Method for preparing transmission electron microscope grid covered by single-layer graphene oxide
A transmission electron microscope (TEM) mesh covered with monolayer graphene oxide was prepared by steps such as centrifugation filtration, drying, and wet transfer. This solved the problems of graphene oxide aggregation and multilayer stacking in the existing technology, and achieved high-resolution and accurate TEM mesh preparation, thus promoting the development of nanotechnology and biomedical imaging.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-27
- Publication Date
- 2026-03-27
AI Technical Summary
Existing methods for preparing transmission electron microscope grids covered with graphene oxide are complex and prone to problems such as graphene oxide aggregation, multilayer stacking, and wrinkles.
A transmission electron microscope (TEM) mesh covered with monolayer graphene oxide was prepared by a method involving centrifugal filtration, drying, wet transfer, and vapor solvent treatment. The process included dispersing, drying, transferring graphene oxide powder to a substrate, and removing residual composites.
High-quality, single-layer-covered transmission electron microscope grids were fabricated, improving resolution and accuracy, simplifying the operation process, and making them suitable for nanotechnology, materials science, and biomedical imaging.
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Figure CN121740567A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a method for preparing a transmission electron microscope (TEM) grid, and more precisely, to the preparation of a TEM grid covered by a single layer of graphene oxide (GO). BACKGROUND
[0002] Graphene oxide (GO) is a promising carbon-based material, whose layered structure is composed of graphene oxide sheets, known as GO sheets. These sheets have a special structure, with both basal planes and edges rich in oxygen functional groups such as hydroxyl, epoxy, and carboxyl groups. GO membranes, as a self-supporting carbon-based membrane material, are formed by the assembly of individual GO sheets, not only showing excellent mechanical properties, but also having excellent structural stability. Its unique macroscopic flexibility and rigidity are derived from the unique staggered tile arrangement of nanoscale GO sheets, making GO have a wide application prospect in many fields.
[0003] In recent years, GO has received extensive attention due to its unique structure and chemical properties, and has shown extensive application potential in many fields. As a derivative of graphene, GO presents a special two-dimensional structure in which carbon atoms are connected together in a hexagonal arrangement, while the surface is scattered with oxygen-rich functional groups. These functional groups endow GO with unique chemical properties such as hydrophilicity, dispersibility, and tunable electronic properties, making it have a wide range of applications in the fields of materials science, biomedicine, and electronics.
[0004] In the field of transmission electron microscopy (TEM), GO is an important support material that can be used for imaging nanoscale structures and materials. Using GO support films in TEM imaging has multiple advantages such as enhanced contrast, improved stability, and compatibility with biological samples. In addition, by controlling the thickness and composition of the GO film, the TEM imaging conditions can be fine-tuned to achieve high-resolution characterization of different samples. GO not only serves as a support material in TEM applications, but also can be used for ion adsorption and analysis. GO has abundant surface functional groups such as carboxyl and hydroxyl groups, making it have good ion adsorption performance. In the fields of ion sensors, pollutant removal, biomedical and electrochemical sensors, GO is widely used for adsorption and detection of heavy metal ions, organic matter and biomolecules in water. In TEM applications, by observing the interaction between GO and the ions to be measured, the adsorption behavior and morphological characteristics of the ions on the GO surface can be directly observed. Using TEM technology, the microstructure and adsorption mechanism of GO ion adsorption materials can be directly observed and characterized, providing important reference for their optimization and improvement in various ion adsorption applications.
[0005] However, existing methods for preparing GO-coated TEM meshes are relatively complex. Furthermore, common challenges associated with traditional preparation techniques include GO agglomeration, multilayer stacking, and wrinkle formation. One embodiment of this invention aims to address the shortcomings of existing technologies by providing a simple and rapid method for producing single-layer GO-coated TEM meshes. Summary of the Invention
[0006] According to a first aspect of the present invention, a method for preparing a transmission electron microscope grid covered by a single layer of graphene oxide is provided, comprising the following steps: (i) dispersing graphene oxide powder in an aqueous solution and centrifuging and filtering to obtain a graphene oxide dispersion; (ii) placing the graphene oxide dispersion on a substrate surface and drying it to form a graphene oxide dispersion layer; (iii) transferring the graphene oxide dispersion layer on the substrate surface to the surface of a composite using a wet transfer method; (iv) transferring the composite with the graphene oxide dispersion layer onto the transmission electron microscope grid, drying it in a dry environment, and removing any residual composite.
