阅读说明：本技术 一种氮掺杂石墨烯@金属材料的制备方法在金属防腐领域的应用 (Application of preparation method of nitrogen-doped graphene @ metal material in metal corrosion prevention field ) 是由 马宇飞 吴琼 于 2021-08-16 设计创作，主要内容包括：本发明提供了一种氮掺杂石墨烯@金属材料的制备方法在金属防腐领域的应用,所述氮掺杂石墨烯@金属材料的制备过程包括如下步骤：放置原料步骤、设定反应条件步骤、生长步骤和后处理步骤。本发明用小分子生长大面积少层氮掺杂石墨烯的氮掺杂石墨烯@金属材料制备方法通过芳香族小分子化合物提供碳源和氮源,在金属衬底上生长大面积少层氮掺杂石墨烯,生长温度为300～500℃,该温度下金属衬底的性能得以完好保全,制备的氮掺杂石墨烯以单层居多,氮掺杂石墨烯质量较高,制备的氮掺杂石墨烯@金属材料的防腐性能明显优于原始的金属材料,使用寿命延长。(The invention provides an application of a preparation method of a nitrogen-doped graphene @ metal material in the field of metal corrosion prevention, wherein the preparation process of the nitrogen-doped graphene @ metal material comprises the following steps: the method comprises the steps of raw material placing, reaction condition setting, growth and post-treatment. According to the preparation method of the nitrogen-doped graphene @ metal material with the micromolecule growing large-area few-layer nitrogen-doped graphene, the carbon source and the nitrogen source are provided through the aromatic micromolecule compound, the large-area few-layer nitrogen-doped graphene grows on the metal substrate, the growth temperature is 300-500 ℃, the performance of the metal substrate is well maintained at the temperature, the prepared nitrogen-doped graphene is more in a single layer, the quality of the nitrogen-doped graphene is higher, the corrosion resistance of the prepared nitrogen-doped graphene @ metal material is obviously superior to that of the original metal material, and the service life is prolonged.)

1. The application of the preparation method of the nitrogen-doped graphene @ metal material in the field of metal corrosion prevention is characterized in that the preparation process of the nitrogen-doped graphene @ metal material comprises the following steps:

placing raw materials: providing an accommodating cavity and a growth cavity, wherein the accommodating cavity is communicated with the growth cavity, a metal growth substrate is placed in the growth cavity, and a growth raw material is placed in the accommodating cavity;

setting reaction conditions: vacuumizing the accommodating cavity and the growth cavity until the background vacuum is below 10Pa, then introducing protective gas into the accommodating cavity, introducing the protective gas into the accommodating cavity and discharging the protective gas from the growth cavity, setting the flow of the protective gas to be 50-400 sccm, and maintaining the internal air pressure of the accommodating cavity and the growth cavity to be 20-200 Pa;

growing: adjusting the temperature in the growth cavity to 300-500 ℃, then adjusting the temperature in the accommodating cavity to 20-50 ℃, and the growth time is 10-200 min;

and (3) post-treatment: after the growth is finished, continuously introducing protective gas until the temperature in the growth cavity is reduced to room temperature, and taking out the metal growth substrate when the pressure in the growth cavity is balanced with the external pressure to prepare the nitrogen-doped graphene @ metal material;

the growth raw material is an aromatic micromolecule compound, and a benzene ring of the aromatic micromolecule compound is covalently connected with at least one nitrogen atom.

2. The use of claim 1, wherein the aromatic small molecule compound has a benzene ring covalently linked to at least one amino group.

3. The use of claim 2, wherein the aromatic small molecule compound is one of aniline, an aniline derivative, phenylenediamine, and a phenylenediamine derivative.

4. The application of claim 1, wherein the nitrogen-doped graphene @ metal material comprises a metal growth substrate and nitrogen-doped graphene grown on the metal growth substrate, and the number of layers of the nitrogen-doped graphene is 1-10.

5. The use of claim 4, wherein the nitrogen-doped graphene contains 1% to 25% nitrogen.

6. The use according to claim 4, wherein the metal growth substrate is a copper growth substrate, an aluminum growth substrate, a steel growth substrate, a nickel growth substrate, a silver growth substrate, a platinum growth substrate, and an alloy growth substrate of at least two of copper, aluminum, steel, nickel, silver, platinum.

