Method for preparing high-quality vertical graphene by coupling plasma technology and Joule thermal technology

Abstract

The invention relates to the technical field of preparation of high-performance carbon materials, in particular to a method for preparing high-quality vertical graphene by coupling a plasma technology and a Joule thermal technology. The invention provides a method for preparing high-quality vertical graphene by using a plasma coupling Joule heat technology. The instantaneous high temperature of Joule heat is utilized, and in the vertical graphene growth process, instantaneous high-temperature treatment is discontinuously carried out on a carrier and a vertical graphene film to regulate and control the growth quality of graphene. When the method for preparing the high-quality vertical graphene by using the plasma coupling Joule heat technology is adopted for treatment, after the Joule heat is coupled, the morphology of the vertical graphene is not influenced, and the ID / IG of the grown vertical graphene is obviously reduced from 1.26 to 0.98, which shows that the graphitization degree of the vertical graphene is greatly improved, and the performance of the vertical graphene is greatly improved. The defects in the growth process are reduced, so that the infrared heat dissipation capability of the graphene is improved.

Description

Technical Field

[0001] The present application relates to the technical field of high-performance carbon material preparation, and in particular to a method for preparing high-quality vertical graphene by coupling plasma technology with Joule heat technology. Background Art

[0002] Since graphene was discovered in 2004, it has been widely used in various fields, such as corrosion protection, electrochemical electrode additives, conductive carriers, heat dissipation, etc. Its preparation methods include the initial mechanical exfoliation method, redox method, SiC epitaxial growth method, and chemical vapor deposition (CVD) of graphene films. In recent years, plasma enhanced chemical vapor deposition (PECVD) technology has been developed and applied to the growth and preparation of graphene. Under the action of the plasma electric field, graphene grows in an upright manner and presents a three-dimensional vertical morphology, that is, vertical graphene. Due to its advantages such as light weight, high conductivity, and large specific surface area, it is widely used as a current collector in electrochemical devices. The high radiation heat dissipation performance of graphene also makes vertical graphene films widely used in various heat dissipation scenarios. However, under plasma conditions, the rapid growth of graphene arrays leads to more surface defects, which reduces its physical and chemical stability and technical indicators such as in-plane heat conduction.

[0003] Although the quality of vertical graphene can be improved by introducing etching gases such as H2 in PECVD and removing amorphous carbon, there are still a lot of defects. The quality of graphene can also be partially improved by high temperature (above 1500°C) (CN202110978796.8) or directional freezing (CN201911093622.2) or using catalysts (CN202111437501.2). However, the later high-temperature processing steps are complicated, require high equipment and consume energy.

[0004] Therefore, finding a method that has simple process operation, easy process control, low energy consumption, environmental friendliness, and excellent properties for preparing vertical graphene is the current key research direction. Summary of the invention

[0005] In order to solve the above-mentioned technical problems existing in the prior art, the present application provides a method for preparing high-quality vertical graphene by coupling plasma technology and Joule heat technology, which is specifically achieved through the following technical solutions.

[0006] A method for preparing high-quality vertical graphene by coupling plasma technology with Joule heat technology comprises the following steps:

[0007] (1) Fixing the substrate as a carrier for growing vertical graphene into a Joule heat and plasma coordinated reactor;

[0008] (2) Turn on the gas flow meter to introduce CH4, Ar, and H2, and adjust the mechanical pump valve to control the cavity pressure at 25-35 Pa; turn on the heating power supply, and heat the cavity temperature to 450-550°C through the heating device, set the Joule heat program, voltage 55-65V, pulse length 0.1-5s, and pulse interval 5-30s;

[0009] (3) Turn on the RF plasma power supply, adjust the power to 500 W, and turn on the Joule heat power supply to start chemical vapor deposition of vertical graphene;

[0010] (4) After reacting for 5 to 15 minutes, turn off the RF power supply, Joule heat power supply, heating power supply, gas flow meter, and mechanical pump power supply in turn;

[0011] (5) Wait until the temperature drops to room temperature and take out the sample.

[0012] Furthermore, the substrate is any one of semiconductor material, metal, and carbon paper.

