Copper-based multilayer graphene and preparation method thereof

Abstract

The invention relates to copper-based multilayer graphene and a preparation method thereof. Comprising the following steps: growing first-layer graphene on the surface of a copper substrate; controlling the temperature to enable the surface of the copper substrate to deform, enabling the first-layer graphene to be locally separated from the copper substrate, enabling the first-layer graphene to generate cracks, and exposing part of the copper substrate; and under the catalytic action of the copper substrate, the carbon source gas forms carbon atoms on the surface of the copper substrate, the carbon atoms are stacked and grown again at the cracks to form multi-layer graphene, the multi-layer graphene is diffused and grown along the cracks, and finally, the multi-layer graphene and the first-layer graphene jointly form complete multi-layer graphene on the surface of the copper substrate. According to the method disclosed by the invention, after the primary growth of the graphene is finished, the copper base is exposed through rapid cooling and etching to play a catalytic role in secondary growth, and finally, the continuous, high-quality and high-coverage multilayer graphene is obtained. Under the condition of not wrapping copper foil to improve the catalytic decomposition efficiency of carbon-containing gas, the self-limiting growth mechanism of the copper foil is broken through, and the multi-layer graphene is prepared on the surface of the copper foil.

Description

Technical Field

[0001] The invention relates to the field of graphene film growth and preparation, and in particular to a copper-based multilayer graphene and a preparation method thereof. Background Art

[0002] Each carbon atom in graphene is sp2 hybridized, and three adjacent carbon atoms are bonded by covalent σ bonds and are 120° apart, thus forming a unique regular hexagonal structure. These regular hexagonal structures are arranged into a honeycomb-shaped single-layer two-dimensional planar crystal, forming a unique two-dimensional material. The electrons in the p orbital that are not involved in the hybridization form a large π bond, and the π electrons can move freely in the crystal, bringing unique electrical properties to graphene.

[0003] The carrier mobility of graphene at room temperature is as high as 2.0×10 5 cm 2 V -1 s -1 In comparison, the mobility of traditional semiconductor silicon materials is only 1.0×10 3 cm 2 V -1 s -1 Graphene can also sustain high current density, about 1 million times that of copper, and has a lower resistivity than copper, only 10 -6 Ωcm -1 This makes graphene have broad application prospects in the fields of energy, electronics, information and materials.

[0004] At present, high-quality graphene films are mainly prepared on copper substrates by chemical vapor deposition (CVD technology). The specific mechanism is as follows: Under high temperature, methane (or other carbon sources) is catalytically cracked on the bottom surface of the copper substrate to generate carbon atoms, and the cracked carbon atoms are reorganized on the surface of the copper substrate to form a graphene film. Since the formation of the graphene film requires a bare copper substrate to catalyze the cracking of methane to provide a carbon source, when the copper substrate is covered with graphene, its ability to catalyze the decomposition to form methane is weakened. When the surface of the copper substrate is completely covered with graphene, it can no longer catalyze the cracking of methane, so that the graphene film formed on the copper substrate is mainly a single layer. This mechanism is also called the surface self-limited growth process of the copper substrate.

[0005] Chinese patent application publication number CN116397211A discloses a method for preparing multilayer graphene based on chemical vapor deposition, and Chinese patent application publication number CN108706574A discloses a method for growing copper-based multilayer graphene. Both adopt the method of wrapping a layer of metal foil outside the deposition substrate to improve the catalytic decomposition efficiency of carbon-containing gas to prepare copper-based multilayer graphene. However, this method not only requires wrapping the metal foil outside the substrate, but also requires controlling the gap between the outer metal foil and the growing graphene substrate. The steps are complicated and are not conducive to the efficient preparation of copper-based multilayer graphene. Summary of the invention

[0006] In view of one or more of the problems existing in the prior art, the first aspect of the present invention provides a method for preparing copper-based multilayer graphene, comprising the following steps:

[0007] Growing a first layer of graphene on the surface of a copper substrate;

[0008] The surface of the copper substrate is deformed by controlling the temperature, so that the first layer of graphene is partially separated from the copper substrate, and cracks are generated in the first layer of graphene, exposing a portion of the copper substrate;

[0009] Under the catalytic action of the copper substrate, the carbon source gas forms carbon atoms on the surface of the copper substrate, and restacks and grows to form multilayer graphene at the cracks, and diffuses and grows multilayer graphene along the cracks, and finally forms a complete multilayer graphene on the surface of the copper substrate together with the first layer of graphene.

