A method for preparing graphene

Abstract

The application provides a preparation method of graphene, and belongs to the technical field of carbon material preparation. The application provides a preparation method of graphene, which comprises the following steps: mixing fluorinated salt, hydrogen fluoride solution and graphite, performing etching and peeling to obtain graphene; the etching and peeling is performed at a temperature of 10-40 DEG C for 70-75 h; the fluorinated salt comprises potassium hexafluorosilicate and potassium hexafluoromanganate; the solvent in the hydrogen fluoride solution is one or more of N-methyl pyrrolidone, methylamine, ethylamine and pyridine. The preparation method provided by the application is simple, has low energy consumption and low cost, and the prepared graphene has high purity; the application does not need to perform oxidation and reduction processes, reduces the mixing of impurities, and does not need high-temperature calcination. The application uses hydrogen fluoride instead of concentrated sulfuric acid in the oxidation-reduction method, and the acidic waste liquid is easy to recover.

Description

Technical Field

[0001] This invention belongs to the field of carbon material preparation technology, specifically relating to a method for preparing graphene. Background Technology

[0002] Graphene possesses excellent optical, electrical, and mechanical properties, and has significant application prospects in materials science, micro-nano fabrication, energy, biomedicine, and drug delivery. It is considered a revolutionary material for the future, and research and application development of graphene continues to heat up. Graphene-related materials are widely used in battery electrode materials, semiconductor devices, transparent displays, sensors, capacitors, transistors, and other fields.

[0003] The oxidation-reduction method is the easiest way to achieve large-scale industrial production of graphene. It involves oxidizing natural graphite using chemical reagents such as sulfuric acid and nitric acid, and oxidants such as potassium permanganate and hydrogen peroxide. However, this method uses strong acids such as sulfuric acid and nitric acid, posing significant risks, and requires large amounts of water for washing, resulting in substantial environmental pollution and making recycling difficult. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for preparing graphene. The preparation method provided by this invention uses hydrogen fluoride instead of concentrated sulfuric acid in the redox method, and the acidic waste liquid is easily recovered.

[0005] To achieve the above objectives, the present invention provides the following solution:

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

[0007] Graphene is obtained by mixing fluoride salts, hydrogen fluoride solution and graphite, followed by etching and exfoliation.

[0008] The etching and stripping temperature is 10–40°C, and the time is 70–75 h;

[0009] The fluoride salts include potassium hexafluorosilicate and potassium hexafluoromanganate;

[0010] The solvent in the hydrogen fluoride solution is one or more of N-methylpyrrolidone, methylamine, ethylamine, and pyridine.

[0011] Preferably, the mass ratio of potassium hexafluorosilicate to potassium hexafluoromanganate is 4:1.

[0012] Preferably, the mass ratio of the fluoride salt to graphite is 10:1.

[0013] Preferably, the hydrogen fluoride solution contains 20-80% hydrogen fluoride by mass.

[0014] Preferably, the solid content of the mixture obtained after mixing the fluoride salt, hydrogen fluoride solution, and graphite is 15-30%.

[0015] Preferably, the mass ratio of the fluoride salt to the volume ratio of the hydrogen fluoride solution is (12-120) g: 1 L.

[0016] Preferably, after the etching and stripping are completed, the resulting mixed slurry is cooled, then a dispersant is added, and then the mixture is subjected to centrifugation, washing, ultrasonic dispersion and drying in sequence.

[0017] Preferably, the cooling is to cool to 3-7°C.

[0018] Preferably, the dispersant comprises N-methyl-2-pyrrolidone.

[0019] Preferably, the mass ratio of the dispersant to the mass of the mixture obtained after mixing the fluoride salt, hydrogen fluoride solution and graphite is (10-20):1.

[0020] This invention provides a method for preparing graphene, comprising the following steps: mixing a fluoride salt, a hydrogen fluoride solution, and graphite, and then etching and exfoliating the mixture to obtain graphene; the etching and exfoliation temperature is 10–40°C, and the time is 70–75 h; the fluoride salt includes potassium hexafluorosilicate and potassium hexafluoromanganate; the solvent in the hydrogen fluoride solution is one or more of N-methylpyrrolidone, methylamine, ethylamine, and pyridine.

