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

Abstract

The invention relates to a metal-graphene nanofiber membrane composite material and a preparation method and application thereof.The preparation method comprises the steps that a dispersion liquid of graphene oxide, a polymer and a surfactant serves as a spinning solution, a graphene oxide nanofiber membrane is obtained through electrostatic spinning, then a graphene nanofiber membrane is obtained through reduction, and the metal-graphene nanofiber membrane composite material is obtained. The preparation method comprises the following steps: preparing a hydrophilic nitrogen-doped graphene nanofiber membrane, performing carbonization treatment on the hydrophilic nitrogen-doped graphene nanofiber membrane and urea in a protective atmosphere at 500-700 DEG C to obtain the hydrophilic nitrogen-doped graphene nanofiber membrane, performing sensitization treatment and activation treatment on the hydrophilic nitrogen-doped graphene nanofiber membrane, and performing chemical plating on the hydrophilic nitrogen-doped graphene nanofiber membrane in a chemical plating solution to obtain the hydrophilic nitrogen-doped graphene nanofiber membrane. The metal-graphene nanofiber membrane composite material is obtained. Nitrogen doping is achieved while carbonization treatment is conducted, the type of doped nitrogen is controlled, compounding of the carbon fiber membrane and metal can be achieved through chemical plating, and the metal-graphene nanofiber membrane composite material which is light in mass, high in electric conductivity and excellent in binding force is obtained.

Description

Technical Field

[0001] The present invention relates to the field of metal-carbon composite materials, and in particular to a metal-graphene nanofiber membrane composite material and a preparation method and application thereof. Background Art

[0002] Carbon fibers prepared from polypropylene fibers, asphalt fibers or viscose fibers through oxidation and carbonization processes have the properties of high specific strength, high specific modulus, good toughness, low density, high temperature resistance, corrosion resistance, friction resistance, electrical and thermal conductivity, and small expansion coefficient. Composite carbon fibers with metals can reduce the weight of metal materials while improving their flexibility.

[0003] However, carbon fiber has a large inert surface, low surface energy, lacks chemically active chemical bonds, has low reactivity, poor bonding with metals, and has many surface defects, which directly affect the mechanical properties of the composite material and limit its high performance. In addition, since carbon fiber has poor wettability at room temperature and poor compatibility with metals, there are obvious difficulties in the preparation of composite materials. Summary of the invention

[0004] Based on this, it is necessary to provide a metal-graphene nanofiber membrane composite material and its preparation method and application to address the above problems. The preparation method realizes nitrogen doping during carbonization treatment and controls the type of doped nitrogen. Chemical plating can be used to realize the composite of fiber membrane and metal to obtain a metal-graphene nanofiber membrane composite material with light weight, high conductivity and excellent bonding strength.

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

[0006] Using a dispersion of graphene oxide, polymer and surfactant as a spinning solution, electrospinning is performed to obtain a graphene oxide nanofiber membrane;

[0007] The graphene oxide nanofiber membrane is subjected to a reduction treatment to obtain a graphene nanofiber membrane;

[0008] Carrying out a carbonization treatment on the graphene nanofiber membrane and urea under a protective atmosphere to obtain a hydrophilic nitrogen-doped graphene nanofiber membrane, wherein the temperature of the carbonization treatment is 500° C.-700° C.;

[0009] The hydrophilic nitrogen-doped graphene nanofiber membrane is subjected to activation treatment and sensitization treatment, and then chemically plated in a chemical plating solution to obtain a metal-graphene nanofiber membrane composite material.

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

[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 treatment time is 1 hour 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 activating agent used in the activation treatment is selected from at least one of palladium chloride and platinum chloride.

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

[0016] A metal-graphene nanofiber membrane composite material prepared by the preparation method, the metal-graphene nanofiber membrane composite 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 pyrrolic nitrogen in the nitrogen atoms is 40%-60%, and the molar percentage of pyridinic nitrogen is 30%-50%.

