 100 sccm. The temperature was raised to 900℃ at a heating rate of 5℃ / min and held for 1 hour. After cooling to 300℃ at a rate of 10℃ / min, the material was naturally cooled to obtain carbon-coated nickel-copper alloy nanosheets.

[0071] Example 5

[0072] Step 1: Preparation of the nickel-copper alloy nanosheet reaction solution

[0073] The materials were prepared by mixing 2 mmol of copper acetylacetonate, 10 mmol of nickel acetate, 100 mmol of oleylamine and 10 mmol of surfactant trioctylphosphine oxide. Under an argon atmosphere with a gas flow rate of 25 sccm, the mixed solution of copper salt, nickel salt and solvent was stirred at 110 °C for 20 min, and then the surfactant was added. After stirring for another 5 min, the temperature was raised to 240 °C and held for 1 h to obtain a nickel-copper alloy nanosheet solution.

[0074] Step 2: Preparation of nickel-copper alloy nanosheet powder

[0075] Add 150 mL of ethanol to 75 mL of the nickel-copper alloy nanosheet solution obtained in step one to precipitate. Wash the precipitate by high-speed centrifugation at 8000 rpm for 3 min. Dissolve the precipitate in sufficient n-hexane to obtain a solution. Disperse the solution by ultrasonication and wash repeatedly with sufficient ethanol. Vacuum dry the product at 60℃ for 12 h to obtain nickel-copper alloy nanosheet powder.

[0076] Step 3: Preparation of a mixed powder of nickel-copper alloy nanosheets and carbon source

[0077] Mix 0.1g of the nickel-copper alloy nanosheet powder prepared in step two with 1g of melamine, and grind thoroughly to obtain a mixed powder of nickel-copper alloy nanosheets and melamine.

[0078] Step 4: Preparation of carbon-coated nickel-copper alloy nanosheets. The mixed powder of nickel-copper alloy nanosheets obtained in step 3 and melamine was subjected to high-temperature sintering treatment in a protective atmosphere. The protective atmosphere was a nitrogen atmosphere with a gas flow rate of 100 sccm. The temperature was raised to 900℃ at a heating rate of 5℃ / min and held for 1 hour. After cooling to 300℃ at a rate of 10℃ / min, the material was naturally cooled to obtain carbon-coated nickel-copper alloy nanosheets.

[0079] Example 6

[0080] Step 1: Preparation of the nickel-copper alloy nanosheet reaction solution

[0081] The materials were prepared by mixing 2 mmol of copper chloride dihydrate, 10 mmol of nickel stearate, 100 mmol of octadeceneamine and 10 mmol of surfactant trioctylphosphine oxide. Under an argon atmosphere with a gas flow rate of 25 sccm, the mixed solution of copper salt, nickel salt and solvent was stirred at 110 °C for 20 min, and then the surfactant was added. After stirring for another 5 min, the temperature was raised to 200 °C and held for 1 h to obtain a nickel-copper alloy nanosheet solution.

[0082] Step 2: Preparation of nickel-copper alloy nanosheet powder

[0083] Add 150 mL of ethanol to 75 mL of the nickel-copper alloy nanosheet solution obtained in step one to precipitate. Wash the precipitate by high-speed centrifugation at 8000 rpm for 3 min. Dissolve the precipitate in sufficient n-hexane to obtain a solution. Disperse the solution by ultrasonication and wash repeatedly with sufficient ethanol. Vacuum dry the product at 60℃ for 12 h to obtain nickel-copper alloy nanosheet powder.

[0084] Step 3: Preparation of a mixed powder of nickel-copper alloy nanosheets and carbon source

[0085] Mix 0.1g of the nickel-copper alloy nanosheet powder prepared in step two with 0.1g of glucose, and grind thoroughly to obtain a mixed powder of nickel-copper alloy nanosheets and glucose.

[0086] Step 4: Preparation of carbon-coated nickel-copper alloy nanosheets. The mixed powder of nickel-copper alloy nanosheets obtained in step 3 and glucose was subjected to high-temperature sintering treatment in a protective atmosphere. The protective atmosphere was a nitrogen atmosphere with a gas flow rate of 70 sccm. The temperature was raised to 800℃ at a heating rate of 7℃ / min and held for 1 hour. The temperature was then lowered to 300℃ at a rate of 10℃ / min and allowed to cool naturally to obtain carbon-coated nickel-copper alloy nanosheets.