[0021] This invention uses a non-aqueous hydrogen fluoride liquid containing potassium hexafluorosilicate (denoted as the first fluoride complex) and potassium hexafluoromanganate (denoted as the second fluoride complex). Potassium hexafluoromanganate (K2MnF6) can provide Mn 4+ It also contains Mn 3+ In a strongly oxidizing environment, Mn 4+ It is the primary form in which Mn exists; however, in a relatively reducing environment, some Mn... 4+ It may be reduced to Mn 3+ This leads to Mn 4+ and Mn 3+ The coexistence of these substances. Organic amine solvents (such as methylamine, ethylamine, pyridine, etc.) release ammonium ions (NH4+) when reacting with water or under acidic conditions. + Therefore, alkali metal ions (such as potassium ions), ammonium ions, and tetravalent metal ions (such as Mn) coexist in the reaction system. 4+ Mn 4+ Acting as the primary strong oxidizing agent, it extracts electrons from the graphite surface, promoting the graphene exfoliation process. Alkali metal ions and ammonium ions, on the other hand, assist in charge balance and improve reaction efficiency.

[0022] The role of alkali metal ions (potassium ions):

[0023] Charge balance: In chemical reactions, potassium ions can help balance the charges in the reaction system, thereby stabilizing the entire system.

[0024] Assisted exfoliation: The interaction between potassium ions and graphene layers can help weaken the van der Waals forces between graphene layers, thus promoting the exfoliation of graphene.

[0025] ammonium ions (NH4) + The function of ) is:

[0026] Charge neutralization: Ammonium ions can neutralize some of the negative charge in the reaction system, helping to maintain the electroneutrality of the reaction environment.

[0027] Assisted exfoliation: Ammonium ions can enter the interlayer space of graphite, weakening the interlayer forces and thus facilitating the exfoliation of graphene.

[0028] trivalent manganese ions (Mn) 3+ The function of ) is:

[0029] Oxidation: Although Mn 3+ Its oxidizing power is greater than that of NH4 + Although weak, it can still play a certain role in oxidation, helping to oxidize graphite into graphite oxide.

[0030] Assisted oxidation reaction: During the reaction, Mn 3+ Can be used with NH4 + Synergistic effect promotes the oxidation reaction during the graphene exfoliation process.

[0031] In this invention, when electrons are extracted from the graphite surface, an electric charge accumulates on the surface of each graphene sheet, generating electrostatic repulsion. This electrostatic repulsion creates gaps between the originally tightly stacked graphite layers, facilitating the exfoliation of the graphite layers and yielding relatively intact graphene sheets. Compared to methods that directly oxidize graphite using strong oxidants, this invention eliminates the intermediate graphite oxidation process, allowing the direct extraction of fluorinated graphene from graphite. This significantly reduces structural defects generated during graphene exfoliation, such as vacancies and dangling bonds. The resulting graphene exhibits high structural integrity. Experimental results show that the fluorinated graphene obtained using this method has approximately five layers, indicating that the exfoliation process is relatively gentle and does not damage the graphene structure.

[0032] The preparation method provided by this invention is simple, energy-efficient, and low-cost, and produces high-purity graphene. This invention does not require oxidation and reduction processes, reducing the introduction of impurities, and also eliminates the need for high-temperature calcination.

[0033] This invention uses hydrogen fluoride instead of concentrated sulfuric acid in the redox process, making the acidic waste liquid easy to recover; while concentrated sulfuric acid is corrosive and has strong oxidizing properties, resulting in high costs for subsequent waste liquid treatment and making it difficult to recover.

[0034] This invention rationally selects the first fluoride complex and the second fluoride complex: the types of ions and metals in the first fluoride complex and the second fluoride complex are limited, avoiding the introduction of other impurity ions. This selectivity helps to control the impurity content in graphene and improve its purity.

