CN115028163A - Preparation method of highly fluorinated graphene - Google Patents

Preparation method of highly fluorinated graphene Download PDF

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CN115028163A
CN115028163A CN202210716154.5A CN202210716154A CN115028163A CN 115028163 A CN115028163 A CN 115028163A CN 202210716154 A CN202210716154 A CN 202210716154A CN 115028163 A CN115028163 A CN 115028163A
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fluorinated graphene
reaction
ultrasonic
graphene
graphene oxide
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欧宝立
彭怡和
牛博
彭勇洁
李锦轩
杨肖
朱萍
陈丽娟
田俐
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Hunan University of Science and Technology
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Hunan University of Science and Technology
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    • C—CHEMISTRY; METALLURGY
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    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/194—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/198—Graphene oxide
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids

Abstract

The invention discloses a preparation method of highly fluorinated graphene, which comprises the following steps: s1, preparing graphene oxide by improving a Hummer method; s2, mixing graphene oxide, deionized water, hydrofluoric acid and potassium permanganate, performing ultrasonic dispersion, then placing the mixture in an ultrasonic-hydrothermal reaction kettle, and performing ultrasonic-hydrothermal coupling reaction at the ultrasonic frequency of 5-40 KHz and the hydrothermal temperature of 120-180 ℃; and S3, after the reaction is finished, centrifugally separating, washing and drying the reaction mixed liquid to obtain the fluorinated graphene. According to the preparation method, the graphene oxide is used as a raw material, the potassium permanganate and the hydrofluoric acid are used as fluorinating agents, and the ultrasonic dispersion and ultrasonic-hydrothermal coupling technology is combined to prepare the high-degree fluorinated graphene.

Description

Preparation method of highly fluorinated graphene
Technical Field
The invention relates to the technical field of organic semiconductor materials, in particular to a preparation method of highly fluorinated graphene.
Background
Fluorinated graphene can be regarded as graphene partially or fully fluorinated, sp in graphite 2 The structure being partly or wholly converted to sp 3 But still maintains a sheet-like structure and is the thinnest insulator, known as two-dimensional polytetrafluoroethylene. The fluorinated graphene has the advantages of two materials of graphene and polytetrafluoroethylene, has the chemical stability and high temperature resistance of the polytetrafluoroethylene, and can be used for producing products such as non-stick pans, sealing gaskets and the like; meanwhile, the original honeycomb carbon-carbon skeleton structure of graphene is reserved, the excellent performance of a plurality of graphene is inherited, fluorine atoms on fluorinated graphene exist in a C-F covalent bond mode, the introduction of the fluorine atoms brings novel interface and physicochemical properties such as surface energy reduction, hydrophobicity enhancement, band gap broadening and the like, and the quality change span from a semiconductor to an insulator can be realized by regulating and controlling the content of fluorine elements in the fluorinated graphene. The fluorinated graphene has excellent lubricating property, is superior to general graphite and molybdenum disulfide, and has smaller friction coefficient and longer service life when being dried or wetted at high temperature (400-500 ℃). Due to the combination of the advantages of the two aspects, the fluorinated graphene has wide application prospects in various fields such as wear resistance and lubrication, capacitance power supplies, electronic devices, electronic packaging and the like.
