Edge orientation controllable oxidized modified graphene and preparation method thereof

Abstract

The application relates to the technical field of modified graphene, and discloses edge directional controllable oxidation modified graphene and a preparation method thereof, which comprises the following steps: mixing graphene powder, sodium nitrate powder and superfine heavy calcium carbonate powder in a low-humidity sealed air environment to form a ternary composite oxygen source system composed of sodium nitrate, superfine heavy calcium carbonate and normal-pressure dry air; then scanning irradiation is carried out by using an infrared CO2 laser with a wavelength of 10.6 micrometers, so that the edge area of the graphene sheet layer is preferentially oxidized; and finally, the product is obtained through water washing, separation and drying. The application realizes edge directional controllable oxidation by using the dispersion and isolation effect of superfine heavy calcium carbonate between graphene sheet layers and the cooperation of continuous oxygen supplement of air, effectively inhibits excessive oxidation of the basal plane, maintains the sp 2 Carbon skeleton integrity and high conductivity; meanwhile, the molar ratio of the hydroxyl group and the carboxyl group in the edge area can be flexibly regulated by adjusting the ratio of sodium nitrate and heavy calcium carbonate and the laser power, so that the functional modification and the conductivity are considered.

Description

Technical Field

[0001] This invention relates to the field of modified graphene technology, and in particular to an edge-oriented controllable oxidation-modified graphene and its preparation method. Background Technology

[0002] Graphene, as a class of carbon atoms in sp... 2 Two-dimensional honeycomb lattice structures composed of hybrid orbitals have shown broad application prospects in energy storage devices, composite materials, sensing, and catalysis due to their ultra-high electron mobility, excellent mechanical properties, and large specific surface area. However, the surface of structurally intact graphene sheets is chemically inert, and irreversible aggregation easily occurs between sheets due to strong van der Waals forces, severely restricting their uniform dispersion and functionalization applications in polar media and polymer matrices. Therefore, surface modification of graphene to introduce oxygen-containing functional groups has become a research hotspot. Oxygen-containing functional groups can not only significantly improve the hydrophilicity and dispersion stability of graphene, but also serve as reaction sites for subsequent covalent functionalization. Among various modification strategies, edge-selective oxidation has attracted widespread attention because it can impart the required chemical activity to graphene without significantly destroying the sp² conjugated structure of the basal surface, while better preserving the conductivity of the basal surface.

[0003] A search revealed that patent publication number CN115584180A discloses a modified graphene coating with good dispersibility and its preparation method. This patent explicitly states that the modified graphene is obtained through edge-selective oxidation, aiming to imbue the graphene edges with hydrophilic oxygen-containing groups, thereby improving the graphene's dispersion performance in the coating. However, this technical solution mainly relies on traditional electrochemical or chemical oxidation methods, conducting the reaction in a conventional air environment. Due to the lack of effective constraint on the oxidation reaction region, its so-called edge-selective oxidation is difficult to achieve truly preferential oxidation in practice: the oxidizing active material attacks both the higher-energy edge carbon atoms and simultaneously diffuses into the basal surface region, causing non-specific oxidation damage to the basal surface sp² carbon skeleton. This basal surface oxidation leads to a sharp decrease in the conductivity of the modified graphene in practical applications; the sheet resistance can surge from hundreds of ohms per square meter before modification to tens of thousands of ohms per square meter, making the resulting product unsuitable for applications requiring high conductivity, such as conductive composite materials, transparent conductive films, and antistatic coatings. More importantly, existing technologies generally cannot effectively control the types and proportions of oxygen-containing functional groups introduced during the oxidation process. In particular, the molar ratio of hydroxyl to carboxyl groups is often randomly distributed, making it impossible to achieve targeted design according to different functionalization requirements. In addition, traditional oxidation methods often require the introduction of strong acids or strong oxidants, resulting in a large amount of acidic waste liquid generated during subsequent purification processes, leading to poor environmental compatibility and high costs for large-scale production.