[0035] The composition and preparation conditions of the hydrogen fluoride solution were precisely controlled: the hydrogen fluoride content was maintained between 20% and 80% by mass, providing a sufficient fluorine source without introducing excessive corrosive impurities. The organic solvents used to dissolve the hydrogen fluoride, such as heterocyclic compounds (pyridine) and amines (methylamine or ethylamine), were also strictly controlled within appropriate ranges. Optimization of process parameters such as temperature and stirring helped avoid side reactions. The post-processing was optimized: centrifugation and solvent washing effectively removed impurities remaining on the graphene surface, such as unreacted fluoride complexes. Finally, NMP solvent was used to disperse the graphene, further improving its purity.

[0036] In this invention, the fluorine content in the graphene is controlled at 1-20 atomic%, and the oxygen content is less than 5 atomic%. The fluorine to carbon atom ratio (F / C) is in the range of 0.01-0.3, indicating that the introduced fluorine atoms are controllable and will not be excessive.

[0037] The graphene produced by the method of this invention, due to its fluorine doping, can be used in semiconductor devices such as field-effect transistors and transparent conductive films, and can also be used in electronic sensors, transistors, batteries, fuel cells, solar cells, touch screens, display technologies, and other fields, including lighting. Furthermore, the graphene produced by the method of this invention can be used as a material for easily controlled semiconductor devices, a material for fluorine gas adsorbents, and a material for waterproofing agents.

[0038] Therefore, by precisely controlling the selection of raw materials, process conditions, and post-processing, this invention effectively avoids the introduction of impurities, resulting in graphene with high purity, which lays the foundation for the subsequent application of graphene. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a flowchart illustrating the preparation process of graphene according to the present invention.

[0041] Figure 2 This is a SEM image of Example 1;

[0042] Figure 3 The Raman spectrum and fitted spectrum of Example 1 are shown. Detailed Implementation

[0043] This invention provides a method for preparing graphene, comprising the following steps:

[0044] Graphene is obtained by mixing fluoride salts, hydrogen fluoride solution and graphite, followed by etching and exfoliation.

[0045] The etching and stripping temperature is 10–40°C, and the time is 70–75 h;

[0046] The fluoride salts include potassium hexafluorosilicate and potassium hexafluoromanganate;

[0047] The solvent in the hydrogen fluoride solution is one or more of N-methylpyrrolidone, methylamine, ethylamine, and pyridine.

[0048] Unless otherwise specified, all materials and equipment used in this invention are commercially available products.

[0049] In this invention, the mixing of fluoride salt, hydrogen fluoride solution and graphite preferably includes the following steps:

[0050] The fluoride salt and hydrogen fluoride solution are first mixed to obtain a stripping solution; then the stripping solution is second mixed with graphite.

[0051] In this invention, the fluoride salt preferably includes potassium hexafluorosilicate and potassium hexafluoromanganate; the mass ratio of potassium hexafluorosilicate to potassium hexafluoromanganate is preferably 4:1.

[0052] In this invention, the mass content of hydrogen fluoride in the hydrogen fluoride solution is preferably 20-80%.

[0053] In this invention, the preferred mass ratio of the fluoride salt to the volume ratio of the hydrogen fluoride solution is (12-120) g: 1 L, more preferably (20-100) g: 1 L, and even more preferably (50-80) g: 1 L.

[0054] In this invention, the hydrogen fluoride solution is used to provide a fluorine source: the hydrogen fluoride in the hydrogen fluoride solution of this invention provides the necessary fluorine element for the subsequent production of fluorinated graphene. Hydrogen fluoride can promote the exfoliation of graphene: when the non-aqueous hydrogen fluoride liquid comes into contact with graphite, the hydrogen fluoride reacts with the carbon atoms on the graphite surface. This reaction breaks the covalent bonds between carbon atoms, which is beneficial for the exfoliation of the graphene layer. It avoids damage to the graphene structure: compared with the method of directly oxidizing graphite with a strong oxidant, this invention does not require the step of oxidizing graphite. This avoids potential graphene structural defects caused during the oxidation process. It endows graphene with new properties: fluorinated graphene has new electronic structures and performance characteristics, and can be used in semiconductors, adsorption, and other fields. The introduction of fluorine brings tunable band gaps and other unique properties to graphene.

