TWI413150B - Transmission electron microscope grid and method for making same - Google Patents

Abstract

The present invention relates to a transmission electron microscope grid. The transmission electron microscope grid includes a carrier and a graphene layer-carbon nanotubes film composite structure covered on the carrier. The carrier includes at least one through hole. The graphene layer-carbon nanotubes film composite structure includes a graphene layer and at least one carbon nanotubes film structure. The carbon nanotubes film structure includes a plurality of micropores. The micropores of the carbon nanotubes film structure are covered by the graphene layer. The present invention also relates to a method for making the transmission electron microscope grid.

Description

Transmission electron micro-gate and preparation method thereof

The invention relates to a TEM micro-grid and a preparation method thereof, in particular to a TEM micro-gate using a carbon nanotube film structure and a preparation method thereof.

In transmission electron microscopy, the microgrid is used to carry powder samples and is an important tool for high resolution image (HRTEM) observation of 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 coating a porous organic film on a metal support such as a copper mesh or a nickel mesh, and then vapor-depositing an amorphous carbon film. However, in practical applications, when observing the high-resolution image of the TEM of the nano-sized particles, the amorphous carbon film in the micro-gate is thicker, the contrast noise is larger, and the transmission electron microscope imaging resolution of the nano-sized particles is The impact is greatly increased, especially for particles smaller than 5 nm in size.

In view of this, it is necessary to provide a TEM micro-grid which is more easily obtained with a high-resolution image of a transmission electron microscope for a nano-sized particle and a preparation method thereof.

A TEM microgrid comprising a carrier, the carrier comprising at least one via, wherein the TEM microgate further comprises a via covering the carrier Graphene layer-nanocarbon tube film composite structure, the graphene layer-nanocarbon tube film composite structure comprises a graphene layer and at least one layer of carbon nanotube film structure, the carbon nanotube film structure has A plurality of micropores, the graphene layer covering the plurality of micropores and being suspended by the plurality of micropores.

A method for preparing a transmission electron microstrip, comprising the steps of: providing a substrate and forming a graphene layer on the surface of the substrate; providing a carbon nanotube film structure having a plurality of micropores Covering the surface of the graphene layer with the film structure of the carbon nanotube to form a three-layer structure of a base-graphene layer-carbon nanotube film structure; removing the base-graphene layer-nanocarbon a substrate in a three-layer structure of a tubular film structure to obtain a graphene layer-nanocarbon tube film composite structure; and covering the graphene layer-carbon nanotube film composite structure with a carrier to make a carbon nanotube The film structure is in direct contact with the carrier.

Compared with the prior art, the TEM microgrid and the preparation method thereof can prevent the destruction of graphene without destroying or reducing the damage by reducing the film structure of the carbon nanotube as a self-supporting and viscous support skeleton. Under the condition of the layer, the graphene layer is conveniently transferred from the substrate and stably adhered to the surface of the carbon nanotube film structure, thereby preparing a graphene layer-nanocarbon tube film composite structure having a size of centimeter; and The olefin layer has an extremely thin thickness, and the contrast noise generated in the transmission electron microscope observation is small, so that a TEM image with a higher resolution can be obtained.

100,200‧‧‧ TEM microgrid

110,210‧‧‧Metal carrier

112,212‧‧‧through holes

120,220‧‧‧graphene layer-nano carbon nanotube film composite structure

122,222‧‧‧Nano carbon tube membrane structure

124,224‧‧‧graphene layer

126,226‧‧‧micropores

128,228‧‧‧Nano carbon pipeline

1 is a schematic view showing the structure of a transmission electron microscope micro-gate according to a first embodiment of the present invention.

2 is a graphene layer-nanocarbon in a TEM microgrid according to a first embodiment of the present invention; Schematic diagram of the structure of the tubular composite structure.

3 is a transmission electron micrograph of a graphene layer-carbon nanotube film composite structure in a TEM microgrid according to a first embodiment of the present invention.

4 is a scanning electron micrograph of a single-layered carbon nanotube film in a graphene layer-nanocarbon tube film composite structure in a TEM microgrid according to a first embodiment of the present invention.

5 is a scanning electron micrograph of a multilayer carbon nanotube film in a graphene layer-nanocarbon tube film composite structure in a transmission electron microscope micro-gate according to a first embodiment of the present invention.

Figure 6 is a high resolution transmission electron micrograph of a nano gold particle carried on a graphene surface using a transmission electron microstrip microgrid according to a first embodiment of the present invention.

FIG. 7 is a flow chart of a method for preparing a TEM micro-gate according to a first embodiment of the present invention.

FIG. 8 is a schematic structural view of a TEM micro-gate according to a second embodiment of the present invention.

