Metal-graphene nanofiber membrane composite material, preparation method and application thereof

Abstract

This invention relates to a metal-graphene nanofiber membrane composite material, its preparation method, and its application. The preparation method includes: using a dispersion of graphene oxide, a polymer, and a surfactant as a spinning solution, electrospinning to obtain a graphene oxide nanofiber membrane, then reducing it to obtain a graphene nanofiber membrane, and then carbonizing it with urea under a protective atmosphere to obtain a hydrophilic nitrogen-doped graphene nanofiber membrane. The carbonization temperature is 500℃-700℃. The hydrophilic nitrogen-doped graphene nanofiber membrane is then sensitized and activated, followed by chemical plating in a chemical plating solution to obtain the metal-graphene nanofiber membrane composite material. This invention achieves nitrogen doping simultaneously with carbonization and controls the type of nitrogen doping. Chemical plating can be used to composite carbon fiber membranes with metals, resulting in a lightweight, highly conductive, and well-bonded metal-graphene nanofiber membrane composite material.

Description

Technical Field

[0001] This invention relates to the field of metal-carbon composite materials, and in particular to metal-graphene nanofiber membrane composite materials, their preparation methods, and applications. Background Technology

[0002] Carbon fibers, prepared by oxidation and carbonization processes using polypropylene fibers, pitch fibers, or viscose fibers, possess properties such as high specific strength, high specific modulus, good toughness, low density, high temperature resistance, corrosion resistance, friction resistance, electrical and thermal conductivity, and low coefficient of thermal expansion. Combining carbon fibers with metals can reduce the weight of metal materials while improving their flexibility.

[0003] However, carbon fiber has a high surface inertness and low surface energy, lacks chemically active bonds, has low reactivity, poor bonding with metals, and numerous surface defects, which directly affect the mechanical properties of the composite material and limit its high performance. Furthermore, due to the poor wettability of carbon fiber at room temperature and its poor compatibility with metals, the preparation of the composite material also presents significant difficulties. Summary of the Invention

[0004] Therefore, it is necessary to provide a metal-graphene nanofiber membrane composite material, its preparation method, and its application to address the above problems. The preparation method achieves nitrogen doping during carbonization and controls the type of doped nitrogen. Chemical plating can be used to achieve the composite of the fiber membrane and the metal, resulting in a lightweight, highly conductive, and well-bonded metal-graphene nanofiber membrane composite material.

[0005] A method for preparing a metal-graphene nanofiber membrane composite material includes the following steps:

[0006] Electrospinning was performed using a dispersion of graphene oxide, polymer, and surfactant as the spinning solution to obtain graphene oxide nanofiber membranes.

[0007] The graphene oxide nanofiber membrane was reduced to obtain a graphene nanofiber membrane.

[0008] The graphene nanofiber membrane is carbonized with urea under a protective atmosphere to obtain a hydrophilic nitrogen-doped graphene nanofiber membrane, wherein the carbonization temperature is 500℃-700℃.

[0009] The hydrophilic nitrogen-doped graphene nanofiber membrane was activated and sensitized, and then chemically plated in a chemical plating solution to obtain a metal-graphene nanofiber membrane composite material.

[0010] In one embodiment, the graphene oxide has a mass fraction of 8%-12% in the dispersion, the polymer has a mass fraction of 8%-12% in the dispersion, and the surfactant has a mass fraction of 0.8%-1.2% in the dispersion.

[0011] In one embodiment, in the step of carbonizing the graphene nanofiber membrane and urea under a protective atmosphere, the mass ratio of the graphene nanofiber membrane to the urea is 1:0.7-1:1.1.

[0012] In one embodiment, the carbonization process takes 1 to 1.5 hours and the heating rate is 1.8°C / min to 2.5°C / min.

[0013] In one embodiment, the sensitizer used in the sensitization treatment is selected from stannous chloride.

[0014] In one embodiment, the activator used in the activation treatment is selected from at least one of palladium chloride and platinum chloride.