[0055] In this invention, the temperature of the first mixing is preferably 10–40°C, more preferably 20–30°C, and even more preferably 25°C; the time of the first mixing is preferably 70–75 h, and even more preferably 72 h. In this invention, the first mixing is preferably carried out under stirring conditions.

[0056] By controlling the temperature of the first mixing step at 10–40°C, this invention avoids excessive evaporation of hydrogen fluoride and ensures the smooth progress of the reaction. Furthermore, by controlling the mixing time of the first step at 70–75 hours, this invention promotes thorough stirring and ensures a homogeneous solution mixture.

[0057] In this invention, the mass ratio of the fluoride salt to graphite is preferably 10:1. In this invention, the graphite is preferably flake graphite.

[0058] In this invention, the solid content of the mixture obtained after mixing the fluoride salt, hydrogen fluoride solution and graphite is preferably 20-80%, and more preferably 30-70%.

[0059] In this invention, the etching and stripping temperature is 10–40°C, preferably 20–30°C, and more preferably 25°C; the etching and stripping time is 70–75 h, preferably 72 h. In this invention, the etching and stripping is preferably performed under stirring conditions. In this invention, the stirring speed is preferably 60–1350 rpm, and more preferably 70–1200 rpm. This invention ensures good graphene stripping effect by controlling the stirring speed.

[0060] The present invention controls the etching and stripping temperature at 10-40°C, which can avoid the large-scale evaporation of hydrogen fluoride and ensure the smooth progress of the reaction.

[0061] In this invention, the etching and stripping process is equivalent to chemically oxidizing and stripping graphite in a special non-aqueous hydrogen fluoride liquid system, using a second fluoride complex as an oxidant, under the synergistic effect of the first fluoride complex, to generate fluorinated graphene. Therefore, sufficient reaction time is required.

[0062] The principle of etching and stripping in this invention is as follows:

[0063] This invention utilizes fluoride complexes for redox reactions: the second fluoride complex acts as a strong oxidant, which can extract electrons from carbon atoms on the graphite surface; the first fluoride complex facilitates this electron transfer process.

[0064] Electrostatic repulsion drives exfoliation: When electrons are removed from the graphite surface, a charge of the same polarity accumulates on each graphene sheet. These charges generate electrostatic repulsion, creating gaps between the originally tightly stacked graphite layers; this increase in interlayer gaps provides the driving force for graphene exfoliation.

[0065] Manufacturing defect-free graphene: Compared with methods that directly use strong oxidants, this invention does not require the step of oxidizing graphite, which avoids various structural defects that may occur under strong oxidizing conditions, such as vacancies and dangling bonds, and the resulting graphene maintains a high degree of structural integrity.

[0066] Introducing controllable fluorine doping: During the exfoliation process, graphene combines with free fluorine ions to form fluorine-containing graphene.

[0067] The introduction of fluorine can endow graphene with new electronic structures and performance characteristics, providing possibilities for application expansion.

[0068] After the etching and stripping are completed, the present invention preferably cools the resulting mixed slurry, then adds a dispersant, and then sequentially centrifuges, washes, ultrasonically disperses and dries it to obtain the graphene.

[0069] In this invention, the cooling is preferably performed to 3-7°C.

[0070] In this invention, the dispersant preferably comprises N-methyl-2-pyrrolidone. In this invention, the mass ratio of the dispersant to the mixture obtained after mixing the fluoride salt, hydrogen fluoride solution, and graphite is preferably (10-20):1, more preferably (10-15):1, and even more preferably 10:1.