FIG. 9 is a schematic structural view showing a graphene layer-carbon nanotube film composite structure in a transmission electron microscope micro-gate according to a second embodiment of the present invention.

The invention will be further described in detail below with reference to the drawings and specific embodiments.

Referring to FIG. 1 , FIG. 2 and FIG. 3 , a first embodiment of the present invention provides a TEM micro-gate 100. The TEM micro-gate 100 includes a metal carrier 110 and a graphene layer covering the surface of the metal carrier 110 . - a carbon nanotube film composite structure 120. Wherein, the graphene layer-carbon nanotube film composite structure 120 includes at least one layer of carbon nanotube film structure 122 and a graphene layer 124, the nanometer The carbon tube film structure 122 is in direct contact with the metal carrier 110. The carbon nanotube film structure 122 has a plurality of micropores 126 disposed on the surface of the carbon nanotube film structure 122 and covering the plurality of carbon nanotube film structures 122. The micropores 126, the graphene layer 124 is suspended at a position at the micropore 126. Preferably, the TEM micro-gate 100 is a disk-like structure having a diameter of 3 mm and a thickness of 3 to 20 μm.

The metal carrier 110 includes at least one through hole 112. The shape of the at least one through hole 112 may be a circle, a quadrangle, a hexagon, an octagon or an ellipse. It can be understood that the metal carrier 110 mainly functions as a mechanically-loaded graphene layer-carbon nanotube film composite structure 120 and a conductive effect of preventing electrons from accumulating in the TEM micro-gate 100 when the TEM 100 is in use. The graphene layer-carbon nanotube film composite structure 120 completely covers the metal carrier 110. The graphene layer-carbon nanotube film composite structure 120 is suspended at a position of the through hole 112 of the metal carrier 110. Specifically, the metal carrier 110 is formed with a plurality of through holes 112. The size of the through hole 112 is larger than the size of the micro hole 126 in the carbon nanotube film structure 122, and the size of the through hole 112 may be 1 micrometer to 2 mm. The size of the microhole 126 refers to the maximum linear distance from one point to another point in the microhole 126. It can be understood that the shape and arrangement of the plurality of through holes 112 are not limited, and can be adjusted according to actual application requirements. The distance between the plurality of through holes 112 may be equal or unequal. Preferably, the metal carrier 110 has a plurality of uniformly distributed vias 112 with a distance between adjacent vias 112 greater than 1 micron. The material of the metal carrier 110 may be copper, nickel or other metal materials, and the plurality of through holes 112 of the carrier 110 may be formed by etching. .

It can be understood that the TEM micro-gate 100 can also replace the metal carrier 110 with a carrier made of other conductive materials such as alloy or ceramic.

In this embodiment, the metal carrier 110 is a circular copper piece having a diameter of 3 mm, and the graphene layer-carbon nanotube film composite structure 120 is also in the shape of a disk, and the diameter of the metal carrier 110 is The diameter of the graphene layer-carbon nanotube film composite structure 120 is equal. The through holes 112 are circular in shape, and the through holes 112 are evenly distributed on the metal carrier 110, and the distance between adjacent through holes 112 is equal. The through hole 112 has a diameter of between 100 micrometers and 1 millimeter.

The graphene layer-carbon nanotube film composite structure 120 is a two-layer composite structure. The graphene layer-carbon nanotube film composite structure 120 includes at least one layer of a carbon nanotube film structure 122 and a graphene layer 124. The graphene layer 124 is a continuous unitary structure and is disposed to overlap the carbon nanotube film structure 122. The overlapping arrangement means that the graphene layer 124 has exactly the same shape and area as the carbon nanotube film structure 122. When the graphene layer 124 is disposed on the surface of the carbon nanotube film structure 122, the The graphene layer 124 may completely cover the carbon nanotube film structure 122. It can be understood that the one graphene layer 124 is disposed on the surface of the carbon nanotube film structure 122, and the one graphene layer 124 can completely cover all the micropores 126 of the carbon nanotube film structure 122.

The graphene layer-carbon nanotube film composite structure 120 is disposed on a surface of the metal carrier 110, and the carbon nanotube film structure 122 and the metal carrier 110 contact. The carbon nanotube film structure 122 includes at least two laminated carbon nanotube films. Referring to FIG. 4, the carbon nanotube film is a self-supporting structure composed of a plurality of carbon nanotubes. The plurality of carbon nanotubes are arranged in a preferred orientation along the same direction, and the preferred orientation arrangement 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 self-supporting carbon nanotube film does not require a large-area carrier support, but can maintain a self-membrane state as long as the supporting force is provided 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 continuous carbon nanotubes extending through the end-to-end extension of the van der Waals force in the carbon nanotube film.

