Method for recycling graphene electron microscope grid

Abstract

The present application relates to the technical field of graphene material, in particular to a recycling method of graphene electron microscope grid, which comprises the following steps: screening the recyclable grid, carrying out plasma cleaning, under the premise of not damaging the expensive metal support grid, controllably removing the original low coverage graphene, and the removal rate is 100%. After cleaning, the grid is soaked in an organic solvent to remove the surface organic pollutants, obtain a clean grid body, and soften the grid support film, which is helpful to the effective later-stage adhesion of the grid support film and graphene. The coverage rate of the surface graphene of the re-transferred graphene grid reaches 98%. The grid body is placed on the front surface of the foil graphene to form a grid / graphene / foil metal substrate combination, which is placed on the liquid surface of the etching liquid to float and etch the metal substrate of the foil graphene to obtain a grid / graphene combination. Finally, the combination is transferred to deionized water for cleaning, and dried to obtain a re-transferred graphene electron microscope grid. The grid can be repeatedly used, saving cost.

Description

Technical Field

[0001] This invention relates to the field of graphene materials technology, specifically to a method for recycling and regenerating graphene electron microscope screens. Background Technology

[0002] Graphene is widely considered an ideal material for sample support films in transmission electron microscopy (TEM) due to its single-atom-layer thickness, high mechanical strength, high electrical conductivity, high thermal conductivity, and excellent chemical stability. Current processes typically involve chemical vapor deposition (CVD) of graphene followed by a wet or dry transfer onto the surface of a support substrate (such as Quantifoil) to prepare graphene electron microscope substrates.

[0003] However, in actual production, due to defects in graphene raw materials, surface contamination, and fluctuations in the transfer process, the graphene coverage on the substrate often fails to reach the ideal level, failing to meet the requirements for cryo-electron microscopy sample preparation and resulting in defective products. This leads to a double waste of graphene material and metal substrate, and significantly increases production costs.

[0004] Currently, the industry typically handles substandard graphene webs by simply discarding them, lacking effective recycling and regeneration technologies. Simple physical cleaning methods (such as solvent rinsing and ultrasonic cleaning) cannot effectively remove the attached graphene and easily damage the delicate microporous structure of the metal support web.

[0005] However, if drastic chemical treatments are used or direct re-transfer is attempted, not only may the original graphene fail to be completely removed, but new chemical contamination or physical damage (such as wrinkles and cracks) may also be introduced, failing to meet the high requirements for cleanliness and integrity of electron microscope screens.

[0006] A Chinese invention patent, titled "Graphene Modification" with patent application number 201480055929.2, discloses a technical solution for using plasma technology to treat the surface of graphene. However, the main purpose of this patent solution is to remove contaminants or change the surface chemical properties, rather than to remove graphene with low coverage on the support mesh. Therefore, there is an urgent need in the field for a technical solution that can controllably remove graphene with low coverage and re-transfer graphene without damaging the support mesh or introducing additional contamination, so as to achieve the recycling and regeneration of substandard graphene electron microscopy support meshes. Summary of the Invention

[0007] The purpose of this invention is to provide a method for recycling and regenerating graphene electron microscope (TEM) carriers to solve the problems mentioned in the background art. This invention uses plasma cleaning followed by immersion in an organic solvent to obtain a clean carrier. Without damaging the carrier or introducing additional pollution, low-coverage graphene can be controllably removed, and a new continuous graphene film can be transferred to the same carrier surface. This restores the defective carrier to a reusable state with a graphene coverage of ≥85%, which has the advantages of greatly reducing raw material waste and saving production costs.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for recycling and regenerating graphene electron microscope (TEM) support mesh, comprising the following steps: Step 1: Screening for recyclable netting: Using an optical microscope, unqualified netting that meets recycling standards is screened out; the unqualified netting is then recycled, achieving green circular reuse. This greatly saves production costs and improves energy efficiency.

[0009] Step Two: Cleaning and Soaking the Graphite Carrier: The substandard graphite carrier from Step One is first cleaned using plasma cleaning. After cleaning, it is soaked in an organic solvent to obtain a clean carrier. Plasma cleaning can controllably remove the original low-coverage graphene without damaging the expensive metal support carrier, with a removal efficiency of 100%. Soaking in the organic solvent not only removes organic contaminants from the carrier surface but also softens the carrier support film, which helps the carrier support film and graphene to adhere effectively in the later stages. The re-transferred graphene carrier has a surface graphene coverage of 98%.

