CN117383549A - Method for preparing low-defect nanoscale graphene by physical method - Google Patents
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Classifications
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- 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
- C01B32/184—Preparation
- C01B32/19—Preparation by exfoliation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
Abstract
The invention discloses a method for preparing low-defect nanoscale graphene by a physical method. In the process of preparing graphene, csOH is firstly used for preprocessing natural graphite to enable a small amount of polar functional groups to be attached to the surface of the natural graphite, so that the dimethyl formamide is beneficial to being taken as a supercritical molecule to enter a graphite interlayer for stripping by utilizing a bipolar effect, and meanwhile, the CsOH is beneficial to increasing the interlayer spacing of the graphite powder during the preprocessing of the graphite powder. At the same time use Na 2 SO 3 Carrying out high-temperature ultrasonic treatment reduction treatment on the obtained graphene, and simultaneously forming SO (sulfur oxide) at the reduction degree of the graphene 4 2‑ The graphene rich in electrons has an electrostatic repulsion effect, and is favorable for further stripping of graphite. The three materials play a synergistic role, so that the stripping efficiency of graphite is improved, and the low-defect nanoscale graphene is obtained.
Description
Technical Field
The invention belongs to the field of graphene preparation, and particularly relates to a method for preparing low-defect nanoscale graphene by a physical method.
Background
Graphene has been increasingly focused on its excellent physical and chemical propertiesHigh yield of graphene is critical for future development and application of graphene 2 A hexagonal two-dimensional nanomaterial with honeycomb lattice and composed of hybridized orbitals. The graphene has excellent optical, electrical and mechanical properties, has important application prospects in the aspects of material science, textile industry, energy sources, medical treatment, drug delivery and the like, and is considered as a novel black gold material in the future. Currently, the usual methods for producing graphene are a mechanical exfoliation method, a redox method, a chemical vapor deposition method, a liquid phase exfoliation method, and a silicon carbide epitaxial growth method. Each method has respective advantages and disadvantages. The mechanical stripping method is to obtain the graphene thin layer material by utilizing friction and relative motion between an object and graphite. The method is simple to operate, and the obtained graphene generally maintains a complete crystal structure and has high quality, but the method has low production efficiency and low controllability. Graphene prepared by adopting the redox method contains rich oxygen-containing functional groups, is easy to modify, is expected to realize large-scale production, but the prepared graphene has a lot of defects, and the strong acid used has high risk and serious environmental pollution. Silicon carbide epitaxial growth method makes silicon atom sublimate rapidly and separate from material through vacuum high temperature environment, and the rest carbon atoms are recombined, so that graphene based on SiC substrate is obtained. The method can obtain high-quality graphene, but has high equipment requirements, and mass production is difficult to realize. The chemical vapor deposition method is a method for obtaining a graphene film material by vapor deposition by taking carbon-containing organic gas as a raw material, and is the most effective method for producing a graphene film at present. The graphene prepared by the method has the characteristics of large area and high quality, but the equipment cost is higher at the present stage, the experimental conditions are harsh, and the process conditions are further improved. Therefore, how to efficiently and quantitatively produce graphene is a great difficulty in China and even the world.
Based on the problems in the background art, the invention aims to provide a low-defect nanoscale graphene method prepared by a physical method. In the process of preparing graphene, csOH is used for preprocessing natural graphite to enable a small amount of polar functional groups to be attached to the surface of the natural graphite, dimethylformamide is a typical polar solvent, and the natural graphite is prepared through double processesThe polar interaction, the solvent molecule can adsorb to the natural graphite surface after CsOH pretreatment, and a large number of supercritical solvent molecules are stacked to the interlayer entrance of the graphite, so that the intercalation and stripping processes are promoted. On the other hand, pretreatment of CsOH can increase the interlayer spacing of graphite to some extent, thereby improving the exfoliation efficiency. The natural graphite pretreated by CsOH is selected as an initial raw material for supercritical fluid stripping, so that the method is a potential method for preparing high-quality graphene in a large scale, and the pretreatment of CsOH and dimethylformamide molecules in a supercritical state play a synergistic effect, so that the stripping efficiency of the graphene is improved. At the same time, na is used 2 SO 3 Carrying out high-temperature ultrasonic treatment on the obtained graphene SO 3 2- The partially oxidized graphene is reduced between the infiltration layers, SO that the reduction degree of the graphene is ensured, and simultaneously SO is formed 4 2- The graphene rich in electrons has an electrostatic repulsion effect, and is favorable for further stripping of graphite. The three materials play a synergistic role, so that the stripping efficiency of graphite is improved, and the low-defect nanoscale graphene is obtained.
