CN116239915A

CN116239915A - Copper-doped graphene ink, and preparation method and application thereof

Info

Publication number: CN116239915A
Application number: CN202211694985.3A
Authority: CN
Inventors: 吴炳辉; 孙军旗; 邵志恒; 郑南峰
Original assignee: Xiamen University; Tan Kah Kee Innovation Laboratory
Current assignee: Xiamen University; Tan Kah Kee Innovation Laboratory
Priority date: 2022-12-28
Filing date: 2022-12-28
Publication date: 2023-06-09

Abstract

The invention provides copper-doped graphene ink, which comprises the following components: 5-15 parts of graphene; 0.5 to 5 parts by weight of conductive filler; 12-45 parts of binder; 0.5 to 2 parts by weight of hydrophilic oxide; 25-48 parts by weight of a high boiling point solvent; 5-20 parts of antioxidant micrometer copper. Compared with the prior art, the printing ink provided by the invention can complete conductivity after being solidified, so that the printing ink can be electroplated, the antioxidation micron copper in the printing ink can not only improve conductivity, but also be used as an electroplating active site to improve the adhesive force of a coating, so that the pollution problem of hexavalent chromium in industry is solved, the cost is further reduced, the printing ink is suitable for various functional plastic products needing electroplating, and the adhesive force can meet the requirements.

Description

Copper-doped graphene ink, and preparation method and application thereof

Technical Field

The invention belongs to the technical field of electroplating processes, and particularly relates to copper-doped graphene ink, a preparation method and application thereof.

Background

The surface metal coating technology is a surface engineering technology for decorating and protecting the surface of a substrate and obtaining certain special performances, and is also a metal deposition technology.

The surface metal plating technology can be classified into wet plating and dry plating. Wherein wet plating can be classified into chemical plating, electroplating and hot dip plating. Electroless plating is a method of forming a dense plating layer on the surfaces of various materials by reducing metal ions to metal in a solution containing the metal ions using a strong reducing agent according to the principle of redox reaction without applying electricity. The electroplating process is an electrochemical reduction process that occurs at the interface of the metal and the electrolyte, provided that sufficient contact between the electrolyte and the metal is ensured. The purpose of electroless plating is to create a conductive metal film (typically copper or nickel plated) on the surface of the plastic article, creating conditions for electroplating the plastic article with the metal layer.

In the current industry, in order to obtain a good plating layer with good binding force and different surface textures, the traditional processes of roughening, activating and chemical plating, namely conducting pretreatment and electroplating are still adopted. However, hexavalent chromium used in the roughening process has serious environmental pollution, obvious irreversible damage to first-line workers in direct contact is more obvious, the use of hexavalent chromium is more and more strictly limited in related countries and regions, and the use of noble metal palladium in the activation process and the requirement of meeting related environmental specifications lead to continuous rising of electroplating cost and wastewater treatment cost of electroplating plants, so that a green and environment-friendly production process is needed in the plastic electroplating industry.

At present, the main research directions for developing novel environment-friendly plastic electroplating technology are as follows: (1) The etchant components are adjusted to avoid the use of hexavalent chromium, such as using manganese dioxide to replace chromic acid, increasing the use amount of sulfuric acid to avoid using chromic acid and hydrogen peroxide/nitric acid to replace chromic acid, and the schemes avoid the use of hexavalent chromium, but have poor coarsening effect, low yield and far less final adhesive force than the actual application requirement; (2) Modifying the surface of a substrate, such as grafting P-TES (6-azide-2, 4-bis (3-triethoxysilyl) propylamino-1, 3,5 triazine) on a plastic substrate through UV (ultraviolet irradiation), grafting N-TES (6-azide-2, 4 dithiol monosodium (3-triethoxysilyl) propylamino-1, 3,5 triazine) on the surface of the plastic through self-assembly to form molecular bonding, chemically spraying Ag, adsorbing an Ag film on an organic functional group after the molecular bonding, electroplating again, or hydrolyzing and modifying cyano on the surface of ABS (acrylonitrile-butadiene-styrene copolymer) into carboxyl by using a sodium hydroxide solution, adsorbing silver ions by the carboxyl to replace palladium for activation, completing conductive pretreatment by electroless copper plating, or grafting PAA (polyacrylic acid) on the surface of the plastic, adsorbing copper ions by the PAA, and forming conductive pretreatment after reduction, thereby avoiding the use of hexavalent chromium and noble metal palladium, but having more complicated steps and higher cost and limited adhesive force provided by the surface energy of the substrate; (3) The scheme can avoid the use of hexavalent chromium and noble metal palladium, but the addition of the conductive material can influence the mechanical property of the plastic, the conductivity is also to be improved, and good adhesive force cannot be ensured; (4) The scheme avoids the use of hexavalent chromium and noble metal palladium, has the advantages of simple working procedure, suitability for industrial mass production and the like, but the currently reported difficulties are that the adhesive force can not meet the actual application requirements, and the decorative plastic electroplated workpiece with mirror effect is more difficult to electroplate to obtain good mirror luster.