[0010] Step 3: Pretreatment of foil graphene: The foil graphene is subjected to plasma treatment to remove the graphene on the back side, resulting in foil graphene that retains the graphene on the front side; only the graphene on the front side is retained for transfer, resulting in high transfer efficiency.

[0011] Step 4: Placement: Place the carrier obtained in Step 2 on the front side of the foil graphene obtained in Step 3 to form a combination of carrier / graphene / foil metal substrate. Step 5: Etching: Place the foil graphene carrying the carrier from Step 4 on the surface of the etching solution, and float the metal substrate of the foil graphene to obtain the carrier / graphene combination; floating etching achieves efficient removal of the metal substrate while ensuring that the graphene on the front side is not contaminated, thus completing the transfer of graphene from the metal substrate to the carrier substrate.

[0012] Step Six: Cleaning, Drying, and Re-transferring the Graphene Support: The support obtained in Step Five is transferred to deionized water for cleaning and then dried to obtain a re-transferred graphene electron microscopy support.

[0013] As a further aspect of the present invention, in step 1, the recycling standard for substandard carrier nets is that the surface of the carrier net is visually inspected to be flat, the number of damaged carbon film squares under a light microscope does not exceed 2% of the total number of squares, and the location of the carbon film damage is not within a circle with a diameter of 1.5 mm centered on the center. By comparing with the recycling standard, substandard carrier nets are recycled, effectively improving the energy recovery rate.

[0014] As a further embodiment of the present invention, in step two, the grid is placed on a clean glass slide, with the porous membrane side of the grid in direct contact with the glass slide and the metal substrate side of the grid exposed. The glass slide carrying the grid is then placed in a plasma cleaner and cleaned under set parameters: an air flow rate of 5 sccm to 30 sccm, a power of 20 W to 100 W, and a processing time of 10 s to 150 s, to remove the low-coverage graphene layer within the suspended pores of the grid. Plasma cleaning efficiently removes residual graphene from the grid pores for secondary transfer.

[0015] As a further embodiment of the present invention, in step two, the plasma-cleaned substrate is unloaded from the glass slide, and then immersed in an organic solvent for 1 to 10 hours. The organic solvent is specifically isopropanol, acetone, or ethanol. Acetone dissolves photoresist and polymer residues, while ethanol or isopropanol dissolves moisture and small organic molecule impurities and does not react with the graphene itself; these impurities can be removed by evaporation after cleaning. This provides further cleaning of the substrate surface.

[0016] As a further embodiment of the present invention, in step three, the foil graphene includes a metal substrate and a graphene film grown on the metal substrate by chemical vapor deposition (CVD). The metal substrate may be made of copper, nickel, molybdenum or copper-nickel alloy, and the thickness of the metal substrate is 10 μm to 50 μm. Graphene films can be single-layer monocrystalline graphene layers with large domain regions, double-layer graphene layers, or 2-5 layers of graphene.

[0017] As a further embodiment of the present invention, the carrier mesh can be a microgrid made of gold mesh (Au), copper mesh (Cu), or nickel mesh (Ni), and the porous membrane can be a porous carbon membrane or a porous nickel-titanium membrane.

[0018] As a further embodiment of the present invention, in step four, the carrier is arranged in an array on the foil graphene, the porous membrane is in direct contact with the graphene, and the metal substrate of the carrier is exposed to the atmosphere with its surface facing upwards.

[0019] As a further embodiment of the present invention, in step five, the etching solution includes an etchant, which is sodium persulfate, ferric chloride or sodium ammonium persulfate, the concentration of the etchant in the etching solution is 0.05 to 1 mol / L, and the etching time is 0.5 to 5 h.

[0020] As a further embodiment of the present invention, in step six, the resistivity of the deionized water is 18.25 MΩ·cm, and the washing is performed 3 to 4 times, with each washing session lasting 10 to 60 minutes.

[0021] As a further embodiment of the present invention, in step six, the graphene electron microscope screen is obtained by natural drying, and the graphene coverage on the screen is as high as 97% to 98%.