Disclosure of Invention
In order to solve the defects in the prior art, in the process of preparing graphene, csOH is used for preprocessing natural graphite to enable a small amount of polar functional groups to be attached to the surface of the natural graphite, dimethylformamide is a typical polar solvent, solvent molecules can be adsorbed to the surface of the CsOH preprocessed natural graphite through bipolar interaction, and a large amount of supercritical solvent molecules are stacked to an interlayer inlet of the graphite, so that intercalation and stripping processes are promoted. On the other hand, pretreatment of CsOH can increase the interlayer spacing of graphite to some extent, thereby improving the exfoliation efficiency. The natural graphite pretreated by CsOH is selected as an initial raw material for supercritical fluid stripping, so that the method is a potential method for preparing high-quality graphene in a large scale, and the pretreatment of CsOH and dimethylformamide molecules in a supercritical state play a synergistic effect, so that the stripping efficiency of the graphene is improved. At the same time, na is used 2 SO 3 Carrying out high-temperature ultrasonic treatment on the obtained graphene SO 3 2- Infiltration layers for partially oxidized grapheneReducing, ensuring the reduction degree of graphene and simultaneously forming SO 4 2- The graphene rich in electrons has an electrostatic repulsion effect, and is favorable for further stripping of graphite. The three materials play a synergistic role, so that the stripping efficiency of graphite is improved, and the low-defect nanoscale graphene is obtained.
In order to achieve the above purpose, the invention provides a method for preparing low-defect nanoscale graphene by a physical method, which comprises the following specific preparation steps:
s1, adding 10-30ml of solution with the concentration of 0.01-0.05mol/LCsOH into a beaker filled with 0.5-3.5g of natural graphite powder, continuously stirring by a magnetic stirrer at room temperature for 10-50 minutes, finally separating solids by a glass filter, washing by using deionized water in a repeated manner, and drying in a blast drying box to thoroughly remove water and residual CsOH on the surface of graphite.
S2, adding the natural graphite powder obtained in the step S1 into a test tube, adding a corresponding volume of dimethylformamide solution into the test tube, fully mixing the natural graphite powder with the dimethylformamide solvent for 5-30 minutes by using a low-energy ultrasonic cleaner, carefully transferring the mixture into a stainless steel reactor by using a dropper, heating the sealed reactor in a quartz tube furnace at a heating rate of 2-10 ℃/min, ensuring that the actual temperature of the mixture in the reactor reaches the preset temperature of 350-450 ℃, and then keeping the temperature for 5-20 minutes after the actual temperature in the reactor reaches the preset temperature;
s3, after the natural graphite is successfully stripped, rapidly cooling the hot reactor in an ice-cold ice-water mixture tank, slowly opening the reactor after the reactor is completely cooled, pouring the product into a test tube, precipitating for a while, performing solid-liquid separation by using a glass suction filter, and cleaning the filter membrane which is an organic polytetrafluoroethylene membrane with deionized water for a plurality of times in the suction filtration process so as to completely clean the residual dimethylformamide;
s4, adding the graphite powder treated by the S3 into a powder containing 10-30ml of Na 2 SO 3 Heating and ultrasonic treating the solution in glass bottle with ultrasonic parameters set at 30-60kHz and 50-80deg.C, and finally adding the productAnd (5) placing the washed product into a vacuum drying oven for drying treatment after washing for a plurality of times. Due to SO 3 2- The partially oxidized graphene is reduced between the infiltration layers, SO that the reduction degree of the graphene is ensured, and simultaneously SO is formed 4 2- The graphene with rich electrons has the effect of electrostatic repulsion, so that the quality of the graphene is improved while the high stripping efficiency is ensured.
