Preparation method of graphene oxide

Abstract

The invention discloses a graphene oxide preparation method which is characterized by comprising the following steps: s1, putting concentrated sulfuric acid into a low-temperature constant-temperature container, and maintaining the temperature of the concentrated sulfuric acid at a first temperature; s2, opening a magnetic field penetrating through the low-temperature constant-temperature container through an electromagnetic device arranged in the low-temperature constant-temperature container; s3, adding a graphite raw material into concentrated sulfuric acid, and then adding potassium permanganate; s4, the temperature of the concentrated sulfuric acid is controlled to be the first temperature, and the temperature is maintained for 0.5-4 h; s5, raising the temperature of the concentrated sulfuric acid to a second temperature, and keeping the temperature at the second temperature for 0.5-1 hour; s6, sequentially repeating the steps s4 and s5 for a plurality of times to obtain a first reaction solution; s7, heating the first reaction solution to a third temperature, and keeping the temperature at the third temperature for 1-6 hours to obtain a second reaction solution; s8, deionized water is added into the second reaction solution, then a hydrogen peroxide solution with the mass fraction of 30% is added, continuous stirring is conducted, and a bright yellow solution is obtained; the graphene oxide has a layered structure, and the yield is high.

Description

Technical Field

[0001] The present invention relates to the technical field of graphene oxide, and in particular to a method for preparing graphene oxide. Background Art

[0002] Graphene oxide is an important derivative of graphene, produced by introducing reactive oxygen-containing groups onto graphene. Currently, the most common methods for preparing graphene oxide include the Brodie method, the Staudenmaier method, and the Hummers method. The Hummers method is currently the most commonly used laboratory preparation method.

[0003] However, chemical methods such as the Hummers method require heating and stirring oxidants such as concentrated sulfuric acid and potassium permanganate at a relatively high temperature (98°C), which is very dangerous. In addition, the resulting graphene oxide is usually a three-dimensional structure and requires further physical methods such as ultrasound to achieve thorough exfoliation and preparation. The operation process is complicated and the layered structure is easily destroyed during mechanical operation, resulting in low yield.

[0004] Therefore, how to develop a method for preparing graphene oxide with high safety, high universality and high yield, so as to achieve a layered structure of graphene oxide, and to ensure safety, high efficiency and high yield during the preparation process, has become a difficult problem that needs to be solved urgently in this field. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing graphene oxide, which can achieve a layered structure of graphene oxide, and the preparation process is safe, efficient and has a high output rate.

[0006] The present invention provides a method for preparing graphene oxide, comprising the following steps:

[0007] S1: placing concentrated sulfuric acid into a low-temperature constant temperature container and maintaining the temperature of the concentrated sulfuric acid at a first temperature;

[0008] s2: turning on the magnetic field passing through the cryostat container by an electromagnetic device provided in the cryostat container;

[0009] S3: Then add graphite raw material to concentrated sulfuric acid, and then add potassium permanganate;

[0010] S4: Control the temperature of concentrated sulfuric acid to the first temperature and maintain it for 0.5-4h;

[0011] S5: Raise the temperature of concentrated sulfuric acid to the second temperature and keep it at the second temperature for 0.5-1h;

[0012] s6: then repeat steps s4 and s5 several times in sequence to obtain a first reaction solution;

[0013] s7: heating the first reaction solution to a third temperature and maintaining the temperature at the third temperature for 1-6 hours to obtain a second reaction solution;

[0014] S8: Deionized water was added to the second reaction solution, followed by a 30% by mass hydrogen peroxide solution with continuous stirring to obtain a bright yellow solution;

[0015] s9: The bright yellow solution is precipitated, washed, and dried to obtain a black graphene oxide dispersion;

[0016] Preferably, the prepared graphene oxide has ultra-thin sheets, a relatively complete graphene layer structure, and is a two-dimensional layered material with rich functional groups such as hydroxyl, carboxyl, and carbonyl groups; the layer thickness of the graphene oxide is less than 10 nm; and the lateral size is ≥50 μm.