[0010] According to one aspect of the present invention, the growth of the multilayer graphene is performed by chemical vapor deposition in a CVD growth system, comprising:

[0011] Introducing a carbon source gas and a reducing gas into the CVD growth system to perform graphene nucleation; and

[0012] The ratio and flow rate of the carbon source gas and the reducing gas are adjusted to grow multilayer graphene on the surface of the copper substrate.

[0013] Preferably, before adjustment, the ratio of the carbon source gas to the reducing gas is 1:20 to 1:80; and / or

[0014] After adjustment, the ratio of the carbon source gas to the reducing gas is 1:2 to 1:8.

[0015] Preferably, the carbon source gas flow rate is controlled at 10-20 SCCM before adjustment, and the reducing gas flow rate is controlled at 400-800 SCCM before adjustment; and / or

[0016] The adjusted flow rate of the carbon source gas is 100-200 SCCM, and the adjusted flow rate of the reducing gas is 400-1600 SCCM.

[0017] Preferably, the nucleation time is ≥ 10 min.

[0018] Preferably, the nucleation temperature is ≥ 900°C.

[0019] Preferably, the temperature in the growth stage is 980°C to 1080°C.

[0020] Preferably, the growth time is ≥ 1 h.

[0021] According to one aspect of the present invention, after the growth of the first layer of graphene is completed, the ambient temperature is 980°C to 1080°C, nitrogen is used for cooling, the nitrogen flow rate is ≥2000SCCM, the cooling process time is ≤4h, and the cooling temperature is cooled to 300-400°C.

[0022] According to one aspect of the present invention, after cooling, the temperature is raised to 980° C. to 1080° C., and reducing gas is used during the heating process to further destroy the first layer of graphene;

[0023] Preferably, the flow rate of the reducing gas is 200 SCCM to 400 SCCM.

[0024] According to one aspect of the present invention, the copper substrate is first annealed before growing the first layer of graphene;

[0025] The annealing treatment step is: mounting the copper substrate on a graphite support, and then placing it in a CVD growth system, evacuating the vacuum, heating it to 980° C. to 1080° C., introducing the reducing gas, wherein the reducing gas flow rate is 800 SCCM, and the annealing time is ≥300 min;

[0026] Preferably, the copper substrate is oxygen-free rolled copper foil;

[0027] Preferably, the carbon source gas is one or a combination of methane, ethane and benzene.

[0028] According to one aspect of the present invention, the reducing gas is specifically hydrogen.

[0029] A second aspect of the present invention provides a copper-based multilayer graphene prepared by the above-mentioned method for preparing copper-based multilayer graphene.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention is based on the chemical vapor deposition process of the copper foil substrate. After the first growth is completed, the uneven expansion and contraction between the grains of the copper foil during its own recrystallization is used to produce fine protrusions or grooves and other surface deformations, thereby destroying the first layer of graphene on the surface and producing some exposed copper foil substrates, so that the copper foil substrate plays a role in catalyzing the cracking of carbon source gas in the subsequent secondary growth, and finally obtains continuous, high-quality, high-coverage multilayer graphene. This invention breaks through the self-limiting growth mechanism of copper foil without the need for external metal foil to improve the catalytic decomposition efficiency of carbon-containing gas, and realizes the controllable preparation of multilayer graphene on the surface of copper foil. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0033] Figure 1 It is a schematic diagram of the preparation method of copper-based multilayer graphene provided by the present invention;

[0034] Figure 2 is a histogram of the square resistance of multilayer graphene and single-layer graphene obtained according to an embodiment of the present invention;

[0035] Figure 3 is a scanning electron microscope image of a first layer of graphene obtained according to an embodiment of the present invention;

[0036] Figure 4 is a scanning electron microscope image after the first layer of graphene is destroyed according to one embodiment of the present invention;

[0037] Figure 5 is a scanning electron microscope image of multilayer graphene obtained according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to facilitate the understanding of the present invention, the present invention will be described more fully below. Preferred embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0040] This article relates to numerical ranges. Unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0041] The temperature parameters herein, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows for temperature fluctuations within the precision range of instrument control.