Preferably, the ultrasonic treatment time in the step S4 is 20 minutes.
Preferably, the temperature of the oven in the step S4 is 60 ℃, and the drying time is 12 hours.
The invention has the technical effects and advantages that:
1. the CsOH is used for preprocessing natural graphite, so that a small amount of polar functional groups are attached to the surface of the natural graphite, dimethylformamide is a typical polar solvent, solvent molecules can be adsorbed to the surface of the CsOH preprocessed natural graphite through bipolar interaction, and a large amount of supercritical solvent molecules are stacked to an interlayer inlet of the graphite, so that intercalation and stripping processes are promoted.
2. Pretreatment of CsOH can increase the interlayer spacing of graphite to some extent, thereby improving exfoliation efficiency. The natural graphite pretreated by CsOH is selected as an initial raw material for supercritical fluid stripping, so that the method is a potential method for preparing high-quality graphene in a large scale, and the pretreatment of CsOH and dimethylformamide molecules in a supercritical state play a synergistic effect, so that the stripping efficiency of the graphene is improved.
3. Using Na 2 SO 3 Carrying out high-temperature ultrasonic treatment on the obtained graphene SO 3 2- The partially oxidized graphene is reduced between the infiltration layers, SO that the reduction degree of the graphene is ensured, and simultaneously SO is formed 4 2- The graphene rich in electrons has an electrostatic repulsion effect, and is favorable for further stripping of graphite. The three materials play a synergistic role, so that the stripping efficiency of graphite is improved, and the low-defect nanoscale graphene is obtained.
Drawings
FIG. 1 is an XRD pattern of a graphite deposit of the natural graphite of example 1 and comparative examples 1-3 of the present invention, which was subjected to step S1.
Fig. 2 is a graph of the yields of graphene of example 2 and comparative examples 1 and 4-7.
Fig. 3 is a raman diagram of graphene prepared in example 3 and comparative example 8 of the present invention.
Fig. 4 is an electronic scan of graphene prepared in example 3 of the present invention.
Fig. 5 is an electronic scan of graphene prepared according to comparative example 8 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
S1, adding 10ml of solution with the concentration of 0.01mol/L CsOH into a beaker filled with 0.5g of natural graphite powder, continuously stirring by a magnetic stirrer at room temperature for 10 minutes, finally separating solids by a glass filter, washing by reuse deionized water, and drying in a forced air drying box to thoroughly remove water and residual CsOH on the surface of graphite.
S2, adding the natural graphite powder treated in the step S1 into a test tube, adding 4ml of dimethylformamide solution into the test tube, fully mixing the natural graphite powder with the dimethylformamide solvent for 30 minutes by using a low-energy ultrasonic cleaner, carefully transferring the mixture into a stainless steel reactor by using a dropper, heating the closed reactor in a quartz tube furnace at a heating rate of 5 ℃/min, ensuring that the actual temperature of the mixture in the reactor reaches a preset temperature of 350 ℃, and then keeping the temperature for 5 minutes after the actual temperature in the reactor reaches the preset temperature;
s3, after the natural graphite is successfully stripped, rapidly cooling the hot reactor in an ice-cold ice-water mixture tank, slowly opening the reactor after the reactor is completely cooled, pouring the product into a test tube, precipitating for a while, performing solid-liquid separation by using a glass suction filter, and cleaning the filter membrane which is an organic polytetrafluoroethylene membrane with deionized water for a plurality of times in the suction filtration process so as to completely clean the residual dimethylformamide;
s4, adding the graphite powder treated by the S3 into a graphite powder filled with 10ml of Na 2 SO 3 And (3) carrying out heating ultrasonic treatment in a glass bottle of the solution, setting ultrasonic parameters to be 30kHz, setting the temperature to be 50 ℃, lasting for 20 minutes, and finally, washing the product for multiple times and then putting the product into a vacuum drying oven for drying treatment.