[0087] Example 7

[0088] The phase composition of the nickel-copper alloy nanosheets prepared in Examples 1, 2, and 3 was analyzed using an X'Pert PRO MPD X-ray diffractometer (XRD). The phase composition of the carbon-coated nickel-copper alloy nanosheets prepared in Examples 4, 5, and 6 was also analyzed. Specifically, the powdered sample was poured into a glass slide groove (1.5*1.5cm) until it was just filled, and then placed in the X-ray diffractometer. The X-ray source was Cu Kα (λ=0.15406nm), the scanning range was 10-90°, the scanning rate was 5° / min, the tube voltage was 20-60kV, and the tube current was 10-300mA. Figure 1 The X-ray diffraction patterns are those of the nickel-copper alloy nanosheets prepared in Examples 1, 2 and 3 of this invention. Figure 2 The X-ray diffraction patterns are those of the carbon-coated nickel-copper alloy nanosheets prepared in Examples 4, 5 and 6 of this invention.

[0089] like Figure 1 As shown, the XRD patterns of the nickel-copper alloy nanosheets prepared in Examples 1, 2, and 3 show Ni and Cu peaks, with no other impurity peaks, indicating that the preparation of nickel-copper alloy nanosheets was achieved in this example.

[0090] like Figure 2 As shown, the XRD patterns of the carbon-coated nickel-copper alloy nanosheets prepared in Examples 4, 5, and 6 exhibit Ni, Cu, and C peaks, indicating that the C-coated nickel-copper alloy nanosheets were successfully coated in these examples. The intensity of the C peak increases with the increase of the carbon source mass ratio, indicating that the amount of carbon coated on the surface of the nickel-copper alloy nanosheets gradually increases.

[0091] The microstructure of the nickel-copper alloy nanosheets prepared in Example 2 was observed using a JEM1400FLASH LaB6 transmission electron microscope (TEM). The microstructure of the carbon-coated nickel-copper alloy nanosheets prepared in Examples 4, 5, and 6 was also observed. Specifically, 0.1 g of powdered sample was taken, 2 ml of n-hexane solution was added, and the mixture was sonicated for 10 min to obtain a uniformly dispersed solution system. The solution was then dropped onto a copper grid with an accelerating voltage of 120 kV. Figure 3 This is a transmission electron microscope image of the nickel-copper alloy nanosheets prepared in Example 2 of the present invention; Figure 4 This is a transmission electron microscope image of the carbon-coated nickel-copper alloy nanosheet material prepared in Example 4 of this invention; Figure 5 This is a transmission electron microscope image of the carbon-coated nickel-copper alloy nanosheet material prepared in Example 5 of this invention; Figure 6This is a transmission electron microscope image of the carbon-coated nickel-copper alloy nanosheet material prepared in Example 6 of this invention.

[0092] like Figure 3 As shown, the nickel-copper alloy nanosheets prepared in Example 2 have relatively uniform morphology and size, and are mostly hexagonal.

[0093] like Figure 4 As shown, the carbon-coated nickel-copper alloy nanosheet material prepared in Example 4 catalyzed the formation of carbon nanotube structures when the mass ratio of nickel-copper alloy nanosheet powder to melamine was 1:15. The carbon nanotubes were numerous, and the nickel-copper alloy nanosheets grew inside the carbon nanotubes. The diameter of the carbon nanotubes ranged from 55.38 to 219.74 nm.

[0094] like Figure 5 As shown, the carbon-coated nickel-copper alloy nanosheet material prepared in Example 5 catalyzed the formation of carbon nanotube structures when the mass ratio of nickel-copper alloy nanosheet powder to glucose was 1:10. The nickel-copper alloy nanosheets grew inside the carbon nanotubes, and the diameter of the carbon nanotubes was 40.61-70.65 nm.

[0095] like Figure 6 As shown, the carbon-coated nickel-copper alloy nanosheet material prepared in Example 6, when the mass ratio of nickel-copper alloy nanosheet powder to melamine is 1:1, catalyzes the formation of spherical carbon shell structures on the particle surface, with the diameter of the spherical carbon shells being 50.16-134.72 nm.

[0096] This invention provides a method for preparing nickel-copper alloy nanosheets with controllable morphology and uniform size using an organic liquid phase method. The nickel-copper atomic ratio of the nanosheets can be controlled by adjusting the molar ratio of nickel and copper salts. High-conductivity graphitic carbon is formed through high-temperature sintering of a carbon source, enhancing the material's conductivity. Furthermore, the bonding between the nickel-copper nanosheets and the carbon coating layer can be flexibly adjusted by changing the carbon source ratio. The carbon coating layer comprises carbon nanotubes and spherical carbon shell structures, which facilitates the control of its electromagnetic absorption properties.

[0097] Using an Agilent N5247A vector network analyzer, the carbon-coated nickel-copper alloy nanosheet material prepared in Example 4 was pressed into a ring with paraffin at a filler ratio of 30%. The reflection loss of the sample was then tested, and the absorption performance of the sample at different thicknesses (401 intervals for thicknesses of 1-5 mm) was obtained. Figure 7 This is a reflection loss diagram of the carbon-coated nickel-copper alloy nanosheet material sample prepared in Example 4 of this invention.

