Preparation method of tubular graphene

Abstract

The invention discloses a preparation method of tubular graphene. The preparation method comprises the following steps: S1, carrying out surface polishing treatment and cleaning on an iron wire; s2, the iron wire is put into a quartz tube, argon mixed with hydrogen is introduced as shielding gas, the iron wire is heated and stayed, an oxide layer on the surface of the iron wire is removed, and a sample is obtained; s3, after the sample is cooled, closing the shielding gas, taking out the sample, mixing the sample into carbon powder with nanoscale particle size, taking out the sample, and putting the sample into the quartz tube again; argon mixed with hydrogen is introduced, the quartz tube is heated and stays, and then the quartz tube is rapidly moved out of the heating furnace to be cooled; s4, after the sample is cooled, closing the shielding gas, taking out the sample, cleaning and carrying out secondary polishing; and S5, putting the sample subjected to secondary polishing into the quartz tube again, heating and staying under the protection of introducing argon mixed with hydrogen, then cooling at a high speed and staying, then cooling at a high speed, and then cooling along with the furnace to finally obtain the tubular graphene. The process is low in development cost and high in yield.

Description

TECHNICAL FIELD

[0001] The present invention belongs to the field of graphene, and is mainly about a new process for preparing tubular graphene. BACKGROUND

[0002] Tubular graphene is a special morphology of graphene, usually refers to the tubular or nanotubular structure formed by rolling two-dimensional graphene sheets. Although it has structural similarity with carbon nanotubes (CNTs), its synthesis method, performance control and application field have unique characteristics. The main preparation methods at present are as follows: 1, chemical vapor deposition (CVD) combined with template method, researchers use porous alumina or polymer template to guide graphene growth to form tubular structure. By adjusting the template pore size and reaction conditions, tubular graphene with controllable diameter can be prepared (2021, Nature Materials). 2, self-rolling technology, two-dimensional graphene sheets are spontaneously rolled into tubes driven by stress engineering or interfacial tension, for example, after depositing graphene on a metal substrate, selective etching is used to release internal stress to form a tubular structure (2022, Advanced Materials). 3, 3D printing and directional assembly; combined with 3D printing technology, graphene nanosheets are directionally assembled into a tubular network structure for customized devices (2023, Science Advances).

[0003] The application fields of tubular graphene are as follows: 1, energy storage; supercapacitor: the high specific surface area (2600 m² / g) and open pore structure of tubular graphene improve ion transport efficiency, and the capacitance value reaches 350 F / g (2023, Energy & Environmental Science). 2, lithium / sodium ion battery: as a negative electrode material, the tubular structure relieves volume expansion, and the cycle life is improved to more than 2000 times; 3, electronic devices, used for high-frequency transistors and flexible circuits, with a carrier mobility of more than 10 5 cm² / V•s (2021, Nature Electronics); 4, transparent conductive film (transmittance > 95%, square resistance < 50 Ω / sq); 5, biomedical.

[0004] The current various preparation methods are limited to the laboratory, and a low-cost, high-yield preparation process needs to be developed. SUMMARY

[0005] In view of the above technical problems, the purpose of the present invention is to propose a simple and effective preparation process for tubular graphene, which has low development cost, simple process and high yield, and can more accurately control the tube diameter and layer number.

[0006] This invention proposes a method for preparing tubular graphene, the method comprising the following steps: S1 performs surface polishing and cleaning on the metal wire; S2. The iron wire is placed in a quartz tube, and argon gas mixed with hydrogen is introduced as a protective gas. The quartz tube is heated to a first set temperature and held at the first set temperature for a first set time to remove the oxide layer on the surface of the iron wire and obtain a sample. After the sample has cooled to room temperature, turn off the protective gas, remove the sample, mix it with carbon powder with nano-sized particles, remove it, and put it back into the quartz tube. Argon gas mixed with hydrogen is introduced to heat the quartz tube to a second set temperature, and the tube remains at the second set temperature for a second set time. Then the quartz tube is quickly removed from the heating furnace for cooling. After the sample has cooled to room temperature, turn off the protective gas, remove the sample, clean the carbon powder on the surface, and perform a second polishing of the surface. S5 After secondary polishing, the sample is placed back into the quartz tube. Under the protection of argon gas mixed with hydrogen, the quartz tube is heated to a third set temperature and held at the third set temperature for a third set time. Then, it is cooled down to a fourth set temperature at a first set rate and held at the fourth set temperature for a fourth set time. Then, it is cooled down at a second set rate to a fifth set temperature and then cooled with the furnace to finally obtain tubular graphene.

[0007] Furthermore, the argon gas containing hydrogen is argon gas mixed with 5-10% hydrogen.

[0008] Furthermore, the preparation method also includes step S6, which involves performing Raman spectroscopy on the tubular graphene obtained in step S5 to verify the growth of graphene on the surface of the tubular graphene.

[0009] Furthermore, the quartz tube is heated to a first set temperature, and the temperature is maintained at the first set temperature for a first set duration, specifically as follows: The quartz tube is heated to 450-700℃ and held at 450-700℃ for 30-60 minutes.