Technical Field

The invention relates to the technical field of new materials, in particular to application of a preparation method of a nitrogen-doped graphene @ metal material in the field of metal corrosion prevention.

Background

Corrosion of metals is a phenomenon of deterioration or destruction caused by chemical or electrochemical interaction between the metal and the surrounding environment. Metal corrosion causes serious harm to national economy and social life. The corrosion of the material causes the damage of metal equipment and engineering structures, and the metal equipment and the engineering structures leave service in advance, and the economic loss of the material is much higher than the cost of the material. The direct economic loss due to metal corrosion accounts for about 4.2% of the total national production per year, and the metal material scrapped due to corrosion accounts for about 1/10% of the metal production per year worldwide.

The traditional technologies for metal surface treatment mainly comprise chromate treatment and phosphate treatment, and have the disadvantages of high toxicity, serious pollution and great harm to human bodies and the environment. At present, the corrosion science field at home and abroad seeks an environment-friendly and environment-friendly replacement technology for chromate passivation, and organic coatings prepared by organic polymers with a plurality of hydroxyl groups are favored by researchers. However, the organic polymer surface treatment technology also has the defects of large pollution, easy falling and the like in the preparation process, and most importantly, the coating obtained by the organic polymer surface treatment technology through a coating technology is relatively thick (more than 0.5 mm), so that the organic polymer surface treatment technology is not suitable for the anticorrosion treatment of the ultrathin metal sheet.

Graphene is a two-dimensional nanomaterial with a hexagonal honeycomb lattice structure formed by carbon atoms through sp2 hybrid orbitals and only one layer of carbon atoms thick. The unique structure of graphene gives it a number of excellent properties, such as a high theoretical specific surface area (2630 m)²G) and ultrahigh electron mobility (200000 cm)²/v.s), high thermal conductivity (5000W/m.K), high Young's modulus (1.0TPa), and high light transmittance (97.7%), among others. By virtue of the advantages of the structure and the performance of the graphene, the graphene has a huge application prospect in the fields of energy storage and conversion devices, nano-electronic devices, multifunctional sensors, flexible wearable electronics, electromagnetic shielding and the like. It has been proved that the graphene-coated metal material (graphene @ metal alloy) has better conductive and heat dissipation capabilities.

The traditional preparation method of the graphene @ metal alloy material comprises the following steps: the chemical vapor deposition method is a method for synthesizing a new material by utilizing gas molecules to react on the surface of a substrate, and in industry and scientific research, the preparation method of the graphene @ metal alloy generally adopts the chemical vapor deposition method, and gases such as methane, hydrogen and the like are utilized to prepare graphene on a metal substrate at about 1100 ℃. The graphene prepared by the method has more single layers and higher graphene quality, but the method has higher requirements on copper-based materials, high selectivity on the copper-based materials, high energy consumption, lower safety and high cost for preparing the graphene @ metal alloy material, and in addition, the basic performance of the metal can be changed under the high-temperature growth condition, so that the application of the metal in other fields is influenced. The inventor further develops a new application of the graphene @ metal alloy material on the basis of a patent technology (named as: a method for growing large-area few-layer nitrogen-doped graphene by using small molecules, application number is 202010731926.3) developed earlier by the team.

Disclosure of Invention

In view of the above, the invention provides an application of a preparation method of a nitrogen-doped graphene @ metal material in the field of metal corrosion prevention, so as to solve the problems of high pollution, high toxicity, large thickness of a corrosion prevention coating and the like in the existing metal corrosion prevention technology, prevent the metal corrosion from perfectly covering corners, steps and other positions of a device, and prevent the metal corrosion from being truly realized.

The invention provides an application of a preparation method of a nitrogen-doped graphene @ metal material in the field of metal corrosion prevention, wherein the preparation process of the nitrogen-doped graphene @ metal material comprises the following steps:

placing raw materials: providing an accommodating cavity and a growth cavity, wherein the accommodating cavity is communicated with the growth cavity, a metal growth substrate is placed in the growth cavity, and a growth raw material is placed in the accommodating cavity;

setting reaction conditions: vacuumizing the accommodating cavity and the growth cavity to below 10Pa, then introducing protective gas into the accommodating cavity, introducing the protective gas into the accommodating cavity and discharging the protective gas from the growth cavity, setting the flow of the protective gas to be 50-400 sccm, and maintaining the internal air pressure of the accommodating cavity and the growth cavity to be 20-200 Pa;

growing: adjusting the temperature in the growth cavity to 300-500 ℃, then adjusting the temperature in the accommodating cavity to 20-50 ℃, and the growth time is 10-200 min;

and (3) post-treatment: after the growth is finished, continuously introducing protective gas until the temperature in the growth cavity is reduced to room temperature, and taking out the metal growth substrate when the pressure in the growth cavity is balanced with the external pressure to prepare the nitrogen-doped graphene @ metal material;

the growth raw material is an aromatic micromolecule compound, and a benzene ring of the aromatic micromolecule compound is covalently connected with at least one nitrogen atom.

