JP2002028494A - Photocatalyst carrier, and producing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalyst carrier which is an excellent environment purifying material usable as a wall material and an air filter in a super-clean closed space and a closed conveyance space for semiconductor, clean rooms of various kinds of uses, an office building and an ordinary house, and a producing method thereof. SOLUTION: This photocatalyst carrier is constituted by covering the surface of inorganic fiber cloth with a photocatalyst layer and features that fluorine is incorporated in the photocatalyst layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a photocatalyst carrier and a method for producing the same. More specifically, it is used as an ultra-clean sealed space for semiconductors and a sealed transfer space, as a wall material and air filter in various types of clean rooms, office buildings and general homes, to provide excellent functions for air purification in indoor spaces. The present invention relates to a photocatalyst-supporting fiber cloth to be exhibited and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, in the field of semiconductors, with an increase in the density of devices, a decrease in yield due to adsorption of a trace amount of organic gas in a clean room onto a substrate has become a problem. Also, in general houses, allergies due to various plasticizers, such as formaldehyde and acetaldehyde, which are present in a small amount indoors, are becoming more serious.

[0003] Since the photocatalyst has a strong oxidizing power for organic substances, it can decompose various organic gases existing in a room, and thus has the potential to become a key material for solving the above problems. I have. When an organic gas is decomposed by using a photocatalyst, its concentration is extremely low. Therefore, it is important to improve the intrinsic activity of the photocatalyst and at the same time increase its surface area.

Heretofore, attempts have been made to support a photocatalyst on shoji paper or a support made of glass fiber cloth for the purpose of decomposing a dilute organic gas (for example, JP-A-1-139139). However, although shoji paper has the merit of having a large surface area, it is inevitable to be deteriorated because it is an organic substance itself, and its use is limited to a narrow range because it may lead to a new pollution source.
Also, by directly supporting the photocatalyst on a glass fiber cloth,
High photocatalytic activity cannot be obtained. The reason is that the alkali component diffused from the glass in the process of fixing the photocatalyst to the glass fiber lowers the crystallinity of the photocatalyst.

[0005]

SUMMARY OF THE INVENTION The present invention relates to an ultra-clean sealed space for semiconductors, a sealed transfer space, a clean room for various uses, an office building, a wall material in an ordinary house, and an air filter for removing harmful organic gas. An object of the present invention is to provide a photocatalyst carrier having high photocatalytic activity, which is an excellent environmental purification material that can be efficiently decomposed and removed, and a method for producing the same.

[0006]

According to the present invention, there is provided a photocatalyst carrier having a photocatalyst layer coated on the surface of an inorganic fiber cloth, wherein the photocatalyst layer contains fluorine.

In the present invention, the photocatalytic activity is significantly improved by including fluorine in the photocatalyst layer coated on the surface of the inorganic fiber cloth. If the doping amount of fluorine is too small, the effect of improving the photocatalytic activity is small, so that fluorine is preferably contained in the photocatalyst layer in an amount of 0.02 to 1.0% by weight. As a method of including fluorine in the photocatalyst layer, a fluorine compound may be directly added to the material for forming the photocatalyst layer, and a fluorine-containing layer may be previously provided between the surface of the inorganic fiber cloth and the photocatalyst layer. May be provided to diffuse fluorine from the fluorine-containing layer to the photocatalyst layer when the photocatalyst layer is fired. When glass fibers, particularly fibers having an alkali-containing glass composition, are used as the inorganic fiber cloth substrate, this layer is made of alkali metal by forming a fluorine-containing layer of silicon oxide or other metal oxide as the fluorine-containing layer. It also acts as a blocking layer and can prevent the alkali metal ions, for example, Na ions in the glass fibers from diffusing and moving into the photocatalyst layer to impair the photocatalytic activity of the photocatalyst layer.

[0008] The material of the photocatalyst is not particularly limited.
An oxide semiconductor such as titanium oxide, zinc oxide, tungsten oxide, or iron oxide can be used. Among them, titanium oxide having high activity and excellent physicochemical stability can be preferably used.

