A continuous chemical vapor deposition method for preparing high-purity single-layer graphene

Abstract

The present application relates to the technical field of sleeper manufacturing, and discloses a continuous chemical vapor deposition preparation method of high-purity single-layer graphene, which comprises the following steps: a) using methane as a carbon source precursor gas, and mixing the methane with hydrogen gas at a volume ratio of 1:15 to form a mixed gas; b) adding 0.05% of tungsten hexafluoride as an auxiliary catalyst in the mixed gas; c) introducing the mixed gas above a pretreated copper substrate material; and d) performing a chemical vapor deposition reaction at a constant temperature of 1000 DEG C and under a pressure condition of 150 Pa to form single-layer graphene; the present application improves the uniformity and quality of the graphene film. The trace amount of tungsten hexafluoride added as an auxiliary catalyst optimizes the growth conditions of the graphene, the residues on the substrate are completely removed through the alternate cleaning of ultrapure water and isopropyl alcohol and the drying by nitrogen blowing, the occurrence of oxidation is prevented, and the purity of the product is improved.

Description

Technical Field

[0001] This invention relates to the field of railway sleeper manufacturing technology, specifically to a continuous chemical vapor deposition method for preparing high-purity monolayer graphene. Background Technology

[0002] Graphene, as a two-dimensional material with excellent electrical, optical, and mechanical properties, has shown great application potential in many fields. However, the preparation of high-quality, large-scale graphene remains a challenge. Chemical vapor deposition (CVD) has attracted widespread attention due to its ability to prepare large-area, high-quality graphene. However, traditional CVD methods suffer from slow growth rates and poor film uniformity, limiting their application in practical production.

[0003] Existing CVD methods for preparing graphene typically face the following problems:

[0004] In traditional CVD methods, the growth rate of graphene is low due to limitations in growth conditions, resulting in low production efficiency. During the growth process, defects in the grown graphene film can occur due to uneven gas distribution or improper temperature control, affecting the uniformity and quality of the film. Furthermore, the adhesion between graphene and the substrate is weak, making it prone to damage during transfer and reducing the yield. Summary of the Invention

[0005] The purpose of this invention is to provide a continuous chemical vapor deposition method for preparing high-purity monolayer graphene, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A continuous chemical vapor deposition method for preparing high-purity monolayer graphene includes the following steps:

[0008] a) Use methane as a carbon source precursor gas and mix it with hydrogen at a volume ratio of 1:15 to form a mixed gas.

[0009] b) Add 0.05% by weight of tungsten hexafluoride as an auxiliary catalyst to the mixed gas;

[0010] c) Introduce the mixed gas over the pretreated copper substrate material;

[0011] d) At a constant temperature of 1000℃ and a pressure of 150Pa, a chemical vapor deposition reaction was carried out to form a single layer of graphene.

[0012] e) After growth is complete, the substrate is rinsed alternately with ultrapure water and isopropanol, and then purged with nitrogen to dry, removing any residues and obtaining a high-purity monolayer graphene product.

[0013] By controlling gas flow rate, temperature, and pressure, large-scale continuous production of monolayer graphene was achieved, ensuring the high purity and uniformity of the product.

[0014] Preferably, the total flow rate of the mixed gas is 100 sccm and remains constant throughout the deposition process to ensure uniform gas distribution.

[0015] Preferably, the substrate material is pretreated by ultrasonic cleaning and plasma treatment before use to improve the cleanliness and activity of the substrate surface;

[0016] The plasma treatment is performed using argon gas for 10 minutes at a power of 100W.

[0017] Preferably, the chemical vapor deposition reaction is carried out in a reaction chamber equipped with a temperature gradient control device to achieve uniform distribution of graphene.

[0018] The inner wall of the reaction chamber is made of high-temperature resistant material and is equipped with multiple temperature sensors to monitor temperature changes.

[0019] Preferably, the substrate material is preheated before the chemical vapor deposition reaction at a temperature of 250°C for 20 minutes to reduce the oxide layer on the substrate surface and to achieve uniform heating by means of an infrared heater.

