KR101083060B1 - Method for producing carbon composite nano fiber with photocatalytic activity, carbon composite nano fiber with photocatalytic activity produced by the same method, filters comprising the carbon nano fiber and TiO2,SiO2 sol solutions used for thermo stable photo catalyst - Google Patents

Abstract

 The present invention relates to carbon nanofibers, and more specifically, to a method for producing a composite carbon nanofiber having a photocatalytic activity, a composite carbon nanofiber prepared by the manufacturing method thereof, a filter including the composite carbon nanofiber, and the composite carbon nanofiber. A thermostable photocatalyst sol solution used in the manufacture of fibers.

Electrospinning, photocatalyst, photoactive, TiO2, SiO2, sol-gel, dip coating, composite carbon nanofiber

Description

A method for producing a composite carbon nanofiber having a photocatalytic activity, a composite carbon nanofiber having a photocatalytic activity produced by the method, a filter comprising the composite carbon nanofiber, and a thermally stable photocatalyst sol solution used in the manufacturing method. carbon composite nano fiber with photocatalytic activity, carbon composite nano fiber with photocatalytic activity produced by the same method, filters comprising the carbon nano fiber and TiO2, SiO2 sol solutions used for thermo stable photo catalyst}

The present invention relates to carbon nanofibers, and more specifically, to a method for producing a composite carbon nanofiber having a photocatalytic activity, a composite carbon nanofiber prepared by the manufacturing method thereof, a filter including the composite carbon nanofiber, and the composite carbon nanofiber. A thermostable photocatalyst sol solution used in the manufacture of fibers.

Generally, sources of environmental pollution present in water can be largely classified into suspended matter, dissolved organic matter and dissolved inorganic matter. The suspended solids with a high specific gravity among the suspended solids can be removed by sedimentation method. In the case of suspended solids which are relatively hard to settle, they can be removed by floating flotation using saturated air bubbles. However, advances in industrialization have resulted in the release of large quantities of biologically degradable substances that are difficult for microorganisms to degrade. These hardly decomposable materials are rarely removed by the conventional activated sludge process using mixed suspended microorganisms, which causes serious environmental pollution.

Photocatalysts are "materials that do not change themselves when irradiated with light, but catalyze chemical reactions." It refers to a substance that advances the catalytic reaction using light as an energy source, and a semiconductor metal oxide or a sulfur compound is used as the photocatalyst. Such photocatalysts have been known to decompose various biologically hardly decomposable substances that existing microorganisms cannot remove. Examples of such photocatalysts include ZnO, WO ₃ , SnO ₂ , ZrO ₂ , TiO ₂ , and CdS. There is this.

Among them, titanium dioxide (TiO ₂ ) having an anatase crystal structure is particularly used. The energy required to cause the photoexcitation reaction is 387.5 nm, and sufficient energy can be received from sunlight. This is because it is excellent in physical properties such as harmless to the human body.

That is, in a semiconductor, when energy of a certain region is applied, electrons are excited from the valence band to the conduction band. That is, electrons [e-, electrons] are formed in the conduction band and holes [h +, electron holes] are formed in the valence band. Holes (h +) react with water to produce hydroxyl radicals (.OH), and in the opposite reduction reaction, oxygen is reduced in air, producing superoxide anions (O ₂ ⁻ ) and two active oxygen species. .

In particular, since radicals have high oxidation and reduction potentials, they are excellent for NO _x , SO _x , volatile organic compounds (VOCs) and various odor purification, BOD, color and hardly degradable contaminants of livestock wastewater, sewage, factory wastewater, environment In addition to removing hormones, it can sterilize over 99% of pathogens and bacteria such as Escherichia coli, Staphylococcus aureus, and O-157.

As described above, titanium dioxide powder having anatase crystal structure has excellent photocatalytic properties and is relatively easy to synthesize, and many studies on this have been conducted (US Pat. No. 6,022,824). However, such titanium dioxide powder has a problem that the size of the titanium dioxide powder is about 0.1 μm or less, which is very small, so that a membrane such as a membrane may be used to recover the titanium dioxide powder when it is manufactured with a continuous flow type water treatment reactor (US Pat. No. 5,462,674). In addition, the titanium dioxide powder accumulates on the separation membrane surface, resulting in shortening the life of the membrane, and consequently has a problem of lowering the removal efficiency of the entire water treatment reactor system.