[0022] Compared with the prior art, the beneficial effects of the present invention are: this system includes several steps for recycling and regeneration. It has the following advantages. (1) Unqualified carrier nets that meet recycling standards are screened using an optical microscope; this enables the recycling of carrier nets, allowing the supporting carrier nets (such as metal bottom nets) to be reused multiple times, avoiding material waste caused by traditional scrapping. Based on a typical production batch, this method can reduce production costs by approximately 10%, which aligns with the concept of green manufacturing.

[0023] (2) The substandard graphene carriers are first cleaned using plasma cleaning. Plasma cleaning efficiently removes residual graphene from the pores of the carrier for secondary transfer. Plasma cleaning allows for the controlled removal of the original low-coverage graphene without damaging the expensive metal support carrier, achieving a 100% removal efficiency. Immersion in an organic solvent not only removes organic contaminants from the carrier surface but also softens the carrier support film, facilitating effective bonding between the carrier support film and the graphene in the later stages. The re-transferred graphene carrier has a 98% graphene coverage on its surface.

[0024] (3) After cleaning, the substrate is immersed in an organic solvent to obtain a clean substrate; the organic solvent is specifically isopropanol, acetone, or ethanol. Acetone dissolves photoresist and polymer residues, while ethanol or isopropanol can dissolve water and small organic molecule impurities and will not react with the graphene itself, so they can be removed by evaporation after cleaning. This provides further cleaning of the substrate surface.

[0025] (4) The foil graphene is subjected to plasma treatment to remove the back side graphene, resulting in foil graphene with the front side graphene retained; only the front side graphene is retained for transfer, resulting in high transfer efficiency.

[0026] (5) The foil graphene carrying the carrier is placed on the surface of the etching solution, and the metal substrate of the foil graphene is floated and etched to obtain the carrier / graphene combination; the floating etching realizes the efficient removal of the metal substrate to complete the transfer of graphene from the metal substrate to the carrier substrate while ensuring that the graphene on the front side is not contaminated.

[0027] (6) Finally, the graphene carrier is transferred to deionized water for cleaning and then dried to obtain a re-transferred graphene electron microscopy carrier. A high-quality graphene carrier with a graphene coverage of 97% to 98% and a clean surface with extremely high coverage is obtained.

[0028] (7) The recycling and regeneration method is simple in process, and the required equipment (such as plasma cleaner) and retransfer process are highly compatible with conventional graphene carrier production lines, making it easy to scale up. Attached Figure Description

[0029] Figure 1 This is a process flow diagram of the recycling and regeneration method of the present invention; Figure 2 These are optical microscope images of the present invention. The left side shows a screen that meets the recycling standards, and the right side shows a screen that does not meet the recycling standards. Figure 3 The image shows a comparison of the plasma processing grid before and after processing according to the present invention; the left image is before processing, and the right image is after processing. Figure 4 In this invention, after the metal substrate is etched, the graphene film carrying the mesh floats on the surface of the etching solution. Figure 5 This is a SEM image of the graphene screen transferred again after plasma treatment according to the present invention. Figure 6 This is an AFM characterization image of the graphene mesh transferred again after plasma treatment according to the present invention. Figure 7 This is a SEM image of the untreated, re-transferred graphene mesh from the present invention. Figure 8 This is an AFM characterization image of the re-transferred graphene mesh without plasma treatment according to the present invention. Detailed Implementation

[0030] 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. Example 1

[0031] Please see the appendix Figure 1 A method for recycling and regenerating graphene electron microscopy (EM) web includes the following steps: Step 1: Screening for Recyclable Screening Materials: Using an optical microscope, unqualified screening materials that meet recycling standards are screened. The recycling standards for unqualified screening materials are: visually inspected surface flatness; under the optical microscope, the number of damaged carbon film squares does not exceed 2% of the total number of squares; and the location of the carbon film damage is not within a circle with a diameter of 1.5 mm centered on the screen's center. By comparing against the recycling standards, unqualified screening materials are screened out for recycling, achieving the recycling and reuse of screening materials. Please refer to the appendix. Figure 2 Optical microscope images: the left side shows a screen that meets the recycling standards, and the right side shows a screen that does not meet the recycling standards.

