KR101000476B1 - Fabrication of Carbon Nanotube Thin Film with Macroporous and Mesoporous Structure - Google Patents

Abstract

The present invention relates to a three-dimensional porous carbon nanotube thin film having a mixed pupil structure of a macro-sized pupil and a meso-sized pupil and a method of manufacturing the same. According to the method of the present invention, it is possible to easily form a three-dimensional porous carbon nanotube thin film having a mixed pupil structure of macro-sized holes and meso-sized holes. The carbon nanotube thin film produced by the above method has a macroporous structure, which has a large specific surface area, and its structure is stable. In particular, the inner shape of the thin film has a porosity due to mesopores, and is very useful in energy storage materials (secondary batteries, fuel cells, supercapacitors), filtration membranes, chemical detectors, and gas sensors.

Carbon nanotubes, carbon nanotube thin films, macroporous structures, macropores, mixed pupil structures of nanopores, three-dimensional porous structures, surfactants, EASP devices

Description

Fabrication of Carbon Nanotube Thin Film with Macroporous and Mesoporous Structure

The present invention relates to a three-dimensional porous carbon nanotube thin film having a mixed pupil structure of a macro-sized pupil and a meso-sized pupil and a method of manufacturing the same.

Carbon nanotubes (CNTs), which are the result of ultra-fine technology "nanotechnology", the crystal of modern science and technology, are in the spotlight as materials with new properties and functions, unlike materials developed in the past. The science and technology industry, together with artificial organs and intelligent robots, has selected carbon nanotubes as 'the ten new technologies that will change the future' and is putting all its energy into technology development. Instead of silicon, carbon nanotubes have been applied to various applications such as semiconductor materials, electrode materials, etc. of nano robots, and their application ranges are widening.

Carbon nanotubes are carbon allotrope composed of carbon present on the earth in large quantity. Carbon nanotube is a substance formed by the combination of one carbon atom and other hexagonal honeycomb in the form of tube, and the diameter of the tube is nanometer (nm = 1 billion minutes). 1 meter) is a very small area of matter.

Carbon nanotubes have excellent mechanical robustness and chemical stability, show the electrical properties of conductors or semiconductors depending on the shape of the wound, have small diameters at the nanoscale, relatively long lengths, and hollow features. For this reason, carbon nanotubes are emitters of various devices, VFD (Vacuum Fluorescent Display), white light source, FED (Field Emission Display), energy storage materials (lithium ion secondary battery, hydrogen storage fuel cell, ultracapacitor) Electrode), nanowires, AFM / STM Tip, single-electron device, gas sensor, medical micro components, and high-performance composites. In order for the application technology of such carbon nanotubes to be put into practical use, thinning to nano size is essential. Accordingly, research on various thin film manufacturing methods as well as the production method of carbon nanotubes is actively underway.

In particular, if the structure consists of macro-sized pores in the carbon nanotube thin film, the specific surface area is increased and the electrolyte can be easily accessed when the energy storage material is applied, and thus high output characteristics can be expected.

Conventionally used macroporous carbon nanotube thin film manufacturing method can be largely classified into two types. First, the production of carbon nanotubes at the same time to produce a macroporous carbon nanotube thin film and the second commercially available carbon nanotube powder It is a method of manufacturing a macroporous carbon nanotube thin film using.

As a method of producing carbon nanotubes and simultaneously producing a macroporous carbon nanotube thin film, a chemical vapor deposition method and a method of self-assembly of carbon nanotubes using a water-spreading method have been reported (Chem. Commun. , 2002, 962, Angew. Chem. Int. Ed. 2004, 43, 1146)

As a method of preparing a macroporous carbon nanotube thin film using commercially available carbon nanotube powder, a solution casting process prepared by dispersing a powder of carbon nanotube in a solvent or a method of using SiO ₂ as a template has recently been reported. . (Adv. Mater. 2007, 19, 2535, Adv. Mater. 2008, 20, 457)

In order for the carbon nanotube thin film to be effectively applied to an application field, pore size and surface characteristics between carbon nanotubes must be controlled. However, the above methods have a problem that it is almost impossible to control the size of the pores when manufacturing the carbon nanotube thin film, and the process parameters, which are essential for forming the macroporous structure, include relative humidity, making it difficult to control the synthesis conditions. There is a problem that it is difficult to control the thickness in dimensions.

