Method for preparing fluorinated graphene based on SF6 in-situ hydrolysis method

Abstract

According to the method, graphene oxide serves as a raw material, SF6 gas serves as a fluorinating agent, SF6 is subjected to heat treatment in the presence of water vapor and then is subjected to in-situ hydrolysis to generate HF, controllable fluorine doping operation of graphene is achieved, due to introduction of fluorine atoms, the structure of fluorinated graphene is more stable, and the performance of fluorinated graphene is improved. Compared with the prior art, the fluorinated graphene prepared by the method can bear higher temperature without decomposition or performance degradation, the electronic structure of graphene is changed, graphene is endowed with higher chemical activity, and effective regulation and control of the band gap of the fluorinated graphene are realized at the same time. According to the method, the stable fluorinated graphene is generated by mildly controlling the reaction conditions, the use of highly toxic and highly corrosive reagents is avoided, meanwhile, the resource utilization of the waste greenhouse gas is realized, the equipment used in the preparation process is simple, and large-scale production is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon material development and relates to a method for preparing fluorinated graphene based on SF6 in-situ hydrolysis. Background Art

[0002] Graphene has been widely used in many fields such as catalyst carriers, energy storage materials, sensors and coatings due to its ultra-high specific surface area, excellent electrical conductivity, thermal conductivity and mechanical stability. However, graphene still faces inherent defects in practical applications. For example, its zero bandgap characteristics limit its application range in electronic devices, its chemical inertness leads to low adsorption capacity of reactants, and its insufficient thermal stability makes it difficult to maintain structural integrity under high temperature conditions. In response to these problems, researchers have chemically modified graphene by introducing heteroatoms (such as nitrogen, sulfur, fluorine, etc.), among which fluorination is considered to be an effective means to improve the performance of graphene. Fluorinated graphene has become a research hotspot in the field of materials because of its high-strength CF bond (bond energy of about 485 kJ / mol), high electronegativity and extremely strong chemical stability, which can significantly enhance the thermal stability of graphene, regulate the bandgap characteristics and improve the chemical activity.

[0003] Existing methods for preparing fluorinated graphene mostly rely on highly active fluorination agents (such as F2, XeF2, ClF3 or anhydrous HF), but these preparation processes have high safety risks, high costs and significant environmental hazards. For example, F2 and XeF2 are highly toxic gases with extremely strong corrosiveness and explosiveness. They need to be operated under special inert atmospheres and strict temperature control conditions, which limits their feasibility in industrial-scale production. Therefore, finding a green, safe and cost-controlled fluorination method to replace hazardous fluorination agents has become an important research direction in the preparation technology of fluorinated graphene. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for preparing fluorinated graphene based on SF6 in-situ hydrolysis, thereby solving the technical problems that the preparation of fluorinated graphene in the prior art relies on highly active fluorination reagents, has high safety risks and significant environmental hazards.

[0005] The present invention is achieved through the following technical solutions: A method for preparing fluorinated graphene comprises the following steps: S1: placing graphene oxide in a sealed container, and introducing nitrogen or an inert gas into the sealed container until the air in the reaction container is completely exhausted; S2: introducing SF6 gas containing H2O into a sealed container, and after the flow rate of the SF6 gas is stabilized, subjecting the reaction system to a programmed temperature treatment to allow SF6 to react with graphene oxide to obtain the fluorinated graphene.

[0006] Preferably, in step S1, the flow rate of the nitrogen or inert gas is 80-100 mL / min.

[0007] Preferably, in step S1, the nitrogen or inert gas is introduced for 5 to 10 minutes.

[0008] Preferably, the graphene oxide is multilayer graphene oxide.

[0009] Preferably, the flow rate of the SF6 gas is 100-200 mL / min.

[0010] Preferably, the volume percentage of H2O in the H2O-containing SF6 gas is 0.1% to 5%.

[0011] Preferably, the programmed temperature treatment is as follows: the temperature is increased to 600-620° C. at a heating rate of 5-10° C. / min, and the temperature is kept for reaction for 30-75 min.