[0020] Preferably, the rinsing step further includes rinsing in ultrapure water for 5 minutes using an ultrasonic cleaner, followed by rinsing in isopropanol for 5 minutes, and purging and drying with nitrogen gas after each rinse to thoroughly remove residues and prevent oxidation.

[0021] Preferably, the method further includes using an automated control system to monitor and adjust the gas flow rate, temperature, and pressure during the chemical vapor deposition reaction in real time to ensure uniform growth of monolayer graphene, and monitoring the quality of graphene in real time through an online quality inspection system, wherein the automated control system includes a PLC controller and a PID algorithm.

[0022] Preferably, the substrate material undergoes surface modification treatment before use to enhance the adhesion between graphene and the substrate, specifically by depositing a nickel transition metal layer with a thickness of 1 nm on the substrate surface.

[0023] Preferably, the method further includes characterizing the obtained graphene by Raman spectroscopy after growth to ensure that it is a monolayer without obvious defects, and confirming its chemical composition and purity by X-ray photoelectron spectroscopy.

[0024] The Raman spectroscopy analysis used a 532 nm laser excitation with a resolution of 1 cm⁻¹; the X-ray photoelectron spectroscopy analysis used an AlKα X-ray source with an energy resolution of less than 0.5 eV.

[0025] Preferably, the spring three allows the sealing plate to be pushed open after closing, thereby allowing the release agent to continue spraying.

[0026] The present invention has at least the following beneficial effects:

[0027] (1) This scheme ensures the effective utilization of the carbon source by controlling the ratio of methane to hydrogen (1:15), thereby improving the uniformity and quality of the graphene film. Adding trace amounts of tungsten hexafluoride as an auxiliary catalyst optimizes the graphene growth conditions, further enhancing the film quality. A combination of ultrasonic cleaning and plasma treatment effectively removes contaminants and impurities from the copper foil surface, increasing the active sites on the substrate surface and promoting uniform graphene growth. Alternating cleaning with ultrapure water and isopropanol, followed by nitrogen purging and drying, thoroughly removes residues from the substrate, preventing oxidation and improving product purity. Raman spectroscopy and X-ray photoelectron spectroscopy analysis of the grown graphene ensures it is a single layer without significant defects and confirms its chemical composition and purity.

[0028] (2) This scheme significantly improves the graphene growth rate by increasing the total flow rate of the mixed gas to 120 sccm, thereby accelerating the supply of carbon source. Considering the increased flow rate, the actual amount of tungsten hexafluoride added was adjusted to maintain a consistent concentration and optimize growth conditions. The nitrogen purging time was increased to ensure the substrate was completely dry, avoiding the influence of residual moisture on the graphene. A compensation mechanism for flow rate changes was added to the automated control system to adapt to temperature and pressure control at higher flow rates, ensuring consistent growth conditions.

[0029] (3) This method significantly enhances the adhesion between graphene and the substrate by depositing a 2nm thick titanium dioxide film on the substrate surface, thereby improving the integrity and stability during the transfer process. Monitoring the changes in the substrate surface state during the deposition process ensures that the ALD layer does not affect the growth of graphene, thus guaranteeing the quality of the final product. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] Please see Figure 1 This invention provides a technical solution: a continuous chemical vapor deposition method for preparing high-purity monolayer graphene, comprising the following steps:

[0035] Step a) First, methane is selected as the carbon source precursor gas and mixed with hydrogen at a volume ratio of 1:15 to form a mixed gas. The ratio of the mixed gas is crucial for the uniformity and quality of the subsequent graphene film.

[0036] Step b) Add 0.05% by weight of tungsten hexafluoride as an auxiliary catalyst to the mixed gas formed in step a). Tungsten hexafluoride was chosen to optimize the growth conditions of the graphene film and improve the quality of the film.

[0037] Step c) High-purity copper foil with a thickness of approximately 25 μm is selected as the substrate material. Before use, the copper foil needs to be cleaned in acetone, isopropanol, and ultrapure water for at least 5 minutes each using an ultrasonic cleaner to remove surface oil and particulate matter. Subsequently, the cleaned copper foil is placed in a plasma cleaning device and treated with argon plasma at a power of 100W for 10 minutes. Plasma treatment can activate the copper foil surface, increase surface active sites, and facilitate subsequent graphene growth.