Comparative example 1
The procedure of example 1 was repeated except that CsOH was not added in step S1.
Comparative example 2
In step S1, the procedure was the same as in example 1, except that CsOH was replaced with NaOH.
Comparative example 3
In step S1, the procedure was the same as in example 1, except that CsOH was replaced with KOH.
FIG. 1 shows XRD patterns of graphite deposits of the natural graphite treated in step S1 in example 1 and comparative examples 1 to 3 of the present invention, in which the (002) diffraction peak positions of comparative examples 1 to 2 are substantially identical to those of the natural graphite, and the diffraction peak positions of comparative example 3 are slightly smaller, and the deviation of example 1 is more remarkable. The Bragg formula shows that the interlayer spacing of the natural graphite in the example 1 is gradually increased after CsOH treatment and is obviously larger than that of the products in the comparative examples 1-3, the intercalated position provides a path for intercalation of dimethylformamide solvent molecules, and the interlayer spacing change effect is superior to that of NaOH and KOH, and is suspected to be caused by the difference of cation radius. Meanwhile, the diffraction peak intensities of comparative examples 1-3 and example 1 are about the same, which indicates that the original characteristic structure of the graphene precipitate obtained in the pretreatment process is not destroyed and remains intact.
Example 2
S1, adding 20ml of solution with the concentration of 0.02mol/L CsOH into a beaker filled with 1.5g of natural graphite powder, continuously stirring by a magnetic stirrer at room temperature for 20 minutes, finally separating solids by using a glass filter, washing by using de-ionized water in a repeated manner, and drying in a forced air drying box to thoroughly remove the moisture and residual CsOH on the surface of the graphite.
S2, adding the natural graphite powder treated in the step S1 into a test tube, adding 6ml of dimethylformamide solution into the test tube, fully mixing the natural graphite powder with the dimethylformamide solvent for 15 minutes by using a low-energy ultrasonic cleaner, carefully transferring the mixture into a stainless steel reactor by using a dropper, heating the closed reactor in a quartz tube furnace at a heating rate of 8 ℃/min, ensuring that the actual temperature of the mixture in the reactor reaches a preset temperature of 380 ℃, and then keeping the temperature for 15 minutes after the actual temperature of the mixture in the reactor reaches the preset temperature;
s3, after the natural graphite is successfully stripped, rapidly cooling the hot reactor in an ice-cold ice-water mixture tank, slowly opening the reactor after the reactor is completely cooled, pouring the product into a test tube, precipitating for a while, performing solid-liquid separation by using a glass suction filter, and cleaning the filter membrane which is an organic polytetrafluoroethylene membrane with deionized water for a plurality of times in the suction filtration process so as to completely clean the residual dimethylformamide;
s4, adding the graphite powder treated by the S3 into a graphite powder filled with 20ml of Na 2 SO 3 And (3) carrying out heating ultrasonic treatment in a glass bottle of the solution, setting ultrasonic parameters to be 40kHz, setting the temperature to be 60 ℃, lasting for 20 minutes, and finally, washing the product for multiple times and then putting the product into a vacuum drying oven for drying treatment.
Comparative example 4
In step S2, the procedure of example 2 was repeated except that dimethylformamide was not added.
Comparative example 5
In step S2, the procedure of example 2 was repeated except that dimethylformamide was replaced with N-methylpyrrolidone.
Comparative example 6
The procedure of example 2 was repeated except that dimethylformamide was replaced with gamma-butyrolactone in step S2.
Comparative example 7
The procedure of example 2 was repeated except that dimethylformamide was replaced with 1-vinyl-2-pyrrolidone in step S2.
