CN112707389A - Method for preparing wrinkle-free graphene membrane - Google Patents
Method for preparing wrinkle-free graphene membrane Download PDFInfo
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- CN112707389A CN112707389A CN202110018341.1A CN202110018341A CN112707389A CN 112707389 A CN112707389 A CN 112707389A CN 202110018341 A CN202110018341 A CN 202110018341A CN 112707389 A CN112707389 A CN 112707389A
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- C01B32/186—Preparation by chemical vapour deposition [CVD]
Abstract
The invention belongs to the field of growth of graphene materials, and relates to a method for preparing a wrinkle-free graphene film, which comprises the following steps: s1, cleaning the metal substrate and drying the metal substrate; s2, placing the dried copper foil in a chemical vapor deposition vacuum system; s3, introducing a mixed gas of hydrogen and argon into the system, raising the temperature from room temperature to 1060-1140 ℃ within 60-70min, and annealing at the temperature for 30-60 min; s4, introducing a gaseous carbon source into the system, and growing graphene on the surface of the metal substrate; s5, after the growth is finished, naturally cooling the system to room temperature; the sample was removed. The method comprises the step of growing a wrinkle-free graphene film with a plurality of additional layer crystal domains on the surface of a metal substrate by adjusting hydrogen partial pressure factors in a chemical vapor deposition method. The formation of the additional layer weakens van der Waals interaction between the graphene film and the substrate, so that the graphene film without folds can be obtained.
Description
Technical Field
The invention belongs to the field of growth of graphene materials, and relates to a method for preparing a wrinkle-free graphene film.
Background
Graphene is an ideal two-dimensional crystal composed of a single layer of carbon atoms. After graphene was stripped from professor geom and professor Novoselov in 2004, scientists successively found that graphene has many excellent mechanical, optical and electrical properties, including high transmittance, high carrier mobility, and high mechanical strength, among others. Therefore, the graphene becomes an excellent material for preparing high-performance field effect transistors, flexible displays and photoelectric devices. These potential applications have prompted the development of various techniques for the preparation of graphene, particularly the chemical vapor deposition preparation of graphene.
In recent years, graphene has been prepared by chemical vapor deposition on various transition metal substrates, particularly copper substrates. Due to the unique 'self-limiting growth' mechanism, large-area single-layer graphene can be easily obtained on a copper substrate. However, the graphene prepared by the chemical vapor deposition method often has many defects, such as grain boundaries, wrinkles and the like. Wherein the formation of graphene wrinkles is due to a strong interaction between graphene and a metal substrate and different thermal expansion coefficients. The formation of wrinkles can reduce the mobility, mechanical strength, thermal conductivity and the like of graphene, and greatly influences the performance and application of graphene. Therefore, the method for reducing the wrinkles of the graphene or preparing the wrinkle-free graphene has great significance for the application of the graphene.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides a method for preparing a wrinkle-free graphene film. The method comprises the step of growing a wrinkle-free graphene film with a plurality of additional layer crystal domains on the surface of a metal substrate by adjusting hydrogen partial pressure factors in a chemical vapor deposition method. The method has the advantages of easily controlled experimental parameters, convenient operation and convenience for low-cost batch production of the wrinkle-free graphene.
The technical scheme adopted by the invention for solving the technical problems in the prior art is as follows:
a method of making a wrinkle-free graphene membrane, comprising the steps of:
s1, ultrasonically cleaning the metal substrate with a proper amount of acetone, absolute ethyl alcohol and deionized water in sequence, and then drying the metal substrate with nitrogen;
s2, putting the dried copper foil into a quartz boat, putting the quartz boat and the copper foil into a chemical vapor deposition system together, and vacuumizing to below 1.0 Pa;
s3, introducing a mixed gas of hydrogen and argon into the chemical vapor deposition system, starting a temperature raising program, raising the temperature from room temperature to 1060-1140 ℃ within 60-70min, and annealing for 30-60min at the temperature;
s4, introducing a gaseous carbon source into the chemical vapor deposition system, and growing graphene on the surface of the metal substrate;
s5, after the growth is finished, closing the gaseous carbon source, and naturally cooling the system to room temperature under the protection of hydrogen and argon; taking out a sample, a wrinkle-free graphene film with a plurality of additional layer crystal domains can be obtained on the metal substrate.