[0071] The dispersant functions as follows:

[0072] In this invention, the dispersant is capable of removing residual impurities. During the preparation of graphene, some unreacted first fluoride complexes and second fluoride complexes may remain. These impurities can be effectively removed by washing the graphene with a dispersant (such as N-methyl-2-pyrrolidone, NMP); in addition, the addition of NMP can also recover the fluoride salt solution.

[0073] Promoting graphene dispersion: Untreated graphene, due to its strong van der Waals forces, tends to aggregate and precipitate in non-aqueous liquids (i.e., the exfoliation and etching reaction system). Using dispersants such as NMP can help effectively disperse the exfoliated graphene in the solution, avoiding secondary aggregation.

[0074] Protecting the graphene structure: During centrifugation and washing, the dispersant can prevent the graphene sheets from being damaged under mechanical force, which helps to maintain the structural integrity of graphene and avoid defects.

[0075] Facilitates subsequent applications: Graphene dispersed in solvents such as NMP can be easily coated, sprayed, and processed for practical applications. Good dispersion is beneficial for leveraging the excellent properties of graphene.

[0076] In this invention, the centrifugation speed is preferably 3000–5000 rpm, more preferably 4000–4500 rpm; the centrifugation time is preferably 5 minutes. This invention ensures good graphene exfoliation effect by controlling the centrifugation speed.

[0077] This invention separates large particles by centrifugation, then washes them to remove residual reactants and byproducts while protecting the graphene structure; ultrasonic dispersion is used to ensure that the graphene sheets are fully dispersed in the solution, resulting in a uniform dispersion system.

[0078] This invention does not have special requirements for the ultrasonic dispersion process; it is sufficient to ensure that the resulting mixed slurry is dispersed evenly. This invention uses ultrasonic dispersion to ensure effective dispersion of graphene and avoid secondary aggregation.

[0079] The preparation method provided by this invention is simple, energy-efficient, and low-cost, and produces high-purity graphene. This invention does not require oxidation and reduction processes, reducing the introduction of impurities, and also eliminates the need for high-temperature calcination.

[0080] This invention uses hydrogen fluoride instead of concentrated sulfuric acid in the redox process, making the acidic waste liquid easy to recover; while concentrated sulfuric acid is corrosive and has strong oxidizing properties, resulting in high costs for subsequent waste liquid treatment and making it difficult to recover.

[0081] Figure 1 This is a flowchart illustrating the preparation of graphene according to the present invention. Figure 1 As shown, the present invention uses fluoride salts (i.e. Figure 1Potassium hexafluorosilicate and potassium hexafluoromanganate) and hydrogen fluoride solution (i.e. Figure 1 The first mixture of hydrogen fluoride and pyridine is carried out (i.e., Figure 1 Stirring at 25°C in water yields a stripping solution (i.e., ...). Figure 1 The mixture solution); then the stripping solution and graphite (i.e. Figure 1 The second mixing (i.e., flake graphite) is carried out. Figure 1 The mixture was stirred for 72 hours, then NMP was added, and the mixture was centrifuged, washed, and ultrasonically dispersed in sequence to obtain a graphene dispersion. The graphene was then obtained by vacuum freeze-drying.

[0082] To further illustrate the present invention, a method for preparing graphene provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0083] Example 1

[0084] The method for preparing graphene by exfoliating graphite with fluoride salts comprises the following steps:

[0085] 800g of potassium hexafluorosilicate solid powder and 200g of potassium hexafluoromanganate fluoride solid powder were mixed evenly and dissolved in 45000mL of hydrogen fluoride solution (the hydrogen fluoride-pyridine solution contained 70% by mass of hydrogen fluoride), and the mixture was stirred to obtain a mixed solution.

[0086] The mixed solution was transferred into a hydrothermal reactor and kept at 25°C for 72 hours to obtain a stripping solution.