[0038] Step d) The substrate material needs to be preheated before the mixed gas is introduced. The preheating temperature is 250°C and the time is 20 minutes. Preheating can be achieved by an infrared heater. The purpose is to reduce the oxide layer on the substrate surface and ensure the smooth progress of the subsequent deposition process.

[0039] Step e) The preheated copper foil is transferred to the chemical vapor deposition reaction chamber. The chamber walls must be made of high-temperature-resistant materials (such as quartz or high-temperature alloys). A temperature gradient control device is installed within the reaction chamber to maintain a constant temperature of 1000°C. The pressure within the reaction chamber is maintained at approximately 150 Pa, adjustable via a vacuum pump and gas inlet. The total flow rate of the mixed gas is controlled at 100 sccm and kept constant using a mass flow controller (MFC) to ensure uniform gas distribution. During the reaction, the substrate material is rotated uniformly at 60 revolutions per minute on a rotary table to promote uniform growth of the graphene film.

[0040] Step f) In order to further promote the uniform growth of graphene and ensure the uniform distribution of graphene layers, the substrate material is rotated at a speed of 60 revolutions per minute by a rotary table during the reaction process.

[0041] After step g) growth is completed, the substrate is cleaned alternately with ultrapure water and isopropanol. The substrate is then cleaned with an ultrasonic cleaner for 5 minutes in ultrapure water, followed by 5 minutes in isopropanol. After each cleaning, the substrate is purged with nitrogen to dry it, so as to thoroughly remove any residues and prevent oxidation.

[0042] In step h), throughout the entire chemical vapor deposition process, gas flow rate, temperature, and pressure are monitored and adjusted in real time by an automated control system (including a PLC controller and a PID algorithm) to ensure uniform growth of monolayer graphene. Simultaneously, the quality of the graphene is monitored in real time through an online quality inspection system.

[0043] PID stands for "Proportional-Integral-Derivative Controller". A PID controller is a commonly used feedback controller widely applied in industrial automation control systems. The PID algorithm calculates the system's error signal (the difference between the setpoint and the actual measured value) and adjusts the control input based on this error to reduce or eliminate the error.

[0044] Step i) In order to enhance the adhesion between graphene and the substrate, the substrate material is also subjected to surface modification treatment before use, that is, a nickel transition metal layer with a thickness of 1nm is deposited on the substrate surface.

[0045] Step j) Finally, the obtained graphene was characterized by Raman spectroscopy (using a 532 nm laser excitation with a resolution of 1 cm⁻¹) and X-ray photoelectron spectroscopy (using an AlKα X-ray source with an energy resolution of less than 0.5 eV) to ensure that it was a monolayer without obvious defects and to confirm its chemical composition and purity.

[0046] Example 2

[0047] This embodiment protects a continuous chemical vapor deposition method for preparing high-purity monolayer graphene, used to improve the growth rate:

[0048] This embodiment aims to improve the growth rate of graphene by adjusting the reaction conditions without sacrificing its purity and uniformity, and includes the following steps:

[0049] Step a) Use the same methane and hydrogen ratio as in Example 1, but increase the total flow rate to 120 sccm to accelerate the supply of carbon source.

[0050] Step b) The amount of tungsten hexafluoride added as an auxiliary catalyst remains unchanged, but considering the increase in flow rate, the actual amount of tungsten hexafluoride added needs to be adjusted by calculation to maintain the consistency of its concentration.

[0051] Step c) uses the same pretreatment method as in Example 1, but increases the plasma treatment time to 15 minutes to further improve the cleanliness of the substrate surface.

[0052] Step d) Increase the preheating temperature to 300°C to accelerate the decomposition of the oxide layer on the substrate surface, and the time remains 20 minutes.

[0053] Step e) The reaction temperature is increased to 1050°C to promote a faster chemical reaction rate, while maintaining the pressure condition of 150 Pa.

[0054] Step f) The rinsing procedure is the same as in Example 1, but the nitrogen purging time is increased to ensure that the substrate is completely dry.