As a preferred embodiment, the metal substrate described in S1 is liquid copper on a resolidified copper or tungsten foil.
As a preferred embodiment, in S3, introducing a mixed gas of hydrogen and argon into the chemical vapor deposition system, starting a temperature raising procedure, raising the temperature from room temperature to 1060-1140 ℃ within 60-70min, and annealing at the temperature for 30-60 min; then the temperature was reduced to 1060 ℃ at a rate of 0.5 ℃/min.
As a preferred embodiment, the flow ratio of the hydrogen gas and argon gas mixture gas described in S3 is 1: 5-1: 20.
as a preferred example, the growth time described in S4 is 5-60 min.
As a preferred example, the gaseous carbon source in S5 is any one of methane, ethane, ethylene and acetylene, and the flow rate of the gaseous carbon source is 0.5 to 6 sccm.
As a preferred embodiment, the wrinkle-free graphene film described in S5 is a single layer except for the domain regions of the additional layer.
The invention has the advantages and positive effects that:
the invention grows the wrinkle-free graphene film with a plurality of additional layer crystal domains on the surface of the metal substrate by adjusting the hydrogen partial pressure factor in the chemical vapor deposition method. The formation of the additional layer weakens van der Waals interaction between the graphene film and the substrate, so that the graphene film without folds can be obtained. The method has the advantages of easy control of experimental parameters, convenient operation and convenience for low-cost batch production of the wrinkle-free graphene.
Drawings
FIG. 1 is a schematic view of a chemical vapor deposition system used in an embodiment of the present invention; wherein, 1 is a temperature control area, 2 is a quartz tube inner tube, 4 is a quartz tube outer tube, and 3 is a quartz boat for placing a metal substrate;
fig. 2 is characterization data of a wrinkle-free graphene film with several additional layer domains grown on liquid copper in example 1, wherein fig. 2a is an optical microscope photograph of the sample after oxidation; fig. 2b is a scanning electron microscope photograph of a sample before oxidation, and fig. 2c is a typical raman spectrum of a double-layer graphene region and a single-layer graphene film without wrinkles;
FIGS. 3a and 3b are respectively an optical microscope photograph after oxidation and a scanning electron microscope photograph before oxidation of a sample of a single-layer wrinkled graphene film grown without an additional layer on liquid copper in comparative example 1;
FIGS. 4a and 4b are respectively an optical microscope photograph after oxidation and a scanning electron microscope photograph before oxidation of a wrinkle-free graphene film sample with several additional layer domains grown on liquid copper in example 2;
FIGS. 5a and 5b are respectively an optical microscope photograph after oxidation and a scanning electron microscope photograph before oxidation of a wrinkle-free graphene film sample with several additional layer domains grown on liquid copper in example 3;
FIG. 6 is a scanning electron microscope photomicrograph of a wrinkle-free graphene film with additional layer domains grown on re-solidified copper foil in example 4;
fig. 7a and 7b are respectively an optical microscope photograph and a scanning electron microscope photograph of a sample of the single-layer folded graphene island without additional layer growth on the liquid copper in the comparative example 3 after oxidation.
Detailed Description
For a further understanding of the invention, its nature and utility, reference should be made to the following examples, which are set forth in the following detailed description, taken in conjunction with the accompanying drawings, in which:
as shown in fig. 1-7, the present invention discloses a method for preparing a wrinkle-free graphene film, comprising the steps of:
s1, ultrasonically cleaning the metal substrate with a proper amount of acetone, absolute ethyl alcohol and deionized water in sequence, and then drying the metal substrate with nitrogen;
s2, putting the dried copper foil into a quartz boat, putting the quartz boat and the copper foil into a chemical vapor deposition system together, and vacuumizing to below 1.0 Pa;
s3, introducing a mixed gas of hydrogen and argon into the chemical vapor deposition system, starting a temperature raising program, raising the temperature from room temperature to 1060-1140 ℃ within 60-70min, and annealing for 30-60min at the temperature;
s4, introducing a gaseous carbon source into the chemical vapor deposition system, and growing graphene on the surface of the metal substrate;
s5, after the growth is finished, closing the gaseous carbon source, and naturally cooling the system to room temperature under the protection of hydrogen and argon; taking out a sample, a wrinkle-free graphene film with a plurality of additional layer crystal domains can be obtained on the metal substrate.