[0004] Therefore, there is an urgent need to develop a new technology that can achieve highly selective, directional, and controllable oxidation of the graphene edge region without significantly damaging the graphene basal structure, and can flexibly adjust the molar ratio of hydroxyl to carboxyl groups in the edge region, while taking into account environmental friendliness and process scalability. Summary of the Invention

[0005] The present invention mainly addresses the technical problems existing in the prior art, and provides edge-oriented controllable oxidation-modified graphene and its preparation method.

[0006] To achieve the above objectives, the present invention employs the following technical solution: a method for preparing edge-oriented controllable oxidation-modified graphene, comprising the following steps:

[0007] S1. In a low-humidity, closed air environment with a temperature of 22-26℃ and a relative humidity of no more than 35%, graphene powder is mixed with sodium nitrate powder and ultrafine heavy calcium carbonate powder. The ultrafine heavy calcium carbonate is dispersed between the graphene sheets and forms a solid-phase composite oxygen source together with sodium nitrate. The normal-pressure dry air in the closed environment is used as the gas-phase oxygen source to form a ternary composite oxygen source system composed of sodium nitrate, ultrafine heavy calcium carbonate and normal-pressure dry air, thus obtaining a premixed modified powder.

[0008] S2. The premixed modified powder is continuously and evenly spread on the surface of the conveyor belt and sent into the sealed reaction chamber, where normal pressure dry air is continuously introduced.

[0009] S3. The premixed modified powder is scanned and irradiated with an infrared CO2 laser with a wavelength of 10.6 μm to induce preferential oxidation reaction in the edge region of the graphene sheets, thereby forming an edge-oriented oxidation structure with a higher degree of oxidation in the edge region than in the base region.

[0010] S4. The molar ratio of hydroxyl to carboxyl groups in the edge region is adjusted by regulating the mass ratio of sodium nitrate to ultrafine heavy calcium carbonate, the laser output power, and the irradiation time of the material.

[0011] S5. After laser treatment, the modified graphene is separated from the ultrafine heavy calcium carbonate by water washing, and the ultrafine heavy calcium carbonate and sodium nitrate are recovered from the washing solution. After drying, edge-oriented controllable oxidation modified graphene is obtained.

[0012] Preferably, the graphene powder is natural flake graphene micro powder with a particle size of 2000-5000 mesh and a fixed carbon content of not less than 98%, preferably with a particle size of 3000 mesh and a fixed carbon content of 98.5% or more.

[0013] Preferably, the sodium nitrate powder has a particle size of 600-1000 mesh and a purity of not less than 99.0%; the ultrafine heavy calcium carbonate powder has a particle size of 10000-15000 mesh and a CaCO3 content of not less than 98%.

[0014] Preferably, based on 100 parts by weight of graphene powder, the total amount of the ternary composite oxygen source added is 25 to 45 parts by weight, and the mass ratio of sodium nitrate to ultrafine heavy calcium carbonate is 1:4 to 3:2.

[0015] Preferably, in step S1, a horizontal ribbon mixer is used for mixing, with a mixing speed of 60-70 r / min and a mixing time of 40-50 min.

[0016] Preferably, in step S2, the thickness of the premixed modified powder is 0.7-0.9 mm, the flow rate of the dry air in the sealed reaction chamber is 0.5-1.5 m³ / h, and the dew point of the dry air is not higher than -5°C.

[0017] Preferably, in step S3, the output power of the infrared CO2 laser is 8-21W, the conveyor belt speed is 0.25-1.2m / min, the laser single-point irradiation time is 0.4-2.0s, and the laser adopts a linear array scanning method with the scanning direction perpendicular to the material travel direction.

[0018] Preferably, when the mass ratio of sodium nitrate to ultrafine heavy calcium carbonate is 1:4 to 1:1 and the laser output power is 8 to 13 W, the molar ratio of hydroxyl to carboxyl groups in the edge region of the modified graphene is 9:1 to 5:5. When the mass ratio of sodium nitrate to ultrafine heavy calcium carbonate is 2:3 to 3:2 and the laser output power is 16 to 21 W, the molar ratio of hydroxyl to carboxyl groups in the edge region of the modified graphene is 3:7 to 1:9.

