CN115072711A

CN115072711A - Preparation method of graphene nanoribbon

Info

Publication number: CN115072711A
Application number: CN202110266957.0A
Authority: CN
Inventors: 史志文; 吕博赛; 陈佳俊; 娄硕
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2021-03-11
Filing date: 2021-03-11
Publication date: 2022-09-20
Anticipated expiration: 2041-03-11
Also published as: CN115072711B

Abstract

The invention provides a preparation method of a graphene nanoribbon, which is based on a catalytic chemical vapor deposition method for preparing the graphene nanoribbon, wherein a crystal material with an atomic-level flatness surface is used as a growth substrate, metal nanoparticles are used as a growth catalyst, and a carbon source gas containing carbon atoms is used as a growth gas, so that the graphene nanoribbon with micron-sized length and regular edge structure can be obtained.

Description

Preparation method of graphene nanoribbon

Technical Field

The invention belongs to the technical field of chemical material synthesis, and relates to a preparation method of a graphene nanoribbon.

Background

In recent years, graphene nanoribbons, which are one-dimensional materials, have attracted much attention. The special energy band structure of the graphene nanoribbon enables the graphene nanoribbon to have unique electrical, magnetic and optical properties. The graphene nanoribbon shows a huge application prospect in the fields of field effect transistors, gas sensing, photodetectors, energy storage and the like.

At present, there are two main types of methods for preparing graphene nanoribbons: the first is a top-down method, namely, large-area graphene is processed into a nanobelt by a micro-nano processing technology; the second method is a bottom-up method, that is, a surface chemical catalytic synthesis technology is adopted to catalytically polymerize small molecules containing benzene rings on the surface of noble metals into graphene nanoribbons. However, the former has the main problem that the processing precision is not enough, which leads to disorder of the edge structure of the prepared graphene nanoribbon, thereby losing the intrinsic property of the graphene nanoribbon; the main problem of the latter is that the preparation cost is high, the length of the prepared graphene nanoribbon is short, generally only dozens of nanometers, and the graphene nanoribbon with the size cannot be applied to devices, so that a preparation method of the graphene nanoribbon with high quality, large size and economy is lacked, the mass production of the graphene nanoribbon is realized, and the application of the graphene nanoribbon is greatly limited.

Therefore, it is necessary to provide a preparation method of graphene nanoribbons.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention is directed to a method for preparing graphene nanoribbons, which is used to solve the problem of the prior art that it is difficult to economically prepare graphene nanoribbons with high quality and large size.

In order to achieve the above objects and other related objects, the present invention provides a method for preparing graphene nanoribbons, comprising the steps of:

providing a substrate with atomic-scale flatness;

forming metal nano-catalyst particles on the substrate;

placing the substrate with the metal nano catalyst particles in a heating furnace for heating, and introducing carbon source gas to form a graphene nanoribbon on the substrate;

and closing the carbon source gas, and reducing the temperature to room temperature under the action of the protective gas.

Optionally, the substrate comprises a hexagonal boron nitride substrate or a graphite substrate.

Optionally, the metal nanocatalyst particles include one of iron metal nanocatalyst particles, cobalt metal nanocatalyst particles, nickel metal nanocatalyst particles, alloy nanocatalyst particles, and metal oxide nanocatalyst particles.

Optionally, the carbon source gas comprises one of methane, acetylene and ethanol.

Optionally, the step of forming the graphene nanoribbon on the substrate comprises:

providing a tubular furnace, and introducing hydrogen and carbon source gas into the tubular furnace;

and heating under the conditions of 1 standard atmospheric pressure, the temperature of 600-1000 ℃ and the heat preservation time of 20-40 min, so that the carbon source gas is cracked under the action of the metal nano catalyst particles to form carbon atoms, and the carbon atoms are separated out from the metal nano catalyst particles and grow to form the graphene nanoribbons on the substrate.

Optionally, the flow ratio of the hydrogen gas to the carbon source gas is 1: 5.

Optionally, the shielding gas comprises one or a combination of hydrogen, nitrogen, or an inert gas.

Optionally, the formed graphene nanoribbons have lengths that include a micron scale.