Specifically, most of the carbon nanotube membranes extending substantially in the same direction in the same direction are not absolutely linear, and may be appropriately bent; or may not be completely aligned in the extending direction, and may be appropriately deviated from the extending direction. Therefore, partial contact between the carbon nanotubes juxtaposed in the majority of the carbon nanotubes extending substantially in the same direction of the carbon nanotube film cannot be excluded.

Specifically, the carbon nanotube film comprises a plurality of continuous and aligned carbon nanotube segments. The plurality of carbon nanotube segments are connected end to end by van der Waals force. Each of the carbon nanotube segments includes a plurality of mutually parallel carbon nanotubes, and the plurality of mutually parallel carbon nanotubes are tightly coupled by van der Waals force. The carbon nanotube segments have any length, thickness, uniformity, and shape. The carbon nanotubes in the carbon nanotube film are arranged in a preferred orientation along the same direction.

When the carbon nanotube film structure 122 includes a plurality of layers of carbon nanotube film, the plurality of carbon nanotube films are interdigitated and stacked, because in each layer of the carbon nanotube film, the carbon nanotubes are along a The orientation is preferred, and the carbon nanotubes in the adjacent two layers of carbon nanotube film have an intersection angle α, 0° < α 90°.

The carbon nanotube film structure 122 includes a plurality of intersecting nano carbon lines 128, and the nano carbon line 128 includes a plurality of carbon nanotubes side by side and gathered by van der Waals force, and further, the nai The carbon steel line 128 includes carbon nanotubes that are connected end to end by van der Waals and are oriented substantially in the same direction. The intersecting nanocarbon line 128 forms a plurality of micropores 126 in the carbon nanotube film structure 122. The size of the micropores 126 of the carbon nanotube film structure 122 is related to the number of layers of the carbon nanotube film. 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 film structure 122 may have a size of from 1 nm to 1 μm.

In this embodiment, referring to FIG. 5, the carbon nanotube film structure 122 includes two layers of carbon nanotube films stacked in a stack. Each of the carbon nanotube membranes is a carbon nanotube membrane as shown in FIG. 4, and the carbon nanotubes in the carbon nanotube membrane extend substantially in the same direction. Nano in adjacent carbon nanotube film in the carbon nanotube film structure 122 The carbon lines 128 are perpendicular to each other, and a plurality of micropores 126 are formed in the carbon nanotube film structure 122, and the micropores 126 have a size of between 100 nm and 1 μm.

The graphene layer 124 is disposed on the surface of the carbon nanotube film structure 122, and the graphene layer of the plurality of micropores 126 located in the carbon nanotube film structure 122 is suspended. The graphene layer is used to carry a sample to be tested. The graphene layer 124 includes a single layer or a plurality of layers of graphene. Further, the carbon atoms in the graphene layer 124 may be bonded to the carbon atoms in the carbon nanotube by sp3 hybridization, thereby stably fixing the graphene layer 124 to the carbon nanotube film structure 122. .

In this embodiment, the graphene layer is in the form of a disk having a diameter of 3 mm and completely covering the carbon nanotube film structure 122. The graphene layer includes 1-3 layers of graphene, and the carbon atoms in the graphene layer 124 and the carbon atoms in the carbon nanotubes can be bonded by sp3 hybridization, thereby stably fixing the graphene layer 124 to the graphene layer 124. The carbon nanotube film structure 122.

In the embodiment of the present invention, the TEM micro-gate 100 is disposed on the surface of the TEM micro-gate 100 when applied. Specifically, the sample to be observed is placed on the surface of the graphene layer 124 covering the micropores 126. The sample may be a nanoparticle such as a nanowire, a nanosphere or a nanotube. Please refer to FIG. 6 , which is a transmission electron micrograph obtained by adding a nanometer gold particle dispersion droplet to the surface of the TEM microgrid 100 and drying it and then observing it under a transmission electron microscope. The black particles in the figure are the nano gold particles to be observed.

Referring to FIG. 7, the present invention further provides a method for fabricating the TEM micro-gate 100 of the first embodiment. The preparation method mainly includes the following steps. ( S101) providing a substrate and forming a graphene layer on the surface of the substrate; (S102) providing a carbon nanotube film structure, the carbon nanotube film structure having a plurality of micropores, the carbon nanotube a film-like structure covering the surface of the graphene layer to form a three-layer structure of a base-graphene layer-carbon nanotube film structure; (S103) removing the base-graphene layer-nanocarbon tube film structure a substrate in the three-layer structure to obtain a graphene layer-nanocarbon tube film composite structure; (S104) covering the graphene layer-nanocarbon tube film composite structure with a carrier to make a carbon nanotube film The structure is in direct contact with the carrier.