According to the preparation method of the nitrogen-doped graphene @ metal material, the carbon source and the nitrogen source are provided through the aromatic micromolecule compound, the large-area few-layer nitrogen-doped graphene grows on the metal substrate, the growth temperature is 300-500 ℃, the performance of the metal substrate is well maintained at the temperature, the prepared nitrogen-doped graphene is abundant in a single layer, the quality of the nitrogen-doped graphene is high, and the coverage is more comprehensive. Compared with the traditional chemical vapor deposition method, the method utilizes the low-temperature chemical vapor deposition method, takes the organic micromolecules as the raw materials, successfully prepares the single-layer and few-layer nitrogen-doped graphene film on the surfaces of metals such as copper, aluminum, steel, nickel, silver, platinum and the like, and has the advantages of safety, energy conservation, low cost and the like. The greatest innovation point of the invention is as follows: 1. the prepared nitrogen-doped graphene anticorrosive coating is directly grown on the surface of a metal to be protected; 2. the thickness of the nitrogen-doped graphene coating is controllable from several nanometers to dozens of nanometers, the thickness does not affect the thickness of a thin metal foil, the total thickness of an electronic device cannot be increased, meanwhile, for some electronic devices which must use a metal vapor deposition layer with a nanometer scale, an extremely thin metal layer is easier to oxidize in the air, the nitrogen-doped graphene in the item is grown on the surface of the metal layer in situ, and the purpose of protecting the metal thin layer which is easy to oxidize can be achieved on the premise that the size of the electronic device is not increased perfectly; 3. the nitrogen-doped graphene in the project can uniformly grow on any metal device with a complex appearance, and has no corner or step dead angle (dead angles exist when other anticorrosion sizing agents and traditional graphene anticorrosion sizing agents are coated on irregular surfaces such as triangles, steps and grooves). The prepared nitrogen-doped graphene @ metal material has corrosion resistance obviously superior to that of the original metal material, and the real parts of impedance are 351.8 Komega cm²Above, the service life is prolonged. Direct generation of nitrogen-doped grapheneThe adhesive is longer than the metal material, does not need extra adhesive, has better attaching effect, effectively covers the surface microstructure of the metal substrate and prevents the metal surface from being exposed.

Preferably, the benzene ring of the aromatic small molecule compound is covalently linked to at least one amino group. The covalent connection of N and a benzene ring can effectively promote N doping and benzene ring carbon rearrangement to generate graphene.

Preferably, the aromatic small molecule compound is one of aniline, an aniline derivative, phenylenediamine and a phenylenediamine derivative. The aniline, the aniline derivative, the phenylenediamine and the phenylenediamine derivative have good volatility, and can promote benzene ring breakage and carbon structure rearrangement into nitrogen-doped graphene at a low growth temperature.

Preferably, the nitrogen-doped graphene @ metal material comprises a metal growth substrate and nitrogen-doped graphene growing on the metal growth substrate, wherein the number of layers of the nitrogen-doped graphene is 1-10. The nitrogen-doped graphene @ metal material comprises a metal growth substrate and nitrogen-doped graphene growing on the metal growth substrate, the nitrogen-doped graphene directly grows on a metal base material and is fully contacted and covered with the metal base material without an additional bonding material, and the nitrogen-doped graphene @ metal material is integrally formed, so that the exposure of the metal growth substrate is effectively prevented, the corrosion resistance of the metal growth substrate is improved, the preparation cost of the nitrogen-doped graphene @ metal material is also reduced, and the application is more convenient. Compared with the metal material and the metal material covered by the traditional graphene anticorrosive material, the nitrogen-doped graphene @ metal material has a great improvement in the anticorrosive performance, and the modified graphene can greatly improve the anticorrosive performance of the metal material. The anticorrosion principle of the nitrogen-doped graphene @ metal material is based on physical shielding: the nitrogen-doped graphene grows on the metal sheet, the nitrogen-doped graphene has high stability, and meanwhile, the growing nitrogen-doped graphene can densely cover the surface of metal without macroscopic defects, so that the metal sheet is effectively covered to prevent the metal sheet from being exposed in air, water or other chemical environments, and an isolation protection effect is achieved.