[0017] Compared with the prior art, the present invention has the following beneficial effects: through s2: an electromagnetic device provided in the low-temperature constant temperature container is used to open a magnetic field passing through the low-temperature constant temperature container; s3: a graphite raw material is then added to concentrated sulfuric acid, and then potassium permanganate is added; this is conducive to achieving intercalation of concentrated sulfuric acid, that is, the concentrated sulfuric acid is slowly ionized at a low temperature, releasing hydrogen ions that pass through the graphite layers of the graphite raw material, thereby facilitating the production of layered graphite and preventing damage to the graphite layers; under the action of potassium permanganate, the layered graphite is oxidized into partially layered graphite and into graphene oxide;

[0018] The autoionization of sulfuric acid is reversible. By controlling the temperature of concentrated sulfuric acid at the first temperature and maintaining it for 0.5-4 hours, it is beneficial to achieve a low reaction rate of the positive direction of the autoionization of sulfuric acid, thereby facilitating the ionized hydrogen ions to enter between the graphite raw materials. At the same time, it is beneficial to avoid the problem of excessively high local hydrogen ion concentration in the graphite raw materials during the intercalation process of concentrated sulfuric acid due to high hydrogen ion concentration, thereby avoiding the destruction of the degraphite layer.

[0019] By opening a magnetic field passing through the low-temperature constant-temperature container, the hydrogen ions entering the interlayers of the graphite raw material are directed to move under the action of the magnetic field, thereby increasing the gaps between the graphite layers of the graphite raw material, thereby avoiding the problem of being unable to achieve directed movement of hydrogen ions in the graphite layers of the graphite raw material due to too low temperature and too low hydrogen ion concentration;

[0020] By increasing the temperature of concentrated sulfuric acid to a second temperature and maintaining the temperature at the second temperature for 0.5-1 hour, the positive direction reaction rate of the autoionization of sulfuric acid is increased, and the hydrogen ion concentration is further increased, which is conducive to increasing the concentration of hydrogen ions entering between the layers of the graphite raw material. On the basis of the increase in the gap between the graphite layers of the graphite raw material in the early stage, the hydrogen ions move in a direction under the action of the magnetic field, thereby achieving the exfoliation of the graphite layers of the graphite raw material and improving the graphite layer exfoliation efficiency, while at the same time, the graphite layer damage rate is low;

[0021] Then, by sequentially repeating steps s4 and s5 several times, a first reaction solution is obtained, which achieves high stripping efficiency of the graphite layer of the graphite raw material and helps avoid damage to the graphite layer;

[0022] By heating the first reaction solution to a third temperature and keeping the temperature at the third temperature for 1-6 hours, the oxidation rate of the graphite layer after exfoliation is improved;

[0023] Deionized water is added to the second reaction solution, and then a 30% by mass hydrogen peroxide solution is added and continuously stirred to achieve complete oxidation of the graphite layer while avoiding excessive oxidation of part of the graphite layer, thereby obtaining graphene oxide.

[0024] Furthermore, the mass ratio of concentrated sulfuric acid, graphite raw material and potassium permanganate in s3 is (18.4-110.4): (1-10): (1.5-9).

[0025] The beneficial effect of adopting the previous step is that, by adding the amount of potassium permanganate, it is beneficial to achieve oxidation of the graphite layer at a lower temperature, and at the same time it is beneficial to avoid the problem of damage to the graphite layer structure caused by a high degree of oxidation of the graphite layer.

[0026] Furthermore, the first temperature is -5 to -1°C.

[0027] The beneficial effect of the above step is that the first temperature of -5 to -1°C is conducive to achieving a low reaction rate of the autoionization of sulfuric acid in the positive direction, thereby facilitating the ionized hydrogen ions to enter between the graphite raw materials, and facilitating avoiding the problem of excessively high local hydrogen ion concentration in the graphite raw materials during the intercalation process of concentrated sulfuric acid due to high hydrogen ion concentration, thereby facilitating avoiding the destruction of the degraphitized layer.

