JP2009022826A - Method for producing visible light responsive photocatalyst, and photocatalyst carrying structure - Google Patents

Abstract

【Task】
A method of easily and efficiently producing a visible light responsive photocatalyst using crystalline titanium oxide contained in papermaking sludge and the like and titanium oxide having low photocatalytic activity widely used for pigments, and the like, and Provided is a photocatalyst-supporting structure having a visible light responsive photocatalyst layer on a substrate.
[Solution]
The step (I) of bringing a substance containing a titanate into contact with at least one selected from a nitrogen-containing compound and a transition metal-containing compound, and the obtained contact product at 300 to 700 ° C. in an oxidative atmosphere A method for producing a visible light responsive photocatalyst comprising the step (II) of heating or acid treatment, and a visible light responsive type obtained by the production method on a substrate and the surface of the substrate. A photocatalyst carrying structure having a photocatalyst layer containing a photocatalyst.
[Selection figure] None.

Description

  The present invention relates to a method for producing a photocatalyst exhibiting photocatalytic activity by irradiating visible light, and a photocatalyst-supporting structure having the photocatalyst layer on a substrate directly or via another layer.

  When the photocatalyst is irradiated with light, electrons having a reducing action and holes having an oxidizing action are generated, and organic substances etc. in contact with the photocatalyst can be decomposed by the redox action. Using such a photocatalyst, decomposition of NOx in the atmosphere, decomposition and removal of malodorous substances and molds in living spaces and work spaces, decomposition and removal of organic solvents, agricultural chemicals, surfactants, etc. in water are examined. Has been.

  Conventionally, it was thought that it was necessary to irradiate ultraviolet rays in order to develop the activity of the photocatalyst. However, in recent years, titanium oxide exhibiting catalytic activity by irradiating visible light (hereinafter referred to as “visible light responsive photocatalyst”). Have been discovered, and several methods for producing the visible light responsive photocatalyst have been proposed.

  For example, Patent Document 1 describes a method for producing a visible light responsive photocatalyst by bringing amorphous titanium hydroxide into contact with ammonia water and then baking at 300 to 600 ° C.

  Patent Document 2 describes a method for producing a visible light responsive photocatalyst by baking an amorphous titanium oxide precursor at 300 to 600 ° C. in an ammonia-containing gas atmosphere.

  Patent Document 3 describes a titanium oxide photocatalyst in which anatase-type titanium oxide mainly exhibiting high photocatalytic activity in the ultraviolet wavelength region and anatase-type titanium oxide mainly exhibiting high photocatalytic activity in the visible light region are combined. . Therein, as a method for producing such a photocatalyst, a condition in which metatitanic acid showing anatase crystallinity is incorporated into amorphous orthotitanic acid containing an ammonium salt, and nitrogen-doped anatase-type titanium oxide is generated from orthotitanic acid. A method of firing below is described.

  Patent Document 4 describes a sol (photocatalyst particles) containing a transition metal compound-containing titanium oxide having a sedimentation component amount of less than 10% by mass of the total solid content. It is also described that the photocatalytic particles described in this document have a high photocatalytic activity under a light source having a wavelength of 400 nm or more and a good photocatalytic activity under a light source having a wavelength of 400 nm or less.

  As described above, various proposals have been made as a method for producing a visible light responsive photocatalyst. However, since each method is a method for newly synthesizing a visible light responsive photocatalyst from its precursor, the cost is high. A responsive photocatalyst could not be easily and efficiently produced at low cost.

  On the other hand, titanium oxide is used as a pigment added to paints and paper products. Titanium oxide is also contained in papermaking sludge, which is waste generated in the manufacturing process of paper products, and the use of this titanium oxide as a photocatalyst has been studied. However, titanium oxide used as a pigment has low photocatalytic activity, and does not exhibit photocatalytic activity even when irradiated with visible light.

JP 2001-278626 A JP 2001-354422 A JP-A-2005-55746 JP-A-2005-97096

  The present invention has been made in view of the above-described conventional technology, and uses a cheap titanium oxide contained in paper sludge or the like as it is, and a method for easily and efficiently producing a visible light responsive photocatalyst, and Another object of the present invention is to provide a photocatalyst-supporting structure having a visible light responsive photocatalyst layer on a substrate.