Preferably, the nitrogen content of the nitrogen-doped graphene is 1-25%. The metal sheets with different corrosion resistance can be obtained by selecting the nitrogen-doped graphene @ metal materials with different nitrogen doping amounts, the heat dissipation performance and the electric conductivity are different, and the industrial selection of various corrosion-resistant metal materials is met.

Preferably, the metal growth substrate is a copper growth substrate, an aluminum growth substrate, a steel growth substrate, a nickel growth substrate, a silver growth substrate, a platinum growth substrate, and an alloy growth substrate composed of at least two of copper, aluminum, steel, nickel, silver, and platinum. Different corrosion-resistant metal sheets are prepared by selecting different metal growth substrates, and the requirements of the industry on various aspects such as metal toughness, flexibility, heat conduction, electric conductivity, chemical stability and the like are met. The traditional graphene anticorrosive paint is used for coating metal devices with complex shapes, and due to the complex structure of the devices, the method cannot perfectly cover the corners, steps and other positions of the devices, and cannot realize true anticorrosion. In view of this problem, a single-layer or few-layer graphene grown in situ by a chemical method can protect various metal foils represented by copper or complex devices from corrosion. On the premise of keeping the intrinsic property of the metal material, the thin-layer nitrogen-doped graphene grows on the metal with any thickness, any purity and any shape at extremely low cost, and the functions of corrosion prevention and oxidation resistance on the metal material are effectively realized.

More preferably, the metal growth substrate is an ultrathin metal sheet, and the thickness of the ultrathin metal sheet is not affected by the nitrogen-doped graphene anticorrosive layer prepared by the method.

Advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of embodiments of the invention.

Drawings

In order to more clearly illustrate the contents of the present invention, a detailed description thereof will be given below with reference to the accompanying drawings and specific embodiments.

Fig. 1 shows the comparison result of corrosion resistance of the nitrogen-doped graphene @ copper foil and a pure copper sheet.

Detailed Description

While the following is a description of the preferred embodiments of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

The invention provides an application of a preparation method of a nitrogen-doped graphene @ metal material in the field of metal corrosion prevention, wherein the preparation process of the nitrogen-doped graphene @ metal material comprises the following steps:

placing raw materials: providing an accommodating cavity and a growth cavity, wherein the accommodating cavity is communicated with the growth cavity, a metal growth substrate is placed in the growth cavity, and a growth raw material is placed in the accommodating cavity;

setting reaction conditions: vacuumizing the accommodating cavity and the growth cavity to below 10Pa, then introducing protective gas into the accommodating cavity, introducing the protective gas into the accommodating cavity and discharging the protective gas from the growth cavity, setting the flow of the protective gas to be 50-400 sccm, and maintaining the internal air pressure of the accommodating cavity and the growth cavity to be 20-200 Pa;

growing: adjusting the temperature in the growth cavity to 300-500 ℃, then adjusting the temperature in the accommodating cavity to 20-50 ℃, and the growth time is 10-200 min;

and (3) post-treatment: after the growth is finished, continuously introducing protective gas until the temperature in the growth cavity is reduced to room temperature, and taking out the metal growth substrate when the pressure in the growth cavity is balanced with the external pressure to prepare the nitrogen-doped graphene @ metal material;

the growth raw material is an aromatic micromolecule compound, and a benzene ring of the aromatic micromolecule compound is covalently connected with at least one nitrogen atom.

In a specific embodiment, the metal growth substrate is wide in range, comprises various metal foils with unlimited thickness, is a vapor deposited metal coating as thin as a few nanometers to a metal foil with the thickness of a few micrometers, and is a metal device with the thickness of various sizes and shapes, and the size limit of the metal device depends on the size of a growth chamber.

In a specific embodiment, the benzene ring of the aromatic small molecule compound is covalently linked to at least one amino group. The covalent connection of N and a benzene ring can effectively promote N doping and benzene ring carbon rearrangement to generate graphene.