[0028] By opening a magnetic field passing through a low-temperature constant-temperature container, hydrogen ions entering between layers of the graphite raw material are directed to move under the action of the magnetic field, thereby increasing the gap between the graphite layers of the graphite raw material.

[0029] Furthermore, the second temperature is 10-35°C.

[0030] The beneficial effect of adopting the previous step is that the positive reaction rate of the autoionization of sulfuric acid is increased, and the hydrogen ion concentration is further increased, which is conducive to increasing the concentration of hydrogen ions entering the interlayer of the graphite raw material. On the basis of the increase in the gap between the graphite layers of the graphite raw material in the early stage, the hydrogen ions move in a direction under the action of the magnetic field, thereby realizing the exfoliation of the graphite layer of the graphite raw material and improving the graphite layer exfoliation efficiency, while the graphite layer damage rate is low.

[0031] Furthermore, in step s6, steps s4 and s5 are repeated 3-4 times in sequence to obtain a first reaction solution.

[0032] Furthermore, the magnetic field strength in steps s3-s5 is 0.01-0.025 Tesla; and in step s6, when steps s4 and s5 are repeated, the magnetic field strength is reduced.

[0033] Furthermore, the third temperature is 78-80°C.

[0034] Furthermore, the graphite raw material includes one of flake graphite, expanded graphite, and vermicular graphite.

[0035] Furthermore, the low-temperature constant temperature container includes a accommodating cavity with an upper end opening, and a first accommodating space sleeved outside the side wall of the accommodating cavity, wherein a first temperature control medium is provided in the first accommodating space, and the first temperature control medium is ethanol; the first accommodating space is provided with a first liquid inlet and a first liquid outlet, and the first liquid inlet is connected to the first temperature control medium constant temperature storage tank through a first circulation pump;

[0036] A second accommodating space is provided at the bottom of the accommodating cavity, and a second temperature-control medium is provided in the second accommodating space, and the second temperature-control medium is water; the second accommodating space is provided with a second liquid inlet and a second liquid outlet, and the second liquid inlet is connected to the second temperature-control medium constant temperature storage tank through a second circulation pump;

[0037] An electromagnetic device is provided on the inner side wall of the accommodating cavity or the outer side wall of the first accommodating space;

[0038] When the temperature of the concentrated sulfuric acid is controlled at the first temperature in step s4, the second temperature control medium in the second accommodating space is emptied, and the first circulation pump is turned on to circulate the first temperature control medium in the first accommodating space; the temperature of the first temperature control medium is -5 to -1°C;

[0039] When the temperature of the concentrated sulfuric acid is controlled to the second temperature in step s5, the first temperature control medium in the first accommodating space is emptied, and the second circulation pump is turned on to circulate the second temperature control medium in the second accommodating space; the temperature of the second temperature control medium is 10 to 35°C.

[0040] The beneficial effect of the above step is that the low-temperature constant-temperature container includes a receiving cavity with an upper opening, so that raw materials such as graphite raw material, concentrated sulfuric acid, potassium permanganate, etc. can be added into the receiving cavity for reaction;

[0041] By means of a first accommodation space sleeved outside the side wall of the accommodation chamber, a first temperature control medium is provided in the first accommodation space, and the first temperature control medium is ethanol, so that the temperature of the concentrated sulfuric acid is controlled at a first temperature, and the first temperature is -5 to -1°C and maintained for 0.5 to 4 hours, thereby facilitating a low positive reaction rate of the autoionization of sulfuric acid, facilitating the ionized hydrogen ions to enter between the graphite raw materials, and facilitating avoiding the problem of excessively high local hydrogen ion concentration in the graphite raw materials during the intercalation process of the concentrated sulfuric acid due to a high hydrogen ion concentration, thereby facilitating avoiding the destruction of the degraphitized layer;

