TWI417934B - Method for making transmission electron microscope grid - Google Patents

Description

Method for preparing TEM micro-gate

The invention relates to a preparation method of a transmission electron microscope microgrid.

In transmission electron microscopy, an amorphous carbon support film (microgrid) is an important tool for carrying powder samples for high-resolution image observation (HRTEM) observation by transmission electron microscopy. With the continuous development of nanomaterial research, microgrids are increasingly used in the field of electron microscopy characterization of nanomaterials. In the prior art, the microgrid applied to a transmission electron microscope is usually formed by covering a metal mesh such as a copper mesh or a nickel mesh with a porous organic film and then vapor-depositing an amorphous carbon film. However, in practical applications, especially when observing the high-resolution image of the transmission electron microscope of the nanometer-sized particles, the amorphous carbon film in the micro-gate is thicker and the contrast noise is large, which is disadvantageous for the transmission electron microscope of the nano-particles. Increased imaging resolution.

Zhang Lina et al. developed a new type of TEM micro-gate (see Chinese Patent Application No. 200710073768.1), laying the carbon nanotube film on the surface of the metal grid, and the nano-sized particles to be observed are adsorbed on the carbon nanotubes. On the wall of the tube, the effect of the amorphous carbon film on the resolution of the TEM image is avoided. However, such a TEM microgrid does not have a high carrying capacity of the sample particles, and the observation is concentrated on a single sample particle, and it is not easy to simultaneously observe the distribution state of a large number of sample particles on a plane. In addition, When the sample particles are slightly larger, there is a possibility that the adsorption is not strong enough to fall off the tube wall of the carbon nanotube.

In view of the above, a method for preparing a transmission electron micro-gate is provided. The TEM micro-grid prepared by the method is more likely to obtain a high-resolution image of a transmission electron microscope when the nano-sized particles are used as an observation sample, and has a higher resolution. The sample carrying rate and sample support performance are suitable for simultaneous observation of a large number of nano-sized sample particles.

A method for preparing a transmission electron microstrip, comprising the steps of: providing a self-supporting carbon nanotube film structure, and a functionalized graphene sheet dispersion comprising a plurality of micropores; The functionalized graphene sheet dispersion infiltrates the surface of the carbon nanotube film structure; drying the carbon nanotube film structure infiltrated by the functionalized graphene sheet, thereby making the functionalized graphene sheet and the carbon nanotube The film structure is composited to form a graphene-nanocarbon tube composite film; and the through hole of the graphene-carbon nanotube composite film covering a support.

Compared with the prior art, the TEM micromirror preparation method obtains a carbon nanotube film structure by pulling from a carbon nanotube array, and the carbon nanotube film structure is used as a support skeleton with micropores. And further providing a functionalized graphene sheet to cover the support skeleton micropores. Since the functionalized graphene sheets have an extremely thin thickness, the contrast noise generated in the transmission electron microscope observation is small, and a TEM photograph with a higher resolution can be obtained. When used, nano-sized sample particles can be carried by functionalized graphene sheets, thereby improving sample carrying capacity and sample support performance, and are suitable for simultaneously observing a large number of nano-sized sample particles.

100‧‧‧ Transmission electron microscopy

110‧‧‧Support

112‧‧‧through hole

120‧‧‧graphene-nanocarbon tube composite film

122‧‧‧Nano Carbon Membrane Structure

124‧‧‧Functional graphene sheets

126‧‧‧Micropores

128‧‧‧Nano carbon pipeline

200‧‧‧ samples

Figure 1 is a schematic view showing the structure of a graphene oxide sheet.

2 is a schematic flow chart of a method for preparing a transmission electron microstrip micro-gate according to an embodiment of the present invention.

3 is a scanning electron micrograph of a carbon nanotube film in a TEM microgrid according to an embodiment of the present invention.

4 is a scanning electron micrograph of a structure of a carbon nanotube film formed by a plurality of intersecting carbon nanotube films in a transmission electron microscope micro-gate according to an embodiment of the present invention.

FIG. 5 is a transmission electron micrograph of a graphene oxide sheet-nanocarbon tube film structure in a transmission electron microscope micro-gate according to an embodiment of the present invention.

FIG. 6 is a schematic structural view of a transmission electron microscope micro-gate according to an embodiment of the present invention.

FIG. 7 is a structural schematic view showing a structure of a graphene oxide sheet-nanocarbon tube film in a transmission electron microscope micro-gate according to an embodiment of the present invention.

FIG. 8 is a schematic structural view showing another structure of a graphene oxide-nanocarbon tube film in a transmission electron microscope micro-gate according to an embodiment of the present invention.

FIG. 9 is a schematic view showing the structure of a transmission electron microscope micro-gate having a sample on the surface according to an embodiment of the present invention.

Fig. 10 is a transmission electron micrograph of a nano-particle for observation of a transmission electron microstrip micro-gate according to an embodiment of the present invention.

Figure 11 is a high-resolution transmission electron micrograph of the nano-particles observed in the TEM of the embodiment of the present invention.