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

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

[0019] In the preparation method of the present invention, an electrostatic spinning method is first used to prepare an oxidized graphene nanofiber membrane, and then the graphene nanofiber membrane is obtained by reduction, and then the graphene nanofiber membrane is carbonized, and urea is added in the step of carbonization, and urea is thermally decomposed to produce a nitrogen-rich atmosphere, so that the graphene nanofiber membrane is nitrogen-doped during the carbonization process, and at the same time, by controlling the temperature of the carbonization treatment, the doped nitrogen in the graphene nanofiber membrane is mainly pyrrole nitrogen and pyridine nitrogen, so that the nitrogen-doped graphene nanofiber membrane has hydrophilicity, which is conducive to the realization of chemical plating. Therefore, the preparation method of the present invention realizes chemical metal plating on the surface of the nitrogen-doped graphene nanofiber membrane after carbonization treatment at a lower temperature without any additional modification steps, the process is simple, the conditions are controllable, and the obtained metal-graphene nanofiber membrane composite material is light in weight, high in conductivity and good in bonding, and has excellent performance, and can be widely used in electromagnetic shielding and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

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

[0022] Figure 2 This is the nitrogen peak diagram of the XPS of the hydrophilic nitrogen-doped graphene nanofiber membrane obtained in Example 1, wherein A is pyridinic nitrogen, B is pyrrolic nitrogen, C is graphitic nitrogen, and D is adsorbed nitrogen;

[0023] Figure 3 This is a SEM image of the hydrophilic nitrogen-doped graphene nanofiber membrane after activation treatment and sensitization treatment in Example 1;

[0024] Figure 4 This is the SEM image of the copper-graphene nanofiber membrane composite material obtained in Example 1. DETAILED DESCRIPTION

[0025] For ease of understanding of the present invention, the present invention 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. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific implementation methods or embodiments, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, and the combinations include any two related listed items, any more related listed items, or all related listed items.

[0027] In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

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

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

[0030] S2, reducing the graphene oxide nanofiber membrane to obtain a graphene nanofiber membrane;

[0031] S3, carbonizing the graphene nanofiber membrane and urea under a protective atmosphere to obtain a hydrophilic nitrogen-doped graphene nanofiber membrane, wherein the temperature of the carbonization treatment is 500° C.-700° C.;

[0032] S4, subjecting the hydrophilic nitrogen-doped graphene nanofiber membrane to sensitization and activation treatments, and then subjecting the hydrophilic nitrogen-doped graphene nanofiber membrane to chemical plating in a chemical plating solution to obtain a metal-graphene nanofiber membrane composite material.

[0033] In step S1 and step S2 of the present invention, an electrostatic spinning method is first used to prepare a graphene oxide nanofiber membrane, and then the graphene nanofiber membrane is obtained by reduction. First, the graphene nanofiber membrane has higher flexibility and strength than the carbon fiber membrane, which is beneficial to improving the mechanical properties of the composite material. Secondly, graphene oxide will spontaneously generate a large number of wrinkled structures during the electrostatic spinning process. This structure is beneficial to the uniform loading of catalyst particles during the activation process, and then to the more uniform and dense formation of metal on the surface of the fiber membrane. Furthermore, the maximum diameter of the graphene nanofiber membrane is only about 1 μm, and the specific surface area is larger, so it can load more metal, improve the conductivity of the composite material, and have a better electromagnetic shielding effect when applied to the electromagnetic shielding field.

[0034] In step S1, the mass fraction of the graphene oxide in the dispersion is preferably 8%-12%, and the flake size of the graphene oxide is 5μm-30μm. Graphene oxide of this size is easier to bend and stack 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 mass fraction of the polymer in the dispersion is preferably 8%-12%. A polymer with a higher molecular weight can provide sufficient chain entanglement, improve the solution tensile properties, and prepare a graphene fiber membrane 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] By using the spinning solution of the present invention, a uniform graphene oxide nanofiber membrane with excellent performance can be obtained in the electrostatic spinning process.

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

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

[0040] In step S3 of the present invention, urea is added when the graphene nanofiber membrane is carbonized. The urea is thermally decomposed to produce a nitrogen-rich atmosphere, so that the graphene nanofiber membrane is nitrogen-doped during the process of carbonization to remove the polymer, which is beneficial to improving the conductivity of the graphene nanofiber membrane. In addition, the urea is thermally decomposed to produce different types of molecules, which can make the nitrogen-doped graphene nanofiber membrane present different hydrophobicity and hydrophilicity. The present invention controls the temperature of the carbonization treatment so that the doped nitrogen in the graphene nanofiber membrane is mainly pyrrolic nitrogen and pyridinic nitrogen, so that the nitrogen-doped graphene nanofiber membrane has hydrophilicity, which is beneficial to the realization of chemical 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 treatment time is 1 hour-1.5 hours, and the heating rate is 1.8-2.5°C / mim, which can effectively achieve nitrogen doping while ensuring the hydrophilicity of the graphene nanofiber membrane.