The photocatalytic activity strongly depends on the thickness of the photocatalytic film. If the film thickness is too small, light cannot be sufficiently absorbed. If the film thickness is too large, the photocarriers generated in the film cannot diffuse to the outer surface of the film, so that the catalytic activity decreases. Although the optimum film thickness varies depending on the use conditions, good photocatalytic activity can be exhibited in the range of 5 nm to 2 μm, more preferably in the range of 20 nm to 1 μm, and still more preferably in the range of 50 to 200 nm.

[0010] The photocatalyst layer is formed by a conventional thin film manufacturing method, that is, a vacuum deposition method, a chemical vapor deposition (CVD) method, a sol-gel method,
Titanium oxide (Ti
O ₂ ), ZnO, ZnS, WO ₃ , Fe ₂ O ₃ , GaAs
P, CdSe, GaAs, CdS, SrTiO ₃ , Ga
A thin film of P, In ₂ O ₃ , MoO ₂ , TiO ₂ -Pt-RuO ₂ alloy or the like is produced. The TiO ₂ film most widely used at present can form a titanium oxide crystal thin film by using, for example, a vacuum deposition method. When a fluorine-containing layer is provided in advance between the inorganic fiber cloth base material surface and the photocatalyst layer, heat treatment is performed, preferably by heating the titanium oxide thin film at 450 to 550 ° C. for 10 minutes to 2 hours. Fluorine diffuses from the fluorine-containing layer, which is the undercoat layer, into the titanium oxide thin film, so that the photocatalytic activity is improved.
When a chemical vapor deposition (CVD) method or a sol-gel method is used, heat treatment for crystallizing an amorphous titanium oxide thin film formed first is required. The crystallization heat treatment is usually performed at 450 to 550 ° C. for 10 minutes to 2 hours. When a fluorine-containing layer as an undercoat layer is provided, the above-mentioned diffusion of fluorine from the fluorine-containing layer naturally occurs during the crystallization heat treatment. Therefore, in this case, a special treatment for diffusing fluorine may not be performed.

The fluorine-containing layer is not particularly limited, but an inexpensive fluorine-containing silica film can be suitably used. Further, the production of the fluorine-containing silica film is not particularly limited, but in order to completely cover each of the inorganic fibers constituting the cloth base material, hydrofluoric acid in which silica is in a supersaturated state is required. A liquid phase film forming method utilizing a precipitation reaction from a solution is most preferable.

By providing the fluorine-containing layer undercoat in the present invention, the fluorine contained in the undercoat diffuses into the titanium oxide film, and the film quality of the titanium oxide is improved. When the base material contains an alkali metal component, it can be an alkali barrier film for preventing the diffusion of alkali metal ions, for example, Na ions in the glass substrate, in addition to the improvement of the titanium oxide film quality.

Although the type of the fluorine-containing layer in the present invention is not limited, an oxide thin film such as a silica thin film, a zirconia thin film, or an alumina thin film is preferably used from the viewpoint of preventing diffusion of Na ions and other alkali metal ions. can do. The method of incorporating fluorine into the fluorine-containing layer, that is, the method of doping with fluorine depends on the method of forming the fluorine-containing layer. In particular, as described above, a method in which a substrate is immersed in an aqueous solution of hydrosilicofluoric acid containing silicon dioxide (silica) in supersaturation to deposit and grow a silicon dioxide film on the surface of the substrate (liquid phase deposition method). The silica thin film manufactured by the method described above can not only be formed at a low temperature, but also can be suitably used particularly for the present purpose because fluorine is naturally taken into the silica thin film. It is clear from the infrared absorption spectrum that the silica thin film is doped with fluorine mainly in the form of Si—F bonds. The fluorine doping amount in the fluorine-containing layer varies depending on the type of the fluorine-containing layer and the production method, but is preferably in the range of 0.1 to 20 atomic%, particularly 2 to 10 atomic% in order to improve the photocatalytic activity. is there. If the fluorine doping amount is less than 0.1 atomic%, the diffusion of fluorine from the alkali barrier film to the titanium oxide photocatalytic thin film becomes insufficient, and if it exceeds 20 atomic%, the alkali barrier performance also decreases. The thickness of the fluorine-containing layer may be set to an appropriate range in consideration of the ability of the material to prevent diffusion of Na ions and other alkali metal ions. In the case of a silica film, a film thickness of 30 nm or more is preferable, and from a viewpoint of cost-performance, 30 to 100 nm is particularly preferable.