[0055] Step g) Add a compensation mechanism for flow rate changes to the automated control system to adapt to temperature and pressure control at higher flow rates.

[0056] Step h) uses Raman spectroscopy and X-ray photoelectron spectroscopy to confirm whether the quality of graphene is affected by the increased growth rate.

[0057] Example 3

[0058] This embodiment protects a continuous chemical vapor deposition method for preparing high-purity monolayer graphene, used to enhance the adhesion between graphene and a substrate:

[0059] This embodiment aims to enhance the adhesion between graphene and a copper substrate by changing the substrate surface treatment method, thereby improving the integrity and stability during the transfer process, and includes the following steps:

[0060] Step a) Use the same gas mixture ratio and flow rate as in Example 1.

[0061] Step b) The use of the auxiliary catalyst is the same as in Example 1.

[0062] Step c) uses the same ultrasonic rinsing procedure as in Example 1, but after plasma treatment, an atomic layer deposition (ALD) technique is used to deposit a titanium dioxide (TiO2) film with a thickness of about 2 nm on the surface of the copper substrate to enhance the adhesion between the graphene and the substrate.

[0063] Step d) The preheating temperature and time are the same as in Example 1.

[0064] Step e) The reaction conditions are the same as in Example 1.

[0065] Step f) The rinsing procedure is the same as in Example 1.

[0066] Step g) The control system is the same as in Example 1, but the changes in the surface state of the substrate need to be monitored during the deposition process to ensure that the ALD layer does not affect the growth of graphene.

[0067] In addition to Raman spectroscopy and X-ray photoelectron spectroscopy, step h) also includes testing the adhesion strength between graphene and the substrate to verify the enhancement effect.

[0068] In summary:

[0069] Example 1 improves the quality and uniformity of graphene films by selecting methane as the carbon source and mixing it with hydrogen in a 1:15 ratio, ensuring the effective utilization of carbon elements in the mixed gas and improving the uniformity and quality of the graphene film.

[0070] Adding trace amounts of tungsten hexafluoride (WF6) as a co-catalyst optimized the graphene growth conditions and further improved the film quality. Ultrasonic cleaning and plasma treatment effectively removed contaminants and impurities from the copper foil surface, increasing the active sites on the substrate surface and promoting uniform graphene growth.

[0071] By depositing a 1 nm thick nickel transition metal layer on the substrate surface, the adhesion between graphene and the substrate was enhanced, which is particularly important for subsequent transfer steps.

[0072] By employing a PLC controller combined with a PID algorithm, real-time monitoring and regulation of gas flow rate, temperature, and pressure were achieved, ensuring the uniform growth of monolayer graphene. An online quality inspection system was used to monitor the quality of the graphene in real time, ensuring the high purity and consistency of the final product.

[0073] Alternating washing with ultrapure water and isopropanol, followed by purging and drying with nitrogen, thoroughly removed residues from the substrate, preventing oxidation and improving product purity. Raman spectroscopy and X-ray photoelectron spectroscopy analysis of the grown graphene confirmed its monolayer structure and absence of significant defects, and verified its chemical composition and purity.

[0074] Example 2 increased the graphene growth rate by accelerating the carbon source supply rate through increasing the total flow rate of the mixed gas to 120 sccm. To account for the increased flow rate, the actual amount of WF6 added was adjusted to maintain a consistent concentration, thus optimizing the growth conditions.

[0075] Extending the plasma treatment time from 10 minutes to 15 minutes further improved the cleanliness of the substrate surface, contributing to better graphene growth quality. Increasing the preheating temperature to 300℃ accelerated the decomposition of the oxide layer on the substrate surface, improving the graphene growth environment. Increasing the reaction temperature to 1050℃ promoted a faster chemical reaction rate, increasing growth efficiency.

[0076] Increased nitrogen purging time: Increasing the nitrogen purging time ensures the substrate is completely dry, avoiding the impact of residual moisture on graphene. A compensation mechanism for flow rate changes was added to the automated control system, adapting to temperature and pressure control at higher flow rates and ensuring consistent growth conditions.