Disclosure of Invention

In view of the above, the technical problem to be solved by the present invention is to provide a copper-doped graphene ink which has a strong adhesive force and is suitable for electroplating and conductive treatment of decorative plastics requiring a mirror effect, and a preparation method and application thereof.

The invention provides copper-doped graphene ink, which comprises the following components:

preferably, the conductive filler is selected from one or more of carbon black, silver nanoparticles and nickel nanoparticles;

the binder is one or more selected from polyurethane, acrylic resin, phenolic resin and epoxy resin;

the high boiling point solvent has a boiling point greater than 150 ℃.

Preferably, the hydrophilic oxide is selected from hydrophilic silica.

Preferably, the high boiling point solvent is selected from one or more of dimethylformamide, N-methylpyrrolidone and dibasic acid ester.

Preferably, the method comprises the steps of:

the invention also provides a preparation method of the copper-doped graphene ink, which comprises the following steps:

and mixing graphene, conductive filler, binder, hydrophilic oxide, high-boiling point solvent and antioxidant micrometer copper to obtain the copper-doped graphene ink.

The invention also provides application of the copper-doped graphene ink in electroplating pretreatment technology.

The invention also provides an electroplating method, which comprises the following steps:

and coating the copper-doped graphene ink on a substrate, and then electroplating.

Preferably, the thickness of the copper-doped graphene ink coating is 10-200 microns.

Preferably, the electroplating is specifically as follows: and (5) sequentially carrying out cyanide-free pyrophosphate copper plating, bright copper electroplating and semi-bright nickel electroplating.

Drawings

FIG. 1 is a laser microscope test chart for shape measurement of a cured layer of conductive ink prepared in example 1 and comparative example 1 of the present invention;

FIG. 2 is a graph showing the specular gloss effect of the conductive plastic substrate prepared in example 1 of the present invention.

Detailed Description

The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The invention provides copper-doped graphene ink, which comprises the following components: 5-15 parts of graphene; 0.5 to 5 parts by weight of conductive filler; 12-45 parts of binder; 0.5 to 2 parts by weight of hydrophilic oxide; 25-48 parts by weight of a high boiling point solvent; 5-20 parts of antioxidant micrometer copper.

The source of all the raw materials is not particularly limited, and the raw materials are commercially available.

The content of graphene in the copper-doped graphene ink provided by the invention is preferably 5-12 parts by weight, more preferably 6-10 parts by weight.

The copper-doped graphene ink provided by the invention comprises a conductive filler, wherein the conductive filler can be filled between graphene sheets to improve conductivity; the content of the conductive filler in the copper-doped graphene ink is preferably 1-5 parts by weight, more preferably 1-4 parts by weight, and still more preferably 2-3 parts by weight; the kind of the conductive filler is not particularly limited as long as it is a conductive filler well known to those skilled in the art, and one or more of carbon black, silver nanoparticles and nickel nanoparticles are preferable in the present invention.

The content of the binder in the copper-doped graphene ink provided by the invention is preferably 15-45 parts by weight, more preferably 20-40 parts by weight, still more preferably 30-40 parts by weight, and most preferably 35-40 parts by weight; the binder may be any resin known to those skilled in the art as a binder, and is not particularly limited, but one or more of polyurethane, acrylic resin, phenolic resin and epoxy resin are preferable in the present invention, and polyurethane is more preferable; in the present invention, the molecular weight of the polyurethane is preferably 2000 to 10000, more preferably 4000 to 8000, still more preferably 6000 to 7000, most preferably 6500; the tensile strength of the polyurethane is preferably 50 to 100MPa, more preferably 60 to 90MPa, still more preferably 70 to 80MPa.