The TEM micro-gate and the preparation method thereof provided by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

In the present invention, for convenience of description, a structure in which 1 to 10 layers of graphene are laminated on each other is referred to as a graphene sheet; and a structure in which 1 to 10 layers of graphene having a functional group are laminated on each other is referred to as a functionalized graphene sheet; A structure in which 1 to 10 layers of graphene having an oxidizing functional group are laminated on each other is referred to as a graphene oxide sheet. The graphene is composed of carbon atoms, and each carbon atom and the adjacent three carbon atoms are covalently bonded to each other and arranged in a hexagonal ring shape. At least one carbon atom of the graphene in the functionalized graphene sheet is linked to a chemical functional group through a covalent bond. The chemical functional group may be one or more of an oxygen-containing functional group, a nitrogen-containing functional group, a hydrocarbon group, a phosphorus-containing functional group, a sulfur-containing functional group, and a halogen-containing substituent. As shown in FIG. 1, at least one carbon atom in the graphene in the graphene oxide sheet is bonded to an oxygen-containing functional group through a covalent bond. The oxygen-containing functional group may be one or more of a carboxyl group, a carbonyl group, a hydroxyl group, an ester group, an aldehyde group, and an epoxy group. It can be understood that in the functionalized graphene sheet and the graphene oxide sheet, the graphene may have a plurality of carbon atoms connected to a plurality of the same or different functional groups.

Referring to FIG. 2, a first embodiment of the present invention is described by taking a graphene oxide sheet as an example. The preparation method of the TEM micro-gate mainly includes the following steps:

In the first step, a carbon nanotube film structure and a graphene oxide sheet dispersion are provided.

The carbon nanotube membrane structure includes a plurality of carbon nanotubes and micropores defined by the plurality of carbon nanotubes. The carbon nanotube film structure is a film-like structure formed on the surface of the support body for carrying the graphene sheet, so the specific structure of the carbon nanotube film structure is not limited. As long as there is a small through hole formed by a plurality of carbon nanotubes overlapping each other. Preferably, the carbon nanotube membrane structure is a self-supporting structure. More preferably, the carbon nanotube membrane structure comprises a plurality of layers of cross-laminated carbon nanotube membranes. The carbon nanotube film is obtained by directly drawing from a carbon nanotube array, and the preparation method comprises the following steps: First, providing a carbon nanotube array formed on a growth substrate, the array is super-aligned Nano carbon tube array.

The carbon nanotube array is prepared by chemical vapor deposition, and the carbon nanotube array is preferably a plurality of pure carbon nanotube arrays formed in parallel with each other and perpendicular to the growth substrate. Through the above controlled growth conditions, the aligned carbon nanotube array contains substantially no impurities, such as amorphous carbon or residual catalyst metal particles, and is suitable for drawing a carbon nanotube film therefrom. The carbon nanotube array provided by the embodiment of the invention is one of a single-walled carbon nanotube array, a double-walled carbon nanotube array, and a multi-walled carbon nanotube array. The carbon nanotubes have a diameter of 0.5 to 50 nm and a length of 50 nm to 5 mm. In this embodiment, the length of the carbon nanotubes is preferably from 100 micrometers to 900 micrometers.

Next, a carbon nanotube film is obtained by pulling a carbon nanotube from the carbon nanotube array using a stretching tool, which specifically includes the following steps: (a) from the super-shoring carbon nanotube array One of the plurality of carbon nanotubes having a certain width or a certain width is selected. In this embodiment, it is preferred to contact the carbon nanotube array with a tape, a tweezers or a clip having a certain width to select one or a plurality of carbon nanotubes having a certain width. (b) stretching the selected carbon nanotubes at a rate to form a plurality of carbon nanotube segments connected end to end, thereby forming a continuous carbon nanotube film. The pull direction is substantially perpendicular to the growth direction of the nanotube array.

During the above stretching process, the plurality of carbon nanotube segments are gradually separated from the growth substrate in the stretching direction under the tensile force, and the selected plurality of carbon nanotube segments are respectively combined with the other due to the van der Waals force. The carbon nanotube segments are continuously drawn end to end to form a continuous, uniform, self-supporting carbon nanotube film having a width. The self-supporting carbon nanotube film does not require a large-area support of the carrier, but can maintain its own membranous state as long as it provides supporting force on both sides, that is, the carbon nanotube film is placed (or fixed on) When the two supports are disposed at a certain distance, the carbon nanotube film located between the two supports can be suspended to maintain the self-membrane state. The self-supporting is mainly achieved by the presence of a continuous carbon nanotube in the carbon nanotube film which is continuously arranged by van der Waals force. Referring to FIG. 3, the carbon nanotube film comprises a plurality of carbon nanotubes arranged in a preferred orientation along the same direction. The preferred orientation means that the majority of the carbon nanotubes in the carbon nanotube film extend substantially in the same direction. Moreover, the overall direction of extension of the majority of the carbon nanotubes is substantially parallel to the surface of the carbon nanotube film. Further, most of the carbon nanotubes in the carbon nanotube membrane are connected end to end by van der Waals force. Specifically, each of the carbon nanotubes in the majority of the carbon nanotube membranes extending in the same direction and the carbon nanotubes adjacent in the extending direction are connected end to end by van der Waals force. Of course, there are a few randomly arranged carbon nanotubes in the carbon nanotube film, and these carbon nanotubes do not significantly affect the overall orientation of most of the carbon nanotubes in the carbon nanotube film. The method of directly stretching to obtain a carbon nanotube film is simple and rapid, and is suitable for industrial application.