  In order to solve the above problems, the present inventors obtained a titanate having a cation exchange ability by heat-treating titanium oxide contained in paper sludge and the like with a sodium hydroxide aqueous solution. And after processing this titanate with the aqueous solution of ammonium salt or a transition metal salt, it discovers that a visible light responsive type titanium oxide can be efficiently manufactured by baking or processing with an acid, The present invention has been completed.

Thus, according to the first aspect of the present invention, the following methods (1) to (5) for producing a visible light responsive photocatalyst are provided.
(1) A step (I) of bringing a substance containing a titanate into contact with at least one selected from a nitrogen-containing compound and a transition metal-containing compound, and the obtained contact product in an oxidative atmosphere, 300 to A method for producing a visible light responsive photocatalyst, comprising a step (II) of heating to 700 ° C. or acid treatment.
(2) The method for producing a visible light responsive photocatalyst according to (1), wherein the titanate is obtained by alkali-treating titanium oxide.
(3) The method for producing a visible light responsive photocatalyst according to (2), wherein anatase type or rutile type titanium oxide is used as the titanium oxide.

(4) The method for producing a visible light responsive photocatalyst according to (2) or (3), wherein the alkali treatment comprises subjecting a mixture containing titanium oxide, a silicon compound, and an aluminum compound to an alkali treatment.
(5) The method for producing a visible light responsive photocatalyst according to any one of (2) to (4), wherein the alkali treatment is an alkali treatment on papermaking sludge or papermaking sludge incinerated ash containing titanium oxide. .

According to the second aspect of the present invention, the following photocatalyst-supporting structure (6) is provided.
(6) A photocatalyst-supporting structure having a base and a photocatalyst layer containing a visible light responsive photocatalyst obtained by the production method according to any one of (1) to (5) on the surface of the base.

  According to the production method of the present invention, a visible light responsive photocatalyst can be produced simply and efficiently at a low production cost by using titanium oxide contained in papermaking sludge or the like as it is.

  The production method of the present invention is a kind of a method for producing a visible light responsive photocatalyst referred to as a so-called dope method, and is a method in which titanium oxide contained in papermaking sludge can be used as it is. Therefore, the production method of the present invention, such as a method of producing visible light type (ultraviolet light type) titanium oxide from titanium chloride through titanium hydroxide (amorphous), generates chlorine during hydrolysis of the raw material, etc. It is possible to synthesize by a simple method without the danger of, so it can be handled by a normal chemical plant.

  Further, as a conventional cation doping method, a method called an ion implantation method has been mainstream. However, it is expensive to manufacture a visible light responsive photocatalyst by this method, and mass production is difficult. On the other hand, according to the present invention, the visible light responsive photocatalyst can be mass-produced at a low cost.

  According to the production method of the present invention, a part of O (oxygen) of Ti—O in titanium oxide is replaced with an anion such as N, and an anion-doped type visible light type or a part of Ti of Ti—O Replacing cations such as Cu and Fe with a cation-doped visible light type, replacing some Ti-O Ti with a cation such as Cu, and replacing O with an anion such as N and making visible Co-dope (bi-doped) The optical mold can be manufactured by a simple method.

  The photocatalyst-supporting structure of the present invention is formed by forming the layer of the visible light responsive photocatalyst of the present invention on the substrate directly or via another layer, and is therefore excellent when irradiated with visible light. In addition to exhibiting photocatalytic activity, it can be produced at a low production cost.

Hereinafter, the present invention will be described in detail by dividing it into 1) a method for producing a visible light responsive photocatalyst and 2) a photocatalyst carrying structure.
In the present invention, the “visible light responsive photocatalyst” refers to a titanium oxide compound having a property of exhibiting photocatalytic activity when irradiated with visible light having a wavelength of 450 nm to 780 nm.
In addition, the “visible light responsive photocatalyst” in the present invention includes not only visible light having a wavelength of 450 nm to 780 nm but also a titanium oxide compound having a property of exhibiting photocatalytic activity when irradiated with ultraviolet light having a wavelength of less than 450 nm. Including.