[0042] A second accommodating space is provided at the bottom of the accommodating chamber, and a second temperature-controlling medium is provided in the second accommodating space. The second temperature-controlling medium is water, so that the temperature of the concentrated sulfuric acid is raised to a second temperature, and the second temperature is 10-35° C., and the second temperature is kept at the second temperature for 0.5-1 hour, thereby improving the positive reaction rate of the autoionization of sulfuric acid, further improving the hydrogen ion concentration, and facilitating the increase of the hydrogen ion concentration entering the interlayer of the graphite raw material. On the basis of the increase in the gap between the graphite layers of the graphite raw material in the early stage, the hydrogen ions move in a direction under the action of the magnetic field, which is conducive to the exfoliation of the graphite layer of the graphite raw material and improves the efficiency of the graphite layer exfoliation, while the graphite layer damage rate is low;

[0043] And it is possible to repeat steps s4 and s5 several times in sequence to obtain a first reaction solution, thereby improving the stripping efficiency of the graphite layer of the graphite raw material and helping to avoid damage to the graphite layer;

[0044] The first reaction solution can be heated from the first solution to the third temperature and kept at the third temperature for 1-6 hours. DETAILED DESCRIPTION

[0045] In order to better understand the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments.

[0046] Example 1:

[0047] According to this embodiment, a method for preparing graphene oxide is provided, comprising the following steps: s1: placing concentrated sulfuric acid in a low-temperature constant-temperature container and maintaining the concentrated sulfuric acid at a first temperature; specifically, transferring a certain amount of concentrated sulfuric acid into a dried 1000 mL beaker, placing a polytetrafluoroethylene rotor, and placing the beaker into the low-temperature constant-temperature container;

[0048] s2: turning on the magnetic field passing through the cryostat container by an electromagnetic device provided in the cryostat container;

[0049] s3: Then add graphite raw material to concentrated sulfuric acid, and then add potassium permanganate; the mass ratio of concentrated sulfuric acid, graphite raw material, and potassium permanganate is 64.4:5.5:5;

[0050] The graphite raw material includes flake graphite.

[0051] s4: controlling the temperature of concentrated sulfuric acid to a first temperature and maintaining it for 2 hours; the first temperature is -3°C;

[0052] s5: raising the temperature of concentrated sulfuric acid to a second temperature, and maintaining the temperature at the second temperature for 0.8 h; the second temperature is 23° C.;

[0053] s6: then repeat steps s4 and s5 three times in sequence to obtain a first reaction solution;

[0054] s7: heating the first reaction solution to a third temperature, and maintaining the temperature at the third temperature for 3.5 hours to obtain a second reaction solution; the third temperature is 79° C.;

[0055] S8: Deionized water was added to the second reaction solution, followed by a 30% by mass hydrogen peroxide solution with continuous stirring to obtain a bright yellow solution;

[0056] s9: The bright yellow solution is precipitated, washed, and dried to obtain a black graphene oxide dispersion.

[0057] The magnetic field strength in steps s3-s5 is 0.018 Tesla; when steps s4 and s5 are repeated in step s6, the magnetic field strength is reduced to 0.01 Tesla.

[0058] The prepared graphene oxide has ultra-thin sheets, a relatively complete graphene layer structure, and is a two-dimensional layered material with abundant functional groups such as hydroxyl, carboxyl, and carbonyl. The graphene oxide layer has a thickness of 8 nm and a lateral size of 65 μm.

[0059] The low-temperature constant temperature container includes a accommodating chamber with an upper opening, and a first accommodating space sleeved outside the side wall of the accommodating chamber. A first temperature control medium is provided in the first accommodating space, and the first temperature control medium is ethanol. The first accommodating space is provided with a first liquid inlet and a first liquid outlet. The first liquid inlet is connected to the first temperature control medium constant temperature storage tank through a first circulation pump.