The width of the carbon nanotube film is related to the size of the carbon nanotube array, and the length of the carbon nanotube film is not limited and can be obtained according to actual needs. When the area of the carbon nanotube array is At 4 inches, the width of the carbon nanotube film is 3 mm to 10 cm, and the thickness of the carbon nanotube film is 0.5 nm to 100 μm.

It can be understood that the preparation method of the carbon nanotube film structure may further include laminating and laminating a plurality of the carbon nanotube films. Specifically, one carbon nanotube film may be first covered on one frame in one direction, and another carbon nanotube film may be covered in the other direction to the surface of the previous carbon nanotube film, so that it is repeated several times. A plurality of carbon nanotube films are laid on the frame. The plurality of carbon nanotube films may be laid in different directions or may be laid only in two intersecting directions. It can be understood that the carbon nanotube membrane structure is also a self-supporting structure. The edge of the carbon nanotube membrane structure is fixed by the frame, and the middle portion is suspended.

Since the carbon nanotube film has a large specific surface area, the carbon nanotube film has a large viscosity, so the multilayer carbon nanotube film can be closely combined with each other by van der Waals force to form a stable carbon nanotube. Membrane structure. In the carbon nanotube membrane structure, the number of layers of the carbon nanotube membrane is not limited, and the adjacent two layers of carbon nanotube membranes have an intersection angle α, 0° < α ≦ 90 °. This embodiment is preferably α=90°, that is, the plurality of carbon nanotube films are stacked on each other only in two mutually perpendicular directions, and the number of layers of the carbon nanotube film in the carbon nanotube film structure is 2 to 4 layers. .

After forming the above-described carbon nanotube film structure, the carbon nanotube film structure may be further treated with an organic solvent to form a plurality of micropores in the carbon nanotube film structure.

The organic solvent is a volatile organic solvent at normal temperature, and one or a mixture of ethanol, methanol, acetone, dichloroethane and chloroform may be used. The organic solvent in this embodiment is ethanol. The organic solvent should have good wettability with the carbon nanotube. The step of treating with an organic solvent is specifically: infiltrating the entire surface of the carbon nanotube film structure formed on the frame by a test tube to infiltrate the entire carbon nanotube film structure, or the above-mentioned nano carbon can also be used. The tubular membrane structure is immersed in a container containing an organic solvent to infiltrate. Referring to the carbon nanotube membrane structure described in FIG. 4, after the organic solvent infiltration treatment, the side-by-side and adjacent carbon nanotubes are gathered to shrink into a spaced-apart nanocarbon pipeline, and the nanocarbon pipeline includes plural A carbon nanotube connected end to end by Van der Valli. There is a gap between the nanocarbon lines arranged substantially in the same direction. Since the carbon nanotubes in the adjacent two layers of carbon nanotube membranes have a crossing angle α and 0<α≦90°, the nanocarbon pipelines in the adjacent two layers of carbon nanotube membranes after the organic solvent treatment are mutually Crossing to form a plurality of micropores. After the organic solvent treatment, the viscosity of the carbon nanotube film is lowered. The size of the micropores of the carbon nanotube membrane structure is from 1 nm to 10 μm, preferably from 1 nm to 900 nm. In this embodiment, the intersection angle α=90°, so that the nanocarbon pipelines in the carbon nanotube membrane structure substantially cross each other perpendicularly to form a large number of micropores. Preferably, when the carbon nanotube structure comprises four stacked carbon nanotube membranes, the micropores having a size of nanometers in the nanocarbon membrane membrane structure can reach more than 60%. It can be understood that the larger the number of the laminated carbon nanotube film, the smaller the size of the micropores of the carbon nanotube film structure. Therefore, the desired pore size can be obtained by adjusting the number of the carbon nanotube membranes. The size of the micropores should be smaller than the size of the graphene oxide sheet so that the graphene oxide sheet can completely cover the micropores.

Further, the carbon nanotube membrane structure may be covalently functionalized such that one or more carbon atoms in the carbon nanotubes are linked to the chemical functional group by a covalent bond. Specifically, the carbon nanotube film obtained by pulling the carbon nanotube array can be placed in a functionalized solution, immersed for a period of time, and then taken out, and washed with deionized water. The carbon atoms of the carbon nanotubes in the carbon nanotube film are connected to other functional groups by a covalent bond. The functionalized solution may be a potassium permanganate solution, a sulfuric acid or a nitric acid solution or the like. The chemically functional carbon nanotube membrane structure and the functionalized graphene sheet can be joined by a bond between the functional groups of each other.