Step S101, providing a substrate and forming a graphene layer on the surface of the substrate.

The substrate is mainly used as a carrier for graphene growth and stabilization, and has a certain stability by itself, but can be removed by a chemical reaction method or a physical method. The substrate may be selected from metallic materials, alloy materials or metal oxide materials depending on the application. In this embodiment, a copper foil having an area of 2 cm 2 and a thickness of 25 μm is used as a substrate, and a uniform graphene layer is formed on the surface of the substrate by low pressure chemical vapor deposition.

The graphene layer is a continuous unitary structure composed of a single layer or a plurality of layers of graphene. Preferably, the number of layers of graphene in the graphene layer is 1-3 layers, so that the transmission electron micro-gate has better contrast. The graphene is a two-dimensional layered structure formed by carbon atom by sp2 hybridization. The graphene layer has a size of 3 mm to 2 cm. The size of the graphene layer refers to the maximum linear distance from one point of the graphene layer edge to another point. The graphene layer is evenly and uniformly covered on the surface of the copper foil substrate. The size of the graphene layer in this embodiment is 3 mm to 2 cm.

Step S102, providing a carbon nanotube film structure, the carbon nanotube film structure having a plurality of micropores, covering the surface of the graphene layer with the carbon nanotube film structure to form a base-graphite A three-layer structure of an olefin layer-nanocarbon tube film structure.

The carbon nanotube film structure comprises a plurality of layers of cross-laminated carbon nanotube films. The carbon nanotube film is obtained by directly pulling from a carbon nanotube array, and the preparation method thereof comprises the following steps:

First, an array of carbon nanotubes formed on a growth substrate is provided, the array being a super-aligned array of carbon nanotubes.

The carbon nanotube array is prepared by chemical vapor deposition, and the carbon nanotube array is a plurality of pure carbon nanotube arrays formed by carbon nanotubes which are parallel to each other and grow 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 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 Selecting one or a plurality of carbon nanotubes having a certain width, in this embodiment, preferably contacting the carbon nanotube array with a tape having a certain width to select one or a plurality of carbon nanotubes having a certain width; (b The selected carbon nanotubes are drawn at a certain speed 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.

In 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 effect of 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 so-called "self-supporting structure" means that the carbon nanotube film can maintain the shape of a film without being supported by a support. Referring to FIG. 4, the carbon nanotube film comprises a plurality of carbon nanotubes arranged in a preferred orientation in the same direction and connected end to end by van der Waals. The carbon nanotubes are arranged substantially in the stretching direction and parallel to the Nano carbon tube membrane surface. 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 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.

After the carbon nanotube film is prepared, the plurality of carbon nanotube films are laminated and cross-lapped to form the carbon nanotube film structure. 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 nanotubes in the adjacent carbon nanotube film in the film structure of the carbon nanotubes thus laid cross at a certain angle, and the film structure of the carbon nanotubes is also a self-supporting structure. The edge of the carbon nanotube film structure is fixed by the frame and is suspended by the frame portion.

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 to form a stable nanocarbon. Tube membrane structure. In the film structure of the carbon nanotubes, the number of layers of the carbon nanotube film is not limited, and the adjacent two layers of carbon nanotube film have an intersection angle α, 0° < α 90°. In this embodiment, the number of layers of the carbon nanotube film in the film structure of the carbon nanotubes is two, and the extending directions of the carbon nanotubes in the two layers of carbon nanotube film are perpendicular to each other.

After forming the film structure of the above carbon nanotube, the film structure of the carbon nanotube is covered on the surface of the graphene layer, and since the film structure of the carbon nanotube has a certain viscosity, when the carbon nanotube is used When the film structure is attached to the surface of the graphene layer, a three-layer structure of a base-graphene layer-carbon nanotube film structure is formed.

It can be understood that the preparation method of the three-layer structure of the base-graphene layer-carbon nanotube film structure may further include: treating the base layer of the substrate-graphene layer-carbon nanotube film structure with an organic solvent The structure is such that the carbon nanotube film structure is tightly bonded to the graphene layer, and this step is an optional step.

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 be compared with the carbon nanotube Good wettability. The step of treating with an organic solvent is specifically: uniformly depositing an organic solvent on the surface of the film structure of the carbon nanotube film in the three-layer structure of the substrate-graphene layer-carbon nanotube film structure and infiltrating the whole The carbon nanotube film structure, or the three-layer structure of the above-mentioned base-graphene layer-carbon nanotube film structure may be immersed in a container containing an organic solvent to infiltrate.

