A two-dimensional graphene and its preparation method and application

Abstract

The present invention relates to the field of graphene technology, and specifically provides a two-dimensional graphene and a preparation method and application thereof. The preparation method of the two-dimensional graphene of the present invention comprises: (1) stretching two-dimensional graphene oxide to obtain an intermediate product; (2) reducing the intermediate product to obtain two-dimensional graphene. Compared with the prior art, the present invention constructs a wrinkle morphology on the surface of the two-dimensional graphene through stretching and reduction treatment, so that its conductive mode is transformed from a semiconductor type to a metal type, thereby increasing the metal abundance in the two-dimensional graphene, which is beneficial to its application in many fields such as the field of high-power electronic devices.

Description

Technical Field

[0001] The present invention relates to the technical field, and more specifically, to a two-dimensional graphene and a preparation method and application thereof. Background Art

[0002] Graphene is a sp 2 A new type of carbon material in which carbon atoms connected by orbital hybridization are stacked into a single-layer two-dimensional honeycomb lattice structure. Graphene has a unique "Dirac cone" type band structure, which makes its carrier mobility at room temperature as high as 1000cm 2 ·V -1 ·s. In addition, graphene has many excellent mechanical properties, such as light weight, flexibility, high strength, controllable morphology and negative Poisson's ratio, which provides a very promising alternative for the development of flexible semiconductor power devices. However, graphene's unique zero-gap Dirac cone band structure causes its carrier transport in the room temperature range to show typical semi-metallic characteristics, which makes graphene-based power semiconductor devices still rarely reported.

[0003] In past research, how to achieve controllable regulation of graphene band structure is one of the key issues in the field of graphene electrical transport research. Among them, the representative band structure regulation strategy is to geometrically design graphene at the nanoscale, such as cutting two-dimensional graphene into one-dimensional graphene nanoribbons. Under the action of mechanical cutting, the inherent in-plane isotropic topological morphology and chiral behavior of transport carriers of graphene are broken, which makes the graphene nanoribbons show semiconductor-type narrow band gap characteristics and the band gap size is closely related to the characteristic width of the graphene strip. Its internal mechanism can be attributed to the one-dimensional extended state formed by confined carriers at the boundary of the graphene strip. In recent years, the current modification strategy of graphene band structure is often achieved through doping, such as element doping represented by surface chemical functional group modification and local grain boundary component doping, and charge doping represented by double electric layer field effect doping and construction of symmetric superlattice configuration with zero energy mode. The above-mentioned means can regulate the band structure of graphene with mesoscopic characteristic size and realize the transition of carrier transport mode from semi-metal type to semiconductor type.

[0004] There are the following problems in regulating the band structure of graphene by introducing doping: a) doping elements can act as scattering centers to effectively scatter transport carriers, thereby significantly reducing the carrier mobility of the system, which greatly reduces its application prospects in the field of power electronic devices; b) current experimental doping methods are difficult to perform local processing on graphene, that is, it is difficult to effectively regulate the local carrier transport properties of graphene by introducing charge / element doping. How to achieve in-situ controllable regulation of graphene band structure / carrier transport properties and increase the metal abundance in two-dimensional graphene has significant scientific and application value. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a two-dimensional graphene and a preparation method and application thereof. The present invention constructs a wrinkled morphology on the surface of the two-dimensional graphene, so that its conductive mode is transformed from a semiconductor type to a metallic type, thereby increasing the metal abundance in the two-dimensional graphene, which is beneficial to its application in many fields such as the field of high-power electronic devices.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing two-dimensional graphene, comprising:

[0008] (1) stretching the two-dimensional graphene oxide to obtain an intermediate product;

[0009] (2) The intermediate product is reduced to obtain two-dimensional graphene.

[0010] The present invention has no special restrictions on the two-dimensional graphene oxide, and it can be prepared by conventional methods in the art. In one embodiment of the present invention, the resistivity of the two-dimensional graphene oxide is 0.30Ω·cm and the specific surface area is 1000m 2 ·g -1 .

[0011] In the present invention, the stretching is carried out in a reducing agent solution; the stretching is specifically: the intermediate product is sequentially wrapped and contacted with a stretching shaft;

[0012] The speed of the drawing shaft increases along the forward direction of the intermediate product; the number of the drawing shafts is ≥2, preferably 2. The present invention can directly affect the stress state inside the two-dimensional graphene oxide by adjusting the speed difference of the drawing shafts, plastically draw the two-dimensional graphene oxide, and then realize the regulation of the surface wrinkle morphology thereof.