In addition, in the case of forming a photocatalyst system by dispersing a very small powdered titanium dioxide, it is very difficult for the dispersed titanium dioxide powder to absorb light and irradiate the light uniformly throughout the water treatment reactor. Made difficult [US Pat. No. 5,275,741].

In addition, US Patent Nos. 5,591,380, 4,176,089 and the like have a problem in that when the two types of sol are uniformly dispersed in the support, the stability of the sol is lowered and is easily gelled to thicken the coating film or the process is complex.

In addition, Korean Patent Laid-Open Publication Nos. 2001-0084574 and 10-2004-0003759 propose a method for producing a titanium dioxide photocatalyst supported or supported on silica gel. In this case, in order to ensure stability as a catalyst, it was used after calcining heat treatment at 400 ~ 600 ℃. These photocatalysts are phase-changed into a rutile structure at a high temperature, and the efficiency of the photocatalyst is drastically reduced.

Carbon nanofibers, on the other hand, are a new kind of activated carbon having a nanographite structure and are a new type of carbon material capable of mass production, having a large specific surface area and excellent conductivity. Compared to activated carbon, which is a kind of adsorbent, carbon nanofibers have a large specific surface area, shallow pore depth, and micropores of 1-2 nm size. It can be used for effective adsorption, decolorization, water treatment agent, deodorant, moisture absorbent and the like. However, carbon nanofibers use only the adsorptivity of the porous structure, and when the adsorption is completed, the purification ability is sharply reduced.

The present inventors have a photocatalytic property using carbon nanofibers and a photocatalyst material and at the same time have the inherent properties of carbon nanofibers, and a composite carbon nanofiber manufacturing method having a photocatalytic activity having a superior purification function and a composite carbon manufactured by the method Nanofibers were developed to complete the present invention.

Accordingly, an object of the present invention is a method for producing a composite carbon nanofiber having a photocatalytic activity of simultaneously adsorbing and decomposing organic substances by simultaneously retaining the inherent adsorption capacity of carbon nanofibers and the decomposition ability of the photocatalyst, and composite carbon nanoparticles prepared by the method It is to provide a filter comprising a fiber and the composite carbon nanofibers.

Another object of the present invention is a composite carbon nanofiber manufacturing method having a photocatalytic activity which shows a high photoactivity compared to the existing photocatalyst, and has a high photocatalytic activity for color treatment of high concentration dyeing waste water due to excellent photolysis ability of a high concentration dye, It is to provide a filter comprising a composite carbon nanofibers and the composite carbon nanofibers prepared by.

Still another object of the present invention is a method for producing a composite carbon nanofiber having a photocatalytic activity having a photocatalytic activity of adsorbing and decomposing harmful gases as well as photocatalytic reaction of a general organic compound even at a high temperature, and a composite carbon nanofiber prepared by the method. It is to provide a filter comprising a composite carbon nanofibers.

Still another object of the present invention is a method for producing a composite carbon nanofiber having a photocatalytic activity which is extremely suitable to be widely used in an air purifier filter, an automobile exhaust gas purification filter, and a water purification filter, and a composite carbon nanofiber manufactured by the manufacturing method thereof. And to provide a filter comprising the composite carbon nanofibers.

It is still another object of the present invention to provide a thermally stable photocatalyst sol solution having a composition in which the crystal structure of titanium dioxide maintains an anatase structure having thermal stability even though heat is applied to titanium dioxide used as a photocatalyst to have high optical activity. To provide.

The objects of the present invention are not limited to the above-mentioned objects, and other objects that are not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, the present invention comprises the steps of stabilizing the carbon nanofiber precursor obtained by electrospinning the spinning solution in which the carbon fiber precursor material is dissolved at 200 to 350 ℃ to obtain a flame-resistant fiber; Preparing a photocatalyst sol solution; Coating the chlorinated fiber by dipping the photocatalyst sol solution; And it provides a composite carbon nanofiber manufacturing method having a photocatalytic activity comprising the step of carbonizing the coated flame resistant fiber after drying.

In a preferred embodiment, the photocatalyst is any one selected from the group of ZnO, WO ₃ , SnO ₂ , ZrO ₂ , TiO ₂ , CdS.

In a preferred embodiment, in preparing the photocatalyst sol solution, SiO ₂ is further added to prepare a photocatalyst sol solution.

In a preferred embodiment, the photocatalyst sol solution to which SiO ₂ is further added is obtained by preparing a SiO ₂ sol solution and then stirring while adding the photocatalyst.

In a preferred embodiment, the carbonization step is carried out by heating to 900 ° C.