Preferably, the metal substrate described in S1 is liquid copper on a resolidified copper or tungsten foil.
Preferably, the flow ratio of the hydrogen gas to argon gas mixture gas described in S3 is 1: 5-1: 20.
preferably, the growth time described in S4 is 5-60 min.
Preferably, the gaseous carbon source in S5 is any one of methane, ethane, ethylene and acetylene, and the flow rate of the gaseous carbon source is 0.5 to 6 sccm.
Preferably, the wrinkle-free graphene film described in S5 is a single layer except for the domain regions of the additional layer.
The method for preparing the graphene film without wrinkles is described in detail below by using several examples, and the process parameters of each example are shown in table 1:
TABLE 1 graphene film preparation Process parameters
Example 1:
the embodiment discloses a method for preparing a wrinkle-free graphene film, which specifically comprises the following steps:
s1, cutting the copper foil with the thickness of 250 microns and the tungsten foil with the thickness of 500 microns into square substrates with proper sizes and flattening; in order to remove pollutants on the surfaces of copper and tungsten, ultrasonically cleaning the substrate in acetone and ethanol for 15min respectively, then repeatedly flushing the substrate with deionized water, and drying the substrate under the blowing of nitrogen;
s2, directly placing the copper foil on the tungsten foil and pushing the tungsten foil and the tungsten foil into a heating area of a chemical vapor deposition system together, as shown in figure 1; before graphene growth, vacuumizing the whole system to below 1.0 Pa;
s3, setting the flow ratio as 1: filling 20 hydrogen-argon mixed gas into a quartz tube; then heating the system from room temperature to 1100 ℃ within 60min, and annealing at 1100 ℃ for 30 min;
s4, introducing 6sccm methane into a chemical vapor deposition system, growing for 20min, and obtaining a wrinkle-free graphene film with a plurality of additional layer crystal domains on liquid copper; closing methane after the growth is finished;
and S5, naturally cooling the chemical vapor deposition system to room temperature, and taking out the sample.
Example 2
This example differs from example 1 in that: the hydrogen-argon mixture gas flow ratio in step S3 was changed to 1: and 15, keeping other steps unchanged, and obtaining the sample to be detected.
Example 3
This example differs from example 1 in that: the hydrogen-argon mixture gas flow ratio in step S3 was changed to 1: and 5, keeping other steps unchanged to obtain the sample to be detected.
Example 4
S1, cutting the copper foil with the thickness of 250 microns and the tungsten foil with the thickness of 500 microns into square substrates with proper sizes and flattening; in order to remove pollutants on the surfaces of copper and tungsten, ultrasonically cleaning the substrate in acetone and ethanol for 15min respectively, then repeatedly flushing the substrate with deionized water, and drying the substrate under the blowing of nitrogen;
s2, directly placing the copper foil on the tungsten foil and pushing the tungsten foil and the tungsten foil into a heating area of a chemical vapor deposition system together, as shown in figure 1; before graphene growth, vacuumizing the whole system to below 1.0 Pa;
s3, setting the flow ratio as 1: filling 20 hydrogen-argon mixed gas into a quartz tube; then heating the system from room temperature to 1140 ℃ within 70min, annealing for 60min at 1140 ℃, then cooling to 1060 ℃ at the speed of 0.5 ℃/min, wherein the temperature is lower than the melting point of copper, and then solidifying the liquid copper;
s4, introducing 3sccm methane into a chemical vapor deposition system, growing for 20min, and obtaining a wrinkle-free graphene film with a plurality of additional layer crystal domains on the re-solidified copper foil; closing methane after the growth is finished;
and S5, naturally cooling the system to room temperature, and taking out the sample.
Example 5
This example differs from example 1 in that: step S4, introducing 6sccm methane into the chemical vapor deposition system, and growing for 5 min; and other steps are unchanged, and the sample to be detected is obtained.
Example 6
This example differs from example 1 in that: the hydrogen-argon mixture gas flow ratio in step S3 was changed to 1: 10; the flow rate of methane in S4 was changed to 3sccm, and the other steps were not changed, to obtain a sample to be tested.
Example 7
This example differs from example 1 in that: the hydrogen-argon mixture gas flow ratio in step S3 was changed to 1: 15; and changing the growth time in the S4 to 60min, and keeping the other steps unchanged to obtain the sample to be detected.