Therefore, when manufacturing a carbon nanotube thin film, it is possible to simply form a mixed pupil structure of macro-sized and meso-sized pores in the thin film, and to develop a method for manufacturing a three-dimensional porous carbon nanotube thin film that can effectively control the size of the pores. Is required.

The present invention

Acid treatment of the carbon nanotube powder;

Uniformly dispersing the carbon nanotube powder in a solvent;

Adding an anionic surfactant to the dispersed solution to prepare a precursor solution;

Forming a carbon nanotube thin film by electrostatically spraying the precursor solution on a substrate using an electrostatic aerosol spray pyrolysis (EASP) device;

Removing the anionic surfactant from the carbon nanotube thin film.

Provided are a three-dimensional porous carbon nanotube thin film manufacturing method having a macro-sized pore structure and a three-dimensional porous carbon nanotube thin film having a mixed pupil structure of a macro-sized pupil and a meso-sized pupil prepared accordingly.

According to the method of the present invention, it is possible to easily form a three-dimensional porous carbon nanotube thin film having macroscopic pores. The carbon nanotube thin film produced by the above method has a macroporous structure, which has a large specific surface area, and its structure is stable. In particular, the inner shape of the thin film has a porosity due to mesopores, and is very useful in energy storage materials (secondary batteries, fuel cells, supercapacitors), filtration membranes, chemical detectors, and gas sensors.

The present invention

Acid treatment of the carbon nanotube powder;

Uniformly dispersing the carbon nanotube powder in a solvent;

Adding an anionic surfactant to the dispersed solution to prepare a precursor solution;

Forming a carbon nanotube thin film by electrostatically spraying the precursor solution on a substrate using an electrostatic aerosol spray pyrolysis (EASP) device;

Removing the anionic surfactant from the carbon nanotube thin film.

Provided are a three-dimensional porous carbon nanotube thin film manufacturing method having a mixed pupil structure of a macro-sized pupil and a meso-sized pupil, and a three-dimensional porous carbon nanotube thin film having a mixed pupil structure of a macro-sized pupil and a meso-sized pupil. .

Figure 1 is a flow chart showing in detail each step of the carbon nanotube manufacturing method according to an embodiment of the present invention.

Hereinafter, a 3D porous carbon nanotube thin film manufacturing method according to the present invention will be described in detail with reference to FIG. 1.

Producing Solution Step

The first step of the method for producing a carbon nanotube thin film according to the present invention is the step 100 of treating the carbon nanotube powder with acid.

First, carbon nanotube (CNT) powder is prepared. The carbon nanotube powder used in the present invention is not particularly limited, and includes both single-walled carbon nanotubes, multi-walled carbon nanotubes, and mixtures thereof. In this case, since the general carbon nanotube powder exhibits hydrophobicity and does not disperse in a solvent such as water, the carbon nanotube powder is preferably subjected to an acid treatment step in order to impart hydrophilicity.

In the acid treatment step, the carbon nanotube powder is dissolved in a strong acid solution to dissolve and remove the metal catalyst included in the preparation of the carbon nanotube powder with a strong acid, and carbon nanotubes exhibiting hydrophobic properties not dispersed in a solvent such as water. A functional group is provided on the surface of the powder to impart hydrophilicity to the carbon nanotubes so that the carbon nanotube powders can be easily dispersed in the solvent.