In a preferred embodiment, the carbon nanofiber precursor material is any one selected from the group consisting of polyacrylo nitrile (PAN), polyimide, polybenzimidazole (PBI), and pitch. .

In another aspect, the present invention provides a carbon nanofiber having a photocatalytic activity prepared by the method of any one of claims 1 to 6, wherein the included photocatalyst is titanium dioxide, the composite carbon nanofibers having a photocatalytic activity. do.

In a preferred embodiment, the crystal structure of the titanium dioxide has anatase structure of 50% or more.

In a preferred embodiment, the specific surface area of the composite carbon nanofibers having the photocatalytic activity is 254 m ² / g.

The present invention also provides a filter having a stable photocatalytic activity even at high temperature, including the composite carbon nanofibers having the photocatalytic activity of claim 7.

In addition, the present invention is a photocatalyst coated on the surface of the material to give the photocatalytic activity is further included in a state in which SiO ₂ is dispersed in a sol solution in which titanium dioxide is dispersed is more than 750 ℃ in titanium dioxide coated on the surface of the material Provided is a thermally stable photocatalyst sol solution characterized in that the crystal structure of the titanium dioxide is inhibited from phase transition from anatase to rutile crystal structure even when heat is applied.

In a preferred embodiment, the thermally stable photocatalyst sol solution is tetraethyl orthosilicate (TEOS), titanium isopropoxide (TiP), ethanol (Ethyl alcohol) having a purity of 98% or more. ), Water and 0.05 N HCl, the TEOS and TiP is in a dispersed state.

In a preferred embodiment, the thermally stable photocatalyst sol solution is obtained by mixing TEOS, water, and 0.05 N HCl in the ethanol to prepare a silica sol solution, followed by stirring while adding TiP.

The present invention has the following excellent effects.

The composite carbon nanofibers prepared by the method of manufacturing the composite carbon nanofiber of the present invention and the filter including the composite carbon nanofibers have the adsorption capacity and the photocatalytic decomposition ability of carbon nanofibers at the same time to decompose organic substances simultaneously with adsorption. It has excellent photocatalytic activity.

The composite carbon nanofibers produced by the composite carbon nanofiber manufacturing method of the present invention and the filter including the composite carbon nanofibers show higher photoactivity than conventional photocatalysts, and have excellent photodegradation ability of high-density dyes for color treatment of highly concentrated dye wastewater. High purification efficiency can be obtained.

The composite carbon nanofibers prepared by the composite carbon nanofiber manufacturing method of the present invention and the filter including the composite carbon nanofibers have excellent photocatalytic activity having the adsorption and decomposition function of harmful gases as well as photodegradation reaction of general organic compounds even at high temperature. Has

The composite carbon nanofibers produced by the composite carbon nanofiber manufacturing method of the present invention and the filter including the composite carbon nanofibers are excellent photocatalysts that are extremely suitable for being widely used in air purifier filters, automobile exhaust gas purification filters, and water purification filters. Have activity.

The thermally stable photocatalyst sol solution that can be used in the composite carbon nanofiber manufacturing method of the present invention is an anatase structure in which the crystal structure of titanium dioxide has thermal stability even when heat of 750 ° C. or more is applied to titanium dioxide used as a photocatalyst to impart photocatalytic activity. It has a composition to maintain the high light activity.

The terms used in the present invention were selected as general terms as widely used as possible, but in some cases, the terms arbitrarily selected by the applicant are included. In this case, the meanings described or used in the detailed description of the present invention are considered, rather than simply the names of the terms. The meaning should be grasped.

First, the composite carbon nanofiber manufacturing method having the photocatalytic activity of the present invention does not coat the photocatalyst on the finished product as is generally known, but rather the photocatalyst is coated in the carbon nanofiber manufacturing process, that is, the photocatalyst is immersed in the flame resistant fiber. After the carbonization process to warm up to 900 ℃ to finally produce a composite carbon nanofibers having a photocatalytic activity.

Therefore, according to the manufacturing method of the present invention, the photocatalyst constitutes a part of the carbon nanofibers, so that the photocatalyst naturally forms a fixed phase and the organic catalyst to which the photocatalyst can act can be easily adsorbed by the adsorption capacity of the carbon nanofibers. The activity can be significantly improved, making it extremely suitable for use as a filter.

However, the composite carbon nanofiber manufacturing method of the present invention further provides a technical configuration that can lower or maintain or improve the degree of degradation of the photocatalytic activity even at a carbonization process of 900 ° C. when the photocatalyst used is not thermally stable. It is preferable.