Example 8
This example differs from example 1 in that: the hydrogen-argon mixture gas flow ratio in step S3 was changed to 1: 5; changing the growth time in S4 to 10 min; the flow rate of methane in S4 was changed to 1sccm, and the other steps were not changed, to obtain a sample to be tested.
Example 9
This example differs from example 1 in that: the hydrogen-argon mixture gas flow ratio in step S3 was changed to 1: 5, heating at 1120 ℃; the flow rate of methane in S4 was changed to 0.5sccm, and the other steps were not changed, to obtain a sample to be tested.
Example 10
This example differs from example 1 in that: the hydrogen-argon mixture gas flow ratio in step S3 was changed to 1: 5, heating at 1140 ℃; the flow rate of methane in S4 was changed to 0.5sccm, and the other steps were not changed, to obtain a sample to be tested.
Comparative example 1
This example differs from example 1 in that: the hydrogen-argon mixture gas flow ratio in step S3 was changed to 1: and 1, keeping other steps unchanged to obtain the sample to be detected.
Comparative example 2
This example differs from example 1 in that: the hydrogen-argon mixture gas flow ratio in step S3 was changed to 1: and 2, keeping other steps unchanged to obtain the sample to be detected.
Comparative example 3
This example differs from example 1 in that: the hydrogen-argon mixture gas flow ratio in step S3 was changed to 1: and 25, keeping other steps unchanged, and obtaining the sample to be detected.
The samples subjected to oxidation treatment of the 10 examples and the 3 comparative examples are placed under an optical microscope for observation, the surface wrinkle information of the samples is preliminarily judged, the samples before oxidation are characterized by a scanning electron microscope to further judge the wrinkle information, and the quality of graphene is characterized by using a Raman spectrum.
Fig. 2 is characterization data of a wrinkle-free graphene film with several additional layer domains grown on liquid copper in example 1, wherein fig. 2a is an optical microscope photograph of the sample after oxidation. FIG. 2b is a scanning electron micrograph of the sample before oxidation. After oxidation treatment (placing a graphene sample on a hot plate in an air atmosphere for heating at 200 ℃ for 20min), introducing oxygen atoms to rapidly change the lattice structure of the copper surface, wherein the change can cause tensile strain of coupled graphene crystals; finally, the stress generated in the graphene due to the volume expansion of the copper surface is released by the formation of cracks. The interaction between the metal substrate and the graphene is strong, and in the rapid cooling stage, the polarities of the thermal expansion coefficients between the graphene and the substrate are opposite, so that wrinkles are formed. But the graphene samples with the additional layers did not crack after oxidation because the growth of the additional smectic domains increased the distance between the single layer graphene region near the double layer graphene and the metal substrate. This decouples the van der waals interaction between single layer graphene and the metal substrate, and the grown graphene is not affected by the expanded Cu substrate during cooling and oxidation. The single-layer graphene film near the double-layer graphene is not obvious after oxidationShown in fig. 2 a. Figure 2b is a typical scanning electron micrograph showing a single layer graphene film without wrinkles. FIG. 2c is a Raman spectrum of double-layer graphene and single-layer graphene without wrinkles, without a distinct D peak (1350 cm)-1) High quality graphene is shown; illustrative example 1 a wrinkle-free single-layer graphene film with several additional layer domains can be prepared.
The single-layer graphene film grown without the additional layer can be obtained by changing the proportion of the hydrogen, and as shown in fig. 3a, the single-layer graphene film grown without the additional layer generates a large number of cracks after the oxidation process, which is obviously compared with the single-layer graphene film with a plurality of additional layer crystal domains. Figure 3b is a typical scanning electron micrograph showing a densely packed graphene monolayer film. The formation of the additional layer is regulated and controlled by controlling the proportion of hydrogen, and the existence of the additional layer weakens the interaction between the graphene film and the substrate to grow the wrinkle-free graphene. It can be seen that the single layer graphene film grown without the additional layer wrinkles densely and generates a large number of cracks after the oxidation treatment.
Fig. 4a and 4b are an optical microscope photograph after oxidation and a scanning electron microscope photograph before oxidation, respectively, of a wrinkle-free graphene film sample with several additional layer domains grown on liquid copper in example 2.