[0012] Preferably, in step S2, after the reaction is completed, the system is further cooled until the temperature of the reaction system drops to room temperature to obtain the fluorinated graphene material; wherein the cooling rate is 5-10°C / min.

[0013] Preferably, while the system is being cooled, SF6 gas is continuously introduced into the system until the temperature of the reaction system drops to room temperature, thereby obtaining the fluorinated graphene material.

[0014] A fluorinated graphene is prepared by the above method; the fluorine content in the fluorinated graphene is 1% to 13%.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention provides a method for preparing fluorinated graphene, wherein the method uses graphene oxide as a raw material and SF6 gas as a fluorinating agent, and realizes controllable fluorine doping operation of graphene based on in-situ hydrolysis of SF6 after heat treatment in the presence of water vapor to generate HF. Due to the introduction of fluorine atoms, the structure of fluorinated graphene is more stable, and it can withstand higher temperatures without decomposition or performance degradation, which changes the electronic structure of graphene, gives graphene stronger chemical activity, and realizes effective regulation of the band gap of fluorinated graphene. The present invention generates stable fluorinated graphene by mildly controlling the reaction conditions, avoids the use of highly toxic and highly corrosive reagents, and realizes resource utilization of waste greenhouse gases. The equipment used in the preparation process is simple, which is conducive to large-scale production.

[0016] Furthermore, the flow rate of the nitrogen or inert gas is 80-100 mL / min, and the introduction time of the nitrogen or inert gas is 5-10 min. When the flow rate of the nitrogen or inert gas (such as argon, helium, etc.) is within this range, the air in the closed container (including oxygen, moisture, and other gases that may affect the reaction) can be effectively completely discharged, which ensures that the reaction is carried out in an oxygen-free, water-free and chemically stable environment, thereby avoiding unnecessary side reactions and the introduction of impurities; in addition, the appropriate nitrogen or inert gas flow rate and introduction time help to maintain a uniform distribution of gas concentration and temperature in the reaction system, thereby optimizing the reaction kinetic conditions, which helps to accelerate the hydrolysis of SF6 gas and its reaction with graphene oxide, and improve the yield and purity of fluorinated graphene.

[0017] Furthermore, the graphene oxide is multilayer graphene oxide, which has abundant oxygen-containing functional groups, such as hydroxyl, epoxy, carbonyl and carboxyl groups, which enhance its ability to interact with fluorine atoms, thereby generating fluorinated graphene with higher chemical activity; at the same time, the multilayer graphene oxide has obvious stratification, which is conducive to achieving uniform doping of fluorine atoms during the fluorination process and improving the quality of fluorinated graphene; after the multilayer graphene oxide is fluorinated, the introduction of fluorine atoms can stabilize the structure of graphene, so that it can withstand higher temperatures without decomposition or performance degradation.

[0018] Furthermore, the flow rate of the SF6 gas is 100-200 mL / min. The flow rate of the SF6 gas within this range can ensure that it fully contacts and reacts with graphene oxide. The appropriate flow rate helps to maintain the gas concentration in the reaction system, thereby optimizing the reaction rate and improving the yield and purity of fluorinated graphene. A stable SF6 gas flow rate helps to achieve uniform distribution of gas in the reaction system, thereby ensuring that the fluorination reaction on the surface of graphene oxide proceeds uniformly, which helps to reduce local over- or under-reaction and obtain a fluorinated graphene product with more consistent performance.

[0019] Furthermore, the volume percentage of H2O in the H2O-containing SF6 gas is 0.1%~5%. First, SF6 can undergo hydrolysis in the presence of water vapor to generate active species such as HF. These active species are crucial for the preparation of fluorinated graphene because they can react with the functional groups on the surface of graphene oxide to achieve the doping of fluorine atoms. Controlling the volume percentage of H2O within the range of 0.1%~5% can ensure that the hydrolysis reaction proceeds moderately, neither too violently causing the reaction to get out of control nor too slowly affecting the preparation efficiency. In addition, the presence of H2O can also promote the SF 6 In the fluorination reaction between graphene oxide and fluorinated graphene, an appropriate amount of water vapor helps to increase the activity of the reaction system and makes it easier for fluorine atoms to be doped into the structure of graphene. By precisely controlling the content of H2O, the fluorination effect can be optimized to obtain fluorinated graphene products with a specific fluorine content. Secondly, the performance of fluorinated graphene depends to a large extent on its degree of fluorination. By controlling the volume percentage of H2O, the degree of fluorination of fluorinated graphene can be adjusted to optimize its performance. For example, appropriate fluorination can improve the thermal stability, chemical activity and band gap regulation ability of graphene, making it have better performance in certain application fields.

