CN104843681A - Macroscopic quantity preparation method of dimension-ontrollable graphene quantum dots - Google Patents

Abstract

The invention discloses a method for mass-preparing graphene quantum dots with a controllable size, comprising the following steps: a. depositing a catalyst metal thin film on a substrate; b. Etching the metal film to make a nano-scale patterned metal catalyst; c. placing the substrate in a chemical vapor deposition reaction chamber, and feeding a carbon source and a reducing gas at a high temperature to make graphene quantum dots on the nano-metal catalyst; d. Cool to room temperature in a reducing atmosphere, take out the substrate and place it in a nano metal etching solution to obtain quantum dots suspended in the solution. The invention uses CVD method to prepare graphene quantum dots, realizes the macro-preparation of quantum dots; adopts etching process to obtain nanoscale patterned metal as a catalyst, realizes the precise and controllable size of graphene quantum dots by controlling the size of the catalyst, and improves Increased productivity and reduced costs.

Description

Macrofabrication method of graphene quantum dots with controllable size

technical field

The invention relates to a method for preparing graphene, in particular to a method for preparing graphene quantum dots, which is applied in the technical field of quantum dot synthesis.

Background technique

Graphene quantum dot (Graphene quantum dot) is a quasi-zero-dimensional nanomaterial, and the movement of electrons in it is restricted in all directions, so the quantum confinement effect is particularly significant and has many unique properties. Graphene quantum dots have important potential applications in the fields of biology, medicine, materials, and new semiconductor devices. It can realize single-molecule sensors, and it may also lead to ultra-small transistors or on-chip communication using semiconductor lasers to make chemical sensors, solar cells, medical imaging devices, or nanoscale circuits.

The synthesis methods of graphene quantum dots are mainly divided into two categories: top-down and bottom-up methods. The bottom-up method is to cut large-size graphene flakes into small-size graphene quantum dots by physical or chemical methods, including hydrothermal method, electrochemical method and chemical method to strip carbon fibers; bottom-up The most common method is to use small molecules as precursors to prepare graphene quantum dots through a series of chemical reactions, mainly including ultrasonic method, microwave method, and solution chemical method. Other more special methods, such as electron beam etching and ruthenium-catalyzed fullerene cage opening method, require harsh preparation conditions to a large extent, which limits the promotion of these methods. Therefore, it is imminent to find a simple method for the mass preparation of graphene quantum dots.

Contents of the invention

In order to solve the problems of the prior art, the purpose of the present invention is to overcome the deficiencies of the prior art, to provide a method for the macro preparation of graphene quantum dots with a controllable size, and to realize the preparation of nano-patterned metal catalysts by etching commonly used in the industry , using the classic CVD method to prepare graphene quantum dots, the preparation process is simple and easy, and the size of graphene quantum dots can be controlled by adjusting the pattern size, which improves the yield and reduces the cost.

In order to achieve the above invention creation purpose, the present invention adopts the following technical solutions:

A method for mass-preparing graphene quantum dots with a controllable size, comprising the steps of:

a. Deposit a metal catalyst on a clean substrate to prepare a metal film, and the thickness of the metal film is less than 50 nanometers; the metal catalyst is preferably any metal or any metal alloy nanoparticles in copper, nickel, platinum and gold; preparation The deposition method of the metal thin film is preferably thermal evaporation, magnetron sputtering or electron beam evaporation; the substrate is preferably sapphire, silicon wafer GaN epitaxial wafer, silicon wafer, glass wafer, aluminum oxide wafer, indium tin oxide wafer , Fluorine-doped zinc oxide sheet or flexible substrate;

b. Etching the metal thin film prepared in the step a to obtain nanoscale patterned metal catalyst particles, the characteristic size of the obtained patterned metal catalyst particles is less than 60nm; the prepared nanoscale patterned metal catalyst particles The shape is preferably any one or a combination of cylinders, cubes, cuboids, tetrahedrons, frustums and frustums;

c. The substrate is placed in a chemical vapor deposition reaction chamber, and a carbon source and a reducing gas are introduced at 300-1100 ° C. The nano-metal catalyst particles prepared in the step b are supported to generate graphene quantum dots, and the controlled The prepared graphene quantum dot has 1-3 layers of monoatomic graphite layer; the carbon source adopts gaseous carbon source, specifically preferably methane, acetylene or ethylene; or the carbon source adopts solid carbon source, specifically preferably adopts urea, grass or biscuit ; Or the carbon source is at least preferably a stupid liquid carbon source; the chemical vapor deposition system preferably adopts a thermal CVD furnace, a PECVD furnace or a microwave-assisted CVD furnace; the chemical vapor deposition system preferably also includes a preheating furnace;

d. The substrate attached to generate graphene quantum dots prepared in the step c is cooled to room temperature in a reducing atmosphere, and the substrate is taken out and placed in a nanometer metal etching solution, so that after the metal catalyst particles are completely dissolved, the graphite Graphene quantum dots are separated from the substrate to obtain graphene quantum dots suspended in the solution, and then after separation and purification, graphene quantum dots are obtained; the etching solution is preferably hydrochloric acid, sulfuric acid, iron nitrate, ammonium persulfate, hydrogen Any one of hydrofluoric acid, glacial acetic acid and nitric acid or a mixture of any one, the etching process is one or more etchings.