[0042] Figure 1 A schematic diagram of a method for preparing copper-based multilayer graphene provided in one embodiment of the present invention.

[0043] According to a specific embodiment of the present invention, a method for preparing copper-based multilayer graphene is provided, such as Figure 1 As shown, the method includes the following steps S1-S3:

[0044] Step S1, growing a first layer of graphene on the surface of a copper substrate.

[0045] In some embodiments of the present invention, a first layer of graphene is grown on the surface of a copper substrate using conventional chemical vapor deposition.

[0046] In some embodiments of the present invention, the copper substrate is mounted on a graphite support and then placed in a CVD growth system for annealing.

[0047] The CVD growth system is a whole composed of equipment and instruments required for implementing the chemical vapor deposition method. In the present invention, the CVD growth system is a system required for the entire process of generating a multilayer graphene film on the surface of a metal substrate using the chemical vapor deposition method.

[0048] In some embodiments of the present invention, the copper substrate is made of oxygen-free rolled copper foil, and the processing stripes, impurities and metal oxides on the surface of the copper substrate are removed by annealing.

[0049] High temperature annealing can improve the surface flatness and dimensional stability of copper foil. During the cold processing of copper foil, deformation and stacking defects will cause the copper surface to be uneven and dimensional changes. High temperature annealing can rearrange the crystals in the copper foil, reduce deformation and defects, and thus improve surface flatness and dimensional stability.

[0050] Rolled copper foil is the original foil (also called rough foil) made by repeatedly rolling copper plates, and is roughened according to requirements. The oxygen-free rolled copper foil has the characteristic of only 0.001% oxygen content and high tensile strength.

[0051] In some embodiments of the present invention, the annealing temperature is 980°C to 1080°C. If the annealing temperature is too low (lower than 980°C), the surface of the copper substrate cannot be effectively recrystallized, which is not conducive to the growth of large-sized graphene sheets; if the annealing temperature is too high (>1080°C), the surface of the copper substrate remains in a molten state, which is also not conducive to the growth of large-sized graphene sheets. In some specific examples, the annealing temperature can be 980°C, 1000°C, 1020°C, 1040°C, 1060°C, 1080°C, etc.

[0052] In some embodiments of the present invention, hydrogen is used as a reducing atmosphere during the annealing process, and the hydrogen flow rate is 800 SCCM.

[0053] In some embodiments of the present invention, the annealing time is ≥ 300 min.

[0054] Figure 3 This is a scanning electron microscope image of the first layer of graphene obtained according to an embodiment of the present invention; the surface of the first layer of graphene is subject to the self-limiting growth mechanism of the copper foil surface and is mainly a single layer.

[0055] Step S2, controlling the temperature to cause deformation on the surface of the copper substrate, thereby partially separating the first layer of graphene from the copper substrate, and causing cracks in the first layer of graphene to expose a portion of the copper substrate.

[0056] In some embodiments of the present invention, the CVD system is quickly cooled down after the growth of graphene is completed. The cooling process can readjust the grain structure on the surface of the copper substrate, so that some fine protrusions and grooves appear on the surface of the copper substrate, and the copper substrate is partially separated from the first layer of graphene, which can provide space for the subsequent growth of multi-layer graphene. In addition, the protrusions and other deformations produced on the copper substrate can also destroy the first layer of graphene, causing micron-sized cracks or holes in the first layer of graphene, providing a channel for the carbon source gas to contact the copper substrate.

[0057] In some embodiments of the present invention, after the first layer of graphene is grown, the ambient temperature is between 980°C and 1080°C, the temperature is controlled by cooling the surface by introducing nitrogen gas with a flow rate of ≥2000SCCM, the cooling time is ≤4h, and the temperature after cooling is 300-400°C. In some specific examples, the cooling time can be 1h, 2h, 3h, 4h, etc., and the temperature after cooling can be 300°C, 350°C, 400°C, etc.