[0032] Step Two: Cleaning and Soaking the Textile: The defective textile from Step One will be cleaned using plasma cleaning; please refer to the appendix. Figure 3 A comparison of the plasma-treated grid before and after treatment: the left image shows the state before treatment, and the right image shows the state after treatment.

[0033] The mesh is placed on a clean glass slide. The mesh can be a microgrid made of gold (Au), copper (Cu), or nickel (Ni) mesh. The porous membrane side of the mesh is in direct contact with the glass slide. The porous membrane is a porous carbon membrane. The metal substrate side of the mesh is exposed.

[0034] A glass slide carrying a graphite grid is placed in a plasma cleaner and cleaned under the set parameters: air flow rate of 5 sccm, power of 20W, and processing time of 20 seconds. This removes the low-coverage graphene layer within the suspended holes of the graphite grid. Plasma cleaning efficiently removes residual graphene from the grid holes for secondary transfer.

[0035] After cleaning, the substrate is immersed in an organic solvent to obtain a clean substrate. The plasma-cleaned substrate is then unloaded from the glass slide and immersed in an organic solvent, specifically isopropanol, acetone, or ethanol, for 2 hours. Acetone dissolves photoresist and polymer residues, while ethanol or isopropanol dissolves moisture and small organic molecule impurities without reacting with the graphene itself; these impurities can be removed by evaporation after cleaning. This provides further cleaning of the substrate surface.

[0036] Step 3: Pretreatment of foil graphene: The foil graphene is subjected to plasma treatment to remove the graphene on the back side, resulting in foil graphene that retains the graphene on the front side. The foil graphene includes a metal substrate and a graphene film grown on the metal substrate by chemical vapor deposition (CVD). The metal substrate may be made of copper, nickel, molybdenum or copper-nickel alloy and has a thickness of 10 μm. Graphene films can be single-layer monocrystalline graphene layers with large domain regions, double-layer graphene layers, or 2-5 layers of graphene.

[0037] Step 4: Placement: Place the carrier obtained in Step 2 on the front side of the foil graphene obtained in Step 3 to form a combination of carrier / graphene / foil metal substrate; the carrier is placed in an array on the foil graphene, the porous membrane is in direct contact with the graphene, and the metal substrate of the carrier is exposed to the atmosphere with its surface facing upwards.

[0038] Step 5: Etching: Place the graphene foil carrying the grid from Step 4 onto the surface of the etching solution. The etching solution includes an etchant, which can be sodium persulfate, ferric chloride, or sodium ammonium persulfate. The concentration of the etchant in the etching solution is 0.05 g / L, and the etching time is 0.5 h. The metal substrate of the floating graphene foil is etched to obtain a grid / graphene combination. Floating etching achieves efficient removal of the metal substrate while ensuring that the graphene on the front side is not contaminated, thus completing the transfer of graphene from the metal substrate to the grid substrate.

[0039] Please see the appendix Figure 4 After the metal substrate is etched, the graphene film carrying the grid floats on the surface of the etching solution.

[0040] Step Six: Cleaning and Drying. The graphene carrier was transferred again: The carrier obtained in Step Five was transferred to deionized water for cleaning. The resistivity of deionized water is 18.25 MΩ·cm. The cleaning was performed 3 times, with each cleaning lasting 20 min.

[0041] The graphene electron microscope (EM) mesh was then dried to obtain a re-transferred graphene EEM mesh. Natural drying yielded a re-transferred graphene EEM mesh with a graphene coverage of up to 98%. Please refer to the appendix. Figure 5 - Appendix Figure 6 SEM and AFM characterization images of graphene transferred after plasma treatment. Example 2

[0042] Please see the appendix Figure 1 A method for recycling and regenerating graphene electron microscopy (EM) web includes the following steps: Step 1: Screening for Recyclable Screening Materials: Using an optical microscope, unqualified screening materials that meet recycling standards are screened. The recycling standards for unqualified screening materials are: visually inspected surface flatness; under the optical microscope, the number of damaged carbon film squares does not exceed 2% of the total number of squares; and the location of the carbon film damage is not within a circle with a diameter of 1.5 mm centered on the screen's center. By comparing against the recycling standards, unqualified screening materials are screened out for recycling, achieving the recycling and reuse of screening materials. Please refer to the appendix. Figure 2 Optical microscope images: the left side shows a screen that meets the recycling standards, and the right side shows a screen that does not meet the recycling standards.