The graphene oxide sheet dispersion is obtained by dispersing a graphene oxide sheet in a solvent. In this embodiment, the method for preparing the graphene oxide sheet dispersion comprises: providing a certain amount of graphene oxide sheet; placing the graphene oxide sheet into a solvent to form a mixture; ultrasonically oscillating the mixture to form graphite oxide The olefin sheet is uniformly dispersed and suspended in the solvent to obtain a graphene oxide sheet dispersion. In this example, the mixture was shaken in an ultrasonic oscillator for about 15 minutes. It will be appreciated that other methods of dispersing the graphene oxide sheet may be employed, such as by stirring a mixture of the graphene oxide sheet and the solvent by mechanical agitation.

The solvent should be selected as a low molecular weight solvent which is advantageous for the dispersion of the graphene oxide sheet and which is completely volatile, such as a mixture of one or more of water, ethanol, methanol, acetone, dichloroethane and chloroform. In this embodiment, the solvent is water. It can be understood that the solvent only functions to uniformly disperse the graphene oxide sheet, so the solvent should not chemically react with the graphene oxide sheet.

The number of layers of graphene in the graphene oxide sheet is preferably from 1 to 3 layers, so that the transmission electron micro-gate has a better contrast. The molar ratio of carbon atoms to oxygen atoms in the graphene oxide sheet is preferably from 2:1 to 3:1. The graphene oxide sheet has a size of less than 100 microns, preferably less than 50 microns, and may be less than 1 micron. The graphene oxide sheet has a concentration of 5% (volume percentage) or less in the sample dispersion to be tested. The plurality of carbon atoms in the graphene in the graphene oxide sheet are connected to a plurality of oxygen-containing functional groups through a covalent bond.

In step two, the graphene oxide sheet dispersion is impregnated onto the surface of the carbon nanotube membrane structure.

The graphene oxide sheet dispersion can be dropwise added to the surface of the above-mentioned carbon nanotube film structure through a dropper so that the surface of the carbon nanotube film structure is wetted by the graphene oxide sheet dispersion. It can be understood that when the structure area of the carbon nanotube film is large, the carbon nanotube film can be immersed in the entire dispersion of the graphene oxide film by other means, such as the entire carbon nanotube film structure. The structure was taken out from the graphene oxide sheet dispersion. After infiltration, the graphene oxide sheet in the graphene sheet dispersion is distributed on the surface of the carbon nanotube film structure, and the graphene oxide sheet can further cover the micro-hole due to the presence of a large number of micropores in the carbon nanotube film structure. hole.

In this embodiment, a carbon nanotube film impregnated with the graphene oxide sheet dispersion is formed on the frame by dropping a graphene oxide sheet dispersion onto the surface of the carbon nanotube film structure laid on the frame. structure.

It can be understood that when the solvent in the dispersion of the graphene oxide sheet is a volatile organic solvent, the structure of the carbon nanotube membrane can be directly infiltrated through the dispersion to achieve the structure of infiltrating the carbon nanotube membrane with the organic solvent alone. The same effect.

After infiltrating the carbon nanotube film structure by the graphene oxide sheet dispersion, another nano carbon tube film structure may be further covered on the surface of the carbon nanotube film structure infiltrated by the graphene oxide sheet dispersion to form a Sandwich structure. It will be appreciated that the other carbon nanotube membrane structure may comprise a single or multiple layer of carbon nanotube membranes, which may have the same or different structure as the original carbon nanotube membrane structure. The step and the second step may be repeated, that is, after the sandwich structure is formed, the graphene oxide sheet dispersion droplet is further added to the sandwich junction. The surface is structured and further covers another carbon nanotube film structure to form a multilayer sandwich structure. This step is an optional step. Further, a plurality of carbon nanotube film structures which have been infiltrated by the graphene oxide sheet dispersion may be laminated to obtain the multilayer sandwich structure.

In the third step, the structure of the carbon nanotube film infiltrated by the graphene oxide sheet is dried, so that the graphene oxide sheet and the carbon nanotube film structure are combined to form a graphene-nanocarbon tube composite film.

After the graphene oxide sheet dispersion is dried, a graphene oxide sheet layer is formed on the surface of the carbon nanotube film structure. The graphene oxide sheet in the graphene oxide sheet layer may be continuously or discretely distributed on the surface of the carbon nanotube film structure, depending on the number and concentration of the graphene oxide sheet dispersion. Referring to FIG. 5, in the graphene-carbon nanotube composite film, at least one graphene oxide sheet covers at least one micropore in the carbon nanotube film structure. Preferably, the plurality of graphene oxide sheets uniformly cover the plurality of micropores in the carbon nanotube membrane structure.