The hydrophilic oxide is added into the printing ink, so that the hydrophilicity of the printing ink can be improved, the film layer is guaranteed to have good hydrophilicity, the electroplating solution can infiltrate into the film layer, and in the subsequent electroplating, metal ions in the electroplating solution are reduced and then form an alloy with the antioxidant micron copper in the film layer, so that good adhesive force is guaranteed. The content of the hydrophilic oxide in the copper-doped graphene ink is preferably 0.8-1.5 parts by weight, more preferably 1 part by weight; the hydrophilic oxide is preferably hydrophilic silica, more preferably hydrophilic fumed silica; in the examples provided herein, hydrophilic fumed silica A380 is specifically exemplified; the hydrophilic silicon dioxide can ensure that the ink layer formed by the copper-doped graphene ink has certain hydrophilicity, can effectively reduce the change of resistivity caused by resin swelling, and can also improve the mechanical strength of the ink layer.

The copper-doped graphene ink provided by the invention adopts the high-boiling point solvent, the high-boiling point solvent can better dissolve resin, the volatilization is slow, a smooth ink layer can be easily obtained after drying, and a smooth and specular-luster coating can be formed after electroplating on a relatively smooth surface. The content of the high boiling point solvent in the copper-doped graphene ink is preferably 28 to 45 parts by weight, more preferably 30 to 40 parts by weight, and still more preferably 31 to 38 parts by weight; in the present invention, the boiling point of the high boiling point solvent is preferably greater than 150 ℃; the high boiling point solvent is preferably one or more of Dimethylformamide (DMF), N-methylpyrrolidone (NMP) and dibasic acid ester (DBE).

The copper-doped graphene ink provided by the invention contains the antioxidant micro copper, is used for providing electroplating active sites, and can maintain the stability of the ink for a long time by using the micro copper with the antioxidant function. The content of the antioxidant micro copper in the copper-doped graphene ink is preferably 5-15 parts by weight, more preferably 5-10 parts by weight, and still more preferably 5-8 parts by weight; the antioxidant micro copper is a micro copper particle with antioxidant property, which is well known to those skilled in the art, and is not particularly limited, and the antioxidant micro copper prepared according to the method in chinese patent publication No. CN113707362a is preferred in the present invention.

The printing ink provided by the invention can complete conductivity after being solidified, so that the printing ink can be electroplated, the antioxidation micron copper in the printing ink can not only improve conductivity, but also be used as an electroplating active site to improve the adhesive force of a plating layer, so that the pollution problem of hexavalent chromium in industry is solved, the cost problem is further reduced, the printing ink is suitable for various functional plastic products needing electroplating, the adhesive force can meet the requirements, and good specular gloss can be electroplated for decorative plastic electroplating workpieces needing specular effects.

The invention also provides a preparation method of the copper-doped graphene ink, which comprises the following steps: and mixing graphene, conductive filler, binder, hydrophilic oxide, high-boiling point solvent and antioxidant micrometer copper to obtain the copper-doped graphene ink.

The contents and types of the graphene, the conductive filler, the binder, the hydrophilic oxide, the high boiling point solvent and the antioxidant micro copper are the same as those described above, and are not repeated here.

Mixing graphene, conductive filler, binder, hydrophilic oxide, high boiling point solvent and antioxidant micrometer copper; the mixing method is a method well known to those skilled in the art, and is not particularly limited, and ball milling or sand milling is preferable in the present invention; the mixing time is preferably 0.5-3 hours; the rotational speed of the mixing is preferably 200 to 500rpm, more preferably 300 to 400rpm, still more preferably 350rpm; the ball-material ratio of the ball mill or the sand mill is preferably 1 to 1.5, more preferably 1.1; the grinding balls used for ball milling or sanding preferably comprise grinding balls having different diameters, wherein the volume ratio of large balls to small balls is preferably (3 to 6): 1, more preferably (4 to 5): 1, more preferably 5:1, a step of; the diameter of the large sphere is preferably 8-15 mm, more preferably 10mm; the diameter of the pellets is preferably 3 to 6mm, more preferably 5mm.

The invention also provides application of the copper-doped graphene ink in a pre-electroplating treatment technology. The copper-doped graphene ink provided by the invention can be directly electroplated after being solidified into a film, solves the pollution problem of hexavalent chromium in industry, further reduces the cost, and is suitable for decorative products with specular gloss.