According to different carbon source materials of the fluorinated graphene, the preparation method of the fluorinated graphene is summarized into the following three methods: a graphene fluorination method, a graphite fluoride exfoliation method, and a graphene oxide fluorination method. The method comprises the following steps of preparing fluorinated graphene by reacting fluorine gas or xenon difluoride serving as a fluorination reagent with graphene, wherein the fluorination reagent used in the method is extremely toxic and expensive, and meanwhile, high-temperature and high-pressure equipment is involved, so that the operation process is complex and the risk is high; the graphite fluoride stripping method is to strip graphite fluoride serving as a raw material by using an organic solvent or an ionic liquid to prepare the graphene fluoride, the graphene fluoride obtained by the method cannot be accurately controlled in lamellar layers, and the lamellar layers are more, meanwhile, due to the hydrophobicity of the graphite fluoride, the surface wettability of the graphite fluoride is poor, concentrated sulfuric acid or mixed acid (sulfuric acid, nitric acid, hydrochloric acid and the like) and chemical reagents such as an oxidant are difficult to completely contact with the graphite fluoride to fully influence the reaction degree, so that the product quality and the performance of the graphene fluoride are poor, for example, the preparation methods of the fluorinated graphene oxide disclosed in chinese patent CN107867684B and chinese patent CN 107867684B; the graphene oxide fluorination method is to react graphene oxide with a fluorine-containing reagent under certain conditions, and as a plurality of-OH, -COOH and-C-O-C-oxygen-containing groups exist on the surface of the graphene oxide, the oxygen-containing groups can provide reactive sites for fluorination and help fluorine atoms in a fluorinating agent to replace the oxygen-containing groups in the graphene oxide to generate C-F covalent bonds, so that the fluorinated graphene is obtained. For example, chinese patent CN107879328A discloses a method for preparing water-dispersible fluorinated graphene, but the fluorinated graphene prepared by the method has a low fluorine content (0.5-5.0%) and a structure thereof is easily damaged. In view of this, the invention provides a preparation method of highly fluorinated graphene with high fluorine content and good dispersion stability in water.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a preparation method of highly fluorinated graphene, so as to solve the technical problems that the fluorinated graphene prepared by the existing method is low in fluorine content and poor in dispersion stability in water.
In order to achieve the above object, the present invention adopts the following technical solutions.
A preparation method of highly fluorinated graphene comprises the following steps:
s1, preparing graphene oxide by improving a Hummer method;
s2, mixing graphene oxide, deionized water, hydrofluoric acid and potassium permanganate, performing ultrasonic dispersion, then placing the mixture in an ultrasonic-hydrothermal reaction kettle, and performing ultrasonic-hydrothermal coupling reaction at the ultrasonic frequency of 5-40 KHz and the hydrothermal temperature of 120-180 ℃;
and S3, after the reaction is finished, post-treating the reaction mixed liquid to obtain the fluorinated graphene.
Preferably, in step S2, the specific steps of the ultrasonic-hydrothermal coupling reaction are: the method comprises the steps of firstly reacting for 1-5 hours under the conditions that the hydrothermal temperature is 120-150 ℃ and the ultrasonic frequency is 5-25 KHz, then adjusting the hydrothermal temperature to 150-180 ℃ and the ultrasonic frequency to 25-40 KHz, and continuing to react for 15-25 hours.
Preferably, in step S2, the concentration of the hydrofluoric acid is 30% to 45%, and the ratio of the graphene oxide to the hydrofluoric acid to the potassium permanganate is 100 mg: 5-8 ml: 280-550 mg.
Preferably, in step S2, the graphene oxide, deionized water, hydrofluoric acid, and potassium permanganate are mixed and ultrasonically dispersed, and the specific steps are as follows: firstly, graphene oxide is ultrasonically dispersed into deionized water to obtain a graphene oxide dispersion liquid, then a mixed solution of hydrofluoric acid and potassium permanganate is added into the graphene oxide dispersion liquid to continue to be ultrasonically dispersed uniformly, and a graphene oxide mixed liquid is obtained, wherein the concentration of the graphene oxide dispersion liquid is 1-2 mg/mL.
Preferably, in step S2, the ultrasonic frequency of the ultrasonic dispersion is 30 to 60kHz, and the ultrasonic intensity is 0.6 to 1.0W/cm 2 And the ultrasonic time is 30-60 min.
Preferably, the graphene oxide is prepared by improving a Hummer method.
Preferably, the graphene oxide is prepared according to the following steps: adding the crystalline flake graphite and sodium nitrate into concentrated sulfuric acid, performing ultrasonic mixing, keeping the mixture in a cold water bath at the temperature of 0-5 ℃ for reaction for 1-2 hours, then adding potassium permanganate, and continuing to keep the reaction in the cold water bath at the temperature of 0-5 ℃ for 3-5 hours; and then placing the reaction system in a water bath at 35-45 ℃ for continuous reaction for 0.5-1 h, adding deionized water into the reaction system, raising the temperature of the water bath to 95-98 ℃ for continuous reaction for 0.5-1 h, after the reaction is finished, adding 25-35 wt% of hydrogen peroxide solution into the reaction system, carrying out centrifugal separation treatment to obtain a supernatant and a lower precipitate, repeatedly washing the lower precipitate, centrifuging until the pH value of the upper supernatant is neutral, and drying to obtain the graphene oxide.