For example, titanium dioxide (TiO ₂ ), which is most commonly used as a general photocatalyst, has two crystal structures, rutile and anatase. Due to the structural difference between the crystals, anatase (3.2 eV) It has a bandgap slightly larger than rutile (3.0 eV), which results in fast electron-hole recombination reactions on the rutile surface, with fewer rutiles than anatase in the number of reactants attached to the surface and the amount of hydroxyl groups on the surface Because of this, the light efficiency of anatase is generally higher than rutile, so it is desirable to have an anatase structure even at high temperatures.

However, titanium dioxide begins to phase change its crystal structure from anatase to rutile crystal structure at 750 ° C. At firing temperatures above 900 ° C, meta-stable anatase peaks are not observed at all in the X-ray diffractometer (XRD). Only in rutile peaks are measured.

Accordingly, the present invention provides a thermally stable photocatalyst sol solution that can be used in a method for producing a composite carbon nanofiber having a photocatalytic activity, that is, to maintain the photocatalytic activity of titanium dioxide even at a temperature of more than 900 ℃.

Hereinafter, the technical structure of the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals designate like elements throughout the specification.

1 is a flow chart briefly showing each process of the composite carbon nanofiber manufacturing method having a photocatalytic activity according to an embodiment of the present invention, Figure 2a is a photocatalyst coated electron of the composite carbon nanofibers by the method of Figure 1 2B is a graph of an energy dispersive X-ray spectrometer (EDX), FIG. 3 is a graph of X-ray diffraction analysis (XRD) of TiO ₂ / SiO ₂ coated carbon nanofibers, and FIG. 4 is TiO ₂ a graph of X-ray diffraction analysis (XRD) of the coated carbon nano-fiber, 5 is a TiO ₂ / SiO ₂ coating of carbon and FT-IR graph of a nano fiber, and Fig. 6 is a TiO ₂ / SiO ₂ coating the composite carbon nano The concentration of Methylene blue solution was determined by irradiating UV rays to fibers [(TiO ₂ / SiO ₂ ) / CNFs], TiO ₂ coated carbon nanofibers [TiO ₂ / CNFs] and composite carbon nanofibers [CNFs]. This is a graph analyzed by VU-Vis spectrophotometer.

Example 1

The composite carbon nanofibers having the photocatalytic activity were prepared by performing the process shown in FIG. 1 as follows.

1. Preparation of PAN Chlorinated Fiber

PAN for carbon fiber was dissolved in dimethyformamide (DMF) to prepare a spinning solution. This PAN solution was prepared using a non-woven web composed of nanofibers using an electrospinning method. At this time, the electrospinning apparatus applied an applied voltage of 30 kV to the nozzle and the collector, respectively, and the distance between the spinneret and the collector was varied as needed about 10 to 30 cm. The PAN spinning fiber obtained by electrospinning was supplied with compressed air at a flow rate of 5-20 mL per minute using a hot air circulating fan, and stabilized by maintaining it at 200-300 ° C. for 1 hour at a temperature rising rate of 1 ° C. per minute. Got.

2. Preparation of Thermostable Photocatalyst Sol Solution

The TiO ₂ / SiO ₂ sol solution, a thermally stable photocatalyst sol solution, contains tetraethyl orthosilicate (TEOS), Titanium (IV) isopropoxide TiP, Ethanol (Ethyl alcohol) was purchased and used as it is. First, TEOS, water, and 0.05 N HCl were mixed in ethanol to prepare a silica sol solution, followed by vigorous stirring while slowly adding TiP to complete the TiO ₂ / SiO ₂ sol solution.

3. Dip coating of PAN flame resistant fiber

PAN flame-resistant fiber was immersed in TiO ₂ / SiO ₂ sol solution for 2 hours, dried in air, and carbonized by heating to 900 ° C. at a heating rate of 5 ° C. per minute (ie, TiO ₂ / SiO ₂ coated carbon nanofibers) was prepared.

Example 2

Except that TEOS was not added to the photocatalyst sol solution, TiO ₂ -coated composite carbon nanofibers were prepared in the same manner as in Example.

Experimental Example 1

In order to confirm the presence of the photocatalyst in the composite carbon nanofibers having the photocatalytic activity prepared in Example 1, it was observed by electron microscope in FIG. 2a, and a graph of an energy dispersive X-ray spectrometer (EDX) is shown in FIG. 2b. .