[0020] Further, the programmed temperature treatment is specifically: the heating rate is 5~10℃ / min, the temperature is raised to 600~620℃, and the temperature is kept for 30~75 min. The programmed temperature treatment can ensure that the reaction system is gradually heated at an appropriate temperature, avoiding the influence of the rapid temperature change on the reaction. By controlling the heating rate at 5~10℃ / min, the molecules and atoms in the reaction system can have enough time to adapt and adjust, thereby promoting the reaction. Heating to the temperature range of 600~620℃ is a key temperature range in the preparation process of fluorinated graphene. Within this temperature range, the fluorination reaction between SF6 and gas and graphene oxide can be carried out efficiently to generate high-quality fluorinated graphene. The programmed temperature treatment helps to reduce the occurrence of side reactions. During the heating process, impurities and unreacted raw materials in the reaction system can be gradually eliminated or converted, thereby improving the purity of the product. The temperature is kept for 30~75 min to ensure that the reaction is fully carried out, so that fluorine atoms are fully doped into the structure of graphene, further improving the purity of the product. Through programmed temperature treatment, key performance indicators such as the fluorination degree, crystal structure and surface properties of fluorinated graphene can be controlled. The optimization of these properties is crucial for the application of fluorinated graphene in electronics, energy, biology and other fields.

[0021] Furthermore, in step S2, after the reaction is completed, the system is further subjected to a cooling treatment until the temperature of the reaction system drops to room temperature to obtain the fluorinated graphene material; wherein the cooling rate is 5 to 10°C / min, and the fluorinated graphene may undergo structural changes or decomposition at high temperatures, so the cooling treatment is an important step to protect its structural integrity. By controlling the cooling rate at 5 to 10°C / min, it can be ensured that the fluorinated graphene has enough time to adjust its structure during the cooling process to avoid structural damage caused by drastic temperature changes. Sharp temperature changes may cause thermal stress to be generated inside the reaction system, thereby causing cracking or deformation of the material. By gradually cooling, the generation of thermal stress can be reduced, and the integrity and performance of the fluorinated graphene material can be protected. The cooling treatment can also affect the crystal structure and surface properties of fluorinated graphene. An appropriate cooling rate helps to optimize these properties, so that it has better performance in certain application fields.

[0022] Furthermore, while the system is being cooled, SF6 gas is continuously introduced into the system until the temperature of the reaction system drops to room temperature to obtain the fluorinated graphene material. First, the continuous introduction of SF6 gas during the cooling process can ensure that the fluorinated graphene continues to react with SF6 during the cooling process, which helps to stabilize its structure, which can prevent the performance of the fluorinated graphene from degrading due to structural changes or decomposition during the cooling process. The continuous introduction of SF6 gas can ensure that the concentration of fluorine atoms in the reaction system remains at a relatively stable level, which helps to optimize the fluorination degree of the fluorinated graphene. The appropriate degree of fluorination is crucial to the performance of the fluorinated graphene and can affect its conductivity, thermal stability, chemical activity, etc.; in addition, the continuous introduction of SF6 gas can also reduce impurities and unreacted raw materials in the reaction system, thereby improving the purity of the product. During the cooling process, the unreacted SF6 gas can react with the impurities in the system to generate easily separable compounds, thereby purifying the reaction system; moreover, the rapid temperature change may cause thermal stress inside the fluorinated graphene, thereby affecting its performance. The continuous introduction of SF6 gas can slow down the cooling rate to a certain extent, thereby reducing the generation of thermal stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 The scanning electron microscope (SEM) image (a) and EDS spectrum (b) of the original graphene oxide in the present invention; Figure 2 The scanning electron microscope (SEM) image (a) and EDS spectrum (b) of the fluorinated graphene (product under low fluorination degree conditions) obtained in Example 1 of the present invention; Figure 3 The scanning electron microscope (SEM) image (a) and EDS spectrum (b) of the fluorinated graphene (product under medium fluorination conditions) obtained in Example 2 of the present invention; Figure 4 The following are the scanning electron microscope (SEM) image (a) and EDS spectrum (b) of the fluorinated graphene (product under high fluorination conditions) obtained in Example 3 of the present invention. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0026] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0027] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0028] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0029] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0030] The present invention provides a method for preparing fluorinated graphene, comprising the following steps: S1: Place 100-200 mg of graphene oxide with a purity greater than 99% in a sealed container, and introduce nitrogen or an inert gas at a flow rate of 80-100 mL / min for 5-10 min until the air in the reaction container is completely exhausted; wherein the inert gas includes one of helium or argon.