[0060] A second accommodating space is provided at the bottom of the accommodating cavity, and a second temperature-control medium is provided in the second accommodating space, and the second temperature-control medium is water; the second accommodating space is provided with a second liquid inlet and a second liquid outlet, and the second liquid inlet is connected to the second temperature-control medium constant temperature storage tank through a second circulation pump;

[0061] An electromagnetic device is provided on the inner side wall of the accommodating cavity or the outer side wall of the first accommodating space;

[0062] When the temperature of the concentrated sulfuric acid is controlled at the first temperature in step s4, the second temperature control medium in the second accommodation space is emptied, and the first circulation pump is turned on to circulate the first temperature control medium in the first accommodation space; the temperature of the first temperature control medium is -3°C;

[0063] When the temperature of the concentrated sulfuric acid is controlled to the second temperature in step s5, the first temperature control medium in the first accommodating space is emptied, and the second circulation pump is turned on to circulate the second temperature control medium in the second accommodating space; the temperature of the second temperature control medium is 27°C.

[0064] Example 2:

[0065] The same contents as those in Example 1 will not be repeated here. The differences between this embodiment and Example 1 are as follows: This embodiment provides a method for preparing graphene oxide, further comprising:

[0066] s3: concentrated sulfuric acid, graphite raw material, potassium permanganate in a mass ratio of 90:9.5:8.5; the graphite raw material includes expanded graphite;

[0067] s4: controlling the temperature of concentrated sulfuric acid to the first temperature and maintaining it for 1 hour; the first temperature is -4.5°C;

[0068] s5: raising the temperature of concentrated sulfuric acid to a second temperature, and maintaining the temperature at the second temperature for 0.6 seconds; the second temperature is 13°C;

[0069] s6: then repeat steps s4 and s5 four times in sequence to obtain a first reaction solution;

[0070] s7: heating the first reaction solution to a third temperature, and maintaining the temperature at the third temperature for 5 hours to obtain a second reaction solution; the third temperature is 78.5° C.;

[0071] The magnetic field strength in steps s3-s5 is 0.015 Tesla; when steps s4 and s5 are repeated in step s6, the magnetic field strength is reduced by 0.01 Tesla.

[0072] When the temperature of the concentrated sulfuric acid is controlled at the first temperature in step s4, the temperature of the first temperature-control medium is -4.5°C;

[0073] When the temperature of the concentrated sulfuric acid is controlled to the second temperature in step s5, the temperature of the second temperature-control medium is 13°C.

[0074] The prepared graphene oxide has ultra-thin sheets, a relatively complete graphene layer structure, and is a two-dimensional layered material with abundant functional groups such as hydroxyl, carboxyl, and carbonyl. The graphene oxide has a layer thickness of 6 nm and a lateral size of 55 μm.

[0075] Example 3:

[0076] The same contents as those in Example 1 will not be repeated here. The differences between this embodiment and Example 1 are as follows: This embodiment provides a method for preparing graphene oxide, further comprising:

[0077] s3: The mass ratio of concentrated sulfuric acid, graphite raw material, and potassium permanganate is 20:2.5:1.8;

[0078] The graphite raw material includes flake vermicular graphite.

[0079] s4: Control the concentrated sulfuric acid temperature to the first temperature and maintain it for 3.5 hours; the first temperature is -1.5°C;

[0080] s5: raising the temperature of concentrated sulfuric acid to a second temperature, and maintaining the temperature at the second temperature for 0.8 h; the second temperature is 32° C.;

[0081] s7: heating the first reaction solution to a third temperature, and maintaining the temperature at the third temperature for 1.5 hours to obtain a second reaction solution; the third temperature is 79.5° C.;

[0082] The magnetic field strength in steps s3-s5 is 0.022 Tesla; when steps s4 and s5 are repeated in step s6, the magnetic field strength is reduced to 0.015 Tesla.

[0083] When the temperature of the concentrated sulfuric acid is controlled at the first temperature in step s4, the temperature of the first temperature-control medium is -1.5°C;

[0084] When the temperature of the concentrated sulfuric acid is controlled to the second temperature in step s5, the temperature of the second temperature-control medium is 32°C.

[0085] The prepared graphene oxide has ultra-thin sheets, a relatively complete graphene layer structure, and is a two-dimensional layered material with abundant functional groups such as hydroxyl, carboxyl, and carbonyl. The graphene oxide has a layer thickness of 5 nm and a lateral size of 66 μm.