[0007] Preferably, the graphite oxide powder is made of a single layer of graphite oxide with a total weight of 1 mg, and the width of each of the graphite oxide powders is 10-50 μm.
[0008] Preferably, the aqueous solution is ultrapure water with a volume of 20 ml.
[0009] Preferably, the dispersion of the graphite oxide powder is carried out by ultrasonic dispersion, wherein the ultrasonic dispersion is performed using a probe ultrasonic instrument with a power of 600W, an ultrasonic time of 1 second, a pause time of 1 second, and a total time of 1 hour.
[0010] Preferably, the centrifugal filtration of the graphite oxide powder is carried out at a centrifugal speed of 2000 revolutions per minute for 10 minutes.
[0011] Preferably, the substrate is a fluorophlogopite substrate with a size of 1 square centimeter.
[0012] Preferably, the composite is a polymethyl methacrylate (PMMA) solution, wherein the wet transfer method employs a spin coater to coat the PMMA solution onto the substrate surface, and the substrate coated with the PMMA solution is placed in a water bath at 75°C to promote the separation of the PMMA from the substrate.
[0013] Preferably, the spin coater operates at a first spin coating speed and a second spin coating speed, wherein the first spin coating speed is 800 rpm for 10 seconds and the second spin coating speed is 3000 rpm for 1 minute.
[0014] Preferably, the temperature of the drying environment is 25°C and the humidity is 50% to 80%.
[0015] Preferably, the step of removing residual complexes uses a vapor solvent, wherein the vapor solvent includes acetone vapor at a temperature of 75°C.
[0016] Preferably, the present invention also provides a method for preparing a monolayer GO-coated TEM support grid: 1) Obtaining a monolayer GO dispersion: GO is dispersed in water, ultrasonically dispersed for 1 hour, and then centrifuged and filtered to obtain a graphene oxide dispersion; 2) Preparing a monolayer GO dispersion layer: The GO dispersion obtained in step 1) is titrated onto a fluorophlogopite substrate and dried; 3) Separating the GO layer from the mica substrate: The monolayer GO obtained in step 2 on the surface of the fluorophlogopite substrate is transferred to the PMMA surface using a wet transfer method; 4) Preparing a GO-coated TEM support grid: The GO obtained in step 3 is separated into three layers and transferred to the surface of the monolayer GO sheet formed on the TEM grid, dried, and the residual composite is removed.
[0017] The method of this invention effectively avoids common problems in traditional preparation methods, such as graphene oxide agglomeration, multilayer stacking, and wrinkling. Using this technique, the resulting transmission electron microscope (TEM) mesh covered with graphene oxide can serve as excellent support for single-atom TEM measurements, thereby improving resolution and accuracy.
[0018] Furthermore, the fabrication process outlined in this invention is simple and easy to operate, making it usable even by researchers with limited expertise in TEM grid fabrication techniques. This ensures wider adoption and application of this method in various research fields crucial to TEM analysis. The disclosed method provides a reliable and efficient approach for utilizing GO in TEM grid fabrication, which is of great significance for advancing research in nanotechnology, materials science, and biomedical imaging. This method enables the fabrication of high-quality, monolayer-covered GO TEM grids, opening new avenues for exploring the nanoworld with unprecedented clarity and precision. Attached Figure Description
[0019] This invention will be described with reference to the accompanying drawings, which are as follows:
[0020] Figure 1 This is a schematic diagram illustrating one embodiment of a method for preparing a transmission electron microscope (GO-TEM) grid covered by a single layer of graphene oxide according to the present invention;
[0021] Figure 2 This is a magnified image of the morphology of a single layer of graphene oxide sheet on a fluorophlogopite substrate.