[0077] Example 3 demonstrates how depositing a 2 nm thick titanium dioxide (TiO2) film on the substrate surface enhances the adhesion between graphene and the substrate, improving the integrity and stability during the transfer process. Monitoring changes in the substrate surface state during deposition ensures that the ALD layer does not affect graphene growth, thus guaranteeing the quality of the final product.

[0078] The adhesion strength between graphene and the substrate was tested, which verified the enhancement effect and provided a reliable guarantee for subsequent applications.

[0079] Example 4

[0080] This embodiment protects a continuous chemical vapor deposition method for preparing high-purity monolayer graphene, which is used to improve the uniformity and quality of graphene films:

[0081] This embodiment aims to optimize growth conditions and improve the quality and uniformity of graphene films by adding various catalysts and other auxiliary substances, including the following steps:

[0082] Step a) Methane is selected as the carbon source precursor gas and mixed with hydrogen at a volume ratio of 1:15 to form a mixed gas. In addition, boron trichloride (BCl3) at a weight percentage of 0.03% is added to the mixed gas as an auxiliary catalyst.

[0083] Step b) Add 0.05% by weight of tungsten hexafluoride (WF6) as the main catalyst and 0.01% by weight of copper chloride (CuCl2) as the auxiliary catalyst to the mixed gas.

[0084] Step c) High-purity copper foil with a thickness of approximately 25 μm is selected as the substrate material. Before use, the copper foil is cleaned in acetone, isopropanol, and ultrapure water for at least 5 minutes each using an ultrasonic cleaner. Subsequently, the cleaned copper foil is placed in a plasma cleaning device and treated with argon plasma at a power of 100W for 10 minutes. After plasma treatment, a 1 nm thick nickel (Ni) layer is deposited on the surface of the copper foil as an auxiliary adhesion layer.

[0085] Step d) The substrate material needs to be preheated before the mixed gas is introduced. The preheating temperature is 250°C and the time is 20 minutes.

[0086] Step e) The preheated copper foil is transferred to the chemical vapor deposition reaction chamber. The chamber walls must be made of a high-temperature-resistant material (such as quartz or a high-temperature alloy). A temperature gradient control device is installed within the reaction chamber to maintain a constant temperature of 1000°C. The pressure within the reaction chamber is maintained at approximately 150 Pa, and the total flow rate of the mixed gas is controlled at 100 sccm. During the reaction, the substrate material is rotated uniformly at 60 revolutions per minute by a rotary table.

[0087] After growth is completed in step f), the cells are cleaned alternately with ultrapure water and isopropanol. The cells are then cleaned in ultrapure water for 5 minutes using an ultrasonic cleaner, followed by cleaning in isopropanol for 5 minutes. After each cleaning, the cells are purged and dried with nitrogen.

[0088] Step g) Throughout the entire chemical vapor deposition reaction process, the gas flow rate, temperature, and pressure are monitored and regulated in real time by an automated control system.

[0089] Step h) The obtained graphene was characterized by Raman spectroscopy (using a 532 nm laser excitation with a resolution of 1 cm⁻¹) and X-ray photoelectron spectroscopy (using an AlKα X-ray source with an energy resolution of less than 0.5 eV) to ensure that it was a monolayer without obvious defects and to confirm its chemical composition and purity.

[0090] Example 5

[0091] This embodiment protects a continuous chemical vapor deposition method for preparing high-purity monolayer graphene, used to optimize the growth conditions of graphene films:

[0092] This embodiment aims to optimize the growth conditions of graphene films by adding multiple catalysts and adjusting other conditions, thereby improving the quality and uniformity of the films. The steps include:

[0093] Step a) Methane is selected as the carbon source precursor gas and mixed with hydrogen at a volume ratio of 1:15 to form a mixed gas. In addition, titanium tetrachloride (TiCl4) at a weight percentage of 0.02% is added to the mixed gas as an auxiliary catalyst.

[0094] Step b) Add 0.05% by weight of tungsten hexafluoride (WF6) as the main catalyst and 0.01% by weight of ferric chloride (FeCl3) as the auxiliary catalyst to the mixed gas.