[0015] In one embodiment, the electroless plating solution is selected from at least one of electroless copper plating solution, electroless nickel plating solution, electroless silver plating solution, electroless tin plating solution, or electroless gold plating solution.

[0016] A metal-graphene nanofiber membrane composite material prepared by the aforementioned preparation method, the metal-graphene nanofiber membrane composite material comprising a nitrogen-doped graphene nanofiber membrane and a metal coated on the surface of the nitrogen-doped graphene nanofiber membrane, wherein the molar percentage of nitrogen atoms in the nitrogen-doped graphene nanofiber membrane is 4%-7%, the molar percentage of pyrrole nitrogen in the nitrogen atoms is 40%-60%, and the molar percentage of pyridine nitrogen is 30%-50%.

[0017] In one embodiment, the metal is copper.

[0018] An electromagnetic shielding element prepared using the aforementioned metal-graphene nanofiber membrane composite material.

[0019] In the preparation method of this invention, graphene oxide nanofiber membranes are first prepared using electrospinning, then graphene nanofiber membranes are obtained through reduction, and then the graphene nanofiber membranes are carbonized. Urea is added during the carbonization step; the thermal decomposition of urea generates a nitrogen-rich atmosphere, allowing nitrogen doping to occur simultaneously during the carbonization process. Furthermore, by controlling the carbonization temperature, the doped nitrogen in the graphene nanofiber membrane is primarily pyrrole nitrogen and pyridine nitrogen, thus giving the nitrogen-doped graphene nanofiber membrane hydrophilicity, which is beneficial for electroless plating. Therefore, the preparation method of this invention achieves electroless metal plating on the surface of nitrogen-doped graphene nanofiber membranes after low-temperature carbonization without any additional modification steps. The process is simple, the conditions are controllable, and the resulting metal-graphene nanofiber membrane composite material is lightweight, has high conductivity, and good adhesion, exhibiting excellent performance and can be widely used in electromagnetic shielding and other fields. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 SEM image of the hydrophilic nitrogen-doped graphene nanofiber membrane obtained in Example 1;

[0022] Figure 2 The image shows the nitrogen peaks of the XPS of the hydrophilic nitrogen-doped graphene nanofiber membrane obtained in Example 1, where A represents pyridine nitrogen, B represents pyrrole nitrogen, C represents graphitic nitrogen, and D represents adsorbed nitrogen.

[0023] Figure 3 SEM images of the hydrophilic nitrogen-doped graphene nanofiber membrane after activation and sensitization treatments in Example 1.

[0024] Figure 4 The image shows a SEM image of the copper-graphene nanofiber membrane composite material obtained in Example 1. Detailed Implementation

[0025] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0027] In this invention, numerical ranges are involved. Unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe features or characteristics, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0028] The method for preparing the metal-graphene nanofiber membrane composite material provided by the present invention includes the following steps:

[0029] S1, using a dispersion of graphene oxide, polymer and surfactant as spinning solution, electrospinning is performed to obtain graphene oxide nanofiber membrane.

[0030] S2, the graphene oxide nanofiber membrane is reduced to obtain a graphene nanofiber membrane.

[0031] S3, the graphene nanofiber membrane is carbonized with urea under a protective atmosphere to obtain a hydrophilic nitrogen-doped graphene nanofiber membrane, wherein the carbonization temperature is 500℃-700℃.

[0032] S4. The hydrophilic nitrogen-doped graphene nanofiber membrane is sensitized and activated, and then chemically plated in a chemical plating solution to obtain a metal-graphene nanofiber membrane composite material.

[0033] In steps S1 and S2 of this invention, graphene oxide nanofiber membranes are first prepared by electrospinning, and then graphene nanofiber membranes are obtained by reduction. First, graphene nanofiber membranes have higher flexibility and strength than carbon fiber membranes, which is beneficial to improving the mechanical properties of composite materials. Second, graphene oxide spontaneously generates a large number of wrinkled structures during electrospinning. This structure is beneficial to the uniform loading of catalyst particles during activation, which in turn is beneficial to the more uniform and dense formation of metal on the surface of the fiber membrane. Furthermore, the maximum diameter of graphene nanofiber membranes is only about 1 μm, with a larger specific surface area, which can load more metal and improve the conductivity of composite materials. When applied to the field of electromagnetic shielding, the electromagnetic shielding effect is better.