[0014] Other methods for forming a fluorine-containing layer include:
Vacuum evaporation, sputtering, chemical vapor deposition (CVD)
A known method such as a method, a sol-gel method, or a spray baking method can be used.

A fluorine-containing layer is produced by a method of immersing a substrate in an aqueous solution of hydrosilicofluoric acid containing silicon dioxide in supersaturation to deposit and grow a silicon dioxide film on the surface of the substrate (liquid deposition method). In order to prepare a supersaturated state of silicon dioxide, a method of adding an aqueous solution of boric acid to a saturated solution of hydrosilicofluoric acid (Japanese Patent Publication No. 63-65620) may be used. Of adding a substance such as aluminum to a saturated solution of silicon dioxide (see JP-A-62-20)
876), a method of adding water to a saturated solution of hydrosilicofluoric acid in silicon dioxide (JP-A-3-237012), and the temperature dependence of the solubility of silicon dioxide in hydrosilicofluoric acid. A method of producing a supersaturated solution of silicon dioxide by utilizing, specifically, increasing the concentration of hydrosilicofluoric acid which has become a substantially saturated solution of silicon dioxide is known (Japanese Patent Application Laid-Open No. 61-28047). Patent Publication, JP-A-3-11
No. 2806), any of these methods may be used in the present invention.

In the above description, the case where the fluorine-containing layer is provided in advance between the surface of the inorganic fiber cloth substrate and the photocatalyst layer has been described. A fluorine compound such as trifluoroacetic acid may be contained in the compound solution for forming a metal oxide for a photocatalyst to be brought into contact with the compound. That is, for example, in the case of using a sol-gel method, a complex solution of a titanium alkoxide and a chelating agent, and a compound solution containing trifluoroacetic acid are coated on the surface of the base material, and heated by heating in an oxidizing atmosphere to contain fluorine. The resulting metal oxide photocatalyst film is obtained.

The mechanism of action of an oxide semiconductor photocatalyst such as titanium oxide is explained as follows. When light is applied to the photocatalyst, photocarriers (excited electron-hole pairs) generated by excitation of electrons in the valence band of the semiconductor that absorbed the light into the conduction band are generated from the inside of the photocatalyst to the surface. And reacts with adsorbed oxygen or oxide hydroxyl groups present in the photocatalytic surface layer. By this reaction, O ^2-
Active oxygen such as OH and OH is generated. These active oxygens oxidize and decompose organic substances adsorbed on the photocatalyst surface.

According to the present invention, the activity of the photocatalyst is improved by doping the photocatalyst film with fluorine. At present, it is not clear why the photocatalytic activity performance is improved by doping fluorine in the photocatalytic film. However, by doping the titanium oxide thin film with fluorine, the titanium oxide thin film, which originally had a high light transmittance and was colorless, is colored gray and has a low light transmittance, and in particular, the light absorption amount of the titanium oxide increases. Therefore, it is presumed that the use efficiency of light is increased.

When a fluorine-containing layer is provided and a glass fiber having an alkali metal component, for example, a glass fiber having a soda-lime silicate glass composition is used as the inorganic fiber cloth base material, the fluorine-containing layer is formed as described above. In addition to the improvement of the photocatalytic activity, the performance deterioration of the titanium oxide thin film is suppressed by preventing the diffusion of Na from the base material. That is, in a conventional photocatalyst using an alkali-containing glass substrate, when Na ions in the substrate enter the titanium oxide film during the production process, the crystallinity of the film is inhibited, or the Na ions are excited electron-positive. It is considered that the performance of the photocarriers is degraded because the photocarriers are prevented from diffusing to the photocatalyst surface because the photocarriers function as recombination centers of the hole pairs and charge separation efficiency is reduced. According to the present invention,
Even when an alkali-containing glass base material is used, the alkali barrier film (fluorine-containing layer) prevents alkali metal ions in the base material from entering the titanium oxide film, improves the crystallinity of the film, and further enhances excitation. It is concluded that the absence of alkali metal ions acting as recombination centers for electron-hole pairs prevents the charge separation efficiency from decreasing, thereby preventing the photocatalytic activity from deteriorating.