[0010] Furthermore, the quartz tube is heated to a second set temperature, and the second set temperature condition is maintained for a second set duration, specifically as follows: The quartz tube is heated to 1000-1200℃ and held at 1000-1200℃ for 5-15 minutes.

[0011] Further, the quartz tube is heated to a third set temperature, and stays at the third set temperature for a third set time period, specifically: The quartz tube is heated to 1000-1100 DEG C, and stays at 1000-1100 DEG C for 10-30 min.

[0012] Further, the temperature is lowered to a fourth set temperature at a first set speed, and stays at the fourth set temperature for a fourth set time period, specifically: The temperature is lowered to 900 DEG C at a speed of 1 DEG C / min, and stays at 900 DEG C for 10 min.

[0013] Further, the temperature is lowered at a second set speed, and the temperature is lowered to a fifth set temperature, specifically: The temperature is lowered at a speed of 2 DEG C / min, and the temperature is lowered to 700 DEG C.

[0014] Compared with the prior art, the above technical scheme has the following technical effects: 1. Simple process; 2. Low cost of required equipment conditions; 3. Controllable diameter, layer number and length of the tubular graphene. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic diagram of the Raman spectra of the product obtained in the example before and after secondary anti-diffusion. DETAILED DESCRIPTION

[0016] The electromagnetic pose detection system and method of the present application are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present application, not all.

[0017] Example 1:

[0018] The present application is a preparation method of tubular graphene, which comprises the following steps: S1, surface polishing treatment and cleaning of the metal wire; in this embodiment, iron wire with a diameter of 100-1000 microns and a length of 5-50 mm is selected as the metal wire material; The present application uses inexpensive iron wire as a catalyst for carbon decomposition and a template for forming a tubular structure. This eliminates the need for special preparation and subsequent removal of expensive templates.

[0019] S2, the iron wire is placed in a quartz tube, argon mixed with hydrogen is introduced as a protective gas, the quartz tube is heated to a first set temperature, and stays at the first set temperature for a first set time period, the oxide layer on the surface of the iron wire is removed, and a sample is obtained; S3After the sample is cooled to room temperature, the protective gas is turned off, the sample is taken out, and the sample is mixed into the carbon powder of nanoscale particle size before being taken out again and placed into the quartz tube; The nanoscale carbon powder is used as a solid carbon source to replace the gaseous carbon source (such as methane and ethylene) that is flammable, explosive and high in price and commonly used in the CVD method.

[0020] The argon mixed with hydrogen is introduced, the quartz tube is heated to the second set temperature, and is kept at the second set temperature for a second set time, and then the quartz tube is quickly removed from the heating furnace for cooling; S4After the sample is cooled to room temperature, the protective gas is turned off, the sample is taken out, and the surface carbon powder is cleaned and polished again. S5The sample after the second polishing is placed into the quartz tube again, the quartz tube is heated to the third set temperature under the protection of the argon mixed with hydrogen, and is kept at the third set temperature for a third set time, then is cooled to the fourth set temperature at the first set speed, and is kept at the fourth set temperature for a fourth set time, and then is cooled at the second set speed to the fifth set temperature, and is cooled with the furnace to obtain the tubular graphene.

[0021] The core equipment of the preparation process scheme provided in this embodiment is a tube furnace, which is a conventional heating equipment in the field of material preparation, and does not need a complex vacuum system or a precise gas flow control system (only needs to introduce a protective gas). The size of the tube diameter is adjusted and controlled through the diameter of the metal wire, the number of layers of graphene can be controlled by the temperature and time of the second diffusion, and the number of layers is less when the time is short and the temperature is low, and the number of layers is more when the time is long and the temperature is high.

[0022] Further, the argon mixed with hydrogen is argon mixed with 5-10% hydrogen.

[0023] Embodiment 2:

[0024] On the basis of embodiment 1, the preparation method provided in this embodiment further comprises S6, which is to test and verify the tubular graphene obtained in S5 by a Raman spectrum to test the growth of the graphene on the surface of the tubular graphene.

[0025] The scheme provided in this embodiment embeds a Raman spectrum verification step, which directly proves the successful preparation and high quality of the product through scientific data, and enhances the credibility and reproducibility of the method.

[0026] Embodiment 3:

[0027] On the basis of embodiments 1 and 2, in this embodiment, the quartz tube is heated to the first set temperature and kept at the first set temperature for a first set time, and the first set temperature and the first set time are specifically: heating the quartz tube to 450-700℃ and keeping the quartz tube at 450-700℃ for 30-60 minutes.

[0028] heating the quartz tube to a second set temperature and keeping the quartz tube at the second set temperature for a second set time period, wherein the second set temperature is 1000-1200℃ and the second set time period is 5-15 minutes. heating the quartz tube to 450-700℃ and keeping the quartz tube at 450-700℃ for 30-60 minutes.

[0029] heating the quartz tube to a third set temperature and keeping the quartz tube at the third set temperature for a third set time period, wherein the third set temperature is 1000-1100℃ and the third set time period is 10-30 minutes. heating the quartz tube to 450-700℃ and keeping the quartz tube at 450-700℃ for 30-60 minutes.