[0034] In step S1, the mass fraction of graphene oxide in the dispersion is preferably 8%-12%, and the sheet size of graphene oxide is 5μm-30μm. Graphene oxide of this size is more likely to be bent and stacked into a fiber membrane under the action of surface tension, which is more conducive to the uniform and dense formation of metal on the surface of the fiber membrane.

[0035] The polymer in the dispersion is preferably 8%-12% by mass. Higher molecular weight polymers provide sufficient chain entanglement, improve the solution stretching properties, and produce graphene fiber membranes with uniform morphology. Therefore, the weight-average molecular weight of the polymer is preferably greater than or equal to 10. 6 The polymer is preferably one or more of sodium polyacrylate, PVA, and PEO.

[0036] The surfactant is preferably one or more of Triton-X100 and SDS, and the mass fraction of the surfactant in the dispersion is preferably 0.8%-1.2%.

[0037] Using the spinning solution of the present invention, a uniform and high-performance graphene oxide nanofiber membrane can be obtained during electrospinning.

[0038] This invention does not impose requirements on the process conditions of electrospinning. Preferably, the temperature of the electrospinning chamber is adjusted to 45℃-60℃, the humidity to 5%-15%, the extrusion rate to 0.01±0.002ml / min, the distance between the collecting roller and the metal needle to 10cm-20cm, and the voltage of the spinning machine to 15KV-20KV.

[0039] In step S2, the method of reducing the graphene oxide nanofiber membrane is not limited. Preferably, a reducing agent such as HI is used to reduce the graphene oxide nanofiber membrane. In the reduction treatment step, the temperature is preferably 65℃-95℃ and the time is preferably 6h-8h.

[0040] In step S3 of this invention, urea is added during the carbonization treatment of the graphene nanofiber membrane. The thermal decomposition of urea generates a nitrogen-rich atmosphere, allowing the graphene nanofiber membrane to achieve nitrogen doping simultaneously during the polymer removal process, which is beneficial for improving the conductivity of the graphene nanofiber membrane. Furthermore, the thermal decomposition of urea produces different types of molecules, which can cause the nitrogen-doped graphene nanofiber membrane to exhibit different hydrophobic and hydrophilic properties. This invention controls the carbonization temperature so that the doped nitrogen in the graphene nanofiber membrane is mainly pyrrole nitrogen and pyridine nitrogen, thereby giving the nitrogen-doped graphene nanofiber membrane hydrophilicity, which is beneficial for achieving electroless plating.

[0041] Optionally, in the step of carbonizing the graphene nanofiber membrane and urea under a protective atmosphere, the mass ratio of the graphene nanofiber membrane to the urea is preferably 1:0.7-1:1.1, the carbonization time is 1 hour to 1.5 hours, and the heating rate is 1.8-2.5℃ / min, which can effectively achieve nitrogen doping while ensuring the hydrophilicity of the graphene nanofiber membrane.

[0042] Furthermore, the protective atmosphere can be selected from inert gases, such as argon and nitrogen.

[0043] Because the graphene nanofiber membrane obtained by this invention has a small diameter, the requirements for electroless plating are higher. Therefore, in step S4 of this invention, the hydrophilic nitrogen-doped graphene nanofiber membrane is first sensitized and activated, and then electroless plating is performed.

[0044] Specifically, in step S4, the hydrophilic nitrogen-doped graphene nanofiber membrane is first sensitized. This allows a sensitizer to be adsorbed onto the surface of the hydrophilic nitrogen-doped graphene nanofiber membrane, ensuring a reduction reaction occurs during activation. Optionally, the hydrophilic nitrogen-doped graphene nanofiber membrane can be placed in a sensitizer solution, or the sensitizer can be formed on the hydrophilic nitrogen-doped graphene nanofiber membrane by spraying or other methods, so that a sensitizer layer is adsorbed onto the surface of the hydrophilic nitrogen-doped graphene nanofiber membrane. Optionally, the sensitizer is selected from stannous chloride.