An air filter for a clean room or an air purifier is one of the most important uses of the photocatalyst carrier of the present invention. In the air filter, it is necessary to form a photocatalytic thin film on each inorganic fiber constituting the nonwoven fabric or woven fabric so as to prevent clogging of the mesh. The inorganic fiber fabric may be selected from mesh sizes according to the intended use. For example, the fabric is made of inorganic fibers having an average diameter of 0.20 to 5 μm, and has a thickness of 0.1 to 2 mm and a passing wind speed of 3-50mm at 320cm / min
An inorganic fiber cloth, such as a nonwoven cloth, having a gas flow resistance represented by the pressure loss of H ₂ O is preferably used. As the material of the inorganic fiber, fibers such as soda-lime silicate glass, alkali-free silicate glass, silica glass, and alumina can be used, and a material that can transmit light, particularly ultraviolet light, is preferable. When used as a nonwoven fabric, it is preferable not to use a resin binder.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment 1] Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited to only such embodiments. The coating of the fluorine-containing silica film on the glass fiber non-woven fabric was performed as follows. As a nonwoven fabric substrate made of glass fiber, a glass fiber having an average diameter of 0.5 μm with a soda-lime silicate glass composition (containing about 13% by weight of an alkali metal oxide) was wet-processed without containing a resin binder to a thickness of about 0.1 mm. 5mm, weight per unit area is 200g / m ² , pressure loss is wind speed 3
Non-woven fabric of about 20 mmH ₂ O at 20 cm / min (dimensions: 10
cm × 10 cm).

3.9 moles of silica gel saturated and dissolved
Incubate 50 mL of L hydrosilicofluoric acid aqueous solution at 35 ° C.
50 mL of water at 35 ° C. was added to prepare an aqueous solution of hydrosilicofluoric acid containing 1.95 mol / L of silicon dioxide in supersaturation. The above glass fiber nonwoven fabric substrate was immersed in a bath of this aqueous solution maintained at 35 ° C., maintained for about 2 hours, and then pulled out of the bath to obtain a fluorine-containing silica film-coated glass fiber nonwoven fabric. Electron micrographs confirmed that each glass fiber constituting the nonwoven fabric (nonwoven fabric A) was uniformly coated with the silica film. The average thickness of the silica film is about 40
nm. It was confirmed that the silica film contained 0.5% by weight of fluorine.

Next, a method of coating a fluorine-doped titanium oxide thin film by a sol-gel method will be described. 85.6
g (0.3 mol) of titanium tetraisopropoxide (T
60.3 g of i (OiPr) ₄ )
(0.6 mol) of acetylacetone (AcAc) was gradually added dropwise using a burette and stirred for about 1 hour to obtain a stable Ti (AcAc) ₂ (OiPr) ₂ complex solution (mother liquor). On the other hand, a solution was prepared by dissolving 0.14 g of trifluoroacetic acid (TFA) in 34.8 mL of ethanol. After adding 15 mL of the mother liquor to this solution, the mixture was sufficiently stirred to obtain a uniform coating solution for fluorine-doped titanium oxide. 3. After immersing the nonwoven fabric A coated with the fluorine-containing silica film in a coating solution,
Coating was performed by pulling up at a speed of 6 cm / min. After leaving it to dry at room temperature for about 30 minutes,
By calcining for a minute, a nonwoven fabric made of a photocatalyst-supporting glass fiber was obtained (referred to as Sample A). The amount of titanium oxide carried on each nonwoven fabric was measured by a plasma emission analysis method.
When converted, the fiber surface of each nonwoven fabric was coated with a titanium oxide thin film having a thickness of about 650 nm.
As a result of analysis by X-ray diffraction, it was confirmed that the obtained titanium oxide thin film was an anatase type titanium oxide. Further, the titanium oxide thin film of Sample A contained a total of about 0.1% by weight of fluorine diffused and transferred from the fluorine-containing silica film and fluorine derived from trifluoroacetic acid in the titanium oxide coating solution. The pressure loss value of Sample A was about 25 mmH ₂ O at a wind speed of 320 cm / min, and the rise in the pressure loss value was small compared to the value of the untreated nonwoven fabric (about 20 mmH ₂ O).

