A method for preparing high-quality vertical graphene by coupling plasma technology with joule heating technology

Abstract

The application relates to the technical field of high-performance carbon material preparation, in particular to a method for preparing high-quality vertical graphene by coupling plasma technology and Joule heat technology. The application provides a method for preparing high-quality vertical graphene by coupling plasma and Joule heat technology. In the process of growing vertical graphene, the carrier and the vertical graphene film are intermittently subjected to instantaneous high-temperature treatment by utilizing the instantaneous high temperature of Joule heat to regulate the growth quality of graphene. The method for preparing high-quality vertical graphene by coupling plasma and Joule heat technology is used for processing, and after the coupling of Joule heat, the morphology of the vertical graphene is not affected, the ID / IG of the grown vertical graphene is obviously reduced from 1.26 to 0.98, which indicates that the graphitization degree of the vertical graphene is greatly improved, the defects in the growth process are reduced, and the infrared heat dissipation capacity of the graphene is improved.

Description

Technical Field

[0001] This application relates to the field of high-performance carbon material preparation technology, and in particular to a method for preparing high-quality vertical graphene by coupling plasma technology and Joule heating technology. Background Technology

[0002] Since its discovery in 2004, graphene has found widespread applications in various fields, such as corrosion protection, electrochemical electrode additives, conductive carriers, and heat dissipation. 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 a plasma electric field, graphene grows upright, exhibiting a three-dimensional vertical morphology, i.e., 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. Graphene's high radiative heat dissipation performance 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, reducing its physicochemical stability and in-plane thermal conductivity, among other technical indicators.

[0003] While the quality of vertical graphene can be improved by introducing etching gases such as H2 into PECVD to remove amorphous carbon, numerous defects still remain. High-temperature (above 1500℃) (CN202110978796.8), directional freezing (CN201911093622.2), or the use of catalysts (CN202111437501.2) techniques can also partially improve graphene quality. However, these high-temperature processing steps are complex, require sophisticated equipment, and are energy-intensive.

[0004] Therefore, finding a method that is simple to operate, easy to control, low in energy consumption, environmentally friendly, and produces vertical graphene with excellent properties is currently a key research direction. Summary of the Invention

[0005] To address the aforementioned technical problems in the existing technology, this application provides a method for preparing high-quality vertical graphene by coupling plasma technology with Joule heating technology, which is specifically achieved through the following technical solution.

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

[0007] (1) The substrate was fixed in the Joule heating and plasma co-processing reactor as a support for growing vertical graphene.

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

[0009] (3) Turn on the radio frequency plasma power supply and adjust the power to 500W. At the same time, turn on the Joule heating power supply and start the chemical vapor deposition of vertical graphene.

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

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

[0012] Furthermore, the substrate can be any one of semiconductor materials, metals, or carbon paper.

[0013] Furthermore, the Joule heating and plasma co-processing 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 via the first flange. One end of the third electrode passes through the second port and the first port of the three-way connector into the reaction chamber and is connected to one end of the reaction fixture via 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. One end of the first electrode is connected to the second electrode; the other end of the fourth electrode passes through the first port and the second port of the four-way connector into the reaction chamber, and is connected to the other end of the reaction fixture via a wire; the second port of the four-way connector is connected to the other end of the reaction chamber via 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 located outside the reaction chamber and between the third electrode and the reaction fixture; the second electrode is located outside the reaction chamber and 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, step (2) specifically involves heating the cavity temperature to 500°C.

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

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

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

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

[0021] (1) This invention provides a method for preparing high-quality vertical graphene using plasma-coupled Joule heating technology. By utilizing the instantaneous high temperature of Joule heating, the growth quality of graphene is controlled by intermittently subjecting the carrier and the vertical graphene film to instantaneous high-temperature treatment during the growth of vertical graphene.

[0022] (2) The method of preparing high-quality vertical graphene using plasma-coupled Joule heating technology of this application was used for processing. After coupling Joule heating, the morphology of vertical graphene was not affected. The ID / IG of the grown vertical graphene decreased significantly from 1.26 to 0.98, indicating that the graphitization degree of vertical graphene was greatly improved, the defects in the growth process were reduced, and thus the infrared heat dissipation capability of graphene was improved. Attached Figure Description

[0023] Figure 1 These are comparative images (scanning electron microscope images, i.e., SEM images) of the morphology of vertical graphene grown by conventional PECVD and vertical graphene grown by plasma-coupled Joule heating in Example 1, where (a) is vertical graphene prepared by PECVD, and (b) is vertical graphene prepared by Joule heating coupled with plasma. Figure 1 It can be observed that coupling Joule heating has no effect on the morphology of vertical graphene.