In more detail, the acid treatment step, the carbon nanotube powder in an aqueous solution of a strong acid is added to the appropriate amount of heat is preferably treated by dipping at a temperature of about 60 to 90 ℃. The strong acid may be, for example, sulfuric acid, nitric acid, hydrochloric acid or a mixture thereof. At this time, if the temperature of the strong acid solution is less than 60 ℃ can not give chemical change to the chemically stable carbon nanotubes, it is difficult to impart hydrophilicity, if the temperature exceeds 90 ℃ strong acid may boil explosively and affect the surrounding environment And it is not desirable to have an accident. Therefore, the acid treatment step is preferably carried out in a strong acid solution in the above temperature range. In addition, an acid treatment time is not specifically limited, It is good to process two hours or more. If the treatment time is less than 2 hours, it may be difficult to impart hydrophilicity because the carbon nanotubes do not cause sufficient chemical deformation. At this time, even if the processing time is more than 6 hours, it is difficult to show the increased effect of increasing the time. Therefore, the acid treatment is preferably performed for 2 to 6 hours.

Thereafter, the carbon nanotubes are filtered and separated from the aqueous solution through a filter, and the filtered carbon nanotubes are washed several times with distilled water. Then, heat is applied to the cleaned carbon nanotubes to evaporate moisture to make the powder again.

The second step is to disperse the carbon nanotube powder in a solvent (200).

The carbon nanotube powder subjected to the acid treatment step is mixed with the solvent and then uniformly dispersed in the solvent.

At this time, the carbon nanotube powder is preferably mixed with the solvent at 0.001-4wt% based on the total solution. In general, the carbon nanotube powder is characterized in that the lower the mixing ratio of the total solution, the higher the dispersion ratio. However, according to the present invention, when the carbon nanotube powder is mixed with the solvent at less than 0.001 wt% with respect to the total solution, it is difficult to form a macro-sized pupil structure. On the other hand, when the carbon nanotube powder is mixed with the solvent in an amount exceeding 4wt%, the carbon nanotube powder is difficult to disperse in the solvent, and thus the carbon nanotube thin film cannot be manufactured.

In order to ensure that the carbon nanotube powder is well dispersed in the solvent, it is preferable to include the step of ultrasonic treatment to the mixture. Carbon nanotubes may have a long length relative to their diameter and may cause entanglement. The ultrasonic treatment may forcibly release carbon nanotubes to prevent entanglement. Therefore, the ultrasonic treatment together with the acid treatment can allow the carbon nanotubes to be uniformly dispersed in the solvent. The ultrasonic treatment is not particularly limited, and the intensity and time of the ultrasonic wave can be appropriately adjusted as necessary.

The solvent for dispersing the carbon nanotubes includes water, an organic solvent or a mixture thereof.

The solvent has a low boiling point, and it is preferable to use a solvent having a lower density than that of carbon nanotubes or silica. For example, a low boiling point such as water, acetone, alcohol (for example, methanol, ethanol, etc.) and a low density can be usefully used. The reason for this is as follows.

When spraying the precursor solution in which the carbon nanotubes and silica are dispersed through the EASP device on the substrate S, the solvent having a high boiling point does not evaporate smoothly so that the solvent is not easily deposited on the substrate S. Moreover, the characteristic of the thin film E formed on the board | substrate S can also be reduced. In addition, when the density of the solvent itself is high, the carbon nanotubes and the silica powder do not easily go through, so that it is difficult to smoothly disperse. Accordingly, the solvent has a relatively low boiling point, and it is preferable to use water, a ketone solvent, an alcohol solvent, or a mixture thereof having a lower density than carbon nanotubes.

When water is used as the sole dispersion solvent, the macroporous structure may not be partially formed in the resulting carbon nanotube thin film. In the case of using only an organic solvent, the dispersion rate of the carbon nanotube powder is low, and thus the carbon nanotube Difficulties may arise in the manufacture of thin films. Therefore, preferably, a mixture of water and an organic solvent can be used as the dispersion solvent. In this case, water and the organic solvent may be mixed in a volume ratio of 9: 1 to 1: 9. The organic solvent may be selected from, but not limited to, acetone, methanol, ethanol, propanol, isopropanol, butanol or mixtures thereof. The pore size may be controlled according to the type of the dispersion solvent.