In a specific embodiment, the aromatic small molecule compound is one of aniline, an aniline derivative, phenylenediamine and a phenylenediamine derivative. Most preferably, the aromatic small molecule compound is phenylenediamine, such as o-phenylenediamine, m-phenylenediamine or p-phenylenediamine, or a mixture of at least two of the three.

In a specific embodiment, the metal substrate is a copper growth substrate, an aluminum growth substrate, a steel growth substrate, a nickel growth substrate, a silver growth substrate, a platinum growth substrate, and an alloy growth substrate composed of at least two of copper, aluminum, steel, nickel, silver, and platinum.

In a specific embodiment, in the step of setting the reaction condition, both the accommodating chamber and the growth chamber are vacuumized until the background vacuum degree reaches below 10Pa, such as 8Pa, 5Pa, 3Pa, 1Pa, and then the accommodating chamber is accessed with a protective gas, the protective gas is introduced from the accommodating chamber and exhausted from the growth chamber, and the flow rate of the protective gas is set to be 100-200 sccm, such as 100sccm, 120sccm, 150sccm, 160 sccm, 180sccm, 200 sccm. The pressure inside the accommodating chamber and the growth chamber is maintained to be 50-80 Pa, for example, 50Pa, 60Pa, 70Pa, 80Pa, and the pressure can be changed according to the flow of the introduced gas. Wherein the protective gas is preferably an inert gas: nitrogen, argon, and the like. Most preferably, in the step of setting reaction conditions, the selected protective gas is argon.

In a specific embodiment, after the accommodating cavity and the growth cavity are both vacuumized to below 10Pa, introducing protective gas-argon, cleaning the cavity, then turning off the protective gas, vacuumizing again, and repeating for more than one time, so that the air pressure in the growth cavity is less than 10 Pa.

In a specific embodiment, in the growing step, the temperature in the growth chamber is adjusted to 300-500 ℃, and may be, for example: 300 deg.C, 350 deg.C, 380 deg.C, 400 deg.C, 420 deg.C, 450 deg.C, 480 deg.C, 500 deg.C. Then, the temperature in the accommodating cavity is adjusted to 35-50 ℃, for example: the temperature of the accommodating cavity can be properly adjusted according to the actual reaction conditions based on the volatilization conditions of different aromatic small molecular compounds at 35 ℃, 40 ℃, 45 ℃, 49 ℃ and 50 ℃. The growth time is 30-60 min, and for example, the growth time can be as follows: 30min, 40min, 50min, 60min, or longer time.

In a more specific embodiment, in the growth step, the temperature in the growth chamber is adjusted to 370 ℃, and then the temperature in the accommodating chamber is adjusted to 37 ℃, and the growth time is 60 min.

In a specific embodiment, in the post-processing step, after the temperature in the growth chamber is reduced to room temperature, the growth chamber is cleaned by argon gas for 1, 2 and 3 times, so that the growth chamber is filled with argon gas.

In a specific embodiment, the nitrogen-doped graphene @ metal material comprises a metal growth substrate and nitrogen-doped graphene growing on the metal growth substrate, wherein the number of layers of the nitrogen-doped graphene is 1-10. More preferably, the number of the nitrogen-doped graphene layers is 1-5.

In a specific embodiment, the nitrogen content of the nitrogen-doped graphene is 1% to 25%. Specifically, the nitrogen content may be 1%, 2%, 5%, 10%, 15%, 20%, or 25% due to the difference in growth temperature.

The following describes in detail the preparation method of the nitrogen-doped graphene @ metal material and the prepared nitrogen-doped graphene @ metal material by specific examples.

Example 1

Step A: the growth substrate polycrystalline copper foil with the thickness of 25 mu m is placed in a growth cavity of a CVD tube furnace, growth raw material aniline is placed at the upwind position of the growth cavity, the growth cavity is connected into a vacuum system, and the upwind direction is connected with a protective gas source (argon) and the downwind direction is connected with a vacuum pump.

And B: and vacuumizing the growth system until the air pressure reaches below 8Pa, setting the growth temperature at 400 ℃, wherein most of the metal substrates have certain catalytic reduction capacity. And the C-N bond of the aniline molecule can be maintained below 500 ℃, so that the growth of the nitrogen-doped graphene is facilitated. Setting the flow of argon gas to be 200sccm, maintaining the internal air pressure of the growth cavity to be 70Pa, and enabling molecules of the raw material to have relatively free movement capability under relatively low pressure, so that the molecular rearrangement is facilitated to form the nitrogen-doped graphene.