[0058] In some embodiments of the present invention, the temperature of the CVD system is increased to 980°C to 1080°C after the cooling is completed, and a reducing gas with a flow rate of 200SCCM to 400SCCM is introduced simultaneously during the heating process to further damage the monolayer graphene on the surface of the copper substrate, so that the monolayer graphene produces micron-scale cracks, and the carbon source gas can contact the copper substrate through these cracks to provide a catalytic environment for the subsequent growth of graphene. In some specific examples, the temperature after heating can be 980°C, 1000°C, 1020°C, 1040°C, 1060°C, 1080°C, etc., and the flow rate of the reducing gas can be 200SCCM, 300SCCM, 400SCCM, etc.

[0059] In some embodiments of the present invention, the introduced reducing gas is specifically hydrogen. The hydrogen atmosphere has a destructive effect on the first layer of graphene. Hydrogen can react chemically with carbon atoms on the surface of graphene to form compounds such as methane, thereby etching away carbon atoms on the surface of graphene to form nanoscale holes or defects. If the hydrogen atmosphere is not introduced, the first layer of graphene will be slightly damaged, and insufficient exposed copper substrate will be produced for subsequent multi-layer graphene growth.

[0060] In some embodiments of the present invention, the role of reducing gas such as hydrogen also includes preventing oxygen from entering the CVD system, as oxygen will cause copper oxide to form on the copper surface, thereby weakening the catalytic effect of copper on the growth of graphene.

[0061] Figure 4 The figure is a scanning electron microscope image of the first layer of graphene after being destroyed according to an embodiment of the present invention; after the copper substrate is deformed by cooling to destroy the first layer of graphene, and the copper substrate is further destroyed by the reducing gas, cracks are locally generated in the first layer of graphene, and the shape and distribution of the cracks are shown in the dotted box A. The bottom copper substrate can be exposed through the cracks, thereby providing an active surface for the subsequent catalytic cracking of the carbon source gas. The generation of the cracks also provides a channel for the diffusion of the carbon source;

[0062] Step S3, under the catalytic action of the copper substrate, the carbon source gas forms active carbon atoms on the surface of the copper substrate, and restacks and grows to form multilayer graphene at the cracks, and diffuses and grows multilayer graphene along the cracks, and finally forms a complete multilayer graphene on the surface of the copper substrate together with the first layer of graphene film.

[0063] In some embodiments of the present invention, step S3 is to grow the multilayer graphene by chemical vapor deposition in a CVD growth system, including step S301 and step S302:

[0064] Step S301: introducing a carbon source gas and a reducing gas into a CVD growth system to perform graphene nucleation.

[0065] In some embodiments of the present invention, the ratio of the carbon source gas to the reducing gas is 1:20 to 1:80, preferably 1:40 to 1:80. In some specific examples, the ratio of the carbon source gas to the reducing gas can be 1:20, 1:30, 1:40, 1:50, 1:60, 1:70 or 1:80.

[0066] In some embodiments of the present invention, the carbon source gas used for nucleation may be methane, ethane, benzene or the like, and hydrogen may be used as the reducing atmosphere.

[0067] In some embodiments of the present invention, the carbon source gas flow rate is controlled at 10-20 SCCM, and the hydrogen flow rate is controlled at 400-800 SCCM. In some specific examples, the carbon source gas flow rate can be 10 SCCM, 15 SCCM, 20 SCCM, etc., and the hydrogen flow rate can be 400 SCCM, 500 SCCM, 600 SCCM, 700 SCCM, 800 SCCM, etc.

[0068] In some embodiments of the present invention, the nucleation time is ≥10 min, and the nucleation temperature is ≥900° C. It should be noted that if the nucleation temperature is lower than 900° C., the catalytic cracking of the carbon source gas by the copper foil substrate will be affected. If the nucleation time is less than 10 min, the number of graphene sheets produced at the catalytic active sites on the surface of the copper foil substrate is small and the size is small, which is not conducive to the preparation of large-area graphene sheets.