[0019] Preferably, in step S5, deionized water is used for washing, the solid-liquid mass ratio is 1:6 to 1:10, the washing is performed at least twice, and the solid-liquid separation is carried out by filtration, sedimentation or centrifugation. Ultrafine heavy calcium carbonate is recovered by adding quicklime to the washing liquid for precipitation, and sodium nitrate is recovered by concentration and crystallization. The obtained modified graphene is vacuum dried at 50-60°C and a vacuum degree of not less than -0.07 MPa.

[0020] Also provided is an edge-oriented controllable oxidation modified graphene, which is prepared by the preparation method according to any one of claims 2 to 10, comprising a graphene sheet matrix and an edge-enriched oxygen-containing functional group structure.

[0021] The graphene sheet matrix retains sp 2A carbon framework structure, wherein the edge-enriched oxygen-containing functional groups are distributed in the edge region of the graphene sheet;

[0022] The edge-enriched oxygen-containing functional group structure includes hydroxyl and carboxyl groups, with a molar ratio of hydroxyl to carboxyl groups of 9:1 to 1:9;

[0023] The ratio of oxygen content in the edge region to oxygen content in the base region is 5.6 to 11.2.

[0024] Beneficial effects

[0025] This invention provides edge-oriented controllable oxidation-modified graphene and its preparation method. It has the following beneficial effects:

[0026] (1) The edge-oriented controllable oxidation-modified graphene and its preparation method propose a ternary composite oxygen source system composed of sodium nitrate, ultrafine heavy calcium carbonate and normal pressure dry air. The dispersion and isolation effect of ultrafine heavy calcium carbonate between graphene sheets and the continuous oxygen replenishment effect of air are used to achieve synergistic regulation of oxidation reaction activity, thereby ensuring oxidation efficiency while inhibiting excessive oxidation of graphene substrate and improving oxidation selectivity in edge region.

[0027] (2) This invention relates to edge-oriented controllable oxidation modification of graphene and its preparation method. It proposes a continuous directional modification process using infrared CO2 laser as the edge oxidation trigger source. By coupling the composite oxygen source system with the laser irradiation process and coordinating the oxygen source composition, laser energy input, and material residence time, preferential oxidation of the graphene sheet edge region is achieved, while maintaining the basal surface sp... 2 While maintaining the stability of the carbon framework structure, an edge-enriched oxygen-containing functional group structure is constructed, thereby balancing the need to maintain electrical conductivity and the need for surface functionalization modification.

[0028] (3) This edge-oriented controllable oxidation modified graphene and its preparation method propose a modified graphene preparation mechanism with adjustable edge functional group composition. By adjusting the ratio of ternary composite oxygen source and laser intensity, the ratio of hydroxyl and carboxyl groups in the edge region can be continuously controlled. The corresponding relationship between functional group composition and material conductivity and water dispersibility is established. At the same time, combined with the auxiliary agent recycling process, the product performance can be customized and the production process can be optimized in a synergistic way with low consumption and low waste emissions. Attached Figure Description

[0029] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0030] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] A method for preparing edge-oriented controllable oxidation-modified graphene, such as Figure 1 As shown, it includes the following steps:

[0033] S1. In a low-humidity, closed air environment with a temperature of 22-26℃ and a relative humidity of no more than 35%, graphene powder is mixed with sodium nitrate powder and ultrafine heavy calcium carbonate powder. The ultrafine heavy calcium carbonate is dispersed between the graphene sheets and forms a solid-phase composite oxygen source together with sodium nitrate. The normal-pressure dry air in the closed environment is used as the gas-phase oxygen source to form a ternary composite oxygen source system composed of sodium nitrate, ultrafine heavy calcium carbonate and normal-pressure dry air, thus obtaining a premixed modified powder.

[0034] S2. The premixed modified powder is continuously and evenly spread on the surface of the conveyor belt and sent into the sealed reaction chamber, where normal pressure dry air is continuously introduced.