In one embodiment of the invention, the solvent is a mixture of water and acetone. When the dispersion solvent is a mixture of water and acetone, the carbon nanotube particles may be easily injected into the aerosol state through the injector 10 of the EASP apparatus. In a preferred embodiment, acetone may be mixed at 20-30 vol% of the total mixed solution.

When using a mixture of water and an organic solvent as the dispersion solvent, each may be mixed simultaneously or sequentially. For example, after mixing water and an organic solvent first, carbon nanotubes may be added, or water or an organic solvent may be sequentially added to the carbon nanotubes. In an embodiment of the present invention, after the step of dispersing the carbon nanotube powder in water (200), the step of mixing the acetone solution (300).

The preparation of the precursor solution also includes a process 400 of adding an anionic surfactant. The addition of anionic surfactants is an essential process for the formation of macro sized pores. In the conventional method for producing a carbon nanotube thin film, a surfactant has been simply used as a dispersant. In addition, since the bottom substrate of the EASP device is negatively charged, it has been accepted that it is preferable to use a cationic surfactant so that the carbon nanotube particles in the sprayed precursor solution can be uniformly deposited on the substrate. According to the present invention, however, it was found that the use of anionic surfactants other than the cationic surfactants serves as a macroporous structure forming agent as well as a dispersant. In the case of using a cationic surfactant, if the surfactant is removed after the preparation of the carbon nanotube thin film, the resulting macroporous structure is collapsed, whereas in the case of using the anionic surfactant, even if the surfactant is removed, the macroporous The structure is kept stable.

The anionic surfactant that can be used as the macroporous structure former in the present invention may be any anionic surfactant known in the art. For example, the anionic surfactants include, but are not limited to, sodium dodecyl sulfate, alkylbenzene sulfonate, alpha olefin sulfonate, paraffin sulfonate, alkyl ester sulfonate, alkyl sulfate, alkyl alkoxy sulfate, alkyl sulfonate , Alkyl alkoxy carboxylates, alkyl alkoxylated sulfates, monoalkyl (ether) phosphates, dialkyl (ether) phosphates, sarcosinates, sulfosuccinates, isethionates, taurates, ammonium lauryl sulfates, ammonium laurate sulfates , Triethylamine lauryl sulfate, triethylamine laurate sulfate, triethanolamine lauryl sulfate, triethanolamine laurate sulfate, monoethanolamine lauryl sulfate, monoethanolamine laurate sulfate, diethanolamine lauryl sulfate, diethanol Amine Lauret Sulfate Sodium laurate monoglyceride sodium sulfate, sodium lauryl sulfate, sodium lauryl sulfate, potassium lauryl sulfate, potassium laurate sulfate, sodium lauryl phosphate, sodium tridecyl phosphate, sodium behenyl phosphate, sodium laurate 2 phosphate, sodium cetet-3 phosphate, sodium tridecet-4 phosphate, sodium dilauryl phosphate, sodium ditridecyl phosphate, sodium ditridecet-6 phosphate, sodium lauroyl sarcosinate, lauroyl sarco Gin, cocoyl sarcozin, ammonium cosyl sulfate, sodium cosyl sulfate, sodium tridecet sulphate, sodium tridecyl sulphate, ammonium tridecet sulphate, ammonium tridecyl sulphate, sodium cocoyl isethionate, disodium laureth sulfosuccinate Sinate, Sodium Methyl Oleoyl Taurate, Sodium Lauret Car Selected from the group consisting of carboxylate, sodium tridecetyl carboxylate, sodium lauryl sulfate, potassium kosyl sulfate, potassium lauryl sulfate, monoethanolamine kosyl sulfate, sodium tridecyl benzene sulfonate and sodium dodecyl benzene sulfonate May be one or more anionic surfactants.