The multilayer sandwich structure comprises a multilayered carbon nanotube film structure laminated with a plurality of layers of graphene oxide sheets. In this embodiment, the sandwich structure is a three-layer sandwich structure formed by a two-layer carbon nanotube film structure and a layer of graphene oxide sheets. In the multi-layer sandwich structure, the carbon nanotubes in the adjacent two layers of carbon nanotube film structure sandwich the graphene oxide sheet in the graphene oxide sheet layer, so that the graphene oxide sheet is more stably fixed in the layer. Three-layer sandwich structure.

After drying, the graphene oxide sheet is adsorbed to the surface of the carbon nanotube film structure by van der Waals force. In order to make the bonding stronger, the graphene-nanocarbon tube composite is formed After the film, the graphene-carbon nanotube composite film may be further processed to bond the graphene oxide sheet to the carbon nanotube in the carbon nanotube film.

The processing step may specifically be irradiating the graphene-nanocarbon tube composite film by laser or ultraviolet light; or bombarding the graphene-nanocarbon tube composite film by high-energy particles. After the treatment, the carbon atoms in the graphene oxide sheet and the carbon atoms in the carbon nanotubes are covalently bonded by sp3 hybridization, thereby making the graphene oxide sheet more stably fixed to the carbon nanotube membrane structure. surface. This step is an optional step, and when the method does not include the step, the graphene oxide sheet is bonded to the carbon nanotube by a van der Waals force.

In step four, the graphene-carbon nanotube composite film is covered with a support.

The support body has at least one through hole, and the graphene-carbon nanotube composite film covers a partially suspended arrangement of the through hole. The support may be a grid of metal mesh or other materials commonly used in a TEM microgrid. The support body in this embodiment is a disk-shaped metal mesh having a plurality of through holes.

When the area of the graphene-nanocarbon nanotube composite membrane is large, the method further includes: spacing a plurality of support bodies to be arranged; covering the plurality of support bodies by the graphene-carbon nanotube composite film; and The graphene-nanocarbon nanotube composite membrane is broken between the adjacent two supports, thereby forming a plurality of supports covered with a graphene-nanocarbon nanotube composite membrane at one time. Specifically, the laser beam can be used to focus and illuminate between two adjacent supports, and the graphene-carbon nanotube composite film is blown. In this embodiment, the laser beam power is 5 to 30 watts (W), preferably 18 watts.

Further, the graphene-nano coated on the support may be treated with an organic solvent The carbon tube composite film combines the graphene-nanocarbon tube composite film and the support body, and removes the excess graphene-nanocarbon tube composite film along the edge of the support, thereby forming a transmission electron microscope microgrid.

The above organic solvent is an organic solvent which is volatile at normal temperature, such as ethanol, methanol, acetone, dichloroethane or chloroform, and ethanol is used in this embodiment. The organic solvent can be directly dropped on the surface of the graphene-nanocarbon tube composite membrane, so that the graphene-nanocarbon tube composite membrane and the support are tightly combined. Further, the above-mentioned support covered with the graphene-carbon nanotube composite film may be entirely immersed in a container containing an organic solvent to be infiltrated. The step of removing the excess graphene-carbon nanotube composite film other than the support may be performed by focusing a laser beam and irradiating the edge of the support body for one week to ablate the graphene-nanocarbon tube composite film, thereby The excess graphene-nanocarbon tube composite membrane outside the support body is removed. This step is an optional step.

Further, after the third step or the fourth step, the graphene-carbon nanotube composite film may be subjected to a heat treatment step, which is performed under a vacuum or a shielding gas, and the heat treatment temperature is 100 ° C to 300 ° C, preferably It is 200 °C. The shielding gas may be selected from one or more of nitrogen and an inert gas. The conductivity of the graphene-nanocarbon tube composite film after heat treatment is improved, which is favorable for improving the resolution of the transmission electron microscope photograph.

When the carbon nanotube membrane structure comprises a functionalized carbon nanotube, the heating step can also react the functional group in the functionalized graphene sheet with the functional group in the carbon nanotube membrane structure to thereby functionalize the graphite. The carbon atoms in the olefin sheet and the carbon atoms in the carbon nanotube film structure are bonded to each other through a functional group. Specifically, the functional group in the functionalized graphene sheet can be designed to match the functional group in the carbon nanotube membrane structure, thereby A chemical reaction can occur.

The preparation method of the TEM micro-gate provided by the embodiment of the invention has the following advantages. First, since the carbon nanotube film and the carbon nanotube film structure formed by the carbon nanotube film are self-supporting, they can be conveniently laid and laminated, and in addition, a carbon nanotube film structure can be conveniently covered. On the other surface of the carbon nanotube film structure having a graphene oxide sheet, the two carbon nanotube film structure is sandwiched between the graphene oxide sheets. Secondly, the method of treating the graphene-nanocarbon tube composite film by using laser, ultraviolet light or high-energy particles can make the graphene oxide sheet and the carbon nanotube film be more firmly bonded by a covalent bond. Thirdly, when the carbon nanotube membrane structure is covalently functionalized, it can be more advantageously combined with the functionalized graphene sheet to make the combination of the two more stable. In addition, since the carbon nanotube film structure has a large specific surface area, it has a large viscosity and can adhere well to the support, and the carbon nanotube film structure and the support are treated by an organic solvent. The combination is stronger. Further, the graphene oxide-nanocarbon tube composite film can be covered on a plurality of supports at one time, and the method is simple and rapid, and the batch-prepared property can be prepared by removing the graphene-nanocarbon tube composite membrane other than the support. Stable TEM microgrid.