[0042] Furthermore, the protective atmosphere can be selected from an inert gas, and the inert gas can be selected from argon, nitrogen, and the like.

[0043] Since the diameter of the graphene nanofiber membrane obtained by the present invention is small, the requirements for chemical plating are higher. Therefore, in step S4 of the present invention, the hydrophilic nitrogen-doped graphene nanofiber membrane is first sensitized and activated, and then chemically plated.

[0044] Specifically, in step S4, the hydrophilic nitrogen-doped graphene nanofiber membrane is first subjected to sensitization treatment, so that a layer of sensitizer is adsorbed on the surface of the hydrophilic nitrogen-doped graphene nanofiber membrane to ensure that a reduction reaction occurs during activation. Optionally, the hydrophilic nitrogen-doped graphene nanofiber membrane can be placed in a sensitizer solution, or the sensitizer is formed on the hydrophilic nitrogen-doped graphene nanofiber membrane by spraying, etc., so that a layer of sensitizer is adsorbed on the surface of the hydrophilic nitrogen-doped graphene nanofiber membrane. Optionally, the sensitizer is selected from stannous chloride.

[0045] After the sensitization treatment, the hydrophilic nitrogen-doped graphene nanofiber membrane with a sensitizer on the surface is activated. During the activation treatment, the activator is reduced by the sensitizer to generate catalyst particles and adhere to the surface of the hydrophilic nitrogen-doped graphene nanofiber membrane to form a catalytic active layer. In the subsequent chemical plating step, the chemical plating can be carried out spontaneously. Optionally, the hydrophilic nitrogen-doped graphene nanofiber membrane with a sensitizer on the surface can be placed in an activator solution, or the activator can be formed on the hydrophilic nitrogen-doped graphene nanofiber membrane with a sensitizer on the surface by spraying or the like. Optionally, the activator is selected from at least one of palladium chloride and platinum chloride.

[0046] For example, the hydrophilic nitrogen-doped graphene nanofiber membrane is first sensitized with tin chloride to adsorb a layer of stannous chloride on the surface of the hydrophilic nitrogen-doped graphene nanofiber membrane. When palladium chloride is then used for activation treatment, the palladium ions are reduced by the stannous ions adsorbed on the surface of the hydrophilic nitrogen-doped graphene nanofiber membrane to generate palladium element, which is attached to the surface of the hydrophilic nitrogen-doped graphene nanofiber membrane in the form of colloidal particles to form a catalytically active layer. In the subsequent chemical plating step, the palladium element particles in the catalytically active layer can serve as catalytic centers to enable spontaneous chemical plating.

[0047] The chemical plating method provided by the present invention is universal and is suitable for chemically plating a variety of metals on the surface of a graphene nanofiber film material. Optionally, the chemical plating solution is selected from at least one of a chemical copper plating solution, a chemical nickel plating solution, a chemical silver plating solution, a chemical tin plating solution, or a chemical gold plating solution. For example, when the chemical plating solution is a chemical copper plating solution, a copper-graphene nanocomposite fiber film material can be obtained, and when the chemical plating solution is a chemical nickel plating solution, a nickel-graphene nanocomposite fiber film material can be obtained.

[0048] The present invention also provides a metal-graphene nanofiber composite membrane material prepared by the 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 pyrrolic nitrogen in the nitrogen atoms is 40%-60%, and the molar percentage of pyridinic nitrogen is 30%-50%.

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

[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 elements, and the absolute shielding effectiveness can reach 90db·cm in the range of 8.2GHz-12.4GHz. 3 / g.

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

[0052] Hereinafter, the metal-graphene nanofiber membrane composite material and its preparation method and application will be further described through the following specific examples.