Comparative Example 1 30 parts by weight of tetraethoxysilane, 200 parts by weight of 2-propanol, and 20 parts of ethanol
0 parts by weight, 2.5 parts by weight of normal nitric acid and 30 parts by weight of water were added, and the mixture was stirred at 60 ° C. for 2 hours.
After stirring and curing for a day, a sol solution for an alkali shielding film was obtained.

The glass fiber nonwoven fabric substrate used in Example 1 was immersed in the sol solution for an alkali shielding film,
The sol was applied by pulling up at a speed of / min. afterwards,
This was dried at room temperature for several minutes, and further heat-treated at 500 ° C. for 3 hours to obtain a nonwoven fabric B in which a silica thin film having a thickness of about 80 nm was formed on the surface of a glass fiber having an average diameter of 0.5 μm constituting the nonwoven fabric B. .

170.7 g of tetraisopropoxy titanium was added to 118.6 g of 2-ethoxyethanol and stirred at 60 ° C. for 3 hours to obtain a titanium oxide coating solution. The nonwoven fabric B coated with the silica film was immersed in the titanium oxide coating solution, and then applied by pulling up at a speed of 4.6 cm / min. After leaving it to dry at room temperature for about 30 minutes, it was baked at 500 ° C. for 30 minutes to obtain a nonwoven fabric made of glass fibers supporting a photocatalyst (sample B). The amount of titanium oxide carried on each nonwoven fabric was measured by plasma emission spectroscopy, and was 24.4% by weight based on the weight of the nonwoven fabric before coating with titanium oxide. The titanium oxide thin film of about 650 nm was covered. As a result of analysis by X-ray diffraction, it was confirmed that the obtained titanium oxide thin film was an anatase type titanium oxide.

Example 2 A nonwoven fabric made of a photocatalyst-supporting glass fiber was prepared in the same manner as in Example 1, except that the coating solution for fluorine-doped titanium oxide in Example 1 was replaced with the titanium oxide coating solution in Comparative Example 1. did. (Sample C)

Example 3 Instead of coating the fluorine-containing silica film by dipping the aqueous solution of hydrosilicofluoric acid in Example 1, coating the silica film with the sol solution for an alkali shielding film in Comparative Example 1 and drying the silica film. A nonwoven fabric made of glass fiber carrying a photocatalyst was produced in the same manner as in Example 1 except that the above was carried out.
(Sample D)

Example 4 As a fiber cloth substrate, 1.0 μm
m of the average diameter of the silica fibers to wet papermaking was thickness of about 0.5mm without containing a binder, the weight per unit area of 200 g / m ² silica fiber nonwoven fabric (dimensions: 10
cm × 10 cm).

Photocatalyst loading was carried out in the same manner as in Example 1 except that the above-mentioned silica fiber nonwoven fabric (untreated) was used instead of the glass fiber nonwoven fabric coated with a fluorine-containing silica film by immersion in an aqueous solution of hydrosilicofluoric acid in Example 1. A nonwoven fabric made of silica fiber was produced. (Sample E)