[0045] After sensitization treatment, the hydrophilic nitrogen-doped graphene nanofiber film with a sensitizer on its surface is then activated. During activation, the activator is reduced by the sensitizer, generating catalyst particles that adhere to the surface of the hydrophilic nitrogen-doped graphene nanofiber film, forming a catalytically active layer. In the subsequent electroless plating step, this allows the electroless plating to proceed spontaneously. Optionally, the hydrophilic nitrogen-doped graphene nanofiber film with a sensitizer on its surface can be placed in an activator solution, or the activator can be formed on the hydrophilic nitrogen-doped graphene nanofiber film with a sensitizer on its surface by spraying or other methods. Optionally, the activator is selected from at least one of palladium chloride and platinum chloride.

[0046] For example, a hydrophilic nitrogen-doped graphene nanofiber membrane is first sensitized with argon tin chloride, causing a layer of stannous chloride to be adsorbed on the surface of the hydrophilic nitrogen-doped graphene nanofiber membrane. Then, when palladium chloride is used for activation, palladium ions are reduced by the stannous ions adsorbed on the surface of the hydrophilic nitrogen-doped graphene nanofiber membrane to generate elemental palladium. This elemental palladium then adheres to the surface of the hydrophilic nitrogen-doped graphene nanofiber membrane as colloidal particles, forming a catalytically active layer. In the subsequent electroless plating step, the elemental palladium particles in the catalytically active layer can serve as catalytic centers, enabling the electroless plating to proceed spontaneously.

[0047] The chemical plating method provided by this invention is universal and applicable to the chemical plating of various metals on the surface of graphene nanofiber membrane materials. Optionally, the chemical plating solution is selected from at least one of chemical copper plating solution, chemical nickel plating solution, chemical silver plating solution, chemical tin plating solution, or chemical gold plating solution. For example, when the chemical plating solution is a chemical copper plating solution, a copper-graphene nanocomposite fiber membrane material can be obtained; when the chemical plating solution is a chemical nickel plating solution, a nickel-graphene nanocomposite fiber membrane material can be obtained.

[0048] The present invention also provides a metal-graphene nanofiber composite membrane material prepared by the aforementioned preparation method, wherein the metal-graphene nanofiber composite membrane material comprises a nitrogen-doped graphene nanofiber membrane and a metal coated on the surface of the nitrogen-doped graphene nanofiber membrane, wherein the molar percentage of nitrogen atoms in the nitrogen-doped graphene nanofiber membrane is 4%-7%, the molar percentage of pyrrole nitrogen in the nitrogen atoms is 40%-60%, and the molar percentage of pyridine nitrogen is 30%-50%.

[0049] The metal-graphene nanofiber membrane composite material of the present invention is lightweight, has high conductivity and good bonding strength, and has excellent performance, and can be widely used in electromagnetic shielding and other fields.

[0050] Optionally, the metal-graphene nanofiber membrane composite material is a copper-graphene nanofiber membrane composite material, which is very suitable for preparing electromagnetic shielding components, and its absolute shielding effectiveness can reach 90 dB·cm in the range of 8.2 GHz-12.4 GHz. 3 / g.

[0051] The present invention also provides an electromagnetic shielding element prepared using the aforementioned metal-graphene nanofiber membrane composite material, such as an electromagnetic shielding element prepared using a copper-graphene nanofiber membrane composite material, which has excellent electromagnetic shielding effect.

[0052] The following specific embodiments will further illustrate the metal-graphene nanofiber membrane composite material, its preparation method, and its application.

[0053] Example 1

[0054] Take 6g of sodium polyacrylate (weight average molecular weight 10) 6 A mixture of 20.0 mg / g graphene oxide solution (graphene oxide sheet diameter of 30 μm) and 0.024 g of surfactant Triton-X100 was added, and the mixture was stirred evenly using a planetary mixer to obtain a dispersion. The dispersion contained 10% by mass of graphene oxide, 10% by mass of sodium polyacrylate, and 1% by mass of Triton-X100.