[0053] Example 1

[0054] Take 6g of sodium polyacrylate (weight average molecular weight 10 6 ) and 20.0 mg / g of graphene oxide solution (the flake size of graphene oxide is 30 μm) are mixed, and then 0.024 g of surfactant Triton-X100 is added, and the mixture is stirred evenly using a planetary mixer to obtain a dispersion, wherein the mass fraction of graphene oxide in the dispersion is 10%, the mass fraction of sodium polyacrylate in the dispersion is 10%, and the mass fraction of Triton-X100 in the dispersion is 1%.

[0055] The above dispersion was used as the spinning solution. 10 g of the spinning solution was taken with a syringe and placed in the electrospinning machine. A metal needle was connected to the syringe, perpendicular to the collecting roller, and connected to the positive voltage of the spinning machine. The collecting roller was wrapped with a copper mesh so that all the prepared graphene oxide nanofiber membranes were collected on the copper mesh. The chamber temperature of the electrospinning was adjusted to 45 ° C, the humidity was 10%, the extrusion rate was 0.01 ± 0.002 mL / min, the distance between the collecting roller and the metal needle was 20 cm, the spinning machine voltage was 15KV, and a 10 μm thick graphene oxide nanofiber membrane was prepared on the collecting roller after 4 hours.

[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 a graphene nanofiber membrane.

[0057] The graphene nanofiber membrane and urea were placed in a tube furnace at a mass ratio of 1:1, argon gas was introduced, the temperature was increased at a rate of 2°C / min, and 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 2 S / m.

[0058] Depend on Figure 1 It can be seen that the hydrophilic nitrogen-doped graphene nanofiber membrane has obvious fiber shape and relatively smooth surface morphology. Figure 2 As shown, the nitrogen peak distribution pattern of XPS of the hydrophilic nitrogen-doped graphene nanofiber membrane obtained in this embodiment is obvious, mainly pyrrolic nitrogen and pyridinic nitrogen, and the content of graphite nitrogen is relatively small. After testing, the molar percentage of nitrogen atoms in the nitrogen-doped graphene nanofiber membrane is 6.8%, of which the molar percentage of pyrrolic nitrogen is 41%, the molar percentage of pyridine nitrogen is 36%, the molar percentage of graphite nitrogen is 20%, and the molar percentage of adsorbed nitrogen is 3%.

[0059] The hydrophilic nitrogen-doped graphene nanofiber membrane is placed in a 20g / L stannous chloride solution and soaked at 30°C for 10 minutes, and then fully washed; then placed in a 0.5g / L palladium chloride solution and soaked at 30°C for 10 minutes, and then fully washed to complete 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 according to 8 g / L of copper sulfate, 1 g / L of nickel sulfate, 40 g / L of sodium hypophosphite, 20 g / L of citric acid, 30 g / L of boric acid, 100 mg / L of PEG, and 4 mg / L of potassium ferrocyanide, and then the pH was adjusted to 9.5 with sodium hydroxide to obtain a chemical copper plating solution. The hydrophilic nitrogen-doped graphene nanofiber membrane that had completed the sensitization treatment and activation treatment was then placed in the chemical copper plating solution, heated to 65°C for reaction for 10 minutes, and a copper-graphene nanofiber membrane composite material was obtained.

[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. After testing, the density of the copper-graphene nanofiber membrane composite material is 0.448g / cm 3 , only 5% of pure copper, and the conductivity is as high as 3×10 4 S / m.

[0062] Example 2

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

[0064] The nitrogen-doped graphene nanofiber membrane obtained in this embodiment has a molar percentage of nitrogen atoms of 5.8%, wherein the molar percentage of pyrrolic nitrogen is 58%, the molar percentage of pyridinic nitrogen is 39%, the molar percentage of adsorbed nitrogen is 3%, and there is no graphitic nitrogen. The contact angle is 12° and the conductivity is 3.40×10 2 S / m; the density of the obtained copper-graphene nanofiber membrane composite material is 0.45g / cm 3 , the conductivity is as high as 2.83×10 4 S / m.