After the three-layer structure of the substrate-graphene layer-nanocarbon tube film structure is infiltrated by an organic solvent, the adjacent carbon nanotubes in the film structure of the carbon nanotubes are gathered and contracted into A spaced-apart nanocarbon pipeline comprising a plurality of carbon nanotubes connected end to end by van der Waals force. 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 cross each other after the organic solvent treatment , forming a plurality of micropores. The size of the micropores in the membrane structure of the carbon nanotubes is from 1 nm to 10 μm, preferably from 100 nm to 1 μm. In this embodiment, the intersection angle α=90°, so that the nanocarbon lines in the adjacent carbon nanotube film in the film structure of the carbon nanotubes substantially cross each other perpendicularly to form a large number of micropores. 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 three-layer structure of the substrate-graphene layer-nanocarbon tube film structure is treated by organic solvent infiltration, and the adjacent carbon nanotubes and graphene pass the attraction of van der Waals and the surface tension of the solvent. The effects are gathered together so that the carbon nanotube film structure and the graphene layer are tightly bonded.

Step S103, removing the substrate in the three-layer structure of the base-graphene layer-carbon nanotube film structure to obtain a graphene layer-carbon nanotube film composite structure.

The three-layer structure of the base-graphene layer-carbon nanotube film structure is immersed in a treatment liquid to chemically react the substrate with the treatment liquid until the substrate is removed, thereby preparing the graphene layer. - Nano carbon tube membrane composite structure. It can be understood that since the carbon nanotube film structure itself has a certain self-supporting effect, it can serve as a carrier in which the graphene layer is stably present without destroying or reducing the overall structure of the graphene layer. The treatment liquid may be an acid solution, a sputum solution or a salt solution depending on the substrate. The treatment liquid in this embodiment is a ferric chloride solution. The ferric ion in the ferric chloride solution may undergo an oxidation-reduction reaction with the copper foil substrate to remove the copper foil substrate. The graphene layer-carbon nanotube film composite structure can be stably present in the ferric chloride solution. The step of treating with the ferric chloride solution is specifically: the three-layer structure of the base-graphene layer-carbon nanotube film structure is immersed in a ferric chloride solution having a concentration of 0.5 g/mL for 24 hours. It can be understood that the etching time required for the copper foil substrate differs depending on the size and thickness of the substrate and the concentration of the treatment liquid used. Further, it is also possible to etch the copper foil substrate such as ferric chloride, iron sulfate, a mixture thereof or the like using other salt solution containing ferric iron.

After the above graphene layer-nanocarbon tube film composite structure is formed, the graphene layer-carbon nanotube film composite structure may be further washed using a cleaning liquid. Since the substrate chemically reacts with the treatment liquid, some metal ions are generated in the solution, and the metal ions are prone to hydrolysis reaction in the solution, thereby generating some particulate impurities. The graphene layer can be removed by further cleaning of the cleaning solution - particulate impurities in the carbon nanotube film composite structure.

The cleaning solution is an acid solution, and a mixture of one or more of dilute sulfuric acid, dilute hydrochloric acid and dilute nitric acid may be used. In the present embodiment, dilute hydrochloric acid is used. The cleaning solution can inhibit hydrolysis of the ferric chloride solution and remove particulate impurities in the graphene layer-carbon nanotube film composite structure. The specific step includes: immersing the graphene layer-carbon nanotube film composite structure in the cleaning solution for 1 min to 15 min.

After the graphene layer-carbon nanotube film composite structure is washed with a cleaning solution, the graphene layer-carbon nanotube film composite structure may be further washed with deionized water to remove the cleaning liquid. The graphene layer-carbon nanotube film composite structure is formed.

After forming the graphene layer-nanocarbon tube film composite structure, the graphene layer-carbon nanotube film composite structure may be further processed to make carbon atoms in the graphene layer and the carbon nanotube film The carbon atoms are bonded to each other.

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

Step S104, covering the graphene layer-carbon nanotube film composite structure with a carrier, and directly contacting the carbon nanotube film structure with the carrier.

First, at least one carrier is provided, the carrier comprising at least one through hole. The shape of the at least one through hole may be a circle, a quadrangle, a hexagon, an octagon, an ellipse or the like. It can be understood that the carrier mainly functions as a mechanically supported graphene layer-carbon nanotube film composite structure. Specifically, the carrier is formed with a plurality of through holes. The shape and arrangement of the plurality of through holes are not limited, and can be adjusted according to actual application requirements. The distance between the plurality of through holes may be equal or unequal. Preferably, the plurality of through holes are evenly distributed on the carrier, and a distance between adjacent through holes is greater than 1 micrometer. A plurality of vias of the carrier may be formed by etching. In this embodiment, a plurality of carriers are provided and the carriers are arranged at intervals. The carrier is a very thin round copper sheet. The carrier has a plurality of circular through holes having a pore diameter of between 100 micrometers and 1 millimeter and uniformly distributed over the carrier, and a distance between adjacent via holes is greater than 1 micrometer.