[0031] S2: SF6 gas containing 0.1% to 5% H2O by volume is introduced into the reaction container at a rate of 100 to 200 mL / min. After the flow rate of the gas flow is stable, the reaction system is subjected to a programmed temperature increase treatment to allow the SF6 gas to react with graphene oxide at a high temperature; the programmed temperature increase treatment is specifically as follows: a heating rate of 5 to 10°C / min, the temperature is increased to 600 to 620°C, and the reaction is kept at this temperature for 30 to 75 min.

[0032] S3: After the reaction of SF6 gas and graphene oxide is completed, the reaction system is cooled at a cooling rate of 5-10°C / min, and SF6 gas is continuously introduced into the reaction system until the temperature of the reaction system drops to room temperature, thereby obtaining the fluorinated graphene.

[0033] The present invention also discloses fluorinated graphene prepared by the above method, wherein the fluorine content in the fluorinated graphene is 1% to 13%.

[0034] The present invention overcomes the technical difficulties of using highly toxic and highly corrosive fluorinating agents in the process of preparing fluorinated graphene in the prior art, and achieves better performance in application. The present invention proposes a safe method for preparing fluorinated graphene based on in-situ hydrolysis of SF6, realizing a green, economical and efficient preparation process. The core is to develop an environmentally friendly fluorinated graphene preparation strategy using the weak interaction of SF6 (aqueous solution cracking). SF6 is hydrolyzed in situ under mild conditions to generate active HF fluorinated molecules without the need for additional hazardous gas treatment equipment; the degree of fluorination (i.e., CF ratio) can be precisely controlled by adjusting the reaction conditions (such as temperature and pressure).

[0035] The fluorination reaction principle of this process is: SF6 hydrolyzes into active fluoride ions: SF6+H2O→HF+SO x HF acts as a fluorinating agent to chemically bond with graphene to generate fluorinated graphene (FG): C-H+HF→C-F+H2 The preparation method of fluorinated graphene material in the present invention allows graphene oxide and SF6 gas to directly undergo deoxygenation fluorination reaction at high temperature, specifically, fluorinated graphene reacts with SF6 gas, fluorine element is doped into graphene oxide, and at the same time, at a reaction temperature of 600~620℃, a fluorinated graphene material with a relatively high fluorine content is directly obtained, and the overall reaction is mild and safe, without the need to introduce pure F2, avoiding the risk of high-energy explosion or high corrosion. In addition, the reaction is protected by nitrogen or inert gas in the early stage of the reaction, which effectively avoids the occurrence of side reactions, ensures the purity of the product, and makes the reaction system safer. Compared with the existing preparation method of fluorinated graphene material, this method has simple equipment, convenient operation, and safe synthesis process, and is suitable for large-scale preparation of fluorinated graphene materials in laboratories.

[0036] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0037] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0038] Example 1 A method for preparing fluorinated graphene comprises the following steps: weighing 100 mg of graphene oxide into a quartz crucible, continuously passing nitrogen into a tubular furnace at a gas flow rate of 80 mL / min until the air in the tubular furnace is emptied, and then slowly passing SF6 gas containing 0.1% H2O into the tubular furnace at a flow rate of 100 mL / min, and after the gas flow is stable, heating the temperature to 600°C at a rate of 10°C / min, and keeping the temperature for 30 min, so that high-purity graphene oxide and SF6 fully undergo thermal decomposition reaction. After the reaction is completed, continue to pass SF6 gas, wait until the temperature drops to room temperature, collect the black fluorinated graphene solid product, and the F element content in the characterization analysis is 1.91%.