The evaluation of the photocatalytic activity was performed by quantifying the change in acetaldehyde concentration due to light irradiation on sample A in a closed space filled with acetaldehyde-containing air by gas chromatography. That is, about 50
Photocatalyst-supported glass fiber nonwoven fabric sample A and 250 in a closed container filled with 00 cc of acetaldehyde-containing air (initial concentration of acetaldehyde of about 240 ppm).
A high-pressure mercury lamp light source of W was installed so that ultraviolet light from the light source placed at a distance of 20 cm to the surface of the nonwoven fabric could be irradiated in the vertical direction, and the change in acetaldehyde concentration due to the elapsed time of light irradiation was measured. The greater the photocatalytic activity of the nonwoven fabric, the faster the acetaldehyde is oxidized and decomposed, and the more rapidly the acetaldehyde concentration in the air decreases. The irradiation time (half-life) was measured until the initial concentration of acetaldehyde in the closed space before the light irradiation started was reduced to about 120 nm, which is about a half of the initial concentration. The smaller the half-life is, the higher the decomposition rate of acetaldehyde by the photocatalyst is, and the higher the photocatalytic activity is. Table 1 shows the results of measuring the half-life time for the samples B to E in the same manner as described above.

In each of the samples, a monotonous decrease in the acetaldehyde concentration with the light irradiation time was observed.
The time for the acetaldehyde concentration to decrease to one half of the initial concentration (decay time) is about 330 minutes for sample B, about 60 minutes for sample A, and Examples 1 to 4 (samples A and 4). C to E) show that the decomposition rate of acetaldehyde is higher than that of Comparative Example 1 (sample B).

[0033]

[Table 1]

When air containing acetaldehyde was circulated through the nonwoven fabric made of photocatalyst-supporting glass fiber using a blower during light irradiation, the decomposition rate of acetaldehyde was further increased in sample A, and the half-life was 20 minutes. Was.

[0035]

As described above, it is clear that the photocatalyst carrier according to the present invention has an extremely excellent ability to decompose dilute harmful organic gases, and it is apparent that the photocatalyst carrier has an ultra-clean sealed space for semiconductors and a sealed transport space. It can be suitably used as a wall material and an air filter in clean rooms, office buildings and general houses for various uses.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B32B 5/02 B32B 9/00 A 9/00 D06M 13/50 D06M 11/77 B01D 53/36 G 13 / 50 D06M 11/16 (72) Inventor Akihiko Hattori No. 1 Konoike-jikaido, Itami-shi, Hyogo F-term in Nippon Sheet Glass Techno-Research Co., Ltd. 4D048 AA22 AB01 AB03 BA02X BA02Y BA07X BA07Y BA13X BA13Y BA14X BA14Y BA43X BA43Y BA50X BA50Y BB08 CC38 CC40 CD05 EA01 4F100 AA01A AA03A AA20C AA21B AA33A AA36B AA36C AA36H AG00A BA02 BA03 BA07 BA10A BA10B DG01A DG11A DG15A EC20B EH462 EH512 EH662 EJ422 EJ582 EJ822 JA20 JD01C JL08B JM02C YY00A YY00B YY00C 4G069 AA03 AA08 BA02A BA02B BA04A BA14A BA14B BA15A BA15B BA21C BA22A BA25C BA27A BA27B BA38 BA48A BB01A BB01B BB08B BC02A BC02B BC09A BC09B BC50A BC50B BD05A B D15A BD15B BE06A BE06B BE08A BE08C BE11B BE34A BE34B CA01 CA07 CA10 CA17 EA03X EA03Y EA08 EA10 EB15X EB15Y EC22Y FA02 FB13 FB23 FB30 FB39 FB68 FC07 FC08 4L031 AB01 AB34 BA09 DA00 AB073

Claims (23)