[0069] Step S302: adjusting the ratio and flow rate of the carbon source gas and the reducing gas to grow multilayer graphene on the surface of the copper substrate.

[0070] In some embodiments of the present invention, the ratio of the carbon source gas to the reducing gas is adjusted from 1:20 to 1:80 to 1:2 to 1:8, the adjusted carbon source gas flow rate is 100 to 200 SCCM, and the reducing gas flow rate is 400 to 1600 SCCM. In some specific examples, the adjusted ratio of the carbon source gas to the reducing gas can be 1:2, 1:4, 1:6, 1:8, etc.

[0071] In some embodiments of the present invention, the temperature of the growth stage is maintained between 980°C and 1080°C. If the temperature is too low (<980°C), it is not conducive to the bare copper substrate to catalyze the cracking of the carbon source gas and the growth of graphene sheets; if the temperature is too high (>1080°C), the surface of the copper substrate will melt, which will damage the grown graphene film. In some specific examples, the temperature of the growth stage can be 980°C, 1000°C, 1020°C, 1040°C, 1060°C, 1080°C, etc. In some embodiments of the present invention, the growth time of the growth stage is ≥1h. If the growth time is too short, the grown multilayer graphene is not complete and the quality is relatively poor.

[0072] In some embodiments of the present invention, when the first layer of graphene is destroyed and cracks appear, the copper substrate is exposed, and the carbon source gas contacts the copper substrate through the cracks. At the same time, the carbon source gas also diffuses into the growth space between the first layer of graphene and the copper substrate formed by the deformation caused by the destruction of the copper substrate. Under the catalytic action of the copper substrate, the carbon atoms generated after the carbon source gas is cracked are restacked and grown at the cracks to form multilayer graphene. At the same time, the carbon atoms spontaneously diffuse to the area with low carbon atom concentration between the first layer of graphene and the copper substrate. The diffused carbon atoms grow multilayer graphene again along the multilayer graphene that is restacked and grown at the cracks, and finally form a complete multilayer graphene on the surface of the copper substrate together with the first layer of graphene film.

[0073] According to another specific embodiment of the present invention, a copper-based multilayer graphene is provided.

[0074] In some embodiments of the present invention, the surface resistance of the multilayer graphene provided by the present invention is 400-450Ω / □

[0075] Figure 5 is a scanning electron microscope image of multilayer graphene obtained according to one embodiment of the present invention; Figure 5 As shown, multilayer graphene breaks through the self-limiting growth mechanism of copper foil, and widely distributed and continuous multilayer regions can be observed on the surface.

[0076] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0077] In the following embodiments, the preparation of the first graphene film layer can be accomplished by conventional chemical vapor deposition.

[0078] Example 1

[0079] A method for preparing copper-based multilayer graphene comprises the following steps:

[0080] Step S1, cutting the oxygen-free rolled copper foil into 50 mm×50 mm×25 um, mounting the copper foil on a graphite support, and transferring the copper foil to a CVD growth system;

[0081] After evacuation, the temperature of the CVD growth system was raised to 1000°C, and hydrogen gas with a flow rate of 800 SCCM was introduced for annealing for 330 minutes. After annealing, the first layer of graphene was grown on the surface of the copper substrate using a conventional method.

[0082] Step S2, cooling the copper-based first-layer graphene obtained in step S1 in a CVD system for 4 hours, flushing nitrogen during the cooling process, and ending the cooling step after cooling to 300° C. The copper substrate is deformed by cooling, thereby destroying the first-layer graphene;

[0083] The temperature of the CVD system was increased from 300°C to 1000°C, and hydrogen with a flow rate of 800 SCCM was introduced during the heating process as a reducing gas to further destroy the first layer of graphene.

[0084] Step S3, after the first layer of graphene is etched, graphene nucleation is performed, and methane gas with a flow rate of 10 SCCM and hydrogen gas with a flow rate of 800 SCCM are introduced, the ratio of hydrogen to methane is 80:1, the nucleation time is 10 minutes, and the nucleation temperature is 1080°C.