[0035] S3. The premixed modified powder is scanned and irradiated with an infrared CO2 laser with a wavelength of 10.6 μm to induce preferential oxidation reaction in the edge region of the graphene sheets, thereby forming an edge-oriented oxidation structure with a higher degree of oxidation in the edge region than in the base region.

[0036] S4. The molar ratio of hydroxyl to carboxyl groups in the edge region is adjusted by regulating the mass ratio of sodium nitrate to ultrafine heavy calcium carbonate, the laser output power, and the irradiation time of the material.

[0037] S5. After laser treatment, the modified graphene is separated from the ultrafine heavy calcium carbonate by water washing, and the ultrafine heavy calcium carbonate and sodium nitrate are recovered from the washing solution. After drying, edge-oriented controllable oxidation modified graphene is obtained.

[0038] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0039] Example 1

[0040] This embodiment illustrates the method of preparing highly hydroxyl-type edge-oriented controllable oxidation-modified graphene under low oxidation intensity conditions according to the present invention.

[0041] Natural flake graphene powder with a particle size of 3000 mesh was selected as the raw material, with a fixed carbon content of 98.5%. In a closed, dry air environment at 22℃ and 35% relative humidity, 25 parts by mass of a ternary composite oxygen source were added to 100 parts by mass of graphene powder, with a sodium nitrate to ultrafine heavy calcium carbonate mass ratio of 1:4. The mixture was then applied using a horizontal ribbon mixer at a mixing speed of 60 r / min for 40 min to obtain a premixed modified powder.

[0042] The premixed modified powder is then continuously conveyed onto a stainless steel mesh belt via a closed screw feeder, with the thickness of the material controlled at 0.7 mm. Dry air with a dew point not exceeding -5°C is continuously introduced into the reaction chamber at an air replacement flow rate of 0.5 m³ / h.

[0043] A CO2 laser with a wavelength of 10.6 μm was used to perform linear array scanning irradiation on the laid material. The laser power was 8W, the conveyor belt speed was 1.2 m / min, and the corresponding single-point irradiation time was about 0.4 s.

[0044] After laser treatment, the product was washed twice with deionized water at a solid-liquid mass ratio of 1:10, followed by solid-liquid separation by centrifugation. The resulting powder was then vacuum-dried at 50°C and a vacuum degree of not less than -0.07 MPa to obtain edge-oriented controllable oxidation-modified graphene.

[0045] X-ray photoelectron spectroscopy (XPS) analysis revealed that the edge region of the obtained sample was enriched with hydroxyl functional groups, with a hydroxyl to carboxyl molar ratio of approximately 9:1 and an oxygen / carbon atomic ratio (O / C) of approximately 0.082. Raman spectroscopy results showed an ID / IG value of approximately 0.18, indicating that the graphene basal surface sp 2 The carbon framework maintains a high degree of integrity. Comparative analysis of oxygen content between the edge and basal regions revealed that the oxygen content in the edge region is approximately 5.6 times that in the basal region, indicating that the oxidation reaction is mainly concentrated in the lamellar edge region.

[0046] Example 2

[0047] This embodiment illustrates the method of preparing edge-oriented controllable oxidation-modified graphene with a balanced ratio of edge hydroxyl to carboxyl groups under preferred process conditions according to the present invention.

[0048] Natural flake graphene powder with a particle size of 3000 mesh was selected as raw material. In a closed air environment at 24℃ and 30% relative humidity, 35 parts by mass of a ternary composite oxygen source were added based on 100 parts by mass of graphene powder, with a mass ratio of sodium nitrate to ultrafine heavy calcium carbonate of 1:1. Mixing was performed using a horizontal ribbon mixer at a mixing speed of 65 r / min for 45 min.

[0049] The obtained premixed modified powder is continuously laid on the surface of the conveyor belt through a closed feeding device, with the thickness of the material controlled at 0.8 mm. Dry air with a dew point not higher than -5℃ is continuously introduced into the reaction chamber, with an air replacement flow rate of 0.8 m³ / h.