[Claims] 1. A photocatalyst carrier in which a photocatalyst layer is coated on the surface of an inorganic fiber cloth, wherein fluorine is contained in the photocatalyst layer. 2. The method according to claim 1, wherein said fluorine is contained in the photocatalyst layer in an amount of 0.02 to 0.02.
The photocatalyst carrier according to claim 1, which is contained in an amount of 1.0% by weight. 3. The photocatalyst carrier according to claim 1, wherein the fluorine in the photocatalyst layer is diffused and moved from a fluorine-containing layer provided between the surface of the inorganic fiber cloth and the photocatalyst layer. 4. The photocatalyst carrier according to claim 3, wherein said fluorine-containing layer has alkali barrier properties. 5. The photocatalyst carrier according to claim 3, wherein said fluorine-containing layer has a thickness of 20 to 200 nm. 6. The fluorine-containing layer according to claim 3, wherein said fluorine-containing layer is a fluorine-containing silica thin film deposited by immersing said inorganic fiber cloth in a hydrosilicofluoric acid aqueous solution containing silica in supersaturation for a predetermined time. A photocatalyst carrier according to any one of the above. 7. The photocatalyst carrier according to claim 1, wherein an alkali barrier layer is provided between the surface of the inorganic fiber cloth and the photocatalyst layer. 8. The method according to claim 1, wherein the alkali barrier layer has a thickness of 20 to 200 nm.
The photocatalyst carrier according to claim 7, having a thickness of: 9. The photocatalyst carrier according to claim 7, wherein the alkali barrier layer is made of silica. 10. The photocatalyst carrier according to claim 1, wherein the photocatalyst layer is made of titanium oxide. 11. The photocatalyst carrier according to claim 1, wherein the photocatalyst layer has a thickness of 20 nm to 1 μm. 12. The photocatalyst carrier according to claim 1, wherein the inorganic fiber cloth is a nonwoven fabric made of inorganic fibers. 13. The photocatalyst carrier according to claim 1, wherein said inorganic fiber cloth is made of glass fibers having a soda-lime silicate glass composition. 14. The fiber cloth is made of inorganic fibers having an average diameter of 0.20 to 5 μm, has a thickness of 0.1 to ₂ mm, and has a thickness of 3 to 50 mmH ₂ when the passing air velocity is 320 cm / min.
An airflow resistance represented by a pressure loss of O 2.
14. The photocatalyst carrier according to any one of 13. 15. A method for producing a photocatalyst carrier in which a compound solution capable of forming a metal oxide for a photocatalyst is brought into contact with an inorganic fiber cloth substrate to form a metal oxide photocatalyst film on the surface of the substrate. Before contacting the compound solution, the surface of the base material is coated with a fluorine-containing film in advance, and after the metal oxide photocatalyst film is formed, the base material is coated with fluorine in the fluorine-containing film. A method for producing a photocatalyst carrier, which comprises heating the oxide photocatalyst film to a temperature at which it can move into the oxide photocatalyst film. 16. The method according to claim 15, wherein the heating is performed at a temperature of 450 to 600 ° C. 17. The fluorine-containing film is deposited and coated by immersing the substrate in a hydrosilicofluoric acid aqueous solution containing silica in supersaturation for a predetermined time.
3. The method for producing a photocatalyst carrier according to item 1. 18. The fluorine-containing film according to claim 15, wherein said fluorine-containing film is a fluorine-containing silica film obtained by coating a solution containing a silicon alkoxide and a fluorine compound on the surface of said fiber cloth and heating in a oxidizing atmosphere. A method for producing the photocatalyst carrier according to the above. 19. The method according to claim 18, wherein the fluorine compound is trifluoroacetic acid. 20. The metal oxide photocatalyst film according to claim 15, wherein said compound solution contains a titanium alkoxide, and said metal oxide photocatalyst film is obtained by coating said solution on said substrate surface and heating in an oxidizing atmosphere. A method for producing the photocatalyst carrier according to any one of the above. 21. The method according to claim 20, wherein the compound solution contains a complex of a titanium alkoxide and a chelating agent. 22. A method for producing a photocatalyst carrier, wherein a compound solution capable of forming a metal oxide for a photocatalyst is brought into contact with the surface of an inorganic fiber cloth substrate to form a metal oxide photocatalyst film on the surface of the substrate. And a method for producing a photocatalyst carrier, wherein a fluorine compound is contained in the compound solution. 23. The metal oxide photocatalyst film is obtained by coating the solution on the surface of the base material and heating in a oxidizing atmosphere, the compound solution containing titanium alkoxide and trifluoroacetic acid. 23. The method for producing a photocatalyst carrier according to item 22.