[0043] Step Two: Cleaning and Soaking the Textile: The defective textile from Step One will be cleaned using plasma cleaning; please refer to the appendix. Figure 3 A comparison of the plasma-treated grid before and after treatment: the left image shows the state before treatment, and the right image shows the state after treatment.

[0044] The mesh is placed on a clean glass slide. The mesh can be a microgrid made of gold (Au), copper (Cu), or nickel (Ni) mesh. The porous membrane side of the mesh is in direct contact with the glass slide. The porous membrane is a porous nickel-titanium membrane. The metal substrate side of the mesh is exposed.

[0045] A glass slide carrying a graphite grid is placed in a plasma cleaner and cleaned under the set parameters: air flow rate of 30 sccm, power of 80 W, and processing time of 140 s. This removes the low-coverage graphene layer within the suspended holes of the graphite grid. Plasma cleaning efficiently removes residual graphene from the grid holes for secondary transfer.

[0046] After cleaning, the substrate is immersed in an organic solvent to obtain a clean grid. The plasma-cleaned grid is then unloaded from the glass slide and immersed in an organic solvent, specifically isopropanol, acetone, or ethanol, for 8 hours. Acetone dissolves photoresist and polymer residues, while ethanol or isopropanol dissolves moisture and small organic molecule impurities without reacting with the graphene itself; these impurities can be removed by evaporation after cleaning. This provides further cleaning of the grid surface.

[0047] Step 3: Pretreatment of foil graphene: The foil graphene is subjected to plasma treatment to remove the graphene on the back side, resulting in foil graphene that retains the graphene on the front side. The foil graphene includes a metal substrate and a graphene film grown on the metal substrate by chemical vapor deposition (CVD). The metal substrate may be made of copper, nickel, molybdenum or copper-nickel alloy and has a thickness of 30 μm. The graphene film is a single-layer monocrystalline graphene layer with a large domain region, a double-layer graphene layer, or a four-layer graphene layer.

[0048] Step 4: Placement: Place the carrier obtained in Step 2 on the front side of the foil graphene obtained in Step 3 to form a combination of carrier / graphene / foil metal substrate; the carrier is placed in an array on the foil graphene, the porous membrane is in direct contact with the graphene, and the metal substrate of the carrier is exposed to the atmosphere with its surface facing upwards.

[0049] Step 5: Etching: Place the graphene foil carrying the grid from Step 4 onto the surface of the etching solution. The etching solution includes an etchant, which can be sodium persulfate, ferric chloride, or sodium ammonium persulfate. The concentration of the etchant in the etching solution is 1 mol / L, and the etching time is 4 hours. The metal substrate of the floating graphene foil is etched to obtain the grid / graphene combination. Floating etching achieves efficient removal of the metal substrate while ensuring that the graphene on the front side is not contaminated, thus completing the transfer of graphene from the metal substrate to the grid substrate. Please refer to the appendix. Figure 4 After the metal substrate is etched, the graphene film carrying the grid floats on the surface of the etching solution.

[0050] Step Six: Cleaning and Drying. The graphene carrier was transferred again: The carrier obtained in Step Five was transferred to deionized water for cleaning. The resistivity of deionized water is 18.25 MΩ·cm. The cleaning was repeated 3 times, with each cleaning lasting 50 min.

[0051] The graphene electron microscope (EM) mesh was then dried to obtain a re-transferred graphene EEM mesh. Natural drying yielded a re-transferred graphene EEM mesh with a graphene coverage of up to 98%. Please refer to the appendix. Figure 5 - Appendix Figure 6 SEM and AFM characterization images of graphene transferred after plasma treatment. Example 3

[0052] Please see the appendix Figure 1 A method for recycling and regenerating graphene electron microscopy (EM) web includes the following steps: Step 1: Screening for Recyclable Screening Materials: Using an optical microscope, unqualified screening materials that meet recycling standards are screened. The recycling standards for unqualified screening materials are: visually inspected surface flatness; under the optical microscope, the number of damaged carbon film squares does not exceed 2% of the total number of squares; and the location of the carbon film damage is not within a circle with a diameter of 1.5 mm centered on the screen's center. By comparing against the recycling standards, unqualified screening materials are screened out for recycling, achieving the recycling and reuse of screening materials. Please refer to the appendix. Figure 2 Optical microscope images: the left side shows a screen that meets the recycling standards, and the right side shows a screen that does not meet the recycling standards.