As described above, the method for preparing graphene nanoribbons according to the present invention is based on a catalytic chemical vapor deposition method for preparing graphene nanoribbons, wherein the method uses a crystal material having an atomically smooth surface as a growth substrate, uses metal nanoparticles as a growth catalyst, and uses a carbon source gas containing carbon atoms as a growth gas, so that graphene nanoribbons having a micron-sized length and a regular edge structure can be obtained.

Drawings

Fig. 1 is a schematic view of a process flow for preparing graphene nanoribbons according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of an apparatus for preparing graphene nanoribbons according to an embodiment of the present invention.

Fig. 3 shows an atomic force microscope picture of the graphene nanoribbon prepared in the example of the present invention.

Description of the element reference numerals

10-tube furnace

20 furnace tube

30 gas

100 substrate

200 metal nano catalyst particles

300 graphene nanoribbons

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

As in the detailed description of the embodiments of the present invention, the cross-sectional views illustrating the device structure are not partially enlarged in general scale for convenience of illustration, and the schematic views are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.

For convenience in description, spatial relational terms such as "below," "beneath," "below," "under," "over," "upper," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. As used herein, "between … …" is meant to include both endpoints.

In the context of this application, a structure described as a first feature being "on" a second feature may include embodiments where the first and second features are formed in direct contact, and may also include embodiments where additional features are formed in between the first and second features, such that the first and second features may not be in direct contact.

It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of each component in actual implementation may be changed freely, and the layout of the components may be more complicated.

As shown in fig. 1, the present embodiment provides a method for preparing a graphene nanoribbon, including the following steps:

providing a substrate with atomic level flatness;

forming metal nano-catalyst particles on the substrate;

The preparation method of the graphene nanoribbon is based on a catalytic chemical vapor deposition method, and the method adopts a crystal material with an atomic-level flatness surface as a growth substrate, adopts the metal nano-catalyst particles as a growth catalyst, and adopts the carbon source gas containing carbon atoms as a growth gas, so that the graphene nanoribbon with a micron-sized length and a neat edge structure can be obtained.

Referring to fig. 2 to 3, the steps for preparing the graphene nanoribbon are described below with reference to the accompanying drawings.

First, referring to fig. 2, a substrate 100 having atomic-scale flatness is provided.

As an example, the substrate 100 may include a hexagonal boron nitride substrate or a graphite substrate.

Specifically, the substrate 100 may adopt a composite substrate structure including a silicon wafer and the hexagonal boron nitride substrate or the graphite substrate located on the surface of the silicon wafer, but the structure of the substrate 100 is not limited thereto. The crystal material with the atomic-level flatness surface is used as a growth substrate, so that the formation of the graphene nanoribbon can be facilitated subsequently.

Next, a metal thin film (not shown) is formed on the substrate 100.

As an example, the metal thin film may include one of an iron metal thin film, a cobalt metal thin film, a nickel metal thin film, an alloy thin film, and a metal oxide thin film.

As an example, the method of forming the metal thin film may include one of an evaporation method, a spin coating method, and a dip coating method; the thickness of the metal thin film formed may be in the range of

Specifically, by preparing the metal thin film, iron metal, cobalt metal, and nickel metal may be formed on the surface of the substrate 100 to prepare for the subsequent preparation of the metal nano-catalyst particles, wherein the type of the metal thin film is not limited thereto, and when the type of the metal thin film is selected, the metal material needs to be a transition metal that can be co-melted with carbon. The method for forming the metal thin film may adopt an evaporation method, a spin coating method or a dip coating method, which is not limited herein, and the metal thin film may be formed in a thickness range

Such as

And the like.

Then, the first heating is performed in the heating furnace to form the metal nano catalyst particles 200.

As an example, the step of forming the metal nano-catalyst particles 200 may include:

providing a tubular furnace 10, and introducing hydrogen and argon into the tubular furnace 10;

under 1 standard atmosphere, raising the temperature from the room temperature to 600-800 ℃, wherein the time for raising the temperature comprises 10-20 min, and carrying out first heating to enable the metal film to agglomerate so as to form the metal nano catalyst particles 200 on the substrate 100.