[0039] Example 2 A method for preparing fluorinated graphene comprises the following steps: weighing 100 mg of graphene oxide into a quartz crucible, continuously passing nitrogen into a tubular furnace at a gas flow rate of 80 mL / min until the air in the tubular furnace is emptied, and then slowly passing SF6 gas containing 3% H2O into the tubular furnace at a flow rate of 100 mL / min, and after the gas flow is stable, heating the temperature to 600°C at a rate of 10°C / min, and keeping the temperature for 60 min, so that high-purity graphene oxide and SF6 gas fully undergo thermal decomposition reaction. After the reaction is completed, continue to pass SF6 gas, wait until the temperature drops to room temperature, collect the black fluorinated graphene solid product, and the F element content in the characterization analysis is 7.18%.

[0040] Example 3 A method for preparing fluorinated graphene comprises the following steps: weighing 100 mg of graphene oxide into a quartz crucible, continuously passing nitrogen gas into a tubular furnace at a gas flow rate of 80 mL / min until the air in the tubular furnace is emptied, and then slowly passing SF6 gas containing 5% H2O into the tubular furnace at a flow rate of 100 mL / min, and after the gas flow is stable, heating the temperature to 600°C at a rate of 10°C / min, and keeping the temperature for 75 min, so that high-purity graphene oxide and SF6 fully undergo thermal decomposition reaction. After the reaction is completed, continue to pass SF6 gas, wait until the temperature drops to room temperature, collect the black fluorinated graphene solid product, and the F element content in the characterization analysis is 12.83%.

[0041] Example 4 A method for preparing fluorinated graphene comprises the following steps: S1: Place 100 mg of graphene oxide with a purity greater than 99% in a sealed container and introduce nitrogen at a flow rate of 80 mL / min for 5 min until the air in the reaction container is completely exhausted; S2: SF6 gas containing 0.1% H2O by volume is introduced into the reaction container at a rate of 100 mL / min. After the flow rate of the gas flow is stable, the reaction system is subjected to a programmed temperature treatment to allow the SF6 gas and graphene oxide to react at a high temperature; the programmed temperature treatment is specifically as follows: the heating rate is 5°C / min, the temperature is raised to 600°C, and the reaction is kept at this temperature for 75 min.

[0042] S3: After the reaction of SF6 gas and graphene oxide is completed, the reaction system is cooled at a cooling rate of 5°C / min, and SF6 gas is continuously introduced into the reaction system until the temperature of the reaction system drops to room temperature, thereby obtaining the fluorinated graphene.

[0043] Example 5 A method for preparing fluorinated graphene comprises the following steps: S1: Place 200 mg of graphene oxide with a purity greater than 99% in a sealed container and introduce helium at a flow rate of 100 mL / min for 10 min until the air in the reaction container is completely exhausted; S2: SF6 gas containing 5% H2O by volume is introduced into the reaction container at a rate of 200 mL / min. After the flow rate of the gas flow is stable, the reaction system is subjected to a programmed temperature increase treatment to allow the SF6 gas and graphene oxide to react at a high temperature; the programmed temperature increase treatment is specifically as follows: the heating rate is 10°C / min, the temperature is increased to 620°C, and the reaction is kept at this temperature for 30 minutes.

[0044] S3: After the reaction of SF6 gas and graphene oxide is completed, the reaction system is cooled at a cooling rate of 10°C / min, and SF6 gas is continuously introduced into the reaction system until the temperature of the reaction system drops to room temperature, thereby obtaining the fluorinated graphene.