[0022] Figure 3This is a scanning transmission electron microscope (STEM) image showing a magnified portion of a GO-TEM grid formed according to an embodiment of the method of the present invention;
[0023] Figure 4a It is an atomic-scale STEM image of four potassium ions on a single layer of graphene oxide; and
[0024] Figure 4b yes Figure 4a Atomic structure diagram of potassium ions. Detailed Implementation
[0025] Transmission electron microscopy (GO-TEM) grids covered by a single layer of graphene oxide provide a versatile platform for a wide range of applications in nanotechnology, materials science, biology, catalysis, and other fields where TEM imaging and analysis are crucial for understanding the structure and behavior of nanoscale systems. For example, with advancements in TEM technology, researchers are now able to visualize individual atoms using aberration-corrected TEMs. The GO-TEM monolayer grid provides an ideal substrate for imaging single atoms, enabling the study of atomic-scale phenomena in materials science and chemistry.
[0026] refer to Figure 1 This relates to one embodiment of a method 100 for preparing a TEM grid coated with graphene oxide (GO). The method 100 includes the following steps: First, dispersing graphene oxide powder in an aqueous solution and centrifuging and filtering to obtain a graphene oxide dispersion 110. Approximately 95% of the graphene oxide powder consists of monolayer graphene oxide with a size of 10-50 μm, and the total weight of the graphene oxide powder is 1 mg. In one embodiment, the aqueous solution is ultrapure water and is generated by a Mili-Q water supply system. The required volume of ultrapure water is approximately 20 mL. In one embodiment, the dispersion of the graphene oxide powder is performed using a probe sonicator at a power of 600 W, with a sonication time of 1 second, a pause time of 1 second, and a total time of 1 hour.
[0027] After obtaining the graphene oxide dispersion 110, the dispersion 110 is dropped onto the surface of the substrate 120 and dried in an environment with a temperature of 25°C and a humidity of 50% to 80%, forming a monolayer graphene oxide dispersion layer on the substrate 120. In one embodiment, the substrate is made of fluorophlogopite and has a size of 1 square centimeter. Then, the monolayer graphene oxide dispersion layer 110 on the substrate 120 is transferred to the surface of the composite 130 using a wet transfer method. The composite 130 may be polymethyl methacrylate (PMMA). This wet transfer process uses a spin coater to coat the mica substrate surface with 15 μL of PMMA solution in two coats: the first coat is applied at 800 rpm for 10 seconds, and the second coat is applied at 3000 rpm for 1 minute. Subsequently, the substrate coated with the PMMA solution is placed in a water bath at 75°C to promote the separation of the PMMA from the substrate.
[0028] Finally, the composite 130 with the monolayer graphene oxide dispersion layer is transferred onto a transmission electron microscope (TEM) grid 140 and dried in a dry environment. The drying environment is at a temperature of 25°C and a humidity of 50% to 80%. After completion, any remaining composite is removed with a vapor solvent (such as acetone vapor) at a temperature of approximately 75°C, thus producing a TEM grid covered with monolayer graphene oxide 150.
[0029] Example 1
[0030] A small amount (2 mg) of GO powder was dispersed in ultrapure water using probe sonication for 1 hour or bath sonication for 5 hours to produce individual monolayer GO flakes. The resulting GO dispersion was then centrifuged at 3000 rpm to remove thicker GO samples. A drop of the supernatant was then applied to a fluorophlogopite substrate to form a uniform monolayer GO film on the mica substrate. Figure 2 A magnified image showing the morphology of a single-layer GO sheet on a fluorinated phlogopite substrate is displayed.
[0031] After the GO layer was dried at room temperature, PMMA was uniformly coated onto the GO layer using a spin-coating method. The mica substrate coated with PMMA was then placed in a 75°C water bath to promote the separation of PMMA from mica, leaving a GO layer on the PMMA surface. The obtained PMMA was then spread evenly onto a TEM grid and dried at room temperature to remove internal moisture. Finally, acetone vapor was used to remove the PMMA, leaving a GO layer on the TEM grid. Figure 3 This is a scanning transmission electron microscope (STEM) image showing a TEM grid covered with a single layer of GO prepared in Example 1.