[0055] The above dispersion was used as the spinning solution. 10g of the spinning solution was taken using a syringe and placed into an electrospinning machine. A metal needle was attached to the syringe, perpendicular to the collecting roller, and connected to the positive terminal of the spinneret voltage. The collecting roller was wrapped with a copper mesh to collect all the prepared graphene oxide nanofiber membrane on the mesh. The electrospinning chamber temperature was adjusted to 45℃, humidity to 10%, extrusion rate to 0.01±0.002mL / min, distance between the collecting roller and the metal needle to 20cm, and spinneret voltage to 15KV. After 4 hours, a 10μm thick graphene oxide nanofiber membrane was obtained on the collecting roller.

[0056] The graphene oxide nanofiber membrane was peeled off from the surface of the copper mesh and reduced with HI at 95°C for 6 hours to obtain the graphene nanofiber membrane.

[0057] Graphene nanofiber membranes and urea were placed in a tube furnace at a mass ratio of 1:1, argon gas was introduced, and the temperature was increased at a rate of 2 °C / min. The mixture was then treated at 700 °C for 1 hour to obtain a hydrophilic nitrogen-doped graphene nanofiber membrane with a contact angle of 15° and a conductivity of 7.6 × 10⁻⁶. 2 S / m.

[0058] Depend on Figure 1 It can be seen that the hydrophilic nitrogen-doped graphene nanofiber membrane has obvious fibrous structure and a relatively smooth surface morphology, while also being composed of… Figure 2 As shown, the XPS of the hydrophilic nitrogen-doped graphene nanofiber membrane obtained in this embodiment exhibits a clear nitrogen peak pattern, mainly consisting of pyrrole nitrogen and pyridine nitrogen, with a relatively low graphitic nitrogen content. Detection revealed that the molar percentage of nitrogen atoms in the nitrogen-doped graphene nanofiber membrane was 6.8%, of which the molar percentage of pyrrole nitrogen was 41%, pyridine nitrogen was 36%, graphitic nitrogen was 20%, and adsorbed nitrogen was 3%.

[0059] Hydrophilic nitrogen-doped graphene nanofiber membranes were immersed in a 20 g / L stannous chloride solution at 30°C for 10 minutes, followed by thorough rinsing. Then, they were immersed in a 0.5 g / L palladium chloride solution at 30°C for 10 minutes, followed by thorough rinsing, completing the sensitization and activation treatments. Figure 3 It can be seen that after sensitization and activation treatment, the surface of the hydrophilic nitrogen-doped graphene nanofiber membrane is covered with palladium particles.

[0060] A solution was prepared using 8 g / L copper sulfate, 1 g / L nickel sulfate, 40 g / L sodium hypophosphite, 20 g / L citric acid, 30 g / L boric acid, 100 mg / L PEG, and 4 mg / L potassium ferrocyanide. The pH was then adjusted to 9.5 with sodium hydroxide to obtain a chemical copper plating solution. The hydrophilic nitrogen-doped graphene nanofiber membrane, which had undergone sensitization and activation treatment, was then placed in the chemical copper plating solution and heated to 65°C for 10 minutes to obtain a copper-graphene nanofiber membrane composite material.

[0061] Depend on Figure 4 It can be seen that the copper grains in the copper-graphene nanofiber membrane composite material obtained in this embodiment are uniform and dense. The density of the copper-graphene nanofiber membrane composite material was measured to be 0.448 g / cm³. 3 It has only 5% the conductivity of pure copper, and its electrical conductivity is as high as 3×10⁻⁶ 4 S / m.

[0062] Example 2

[0063] The only difference between Example 2 and Example 1 is that the carbonization temperature is 600°C.

