Method for preparing multilayer graphene by using carbon source concentration gradient

Abstract

The invention relates to a method for preparing multilayer graphene by using carbon source concentration gradient. The method comprises the following steps: S1, placing a metal substrate capable of realizing double-sided carbon source concentration gradient in a chemical vapor deposition system; the method for realizing the double-sided carbon source concentration gradient comprises the following steps: carrying out single-sided packaging on a metal substrate; s2, a gaseous carbon source is introduced, a carbon source concentration difference is formed on the two faces of the metal substrate, and multiple layers of graphene grow. The method provided by the invention can be used for preparing thin-layer graphene with uniform growth layers.

Description

Technical Field

[0001] The present invention belongs to the field of carbon materials, and in particular relates to a method for preparing multilayer graphene by utilizing a carbon source concentration gradient. Background Art

[0002] Graphene is a sp 2 Graphene is a new material composed of tightly packed, hybrid-connected carbon atoms forming a single-layer, two-dimensional honeycomb lattice. This unique crystal structure possesses excellent optical, electrical, and mechanical properties, and holds significant promise for applications in materials science, micro-nanofabrication, energy, biomedicine, and drug delivery. It is considered a revolutionary material of the future. Graphene films are commonly produced by chemical vapor deposition (CVD).

[0003] Currently, the CVD method for preparing graphene thin films mainly uses metallic copper as a catalytic substrate to prepare catalytically grown large-area graphene. However, when graphene is grown on a metallic copper surface, it is difficult to grow large-area multilayer graphene due to the self-limiting effect. Currently, multilayer graphene is mainly grown by using the cooling precipitation mechanism of metallic nickel on a nickel surface with high carbon solubility. However, this method cannot control the amount of carbon precipitation and the uniformity of precipitation, and thus cannot produce uniform multilayer graphene. In addition, another method is to prepare multilayer graphene films by coating with a graphene powder solution, but this method produces relatively thick carbon films, and the graphene sheets that make up the carbon film are not continuous, resulting in relatively low performance. Therefore, how to prepare thinner graphene, especially multilayer graphene with a controllable thickness of less than 10nm, is a technical problem that urgently needs to be solved. The present invention solves this technical problem by utilizing a carbon source concentration gradient method to prepare multilayer graphene on the surface of a metal substrate with low solubility by regulating the carbon concentration gradient. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing multilayer graphene by utilizing a carbon source concentration gradient, so as to prepare multilayer uniform graphene.

[0005] The present invention provides a method for preparing multilayer graphene using a carbon source concentration gradient, comprising the following steps:

[0006] S1. A metal substrate having a double-sided carbon source concentration gradient is placed in a chemical vapor deposition system; the method for achieving a double-sided carbon source concentration gradient comprises encapsulating the metal substrate on one side;

[0007] S2. A gaseous carbon source is introduced to form a carbon source concentration difference on both sides of the metal substrate, thereby growing multilayer graphene.

[0008] Preferably, the metal substrate comprises any one of copper-nickel alloy or nickel.

[0009] More preferably, the metal substrate is a copper-nickel alloy.

[0010] Preferably, the single-sided encapsulation in step S1 is to encapsulate one side of the metal substrate with an insulating material; wherein the insulating material includes but is not limited to any one of sapphire, quartz, silicon, boron nitride or graphite.

[0011] Preferably, the gaseous carbon source in step S2 includes but is not limited to one or more of methane, ethylene, and acetylene.

[0012] Preferably, the growth temperature of the graphene in step S2 is 1000-1150°C.

[0013] More preferably, the growth temperature of the graphene is 1030-1070°C.

[0014] Preferably, the growth time of the graphene in step S2 is 10-240 min.

[0015] Preferably, the graphene has a thickness of 2-20 layers.

[0016] Beneficial effects

[0017] The method of the present invention can grow thin-layer graphene with a uniform number of layers, especially graphene with less than 20 layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a macroscopic image of multilayer graphene in Example 1 of the present invention.

[0019] Figure 2 This is a Raman spectrum of multilayer graphene in Example 1 of the present invention.

[0020] Figure 3 This is a test chart of the transmittance of multilayer graphene in Example 1 of the present invention.

[0021] Figure 4 This is an SEM image of multilayer graphene in Example 1 of the present invention.

[0022] Figure 5 This is a Raman spectrum of multilayer graphene in Example 2 of the present invention.

[0023] Figure 6 This is a TEM cross-sectional view of multilayer graphene in Example 2 of the present invention. DETAILED DESCRIPTION

[0024] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0025] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.

[0026] Example 1

[0027] The method for preparing multilayer graphene in this embodiment includes the following steps:

[0028] S1. A copper-nickel metal substrate encapsulated on one side of sapphire was selected as the metal substrate capable of achieving a double-sided carbon source concentration gradient. The substrate was cleaned with dilute hydrochloric acid, purified water, and isopropyl alcohol and then placed in a chemical vapor deposition system.

[0029] S2. Add methane and set the graphene growth temperature to 1050°C for 30 minutes.

[0030] S3. After peeling off the sapphire, 4 layers of graphene are obtained on the copper-nickel metal substrate.

[0031] Figure 1 This is a macroscopic photograph of multilayer graphene transferred onto quartz glass in this embodiment. The image shows that the graphene is relatively dark, indicating that the graphene has a large number of layers and is multilayer graphene. Figure 2 The Raman spectrum shows that graphene 2D (2700cm -1 ) peak ratio G(1600cm -1 ) peak is weak, which is multilayer graphene; Figure 3 is its light transmittance, indicating that it is multi-layer graphene; Figure 4 This is its SEM image, which shows that the graphene surface is clean and flat.