From the electron microscope photograph of FIG. 2A, it was confirmed that TiO _{2, which} is an ultrafine photocatalyst particle having a size of 20-40 nm, was uniformly distributed on the surface of the carbon nanofibers.

In addition, elements of C, Ti, and Si of TiO ₂ / SiO ₂ coated carbon nanofibers, that is, composite carbon nanofibers having photocatalytic activity were identified from FIG. 2B, which is a graph of an energy dispersive X-ray spectrometer (EDX).

Experimental Example 2

Example 1 TiO ₂ / SiO ₂ composite coating of carbon nanofiber as in Example 2 X- ray diffraction whether maintaining the photocatalytic TiO ₂ the photocatalytic activity include the production of TiO ₂ coated with the composite manufactured from the carbon nanofiber The pattern was examined and the results are shown in Table 1, FIG. 3 and FIG. 4.

As shown in Table 1, when the silica was dispersed, that is, when the thermally stable photocatalyst sol solution was used, the phase transition of TiO ₂ was suppressed even at a high carbonization temperature of 900 ° C, resulting in a mixture of 8: 2 crystal structures of anatase and rutile. The crystal size of, anatase was 20 nm as calculated by the Scherrer equation. In addition, the carbon nanofibers coated with the photocatalyst at a high temperature had a specific surface area of 254 m ² / g.

However, when only TiO ₂ was coated on the carbon nanofibers, the phase transition of rutile was promoted by the high temperature, which greatly increased the ratio of rutile and increased the particle size of the catalyst.

^a specific surface area of carbon nanofibers

^b CNF-Carbon Nano Fiber

In addition, from Fig. 3, which is an X-ray diffraction pattern of TiO ₂ / SiO ₂ coated carbon nanofibers, it was confirmed that the TiO ₂ particles, which are photocatalysts, were mixed with 8: 2 in the form of anatase and rutile. From these results, unlike the conventional photocatalyst, which appears in the form of rutiles having low activity at high temperatures, the thermally stable photocatalyst sol solution of the present invention suppresses the phase transition of TiO ₂ to obtain a photocatalyst that maintains the crystal structure of anatase. I could see that.

Experimental Example 3

FT-IR was performed on the TiO ₂ / SiO ₂ coated carbon nanofibers obtained in Example 1, and the results are shown in FIG. 5.

5 shows a specific peak of Ti-O-Si at 930 cm ^-1 , which shows that silica (SiO ₂ ) is dispersed in TiO ₂ to prevent phase transition to rutile crystals to maintain the structure of anatase.

In other words, it was found that SiO ₂ prevents TiO ₂ from agglomerating at high temperature by disturbing the movement of TiO ₂ particles and molecules, thereby increasing the particle size and inhibiting phase transition from anatase to rutile.

Experimental Example 4

The photoactive reaction of TiO ₂ / SiO ₂ coated carbon nanofibers and TiO ₂ coated carbon nanofibers was performed using methylene blue dye as follows, and the results are shown in FIG. 6.

First, a solution of methylene blue (MB) dye was prepared at a concentration of 10 ppm. 100 mL of this solution and 0.1 g of TiO ₂ / SiO ₂ coated carbon nanofibers or TiO ₂ coated carbon nanofibers were placed in a beaker and irradiated with UV (8 W, 365 nm, Sankyo Denki) to observe dye degradation performance. It was. After the reaction, 3 mL of the reaction solution was collected at regular time intervals to confirm the change in concentration of MB, and the solution was separated using a 0.45 μm (Millipore millex filter) filtration membrane to obtain a pure solution containing no TiO ₂ particles. . The concentration of MB according to reaction time was measured by UV-Vis spectroscopy.

As shown in FIG. 6, in the case of TiO ₂ coated carbon nanofibers [TiO ₂ / CNFs], the rutile fraction was increased so that the catalytic activity was greatly reduced, but the decomposition efficiency was superior to CNFs. In addition, it was found that the composite carbon nanofibers [(TiO ₂ / SiO ₂ ) / CNFs] retained the crystal structure of anatase even at high firing temperature, so that the dye was almost decomposed in 30 minutes.

In the above experimental examples and examples, TiO ₂ was used as the photocatalyst, but similar results can be obtained using other photocatalyst materials ZnO, WO ₃ , SnO ₂ , ZrO ₂ , and CdS. Do not exclude that. In addition, in the case of the carbon nanofiber precursor material, any one selected from the group consisting of polyimide, polybenzimidazole (PBI), and pitch in addition to polyacrylonitrile (PAN) may be used. have.