Compared with the prior art, the present invention has the following obvious outstanding substantive features and significant advantages:

1. The present invention controls the size of graphene quantum dots by controlling the characteristic size of the nanoscale patterned metal catalyst, which is simple and controllable;

2. The present invention adopts CVD method to realize the macro-preparation of graphene quantum dots, with high yield and low cost;

3. The present invention adopts the commonly used etching process, the process is simple and easy to implement, and it is easy to promote, and there is room for further size adjustment with the development of etching technology.

Description of drawings

Fig. 1 is a flow chart of the mass production method of graphene quantum dots with controllable size in the preferred embodiment of the present invention.

Detailed ways

Preferred embodiments of the present invention are described in detail as follows:

In the present embodiment, referring to Fig. 1, the macro-preparation method of graphene quantum dots with controllable size comprises the following steps:

a. Deposit 20nm thick copper on the cleaned silicon wafer by thermal evaporation;

b. Etching the copper film to realize the preparation of patterned copper with a pitch of 30nm and a size of 30*30nm;

c. Place the substrate obtained in step b in a PECVD furnace, evacuate until the pressure in the reaction chamber drops below 0.1 Pascal, feed methane at a flow rate of 10 sccm, hydrogen at 10 sccm, heat up to 500°C, and keep the temperature at 200 Pascal for 10 minutes. Cut off methane and cool to room temperature under the condition of constant hydrogen flow;

d. Take out the combination of silicon wafer/copper/graphene quantum dots obtained in step c, place it in a ferric nitrate solution with a concentration of 0.1g/ml, and after the metal catalyst copper is completely dissolved, separate and purify to complete the preparation of graphene quantum dots .

In this example, nano-nickel powder is used as the catalyst for the macro-preparation of graphene quantum dots, and the nano-scale patterned catalyst obtained by etching the metal film is used to realize the simple macro-preparation of graphene quantum dots at low temperature through PECVD. The etching process is used to obtain nanoscale patterned metal as a catalyst, and the precise controllable size of graphene quantum dots is realized by controlling the size of the catalyst.

The embodiments of the present invention have been described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, and various changes can also be made according to the purpose of the invention of the present invention. The changes, modifications, substitutions, combinations, and simplifications should be equivalent replacement methods, as long as they meet the purpose of the invention, as long as they do not deviate from the technical principles and inventions of the method for mass production of graphene quantum dots with controllable sizes Design, all belong to the protection scope of the present invention.

Claims (9)

1. a macro preparation method of controllable size graphene quantum dots, is characterized in that, comprises the steps: a. Deposit a metal catalyst on a clean substrate to prepare a metal film, and the thickness of the metal film is less than 50 nanometers; b. Etching the metal thin film prepared in the step a to obtain nanoscale patterned metal catalyst particles, the characteristic size of the patterned metal catalyst particles is less than 60nm; c. The substrate is placed in a chemical vapor deposition reaction chamber, and a carbon source and a reducing gas are introduced at 300-1100 ° C. The nano-metal catalyst particles prepared in the step b are supported to generate graphene quantum dots, and the controlled The prepared graphene quantum dots have 1-3 single-atom graphite layers; d. The substrate attached to generate graphene quantum dots prepared in the step c is cooled to room temperature in a reducing atmosphere, and the substrate is taken out and placed in a nanometer metal etching solution, so that after the metal catalyst particles are completely dissolved, the graphite The graphene quantum dots are separated from the substrate to obtain the graphene quantum dots suspended in the solution, and then the graphene quantum dots are obtained after separation and purification. 2. according to the macro-preparation method of the described controllable size graphene quantum dot of claim 1, it is characterized in that: in described step b, the shape of the described nanoscale patterned metal catalyst particle of preparation is cylinder, cube , cuboid, tetrahedron, truncated prism and truncated cone, or any combination thereof. 3. according to the macro-preparation method of the described controllable size graphene quantum dot of claim 1 or 2, it is characterized in that: in described step a, described metal catalyst adopts any one in copper, nickel, platinum and gold alloy nanoparticles of a single metal or any several metals. 4. according to the macro preparation method of the described controllable size graphene quantum dot of claim 1 or 2, it is characterized in that: in described step a, the deposition method of preparing described metal thin film is thermal evaporation, magnetron sputtering or electron beam evaporation method. 5. according to the macro-preparation method of the described controllable size graphene quantum dot of claim 1 or 2, it is characterized in that: in described step a, described substrate is sapphire, silicon wafer GaN epitaxial wafer, silicon wafer, Glass sheet, aluminum oxide sheet, indium tin oxide sheet, fluorine-doped zinc oxide sheet or flexible substrate. 6. according to the macro preparation method of the described controllable size graphene quantum dot of claim 1 or 2, it is characterized in that: in described step c, described carbon source adopts gaseous carbon source, specifically adopts methane, acetylene or ethylene or the carbon source is a solid carbon source, specifically urea, grass or biscuit; or the carbon source is at least a stupid liquid carbon source. 7. according to the macro-preparation method of the described controllable size graphene quantum dot of claim 1 or 2, it is characterized in that: in described step c, chemical vapor deposition system adopts thermal CVD furnace, PECVD furnace or microwave-assisted CVD furnace . 8. The method for mass production of graphene quantum dots with controllable size according to claim 7, characterized in that: the chemical vapor deposition system also includes a preheating furnace. 9. according to the macro preparation method of the described controllable size graphene quantum dot of claim 1 or 2, it is characterized in that: in described step d, etching solution adopts hydrochloric acid, sulfuric acid, ferric nitrate, ammonium persulfate, hydrogen Any one of hydrofluoric acid, glacial acetic acid and nitric acid or a mixture of any one, the etching process is one or more etchings.