Next, the graphene layer-carbon nanotube film composite structure covers the plurality of carriers to directly contact the film structure of the carbon nanotubes with the carrier.

Then, the graphene layer-carbon nanotube film composite structure is disconnected from the adjacent two carriers.

Specifically, a laser beam may be used to focus and illuminate between two adjacent carriers to blow the graphene layer-carbon nanotube film composite structure. In this embodiment, the laser beam power is 5 to 30 watts (W), preferably 18 watts.

Further, the graphene layer-carbon nanotube film composite structure covering the carrier may be treated with an organic solvent, so that the graphene layer-carbon nanotube film composite structure and the carrier are tightly combined, and excess is removed along the carrier edge. Graphene layer - nano The carbon tube film composite structure is made into 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 layer-carbon nanotube film composite structure, so that the graphene layer-nanocarbon tube film composite structure and the carrier are tightly combined. Alternatively, the above-mentioned carrier covered with the graphene layer-carbon nanotube film composite structure may be entirely immersed in a container containing an organic solvent to be infiltrated. The step of removing the excess graphene layer-nanocarbon tube film composite structure other than the carrier may be performed by focusing a laser beam and irradiating the edge of the carrier for one week to ablate the graphene layer-carbon nanotube film composite structure. Thereby, the excess graphene layer-nanocarbon tube film composite structure outside the carrier is removed. This step is an optional step.

Referring to FIG. 8 and FIG. 9, a second embodiment of the present invention provides a TEM micro-gate 200. The TEM micro-gate 200 is a disk-like structure having a diameter of 3 mm and a thickness of 3 to 20 micrometers. The TEM micro-gate 200 includes a metal carrier 210 and a graphene layer-carbon nanotube film composite structure 220 covering the surface of the metal carrier 210. The graphene layer-carbon nanotube film composite structure 220 includes a two-layered carbon nanotube film structure 222 and a graphene layer 224.

The graphene layer 224 is disposed between the two layers of carbon nanotube film structure 222, that is, the graphene layer 224 is held between the two layers of carbon nanotube film structure 222, thereby making the graphite The olefin layer 224 is stably fixed between the two-layered carbon nanotube film structure 222. The carbon nanotube film structure 222 includes a plurality of micropores 226, each of which is covered by the one graphene layer 224.

The structure of the metal carrier 210, the two-layered carbon nanotube film structure 222, and the graphene layer 224 are respectively related to the metal carrier 110 and the carbon nanotube film structure in the first embodiment of the present invention. 122 and the graphene layer 124 are the same.

The invention further provides a preparation method of the second embodiment TEM micro-gate, the preparation method comprising the following steps.

S201: providing a substrate and forming a graphene layer on the surface of the substrate.

S202: providing a carbon nanotube film structure, the carbon nanotube film structure having a plurality of micropores, covering the surface of the graphene layer with the carbon nanotube film structure to form a base-graphene Layer-nanocarbon tube membrane structure three-layer structure.

S203: removing the substrate in the three-layer structure of the base-graphene layer-carbon nanotube film structure to obtain a graphene layer-carbon nanotube film composite structure.

The three steps are the same as the first three steps of the preparation method of the TEM micro-gate of the first embodiment of the present invention.

S204: after forming the graphene layer-nanocarbon tube film composite structure, further covering another surface of the graphene layer in the graphene layer-carbon nanotube film composite structure, A sandwich structure is formed on the two sides of which is a graphene layer in the middle of the carbon nanotube film structure; the sandwich structure is covered with a carrier to form a transmission electron microscope microgrid.

It is to be understood that the other carbon nanotube film structure may comprise a single layer or a plurality of layers of carbon nanotube film, and may have the same or different structure as the film structure of the carbon nanotube of the first embodiment of the present invention. The sandwich structure is a two-layer carbon nanotube film structure and A three-layer sandwich structure formed by a layer of graphene. The two-layered carbon nanotube film structure holds the intermediate graphene layer, so that the graphene layer is more firmly fixed. After the sandwich structure is formed, the sandwich structure may be further treated with a volatile organic solvent in step S102 in the first embodiment, thereby forming a plurality of micropores in the other carbon nanotube film structure and allowing another The carbon nanotube film structure is tightly bonded to the graphene layer.

The TEM microgate provided by the embodiment of the invention has the following advantages:

First, the graphene layer functions as a sample bearing, and a large number of samples can be uniformly distributed on the surface of the graphene layer, which can be used to measure the statistical distribution of the particle size of the sample, and observe the self-assembly characteristics of the large amount of the sample on the surface of the graphene layer. Since the graphene layer covers the micropores in the film structure of the carbon nanotube, the sample can be carried by the graphene layer and uniformly distributed over the micropores, thereby improving the TEM microgate to the sample. Carrying probability. Further, the particle diameter of the sample to be tested is not limited, and for example, only a sample slightly smaller than the micropore may be used.