[0053] Step Two: Cleaning and Soaking the Textile: The defective textile from Step One will be cleaned using plasma cleaning; please refer to the appendix. Figure 3 A comparison of the plasma-treated grid before and after treatment: the left image shows the state before treatment, and the right image shows the state after treatment.

[0054] The mesh is placed on a clean glass slide. The mesh can be a microgrid made of gold (Au), copper (Cu), or nickel (Ni) mesh. The porous membrane side of the mesh is in direct contact with the glass slide. The porous membrane is a porous nickel-titanium membrane. The metal substrate side of the mesh is exposed.

[0055] A glass slide carrying a graphite grid is placed in a plasma cleaner and cleaned under the set parameters: air flow rate of 15 sccm, power of 50 W, and processing time of 60 s. This removes the low-coverage graphene layer within the suspended holes of the graphite grid. Plasma cleaning efficiently removes residual graphene from the grid holes for secondary transfer.

[0056] After cleaning, the substrate is immersed in an organic solvent to obtain a clean substrate. The plasma-cleaned substrate is then unloaded from the glass slide and immersed in an organic solvent, specifically isopropanol, acetone, or ethanol, for 6 hours. Acetone dissolves photoresist and polymer residues, while ethanol or isopropanol dissolves moisture and small organic molecule impurities without reacting with the graphene itself, allowing them to be removed by evaporation after cleaning. This provides further cleaning of the substrate surface.

[0057] Step 3: Pretreatment of foil graphene: The foil graphene is subjected to plasma treatment to remove the graphene on the back side, resulting in foil graphene that retains the graphene on the front side. The foil graphene includes a metal substrate and a graphene film grown on the metal substrate by chemical vapor deposition (CVD). The metal substrate may be made of copper, nickel, molybdenum or copper-nickel alloy and has a thickness of 20 μm. The graphene film is a single-layer monocrystalline graphene layer with a large domain region, a double-layer graphene layer, or a triple-layer graphene layer.

[0058] Step 4: Placement: Place the carrier obtained in Step 2 on the front side of the foil graphene obtained in Step 3 to form a combination of carrier / graphene / foil metal substrate; the carrier is placed in an array on the foil graphene, the porous membrane is in direct contact with the graphene, and the metal substrate of the carrier is exposed to the atmosphere with its surface facing upwards.

[0059] Step 5: Etching: Place the graphene foil carrying the grid from Step 4 onto the surface of the etching solution. The etching solution includes an etchant, which can be sodium persulfate, ferric chloride, or sodium ammonium persulfate. The concentration of the etchant in the etching solution is 0.08 mol / L, and the etching time is 3 h. The metal substrate of the floating graphene foil is etched to obtain the grid / graphene combination. Floating etching achieves efficient removal of the metal substrate while ensuring that the graphene on the front side is not contaminated, thus completing the transfer of graphene from the metal substrate to the grid substrate. Please refer to the appendix. Figure 4 After the metal substrate is etched, the graphene film carrying the grid floats on the surface of the etching solution.

[0060] Step Six: Cleaning and Drying. The graphene carrier was transferred again: The carrier obtained in Step Five was transferred to deionized water for cleaning. The resistivity of deionized water is 18.25 MΩ·cm. The cleaning was performed twice, with each cleaning lasting 40 min.

[0061] The graphene electron microscope (EM) mesh was then dried to obtain a re-transferred graphene EEM mesh. Natural drying yielded a re-transferred graphene EEM mesh with a graphene coverage of up to 98%. Please refer to the appendix. Figure 5 - Appendix Figure 6 SEM and AFM characterization images of graphene transferred after plasma treatment. Example 4

[0062] Unlike the embodiments described above, plasma treatment was not used; instead, the graphene was directly re-transferred after soaking the substrate in an organic solvent. After re-transfer, severe interlayer contamination of the graphene occurred; please refer to the appendix. Figure 7 - Appendix Figure 8 SEM and AFM characterization images of graphene transferred after plasma treatment.