Preferably, the proportion of the crystalline flake graphite, the sodium nitrate, the concentrated sulfuric acid, the potassium permanganate, the hydrogen peroxide and the deionized water is 1-6 g: 0.5-3 g: 40-60 ml: 6-15 g: 3-8 ml: 80-120 ml.
The second objective of the present invention is to provide the fluorinated graphene prepared by the above preparation method.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the invention, graphene oxide is used as a carbon source material for preparing fluorinated graphene, and as a plurality of-OH, -COOH and-C-O-C-oxygen-containing groups exist on the surface of the graphene oxide, the oxygen-containing groups can provide reactive sites for fluorination reaction, and compared with other carbon source materials, a large number of reactive sites exist on the surface of the graphene oxide, the surface functionalization of the graphene oxide is easier; in the hydrothermal reaction process, graphene oxide is reduced to a certain degree by hydrofluoric acid due to high temperature and high pressure in the hydrothermal condition, that is, oxygen-containing groups on the surface of graphene oxide are removed to a certain degree, so that reactive sites are reduced, the progress of a fluorination reaction is hindered, and the fluorination degree is greatly reduced. In the hydrothermal reaction process, a proper amount of potassium permanganate (potassium permanganate has strong oxidizing property in an acid environment) is added, so that the existence of the potassium permanganate in the system can effectively prevent the oxidized graphene and high-concentration hydrofluoric acid from reacting to generate precipitate under the hydrothermal condition, the oxygen-containing group of the oxidized graphene can be ensured to be kept as much as possible, and even more active groups are further generated on the surface of the oxidized graphene through the oxidation effect of the oxygen-containing group, so that more reactive active sites are provided for fluorination, and the fluorinated graphene with high fluorine content is obtained.
(2) According to the invention, the highly fluorinated graphene is prepared by combining ultrasonic dispersion with ultrasonic-hydrothermal coupling reaction, specifically, firstly, the graphene oxide is fully and uniformly dispersed in a mixed solution of hydrofluoric acid and potassium permanganate by ultrasonic treatment, so that the self-assembly and aggregation of the graphene oxide in a hydrothermal reaction system can be prevented, and the reaction uniformity of the hydrofluoric acid, the potassium permanganate and the graphene oxide in the subsequent hydrothermal reaction process is ensured; then, placing the graphene oxide mixed solution obtained after ultrasonic dispersion in an ultrasonic-hydrothermal coupling reaction kettle, and carrying out hydrothermal reaction in two stages: in the low-temperature hydrothermal stage, the graphene oxide is subjected to primary fluorination, and under the low-temperature low-frequency ultrasonic condition, hydrofluoric acid and potassium permanganate serving as fluorinating agents can fully react with active groups on the surface of the graphene oxide, so that the fluorination degree of the fluorinating agents is improved, and meanwhile, potassium permanganate can further generate more active groups on the surface of the graphene oxide through the oxidation effect of the potassium permanganate, so that more reactive sites are provided for the fluorination reaction in the subsequent high-temperature hydrothermal stage; and in the high-temperature hydrothermal stage, the graphene oxide is subjected to deep fluorination, the high-efficiency fluorination reaction can be promoted under the dual actions of high-frequency ultrasound and high-temperature synergy, the fluorination degree of the fluorinated graphene is further improved, and the highly fluorinated graphene is obtained through centrifugation, washing and drying. According to the method, the fluorinated graphene is prepared by utilizing ultrasonic dispersion and ultrasonic-hydrothermal coupling reaction, so that the preparation time can be effectively saved, the energy can be saved, the rich content of the fluorinated graphene can be effectively improved, and the quality of a fluorinated graphene product can be further improved.
(3) According to the invention, the mixed solution of hydrofluoric acid and potassium permanganate with a specific proportion and dosage is used as the fluorinating agent, so that graphene oxide can be fully fluorinated to the maximum extent without damaging the structure of the graphene oxide, and F used in conventional fluorinated graphene production is avoided 2 Or XeF 2 And the like, which are strong corrosive and high-risk fluorination reagents. In addition, the graphene oxide is prepared by using crystalline flake graphite as a raw material, and is rich in source and low in cost.