In one embodiment of the invention, the anionic surfactant may be added in 0.002 to 50% by weight of the total solution. When the anionic surfactant is used in less than 0.002% by weight of the total solution may serve to help the dispersion of the carbon nanotube powder, but may not form a macro-sized pore structure. In addition, when the anionic surfactant is used in excess of 50% by weight of the total solution, the surfactant may not be completely dissolved in the solvent, which may interfere with the injection of carbon nanotubes, The move may not be desired.

Thin film forming step

In manufacturing the carbon nanotube thin film according to the present invention, the thin film is formed in the injection device capable of spraying the precursor solution and the generation of electrostatic fields (500). Preferably it is formed in the EASP device (electrostatic aerosol injection device) capable of controlling the injection amount and temperature of the precursor solution while being capable of spraying the precursor solution and generating the electrostatic field. Referring to FIG. 2, the EASP device will be described below.

Figure 2 shows a cross-sectional configuration of the EASP device preferably applied to the present invention.

Referring to FIG. 2, the EASP apparatus includes an injector 10 capable of injecting a precursor solution in an aerosol form; A substrate support 20 for supporting a substrate S and charging the substrate S; And a power generator 30 that provides a potential difference between the injector 10 and the substrate support 20. At this time, the EASP device comprises a heat supply means 25 for supplying heat to the substrate (S); A temperature controller 40 for controlling the temperature of the substrate S; And it is preferable to further include a flow controller 50 for controlling the injection amount of the precursor solution. In FIG. 2, reference numeral E denotes a thin film formed on the substrate S. In FIG.

In addition, a nozzle 15 is mounted at a lower end of the injector 10, and the high voltage DC power generator 30 is electrically connected to the nozzle 15 and the substrate support 20 of the injector 10 so that the injector ( A strong electrostatic field is formed between the substrate 10 and the substrate support 20. The flow controller 50 precisely controls the injection amount of the precursor solution by precisely adjusting the moving speed of the piston embedded in the injector 10, thereby freely adjusting the thickness of the thin film (E). Such a flow regulator 50 may preferably use an electronic flow regulator. In addition, the heat supply means 25 mounted in the substrate support 20 is included in the present invention as long as it can supply heat to the substrate 20 to evaporate the solvent of the precursor solution sprayed on the substrate S. do. For example, the heat supply means 25 may be selected from a lamp (eg, a halogen lamp), a resistance heating wire or a heater. The temperature controller 40 adjusts the temperature of the substrate S to be kept constant by controlling the heat supply means 25 by comparing the heat sensed by a temperature sensor such as a thermocouple with a preset heat. In addition, the EASP device may further include a distance adjuster (not shown) for adjusting the distance between the injector 10 and the substrate support 20.

According to the present invention, in the case of using the EASP device, the precursor solution is sprayed onto the substrate S by the electrostatic attraction to a uniform thickness, and the precursor solution sprayed by the heat generated from the heated substrate S together. Evaporation of the solvent in the carbon nanotube particles can be deposited to easily prepare the carbon nanotube thin film (E). That is, the mixed thin film E of carbon nanotubes and silica is fixed to the substrate S by evaporation without a separate drying process.

More specifically, the sprayed precursor solution is sprayed in a very small liquid droplet state that can overcome the surface tension of the solvent from the nozzle 15 under the influence of the applied electrostatic field during the spraying of the precursor solution, and the sprayed precursor solution moves along the electric field. And very evenly deposited on the negatively charged substrate.

At this time, the substrate (S) that can be used includes a conductor, a non-conductor and a semiconductor, for example, may be selected from materials such as glass, plastic and metal. The substrate S may be determined according to the use purpose and purpose of the thin film E. For example, a metal such as platinum (Pt), gold (Au), silver (Ag), or the like is deposited on a silicon (Si) body. Wafers can be used. In addition, the substrate S is mainly used as a current collector when manufacturing an electrode such as a capacitor (eg, an electric double layer capacitor (EDLC), etc.), and includes titanium (Ti), nickel (Ni), and aluminum (Al). And metal foils selected from these alloys and the like.