[0050] A 10.6 μm wavelength CO2 laser was used for linear array scanning. The laser power was 13 W, the conveyor belt speed was 0.6 m / min, and the corresponding single-point irradiation time was about 0.77 s.

[0051] After laser treatment, the sample was washed twice with deionized water at a solid-liquid mass ratio of 1:8 and then filtered for separation. The resulting sample was dried at 55℃ and a vacuum degree of not less than -0.07MPa for 3.5h.

[0052] Test results show that the molar ratio of hydroxyl to carboxyl groups in the edge region of the modified graphene is approximately 5:5, and the oxygen-to-carbon atom ratio is approximately 0.138. Raman spectroscopy results show an ID / IG value of approximately 0.29. The oxygen content in the edge region is approximately 8.4 times that in the basal region, indicating that a significant edge-oriented oxidation effect can be obtained under these process conditions, while maintaining the basic integrity of the graphene basal structure.

[0053] Example 3

[0054] This embodiment illustrates the method of preparing highly carboxyl-based edge-oriented controllable oxidatively modified graphene under high oxidative intensity conditions according to the present invention.

[0055] Natural flake graphene powder with a particle size of 3000 mesh was selected as raw material. In a closed air environment at 26℃ and 25% relative humidity, 45 parts by mass of ternary composite oxygen source were added based on 100 parts by mass of graphene powder, wherein the mass ratio of sodium nitrate to ultrafine heavy calcium carbonate was 3:2. A horizontal ribbon mixer was used for mixing at a mixing speed of 70 r / min for 50 min.

[0056] After closed-loop feeding, the premixed modified powder is evenly spread on the surface of the conveyor belt to a thickness of 0.9 mm. Dry air with a dew point not higher than -5℃ is continuously introduced into the reaction chamber, and the air flow rate is controlled at 1.5 m³ / min. 3 / h.

[0057] A 10.6 μm wavelength CO2 laser was used for linear array scanning. The laser output power was 21 W, the conveyor belt speed was 0.25 m / min, and the corresponding single-point irradiation time was about 2.0 s.

[0058] After treatment, the solid-liquid mass ratio was 1:6, and the product was washed three times with deionized water. After filtration, it was vacuum dried at 60°C and a vacuum degree of not less than -0.07MPa.

[0059] Test results show that the carboxyl content in the edge region of the obtained sample is significantly increased, with a molar ratio of hydroxyl to carboxyl groups of approximately 1:9 and an oxygen-to-carbon atom ratio of approximately 0.247. Raman spectroscopy results show an ID / IG value of approximately 0.46. The oxygen content in the edge region is approximately 11.2 times that in the basal region, indicating that the oxidation reaction is further concentrated in the edge region, but the graphene basal structure is not significantly damaged.

[0060] Comparative Example 1

[0061] Except for the absence of ultrafine heavy calcium carbonate, the other process conditions were the same as in Example 2.

[0062] Test results showed that the oxygen-to-carbon atomic ratio of the obtained sample was approximately 0.141, and the Raman ID / IG value was approximately 0.71. Scanning electron microscopy revealed that oxidation areas appeared simultaneously in both the edge and basal regions, with localized ablation pits and lamellar damage. The oxygen content ratio in the edge region to that in the basal region was approximately 1.9, significantly lower than in Example 2.

[0063] Comparative Example 2

[0064] Except for the absence of sodium nitrate, the other process conditions were the same as in Example 2.

[0065] Test results show that the oxygen-to-carbon atom ratio of the obtained sample is about 0.038, the number of oxygen-containing functional groups formed in the edge region is significantly reduced, and the ratio of oxygen content in the edge region to oxygen content in the basal region is about 2.3, indicating that it is difficult to achieve effective edge oxidation by relying solely on air and ultrafine heavy calcium carbonate.

[0066] Comparative Example 3

[0067] The same raw material composition and process conditions as in Example 2 were used, but without laser irradiation treatment, and the mixture was simply left to stand in a closed air environment for 72 hours.