It can be understood that the graphene oxide sheet in the above method of the present invention can be replaced by other functionalized graphene sheets to form a graphene-carbon nanotube composite film containing other functionalized graphene sheets, and covering the surface of the support. .

Referring to FIG. 5, FIG. 6 and FIG. 7, the present invention provides a TEM micro-gate 100 comprising a support body 110 and a graphene-carbon nanotube composite film 120 covering the surface of the support body 110.

The graphene-carbon nanotube composite film 120 includes at least one carbon nanotube film structure 122 and a plurality of functionalized graphene sheets 124 disposed on the surface of the carbon nanotube film structure 122. The carbon nanotube membrane structure 122 includes a plurality of micropores 126 having a size that matches the size of the functionalized graphene sheet 124 such that at least one microwell 126 is covered by a functionalized graphene sheet 124. . Specifically, the functionalized graphene sheet may be a graphene oxide sheet. Preferably, a plurality of graphene oxide sheets uniformly cover a plurality of micropores 126 in the carbon nanotube membrane structure 122.

The carbon nanotube membrane structure 122 includes a plurality of carbon nanotubes that intersect each other to define a plurality of micropores 126. The carbon nanotubes in the carbon nanotube membrane structure 122 may be arranged in an orderly or ordered manner. When the carbon nanotubes are randomly arranged, the plurality of carbon nanotubes may be intertwined to form the carbon nanotube film structure 122. When the carbon nanotubes are arranged in an order, the plurality of carbon nanotubes may respectively extend in several certain directions and cross each other. It can be understood that the arrangement of the carbon nanotubes in the carbon nanotube film structure 122 is not limited, and only a plurality of carbon nanotubes are overlapped to form a minute through hole, and the function of supporting the micro through hole is supported. The graphene sheet 124 can be used. The carbon nanotube membrane structure 122 may further comprise one or more chemical functional groups linked to one or more carbon atoms in the carbon nanotube by covalent bonds. Similar to the functionalized graphene, the chemical functional group may be one or more of an oxygen-containing functional group, a nitrogen-containing functional group, a hydrocarbon group, a phosphorus-containing functional group, a sulfur-containing functional group, and a halogen-containing substituent.

Specifically, referring to FIG. 3 and FIG. 4 together, the carbon nanotube film structure 122 may include a plurality of layers of carbon nanotube film laminates. The carbon nanotube film is obtained by drawing from a carbon nanotube array, and comprises a plurality of carbon nanotubes which are oriented substantially in the same direction and are arranged parallel to the surface of the carbon nanotube film. The carbon nanotubes are connected end to end by Van der Waals force. The plurality of carbon nanotube films in the carbon nanotube film structure 122 are interdigitated and laminated. Since the carbon nanotubes in each layer are arranged in a preferred orientation in one direction, the carbon nanotubes in the adjacent two layers of carbon nanotube membranes have an intersection angle α, 0° < α≦ 90°. This embodiment is preferably α = 90°. A plurality of rectangular micropores 126 can be defined by 90° mutually intersecting carbon nanotubes, thereby providing a reference coordinate to the sample particles when the sample particles are observed using the TEM microgrid 100, facilitating the positioning and identification of the sample particles.

Referring to FIGS. 5 and 7, the carbon nanotube membrane structure 122 includes a plurality of intersecting nano carbon pipelines 128 including carbon nanotubes stacked side by side and gathered by van der Waals force, further The nanocarbon line 128 includes carbon nanotubes that are connected end to end by van der Waals force and are arranged in a preferred orientation along substantially the same direction. The intersecting nanocarbon line 128 defines a plurality of micropores 126 in the carbon nanotube membrane structure 122. The size of the micropores 126 of the carbon nanotube membrane structure 122 is related to the number of layers of the carbon nanotube membrane. The number of layers of the carbon nanotube film in the carbon nanotube film structure 122 is not limited, and is preferably 2 to 4 layers. The pores 126 in the carbon nanotube membrane structure 122 may have a size of from 1 nm to 1 μm, and preferably, the pores of 100 nm or less may reach 60% or more.

The functionalized graphene sheet 124 includes one or more layers of graphene having a size greater than the size of the micropores 126 in the carbon nanotube membrane structure 122 and completely covering the microholes 126. The functionalized graphene sheet 124 has a size of 2 nm to 100 μm. Preferably, the functionalized graphene sheet 124 has a size of from 2 nm to 50 microns. In this embodiment, a graphene oxide sheet is used, and the graphene oxide sheet includes one to three layers of graphene oxide.