[0087] 100g of flake graphite was added to the exfoliation solution, and the mixture was stirred at 25°C for 72 hours in a hydrothermal reactor, then cooled to 5°C. An appropriate amount of NMP was added to the cooled 5°C solution to prevent agglomeration, recover the fluoride salt solution, and protect the graphene. The resulting solution was centrifuged for 5 minutes to separate the graphene. The centrifuged graphene was washed with an appropriate solvent (such as pure water or ethanol) (washed twice with pure water, then once with ethanol), which can usually be repeated several times to ensure the removal of residual impurities. Centrifugation was performed again after each wash until the washing liquid became clear. The washed graphene dispersion was ultrasonically dispersed using an ultrasonic dispersion device to obtain a uniform graphene dispersion. The graphene dispersion was transferred to a vacuum drying oven and dried at 100°C for 24 hours to obtain graphene powder, i.e., the graphene.

[0088] Example 2

[0089] The method for preparing graphene by exfoliating graphite with fluoride salts comprises the following steps:

[0090] 800g of potassium hexafluorosilicate solid powder and 200g of potassium hexafluoromanganate solid powder were mixed evenly and dissolved in 45000mL of hydrogen fluoride-pyridine solution (in which the mass fraction of hydrogen fluoride in the hydrogen fluoride-pyridine solution was 70%) to obtain a mixed solution.

[0091] The mixed solution was transferred into a hydrothermal reactor and kept at 20°C for 70 hours to obtain a stripping solution.

[0092] 100g of flake graphite was added to the exfoliation solution, and the mixture was stirred at 20°C for 70 hours in a hydrothermal reactor, then cooled to 5°C. An appropriate amount of NMP was added to the cooled 5°C solution to prevent agglomeration, recover the fluoride salt solution, and protect the graphene. The resulting solution was centrifuged for 5 minutes to separate the graphene. The centrifuged graphene was washed with an appropriate solvent (such as pure water or ethanol) (washed twice with pure water, then once with ethanol), which can usually be repeated several times to ensure the removal of residual impurities. Centrifugation was performed again after each wash until the washing liquid became clear. The washed graphene dispersion was ultrasonically dispersed using an ultrasonic dispersion device to obtain a uniform graphene dispersion. The graphene dispersion was transferred to a vacuum drying oven and dried at 80°C for 12 hours to obtain graphene powder, i.e., the graphene.

[0093] Example 3

[0094] The method for preparing graphene by exfoliating graphite with fluoride salts comprises the following steps:

[0095] 800g of potassium hexafluorosilicate solid powder and 200g of potassium hexafluoromanganate solid powder were mixed evenly and dissolved in 45000mL of hydrogen fluoride solution (the hydrogen fluoride-pyridine solution contained 70% by mass of hydrogen fluoride) to obtain a mixed solution.

[0096] The mixed solution was transferred into a hydrothermal reactor and kept at 30°C for 75 hours to obtain a stripping solution.

[0097] 100g of flake graphite was added to the exfoliation solution, and the mixture was stirred at 30°C for 75 hours in a hydrothermal reactor, then cooled to 5°C. An appropriate amount of NMP was added to the cooled 5°C solution to prevent agglomeration, recover the fluoride solution, and protect the graphene. The resulting solution was centrifuged for 5 minutes to separate the graphene. The centrifuged graphene was washed with an appropriate solvent (such as pure water or ethanol) (washed twice with pure water, then once with ethanol), which can usually be repeated several times to ensure the removal of residual impurities. Centrifugation was performed again after each wash until the washing liquid became clear. The washed graphene dispersion was ultrasonically dispersed using an ultrasonic dispersion device to obtain a uniform graphene dispersion. The graphene dispersion was transferred to a vacuum drying oven and dried at 120°C for 24 hours to obtain graphene powder, i.e., the graphene.

[0098] Performance testing

[0099] Figure 2 The microstructure of the sample was observed using a scanning electron microscope, revealing a thin layer of material with obvious wrinkles.