[0064] The nitrogen-doped graphene nanofiber film obtained in this embodiment has a nitrogen atom molar percentage of 5.8%, of which pyrrole nitrogen has a molar percentage of 58%, pyridine nitrogen has a molar percentage of 39%, adsorbed nitrogen has a molar percentage of 3%, and no graphitic nitrogen is present. Its contact angle is 12°, and its conductivity is 3.40 × 10⁻⁶. 2 The density of the obtained copper-graphene nanofiber membrane composite material was 0.45 g / cm³. 3 Its conductivity is as high as 2.83×10⁻⁶. 4 S / m.

[0065] Example 3

[0066] The only difference between Example 3 and Example 1 is that the carbonization temperature is 500°C.

[0067] The nitrogen-doped graphene nanofiber film obtained in this embodiment has a nitrogen atom molar percentage of 4.7%, of which pyrrole nitrogen accounts for 59%, pyridine nitrogen accounts for 38%, adsorbed nitrogen accounts for 3%, and there is no graphitic nitrogen. Its contact angle is 10°, and its conductivity is 2.15 × 10⁻⁶. 2 The density of the obtained copper-graphene nanofiber membrane composite material was 0.45 g / cm³. 3 Its conductivity is as high as 2.78×10⁻⁶. 4 S / m.

[0068] Comparative Example 1

[0069] The only difference between Comparative Example 1 and Example 1 is that urea was not added in the carbonization process.

[0070] The nitrogen-doped graphene nanofiber film obtained in this comparative example has a contact angle of 125° and a conductivity of 7.51 × 10⁻⁶. 2 S / m.

[0071] Comparative Example 2

[0072] The only difference between Comparative Example 2 and Example 1 is that the carbonization temperature is 900°C.

[0073] The nitrogen-doped graphene nanofiber film obtained in this comparative example has a nitrogen atom molar percentage of 5.8%, of which pyrrole nitrogen accounts for 9%, pyridine nitrogen for 53%, and graphitic nitrogen for 38%. It exhibits no adsorbed nitrogen, a contact angle of 130°, and a conductivity of 2.02 × 10⁻⁶. 3 S / m.

[0074] Comparative Example 3

[0075] The only difference between Comparative Example 3 and Example 1 is that the carbonization temperature is 1100°C.

[0076] The nitrogen-doped graphene nanofiber film obtained in this comparative example has a nitrogen atom molar percentage of 4.6%, of which pyridine nitrogen accounts for 36% and graphitic nitrogen accounts for 64%. It contains no pyrrole nitrogen or adsorbed nitrogen, has a contact angle of 140°, and a conductivity of 4.07 × 10⁻⁶. 3 S / m.

[0077] The graphene nanofiber membrane obtained in Example 1 and the copper-graphene nanofiber membrane composite material obtained in Example 1 were cut into 23mm*10.2mm sizes and subjected to absolute shielding effectiveness tests. The results showed that the graphene nanofiber membrane had an absolute shielding effectiveness of 75dB·cm in the 8.2-12.4GHz range. 3 / g; Copper-graphene nanofiber membrane composites reach up to 90 dB·cm in the 8.2–12.4 GHz range. 3 / g; for the same size, copper mesh requires only 25 dB·cm in the 8.2-12.4 GHz range. 3 / g.

[0078] Example 4

[0079] The difference between Example 4 and Example 1 is that a solution was prepared using 30 g / L nickel sulfate, 30 g / L sodium hypophosphite, 25 g / L sodium citrate, 15 g / L sodium acetate, 6 g / L lactic acid, 0.01 g / L sodium dodecyl sulfate, and 1 g / L urea. The pH was adjusted to 5 with sulfuric acid to obtain a chemical nickel plating solution. The hydrophilic nitrogen-doped graphene nanofiber membrane, which had undergone sensitization and activation treatments, was then placed in the chemical nickel plating solution and heated to 80°C for 10 minutes to obtain a nickel-graphene nanofiber membrane composite material.

[0080] After testing, the density of the nickel-graphene nanofiber membrane composite material obtained in this embodiment was 0.834 g / cm³. 3 Its conductivity is as high as 1.94 × 10⁻⁶. 4 S / m.