[0063] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for recycling and regenerating graphene electron microscope (TEM) support mesh, characterized in that: Includes the following steps: Step 1: Screening for recyclable screens: Use an optical microscope to screen for non-conforming screens that do not meet recycling standards; Step 2: Cleaning and soaking the carrier: The defective carrier from Step 1 is first cleaned by plasma, and after cleaning, it is soaked in an organic solvent to obtain a clean carrier. Step 3: Pretreatment of foil graphene: The foil graphene is subjected to plasma treatment to remove the graphene on the back side, resulting in foil graphene that retains the graphene on the front side. Step 4: Placement: Place the carrier obtained in Step 2 on the front side of the foil graphene obtained in Step 3 to form a combination of carrier / graphene / foil metal substrate. Step 5: Etching: Place the foil graphene carrying the carrier in step four on the surface of the etching solution, and float the metal substrate of the foil graphene to obtain the carrier / graphene combination. Step Six: Cleaning, Drying, and Re-transferring the Graphene Grid: The grid obtained in Step Five was transferred to deionized water for cleaning and then dried to obtain a re-transferred graphene electron microscopy grid.

2. The method for recycling and regenerating graphene electron microscope support according to claim 1, characterized in that: In step 1, the recycling standard for unqualified carrier nets is that the surface of the carrier net is flat by visual inspection, the number of damaged carbon film squares under a light microscope does not exceed 2% of the total number of squares, and the location of the carbon film damage is not within a circle with the center as the center and a diameter of 1.5 mm.

3. The method for recycling and regenerating graphene electron microscope support according to claim 2, characterized in that: In step two, the mesh is placed on a clean glass slide, with the porous membrane side of the mesh in direct contact with the glass slide and the metal substrate side of the mesh exposed. The glass slide carrying the mesh is then placed in a plasma cleaner and cleaned under set parameters, namely, adjusting the air flow rate to 5 sccm to 30 sccm, the power to 20 W to 100 W, and the processing time to 10 s to 150 s, to remove the low-coverage graphene layer in the suspended pores of the mesh.

4. The method for recycling and regenerating graphene electron microscope support according to claim 3, characterized in that: In step two, the plasma-cleaned screen is unloaded from the glass slide, and then the screen is immersed in an organic solvent for 1 to 10 hours. The organic solvent is specifically isopropanol, acetone, or ethanol.

5. The method for recycling and regenerating graphene electron microscope support according to claim 4, characterized in that: In step three, the foil graphene includes a metal substrate and a graphene film grown on the metal substrate by chemical vapor deposition (CVD). The metal substrate can be copper, nickel, molybdenum or copper-nickel alloy, and the thickness of the metal substrate is 10μm to 50μm. Graphene films can be single-layer monocrystalline graphene layers with large domain regions, double-layer graphene layers, or 2-5 layers of graphene.

6. The method for recycling and regenerating graphene electron microscope grids according to claim 3, characterized in that: The carrier mesh can be a microgrid made of gold mesh (Au), copper mesh (Cu), or nickel mesh (Ni), and the porous membrane can be a porous carbon membrane or a porous nickel-titanium membrane.

7. The method for recycling and regenerating graphene electron microscope grids according to claim 3, characterized in that: In step four, the carrier mesh is arranged in an array on the foil graphene, with the porous membrane in direct contact with the graphene and the metal substrate of the carrier mesh facing upwards and exposed to the atmosphere.

8. The method for recycling and regenerating graphene electron microscope support according to claim 5, characterized in that: In step five, the etching solution includes an etchant, which is sodium persulfate, ferric chloride, or sodium ammonium persulfate. The concentration of the etchant in the etching solution is 0.05–1 mol / L, and the etching time is 0.5–5 h.

9. The method for recycling and regenerating graphene electron microscope support according to claim 1, characterized in that: In step six, the resistivity of the deionized water is 18.25 MΩ·cm, and the washing is performed 3 to 4 times, with each washing session lasting 10 to 60 minutes.

10. The method for recycling and regenerating graphene electron microscope support according to claim 1, characterized in that: In step six, the graphene electron microscope screen is naturally dried to obtain a re-transferred graphene screen with a graphene coverage of up to 97% to 98%.

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