(4) The preparation method has the advantages of simple process, low cost, no toxicity, environmental friendliness and easiness in realizing large-scale production. And the prepared fluorinated graphene has high fluorine content and good dispersion stability in water.
Drawings
Fig. 1 is an infrared spectrum of graphene oxide and graphene fluoride prepared in example 1 of the present invention. Wherein GO represents graphene oxide, none-FG represents the KMnO, fluorinated graphene prepared without potassium permanganate in the hydrothermal reaction process 4 FG represents fluorinated graphene prepared by adding potassium permanganate in the hydrothermal reaction process;
FIG. 2 is an X Photoelectron Spectroscopy (XPS) chart of fluorinated graphene prepared in example 1 of the present invention;
fig. 3 is an SEM electron micrograph of fluorinated graphene prepared in example 1 of the present invention;
FIG. 4 shows different degrees of fluorination R prepared in examples 1-4 of the present invention C/F A real figure of fluorinated graphene of (1).
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to specific embodiments, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments.
Example 1
A preparation method of highly fluorinated graphene comprises the following specific steps:
s1, preparing graphene oxide by improving a Hummer method, namely weighing 2g of crystalline flake graphite and 1g of sodium nitrate, adding the crystalline flake graphite and the sodium nitrate into a beaker filled with 46ml of concentrated sulfuric acid (the mass fraction is 95-98%), ultrasonically mixing for 10min, and placing the mixture in a cold water bath at 0-5 ℃ for continuous magnetic stirring reaction for 2 h; then slowly adding 9g of potassium permanganate for multiple times under the action of magnetic stirring, finishing the addition within 3 hours, and then continuing the magnetic stirring reaction for 2 hours; then raising the temperature of the water bath to 40 ℃, continuing to react for 0.5h by magnetic stirring, adding 100ml of deionized water, continuing to raise the temperature of the water bath to 98 ℃, continuing to react for 0.5h by magnetic stirring, adding 3ml of 30 wt% hydrogen peroxide solution into the beaker under the action of magnetic stirring, standing for layering, taking the sediment at the lower layer, repeatedly washing and centrifuging the sediment at the lower layer by using deionized water, and keeping the pH value of the supernatant neutral; drying the treated lower-layer precipitate in a vacuum drying oven at 70 ℃ to obtain graphene oxide;
s2, adding 100mg of graphene oxide and 50ml of deionized water into a polytetrafluoroethylene beaker, and carrying out ultrasonic treatment at an ultrasonic frequency of 40kHz and a frequency of 0.8W/cm 2 Ultrasonic dispersing for 20min to obtain graphene oxideDispersing, then adding 5ml of mixed solution of 40 wt% hydrofluoric acid and 300mg potassium permanganate into the graphene oxide dispersion, and performing ultrasonic treatment at 50kHz and 1.0W/cm 2 After ultrasonic dispersion for 20min, transferring the mixture into an ultrasonic-hydrothermal reaction kettle with a polytetrafluoroethylene lining, firstly reacting for 3h under the conditions that the hydrothermal temperature is 130 ℃ and the ultrasonic frequency is 15KHz, then adjusting the hydrothermal temperature to 180 ℃ and the ultrasonic frequency to 35KHz, and continuing to react for 20 h;
and S3, after the hydrothermal reaction is finished, centrifugally separating and washing the mixed reaction solution until the pH value is neutral, and drying to obtain the fluorinated graphene.
And (3) characterization results: as shown in FIG. 1, the IR spectrum of the fluorinated graphene prepared in example 1 is 1000cm -1 ～1250cm -1 A stretching vibration absorption peak of a C-F bond appears, which indicates that the preparation method successfully prepares the fluorinated graphene. As shown in fig. 2, X Photoelectron Spectroscopy (XPS) is used to determine that 39.83% of carbon atoms and 42.33% of fluorine atoms are present in the fluorinated graphene prepared in example 1, which results in the degree of fluorination R of the fluorinated graphene prepared in example 1 C/F The value is 0.94, which shows that the fluorinated graphene prepared by the method has higher fluorine content. As shown in fig. 3, which is an SEM image of the fluorinated graphene prepared in example 1, the SEM image shows that the fluorinated graphene prepared in example 1 has good surface structure retention, i.e., the structure is hardly damaged. The fluorinated graphene prepared in example 1 is dispersed in water for a dispersion experiment, and the test result shows that: the prepared fluorinated graphene is dispersed in water to prepare a fluorinated graphene aqueous dispersion solution with the concentration of 2mg/ml, the fluorinated graphene aqueous dispersion solution can be stably dispersed without adding any dispersant, and no obvious layering or precipitation phenomenon is found after standing for one week, which indicates that the fluorinated graphene prepared in the embodiment 1 has good dispersion stability.