Specifically, referring to fig. 2, the heating furnace provided in this embodiment employs the tube furnace 10 with the furnace tube 20, so as to provide a heating furnace having good sealing performance, thermal insulation box and temperature control stability, but the selection of the type of the heating furnace is not limited thereto. When the substrate 100 having the metal particles on the surface is placed in the furnace tube 20 and the first heating is performed, the metal particles may be agglomerated, and the metal nano-catalyst particles 200 having a certain size are formed on the substrate 100. In this embodiment, before the first heating, it is preferable to introduce gas 30, such as hydrogen and argon, into the tube furnace 10 so as to discharge impurity gases, such as oxygen, in the furnace tube 20, that is, the argon may be used as a protective gas, and the introduced hydrogen may be used as a protective gas and may also be used as a reducing gas so as to reduce some carbon-containing impurity substances generated by the carbon source in the subsequent high-temperature heating process. In this embodiment, the temperature is raised from the chamber to 600-800 ℃, such as 600 ℃, 700 ℃, 800 ℃ and the like, under 1 standard atmosphere, and the temperature raising time may include 10 min-20 min, such as 10min, 15min, 20min and the like, and the heating process parameters related to the first heating are not limited herein. The flow ratio of the hydrogen gas to the argon gas can be 2:1, for example, the flow of the hydrogen gas can be 40SCCM, the flow of the argon gas can be 20SCCM, and the specific flow can be set as required and is not limited herein.

Then, a carbon source gas is introduced into the heating furnace and a second heating is performed, so that the graphene nanoribbon 300 is formed on the substrate 100.

As an example, the carbon source gas includes one of methane, acetylene, and ethanol.

As an example, the step of forming the graphene nanoribbon on the substrate 100 includes:

providing a tubular furnace 10, and introducing hydrogen and carbon source gas into the tubular furnace 10;

and under 1 standard atmosphere, the temperature is 600-1000 ℃, the heat preservation time is 20-40 min, second heating is carried out, the carbon source gas is cracked under the action of the metal nano catalyst particles to form carbon atoms, and the carbon atoms are separated out from the metal nano catalyst particles to grow so as to form the graphene nanoribbon 300 on the substrate 100.

Specifically, during the second heating, the gas 30 introduced into the furnace tube 20 may include the carbon source gas, such as methane, acetylene, or ethanol, at a high temperature of 600 ℃ to 1000 ℃, such as 600 ℃, 800 ℃, 1000 ℃, etc., so as to crack the carbon source gas and obtain carbon atoms therefrom under the catalytic assistance of the metal nano-catalytic particles 200, and when the carbon concentration in the metal nano-catalytic particles 200 reaches saturation, carbon is precipitated from the surface of the metal nano-catalytic particles 200, so as to grow the graphene nanoribbon 300, as shown in fig. 3. In this embodiment, the same tubular furnace 10 may be used for the second heating and the first heating, and when the high-temperature heating is performed, the gas 30 in the furnace tube 20 may further include the continuously introduced hydrogen gas in addition to the introduced carbon source gas, so as to reduce some carbon-containing impurities generated by the carbon source gas at a high temperature through the hydrogen gas. The flow ratio of the hydrogen gas to the carbon source gas may be 1:5, for example, the flow of the hydrogen gas may be 40SCCM, the flow of the carbon source gas may be 200SCCM, and the specific flow may be set as needed and is not limited herein.

As an example, the length of the formed graphene nanoribbon 300 may include a micrometer scale.

Specifically, referring to fig. 3, in the embodiment, the graphene nanoribbon 300 is prepared based on a catalytic chemical vapor deposition method, the graphene nanoribbon 300 with micron-scale length and regular edge structure can be prepared, and the method is simple to operate, low in cost and capable of realizing large-scale production.

And then, closing the carbon source gas, and reducing the temperature to the room temperature under the action of the protective gas.

By way of example, the shielding gas may include one or a combination of hydrogen, nitrogen, or an inert gas.

Specifically, in this embodiment, the hydrogen gas is used as the protective gas to avoid the influence of the external gas on the temperature reduction process of the graphene nanoribbon 300 due to the sealing property of the tube furnace 10 after the carbon source gas is turned off, so as to prepare the high-quality graphene nanoribbon 300, but the type of the protective gas is not limited thereto.