Further, the carbon atoms in the functionalized graphene sheet 124 are in the carbon nanotube The carbon atoms can be bonded by sp3 hybridization to stably immobilize the functionalized graphene sheet 124 on the carbon nanotube film structure 122. Alternatively, when the carbon nanotube film structure 122 has at least one chemical functional group, the functional group in the functionalized graphene sheet 124 may be chemically bonded to the functional group in the carbon nanotube film structure 122. That is, the bond between the functionalized graphene sheet 124 and the carbon nanotube film structure 122 can be linked by a van der Waals force, a covalent bond between carbon atoms, or a chemical bond between functional groups.

Further, the graphene-carbon nanotube composite film 120 may include a plurality of carbon nanotube film structures 122 stacked and a plurality of functionalized graphene sheets 124 respectively disposed on adjacent two carbon nanotube film structures 122. between. Referring to FIG. 8, the functionalized graphene sheet 124 can be disposed between the two carbon nanotube film structures 122 and sandwiched by the nano carbon line 128 in the two carbon nanotube film structure 122, thereby functionalizing the functionalized Graphene sheets 124 are stably attached to the carbon nanotube film structure 122.

The support body 110 can be a metal piece having one or a plurality of through holes 112. The support 110 can be a metal mesh commonly used in transmission electron microscopes. The metal mesh is made of copper or other metallic materials. The graphene-carbon nanotube composite film 120 substantially covers the support body 110, so that the graphene-carbon nanotube composite film 120 can be partially suspended by the support body 110. In the embodiment, the graphene- The carbon nanotube composite film 120 has the same area and shape as the support 110 and completely covers all the through holes 112 of the support 110. In addition, the diameter of the through hole 112 of the support body 110 may be much larger than the size of the micro holes 126 of the carbon nanotube film structure 122 and larger than the size of the functionalized graphene sheet 124. In this embodiment, the through hole 112 of the support has a diameter of 10 micrometers to 2 millimeters.

It can be understood that the TEM micro-gate 100 can also adopt other materials (such as ceramics, glass). A mesh made of glass or quartz is used as the support body 110 instead of the metal mesh.

In the embodiment, the TEM micro-gate 100 is applied, and the sample 200 to be observed is disposed on the surface of the TEM micro-gate 100. Specifically, referring to FIG. 9 and FIG. 10, the sample 200 is disposed on the surface of the functionalized graphene sheet 124 covering the micropores 126 of the carbon nanotube film structure 122. The sample 200 can be a nanoparticle such as a nanowire, a nanosphere or a nanotube. The sample 200 may have a size of less than 1 micron, preferably less than 10 nanometers. Please refer to FIG. 10 and FIG. 11 , which are TEM images of different resolutions obtained by adding a nano-gold dispersion droplet to the surface of the TEM micro-gate 100 and drying under a transmission electron microscope. The black particles in the figure are the nano gold particles to be observed.

The TEM micro-gate 100 provided by the embodiment of the present invention has the following advantages.

First, the functionalized graphene sheet 124 functions as a carrier sample 200, and a large amount of sample 200 can be uniformly distributed on the surface of the functionalized graphene sheet 124, which can be used to measure the statistical distribution of the particle size of the sample 200, and observe that the large amount of sample 200 is functionalized. Self-assembly characteristics of the surface of graphene sheet 124. Since the functionalized graphene sheet 124 covers the micropores 126, the sample 200 can be carried by the functionalized graphene sheet 124 to be evenly distributed over the micropores 126 of the carbon nanotube membrane structure 122, thereby improving the The carrying probability of the TEM microgrid 100 on the sample and the support performance of the TEM microgrid 100 on the sample are improved.

Secondly, compared to the graphene sheets, the functionalized graphene sheets 124 are more easily spread out on the surface of the carbon nanotube film structure 122 to form a substrate of uniform thickness, avoiding the influence of the observation of the sample 200 distributed thereon. .

Again, the size of the functionalized graphene sheet 124 prepared in the previous method is smaller because Therefore, since the carbon nanotube film structure 122 has nano-scale micropores 126 (having a size of 1 nm or more and less than 1 μm), the size of the functionalized graphene sheet 124 does not need to be too large, and the entire surface can be completely covered. The micropores 126, so that the permeable micromirror 100 can be used to maximize the effective area of the observation, avoiding the situation that the functionalized graphene sheet 124 cannot completely cover the micropores due to the excessive micropores.

Fourth, the graphene sheet has an extremely thin thickness, and the thickness of the single-layer graphene is about 0.335 nm, and the contrast noise generated in the transmission electron microscope observation is small, so that a higher resolution TEM image can be obtained. Additionally, metal meshes having small diameter (e.g., below 2 microns) vias are fabricated by photolithography or other complex and costly processes. In this embodiment, the diameter of the support body 110 does not need to be small, so the cost of the support body 110 is greatly reduced.