[0095] Step c) High-purity copper foil with a thickness of approximately 25 μm was selected as the substrate material. Before use, the copper foil was cleaned in acetone, isopropanol, and ultrapure water for at least 5 minutes each using an ultrasonic cleaner. Subsequently, the cleaned copper foil was placed in a plasma cleaning device and treated with argon plasma at a power of 100W for 10 minutes. After plasma treatment, a 2 nm thick titanium dioxide (TiO2) film was deposited on the surface of the copper foil as an auxiliary adhesion layer.

[0096] Step d) The substrate material needs to be preheated before the mixed gas is introduced. The preheating temperature is 250°C and the time is 20 minutes.

[0097] Step e) The preheated copper foil is transferred to the chemical vapor deposition reaction chamber. The chamber walls must be made of a high-temperature-resistant material (such as quartz or a high-temperature alloy). A temperature gradient control device is installed within the reaction chamber to maintain a constant temperature of 1000°C. The pressure within the reaction chamber is maintained at approximately 150 Pa, and the total flow rate of the mixed gas is controlled at 100 sccm. During the reaction, the substrate material is rotated uniformly at 60 revolutions per minute by a rotary table.

[0098] After growth is completed in step f), the cells are cleaned alternately with ultrapure water and isopropanol. The cells are then cleaned in ultrapure water for 5 minutes using an ultrasonic cleaner, followed by cleaning in isopropanol for 5 minutes. After each cleaning, the cells are purged and dried with nitrogen.

[0099] Step g) Throughout the entire chemical vapor deposition reaction process, the gas flow rate, temperature, and pressure are monitored and regulated in real time by an automated control system.

[0100] Step h) The obtained graphene was characterized by Raman spectroscopy (using a 532 nm laser excitation with a resolution of 1 cm⁻¹) and X-ray photoelectron spectroscopy (using an AlKα X-ray source with an energy resolution of less than 0.5 eV) to ensure that it was a monolayer without obvious defects and to confirm its chemical composition and purity.

[0101] Comparative Example 1

[0102] This comparative example protects a continuous chemical vapor deposition method for preparing high-purity monolayer graphene, used to compare the effects of the comparative examples:

[0103] This comparative example aims to investigate the effects of simplified process steps and removal of all auxiliary catalysts on the quality and growth rate of graphene films.

[0104] Step a) Select methane as the carbon source precursor gas and mix it with hydrogen at a volume ratio of 1:15 to form a mixed gas.

[0105] Step b) proceeds directly to the next step without adding any auxiliary catalysts (tungsten hexafluoride, boron trichloride, copper chloride, titanium tetrachloride, ferric chloride, etc.).

[0106] Step c) High-purity copper foil is selected as the base material, with a thickness of approximately 25 μm. Before use, the copper foil is cleaned in an ultrasonic cleaner for at least 5 minutes each in acetone, isopropanol, and ultrapure water to remove surface oil and particulate matter. No plasma treatment or deposition of an auxiliary adhesion layer is performed.

[0107] Step d) The substrate material needs to be preheated before the mixed gas is introduced. The preheating temperature is 250°C and the time is 20 minutes.

[0108] Step e) Transfer the preheated copper foil into the chemical vapor deposition reaction chamber. The chamber walls must be made of a high-temperature-resistant material (such as quartz or a high-temperature alloy). The reaction chamber is equipped with a temperature gradient control device to maintain a constant temperature of 1000°C. The pressure inside the reaction chamber is maintained at approximately 150 Pa, and the total flow rate of the mixed gas is controlled at 100 sccm.

[0109] Step f) The substrate material is rotated at a constant speed of 60 revolutions per minute by a rotary table during the reaction process.

[0110] After step g) growth is complete, the cells are cleaned alternately with ultrapure water and isopropanol. The cells are then cleaned with an ultrasonic cleaner for 5 minutes in ultrapure water and then in isopropanol for 5 minutes. After each cleaning, the cells are purged with nitrogen and dried.

[0111] In step h), the gas flow rate, temperature, and pressure are monitored and adjusted in real time by an automated control system throughout the entire chemical vapor deposition process.