The following examples further illustrate the preparation of the graphene nanoribbon of the present invention, including:

example one

1) A silicon wafer having an oxide layer of 300nm in thickness on the surface thereof was taken and cut into 1cm X1 cm pieces.

2) Hexagonal Boron Nitride (HBN) flakes were prepared on the above silicon wafer by a mechanical lift-off method as a base material for growth.

3) Evaporating on the substrate material by electron beam evaporation

A nickel metal thin film of thickness, as a catalyst for growth.

4) The substrate coated with the catalyst is placed in a tube furnace, two gases of hydrogen (flow rate of 40SCCM) and argon (flow rate of 20SCCM) are introduced, the temperature is gradually increased to 800 ℃ from room temperature, the temperature rising process is about 15min, and the air pressure is kept at 1 standard atmospheric pressure in the temperature rising process.

5) When the temperature reaches 800 ℃, stopping introducing the argon, introducing 200SCCM methane gas as growth gas on the basis that the original hydrogen flow, namely the flow is 40SCCM, and growing at 800 ℃ for 30min, wherein the pressure is kept at 1 standard atmospheric pressure in the growth process.

6) And after the growth is finished, closing the methane gas, naturally cooling to room temperature, and then taking out the sample to obtain the graphene nanoribbon.

Example two

1) A piece of highly oriented pyrolytic graphite was taken, the size of which was about 1cm by 1 cm.

2) Evaporating on the substrate material by electron beam evaporation

A thick iron metal film as a catalyst for growth.

3) Placing the substrate coated with the catalyst in a tube furnace, gradually increasing the temperature from room temperature to 800 ℃ under the environment of introducing two protective gases of hydrogen (flow rate 40SCCM) and argon (flow rate 20SCCM), wherein the temperature increasing process is about 15min, and the air pressure is kept at 1 standard atmospheric pressure in the temperature increasing process.

4) When the temperature reaches 800 ℃, stopping introducing the argon, introducing 200SCCM methane gas as growth gas on the basis that the original hydrogen flow, namely the flow is 40SCCM, and growing at 800 ℃ for 30min, wherein the pressure is kept at 1 standard atmospheric pressure in the growth process.

5) And after the growth is finished, closing the methane gas, naturally cooling to room temperature, and then taking out the sample to obtain the graphene nanoribbon.

In summary, the present invention provides a method for preparing graphene nanoribbons based on a catalytic chemical vapor deposition method, wherein the method employs a crystal material with an atomic-level flatness surface as a growth substrate, employs metal nanoparticles as a growth catalyst, and employs a carbon source gas containing carbon atoms as a growth gas, so as to obtain graphene nanoribbons with micron-sized lengths and regular edge structures.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A preparation method of a graphene nanoribbon is characterized by comprising the following steps:

providing a substrate with atomic-scale flatness;

forming metal nano-catalyst particles on the substrate;

2. The method for preparing graphene nanoribbons according to claim 1, wherein: the substrate comprises a hexagonal boron nitride substrate or a graphite substrate.

3. The method for preparing graphene nanoribbons according to claim 1, wherein: the metal nano-catalyst particles comprise one of iron metal nano-catalyst particles, cobalt metal nano-catalyst particles, nickel metal nano-catalyst particles, alloy nano-catalyst particles and metal oxide nano-catalyst particles.

4. The method for preparing graphene nanoribbons according to claim 1, wherein: the carbon source gas comprises one of methane, acetylene and ethanol.

5. The method of preparing graphene nanoribbons according to claim 1, wherein the step of forming the graphene nanoribbons on the substrate comprises:

6. The method for preparing graphene nanoribbons according to claim 5, wherein: the flow ratio of the hydrogen gas to the carbon source gas is 1: 5.

7. The method for preparing graphene nanoribbons according to claim 1, wherein: the protective gas comprises one or a combination of hydrogen, nitrogen or inert gases.

8. The method for preparing graphene nanoribbons according to claim 1, wherein: the length of the formed graphene nanoribbon includes a micrometer scale.