Example 2
This example 2 is substantially the same as example 1 except that: in this embodiment 2, "400 mg of potassium permanganate" and "mentioned in step S2 are set to react for 2 hours under the conditions that the hydrothermal temperature is 120 ℃ and the ultrasonic frequency is 20KHz, then the hydrothermal temperature is adjusted to 180 ℃ and the ultrasonic frequency is 35KHz, and the reaction is continued for 25 hours; "replace" 300mg potassium permanganate "and" set up to react for 3 hours under the hydrothermal temperature of 130 ℃ and the ultrasonic frequency of 15KHz "in step S2 in example 1, then adjust the hydrothermal temperature to 180 ℃ and the ultrasonic frequency of 25KHz, continue to react for 18 hours; ", to obtain the fluorinated graphene.
X Photoelectron Spectroscopy (XPS) is used to determine that carbon atoms account for 35.24% and fluorine atoms account for 45.22% in the fluorinated graphene prepared in this example 2, i.e., the fluorination degree R of the fluorinated graphene prepared in this example 2 is obtained C/F The value is 0.78, which shows that the fluorinated graphene prepared in the example 2 has a high fluorine content. The fluorinated graphene prepared in example 2 is dispersed in water for a dispersion experiment, and the test result shows that: the prepared fluorinated graphene is dispersed in water to prepare a fluorinated graphene aqueous dispersion solution with the concentration of 2mg/ml, the fluorinated graphene aqueous dispersion solution can be stably dispersed without adding any dispersant, and no obvious layering or precipitation phenomenon is found after standing for one week, which indicates that the fluorinated graphene prepared in the embodiment 2 has good dispersion stability.
Example 3
This example 3 is substantially the same as example 1 except that: in this embodiment 3, the "500 mg potassium permanganate" and "set in the step S2 to react for 4 hours under the conditions that the hydrothermal temperature is 150 ℃ and the ultrasonic frequency is 5KHz, then the hydrothermal temperature is adjusted to 180 ℃ and the ultrasonic frequency is 35KHz, and the reaction is continued for 15 hours; "replaces the" 300mg potassium permanganate "in the step S2 in the embodiment 1 and" firstly reacts for 3 hours under the conditions that the hydrothermal temperature is 130 ℃ and the ultrasonic frequency is 15KHz, then the hydrothermal temperature is adjusted to 180 ℃ and the ultrasonic frequency is 35KHz, and the reaction is continued for 20 hours; ", obtaining the fluorinated graphene.
X Photoelectron Spectroscopy (XPS) is used to determine that 34.99% of carbon atoms and 47.03% of fluorine atoms are present in the fluorinated graphene prepared in this example 3, which means that the degree of fluorination R of the fluorinated graphene prepared in this example 3 is obtained C/F 0.74, indicating that the fluorinated graphene prepared in this example 3 has a high fluorine content. Dispersing the fluorinated graphene prepared in example 3 inThe dispersibility experiment is carried out in water, and the test result shows that: the prepared fluorinated graphene is dispersed in water to prepare a fluorinated graphene aqueous dispersion solution with the concentration of 2mg/ml, the fluorinated graphene aqueous dispersion solution can be stably dispersed without adding any dispersant, and no obvious layering or precipitation phenomenon is found after standing for one week, which indicates that the fluorinated graphene prepared by the preparation method of the embodiment 3 has good dispersion stability.
Example 4
This example 4 is substantially the same as example 1 except that: "at 30kHz ultrasonic frequency, 1.0W/cm in step S2 in example 4 2 Ultrasonic dispersion for 25min at an ultrasonic frequency of 60kHz and 0.8W/cm 2 Ultrasonic dispersion of ultrasonic intensity of (1) for 30min, 0.8W/cm at an ultrasonic frequency of 40kHz instead of the ultrasonic intensity described in step S2 of example 1 2 Ultrasonic dispersion for 20min at an ultrasonic frequency of 50kHz and 1.0W/cm 2 And ultrasonically dispersing for 20min by using the ultrasonic intensity to obtain the fluorinated graphene.