[0013] Furthermore, the Joule heat and plasma collaborative reactor specifically includes a pulse power supply, a radio frequency generator, a first flange, a second flange, a first electrode, a second electrode, a third electrode, a fourth electrode, a four-way connector, a three-way connector, a reaction fixture and a reaction chamber; one end of the reaction chamber is connected to the first port of the three-way connector through the first flange; one end of the third electrode passes through the second port of the three-way connector and the first port of the three-way connector to enter the reaction chamber, and is connected to one end of the reaction fixture through a wire; the third port of the three-way connector is connected to an external air intake system; the other end of the third electrode is connected to one end of the pulse power supply; the other end of the pulse power supply is connected to the fourth electrode The other end of the fourth electrode passes through the first port of the four-way connector and the second port of the four-way connector to enter the reaction chamber, and is connected to the other end of the reaction fixture through a wire; the second port of the four-way connector is connected to the other end of the reaction chamber through a second flange; the third port of the four-way connector is connected to an external vacuum gauge; the fourth port of the four-way connector is connected to an external vacuum system; the first electrode is arranged outside the reaction chamber and is located between the third electrode and the reaction fixture; the second electrode is arranged outside the reaction chamber and is located between the fourth electrode and the reaction fixture; one end of the radio frequency generator is connected to the first electrode; the other end of the radio frequency generator is connected to the second electrode. For detailed structure, please refer to patent CN113471051B.

[0014] Furthermore, the introduction rates of CH4, Ar and H2 are 20, 10 and 10 sccm respectively.

[0015] Furthermore, in step (2), the pressure is controlled at 30 Pa.

[0016] Furthermore, the step (2) is specifically to heat the cavity temperature to 500°C.

[0017] Furthermore, in step (2), the heating rate of the cavity during heating is 5-20°C min -1 .

[0018] Furthermore, in step (2), the specific voltage range is 55-65V.

[0019] Furthermore, in step (3), the power of the RF plasma power supply is 500W.

[0020] Compared with the prior art, the technical effects created by this application are embodied in:

[0021] (1) The present invention provides a method for preparing high-quality vertical graphene using plasma-coupled Joule heating technology. The instantaneous high temperature of Joule heat is utilized to intermittently perform instantaneous high temperature treatment on the carrier and the vertical graphene film during the growth process of the vertical graphene to regulate the growth quality of the graphene.

[0022] (2) The method of preparing high-quality vertical graphene using plasma-coupled Joule heating technology of the present application was used for processing. After coupling the Joule heat, the morphology of the vertical graphene was not affected, and the ID / IG of the grown vertical graphene was significantly reduced from 1.26 to 0.98, indicating that the degree of graphitization of the vertical graphene was greatly improved, and the defects in the growth process were reduced, thereby improving the infrared heat dissipation capacity of the graphene. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The following is a comparison of the morphologies of vertical graphene grown by ordinary PECVD method and vertical graphene grown by plasma coupled Joule heating technology in Example 1 (scanning electron microscope image, i.e. SEM image), where (a) vertical graphene prepared by PECVD, (b) vertical graphene prepared by Joule heating coupled plasma. Figure 1 It can be found that after coupling Joule heat, there is no effect on the morphology of vertical graphene.

[0024] Figure 2 The Raman spectra of the vertical graphene grown by the common PECVD method and the vertical graphene grown by the plasma coupled Joule heating technology in Example 1, wherein (a) the vertical graphene prepared by PECVD, and (b) the vertical graphene prepared by Joule heating coupled plasma. Figure 2 It can be found that after coupling Joule heat, the I D / I G It dropped significantly from 1.26 to 0.98, indicating that the degree of graphitization of vertical graphene has been greatly improved. DETAILED DESCRIPTION

[0025] The technical solution of the present application is further limited below in conjunction with specific implementation methods, but the scope of protection required is not limited to the description.

[0026] Example 1

[0027] 1. Change the size to 2*3cm 2 The carbon cloth was cleaned with alcohol ultrasonic for 5 min and dried for later use.

[0028] 2. Fix the two ends of the cleaned carbon cloth with Joule heat clamps and place them in the middle of the reaction chamber. Turn on the mechanical pump to evacuate the air in the chamber. Introduce CH4, Ar, and H2 gases into the chamber through the touch screen at a rate of 20, 10, and 10 sccm, respectively. Maintain the vacuum degree of the chamber at 30 Pa by adjusting the valve;

[0029] 3. Turn on the heating device at 10℃min. -1 The temperature was heated to 500°C and maintained at this temperature until the reaction was complete.

[0030] 4. Set the plasma power supply to 500 W and the reaction time to 8 min; set the Joule thermal voltage to 60 A and heat the carbon cloth substrate for 1 s every 29 s; turn on the plasma power supply and Joule thermal power supply switches to start graphene deposition.

[0031] 5. After the reaction is completed, turn off the plasma power supply and Joule heat power supply; turn off the heating device; turn off H2 and CH4, keep the vacuum chamber to maintain Ar inert atmosphere; cool to room temperature with the furnace.