[0032] Example 2

[0033] The method for preparing multilayer graphene in this embodiment includes the following steps:

[0034] S1. A copper-nickel metal substrate encapsulated on one side of sapphire was selected as the metal substrate capable of achieving a double-sided carbon source concentration gradient. The substrate was cleaned with dilute hydrochloric acid, purified water, and isopropyl alcohol and then placed in a chemical vapor deposition system.

[0035] S2. Add methane and set the graphene growth temperature to 1200°C for 30 minutes;

[0036] S3. After peeling off the sapphire, 15 layers of graphene were obtained on the copper-nickel metal substrate.

[0037] Compared with Example 1, the growth temperature was changed to 1200°C.

[0038] Figure 5 is a Raman spectrum of the multilayer graphene obtained in this embodiment, wherein the graphene is multilayer graphene; Figure 6 This is its TEM cross-sectional view. It can be seen from the figure that the thickness of graphene is relatively thick and it is not a single-layer graphene.

[0039] Example 3

[0040] The method for preparing multilayer graphene in this embodiment includes the following steps:

[0041] S1. A copper-nickel metal substrate encapsulated on one side of sapphire was selected as the metal substrate capable of achieving a double-sided carbon source concentration gradient. The substrate was cleaned with dilute hydrochloric acid, purified water, and isopropyl alcohol and then placed in a chemical vapor deposition system.

[0042] S2. Add methane and set the graphene growth temperature to 1050°C for 240 min.

[0043] S3. After peeling off the sapphire, 20 layers of graphene were obtained on the copper-nickel metal substrate.

[0044] Compared with Example 1, the growth time was changed to 240 min.

[0045] Example 4

[0046] The method for preparing multilayer graphene in this embodiment includes the following steps:

[0047] S1. A copper-nickel metal substrate encapsulated on one side of sapphire was selected as the metal substrate capable of achieving a double-sided carbon source concentration gradient. The substrate was cleaned with dilute hydrochloric acid, purified water, and isopropyl alcohol and then placed in a chemical vapor deposition system.

[0048] S2. Add methane and set the graphene growth temperature to 1050°C for 10 minutes.

[0049] S3. After peeling off the sapphire, two layers of graphene are obtained on the copper-nickel metal substrate.

[0050] Compared with Example 1, the growth time was changed to 10 min.

[0051] Comparative Example 1

[0052] S1. A copper substrate encapsulated on one side of sapphire was selected as the metal substrate capable of achieving a double-sided carbon source concentration gradient. The substrate was cleaned with dilute hydrochloric acid, purified water, and isopropyl alcohol and then placed in a chemical vapor deposition system.

[0053] S2. Add methane and set the graphene growth temperature to 1050°C for 30 minutes.

[0054] S3. After peeling off the sapphire, no graphene grew on the copper metal substrate.

[0055] Compared with Example 1, the substrate is changed to a common copper substrate.

[0056] Comparative Example 2

[0057] S1. Select a copper-nickel metal substrate, clean it with dilute hydrochloric acid, purified water, and isopropyl alcohol, and then place it in a chemical vapor deposition system. The copper-nickel substrate material is not encapsulated, and both sides are directly exposed to the growth environment.

[0058] S2. Methane was introduced and the graphene growth temperature was set to 1050°C for 30 minutes to obtain a single-layer graphene on a copper-nickel metal substrate.

[0059] Compared with Example 1, no carbon source concentration difference is formed on both sides of the metal substrate.

[0060] The number of layers of graphene prepared in Examples 1 to 4 and Comparative Examples 1 to 2 is shown in Table 1. By comparing the number of graphene layers in Examples 1 to 4, it can be seen that the longer the graphene growth time, the thicker the layers; the higher the graphene growth temperature, the thicker the layers; in Comparative Example 2, no carbon source concentration difference is formed on both sides of the metal substrate, and the grown graphene is a single-layer graphene.

[0061] Table 1 Comparison of the number of graphene layers prepared in Examples 1 to 4 and Comparative Examples 1 to 2

[0062] sample Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Number of graphene layers 4 15 20 2 0 1

Claims

1. A method for preparing multilayer graphene using a carbon source concentration gradient, comprising the following steps: S1. A metal substrate having a double-sided carbon source concentration gradient is placed in a chemical vapor deposition system; the method for achieving a double-sided carbon source concentration gradient comprises encapsulating the metal substrate on one side; S2. A gaseous carbon source is introduced to form a carbon source concentration difference on both sides of the metal substrate, thereby growing multilayer graphene.

2. The method for preparing multilayer graphene using a carbon source concentration gradient according to claim 1, wherein: The metal substrate includes either copper-nickel alloy or nickel.

3. The method for preparing multilayer graphene using a carbon source concentration gradient according to claim 2, wherein: The metal substrate is a copper-nickel alloy.

4. The method for preparing multilayer graphene using a carbon source concentration gradient according to claim 1, wherein: The single-sided packaging is to use an insulating material to package one side of the metal substrate; wherein the insulating material includes any one of sapphire, quartz, silicon, boron nitride or graphite.

5. The method for preparing multilayer graphene using a carbon source concentration gradient according to claim 1, wherein: The gaseous carbon source in step S2 includes one or more of methane, ethylene, and acetylene.

6. The method for preparing multilayer graphene using a carbon source concentration gradient according to claim 1, wherein: The growth temperature of the graphene in step S2 is 1050-1200°C.

7. The method for preparing multilayer graphene using a carbon source concentration gradient according to claim 1, wherein: The growth time of the graphene in step S2 is 10-240 min.

8. The method for preparing multilayer graphene using a carbon source concentration gradient according to claim 1, wherein: The thickness of the graphene is 2-20 layers.

Images