[0081] Example 5

[0082] The difference between Example 5 and Example 1 is that, firstly, a silver salt solution is prepared, specifically consisting of 10 g / L silver nitrate, 60 mL / L ammonia, 20 mL / L ethylenediamine, 6 g / L potassium hydroxide, and 70 mg / L sodium thiosulfate pentahydrate. Then, a reducing agent solution is prepared, specifically consisting of 8 g / L glucose, 2.5 g / L potassium sodium tartrate, 40 mL / L ethanol, and 75 mg / L PEG1000. The two solutions are mixed to obtain a chemical silver plating solution. The hydrophilic nitrogen-doped graphene nanofiber membrane, which has undergone sensitization and activation treatment, is then placed in the chemical silver plating solution and reacted at room temperature for 10 minutes to obtain a silver-graphene nanofiber membrane composite material.

[0083] After testing, the density of the silver-graphene nanofiber membrane composite material obtained in this embodiment was 0.237 g / cm³. 3 Its conductivity is as high as 4.52×10⁻⁶. 4 S / m.

[0084] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a metal-graphene nanofiber membrane composite material, characterized in that, Includes the following steps: Electrospinning was performed using a dispersion of graphene oxide, a polymer, and a surfactant as the spinning solution to obtain a graphene oxide nanofiber membrane. The polymer was selected from one or more of sodium polyacrylate, PVA, and PEO. The graphene oxide nanofiber membrane was reduced to obtain a graphene nanofiber membrane. The graphene nanofiber membrane is carbonized with urea under a protective atmosphere to obtain a hydrophilic nitrogen-doped graphene nanofiber membrane, wherein the carbonization temperature is 500℃-700℃. The hydrophilic nitrogen-doped graphene nanofiber membrane is sensitized and activated, and then chemically plated in a chemical plating solution to obtain a metal-graphene nanofiber membrane composite material, which is used to prepare an electromagnetic shielding element.

2. The method for preparing the metal-graphene nanofiber membrane composite material according to claim 1, characterized in that, The graphene oxide has a mass fraction of 8%-12% in the dispersion, the polymer has a mass fraction of 8%-12% in the dispersion, and the surfactant has a mass fraction of 0.8%-1.2% in the dispersion.

3. The method for preparing the metal-graphene nanofiber membrane composite material according to claim 1, characterized in that, In the step of carbonizing the graphene nanofiber membrane and urea under a protective atmosphere, the mass ratio of the graphene nanofiber membrane to the urea is 1:0.7-1:1.

1.

4. The method for preparing the metal-graphene nanofiber membrane composite material according to claim 1, characterized in that, The carbonization process takes 1 to 1.5 hours and the heating rate is 1.8°C / min to 2.5°C / min.

5. The method for preparing the metal-graphene nanofiber membrane composite material according to claim 1, characterized in that, The sensitizer used in the sensitization treatment is selected from stannous chloride.

6. The method for preparing the metal-graphene nanofiber membrane composite material according to claim 1, characterized in that, The activator used in the activation treatment is selected from at least one of palladium chloride and platinum chloride.

7. The method for preparing the metal-graphene nanofiber membrane composite material according to claim 1, characterized in that, The electroless plating solution is selected from at least one of electroless copper plating solution, electroless nickel plating solution, electroless silver plating solution, electroless tin plating solution, or electroless gold plating solution.

8. A metal-graphene nanofiber membrane composite material prepared by the preparation method according to any one of claims 1 to 7, characterized in that, The metal-graphene nanofiber membrane composite material includes a nitrogen-doped graphene nanofiber membrane and a metal coated on the surface of the nitrogen-doped graphene nanofiber membrane, wherein the molar percentage of nitrogen atoms in the nitrogen-doped graphene nanofiber membrane is 4%-7%, the molar percentage of pyrrole nitrogen in the nitrogen atoms is 40%-60%, and the molar percentage of pyridine nitrogen is 30%-50%.

9. The metal-graphene nanofiber membrane composite material according to claim 8, characterized in that, The metal is copper.

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