[0085] Step S4, after the nucleation is completed, graphene is grown, the methane flow rate is adjusted to 100 SCCM, the hydrogen flow rate is adjusted to 400 SCCM, the ratio of hydrogen to methane is adjusted to 4:1, the temperature of the growth stage is 1080°C, and the growth time is 1 hour. In the presence of cracks, the carbon source gas contacts the copper substrate and is catalytically cracked into active carbon atoms, which are rearranged and stacked into multilayer graphene at the cracks, and diffuse and grow along the cracks, and finally form multilayer graphene on the copper foil surface together with the first layer of graphene.

[0086] Example 2

[0087] A method for preparing copper-based multilayer graphene comprises the following steps:

[0088] Step S1, cutting the oxygen-free rolled copper foil into 50 mm×50 mm×25 um, mounting the copper foil on a graphite support, and transferring the copper foil to a CVD growth system;

[0089] After evacuation, the temperature of the CVD growth system was raised to 1080°C, and hydrogen gas with a flow rate of 800 SCCM was introduced for annealing for 330 minutes. After annealing, the first layer of graphene was grown on the surface of the copper substrate using a conventional method.

[0090] Step S2, cooling the copper-based first-layer graphene obtained in step S1 in a CVD system for 4 hours, injecting nitrogen during the cooling process, and ending the cooling step after cooling to 400° C. The copper substrate is deformed by cooling, thereby destroying the first-layer graphene;

[0091] The temperature of the CVD system was raised from 400°C to 1000°C, and hydrogen with a flow rate of 800 SCCM was introduced during the heating process as a reducing gas to further destroy the first layer of graphene.

[0092] Step S3, after the first layer of graphene is etched, graphene nucleation is performed, and methane gas with a flow rate of 20 SCCM and hydrogen gas with a flow rate of 400 SCCM are introduced, the ratio of hydrogen to methane is 20:1, the nucleation time is 15 minutes, and the nucleation temperature is 980°C.

[0093] Step S4, after the nucleation is completed, graphene is grown, the methane flow rate is adjusted to 200 SCCM, the hydrogen flow rate is adjusted to 400 SCCM, the ratio of hydrogen to methane is adjusted to 2:1, the temperature of the growth stage is 980°C, and the growth time is 1.5 hours. In the presence of cracks, the carbon source gas contacts the copper substrate and is catalytically cracked into active carbon atoms, which are rearranged and stacked into multilayer graphene at the cracks, and diffuse and grow along the cracks, and finally form multilayer graphene on the copper foil surface together with the first layer of graphene.

[0094] Example 3

[0095] A method for preparing copper-based multilayer graphene comprises the following steps:

[0096] Step S1, cutting the oxygen-free rolled copper foil into 50 mm×50 mm×25 um, mounting the copper foil on a graphite support, and transferring the copper foil to a CVD growth system;

[0097] After evacuation, the temperature of the CVD growth system was raised to 1050°C, and hydrogen gas with a flow rate of 800 SCCM was introduced for annealing for 300 minutes. After annealing, the first layer of graphene was grown on the surface of the copper substrate using a conventional method.

[0098] Step S2, cooling the copper-based first-layer graphene obtained in step S1 in a CVD system for 4 hours, injecting nitrogen during the cooling process, and ending the cooling step after cooling to 400° C. The copper substrate is deformed by cooling, thereby destroying the first-layer graphene;

[0099] The temperature of the CVD system was raised from 400°C to 1000°C, and hydrogen with a flow rate of 800 SCCM was introduced during the heating process as a reducing gas to further destroy the first layer of graphene.

[0100] Step S3, after the first layer of graphene is etched, graphene nucleation is performed, ethane gas with a flow rate of 10 SCCM and hydrogen gas with a flow rate of 800 SCCM are introduced, the ratio of hydrogen to methane is 80:1, and the nucleation time is 20 minutes.

[0101] Step S4, after nucleation is completed, graphene is grown, the ethane flow rate is adjusted to 100 SCCM, the hydrogen flow rate is adjusted to 400 SCCM, the ratio of hydrogen to ethane is adjusted to 4:1, the temperature of the growth stage is 980°C, and the growth time is 1 hour. In the presence of cracks, the carbon source gas contacts the copper substrate and is catalytically cracked into active carbon atoms, which are rearranged and stacked into multi-layer graphene at the cracks, and diffuse and grow along the cracks, and finally form multi-layer graphene on the copper foil surface together with the first layer of graphene.