The invention also provides an electroplating method, which comprises the following steps: and coating the copper-doped graphene ink on a substrate, and then electroplating.

Coating copper-doped graphene ink on a substrate; the coating method is a method well known to those skilled in the art, and there is no particular limitation in blade coating, spraying, dipping, etc.; the thickness of the coating is preferably 10 to 200 microns (on a dried basis), more preferably 20 to 150 microns, still more preferably 40 to 100 microns, most preferably 60 to 70 microns; the substrate is a substrate well known to those skilled in the art, and is not particularly limited, and is preferably an ABS plastic substrate that is not conductive in the present invention.

After coating, curing to form a film; the method for curing and forming the film is a method well known to the person skilled in the art, and the method of naturally airing, drying and the like is not particularly limited, and the method is preferably drying in the invention; the temperature of the drying is preferably 40-80 ℃, more preferably 50-60 ℃; the drying time is preferably 1 to 3 hours.

Then electroplating is carried out; the electroplating process is a well-known electroplating process for the person skilled in the art, and is not particularly limited, and in the invention, a plating solution with small influence on the environment is preferably selected, specifically, cyanide-free pyrophosphate copper plating is firstly carried out; the plating solution used for the cyanide-free pyrophosphate copper plating preferably includes: 17-18 parts of pyrophosphate, 5.5-6 parts of copper salt, 5-6 parts of buffer salt, 0.6-1 part of ammonia water, 0.1-0.3 part of polyethylene glycol and 70-71 parts of water; the pyrophosphate is preferably potassium pyrophosphate; the copper salt is preferably copper sulfate; the buffer salt is preferably dipotassium hydrogen phosphate; the polyethylene glycol is preferably polyethylene glycol-600; the current density of the cyanide-free pyrophosphate copper plating is preferably 0.5-1 ASD; the time for plating copper by the cyanide-free pyrophosphate is preferably 10-20 min; the binding force between the plating layer and the substrate can be improved by taking the pyrophosphate copper plating as the bottoming plating layer, and the cyanide-free process is further adopted, so that the method is environment-friendly.

After the cyanide-free pyrophosphate is plated with copper, preferably, bright copper is electroplated, so that a plating layer with higher corrosion resistance can be obtained; the plating solution used for plating bright copper is well known to those skilled in the art, and is not particularly limited, and the acid copper plating solution used for plating bright copper in the invention preferably comprises 180-200 g/L of copper sulfate, 62-68 g/L of sulfuric acid and 80-100 ppm of chloride ions; the current density of the electroplated bright copper is preferably 2-6 ASD; the time for electroplating the bright copper is preferably 10-30 min.

After plating the bright copper, preferably, semi-bright nickel is also plated; the plating solution used for plating the semi-gloss nickel preferably comprises 220-240 g/L of nickel sulfate, 60-70 g/L of nickel chloride and 40-50 g/L of boric acid; the current density of the electroplated semi-gloss nickel is preferably 1-2 ASD; the time for plating the semi-gloss nickel is preferably 5-10 min.

In the invention, the electroplating can be continued later according to the product requirement, such as full gloss nickel, microporous nickel, bright chromium and the like.

After the electroplating, drying is preferably also performed; residual moisture in micropores of the ink layer can be removed by drying, so that a plating layer with good adhesive force is obtained; the drying is preferably vacuum drying; the drying temperature is preferably 40-100 ℃, more preferably 60-80 ℃; the drying time is preferably 6 to 24 hours.

Compared with the traditional electroplating process flow, the method for realizing the conductive treatment by coating the copper-doped graphene ink on the non-conductive plastic substrate replaces the conductive pretreatment method of degreasing-roughening-activating-chemical plating in the traditional process, and can avoid the use of hexavalent chromium in the roughening process and noble metal palladium in the activating process. In addition, complex technological processes such as degreasing, neutralization, de-sizing, chemical plating and the like are simplified, the process is environment-friendly, and the cost is greatly reduced.

In order to further illustrate the invention, the following describes in detail the copper-doped graphene ink, the preparation method and the application thereof provided by the invention with reference to examples.