And C: the temperature of the raw material aniline for growth is maintained at 48 ℃ so as to ensure that the raw material does not excessively volatilize, and simultaneously, the sufficient supply of the raw material for growth can be ensured, and each raw material molecule can be utilized to the maximum extent. The growth time was 60 minutes.

Step D: after the growth is finished, the temperature of the growth cavity is reduced to room temperature, the growth cavity is cleaned by argon gas for three times, the vacuum pump is turned off, the growth cavity is filled with argon gas, the cavity is opened after the air pressure in the cavity is close to atmospheric pressure, the growth substrate is taken out, and the metal material with the large area and the small layer of nitrogen-doped graphene paved on the surface is obtained, namely the nitrogen-doped graphene @ copper material, and the nitrogen content is about 10%.

Example 2

Step A: the growth substrate single crystal copper with the thickness of 0.5mm is placed in a growth cavity of a CVD tube furnace, growth raw material methylaniline is placed in the upwind position of the growth cavity, the growth cavity is connected into a vacuum system, and the upwind direction is connected with a protective gas source (argon) and the downwind direction is connected with a vacuum pump.

And B: and vacuumizing the growth system until the air pressure reaches below 8Pa, and setting the growth temperature at 350 ℃, wherein most of the metal substrates have certain catalytic reduction capacity. And the C-N bond of the methylaniline molecules can be maintained below 500 ℃, so that the growth of the nitrogen-doped graphene is facilitated. Setting the argon flow to be 300sccm, maintaining the internal air pressure of the growth cavity to be 100Pa, and enabling molecules of the raw material to have relatively free movement capability under relatively low pressure, so that the molecular rearrangement is facilitated to form the nitrogen-doped graphene.

And C: the temperature of the growth raw material methylaniline is maintained at 40 ℃ to ensure that the raw material is not excessively volatilized, simultaneously, the sufficient supply of the growth raw material can be ensured, and each raw material molecule can be utilized to the maximum extent. The growth time was 80 minutes.

Step D: after the growth is finished, the temperature of the growth cavity is reduced to room temperature, the growth cavity is cleaned by argon gas for three times, the vacuum pump is turned off, the growth cavity is filled with argon gas, the cavity is opened after the air pressure in the cavity is close to atmospheric pressure, the growth substrate is taken out, and the metal material with the large area and the small layer of nitrogen-doped graphene paved on the surface is obtained, namely the nitrogen-doped graphene @ copper material, and the nitrogen content is about 25%.

Example 3

Step A: the growth substrate purple copper foil with the thickness of 100 mu m is placed in a growth cavity of a CVD tubular furnace, the growth raw material phenylenediamine is placed at the upwind position of the growth cavity, the growth cavity is connected into a vacuum system, and the upwind direction is connected with a protective gas source (argon) and the downwind direction is connected with a vacuum pump.

And B: and vacuumizing the growth system until the air pressure reaches below 8Pa, and setting the growth temperature at 450 ℃, wherein most of the metal substrates have certain catalytic reduction capacity. And the C-N bond of the phenylenediamine molecule can be maintained below 500 ℃, so that the growth of the nitrogen-doped graphene is facilitated. Setting the flow of argon gas to be 400sccm, maintaining the internal air pressure of the growth cavity to be 200Pa, and enabling molecules of the raw material to have relatively free movement capability under relatively low pressure, so that the molecular rearrangement is facilitated to form the nitrogen-doped graphene.

And C: the temperature of the growth raw material methylaniline is maintained at 50 ℃ to ensure that the raw material is not excessively volatilized, simultaneously, the sufficient supply of the growth raw material can be ensured, and each raw material molecule can be utilized to the maximum extent. The growth time was 10 minutes.

Step D: after the growth is finished, the temperature of the growth cavity is reduced to room temperature, the growth cavity is cleaned by argon gas for three times, the vacuum pump is turned off, the growth cavity is filled with argon gas, the cavity is opened after the air pressure in the cavity is close to atmospheric pressure, the growth substrate is taken out, and the metal material with the large area and the small layer of nitrogen-doped graphene paved on the surface is obtained, namely the nitrogen-doped graphene @ copper material, and the nitrogen content is about 15%.