To test the yields of graphene of example 2 and comparative examples 1 and 4-7, measurements were made using a visible light spectrophotometer. The solid products obtained in comparative examples 4 to 6 were first poured into a test tube, 10ml of fresh dimethylformamide solvent was added, followed by ultrasonic dispersion using an ultrasonic cleaner, and left to stand for 12 hours, causing large particles to precipitate, and the dispersion had a remarkable delamination phenomenon, namely, supernatant and precipitate without peeling. Graphene is present in the supernatant but some relatively thick graphite flakes may be present, and in order to separate them, centrifugation is typically used at a speed of 3000r/min for 5 minutes. Thus, only graphene exists in the supernatant finally, and the accuracy of the yield is ensured. The solid product obtained in example 2 was selected as a standard sample, which was used as a reference sample for measurement by a visible light spectrophotometer, while the concentration of the standard sample was known. It was poured into a test tube, 10ml of fresh dimethylformamide solvent was added, followed by ultrasonic dispersion using an ultrasonic cleaner. After 12 hours of standing, large particles are precipitated, obvious layering phenomenon is generated in the dispersion liquid, and supernatant liquid and precipitation without stripping are generated. Centrifugal separation was carried out at a speed of 3000r/min for 5 minutes. This ensures that only graphene is dispersed in the supernatant. And filtering and separating the dispersion liquid by using a polytetrafluoroethylene membrane, drying the obtained solid in a blast drying box, weighing the total mass of the solid and the filter membrane, and subtracting the mass of the filter membrane from the total mass to obtain the mass of the graphene. To reduce experimental error, the experiment was repeated 3 times and the average was taken. The mass ratio of the graphene product to the raw material mass (20 mg) gave a yield of 4.57% of the standard sample calculated. The solid product obtained in example 2 was used as a reference sample, and the graphene concentration in the solid products obtained in comparative examples 4 to 6 was obtained by using a visible spectrophotometer, and the quality and yield of graphene were calculated. This yield measurement method causes errors in yield due to a small amount of product remaining in the reactor, but produces a constant systematic error for all yields.
Fig. 2 is a graph of the yields of graphene of example 2 and comparative examples 1 and 4-7 (see table 1 for specific data). The yields of graphene were measured at 7 different wavelengths using a visible spectrophotometer and finally averaged to give the yields of graphene of example 2 and comparative examples 1 and 4-7 of 4.57%, 0.82%, 0.48%, 1.38%, 1.73% and 1.83%, respectively. From this, it can be seen that the graphene yield of comparative examples 1 and 4 is far lower than that of example 2, a small amount of polar functional groups are attached to the surface of the CsOH-treated natural graphene, dimethylformamide is a typical polar solvent, solvent molecules can be adsorbed to the surface of the CsOH-pretreated natural graphite through bipolar interaction, and a large amount of supercritical solvent molecules are stacked to the interlayer entrance of the graphite, so that intercalation and exfoliation processes are promoted; pretreatment of CsOH can increase the interlayer spacing of graphite to some extent, thereby improving exfoliation efficiency. The natural graphite pretreated by CsOH is selected as an initial raw material for supercritical fluid stripping, so that the method is a potential method for preparing high-quality graphene in a large scale, and the pretreatment of CsOH and dimethylformamide molecules in a supercritical state play a synergistic effect, so that the stripping efficiency of the graphene is improved. And the pretreatment of CsOH and the dimethylformamide molecules in the supercritical state play a synergistic effect, so that the stripping efficiency of the graphene is improved. Meanwhile, it can be seen that when dimethylformamide is replaced with other solvents, the yield of graphene is much lower than that of comparative examples 1 and 4, but is far lower than that of example 2, presumably because CsOH treatment of natural graphene can increase the interlayer spacing of graphene, but such interlayer spacing is only suitable for dimethylformamide molecular size in a supercritical state, and the remaining solvents may be due to the reason of interlayer spacing mismatch or difference in molecular polarity, resulting in reduced efficiency of intercalation between graphene layers, and finally reduced yield of graphene.