Fig. 5a and 5b are an optical microscope photograph after oxidation and a scanning electron microscope photograph before oxidation, respectively, of a wrinkle-free graphene film sample with several additional layer domains grown on liquid copper in example 3.
Fig. 6 is a scanning electron microscope photomicrograph of a wrinkle-free graphene film with additional layer domains grown on re-solidified copper foil in example 4.
Fig. 7a and 7b are respectively an optical microscope photograph and a scanning electron microscope photograph of a sample of the single-layer folded graphene island without additional layer growth on the liquid copper in the comparative example 3 after oxidation.
Experimental results show that examples 1 to 10 can all obtain wrinkle-free graphene films with several additional layer crystal domains, while comparative examples 1 to 3 can obtain single-layer wrinkle-free graphene grown without additional layers.
The embodiments described herein are only some, and not all, embodiments of the invention. Based on the above explanations and guidance, those skilled in the art can make modifications, improvements, substitutions, and the like on the embodiments based on the present invention and examples, but all other embodiments obtained without innovative research fall within the scope of the present invention.
Claims (7)
1. A method of preparing a wrinkle-free graphene membrane, characterized by: the method comprises the following steps:
s1, ultrasonically cleaning the metal substrate with a proper amount of acetone, absolute ethyl alcohol and deionized water in sequence, and then drying the metal substrate with nitrogen;
s2, putting the dried copper foil into a quartz boat, putting the quartz boat and the copper foil into a chemical vapor deposition system together, and vacuumizing to below 1.0 Pa;
s3, introducing a mixed gas of hydrogen and argon into the chemical vapor deposition system, starting a temperature raising program, raising the temperature from room temperature to 1060-1140 ℃ within 60-70min, and annealing for 30-60min at the temperature;
s4, introducing a gaseous carbon source into the chemical vapor deposition system, and growing graphene on the surface of the metal substrate;
s5, after the growth is finished, closing the gaseous carbon source, and naturally cooling the system to room temperature under the protection of hydrogen and argon; taking out a sample, a wrinkle-free graphene film with a plurality of additional layer crystal domains can be obtained on the metal substrate.
2. The method of preparing a wrinkle-free graphene film of claim 1, wherein: the metal substrate described in S1 is liquid copper on a resolidified copper foil or tungsten foil.
3. The method of preparing a wrinkle-free graphene film of claim 1, wherein: s3, introducing a mixed gas of hydrogen and argon into the chemical vapor deposition system, starting a temperature raising program, raising the temperature from room temperature to 1060-1140 ℃ within 60-70min, and annealing for 30-60min at the temperature; then the temperature was reduced to 1060 ℃ at a rate of 0.5 ℃/min.
4. The method of preparing a wrinkle-free graphene film of claim 1, wherein: the flow ratio of the hydrogen and argon mixed gas in the S3 is 1: 5-1: 20.
5. the method of preparing a wrinkle-free graphene film of claim 1, wherein: the growth time described in S4 is 5-60 min.
6. The method of preparing a wrinkle-free graphene film of claim 1, wherein: in S5, the gaseous carbon source is any one of methane, ethane, ethylene and acetylene, and the flow rate of the gaseous carbon source is 0.5-6 sccm.
7. The method of preparing a wrinkle-free graphene film of claim 1, wherein: the wrinkle-free graphene film described in S5 is a single layer except for the additional layer domain region.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114635120A (en) * | 2022-03-16 | 2022-06-17 | 北京石墨烯技术研究院有限公司 | Substrate for growing graphene film, graphene film and preparation method of substrate |
| CN114854200A (en) * | 2022-05-17 | 2022-08-05 | 广东墨睿科技有限公司 | Preparation method of high-thermal-conductivity graphene composite thermal grease |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109850878A (en) * | 2019-04-02 | 2019-06-07 | 华南理工大学 | A kind of graphene and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109850878A (en) * | 2019-04-02 | 2019-06-07 | 华南理工大学 | A kind of graphene and preparation method thereof |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114635120A (en) * | 2022-03-16 | 2022-06-17 | 北京石墨烯技术研究院有限公司 | Substrate for growing graphene film, graphene film and preparation method of substrate |
| CN114854200A (en) * | 2022-05-17 | 2022-08-05 | 广东墨睿科技有限公司 | Preparation method of high-thermal-conductivity graphene composite thermal grease |
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Application publication date: 20210427 |