[0032] Example 2
[0033] This example will carefully illustrate the TEM study supporting individual atoms on the GO layer. A small amount (2 mg) of GO powder was dispersed in ultrapure water using probe sonication for 1 hour or bath sonication for 5 hours to produce individual monolayer GO flakes. The resulting GO dispersion was then centrifuged at 3000 rpm to remove thicker GO samples. A drop of the supernatant was then applied to a fluorophlogopite substrate to form a uniform monolayer GO film on the mica substrate. After drying the GO layer at room temperature, PMMA was uniformly coated onto the GO layer using a spin-coating method. The PMMA-coated mica substrate was placed in a 75°C water bath to promote the separation of PMMA from the mica, leaving the GO layer on the PMMA surface. The resulting PMMA-GO layer was then placed in a salt solution (2000 ppm K). + The PMMA-GO layer was then laid in the TEM grid for half an hour and dried at room temperature. The PMMA-GO was then spread evenly onto the TEM grid and dried at room temperature to remove internal moisture. Finally, acetone vapor was used to remove the PMMA, leaving a GO layer on the TEM grid. Figure 4a This shows an atomic-scale STEM image of four potassium ions (K) on a monolayer GO layer. Figure 4b This shows the atomic structure corresponding to the potassium ion K.
[0034] Compared to traditional TEM grids, GO-TEM grids exhibit higher stability (30-50 seconds, dose of 50). It offers several advantages: lower background noise (only 50% lower than amorphous carbon film TEM meshes), and higher contrast and resolution (up to 50 pm). The GO-TEM mesh has a uniform surface coverage, is functionally compatible, and simplifies sample preparation and transfer. Its biocompatibility makes it suitable for imaging biological samples. Examples of this invention ensure a GO monolayer ratio exceeding 80% and a mesh coverage exceeding 60%. This method is simple, does not involve any toxic or harmful chemicals, and avoids the drawbacks of graphene oxide aggregation, multilayer stacking, and wrinkling. The preparation process is simple and easy to operate, enabling the graphene oxide-covered transmission electron microscope mesh to support single-atom transmission electron microscopy measurements.
Claims
1. A method for preparing a transmission electron microscope grid covered with a single layer of graphene oxide, characterized in that, Includes the following steps: (i) Disperse graphene oxide powder in an aqueous solution and centrifuge and filter to obtain a graphene oxide dispersion; (ii) The graphene oxide dispersion is placed on the substrate surface and dried to form a graphene oxide dispersion layer. (iii) The graphene oxide dispersion layer on the substrate surface is transferred to the surface of the composite using a wet transfer method; (iv) The composite with the graphene oxide dispersion layer is transferred onto the transmission electron microscope grid, dried in a dry environment, and residual composite is removed.
2. The method according to claim 1, characterized in that, The graphite oxide powder is made of a single layer of graphite oxide with a total weight of 1 milligram, and each of the graphite oxide powders has a width of 10-50 μm.
3. The method according to claim 1, characterized in that, The aqueous solution is ultrapure water with a volume of 20 ml.
4. The method according to claim 1, characterized in that, The dispersion of the graphite oxide powder is carried out by ultrasonic dispersion, wherein the ultrasonic dispersion is performed using a probe ultrasonic instrument with a power of 600W, an ultrasonic time of 1 second, a pause time of 1 second, and a total time of 1 hour.
5. The method according to claim 1, characterized in that, The centrifugal filtration of the graphite oxide powder is carried out at a centrifugal speed of 2000 revolutions per minute for 10 minutes.
6. The method according to claim 1, characterized in that, The substrate is a fluorophlogopite substrate with a size of 1 square centimeter.
7. The method according to claim 1, characterized in that, The composite is a polymethyl methacrylate (PMMA) solution. The wet transfer method uses a spin coater to coat the PMMA solution onto the substrate surface and places the substrate coated with the PMMA solution into a water bath at 75°C to promote the separation of the PMMA from the substrate.
8. The method according to claim 7, characterized in that, The spin coater operates at a first spin coating speed and a second spin coating speed, wherein the first spin coating speed is 800 rpm for 10 seconds and the second spin coating speed is 3000 rpm for 1 minute.
9. The method according to claim 1, characterized in that, The temperature of the drying environment is 25°C, and the humidity is 50% to 80%.
10. The method according to claim 1, characterized in that, The step of removing the residual complex uses a vapor solvent, which includes acetone vapor at a temperature of 75°C.