Second, the graphene layer has a larger size, up to the centimeter scale, and can completely cover the micropores so that the microgrid can be used to observe and characterize the effective area of the sample to a maximum. In addition, since the graphene layer is a continuous integral structure, the surface thereof is flat, and no obvious gap is formed, which is advantageous for observation of the sample to be tested.

Third, graphene 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. In addition, because the graphene sheets are continuous The lamellar structure covers the metal carrier together with the carbon nanotube film structure, so the pore diameter of the metal carrier need not be small, and thus the cost of the metal carrier is greatly reduced.

Fourth, since the carbon nanotube film structure is obtained by extracting from a carbon nanotube array, the carbon nanotubes in the carbon nanotube film in the carbon nanotube film structure are substantially the same The orientation is preferentially oriented, and the carbon nanotube film structure has high purity. Therefore, the TEM microgrid of the embodiment has little interference to the morphology and structure analysis of the sample to be observed carried thereon, and the nanoparticle is The high resolution image of the sample has little effect. In addition, the method for preparing the film structure of the carbon nanotubes is simple, and is advantageous for reducing the cost of the TEM microgate.

Further, since the carbon nanotube film structure and the graphene layer are both formed by carbon atom bonding and have a similar structure, the carbon nanotube film structure has good matching with the graphene layer and can pass The treatment forms sp3 covalent bonds to form a unitary structure that is easy to use or long-term storage.

In addition, the graphene layer-carbon nanotube film composite structure may include at least two layers of carbon nanotube film structures, and the graphene layer is disposed between the two layers of carbon nanotube film structures. Such a structure allows the TEM microgrid to have a more stable structure, which is convenient for repeated use or long-term storage.

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 structure is self-supporting and viscous, it is convenient to transfer the graphene layer from the substrate and stably adhere to the nanoparticle without destroying or reducing the damage of the graphene layer. Carbon tube membrane structure surface Thereby, a graphene layer-nanocarbon tube film composite structure having a size of up to centimeter is prepared. In addition, since the formation of the graphene layer-carbon nanotube film composite structure is mainly carried out in a solution, it is convenient to add various solutions to clean the formed graphene layer-nanocarbon tube film composite structure and remove Impurities in the graphene layer-nanocarbon tube film composite structure. Secondly, the method of treating the graphene layer-carbon nanotube film composite structure by using laser, ultraviolet light or high energy particles enables the graphene layer and the carbon nanotube film to be more firmly bonded by a covalent bond. Again, since the carbon nanotube film structure has a large specific surface area, it has a large viscosity and can adhere well to the carrier, and the carbon nanotube film structure and the carrier are treated by an organic solvent. The combination is stronger. Further, the graphene layer-carbon nanotube film composite structure can be covered on a plurality of carriers at one time, and the method is simple and rapid, and can be prepared in batch by removing the graphene layer-nanocarbon tube film composite structure other than the carrier. A stable TEM microgrid.

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‧‧‧Metal carrier

112‧‧‧through hole

120‧‧‧graphene layer-nano carbon nanotube film composite structure

122‧‧‧Nano Carbon Tube Membrane Structure

124‧‧‧graphene layer

Claims (24)