[0102] like Figure 2 The figure shows the square resistance bar graph of multilayer graphene and single-layer graphene obtained according to an embodiment of the present invention; the single-layer graphene and multilayer graphene film grown by four-probe pair testing square resistance to characterize the integrity and quality of the graphene film. The surface square resistance of the single-layer graphene is 800-1000Ω / □; the surface square resistance of the multilayer graphene film is 400-450Ω / □.

[0103] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing copper-based multilayer graphene, characterized in that: include: Growing a first layer of graphene on the surface of a copper substrate; The surface of the copper substrate is deformed by controlling the temperature, so that the first layer of graphene is partially separated from the copper substrate, and cracks are generated in the first layer of graphene, exposing a portion of the copper substrate; Under the catalytic action of the copper substrate, the carbon source gas forms carbon atoms on the surface of the copper substrate, and restacks and grows to form multilayer graphene at the cracks, and diffuses and grows multilayer graphene along the cracks, and finally forms a complete multilayer graphene on the surface of the copper substrate together with the first layer of graphene.

2. The method for preparing copper-based multilayer graphene according to claim 1, characterized in that: The multilayer graphene is grown by chemical vapor deposition in a CVD growth system, comprising: Introducing a carbon source gas and a reducing gas into the CVD growth system to perform graphene nucleation; and The ratio and flow rate of the carbon source gas and the reducing gas are adjusted to grow multilayer graphene on the surface of the copper substrate.

3. The method for preparing copper-based multilayer graphene according to claim 2, characterized in that: The ratio of the carbon source gas to the reducing gas before adjustment is 1:20 to 1:80; and / or After adjustment, the ratio of the carbon source gas to the reducing gas is 1:2 to 1:

8.

4. The method for preparing copper-based multilayer graphene according to claim 2, characterized in that: The carbon source gas flow rate is controlled at 10-20 SCCM before adjustment, and the reducing gas flow rate is controlled at 400-800 SCCM before adjustment; and / or The adjusted flow rate of the carbon source gas is 100-200 SCCM, and the adjusted flow rate of the reducing gas is 400-1600 SCCM.

5. The method for preparing copper-based multilayer graphene according to claim 2, characterized in that: The graphene nucleation time is ≥10min; Preferably, the nucleation temperature of the graphene is ≥900°C; Preferably, the temperature during the graphene growth stage is 980°C to 1080°C; Preferably, the time of the graphene growth phase is ≥ 1 h.

6. The method for preparing copper-based multilayer graphene according to claim 1, characterized in that: The temperature control comprises: After the growth of the first layer of graphene is completed, the ambient temperature is 980°C to 1080°C, and nitrogen is used for cooling. The nitrogen flow rate is ≥2000SCCM, and the cooling process time is ≤4h, and the temperature is cooled to 300-400°C.

7. The method for preparing copper-based multilayer graphene according to claim 6, characterized in that: After cooling, the temperature is raised to 980° C. to 1080° C., and reducing gas is used during the heating process to further destroy the first layer of graphene; Preferably, the flow rate of the reducing gas is 200 SCCM to 400 SCCM.

8. The method for preparing copper-based multilayer graphene according to claim 1, characterized in that: The copper substrate is first annealed before growing the first layer of graphene; The annealing treatment step is: mounting the copper substrate on a graphite support, and then placing it in a CVD growth system, evacuating the vacuum, heating it to 980° C. to 1080° C., introducing the reducing gas, wherein the reducing gas flow rate is 800 SCCM, and the annealing time is ≥300 min; Preferably, the copper substrate is oxygen-free rolled copper foil; Preferably, the carbon source gas is one or a combination of methane, ethane and benzene.

9. The method for preparing copper-based multilayer graphene according to any one of claims 2, 3, 4, 5, 7 or 8, characterized in that: The reducing gas is specifically hydrogen.

10. A copper-based multilayer graphene, characterized in that: Prepared by the preparation method of copper-based multilayer graphene according to any one of claims 1 to 9.

Images