The reagents used in the following examples are all commercially available, and the antioxidant micrometer copper powder used in the examples is C-1 prepared in Chinese patent publication No. CN 113707362A; the hydrophilic silica used in the examples and comparative examples were all A380 hydrophilic fumed silica purchased from Desoxhlet; molecular weight of polyurethane: 6500, tensile strength: 70MPa,100% modulus: 4.5; the graphene is 8 mu m high-purity expanded graphite purchased from Qingdao rock-sea carbon materials limited company; the carbon black is Cabot BLACK PEARLS 2000 superconducting carbon black purchased by Kabot in the United states; the nickel powder is 10 mu m sheet-shaped conductive nickel powder purchased from Shanghai Nameko nano technology Co., ltd; ABS is purchased from the healthy home stock company of Xiamen Jianlin; the common micron copper powder is 1000-mesh high-purity copper powder purchased by Sharp alloy welding materials in Nanguo.

Example 1

Preparing copper-doped graphene ink: 10 parts of graphene, 8 parts of antioxidant micrometer copper powder, 3 parts of carbon black, 1 part of hydrophilic silicon dioxide, 40 parts of polyurethane and 38 parts of DMF (dimethyl formamide), and ball milling for 3 hours at 350rpm by using a planetary ball mill (ball with a diameter of 10mm and ball with a diameter of 5mm are adopted for mixed ball milling (ball: ball=5:1), and the ball-to-material ratio (by volume) =1.1) is used for obtaining the copper-doped graphene ink.

Preparation of a conductive ink curing layer: and transferring the copper-doped graphene ink onto a non-conductive plastic substrate (ABS) by using a spraying method, and drying at 60 ℃ for 2 hours to solidify the slurry into a film.

Preparation of a conductive plastic substrate: the cyanide-free alkaline pyrophosphate copper plating solution was used in sequence at 1A/dm ² Electroplating for 10min, and the bright acid copper plating solution is used for 6A/dm ² Electroplating for 30min, wherein the semi-gloss nickel plating solution is 2A/dm ² Electroplating for 5min. The plating solution compositions used are shown in tables 1 to 3.

TABLE 1 copper pyrophosphate bath composition table

TABLE 2 Bright acid copper plating bath composition Table

TABLE 3 semi-gloss Nickel plating solution composition Table

Post-treatment parameters: and drying for 24 hours at 60 ℃ under vacuum.

Comparative example 1

Preparing conductive ink: 10 parts of graphene, 8 parts of common micrometer copper powder, 3 parts of carbon black, 1 part of hydrophilic silicon dioxide, 40 parts of polyurethane and 38 parts of DMF.

The preparation of the cured layer of conductive ink and the preparation of the conductive plastic substrate were the same as in example 1.

Comparative example 2

Preparing conductive ink: 10 parts of graphene, 8 parts of nickel powder, 3 parts of carbon black, 1 part of hydrophilic silicon dioxide, 40 parts of polyurethane and 38 parts of DMF.

Comparative example 3

Preparing conductive ink: 10 parts of graphene, 8 parts of antioxidant copper powder, 3 parts of carbon black, 1 part of hydrophilic silicon dioxide, 40 parts of polyurethane and 38 parts of NMP.

Comparative example 4

The conductive pretreatment is a traditional etching-activating-electroless plating process, and the electroplating conditions are the same as those of the embodiment 1, and specifically the following steps are adopted: (1) alkaline degreasing: naOH 50g/L, na ₃ PO ₄ ：30g/L，Na ₂ CO ₃ :15g/L, temperature: 40-45 ℃ for the time of: 5min; (2) swelling: acetone: water=1:2 (volume ratio), temperature: room temperature, time: 15min; (3) coarsening: crO (CrO) ₃ ：400g/L，H ₂ SO ₄ :350g/L, temperature: 50-75 ℃ for the time of: 60min; (4) alkaline washing 10% (mass fraction) NaOH solution, temperature: room temperature, time: 5min; (5) sensitization: snCl ₂ ·2H ₂ O:15g/L, HCl:45ml/L, temperature: room temperature, time: 5min; (6) Activation of PbCl ₂ :0.5g/L; HCl:10ml/L, temperature: room temperature, time: 1-3 min; (7) electroless copper plating: cuSO ₄ ·5H ₂ O:15g/L, p-toluenesulfonic acid amine: 20-22 g/L, potassium sodium tartrate: 60g/L, formaldehyde: 0.06-0.15 g/L, nickel chloride: 2g/L, naOH: 10-15 g/L, formaldehyde: 8-18 g/L, temperature: 25 ℃ for the time of: 20min.