[0032] 6. Take out the sample and save it.

[0033] The samples of Example 1 were tested as follows:

[0034] Through appearance inspection, it can be found that after coupling Joule heat, there is no effect on the morphology of vertical graphene. The test results are as follows Figure 1 shown.

[0035] By testing the degree of graphitization, it can be found that after coupling Joule heat, the I D / I G It dropped significantly from 1.26 to 0.98, indicating that the degree of graphitization of vertical graphene has been greatly improved. Figure 2 shown.

[0036] Finally, it should be pointed out that the above embodiments are only representative examples of the present application. Obviously, the technical solution of the present application is not limited to the above embodiments, and there may be many variations. All variations that can be directly derived or associated with the contents disclosed in the present application by a person of ordinary skill in the art should be considered as the protection scope of the present application.

Claims

1. A method for preparing high-quality vertical graphene by coupling plasma technology with Joule heating technology, characterized in that: The following steps are involved: (1) Fixing the substrate as a carrier for growing vertical graphene into a Joule heat and plasma coordinated reactor; (2) Turn on the gas flow meter to introduce CH4, Ar, and H2, and adjust the mechanical pump valve to control the cavity pressure at 25-35 Pa; turn on the heating power supply, and heat the cavity temperature to 450-550°C through the heating device, set the Joule heat program, voltage 55-65V, pulse length 0.1-5s, and pulse interval 5-30s; (3) Turn on the RF plasma power supply, adjust the power to 500 W, and turn on the Joule heat power supply to start chemical vapor deposition of vertical graphene; (4) After reacting for 5 to 15 minutes, turn off the RF power supply, Joule heat power supply, heating power supply, gas flow meter, and mechanical pump power supply in turn; (5) Wait until the temperature drops to room temperature and take out the sample.

2. The method for preparing high-quality vertical graphene by coupling plasma technology and Joule heat technology according to claim 1, characterized in that: The substrate is any one of semiconductor material, metal and carbon paper.

3. The method for preparing high-quality vertical graphene by coupling plasma technology and Joule heat technology according to claim 1, characterized in that: The Joule heat and plasma collaborative reactor specifically includes a pulse power supply, a radio frequency generator, a first flange, a second flange, a first electrode, a second electrode, a third electrode, a fourth electrode, a four-way connector, a three-way connector, a reaction fixture and a reaction chamber; one end of the reaction chamber is connected to the first port of the three-way connector through the first flange; one end of the third electrode passes through the second port of the three-way connector and the first port of the three-way connector to enter the reaction chamber, and is connected to one end of the reaction fixture through a wire; the third port of the three-way connector is connected to an external air intake system; the other end of the third electrode is connected to one end of the pulse power supply; the other end of the pulse power supply is connected to one end of the fourth electrode The fourth electrode is connected to the first end of the reaction chamber; the other end of the fourth electrode passes through the first port of the four-way connector and the second port of the four-way connector to enter the reaction chamber, and is connected to the other end of the reaction fixture through a wire; the second port of the four-way connector is connected to the other end of the reaction chamber through a second flange; the third port of the four-way connector is connected to an external vacuum gauge; the fourth port of the four-way connector is connected to an external vacuum system; the first electrode is arranged outside the reaction chamber and is located between the third electrode and the reaction fixture; the second electrode is arranged outside the reaction chamber and is located between the fourth electrode and the reaction fixture; one end of the radio frequency generator is connected to the first electrode; the other end of the radio frequency generator is connected to the second electrode.

4. The method for preparing high-quality vertical graphene by coupling plasma technology and Joule heat technology according to claim 1, characterized in that: The introduction rates of CH4, Ar and H2 are 20, 10 and 10 sccm respectively.

5. The method for preparing high-quality vertical graphene by coupling plasma technology and Joule heat technology according to claim 1, characterized in that: In the step (2), the pressure is controlled at 30 Pa.

6. The method for preparing high-quality vertical graphene by coupling plasma technology and Joule heat technology according to claim 1, characterized in that: The step (2) specifically involves heating the cavity to a temperature of 500°C.

7. The method for preparing high-quality vertical graphene by coupling plasma technology and Joule heat technology according to claim 1, characterized in that: In the step (2), the specific voltage range is 55-65V.

8. The method for preparing high-quality vertical graphene by coupling plasma technology and Joule heat technology according to claim 1, characterized in that: In the step (3), the power of the radio frequency plasma power supply is 500W.

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