[0068] Test results show that the oxygen-to-carbon atom ratio of the obtained sample is approximately 0.011, no obvious new oxygen-containing functional groups were detected, and the ratio of oxygen content in the edge region to oxygen content in the basal region is approximately 1.1, indicating that in the system of this invention, laser irradiation is an important condition for triggering the edge oxidation reaction.

[0069] Comparative Example 4

[0070] The same raw material composition and process conditions as in Example 2 were used, but the dry air in the reaction chamber was replaced with nitrogen.

[0071] Test results showed that the oxygen-to-carbon atomic ratio of the obtained sample was approximately 0.081, and the ratio of oxygen content in the edge region to oxygen content in the base region was approximately 4.7, both lower than in Example 2, indicating that continuous air replenishment can further improve the degree of edge oxidation.

[0072] Comparative Example 5

[0073] A graphene oxide sample prepared using a traditional graphene oxide preparation process was used as a control.

[0074] Test results show that the oxygen-to-carbon atom ratio of the obtained sample is approximately 0.42, and the Raman ID / IG value is approximately 1.03. Electron microscopy revealed that a large number of oxidized structures are distributed in the graphene basal region, and the oxygen content ratio of the edge region to the basal region is approximately 1.2. This indicates that traditional oxidation processes easily cause damage to the graphene basal structure, while this invention can achieve directional oxidation modification mainly in the edge region.

[0075] Table 1. Effect of ultrafine heavy calcium carbonate on edge-oriented oxidation

[0076]

[0077] As shown in Table 1, although the overall oxidation degree is similar without the addition of ultrafine heavy calcium carbonate, the ratio of edge oxygen content to basal oxygen content decreases significantly, while ID / IG increases significantly. This indicates that ultrafine heavy calcium carbonate can effectively inhibit disordered oxidation of the basal surface and promote preferential oxidation of the edge.

[0078] Table 2 Verification results of laser triggering effect

[0079]

[0080] As shown in Table 2, under the same raw material system, no obvious oxidation reaction occurred when laser irradiation was not performed, indicating that laser irradiation is an important condition for triggering edge oxidation reaction.

[0081] Table 3 Performance comparison with traditional graphene oxide

[0082]

[0083] As shown in Table 3, traditional oxidation processes result in a large number of oxidized structures distributed in the graphene basal region, which significantly damages the sp² carbon skeleton. In contrast, the present invention can achieve edge-preferred oxidation, which introduces oxygen-containing functional groups while maintaining the integrity of the basal structure, thereby balancing the requirements of conductivity and functional modification.

[0084] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing edge-oriented controllable oxidation-modified graphene, characterized in that, Includes the following steps: S1. In a low-humidity, closed air environment with a temperature of 22-26℃ and a relative humidity of no more than 35%, graphene powder is mixed with sodium nitrate powder and ultrafine heavy calcium carbonate powder. The ultrafine heavy calcium carbonate is dispersed between the graphene sheets and forms a solid-phase composite oxygen source together with sodium nitrate. The dry air at normal pressure in the closed environment is used as the gas-phase oxygen source to form a ternary composite oxygen source system composed of sodium nitrate, ultrafine heavy calcium carbonate and dry air at normal pressure, thus obtaining a premixed modified powder. S2. The premixed modified powder is continuously and evenly spread on the surface of the conveyor belt and sent into the sealed reaction chamber, where normal pressure dry air is continuously introduced. S3. The premixed modified powder is scanned and irradiated with an infrared CO2 laser with a wavelength of 10.6 μm to induce preferential oxidation reaction in the edge region of the graphene sheets, thereby forming an edge-oriented oxidation structure with a higher degree of oxidation in the edge region than in the base region. S4. The molar ratio of hydroxyl to carboxyl groups in the edge region is adjusted by regulating the mass ratio of sodium nitrate to ultrafine heavy calcium carbonate, the laser output power, and the irradiation time of the material. S5. After laser treatment, the modified graphene is separated from the ultrafine heavy calcium carbonate by water washing, and the ultrafine heavy calcium carbonate and sodium nitrate are recovered from the washing solution. After drying, edge-oriented controllable oxidation modified graphene is obtained.