X-ray photoelectron spectroscopy (XPS) shows that 40.96% of carbon atoms and 41.82% of fluorine atoms in the fluorinated graphene prepared in this example 4 result in the degree of fluorination R of the fluorinated graphene prepared in this example 4 C/F The value is 0.98, which indicates that the fluorinated graphene prepared in the embodiment 4 has a higher fluorine content. As shown in FIG. 4, the different degrees of fluorination R prepared according to the present invention C/F As can be seen from the results in fig. 4, the actual graphs of the fluorinated graphene of (a) show that the degree of fluorination differs and the apparent color of the fluorinated graphene also differs. The fluorinated graphene prepared in example 4 is dispersed in water for a dispersion experiment, and the test result shows that: the prepared fluorinated graphene is dispersed in water to prepare a fluorinated graphene aqueous dispersion solution with the concentration of 2mg/ml, the fluorinated graphene aqueous dispersion solution can be stably dispersed without adding any dispersant, and no obvious layering or precipitation phenomenon is found after standing for one week, which indicates that the fluorinated graphene prepared in the embodiment 4 has good dispersion stability.
Example 5
This example 5 is substantially the same as example 1 except that: in this embodiment 5, the scale graphite 5g and the sodium nitrate 3g, which are described in step S1, are added into a beaker containing concentrated sulfuric acid 58ml, mixed by ultrasound for 15min, and then placed in a cold water bath at 0-5 ℃ for continuous magnetic stirring reaction for 2 hours; then slowly adding 15g of potassium permanganate for multiple times under the action of magnetic stirring, finishing the addition within 4 hours, and then continuing the magnetic stirring reaction for 3 hours; then raising the temperature of the water bath to 40 ℃, continuing to perform magnetic stirring reaction for 0.5h, adding 120ml of deionized water instead of 2g of flake graphite and 1g of sodium nitrate in step S1 in the embodiment 1 into a beaker containing 46ml of concentrated sulfuric acid, performing ultrasonic mixing for 10min, and placing in a cold water bath at 0-5 ℃ to perform continuous magnetic stirring reaction for 2 h; slowly adding 9g of potassium permanganate into the solution for multiple times under the action of magnetic stirring, finishing the addition within 3 hours, and continuing to react for 2 hours under the action of magnetic stirring; and then raising the temperature of the water bath to 40 ℃, continuing to perform magnetic stirring reaction for 0.5h, and then adding 100ml of deionized water to obtain the fluorinated graphene.
X Photoelectron Spectroscopy (XPS) was performed to determine that 39.97% of the carbon atoms and 42.95% of the fluorine atoms in the fluorinated graphene prepared in this example 5, which resulted in the R of the fluorinated graphene prepared in this example 5 C/F The value is 0.93, which shows that the fluorinated graphene prepared by the method has higher fluorine content. The dispersion experiment of the fluorinated graphene prepared in example 5 in water shows that: the prepared fluorinated graphene is dispersed in water to prepare a fluorinated graphene aqueous dispersion solution with the concentration of 2mg/ml, the fluorinated graphene aqueous dispersion solution can be stably dispersed without adding any dispersing agent, and no obvious layering or precipitation phenomenon is found after standing for one week, which shows that the fluorinated graphene prepared by the preparation method disclosed by the invention has good dispersion stability.
Comparative example 1
This comparative example 1 is essentially the same as example 1, except that: in comparative example 1, "0 mg potassium permanganate" in step S2 and in place of "300 mg potassium permanganate" in step S2 in example 1, fluorinated graphene was obtained.