A TEM micro-gate comprising a carrier, the carrier comprising at least one via hole, wherein the TEM micro-gate further comprises a graphene layer-carbon nanotube film composite structure covering the carrier via hole, The graphene layer-nanocarbon tube film composite structure comprises a graphene layer and at least one layer of carbon nanotube film structure, the carbon nanotube film structure having a plurality of micropores, the graphene layer covering the A plurality of micropores are suspended by the plurality of micropores. The TEM microgrid according to claim 1, wherein the plurality of micropores of the carbon nanotube film structure are covered by the graphene layer. The TEM microgrid according to claim 1, wherein the graphene layer is disposed to overlap the carbon nanotube film structure. The TEM microgrid according to claim 1, wherein the graphene layer is a continuous unitary structure. The TEM micro-gate according to claim 1, wherein the graphene layer comprises 1 to 3 layers of graphene. The TEM microgrid according to claim 1, wherein the carbon nanotube film structure comprises a plurality of stacked carbon nanotube membranes, and the adjacent two layers of nanocarbon in the carbon nanotube membrane structure The carbon nanotubes in the tubular membrane cross at a certain angle. The TEM microgrid according to claim 6, wherein the carbon nanotube film comprises a plurality of carbon nanotubes extending substantially in the same direction. The TEM microgrid according to claim 7, wherein each of the carbon nanotubes in the carbon nanotube film extending in the same direction and in the extending direction The upper adjacent carbon nanotubes are connected end to end by van der Waals force. The TEM microgrid according to claim 1, wherein the carbon nanotube film structure comprises a plurality of cross-set nano carbon pipelines, and the plurality of cross-set nano carbon pipelines are in the carbon nanotubes The plurality of micropores are formed in the film structure. The TEM microgrid according to claim 1, wherein the micropore has a size of from 1 nm to 10 μm. The TEM microgrid according to claim 1, wherein the carbon atoms in the graphene layer are bonded to the carbon atoms in the film structure of the carbon nanotube by sp3 hybridization. The TEM micro-gate according to claim 1, wherein the graphene layer-carbon nanotube film composite structure comprises a graphene layer and a two-layer carbon nanotube film structure, wherein the graphene layer is held in a Between the two layers of carbon nanotube film structure. The TEM microgrid according to claim 1, wherein the through hole has a pore diameter of 1 μm to 2 mm. The TEM microgrid according to claim 1, wherein the material of the carrier is a metal, an alloy or a ceramic. A method for preparing a TEM micro-gate, comprising the steps of: providing a substrate and forming a graphene layer on the surface of the substrate; providing a carbon nanotube film structure having a plurality of micro-film structures a hole, covering the surface of the graphene layer with the carbon nanotube film structure to form a three-layer structure of a base-graphene layer-carbon nanotube film structure; removing the base-graphene layer-nano a substrate in a three-layer structure of a carbon tube film structure to obtain a graphene layer-nanocarbon tube film composite structure; and covering the graphene layer-carbon nanotube film composite structure with a carrier to make a nano The carbon tube membrane structure is in direct contact with the carrier. The method of producing a TEM microgate according to claim 15, wherein the substrate is a metal substrate, an alloy substrate or a metal oxide substrate. The method of preparing a TEM microgate according to claim 15, wherein the forming the three-layer structure of the base-graphene layer-carbon nanotube film structure further comprises treating the substrate with a volatile organic solvent. The three-layer structure of the graphene layer-nanocarbon tube membrane structure forms a plurality of micropores in the membrane structure of the carbon nanotubes, and the membrane structure of the carbon nanotubes is tightly bonded to the graphene layer. The method for producing a TEM micro-grid according to claim 15, wherein the method of removing the substrate in the three-layer structure of the base-graphene layer-carbon nanotube film structure is to use an acid, a hydrazine or a salt solution. A chemical reaction with the substrate to remove the substrate. The method for preparing a TEM microgate according to claim 15, wherein the substrate in the three-layer structure of the base-graphene layer-carbon nanotube film structure is removed to obtain a graphene layer-carbon nanotube After the film composite structure, further comprising irradiating the graphene layer-carbon nanotube film composite structure with laser or ultraviolet light, or bombarding the graphene layer-carbon nanotube film composite structure with high energy particles to make the graphene layer a step of bonding to the carbon nanotube film structure. The method for producing a TEM microgate according to claim 15, wherein the substrate in the three-layer structure of the base-graphene layer-carbon nanotube film structure is removed to form the graphene layer-nanocarbon After the tubular composite structure, the method further comprises covering another surface of the graphene layer in the graphene layer-carbon nanotube film composite structure to form a film on both sides of the carbon nanotube film. The sandwich structure in the middle of the structure is a graphene layer. The method for preparing a TEM micro-gate according to claim 15, wherein after the graphene layer-carbon nanotube film composite structure covers a carrier, the method further comprises treating the graphene layer with a volatile organic solvent. The carbon nanotube film composite structure and the carrier make the graphene layer-carbon nanotube film composite structure and the carrier tightly combined. The method for preparing a TEM micro-gate according to claim 15, wherein after the graphene layer-carbon nanotube film composite structure covers a carrier, further comprising removing excess graphene layer along the carrier edge - The steps of the carbon nanotube film composite structure. The method for preparing a TEM microgate according to claim 22, wherein the step of removing the excess graphene layer-carbon nanotube film composite structure along the edge of the carrier is to focus and irradiate the graphite with a laser beam. Alkene-nano carbon nanotube film composite structure. The method for preparing a TEM micro-gate according to claim 15, wherein the method of covering the graphene layer-carbon nanotube film composite structure with a carrier comprises the steps of: providing a plurality of carriers, the plurality of carriers being spaced apart Arranging; the graphene layer-carbon nanotube film composite structure entirely covers the plurality of carriers; and disconnecting the graphene layer-carbon nanotube film composite structure from between two adjacent carriers.