As described above, when the carbon nanofibers having the photocatalytic activity produced by the carbon nanofibers having the photocatalytic activity of the present invention are titanium dioxide, the crystal structure of the titanium dioxide has a specific surface area of 50% or more as the anatase structure. Since it is more than 254 m ² / g, it has the function of adsorption and decomposition of harmful gases as well as photodegradation reaction of general organic compounds even at high temperature. Therefore, the filter including the composite carbon nanofibers can be widely used in filters for air cleaners, exhaust filters for automobiles, etc., and can be widely used as water purification filters because it can decompose wastewater treatment, pollutants and pigments in water. Can be.

In addition, the thermally stable photocatalyst sol solution of the present invention is capable of maintaining the crystal structure of the titanium dioxide in the anatase structure even when heat of 750 ° C. or more is applied to the titanium dioxide dispersed in the solution, thereby providing a composite carbon nanofiber having the photocatalytic activity of the present invention. In addition to the manufacturing method, it can be variously applied to the field to have a photocatalytic activity at a high temperature using another material.

As described above, the present invention has been illustrated and described with reference to preferred embodiments, but is not limited to the above-described embodiments, and is provided to those skilled in the art without departing from the spirit of the present invention. Various changes and modifications will be possible.

1 is a flow chart briefly showing each process of the composite carbon nanofiber manufacturing method having a photocatalytic activity according to an embodiment of the present invention;

Figure 2a is an electron micrograph of a composite carbon nanofiber coated with a photocatalyst by the method of Figure 1, Figure 2b is a graph of an energy dispersive X-ray spectrometer (EDX),

3 is a graph of X-ray diffraction analysis (XRD) of TiO ₂ / SiO ₂ coated carbon nanofibers,

4 is a graph of X-ray diffraction analysis (XRD) of TiO ₂ coated carbon nanofibers,

5 is an FT-IR graph of TiO ₂ / SiO ₂ coated composite carbon nanofibers,

6 shows ultraviolet rays in TiO ₂ / SiO ₂ coated carbon nanofibers [(TiO ₂ / SiO ₂ ) / CNFs], TiO ₂ coated carbon nanofibers [TiO ₂ / CNFs] and carbon nanofibers [CNFs]. When irradiated, the concentration of Methylene blue solution was analyzed by VU-Vis spectrophotometer according to the irradiation time.

Claims (13)

Stabilizing the carbon nanofiber precursor obtained by electrospinning the spinning solution in which the carbon fiber precursor material is dissolved at 200 to 350 ° C. to obtain flame-resistant fibers; Preparing a photocatalyst sol solution; Coating the chlorinated fiber by dipping the photocatalyst sol solution; And Composite carbon nanofiber manufacturing method having a photocatalytic activity comprising the step of carbonizing the coated flame resistant fiber after drying. The method of claim 1, The photocatalyst is a composite carbon nanofiber manufacturing method having a photocatalytic activity, characterized in that any one selected from the group of ZnO, WO ₃ , SnO ₂ , ZrO ₂ , TiO ₂ , CdS. The method of claim 1, The method for preparing a composite carbon nanofiber having photocatalytic activity, characterized in that preparing a photocatalyst sol solution by further adding SiO ₂ in preparing the photocatalyst sol solution. The method of claim 3, wherein The method of manufacturing a composite carbon nanofiber having photocatalytic activity, characterized in that the photocatalyst sol solution to which SiO ₂ is further added is obtained by preparing a SiO ₂ sol solution and then stirring while adding the photocatalyst. The method of claim 1, The carbonizing step is a composite carbon nanofiber manufacturing method having a photocatalytic activity, characterized in that performed by heating up to 900 ℃. The method of claim 1, The carbon nanofiber precursor material is any one selected from the group consisting of polyacrylo nitrile (PAN), polyimide, polybenzimidazole (PBI), and pitch. Composite carbon nanofiber manufacturing method having activity. A carbon nanofiber having a photocatalytic activity prepared by the method of any one of claims 1 to 6, wherein the included photocatalyst is titanium dioxide. The method of claim 7, wherein The crystal structure of the titanium dioxide composite carbon nanofibers having a photocatalytic activity, characterized in that the anatase structure is 50% or more. The method of claim 7, wherein A composite carbon nanofiber having a photocatalytic activity, characterized in that the specific surface area of the carbon nanofibers having the photocatalytic activity is 254 m ² / g or more. A composite carbon nanofiber having a photocatalytic activity of claim 7 and a filter having a stable photocatalytic activity even at high temperatures. delete delete delete

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