[0112] Step i) The obtained graphene was characterized by Raman spectroscopy (using a 532 nm laser excitation with a resolution of 1 cm⁻¹) and X-ray photoelectron spectroscopy (using an AlKα X-ray source with an energy resolution of less than 0.5 eV) to ensure that it was a monolayer without obvious defects and to confirm its chemical composition and purity.

[0113] By comparing these new embodiments with comparative examples, the effects of various catalysts and other auxiliary substances on the quality and growth rate of graphene films can be further evaluated.

[0114] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0115] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing high-purity monolayer graphene by continuous chemical vapor deposition, characterized in that: Includes the following steps: a) Use methane as a carbon source precursor gas and mix it with hydrogen at a volume ratio of 1:15 to form a mixed gas. b) Add 0.05% by weight of tungsten hexafluoride as an auxiliary catalyst to the mixed gas; c) Introduce the mixed gas over the pretreated copper substrate material; d) At a constant temperature of 1000℃ and a pressure of 150Pa, a chemical vapor deposition reaction was carried out to form a single layer of graphene. e) After growth is complete, the substrate is rinsed alternately with ultrapure water and isopropanol, and then purged with nitrogen to dry, removing any residues and obtaining a high-purity monolayer graphene product. Among them, by controlling gas flow rate, temperature and pressure, large-scale continuous production of single-layer graphene was achieved.

2. The method for preparing high-purity monolayer graphene by continuous chemical vapor deposition according to claim 1, characterized in that: The total flow rate of the mixed gas is 100 sccm and remains constant throughout the deposition process.

3. The method for preparing high-purity monolayer graphene by continuous chemical vapor deposition according to claim 1, characterized in that: The substrate material is pretreated by ultrasonic cleaning and plasma treatment before use. The plasma treatment is performed using argon gas for 10 minutes at a power of 100W.

4. The method for preparing high-purity monolayer graphene by continuous chemical vapor deposition according to claim 1, characterized in that: The chemical vapor deposition reaction is carried out in a reaction chamber equipped with a temperature gradient control device to achieve uniform distribution of graphene. The inner wall of the reaction chamber is made of high-temperature resistant material and is equipped with multiple temperature sensors to monitor temperature changes.

5. The method for preparing high-purity monolayer graphene by continuous chemical vapor deposition according to claim 1, characterized in that: It also includes preheating the substrate material before the chemical vapor deposition reaction, with a preheating temperature of 250°C and a time of 20 minutes.

6. The method for preparing high-purity monolayer graphene by continuous chemical vapor deposition according to claim 1, characterized in that: The rinsing process also includes rinsing in ultrapure water for 5 minutes using an ultrasonic cleaner, followed by rinsing in isopropanol for 5 minutes, and drying with nitrogen gas after each rinse.

7. The method for preparing high-purity monolayer graphene by continuous chemical vapor deposition according to claim 1, characterized in that: The method further includes using an automated control system to monitor and adjust the gas flow rate, temperature, and pressure during the chemical vapor deposition reaction process in real time, and monitoring the quality of graphene in real time through an online quality inspection system, wherein the automated control system includes a PLC controller and a PID algorithm.

8. The method for preparing high-purity monolayer graphene by continuous chemical vapor deposition according to claim 7, characterized in that: The substrate material undergoes surface modification treatment before use to enhance the adhesion between graphene and the substrate.

9. The method for preparing high-purity monolayer graphene by continuous chemical vapor deposition according to claim 1, characterized in that: During the chemical vapor deposition process, the substrate material is rotated at a speed of 60 revolutions per minute by a rotary table.

10. The method for preparing high-purity monolayer graphene by continuous chemical vapor deposition according to claim 1, characterized in that: The method also includes characterizing the obtained graphene by Raman spectroscopy after growth to ensure that it is a monolayer without obvious defects, and confirming its chemical composition and purity by X-ray photoelectron spectroscopy. The Raman spectroscopy analysis used a 532 nm laser excitation with a resolution of 1 cm⁻¹; the X-ray photoelectron spectroscopy analysis used an AlKα X-ray source with an energy resolution of less than 0.5 eV.

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