TABLE 1 yields of graphene of example 2 and comparative examples 1 and 4-7 were obtained with a visible spectrophotometer at different wavelengths of 480, 540, 600, 660, 720, 780 and 840nm, respectively
Example 3
S1, adding 30ml of solution with the concentration of 0.05mol/L CsOH into a beaker filled with 2.0g of natural graphite powder, continuously stirring by a magnetic stirrer at room temperature for 30 minutes, finally separating solids by a glass filter, washing by reuse deionized water, and drying in a forced air drying box to thoroughly remove water and residual CsOH on the surface of graphite.
S2, adding the natural graphite powder treated in the step S1 into a test tube, adding a corresponding volume of dimethylformamide solution into the test tube, fully mixing the natural graphite powder with the dimethylformamide solvent for 20 minutes by using a low-energy ultrasonic cleaner, carefully transferring the mixture into a stainless steel reactor by using a dropper, heating the closed reactor in a quartz tube furnace at a heating rate of 10 ℃/min, ensuring that the actual temperature of the mixture in the reactor reaches a preset temperature of 400 ℃, and then keeping the temperature for 20 minutes after the actual temperature of the mixture in the reactor reaches the preset temperature;
s3, after the natural graphite is successfully stripped, rapidly cooling the hot reactor in an ice-cold ice-water mixture tank, slowly opening the reactor after the reactor is completely cooled, pouring the product into a test tube, precipitating for a while, performing solid-liquid separation by using a glass suction filter, and cleaning the filter membrane which is an organic polytetrafluoroethylene membrane with deionized water for a plurality of times in the suction filtration process so as to completely clean the residual dimethylformamide;
s4, adding the graphite powder treated by the S3 into a graphite powder filled with 30ml of Na 2 SO 3 And (3) carrying out heating ultrasonic treatment in a glass bottle of the solution, setting ultrasonic parameters to be 50kHz, setting the temperature to be 80 ℃ and the duration to be 20 minutes, and finally, washing the product for multiple times and then putting the product into a vacuum drying oven for drying treatment.
Comparative example 8
Except for not in step S4Adding Na 2 SO 3 Except for this, the rest was the same as in example 3.
Fig. 3 is a raman diagram of graphene prepared in example 3 and comparative example 8 of the present invention, which is used to characterize the quality of graphene, and has no damage to samples. As can be seen from the spectrogram, three characteristic peaks, D peak (1346 cm -1 ) G peak (1575 cm) -1 ) The appearance of the D peak indicates the presence of defects in the carbon material. Ratio of D peak to G peak (I D /I G ) Representing the quality of graphene. Through Na 2 SO 3 Treated graphene I D /I G Is 0.18, which is significantly lower than that of comparative example 8 D /I G Value (0.34). This is because the pure natural graphite is given some impurities after CsOH treatment, so that the impurity content is increased and finally expressed as I D /I G The value increases. Although the supercritical condition (high-temperature and high-pressure environment) can generate the reduction process, the reduction is not very thorough, and residual impurities can influence the quality of the graphene. Through Na 2 SO 3 The treated graphene is reduced with reduced impurity content. Meanwhile, according to the present literature report, example 3, I D /I G The value is far lower than the I of the reduced graphene prepared by reducing the oxidized graphene D /I G The value (0.9-1.4) shows that the defect of graphene obtained by stripping CsOH treated natural graphite by supercritical fluid is less, and the quality is higher.
Fig. 4 and 5 are electronically scanned views of graphene prepared according to example 3 and comparative example 8, respectively, of the present invention. From the scan, it can be seen that the graphene prepared in comparative example 8 has a size ranging from 30 μm to 50 μm, and at the same time, many thin products appear, indicating that the sample obtained in comparative example 8 is a multi-layered graphene. After passing through Na 2 SO 3 The graphene obtained after the treatment was further reduced in size as low as 2 μm-10 μm, and at the same time, a number of extremely thin sheet materials were attached to the large sheet, indicating that the multilayer graphene was subjected to Na 2 SO 3 During treatment, SO 3 2- The partially oxidized graphene is reduced between the infiltration layers, so that the reduction degree of the graphene is ensured, and the graphene is shaped simultaneouslySO formed 4 2- The graphene rich in electrons has an electrostatic repulsion effect, and is favorable for further stripping of graphite, so that single-layer graphene is obtained.