Fifth, since the carbon nanotube film obtained for drawing from the carbon nanotube array is high in purity, it is not necessary to remove impurities by heat treatment. The method for preparing the carbon nanotube film is simple, and is advantageous for reducing the cost of the TEM microgrid 100. In the present embodiment, the transmission electron microstrip microgrid 100 has little interference to the morphology and structural analysis of the sample to be observed carried thereon, and has little influence on the high resolution image of the nanoparticle sample.

Further, since the carbon nanotube film structure 122 and the functionalized graphene sheet 124 are both formed by carbon atom bonding and have a similar structure, the carbon nanotube film structure 122 and the functionalized graphene sheet 124 have good properties. The matching property can be formed by a covalent bond between carbon atoms or a bond between functional groups to facilitate the use or long-term preservation.

In addition, the graphene-carbon nanotube composite film 120 may include at least two carbon nanotube film structures 122 and sandwich work disposed between the two graphene-carbon nanotube composite films 120. The graphene sheet 124 can be made. Such a structure allows the TEM microgrid 100 to have a more stable structure for re-use or long-term storage.

It will be understood by those skilled in the art that the micropores in the above graphene oxide sheet and the carbon nanotube film structure are rectangular or irregular polygonal structures, and the size of the above graphene oxide sheet refers to a point from the edge of the graphene oxide sheet. The maximum linear distance to another point, the size of the micro-hole refers to the maximum linear distance from one point to another point in the micro-hole.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by those skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

100‧‧‧ Transmission electron microscopy

110‧‧‧Support

112‧‧‧through hole

120‧‧‧graphene-nanocarbon tube composite film

Claims (12)

A method for preparing a transmission electron microstrip microgate, comprising the steps of: providing a functionalized graphene sheet dispersion and a carbon nanotube membrane structure, the nanocarbon tube membrane structure having a plurality of micropores; the functionalized graphite The olefin dispersion disperses the surface of the carbon nanotube film structure; drying the carbon nanotube film structure infiltrated by the functionalized graphene sheet, thereby compounding the functionalized graphene sheet with the carbon nanotube film structure, Forming a graphene-nanocarbon tube composite film; and providing at least one support body having at least one through hole, the graphite-carbon nanotube composite film covering the through hole of the support. The method for producing a TEM microgate according to claim 1, further comprising the step of heat-treating the graphene-carbon nanotube composite film in a vacuum or a shielding gas. The method of producing a TEM microgate according to claim 2, wherein the heat treatment has a temperature of from 100 ° C to 300 ° C. The method of preparing a TEM microgate according to claim 1, further comprising the step of treating the at least one carbon nanotube film structure with a volatile organic solvent. The method for preparing a TEM micro-gate according to claim 1, further comprising the step of covalently functionalizing the structure of the carbon nanotube film, the method for covalently functionalizing the structure of the carbon nanotube film To: immerse the carbon nanotube membrane structure in a functionalized solution and wash it with deionized water. A method of preparing a TEM microgrid according to claim 1, wherein the functionalization is performed After the graphene sheet dispersion infiltrates the surface of the carbon nanotube film structure, further comprising covering another surface of the carbon nanotube film structure with the surface of the carbon nanotube film structure infiltrated by the functionalized graphene sheet dispersion, The step of forming a sandwich structure. The method for preparing a TEM micro-grid according to claim 1, wherein after drying the carbon nanotube film structure infiltrated by the functionalized graphene sheet, further comprising irradiating the graphene-naphthalene with laser or ultraviolet light. a carbon nanotube composite membrane; or a step of bombarding the graphene-nanocarbon nanotube composite membrane with high energy particles to bond the functionalized graphene sheet to the carbon nanotube. The method for preparing a TEM micro-grid according to claim 1, wherein after the graphene-carbon nanotube composite film covers the support, further comprising treating the graphene-nanocarbon with an organic solvent The step of combining the tube composite membrane with the support body is tight. The method for preparing a TEM micro-grid according to claim 1, wherein after the graphene-carbon nanotube composite film covers the support, further comprising removing excess graphene-nano along the edge of the support The step of the carbon tube composite membrane. The method of preparing a TEM micro-gate according to claim 1, wherein the method of covering the support by the graphene-carbon nanotube composite film further comprises the steps of: providing a plurality of support spacers; The graphene-nanocarbon tube composite film is entirely covered on the plurality of supports; and the graphene-nanocarbon tube composite film is disconnected from between two adjacent supports to form a plurality of surface covers at a time A support having a graphene-nanocarbon tube composite membrane. The method for producing a TEM microgrid according to claim 9 or claim 10, wherein the removing the excess graphene-carbon nanotube composite film or from the adjacent two supports The method of breaking the graphene-nanocarbon tube composite film is to focus and irradiate the graphene-nanocarbon tube composite film with a laser beam. The method for preparing a TEM micro-gate according to claim 11, wherein the carbon nanotube film structure comprises a plurality of cross-laminated carbon nanotube films, wherein the carbon nanotube film is an array of carbon nanotubes Directly pulled in.