2. The method for preparing edge-oriented controllable oxidation-modified graphene according to claim 1, characterized in that: The graphene powder is natural flake graphene micro powder with a particle size of 2000-5000 mesh and a fixed carbon content of not less than 98%, preferably with a particle size of 3000 mesh and a fixed carbon content of 98.5% or more.

3. The method for preparing edge-oriented controllable oxidation-modified graphene according to claim 1, characterized in that: The sodium nitrate powder has a particle size of 600-1000 mesh and a purity of not less than 99.0%; the ultrafine heavy calcium carbonate powder has a particle size of 10000-15000 mesh and a CaCO3 content of not less than 98%.

4. The method for preparing edge-oriented controllable oxidation-modified graphene according to claim 1, characterized in that: Based on 100 parts by weight of graphene powder, the total amount of the ternary composite oxygen source added is 25 to 45 parts by weight, and the mass ratio of sodium nitrate to ultrafine heavy calcium carbonate is 1:4 to 3:

2.

5. The method for preparing edge-oriented controllable oxidation-modified graphene according to claim 1, characterized in that: In step S1, a horizontal ribbon mixer is used for mixing, with a mixing speed of 60-70 r / min and a mixing time of 40-50 min.

6. The method for preparing edge-oriented controllable oxidation-modified graphene according to claim 1, characterized in that: In step S2, the thickness of the premixed modified powder is 0.7-0.9 mm, the flow rate of dry air in the sealed reaction chamber is 0.5-1.5 m³ / h, and the dew point of the dry air is not higher than -5°C.

7. The method for preparing edge-oriented controllable oxidation-modified graphene according to claim 1, characterized in that: In step S3, the output power of the infrared CO2 laser is 8-21W, the conveyor belt speed is 0.25-1.2m / min, the laser single-point irradiation time is 0.4-2.0s, and the laser adopts a linear array scanning method with the scanning direction perpendicular to the material travel direction.

8. The method for preparing edge-oriented controllable oxidation-modified graphene according to claim 1, characterized in that: When the mass ratio of sodium nitrate to ultrafine heavy calcium carbonate is 1:4 to 1:1 and the laser output power is 8 to 13 W, the molar ratio of hydroxyl to carboxyl groups in the edge region of the modified graphene is 9:1 to 5:

5. When the mass ratio of sodium nitrate to ultrafine heavy calcium carbonate is 2:3 to 3:2 and the laser output power is 16 to 21 W, the molar ratio of hydroxyl to carboxyl groups in the edge region of the modified graphene is 3:7 to 1:

9.

9. The method for preparing edge-oriented controllable oxidation-modified graphene according to claim 1, characterized in that: In step S5, deionized water is used for washing, with a solid-liquid mass ratio of 1:6 to 1:

10. The washing is performed at least twice. Solid-liquid separation is achieved by filtration, sedimentation, or centrifugation. Ultrafine heavy calcium carbonate is recovered by adding quicklime to the washing solution for precipitation. Sodium nitrate is recovered by concentration and crystallization. The resulting modified graphene is vacuum dried at 50–60°C and a vacuum degree of not less than -0.07 MPa.

10. An edge-oriented, controllable oxidation-modified graphene, characterized in that: The edge-oriented controllable oxidation-modified graphene is prepared by the preparation method described in any one of claims 1 to 9, and includes a graphene sheet matrix and an edge-enriched oxygen-containing functional group structure. The graphene sheet matrix retains sp 2 A carbon framework structure, wherein the edge-enriched oxygen-containing functional groups are distributed in the edge region of the graphene sheet; The edge-enriched oxygen-containing functional group structure includes hydroxyl and carboxyl groups, with a molar ratio of hydroxyl to carboxyl groups of 9:1 to 1:9; The ratio of oxygen content in the edge region to oxygen content in the base region is 5.6 to 11.2.

Images