[0065] Example 3

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

[0067] The nitrogen-doped graphene nanofiber membrane obtained in this embodiment has a molar percentage of nitrogen atoms of 4.7%, wherein the molar percentage of pyrrolic nitrogen is 59%, the molar percentage of pyridinic nitrogen is 38%, the molar percentage of adsorbed nitrogen is 3%, and there is no graphitic nitrogen. The contact angle is 10° and the conductivity is 2.15×10 2 S / m; the density of the obtained copper-graphene nanofiber membrane composite material is 0.45g / cm 3 , the conductivity is as high as 2.78×10 4 S / m.

[0068] Comparative Example 1

[0069] The only difference between Comparative Example 1 and Example 1 is that no urea is added in the carbonization step.

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

[0071] Comparative Example 2

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

[0073] The nitrogen-doped graphene nanofiber membrane obtained in this comparative example has a molar percentage of nitrogen atoms of 5.8%, wherein the molar percentage of pyrrolic nitrogen is 9%, the molar percentage of pyridinic nitrogen is 53%, and the molar percentage of graphitic nitrogen is 38%. There is no adsorbed nitrogen, and its contact angle is 130° and the conductivity is 2.02×10 3 S / m.

[0074] Comparative Example 3

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

[0076] The nitrogen-doped graphene nanofiber membrane obtained in this comparative example has a molar percentage of nitrogen atoms of 4.6%, wherein the molar percentage of pyridinic nitrogen is 36%, the molar percentage of graphitic nitrogen is 64%, and there is no pyrrolic nitrogen and adsorbed nitrogen. The contact angle is 140° and the conductivity is 4.07×10 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 was 75db·cm in the range of 8.2-12.4Ghz. 3 / g; copper-graphene nanofiber membrane composite material is as high as 90db·cm in the range of 8.2-12.4Ghz 3 / g; for the same size, the copper mesh is only 25db·cm in the range of 8.2-12.4Ghz 3 / g.

[0078] Example 4

[0079] The difference between Example 4 and Example 1 is that a solution is prepared according to 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, and the pH is adjusted to 5 with sulfuric acid to obtain a chemical nickel plating solution. The hydrophilic nitrogen-doped graphene nanofiber membrane that has completed the sensitization treatment and activation treatment is then placed in the chemical nickel plating solution, heated to 80° C. for reaction for 10 minutes, and a nickel-graphene nanofiber membrane composite material is obtained.

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

[0081] Example 5

[0082] The difference between Example 5 and Example 1 is that first, a silver salt solution is prepared, specifically 10g / L silver nitrate, 60mL / L ammonia, 20mL / L ethylenediamine, 6g / L potassium hydroxide, 70mg / L sodium thiosulfate pentahydrate, and then a reducing agent solution is prepared, specifically 8g / L glucose, 2.5g / L potassium sodium tartrate, 40mL / L ethanol, 75mg / L PEG1000, and the two solutions are mixed to obtain a chemical silver plating solution. Then the hydrophilic nitrogen-doped graphene nanofiber membrane that has been sensitized and activated is placed in a 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 is 0.237 g / cm 3 , the conductivity is as high as 4.52×10 4 S / m.

[0084] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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 above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a metal-graphene nanofiber membrane composite material, characterized in that: The following steps are involved: Using a dispersion of graphene oxide, polymer and surfactant as a spinning solution, electrospinning is performed to obtain a graphene oxide nanofiber membrane; The graphene oxide nanofiber membrane is subjected to a reduction treatment to obtain a graphene nanofiber membrane; Carrying out a carbonization treatment on the graphene nanofiber membrane and urea under a protective atmosphere to obtain a hydrophilic nitrogen-doped graphene nanofiber membrane, wherein the temperature of the carbonization treatment is 500° C.-700° C.; The hydrophilic nitrogen-doped graphene nanofiber membrane is subjected to sensitization treatment and activation treatment, and then chemically plated in a chemical plating solution to obtain a metal-graphene nanofiber membrane composite material.

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

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 treatment time is 1 hour 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 activating agent 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 chemical plating solution is selected from at least one of a chemical copper plating solution, a chemical nickel plating solution, a chemical silver plating solution, a chemical tin plating solution or a chemical 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 pyrrolic nitrogen in the nitrogen atoms is 40%-60%, and the molar percentage of pyridinic nitrogen is 30%-50%.

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

10. An electromagnetic shielding element prepared using the metal-graphene nanofiber membrane composite material according to claim 8 or 9.

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