When spraying the precursor solution, the acceleration voltage of the EASP device is preferably between 6 and 15 kV. If it is out of the range, the porous structure may not be formed well, and the pore size may be controlled by adjusting the acceleration voltage.

At this time, it is good to maintain the temperature of the substrate (S) to about 100 ~ 250 ℃ through the temperature controller 40 of the EASP device. When the temperature is less than 100 ° C., all of the solvents (ethanol, etc.) contained in the injected precursor solution do not evaporate and thus are not deposited on the substrate S in an aerosol state, thereby deteriorating the characteristics of the thin film E. If the temperature is set above 250 ° C, the liquid in the droplet state evaporates before the solvent (ethanol, etc.) contained in the injected precursor solution arrives on the substrate S, so that the light carbon nanotube particles fly off into the air. This is because the amount deposited on the substrate S substantially decreases.

Surfactant Removal Steps

After forming the carbon nanotube thin film, the surfactant is removed (600). When the anionic surfactant is used as a macroporous structure forming agent, even if the surfactant is removed, the carbon nanotube thin film has three-dimensional porosity and maintains mechanical strength without breaking the pore structure.

The removing of the surfactant may be performed by, for example, impregnating the thin film of carbon nanotubes in water or an alcohol solution, and then washing several times with distilled water. At this time, the solution for removing the surfactant may be any one as long as it can remove the surfactant without affecting the pore structure of the carbon nanotube thin film.

The present invention will become more apparent with reference to the embodiments described below in detail. However, it will be understood that the present invention is not limited to the embodiments disclosed below, but may be embodied and implemented in various different forms.

Those skilled in the art will recognize that for processes and methods other than this disclosed herein, the functions performed in those processes and methods may be performed in other ways. In addition, the steps and processes outlined are provided by way of example only, and some of the steps and processes are optional and include additional steps and processes without combining the fewer steps and processes or impairing the subject matter of the present disclosure. Can be extended.

[Example]

First, carbon nanotube (CNT) powder was put in an aqueous sulfuric acid solution and acid-treated at 80 ° C. for 6 hours.

Water was added to the acid treated carbon nanotube (CNT) powder (0.07 wt% of carbon nanotubes), and the carbon nanotubes were uniformly dispersed in water by ultrasonic irradiation. To this was added an acetone solution such that water: acetone = 4: 1.

Sodium dodecyl sulfate as anionic surfactant was added 1 wt% with respect to the total solution.

The prepared precursor solution was sprayed and deposited on the substrate S using an EASP apparatus as shown in FIG. 1 to form a thin film E. FIG. At this time, the temperature of the substrate S was set at 150 ° C., the scanning speed was 1 ml / h, the distance between the nozzle 15 and the substrate S was 4 cm, and the acceleration voltage was 12 kV.

In order to remove the surfactant, the thin film was impregnated in an ethanol aqueous solution, and then washed several times with distilled water to prepare a carbon nanotube thin film according to the present embodiment.

Figure 3 is a SEM (Scanning Electron Microscopy) photographs showing the surface shape of the three-dimensional porous carbon nanotube thin film having a macroporous structure produced by the EASP device. 3A is a planar photograph taken at 1000 times the magnification of a thin film before removing the surfactant, and FIG. 3B is a photograph taken at 20,000 times in FIG. 3A. As can be seen in Figure 3a, macro-sized pores can be confirmed in the entire substrate, it can be seen that the carbon nanotubes and the surfactant is evenly mixed through Figure 3b. 3C and 3D are photographs taken at a magnification of 1000 times and 20,000 times, respectively, of the macroporous carbon nanotube thin film after removing the surfactant. It can be seen from FIG. 3c that the carbon nanotube thin film having the macroporous structure is maintained without collapse of the structure even after the surfactant is removed, and the surfactant is impregnated into the water / ethanol solution as shown in FIG. You can see that they are all removed. In addition, it can be seen in FIG. 3d that the macroporous structure wall is made of entangled carbon nanotubes.