[0098] like Figure 7 As shown, when the thickness is 1.8 mm, its minimum reflection loss RL at 13.64 GHz is...min The effective absorption bandwidth (RL < -10dB) is -53.41dB when the thickness is 1.7mm, and the effective absorption bandwidth is 5.32GHz (effective absorption bandwidth frequency range: 12.68-18GHz). The carbon-coated nickel-copper alloy nanosheet material prepared in this embodiment achieves excellent electromagnetic wave absorption performance at a relatively thin thickness by effectively combining the magnetic and electrical media through the coating structure. This allows it to absorb electromagnetic waves in a very small space, solving the problem of strong electromagnetic wave radiation.

[0099] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a carbon-coated nickel-copper alloy nanosheet material, characterized in that, The method comprises: Step one, preparation of nickel-copper alloy nanosheet reaction solution Preparation of raw materials according to a molar ratio of 1-3:10:100:8-10 of copper salt, nickel salt, solvent and surfactant, under an argon atmosphere with a gas flow of 25sccm, the mixed solution of copper salt, nickel salt and solvent is stirred at 110℃ for 20min, then the surfactant is added, and the stirring is continued for 5min, then the temperature is raised to 180-240℃, and the solution is kept at this temperature for 1h to obtain a nickel-copper alloy nanosheet solution; Step two, preparation of nickel-copper alloy nanosheet powder The nickel-copper alloy nanosheet solution obtained in step one is added with ethanol in a volume ratio of 1:2 to precipitate, the obtained precipitate is washed by high-speed centrifugation, the precipitate after centrifugal washing is dissolved with sufficient n-hexane to obtain a dissolved solution, the obtained dissolved solution is ultrasonically dispersed, the obtained product is repeatedly washed with sufficient ethanol, and the obtained product is vacuum dried to obtain nickel-copper alloy nanosheet powder; Step three, preparation of nickel-copper alloy nanosheet and carbon source mixed powder The nickel-copper alloy nanosheet powder prepared in step two is mixed with different mass ratios of carbon source, and after being fully ground, nickel-copper alloy nanosheet and carbon source mixed powder is obtained, wherein the mass ratio of nickel-copper alloy nanosheet powder and carbon source is 1:1 to 1:20; Step four, preparation of carbon-coated nickel-copper alloy nanosheet material The mixed powder of nickel-copper alloy nanosheet and carbon source obtained in step three is subjected to high-temperature sintering treatment in a protective atmosphere to obtain carbon-coated nickel-copper alloy nanosheet material, the high-temperature sintering treatment includes: heating at a heating rate of 5-10℃ / min to 700-900℃ and keeping for 1-3h, and then cooling to 300℃ at a rate of 10℃ / min and naturally cooling. 2.The method of claim 1, wherein the carbon-coated nickel-copper alloy nanoplatelet material is prepared by the steps of: preparing a nickel-copper alloy nanoplatelet material; and coating the nickel-copper alloy nanoplatelet material with carbon. In step one, the copper salt is copper chloride dihydrate or copper acetylacetonate, the nickel salt is one of acetylacetonate nickel, nickel stearate or nickel acetate, the solvent is one of oleylamine, octadecenylamine or N'N-dimethylformamide, and the surfactant is one of tri-n-octyl phosphine, triphenyl phosphine or trioctyl phosphine oxide.

3. The method of claim 1, wherein the carbon-coated nickel-copper alloy nanoplatelet material is prepared by the steps of: preparing a nickel-copper alloy nanoplatelet material; and coating the nickel-copper alloy nanoplatelet material with carbon. In step two, the centrifugal speed of high-speed centrifugal washing is 8000rpm, and the time of high-speed centrifugal washing is 3min.

4. The method of claim 1, wherein the carbon-coated Ni-Cu alloy nanoplatelet material is prepared by the steps of: preparing a solution of nickel chloride and copper chloride; adding a reducing agent to the solution; and adding a carbon source to the solution. In step two, the temperature of vacuum drying treatment is 60℃, and the vacuum drying time is 12h.

5. The method for preparing carbon-coated nickel-copper alloy nanosheets according to claim 1, characterized in that, In step three, the carbon source is one of melamine, glucose or dopamine.

6. The method of claim 1, wherein the carbon-coated Ni-Cu alloy nanoplatelet material is prepared by the steps of: preparing a solution of nickel chloride and copper chloride; adding a reducing agent to the solution; and adding a carbon source to the solution. In step four, the protective atmosphere is a nitrogen atmosphere with a gas flow of 50-100sccm.

7. A carbon-coated nickel-copper alloy nanoplatelet material, characterized in that, The carbon-coated nickel-copper alloy nanosheet material is prepared according to the method of any one of claims 1-6.

8. The carbon-coated nickel-copper alloy nanoplatelet material of claim 7, wherein, In the carbon-coated nickel-copper alloy nanosheet material, the carbon is in the form of carbon nanotubes or spherical carbon shell structure to coat the nickel-copper alloy nanosheet.

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