[0045] Example 6 A method for preparing fluorinated graphene comprises the following steps: S1: Place 150 mg of graphene oxide with a purity greater than 99% in a sealed container and introduce argon gas at a flow rate of 90 mL / min for 5-10 min until the air in the reaction container is completely exhausted; S2: SF6 gas containing 2% H2O by volume is introduced into the reaction container at a rate of 150 mL / min. After the flow rate of the gas flow is stable, the reaction system is subjected to a programmed temperature increase treatment to allow the SF6 gas and graphene oxide to react at a high temperature; the programmed temperature increase treatment is specifically as follows: the heating rate is 8°C / min, the temperature is increased to 610°C, and the reaction is kept at this temperature for 50 min.

[0046] S3: After the reaction of SF6 gas and graphene oxide is completed, the reaction system is cooled at a cooling rate of 8°C / min, and SF6 gas is continuously introduced into the reaction system until the temperature of the reaction system drops to room temperature, thereby obtaining the fluorinated graphene.

[0047] Figure 1 is a scanning electron microscope (SEM) image and EDS spectrum diagram of the original graphene oxide in the present invention, Figure 1 From the SEM, it can be seen that the original graphene oxide has a typical two-dimensional wrinkled structure, and its sheet orientation and layered stacking give it a high theoretical specific surface area. However, the unchemically modified graphene oxide shows obvious chemical inertness and lacks active sites on the surface, which is not conducive to further functionalization and synergistic effects with reactants. Figure 1From the EDS spectrum, it can be seen that the elemental composition is mainly carbon (C) and a small amount of oxygen (O), of which the atomic percentage of carbon is 97.4% and the oxygen content is less than 3%. No fluorine signal was found, proving that the original sample does not contain fluorine. This shows that the unmodified graphene oxide lacks chemically active sites that can be regulated, further highlighting the necessity of improving the reactivity and functionality of graphene through fluorination modification. The SF6 in-situ safe fluorination strategy proposed in the present invention can efficiently give graphene oxide higher chemical activity while maintaining the integrity of its layered structure.

[0048] Figure 2 The SEM image and EDS spectrum of the fluorinated graphene material prepared in Example 1 of the present invention are shown in FIG. Figure 2 From the SEM, it can be seen that after fluorination, the sample basically retains the original graphene two-dimensional sheet structure, and the surface wrinkles still exist, but the edges of the particles are slightly expanded, indicating that the fluorination modification has moderately modified the surface under low concentration conditions, and at the same time has not caused obvious damage to the graphene two-dimensional sheet. The enhancement of the surface layering further proves that the surface chemical active sites are introduced during the fluorination process, which reflects the mild reaction and good control effect. Figure 2 From the EDS spectrum, it can be seen that 2.95% of fluorine (F) elements were introduced into the sample, while the carbon content was slightly reduced to 93.45%, and the oxygen content did not change significantly. This shows that the fluoride generated by in-situ hydrolysis of SF6 under the conditions of the present invention successfully achieved surface modification and formed a stable CF bond. The experimental results show that the low-fluorination product retains the high conductivity of graphene while adding an appropriate amount of controllable chemical active sites, which is suitable for use as a catalyst support material, especially for catalytic applications that require high conductivity and reaction flexibility.

[0049] Figure 3 The SEM image and EDS spectrum of the fluorinated graphene material prepared in Example 2 of the present invention are shown in FIG. Figure 3 From the SEM, we can see that the graphene particles are more closely aggregated, and the edges of the surface particles show a certain degree of smoothness at high resolution. This shows that with the increase of the degree of fluorination, the chemical modification range of the sample is expanded, the proportion of surface-bonded CF bonds increases, and its chemical reactivity is enhanced. However, it is worth noting that the layered lamellae structure of graphene is not destroyed, indicating that the reaction is still mild and controlled. Figure 3 From the EDS spectrum, we can see that the atomic percentage of fluorine element has increased significantly to 7.22%, while the carbon content has dropped to 88.62%. The oxygen content has further decreased, suggesting that some surface hydroxyl groups and carbon-oxygen bonds have been successfully replaced by CF bonds. Under moderate fluorination conditions, the proportion of CF bonds on the graphene surface has increased, giving the material higher thermal stability and surface activity, while introducing obvious hydrophobic properties.