[0013] In the present invention, the linear speed difference between two adjacent drafting axes is 0.01 to 0.02 rpm, preferably 0.01 rpm, and the drafting time is 5 to 20 s, preferably 5 s.

[0014] In one embodiment of the present invention, the intermediate product is sequentially wrapped with the first drafting shaft, the first transmission shaft, the second transmission shaft, and the second drafting shaft, the speed of the first drafting shaft is set to 0.05 rpm, the speed of the second drafting shaft is set to 0.06 rpm, the working time of the first drafting shaft and the second drafting shaft is 5s, and after the drafting is completed, it is maintained for 10s. The first transmission shaft and the second transmission shaft are transmission devices, and no mechanical driving force is applied.

[0015] In the present invention, the reduction treatment specifically comprises: mixing the intermediate product with a reducing agent solution, preferably immersing the intermediate product in the reducing agent solution; the mixing time is 1 to 5 minutes, preferably 3 minutes.

[0016] In the present invention, the reducing agent solution is obtained by mixing a reducing agent and a solvent; the solvent is an organic solvent; the molecular weight of the reducing agent is ≤500; the reducing agent is preferably hydrogen iodide; in one embodiment of the present invention, the reducing agent solution is a hydrogen iodide solution, which is obtained by mixing ethanol and hydrogen iodide; the volume ratio of ethanol to hydrogen iodide is 1:(1-4), preferably 1:3.

[0017] In the present invention, the method for preparing two-dimensional graphene further comprises: heat treating the intermediate product after the reduction treatment;

[0018] The temperature of the heat treatment is 2500-3500K, preferably 3000K; the time of the heat treatment is 3-5h, preferably 5h.

[0019] In the present invention, the mass ratio of the intermediate product to the reducing agent solution is 1:(1-80), preferably 1:50.

[0020] The two-dimensional graphene prepared by the present invention has a wrinkled morphology; in the two-dimensional graphene oxide, the ratio of the electrical conductivity of the wrinkled area to the electrical conductivity of the non-wrinkled area is (1.5-100):1, preferably 1.5:1.

[0021] The present invention also provides the use of the two-dimensional graphene prepared by the above two-dimensional graphene preparation method in preparing materials with metallic carrier characteristics.

[0022] The present invention provides a method for in-situ triggering a metallic carrier transport mode in two-dimensional graphene oxide. The method constructs more wrinkled morphologies of a "percolation network" configuration on the surface of the two-dimensional graphene through plastic stretching and reduction treatment, and the wrinkled morphology of the two-dimensional graphene surface can realize a metallic carrier transport mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1Schematic diagram of the plasticizing and stretching device of an embodiment of the present invention, wherein 1 is the first driving roller, 2 is the first transmission roller, 3 is the second transmission roller, 4 is the stretched sample, and 5 is the second driving roller. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In order to further illustrate the present invention, the following examples are used to describe the present invention in detail. The raw materials used in the following examples of the present invention are all commercially available products. The raw materials of the present invention were purchased from Beijing Deke Shimadzu Nanotechnology Co., Ltd.

[0026] Example 1

[0027] The method for preparing two-dimensional graphene in this embodiment adopts the following method: Figure 1 The drawing device shown in the figure prepares two-dimensional graphene, and the drawing device includes: a first driving roller 1, a first transmission roller 2, a second transmission roller 3, a drawn sample 4, and a second driving roller 5; wherein the first driving roller and the second driving roller are drawing axes, and the method of this embodiment includes the following steps:

[0028] (1) Load the two-dimensional graphene oxide into the driving roller device, and fix the connection position with double-sided tape, such as Figure 1 shown.

[0029] (2) Mechanical load stretching process: Drive roller 1 and drive roller 2 are turned on, and the speed difference between the two is 0.01 rpm (the speed of drive roller 1 is 0.05 rpm, and the speed of drive roller 2 is 0.06 rpm). The single working time of the drive roller is 5 s, and the mechanical state is maintained for 10 s after the drive roller is completed.

[0030] (3) The two-dimensional graphene oxide after plasticization and stretching treatment is subjected to liquid phase reduction treatment: the two-dimensional graphene oxide is placed in a mixed solution of anhydrous ethanol and hydrogen iodide for reduction treatment (the volume ratio of anhydrous ethanol and hydrogen iodide is 1:3), the mass ratio of the two-dimensional graphene oxide and the mixed solution is 1:50, and the liquid phase reduction treatment time is 3 minutes.

[0031] (4) The product after the liquid phase reduction treatment is subjected to high-temperature heat treatment at a temperature of 3000 K and a heat treatment time of 5 hours to obtain two-dimensional graphene.