Example 4

Step A: 1.5cm by 0.5cm copper radiating fins are arranged in a growth cavity of the CVD tubular furnace, a growth raw material phenylenediamine is arranged at the upwind position of the growth cavity, the growth cavity is connected into a vacuum system, the upwind position is connected with a protective gas source (argon), and the downwind position is connected with a vacuum pump.

And B: and vacuumizing the growth system until the air pressure reaches below 8Pa, setting the growth temperature at 500 ℃, wherein most of the metal substrates have certain catalytic reduction capacity at the temperature. And the C-N bond of the phenylenediamine molecule can be maintained below 500 ℃, so that the growth of the nitrogen-doped graphene is facilitated. Setting the argon flow to be 200-400 sccm, maintaining the internal air pressure of the growth cavity to be 80-200Pa, wherein the molecules of the raw material have relatively free mobility under relatively low pressure, thereby facilitating the rearrangement of the molecules to form the nitrogen-doped graphene.

And C: the temperature of the growth raw material phenylenediamine is maintained at 25 ℃ to ensure that the raw material is not excessively volatilized, simultaneously, the sufficient supply of the growth raw material can be ensured, and each raw material molecule can be utilized to the maximum extent. The growth time was 100 minutes.

Step D: after the growth is finished, the temperature of the growth cavity is reduced to room temperature, the growth cavity is cleaned by argon gas for three times, the vacuum pump is turned off, the growth cavity is filled with argon gas, the cavity is opened after the air pressure in the cavity is close to atmospheric pressure, the growth substrate is taken out, and the metal material with the large area and the small layer of nitrogen-doped graphene paved on the surface is obtained, namely the nitrogen-doped graphene @ copper material, and the nitrogen content is about 10%.

Example 5

Step A: the growth substrate silver foil with the thickness of 100 mu m is placed in a growth cavity of a CVD tubular furnace, the growth raw material phenylenediamine is placed in the upwind position of the growth cavity, the growth cavity is connected into a vacuum system, and the upwind direction is connected with a protective gas source (nitrogen) and the downwind direction is connected with a vacuum pump.

And B: and vacuumizing the growth system until the air pressure reaches below 10Pa, setting the growth temperature at 370 ℃, wherein most of the metal substrates have certain catalytic reduction capacity at the temperature to promote C-C bond breakage and carbon atom rearrangement on the benzene ring, and meanwhile, the phenylenediamine molecules can maintain the stability of C-N bonds at the temperature below 500 ℃, so that the nitrogen-doped graphene can be obtained. Setting the flow of argon gas as 100sccm, maintaining the internal air pressure of the growth cavity as 60Pa, and under lower pressure, the molecules of the raw material have freer movement capability, which is beneficial to the rearrangement of the molecules to form the nitrogen-doped graphene.

And C: the method is characterized in that the phenylenediamine is kept at the temperature lower than 50 ℃, the saturated vapor pressure temperature of the phenylenediamine is lower (about 100 ℃), the temperature of the phenylenediamine is controlled at 40 ℃, so that the raw materials are prevented from being excessively volatilized, meanwhile, the sufficient supply of the growth raw materials can be ensured, and each raw material molecule can be utilized to the maximum extent. The growth time was about 70 minutes.

Step D: after the growth is finished, after the temperature of the growth cavity is reduced to room temperature, the growth cavity is cleaned by argon gas for three times, the vacuum pump is turned off, the growth cavity is filled with argon gas, after the air pressure in the cavity is close to atmospheric pressure, the cavity is opened, the growth substrate is taken out, and the metal material with the large area and the small layer of nitrogen-doped graphene paved on the surface is obtained, namely the nitrogen-doped graphene @ silver material. Compared with the existing chemical vapor deposition, the preparation method is simple and safe in operation, the prepared nitrogen-doped graphene product is high in quality, and the nitrogen content of the graphene is 25%.

Example 6

Step A: the method comprises the steps of placing a growth substrate polycrystalline nickel foil with the thickness of 40 mu m in a growth cavity of a CVD (chemical vapor deposition) tube furnace, placing a growth raw material nitrobenzene at the upwind position of the growth cavity, connecting the growth cavity into a vacuum system, connecting a protective gas source (argon) and a reducing gas (hydrogen) in the upwind direction, wherein the volume ratio of the argon to the hydrogen is 9:1, and connecting a downwind vacuum pump.