The content of carbon atoms in the fluorinated graphene prepared in comparative example 1 was 81.09% and the content of fluorine atoms in the fluorinated graphene prepared in comparative example 1 was 2.02%, as measured by X Photoelectron Spectroscopy (XPS), i.e., R of the fluorinated graphene prepared in comparative example 1 C/F 41.14, indicating that this comparative example 1 was preparedThe fluorine content of the fluorinated graphene is low. The fluorinated graphene prepared in the comparative example 1 is dispersed in water for a dispersion experiment, and the test result shows that: the prepared fluorinated graphene is dispersed in water to prepare a fluorinated graphene aqueous dispersion solution with the concentration of 2mg/ml, and obvious layering and precipitation phenomena can be seen after standing for 24 hours under the condition of not adding any dispersant.
Comparative example 2
This comparative example 2 is essentially the same as example 1, except that: in the comparative example 2, "100 mg of potassium permanganate" and "a common hydrothermal reaction kettle" in the step S2, the hydrothermal temperature is 180 ℃, and the reaction time is 23 hours "instead of" 300mg of potassium permanganate "and" an ultrasonic-hydrothermal reaction kettle "in the step S2 in the example 1, so that the fluorinated graphene is obtained.
The content of carbon atoms in the fluorinated graphene prepared in the comparative example 2 is 73.52% and the content of fluorine atoms in the fluorinated graphene is 10.64% as measured by X Photoelectron Spectroscopy (XPS), and the R of the fluorinated graphene prepared in the comparative example 2 is obtained C/F The fluorine content of the fluorinated graphene prepared in the comparative example 2 is lower than that of the fluorinated graphene prepared in the comparative example 2, and the dispersion experiment performed by dispersing the fluorinated graphene prepared in the comparative example 2 in water shows that: the prepared fluorinated graphene is dispersed in water to prepare a fluorinated graphene aqueous dispersion solution with the concentration of 2mg/ml, and obvious layering and precipitation phenomena can be seen after standing for 24 hours under the condition of not adding any dispersant.
Comparative example 3
This comparative example 3 is essentially the same as example 1, except that: in this comparative example 3, "100 mg of potassium permanganate" in step S2 replaced "300 mg of potassium permanganate" described in step S2 in example 1, to obtain fluorinated graphene.
The content of carbon atoms in the fluorinated graphene prepared in the comparative example 3 is 57.69% and the content of fluorine atoms in the fluorinated graphene is 25.15% as measured by X Photoelectron Spectroscopy (XPS), that is, the R of the fluorinated graphene prepared in the comparative example 3 is obtained C/F The value is 2.29, which indicates that the fluorine content of the prepared fluorinated graphene is low. The fluorinated graphene prepared in comparative example 3 is dispersed in water to prepare a fluorinated graphene aqueous dispersion with the concentration of 2mg/ml, and the fluorinated graphene aqueous dispersion is allowed to stand for 24 hours without adding any dispersantSignificant delamination and settling were observed.
Comparative example 4
This comparative example 4 is essentially the same as example 1, except that: in comparative example 4, "200 mg of potassium permanganate" and "10 ml of 20 wt% hydrofluoric acid" in step S2 replace "300 mg of potassium permanganate" and "5 ml of 40 wt% hydrofluoric acid" in step S2 in example 1, respectively, to obtain fluorinated graphene.
The content of carbon atoms in the fluorinated graphene prepared in the comparative example 4 was 48.96% and the content of fluorine atoms in the fluorinated graphene was 34.84% as measured by X-ray photoelectron spectroscopy (XPS), and R of the fluorinated graphene prepared in the comparative example 4 was obtained C/F The value is 1.40, which indicates that the fluorine content of the prepared fluorinated graphene is low. The fluorinated graphene prepared in the comparative example 4 is dispersed in water to prepare a fluorinated graphene aqueous dispersion solution with the concentration of 2mg/ml, and obvious layering phenomenon can be seen after standing for 24 hours under the condition of not adding any dispersant.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (8)

1. A preparation method of highly fluorinated graphene is characterized by comprising the following steps:
s1, preparing graphene oxide by improving a Hummer method;
s2, mixing graphene oxide, deionized water, hydrofluoric acid and potassium permanganate, performing ultrasonic dispersion, then placing the mixture in an ultrasonic-hydrothermal reaction kettle, and performing ultrasonic-hydrothermal coupling reaction at the ultrasonic frequency of 5-40 KHz and the hydrothermal temperature of 120-180 ℃;
and S3, after the reaction is finished, carrying out post-treatment on the reaction mixed liquid to obtain the fluorinated graphene.