4 is a SEM (Scanning Electron Microscopy) photograph showing the cross-sectional shape of the macroporous carbon nanotube thin film manufactured by the EASP device according to an embodiment of the present invention. 4A and 4B are photographs taken at a magnification of 2000 times and 20,000 times, respectively, of the thin film shape before removing the surfactant. 4C and 4D are photographs taken at 5000 times and 20,000 times the cross-sectional shapes of the macroporous carbon nanotube thin films after surfactant removal, respectively. In FIG. 4A, the carbon nanotube thin film having the macroporous structure has a thickness of about 13 μm, and the thickness of the carbon nanotube thin film of the present invention may increase or decrease in proportion to the amount and weight of the sprayed precursor solution. have. 4B, the carbon nanotubes are evenly mixed with the surfactant, and the macroporous structure is well grown in three dimensions.

It can be seen from FIG. 4c that the 3D porous structure of the macroporous structure is well maintained even after the surfactant is removed, and the thickness of the carbon nanotube thin film after the surfactant is removed is reduced to about 5 μm. . In addition, it can be seen that the three-dimensional porous structure of the macroporous structure is cylindrical. It can be seen from FIG. 4D that all of the surfactant is removed from the carbon nanotubes.

5 is a graph showing the size distribution of pores of macro size. This shows that the pore size is measured by about 130 times through 1000 times scanning electron micrograph, and it can be seen that the macro pore size distribution is concentrated on the basis of 1.5μm, and the average pore size is 1.43μm. You can check it.

Figure 1 shows a flow chart showing in detail the process of the manufacturing method of the three-dimensional porous carbon nanotube thin film having a mixed pupil structure of the macro-sized pupil and meso-sized pupil in accordance with an embodiment of the present invention.

Figure 2 shows a cross-sectional configuration of the EASP device preferably applied to the present invention.

3 is a SEM (Scanning Electron Microscopy) photograph showing the front surface shape of a carbon nanotube thin film having a mixed pupil structure of macro-sized and meso-sized pupils manufactured by the EASP apparatus, and FIGS. 3A and 3B are surfactant removal. It is the photograph which photographed the shape of the former thin film by 1000 times magnification and 20,000 times respectively. 3C and 3D are photographs taken at the same magnification as the shape of the carbon nanotube thin film after removing the surfactant, respectively.

FIG. 4 is a SEM (Scanning Electron Microscopy) photograph showing a cross-sectional shape of a carbon nanotube thin film having a mixed pupil structure of macro-sized and meso-sized pupils prepared through an EASP apparatus, and FIGS. 4A and 4B are before the removal of the surfactant. The cross-sectional shape of the thin film was taken at 2000 times and 20,000 times, respectively. 4C and 4D are photographs taken at 5000 times and 20,000 times the cross-sectional shapes of the carbon nanotube thin film after surfactant removal, respectively.

5 is a bar graph showing the size distribution of pores of macro size.

Description of the Related Art

10: injector 15: nozzle

20: substrate support 25: heat supply means

30: power generator 40: temperature controller

50: flow regulator S: substrate

Claims (16)