[0032] The two-dimensional graphene obtained in this embodiment has a wrinkle morphology, the ratio of the electrical conductivity of the wrinkle area to the electrical conductivity of the non-wrinkle area is 1.5:1, the characteristic width of the wrinkle morphology is 5 nm, and the characteristic height is 5 nm.

[0033] Example 2

[0034] The method for preparing two-dimensional graphene in this embodiment uses the drawing device in Example 1 to prepare two-dimensional graphene, and specifically includes the following steps:

[0035] (1) Load the two-dimensional graphene oxide into the driving roller device, and fix the connection position with double-sided tape, such as Figure 1 shown.

[0036] (2) Mechanical load stretching process: Drive roller 1 and drive roller 2 are turned on, and the speed difference between the two is 0.01 rpm (the speed of drive roller 1 is 0.04 rpm, and the speed of drive roller 2 is 0.05 rpm). The single working time of the drive roller is 5 s, and the mechanical state is maintained for 10 s after the drive roller is completed.

[0037] (3) The two-dimensional graphene oxide after plasticization and stretching treatment is subjected to liquid phase reduction treatment: the two-dimensional graphene oxide is placed in a mixed solution of anhydrous ethanol and hydrogen iodide for reduction treatment (the volume ratio of anhydrous ethanol and hydrogen iodide is 1:3), the mass ratio of the two-dimensional graphene oxide and the mixed solution is 1:50, and the liquid phase reduction treatment time is 3 minutes.

[0038] (4) The product after the liquid phase reduction treatment is subjected to high-temperature heat treatment at a temperature of 3000 K and a heat treatment time of 5 hours to obtain two-dimensional graphene.

[0039] Example 3

[0040] The method for preparing two-dimensional graphene in this embodiment uses the drawing device in Example 1 to prepare two-dimensional graphene, and specifically includes the following steps:

[0041] (1) Load the two-dimensional graphene oxide into the driving roller device, and fix the connection position with double-sided tape, such as Figure 1 shown.

[0042] (2) Mechanical load stretching process: Turn on drive roller 1 and drive roller 2, and keep a speed difference of 0.01 rpm (the speed of drive roller 1 is 0.045 rpm, and the speed of drive roller 2 is 0.055 rpm). The single working time of the drive roller is 5 s, and the mechanical state is maintained for 10 s after the drive roller is completed.

[0043] (3) The two-dimensional graphene oxide after plasticization and stretching treatment is subjected to liquid phase reduction treatment: the two-dimensional graphene oxide is placed in a mixed solution of anhydrous ethanol and hydrogen iodide for reduction treatment (the volume ratio of anhydrous ethanol and hydrogen iodide is 1:3), the mass ratio of the two-dimensional graphene oxide and the mixed solution is 1:50, and the liquid phase reduction treatment time is 3 minutes.

[0044] (4) The product after the liquid phase reduction treatment is subjected to high-temperature heat treatment at a temperature of 3000 K and a heat treatment time of 5 hours to obtain two-dimensional graphene.

[0045] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing two-dimensional graphene, characterized in that: include: (1) Stretching the two-dimensional graphene oxide to obtain an intermediate product; (2) reducing the intermediate product to obtain two-dimensional graphene; The drawing is carried out in a reducing agent solution; The reducing agent solution is a hydrogen iodide solution, which is obtained by mixing ethanol and hydrogen iodide; the volume ratio of ethanol to hydrogen iodide is 1:(1-4); The drafting specifically comprises: wrapping the intermediate product around the drafting shaft in sequence; The speed of the drafting shaft increases along the advancing direction of the intermediate product; The number of drafting axes is ≥2; The linear speed difference between two adjacent drafting axes is 0.01~0.02 rpm; the drafting time is 5~20s; The reduction treatment specifically comprises: mixing the intermediate product with a reducing agent solution; The mixing time is 1 to 5 min; The method for preparing the two-dimensional graphene further comprises: heat treating the intermediate product after the reduction treatment; The temperature of the heat treatment is 2500~3500 K; The two-dimensional graphene has a wrinkled morphology; in the two-dimensional graphene, the ratio of the electrical conductivity of the wrinkled area to the electrical conductivity of the non-wrinkled area is (1.5~100):

1.

2. The method for preparing two-dimensional graphene according to claim 1, characterized in that: It is characterized in that The heat treatment time is 3 to 5 hours.

3. Use of the two-dimensional graphene prepared by the method for preparing the two-dimensional graphene according to claim 1 or 2 in preparing a material having metallic carrier characteristics.

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