2. The method for preparing highly fluorinated graphene according to claim 1, wherein in step S2, the specific steps of the ultrasonic-hydrothermal coupling reaction are as follows: the method comprises the steps of firstly reacting for 1-5 hours under the conditions that the hydrothermal temperature is 120-150 ℃ and the ultrasonic frequency is 5-25 KHz, then adjusting the hydrothermal temperature to 150-180 ℃ and the ultrasonic frequency to 25-40 KHz, and continuing to react for 15-25 hours.
3. The method for preparing highly fluorinated graphene according to claim 1, wherein in step S2, the concentration of hydrofluoric acid is 30% to 45%, and the ratio of graphene oxide to hydrofluoric acid to potassium permanganate is 100 mg: 5-8 ml: 280-550 mg.
4. The method for preparing highly fluorinated graphene according to claim 1, wherein in step S2, the graphene oxide, deionized water, hydrofluoric acid and potassium permanganate are mixed and ultrasonically dispersed, and the method comprises the following specific steps: firstly, ultrasonically dispersing graphene oxide into deionized water to obtain a graphene oxide dispersion liquid, then adding a mixed solution of hydrofluoric acid and potassium permanganate into the graphene oxide dispersion liquid, and continuously and uniformly ultrasonically dispersing to obtain a graphene oxide mixed liquid, wherein the concentration of the graphene oxide dispersion liquid is 1-2 mg/mL.
5. The method for preparing highly fluorinated graphene according to claim 1, wherein in step S2, the ultrasonic dispersion has an ultrasonic frequency of 30 to 60kHz and an ultrasonic intensity of 0.6 to 1.0W/cm 2 And the ultrasonic time is 30-60 min.
6. The method for preparing highly fluorinated graphene according to claim 1, wherein in step S1, the graphene oxide is prepared by the following steps: adding the crystalline flake graphite and sodium nitrate into concentrated sulfuric acid, performing ultrasonic mixing, keeping the mixture in a cold water bath at the temperature of 0-5 ℃ for reaction for 1-2 hours, then adding potassium permanganate, and continuing to keep the reaction in the cold water bath at the temperature of 0-5 ℃ for 3-5 hours; and then placing the reaction system in a water bath at 35-45 ℃ for continuous reaction for 0.5-1 h, adding deionized water into the reaction system, raising the temperature of the water bath to 95-98 ℃ for continuous reaction for 0.5-1 h, after the reaction is finished, adding 25-35 wt% of hydrogen peroxide solution into the reaction system, performing centrifugal separation treatment to obtain a supernatant and a lower precipitate, repeatedly washing the lower precipitate, centrifuging until the pH value of the upper supernatant is neutral, and drying to obtain graphene oxide.
7. The method for preparing highly fluorinated graphene according to claim 6, wherein the ratio of crystalline flake graphite, sodium nitrate, concentrated sulfuric acid, potassium permanganate, hydrogen peroxide to deionized water is 1-6 g: 0.5-3 g: 40-60 ml: 6-15 g: 3-8 ml: 80-120 ml.
8. Fluorinated graphene prepared by the preparation method according to any one of claims 1 to 7.
CN202210716154.5A 2022-06-23 2022-06-23 Preparation method of highly fluorinated graphene Pending CN115028163A (en)

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US20130237723A1 (en) * 2010-12-22 2013-09-12 Mingjie Zhou Fluorinated graphene oxide and preparation method thereof
CN104860289A (en) * 2015-04-22 2015-08-26 湖南元素密码石墨烯研究院（有限合伙） Method for preparing fluorinated graphene
CN105967175A (en) * 2016-05-16 2016-09-28 河南工业大学 Preparation method of water-soluble fluorinated graphene
CN206103910U (en) * 2016-09-30 2017-04-19 华南理工大学 Hydrothermal reaction vessel that can add ultrasonic field

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US20130237723A1 (en) * 2010-12-22 2013-09-12 Mingjie Zhou Fluorinated graphene oxide and preparation method thereof
CN102502828A (en) * 2011-11-23 2012-06-20 陕西科技大学 Preparation method for V2O5 nanometer crystals
CN104860289A (en) * 2015-04-22 2015-08-26 湖南元素密码石墨烯研究院（有限合伙） Method for preparing fluorinated graphene
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