Performance detection

1. Conductive ink performance test

The conductive inks prepared in example 1 and comparative examples 1 to 3 were respectively subjected to resistivity test and sheet resistance test, and the results are shown in table 4. As can be seen from Table 4, the plated conductive ink layer prepared in example 1 has lower sheet resistance and resistivity and better conductivity than those of comparative examples 1 to 3.

TABLE 4 resistivity/sheet resistance test results for conductive inks prepared in example 1 and comparative examples 1-3

2. Conductive ink cured layer performance test

The cured conductive ink layers prepared in example 1 and comparative example 4 were subjected to shape measurement laser microscopy to obtain surface roughness, and a surface topography is shown in fig. 1. The cured conductive ink layer prepared in example 1 had a measured surface roughness Sa of 4.9063 μm and the cured conductive ink layer prepared in comparative example 4 had a measured surface roughness Sa of 5.4680 μm, and it can be seen from fig. 1 that the cured conductive ink layer prepared in example 1 was relatively flat and similar to the surface morphology of the ink layer prepared in comparative example 4 using the conventional etching-activation-electroless plating process.

The cured layers of the conductive inks prepared in example 1 and comparative examples 1 to 3 were subjected to a sheet resistance test and a hundred grid test (ASTM D3359 standard test method), respectively, and the results are shown in table 5.

TABLE 5 results of Performance test of cured layers of conductive inks prepared in example 1 and comparative examples 1 to 3

As can be seen from table 5, the cured layers of the conductive ink prepared in example 1 and comparative examples 1 to 3 were comparable in the hundred-cell test result level, and the cured layers of the conductive ink prepared in example 1 satisfied the requirements of commercial applications. Compared with comparative examples 1 to 3, the cured layer of the conductive ink prepared in example 1 has lower sheet resistance and better conductivity.

3. Conductive plastic substrate performance test

The conductive plastic substrates prepared in example 1 and comparative examples 1 to 3 were respectively subjected to a hundred test (ASTM D3359 standard test method and 90 ° tensile test (ASTM B533-85 (2013) standard test method), and the results are shown in table 6.

TABLE 6 results of Performance test of conductive plastic substrates prepared in example 1 and comparative examples 1 to 3

As can be seen from table 6, the conductive plastic substrates prepared in example 1 and comparative examples 1 to 3 are equivalent in the level of the hundred-grid test result, and the tensile test result of the conductive plastic substrate prepared in example 1 at 90 ° is significantly better than that of comparative examples 1 to 3, which indicates that the antioxidant copper particles added in the conductive ink can play a role of electroplating active sites, provide nucleation sites for subsequent electroplated copper, and form metal bonds between newly deposited copper and copper in the original ink, so that the film adhesion is significantly improved, and the conductive plastic substrate can be applied to more severe use environments. Meanwhile, the conductive plastic substrate prepared in the embodiment 1 has higher brightness, and can be suitable for decorative products needing specular gloss, and the specular effect is shown in fig. 2.

Claims

1. The copper-doped graphene ink is characterized by comprising the following components:

2. the copper-doped graphene ink according to claim 1, wherein the conductive filler is selected from one or more of carbon black, silver nanoparticles, and nickel nanoparticles;

the high boiling point solvent has a boiling point greater than 150 ℃.

3. The copper-doped graphene ink of claim 1, wherein the hydrophilic oxide is selected from hydrophilic silica.

4. The copper-doped graphene ink according to claim 1, wherein the high boiling point solvent is selected from one or more of dimethylformamide, N-methylpyrrolidone, and dibasic acid ester.

5. The copper-doped graphene ink according to claim 1, comprising:

6. a method for preparing the copper-doped graphene ink according to claim 1, comprising the steps of:

7. Use of the copper-doped graphene ink according to any one of claims 1 to 5 in a pre-electroplating treatment technique.

8. A plating method, comprising:

a copper-doped graphene ink according to any one of claims 1 to 5 is coated on a substrate and then electroplated.

9. The electroplating method according to claim 8, wherein the copper-doped graphene ink is coated to a thickness of 10-200 microns.

10. The plating method according to claim 8, wherein the plating is specifically: and (5) sequentially carrying out cyanide-free pyrophosphate copper plating, bright copper electroplating and semi-bright nickel electroplating.