And B: and vacuumizing the growth system until the air pressure reaches below 10Pa, setting the growth temperature at 300 ℃, wherein most of the metal substrates have certain catalytic reduction capacity at the temperature. And the C-N bond of the phenylenediamine molecule is kept stable at the temperature of below 500 ℃, so that the growth of the nitrogen-doped graphene is facilitated. The flow rate of the protective gas is set to be 200sccm, the internal gas pressure of the growth cavity is maintained to be 70Pa, and molecules of the raw material have relatively free mobility under relatively low pressure, so that the molecular rearrangement is facilitated to form the nitrogen-doped graphene.

And C: the temperature of the raw material aniline for growth is maintained at 30 ℃ so as to ensure that the raw material does not excessively volatilize, and simultaneously, the sufficient supply of the raw material for growth can be ensured, and each raw material molecule can be utilized to the maximum extent. The growth time was 60 minutes.

Step D: after the growth is finished, the temperature of the growth cavity is reduced to room temperature, the growth cavity is cleaned by argon gas for three times, the vacuum pump is turned off, the growth cavity is filled with argon gas, the cavity is opened after the air pressure in the cavity is close to atmospheric pressure, the growth substrate is taken out, and the metal material with the large area and few layers of nitrogen-doped graphene paved on the surface is obtained, namely the nitrogen-doped graphene @ nickel material, and the nitrogen content is about 9%.

First embodiment of effects: electrochemical impedance testing

The method comprises the steps of carrying out three-electrode system on an electrochemical workstation CHI660e, using an Ag/AgCl electrode as an auxiliary electrode and a platinum sheet electrode as a reference electrode, using single crystal copper foils (control groups) which do not undergo nitrogen-doped graphene growth, graphene copper clad materials (graphene @ copper) which grow by a traditional CVD method and nitrogen-doped graphene @ copper sheets prepared in examples 1-4 as working electrodes respectively, using an electrolyte solution of 3.5 wt% of sodium chloride water solution as the electrolyte, carrying out impedance test after the working electrodes reach an environment stable state after being soaked in the sodium chloride solution for 30min, wherein the test frequency range is 10^-2～10^-5Hz, amplitude of + -5 mV, scan rate of 10mV/s, and the test results are shown below,

TABLE 1 results of impedance testing

As can be seen from Table 1, the real impedance parts of the nitrogen-doped graphene @ copper sheets prepared in the embodiments 1-4 of the invention are all 351.8KΩ -cm²The impedance real part of the nitrogen-doped graphene @ copper sheet is obviously higher than that of a single-crystal copper foil control group and a graphene @ copper group, and the impedance real part of the nitrogen-doped graphene @ copper sheet has a certain positive correlation with the nitrogen content. The larger the real part of the impedance is, the lower the corrosion rate is, and the better the corrosion resistance is, so that the nitrogen-doped graphene @ metal material has the excellent corrosion resistance compared with the copper substrate and the unmodified graphene @ copper material thereof.

Effect embodiment two: test for Oxidation resistance

As shown in fig. 1, pure copper sheets (control) and three groups of nitrogen-doped graphene @ copper foils (nitrogen-doped graphene @ copper sheets prepared in example 4) were subjected to an oxidation resistance test, wherein a is a photograph of the control and test groups in an initial state when they were left at room temperature; b is a photograph of the control group and the test group after being placed on a heating plate (exposed to heat in air) at 200 ℃ for 10 minutes; further heating, c is a photograph of the control group and the test group after being placed on a heating plate (exposed to air for heating) at 200 ℃ for 20 minutes. In the initial stage, all the copper sheets are placed in the air environment at room temperature, and the surfaces of the copper sheets have no visible difference. Two groups of copper sheets are placed on a heating plate at 200 ℃ and heated in the air, after 10 minutes, the surface of the untreated copper sheet changes from golden yellow to mauve, the copper sheet is completely oxidized, and after the copper sheet is protected by nitrogen-doped graphene, no macroscopic change exists after 10 minutes. When the heating time is continued to be prolonged, the pure copper sheet is completely oxidized, and further change cannot be observed; the copper sheet protected by the nitrogen-doped graphene is gradually oxidized. Therefore, we can prove that in this case, the nitrogen-doped graphene grown by the chemical vapor deposition method can well protect the metal substrate from the influence of chemical environment and high-temperature environment, and can improve the service life of the metal.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.