[0086] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of the invention herein is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the inventive concept. For example, the above-mentioned features may have similar functions to (but not limited to) those disclosed in this application.

Claims

1. A method for preparing graphene oxide, characterized in that: The following steps are involved: Step 1: placing concentrated sulfuric acid into a low-temperature constant-temperature container and maintaining the concentrated sulfuric acid at a first temperature; s2: turning on the magnetic field passing through the cryostat container by an electromagnetic device provided in the cryostat container; S3: Then add graphite raw material to concentrated sulfuric acid, and then add potassium permanganate; S4: Control the temperature of concentrated sulfuric acid to the first temperature and maintain it for 0.5-4h; S5: Raise the temperature of concentrated sulfuric acid to the second temperature and keep it at the second temperature for 0.5-1h; s6: then repeat steps s4 and s5 several times in sequence to obtain a first reaction solution; s7: heating the first reaction solution to a third temperature and maintaining the temperature at the third temperature for 1-6 hours to obtain a second reaction solution; S8: Deionized water was added to the second reaction solution, followed by a 30% by mass hydrogen peroxide solution with continuous stirring to obtain a bright yellow solution; s9: The bright yellow solution is precipitated, washed, and dried to obtain a black graphene oxide dispersion.

2. The method for preparing graphene oxide according to claim 1, wherein The mass ratio of concentrated sulfuric acid, graphite raw material and potassium permanganate in s3 is (18.4-110.4): (1-10): (1.5-9).

3. The method for preparing graphene oxide according to claim 1, wherein The first temperature is -5 to -1°C.

4. The method for preparing graphene oxide according to claim 1, wherein The second temperature is 10-35°C.

5. The method for preparing graphene oxide according to claim 1, wherein In step s6, steps s4 and s5 are repeated 3-4 times in sequence to obtain a first reaction solution.

6. The method for preparing graphene oxide according to claim 1, wherein In steps s 3–s 5, the magnetic field strength is 0.01–0.025 Tesla; When steps s4 and s5 are repeated in step s6, the magnetic field strength is reduced.

7. The method for preparing graphene oxide according to claim 1, wherein The third temperature is 78-80°C.

8. The method for preparing graphene oxide according to claim 1, wherein In step s8, the mass ratio of the hydrogen peroxide solution to the graphite raw material is (5.5-33): (1-10); The concentration of the hydrogen peroxide solution is 30%.

9. The method for preparing graphene oxide according to claim 1, wherein The graphite raw material includes one of flake graphite, expanded graphite and vermicular graphite.

10. The method for preparing graphene oxide according to claim 1, wherein The low-temperature constant temperature container includes a accommodating chamber with an upper opening, and a first accommodating space sleeved outside the side wall of the accommodating chamber. A first temperature control medium is provided in the first accommodating space, and the first temperature control medium is ethanol. The first accommodating space is provided with a first liquid inlet and a first liquid outlet. The first liquid inlet is connected to the first temperature control medium constant temperature storage tank through a first circulation pump. A second accommodating space is provided at the bottom of the accommodating cavity, and a second temperature-control medium is provided in the second accommodating space, and the second temperature-control medium is water; the second accommodating space is provided with a second liquid inlet and a second liquid outlet, and the second liquid inlet is connected to the second temperature-control medium constant temperature storage tank through a second circulation pump; An electromagnetic device is provided on the inner side wall of the accommodating cavity or the outer side wall of the first accommodating space; When the temperature of the concentrated sulfuric acid is controlled at the first temperature in step s4, the second temperature control medium in the second accommodating space is emptied, and the first circulation pump is turned on to circulate the first temperature control medium in the first accommodating space; the temperature of the first temperature control medium is -5 to -1°C; When the temperature of the concentrated sulfuric acid is controlled to the second temperature in step s5, the first temperature control medium in the first accommodating space is emptied, and the second circulation pump is turned on to circulate the second temperature control medium in the second accommodating space; the temperature of the second temperature control medium is 10 to 35°C.