[0030] Example 4:

[0031] on the basis of example 1, 2 or 3, in this example, the temperature is lowered to a fourth set temperature at a first set speed, and the temperature is kept at the fourth set temperature for a fourth set time period, wherein the fourth set temperature is 900℃ and the fourth set time period is 10 minutes. the temperature is lowered to 900℃ at a speed of 1℃ / min, and the temperature is kept at 900℃ for 10 minutes.

[0032] the temperature is lowered at a second set speed, and the temperature is lowered to a fifth set temperature, wherein the second set speed is 2℃ / min and the fifth set temperature is 700℃. the temperature is lowered at a speed of 2℃ / min, and the temperature is lowered to 700℃.

[0033] As shown in the figure, FW-O is the sample after carbon diffusion and before the second high-temperature slow cooling, and the Raman spectrum test result shows that there is no carbon peak, which proves that the second polishing in step S4 effectively removes the physically adsorbed carbon powder on the surface, and ensures that the final graphene is derived from the carbon precipitation in the iron body, rather than surface contamination. FW-SD is the sample after the second high-temperature slow cooling, and the Raman test result shows that there is a higher peak around 2700nm, which is a typical graphene peak, indicating that graphene is precipitated on the surface of the iron wire after the second high-temperature slow cooling, which is the characteristic peak of high-quality graphene, and it is proved that high-quality graphene is successfully prepared on the surface of the iron wire by the method.

[0034] In this example, the heating of the quartz tube to a second set temperature and the keeping of the quartz tube at the second set temperature for a second set time period can be adjusted to adjust the thickness of the graphene. The shorter the time and the lower the temperature, the fewer the layers; the longer the time and the higher the temperature, the more the layers. Specifically, the quartz tube can be heated to 1000-1200℃ and kept at 1000-1200℃ for 5-15 minutes.

[0035] The above detailed description of the specific embodiments of the present application is provided for the purpose of further explaining the objects, technical solutions and advantages of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing tubular graphene, characterized in that, The preparation method includes the following steps: S1 performs surface polishing and cleaning on the metal wire; S2. The iron wire is placed in a quartz tube, and argon gas mixed with hydrogen is introduced as a protective gas. The quartz tube is heated to a first set temperature and held at the first set temperature for a first set time to remove the oxide layer on the surface of the iron wire and obtain a sample. After the sample has cooled to room temperature, turn off the protective gas, remove the sample, mix it with carbon powder with nano-sized particles, remove it, and put it back into the quartz tube. Argon gas mixed with hydrogen is introduced to heat the quartz tube to a second set temperature, and the tube remains at the second set temperature for a second set time. Then the quartz tube is quickly removed from the heating furnace for cooling. After the sample has cooled to room temperature, turn off the protective gas, remove the sample, clean the carbon powder on the surface, and perform a second polishing of the surface. S5 After secondary polishing, the sample is placed back into the quartz tube. Under the protection of argon gas mixed with hydrogen, the quartz tube is heated to a third set temperature and held at the third set temperature for a third set time. Then, it is cooled down to a fourth set temperature at a first set rate and held at the fourth set temperature for a fourth set time. Then, it is cooled down at a second set rate to a fifth set temperature and then cooled with the furnace to finally obtain tubular graphene.

2. The method for preparing tubular graphene according to claim 1, characterized in that, The argon gas used in the hydrogen gas is argon gas mixed with 5-10% hydrogen gas.

3. The method for preparing tubular graphene according to claim 1, characterized in that, The preparation method further includes step S6, which involves performing Raman spectroscopy on the tubular graphene obtained in step S5 to verify the growth of graphene on the surface of the tubular graphene.

4. The method for preparing tubular graphene according to claim 2, characterized in that, The process of heating the quartz tube to a first set temperature and maintaining that temperature for a first set duration is as follows: The quartz tube is heated to 450-700℃ and held at 450-700℃ for 30-60 minutes.

5. The method for preparing tubular graphene according to claim 2, characterized in that, The quartz tube is heated to a second set temperature, and the second set time is maintained at the second set temperature for the following specific duration: The quartz tube is heated to 1000-1200℃ and held at 1000-1200℃ for 5-15 minutes.

6. The method for preparing tubular graphene according to claim 2, characterized in that, The quartz tube is heated to a third set temperature, and the third set time is maintained at the third set temperature for the following specific duration: The quartz tube is heated to 1000-1100℃ and held at 1000-1100℃ for 10-30 minutes.

7. The method for preparing tubular graphene according to claim 2, characterized in that, The temperature is reduced to the fourth set temperature at the first set rate, and then maintained at the fourth set temperature for the fourth set duration, specifically as follows: The temperature was reduced to 900℃ at a rate of 1℃ / min and held at 900℃ for 10 minutes.

8. The method for preparing tubular graphene according to claim 2, characterized in that, The temperature is reduced at the second set rate until it reaches the fifth set temperature, specifically as follows: The temperature was reduced to 700℃ at a rate of 2℃ / min.

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