Acid treatment of the carbon nanotube powder; Uniformly dispersing the carbon nanotube powder in a solvent; Adding an anionic surfactant to the dispersed solution to prepare a precursor solution; Forming a carbon nanotube thin film by electrostatically spraying the precursor solution on a substrate using an electrostatic aerosol spray pyrolysis (EASP) device; Removing the anionic surfactant from the carbon nanotube thin film. A method for producing a three-dimensional porous carbon nanotube thin film having a mixed pupil structure of macro-sized pupils and meso-sized pupils. The process of claim 1 wherein the acid treatment is carried out in an aqueous strong acid solution at 60 to 90 ° C. The method of claim 1, wherein the carbon nanotube powder is dispersed in the solvent at 0.001 to 4 wt% based on the total solution. The method of claim 1, wherein the dispersion is performed by treating the mixture of carbon nanotube powder and a solvent with ultrasonic waves. The method of claim 1 wherein the solvent is selected from water, organic solvents or mixtures thereof. The method of claim 1, wherein the solvent is selected from water, acetone, methanol, ethanol, propanol, isopropanol, butanol or mixtures thereof. The method of claim 1, wherein the solvent is a mixture of water and an organic solvent in a volume ratio of 9: 1 to 1: 9. The method of claim 1 wherein said solvent is a mixture of water and acetone. The method of claim 8, wherein the acetone is mixed at 20-30 vol% of the total mixed solution. The method of claim 1, wherein the anionic surfactant is sodium dodecyl sulfate, alkylbenzene sulfonate, alpha olefin sulfonate, paraffin sulfonate, alkyl ester sulfonate, alkyl sulfate, alkyl alkoxy sulfate, alkyl sulfonate, alkyl alkoxycarb Carboxylates, alkyl alkoxylated sulfates, monoalkyl (ether) phosphates, dialkyl (ether) phosphates, sarcosinates, sulfosuccinates, isethionates, taurates, ammonium lauryl sulfate, ammonium laurate sulfate, triethylamine Lauryl sulfate, triethylamine laureate sulfate, triethanolamine lauryl sulfate, triethanolamine laureate sulfate, monoethanolamine lauryl sulfate, monoethanolamine laureate sulfate, diethanolamine lauryl sulfate, diethanolamine laurate Let's sulfate, lauric monoglyco Ceride sodium sulfate, sodium lauryl sulfate, sodium lauryl sulfate, potassium lauryl sulfate, potassium laurate sulfate, sodium lauryl phosphate, sodium tridecyl phosphate, sodium behenyl phosphate, sodium laurate-2 phosphate, sodium cetate- 3 Phosphate, Sodium Tridecet-4 Phosphate, Sodium Dilauryl Phosphate, Sodium Ditridecyl Phosphate, Sodium Ditridecet-6 Phosphate, Sodium Lauroyl Sarcosinate, Lauroyl Sarcozin, Cocoyl Sarcozin, Ammonium Cosyl sulfate, sodium cosyl sulfate, sodium tridecet sulfate, sodium tridecyl sulfate, ammonium tridecet sulfate, ammonium tridecyl sulfate, sodium cocoyl isethionate, disodium laureth sulfosuccinate, sodium methyl oleoyl tau Latex, sodium laurate carboxylate, sodium At least one anionic selected from the group consisting of deceased carboxylate, sodium lauryl sulfate, potassium kosyl sulfate, potassium lauryl sulfate, monoethanolamine kosyl sulfate, sodium tridecyl benzene sulfonate and sodium dodecyl benzene sulfonate A method that is a surfactant. The method of claim 1 wherein the anionic surfactant is added at 0.002-50% by weight of the total solution. The apparatus of claim 1, wherein the EASP device comprises: an injector capable of injecting a precursor solution; A substrate support capable of supporting a substrate and charging the substrate; And a power generator for providing a potential difference between the injector and the substrate support. The method of claim 1 wherein the acceleration voltage of the EASP device is between 6 and 15 kV. The method of claim 1, wherein the substrate is maintained at 100 to 250 ° C. by a thermostat. The method of claim 1, wherein the removal of the surfactant is performed by impregnating the carbon nanotube thin film with a mixture of water and an alcohol-based solution, followed by washing with distilled water. A three-dimensional porous carbon nanotube thin film having a mixed pupil structure of a macro-sized pupil and a meso-sized pupil prepared by the method of any one of claims 1 to 15.

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