[0024] Figure 2 These are Raman spectra of vertical graphene grown by conventional PECVD and vertical graphene grown by plasma-coupled Joule heating in Example 1, where (a) is vertical graphene prepared by PECVD and (b) is vertical graphene prepared by Joule heating coupled with plasma. Figure 2 It can be observed that after coupling with Joule heating, the I of the grown vertical graphene... D / I G The value decreased significantly, from 1.26 to 0.98, indicating that the graphitization degree of vertical graphene was greatly improved. Detailed Implementation

[0025] The technical solution of this application will be further defined below with reference to specific implementation methods, but the scope of protection is not limited to the description.

[0026] Example 1

[0027] 1. The size is 2*3cm 2 The carbon cloth was ultrasonically cleaned with alcohol for 5 minutes and then dried for later use.

[0028] 2. Secure both ends of the cleaned carbon cloth with Joule heating clamps and place it in the center of the reaction chamber. Turn on the mechanical pump to purge the air from the chamber. Introduce CH4, Ar, and H2 gases into the chamber via the touchscreen at rates of 20, 10, and 10 sccm, respectively. Maintain the vacuum level in the chamber at 30 Pa by adjusting the valves.

[0029] 3. Turn on the heating device and set it to 10℃ for 1 minute. -1 Heat to 500°C at a constant rate and maintain until the reaction is complete.

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

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

[0032] 6. Remove the sample and preserve it.

[0033] The sample from Example 1 was tested, as follows:

[0034] Visual inspection revealed that the Joule heating coupling had no effect on the morphology of the vertical graphene, as shown in the test results. Figure 1 As shown.

[0035] By detecting the degree of graphitization, it can be found that the Ig of the vertically grown graphene after Joule heating is increased. D / I G The value decreased significantly, from 1.26 to 0.98, indicating a substantial improvement in the graphitization degree of vertical graphene. The test results are as follows... Figure 2 As shown.

[0036] Finally, it should be noted that the above embodiments are merely representative examples of this application. Obviously, the technical solutions of this application are not limited to the above embodiments, and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the content disclosed in this application should be considered within the scope of protection of this application.

Claims

1. A method for preparing high-quality vertical graphene by coupling plasma technology with Joule heating technology, characterized in that, Includes the following steps: (1) The substrate was fixed in the Joule heating and plasma co-processing reactor as a support for growing vertical graphene; (2) Open the gas flow meter to introduce CH4, Ar and H2, and adjust the mechanical pump valve to control the cavity pressure at 25-35Pa; turn on the heating power supply and heat the cavity temperature to 450-550℃ through the heating device, set the Joule heating program, voltage 55-65 V, pulse length 0.1-5 s, pulse interval 5-30 s; (3) Turn on the radio frequency plasma power supply and adjust the power to 500 W. At the same time, turn on the Joule heating power supply and start the chemical vapor deposition of vertical graphene. (4) After reacting for 5 to 15 minutes, turn off the radio frequency power supply, Joule heating power supply, heating power supply, gas flow meter and mechanical pump power supply in sequence; (5) Wait until the temperature drops to room temperature and then remove the sample.

2. The method for preparing high-quality vertical graphene by coupling plasma technology and Joule heating technology according to claim 1, characterized in that, The substrate can be any one of semiconductor materials, metals, or carbon paper.

3. The method for preparing high-quality vertical graphene by coupling plasma technology and Joule heating technology according to claim 1, characterized in that, The Joule heating and plasma co-processing 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 via the first flange. One end of the third electrode passes through the second port and the first port of the three-way connector into the reaction chamber and is connected to one end of the reaction fixture via 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 first electrode is connected to the second electrode; the other end of the fourth electrode passes through the first port 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 via a wire; the second port of the four-way connector is connected to the other end of the reaction chamber via the second flange; the third port of the four-way connector is connected to the external vacuum gauge; the fourth port of the four-way connector is connected to the external vacuum system; the first electrode is located outside the reaction chamber and between the third electrode and the reaction fixture; the second electrode is located outside the reaction chamber and 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 heating technology according to claim 1, characterized in that, The inlet 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 heating technology according to claim 1, characterized in that, In step (2), the pressure is controlled at 30 Pa.

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

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