[0100] Figure 3 Detailed analysis of the Raman spectrum: Peak D (Peak 1): typically appears at approximately 1350 cm⁻¹ -1 Nearby, associated with defects or edge conditions. G peak (Peak 2): typically appears at approximately 1580 cm. -1 Nearby, it correlates with the planar vibrational modes of graphene, indicating that sp 2 The presence of hybrid carbon atoms. 2D peak (Peak 3): typically appears at approximately 2700 cm⁻¹. -1 The peaks around 2900 cm⁻¹ are characteristic of the number and mass of graphene layers. The D+G peak (Peak 4) typically appears at approximately 2900 cm⁻¹. -1 Nearby is a combination peak of the D and G peaks.

[0101] Raman spectroscopy (with) Figure 3 The sample exhibits distinct Raman peaks at 1369.12 cm⁻¹, 1592.68 cm⁻¹, 2717.27 cm⁻¹, and 2934.41 cm⁻¹, which coincide with the D, G, 2D, and D+D' peaks of the Raman spectrum of carbon materials, respectively. In conclusion, this sample conforms to the basic characteristics of graphene.

[0102] Figure 3 In the diagram, the red curve represents the first Gaussian peak (Peak1(B)). This Gaussian peak is a Raman peak obtained by fitting a Gaussian function; the red curve corresponds to a displacement of 1373.59 cm. -1 The peaks on the left and right.

[0103] The green curve represents the second Gaussian peak (Peak2(B)). Also obtained through Gaussian function fitting, this Raman peak corresponds to a displacement of 1593.13 cm. -1 The peaks on the left and right.

[0104] The thick black line represents the actual Raman spectral data obtained from the experiment. As can be seen, the actual data (thick black line) matches the fitted curves (red and green) very well near the two main peaks.

[0105] also, Figure 3 The table provides detailed parameters for each peak, including peak center position (xc), full width at half maximum (FWHM), and peak height (Height).

[0106] Table 1. Element content of graphene obtained in Examples 1-3

[0107]

[0108] As shown in Table 1, the fluorine content in the graphene obtained by this invention is controlled at 1-20 atomic%, and the oxygen content is less than 5 atomic%. The fluorine to carbon atom ratio (F / C) is in the range of 0.01-0.3, indicating that the introduced fluorine atoms are controllable and will not be excessive.

[0109] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing graphene, characterized in that, Includes the following steps: Graphene is obtained by mixing fluoride salts, hydrogen fluoride solution and graphite, and then etching and exfoliating it. During the exfoliation process, graphene combines with free fluoride ions to form fluorine-containing graphene. The hydrogen fluoride solution contains 20-80% hydrogen fluoride by mass. The etching and stripping temperature is 10~40℃, and the time is 70~75h; The fluoride salts include potassium hexafluorosilicate and potassium hexafluoromanganate; The solvent in the hydrogen fluoride solution is one or more of N-methylpyrrolidone, methylamine, ethylamine, and pyridine.

2. The preparation method according to claim 1, characterized in that, The mass ratio of potassium hexafluorosilicate to potassium hexafluoromanganate is 4:

1.

3. The preparation method according to claim 1 or 2, characterized in that, The mass ratio of the fluoride salt to graphite is 10:

1.

4. The preparation method according to claim 1, characterized in that, The solid content of the mixture obtained by mixing the fluoride salt, hydrogen fluoride solution and graphite is 15-30%.

5. The preparation method according to claim 1, 2, or 4, characterized in that, The mass ratio of the fluoride salt to the volume ratio of the hydrogen fluoride solution is (12~120) g: 1 L.

6. The preparation method according to claim 1, 2 or 4, characterized in that, After the etching and stripping are completed, the resulting mixed slurry is cooled, then a dispersant is added, and then it is subjected to centrifugation, washing, ultrasonic dispersion and drying in sequence.

7. The preparation method according to claim 6, characterized in that, The cooling process involves cooling the temperature to 3-7°C.

8. The preparation method according to claim 6, characterized in that, The dispersant includes N-methyl-2-pyrrolidone.

9. The preparation method according to claim 8, characterized in that, The mass ratio of the dispersant to the mass of the mixture obtained after mixing the fluoride salt, hydrogen fluoride solution and graphite is (10~20):1.

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