Finally, it should be noted that: the foregoing description is only illustrative of the preferred embodiments of the present invention, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements or changes may be made without departing from the spirit and principles of the present invention.
Claims (10)
1. The method for preparing the low-defect nanoscale graphene by using the physical method is characterized by comprising the following steps of:
s1, adding a solution with the concentration of 0.01-0.05mol/L CsOH into a beaker filled with natural graphite powder, continuously stirring by using a magnetic stirrer at room temperature for 10-50 minutes, finally performing solid separation by using a glass filter, washing by using deionized water in a repeated manner, and drying in a forced air drying box to thoroughly remove water and residual CsOH on the surface of graphite;
s2, adding the natural graphite powder treated in the step S1 into a test tube, adding a corresponding volume of dimethylformamide solution into the test tube, fully mixing the natural graphite powder with the dimethylformamide solvent for 5-30 minutes by using a low-energy ultrasonic cleaner, carefully transferring the mixture into a stainless steel reactor by using a dropper, heating the closed reactor in a quartz tube furnace at a heating rate of 2-10 ℃/min, ensuring that the actual temperature of the mixture in the reactor reaches the preset temperature of 350-450 ℃, and then keeping the temperature for 5-20 minutes after the actual temperature in the reactor reaches the preset temperature;
s3, after the natural graphite is successfully stripped, rapidly cooling the hot reactor in an ice-cold ice-water mixture tank, slowly opening the reactor after the reactor is completely cooled, pouring the product into a test tube, precipitating for a while, performing solid-liquid separation by using a glass suction filter, and cleaning the filter membrane which is an organic polytetrafluoroethylene membrane with deionized water for a plurality of times in the suction filtration process so as to completely clean the residual dimethylformamide;
s4, adding the graphite powder treated by the step S3 into Na 2 SO 3 Heating and ultrasonic treatment is carried out in a glass bottle of the solution, ultrasonic parameters are set to be 30-60kHz, the temperature is 50-80 ℃, and finally, the product is put into a vacuum drying oven for drying treatment after being washed for a plurality of times.
2. The method for preparing low-defect nanoscale graphene by using the physical method according to claim 1, wherein the method comprises the following steps of: the concentration of the CsOH solution in the step S1 is 0.02mol/L, and the volume of the solution is 25ml.
3. The method for preparing low-defect nanoscale graphene by using the physical method according to claim 1, wherein the method comprises the following steps of: the concentration of the CsOH solution in the step S1 is 0.03mol/L, and the volume of the solution is 20ml.
4. A method of physically producing low defect nanoscale graphene according to claim 2 or 3, wherein: the mass of the natural graphite powder in the step S1 is 1.5g, and the stirring time at room temperature is 20 minutes.
5. The method for preparing low-defect nanoscale graphene by using the physical method according to claim 4, wherein the method comprises the following steps of: the volume of the dimethylformamide solution in the step S2 is 4ml.
6. The method for preparing low-defect nanoscale graphene by using the physical method according to claim 5, wherein the method comprises the following steps of: in the step S2, the ultrasonic cleaner is set to 40kHz, and the mixing time is 10 minutes.
7. The method for preparing low-defect nanoscale graphene by using the physical method according to claim 6, wherein the method comprises the following steps of: and in the step S2, the heating rate is 10 ℃/min, and the preset temperature is 350 ℃.
8. The method for preparing low-defect nanoscale graphene by using the physical method according to claim 1, wherein the method comprises the following steps of: the precipitation time of the reactant in the step S3 is 30 minutes.
9. The method for preparing low-defect nanoscale graphene by using the physical method according to claim 8, wherein the method comprises the following steps of: step Na in S4 2 SO 3 The concentration of the solution was 0.05mol/L and the volume of the solution was 25ml.
10. The low-defect graphene prepared by the preparation method of any one of claims 1 to 9.
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