[0050] Figure 4 The SEM image and EDS spectrum of the fluorinated graphene material prepared in Example 3 of the present invention are shown in FIG. Figure 4 From the SEM, we can see that as the concentration of the fluorinating agent increases, the two-dimensional wrinkle morphology of graphene changes significantly, the edges between particles tend to be rounded, and the overall surface becomes smoother. High-resolution SEM shows that the surface is covered with more complete CF bonds, and the interlayer roughness is reduced. This morphological change indicates that the fluorination reaction is more complete under this condition, and the surface is basically covered by high-concentration CF bond chemical modification. Figure 4 From the EDS spectrum, we can see that the atomic percentage of fluorine element increases to 13.81%, while the carbon content further decreases to 83.96%. This result clearly proves that high concentration conditions significantly increase the formation ratio of surface CF bonds and enhance the chemical stability of the material. Graphene with a high degree of fluorination exhibits extremely high chemical corrosion resistance and hydrophobicity, making it an ideal choice for anti-corrosion coating materials. At the same time, this structure, combined with high thermal stability, has important application potential in electronic device materials.

[0051] from Figure 2~Figure 4 The experimental results show that by adjusting the reaction conditions and concentration of SF6, the present invention achieves controllable preparation of graphene samples from low fluorination to high fluorination. The SEM images show the gradual evolution of the material morphology, and the EDS spectrum shows the precise control of the CF bond introduction efficiency and fluorine content during the fluorination process.

[0052] Materials with different fluorine contents can be applied in different scenarios. Low fluorination is suitable for catalyst materials and retains high conductivity; medium fluorination is suitable for energy storage devices, taking into account both activity and stability; high fluorination has unique advantages in the field of anti-corrosion coatings.

[0053] The fluorination reaction of the present invention adopts the SF6 in-situ hydrolysis method, without the use of highly toxic or highly corrosive fluorination reagents (such as F2, HF, etc.), effectively avoiding the safety hazards and environmental risks of traditional processes. The green and efficient SF6 fluorinated graphene preparation system of the present invention can be widely adapted to various application scenarios, reflecting the innovation and scientific value in the field of material chemistry design and sustainable preparation.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing fluorinated graphene, characterized in that: The following steps are involved: S1: placing graphene oxide in a sealed container, and introducing nitrogen or an inert gas into the sealed container until the air in the reaction container is completely exhausted; S2: introducing SF6 gas containing H2O into a sealed container, and after the flow rate of the SF6 gas is stabilized, subjecting the reaction system to a programmed temperature treatment to allow SF6 to react with graphene oxide to obtain the fluorinated graphene.

2. The method for preparing fluorinated graphene according to claim 1, characterized in that: In step S1, the flow rate of the nitrogen or inert gas is 80-100 mL / min.

3. The method for preparing fluorinated graphene according to claim 1, characterized in that: In step S1, the nitrogen or inert gas is introduced for 5 to 10 minutes.

4. The method for preparing fluorinated graphene according to claim 1, characterized in that: The graphene oxide is multi-layer graphene oxide.

5. The method for preparing fluorinated graphene according to claim 1, characterized in that: The flow rate of the SF6 gas is 100-200 mL / min.

6. The method for preparing fluorinated graphene according to claim 1, characterized in that: The volume percentage of H2O in SF6 gas containing H2O is 0.1%~5%.

7. The method for preparing fluorinated graphene according to claim 1, characterized in that: The programmed temperature treatment is specifically as follows: the temperature is increased to 600-620° C. at a heating rate of 5-10° C. / min, and the temperature is kept for reaction for 30-75 min.

8. The method for preparing fluorinated graphene according to claim 1, characterized in that: In step S2, after the reaction is completed, the system is cooled until the temperature of the reaction system drops to room temperature to obtain the fluorinated graphene material; wherein the cooling rate is 5-10°C / min.

9. The method for preparing fluorinated graphene according to claim 8, characterized in that: While the system is being cooled, SF6 gas is continuously introduced into the system until the temperature of the reaction system drops to room temperature, thereby obtaining the fluorinated graphene material.

10. A fluorinated graphene, characterized in that: The method according to any one of claims 1 to 9 is used to prepare the fluorinated graphene; the fluorine content in the fluorinated graphene is 1% to 13%.

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