1) Method for Producing Visible Light Responsive Photocatalyst The method for producing a visible light responsive photocatalyst of the present invention is a step of bringing a substance containing titanate into contact with at least one selected from a nitrogen-containing compound and a transition metal-containing compound. The method includes (I) and a step (II) in which the obtained contact product is heated to 300 to 700 ° C. in an oxidizing atmosphere or is acid-treated.

(1) Titanate Specific examples of the titanate used in the present invention include polyvalent titanium containing protons such as trititanic acid, tetratitanic acid, pentatitanic acid, hexatitanic acid, heptanic acid, octatitanic acid, etc. Acid; polyvalent titanates such as potassium titanate, calcium titanate, cesium titanate, sodium titanate, magnesium titanate, aluminum titanate, strontium titanate and barium titanate;

As the titanate, those obtained by alkali treatment of titanium oxide are preferable.
As titanium oxide, titanium oxide having crystallinity is preferable, and the crystal form is not particularly limited. For example, anatase-type titanium oxide, rutile-type titanium oxide, brookite-type titanium oxide, a mixture of two or more kinds of titanium oxides, and the like can be given.

  Further, the titanium oxide used in the present invention may be either crystalline titanium oxide having low photocatalytic activity with respect to ultraviolet rays or crystalline titanium oxide having high photocatalytic activity with respect to ultraviolet rays.

  As the former crystalline titanium oxide having low photocatalytic activity with respect to ultraviolet rays, inexpensive crystalline titanium oxide having low photocatalytic activity contained in paper sludge and the like that has been discarded without being used so far can be mentioned.

  In the present invention, when alkali treatment of titanium oxide is performed on a mixture containing titanium oxide, a silicon compound, and an aluminum compound, a composite of visible light responsive photocatalyst and zeolite can be obtained.

Examples of the silicon compound include sodium silicate and silicate glass, and examples of the aluminum compound include alumina (Al ₂ O ₃ ), aluminum nitrate, aluminum sulfate, aluminum hydroxide, and aluminum chloride.
Although the addition amount of a silicon compound and an aluminum compound is not specifically limited, Usually, a silicon compound is 10-1000 mass parts and an aluminum compound is 10-1000 mass parts with respect to 100 mass parts of titanium oxide.

  In the alkali treatment of titanium oxide, it is preferable that the papermaking sludge or the papermaking sludge incinerated ash containing titanium oxide is subjected to an alkali treatment. By using paper sludge or paper sludge incinerated ash that has been conventionally discarded, a visible light responsive photocatalyst can be produced at low cost.

  Further, a mixture further containing at least one selected from the group consisting of a phosphorus compound, a zirconium compound, a calcium compound, a magnesium compound, an alkaline earth metal, and a cellulose polymer may be subjected to an alkali treatment.

  When crystalline titanium oxide having high photocatalytic activity with respect to ultraviolet rays is used, as described later, a part of crystalline titanium oxide having high photocatalytic activity with respect to ultraviolet rays is converted into visible light by the method of the present invention. An ultraviolet light / visible light responsive photocatalyst can be produced by converting to a responsive photocatalyst and leaving the rest of the crystalline titanium oxide having a high photocatalytic activity for ultraviolet light.

  Here, “ultraviolet light / visible light responsive photocatalyst” means an oxidation that exhibits photocatalytic activity when irradiated with ultraviolet rays and also exhibits photocatalytic activity when irradiated with visible light. Refers to a titanium compound.

  The alkali used for the alkali treatment of titanium oxide may be either an inorganic base or an organic base. However, in order to obtain a desired visible light responsive photocatalyst efficiently, the use of an inorganic base is preferable.

  Examples of inorganic bases include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide; alkaline earth metal hydroxides such as magnesium hydroxide, calcium hydroxide and barium hydroxide; sodium carbonate and potassium carbonate And alkali metal carbonates such as magnesium carbonate, calcium carbonate, and barium carbonate. Among these, alkali metal hydroxides are more preferable, and sodium hydroxide and potassium hydroxide are particularly preferable.

  The usage-amount of an alkali is 0.1-100 mass parts normally with respect to 1 mass part of titanium oxide, Preferably it is 1-50 mass parts.

  The method of alkali-treating titanium oxide is not particularly limited as long as titanium oxide and alkali react with each other to obtain an alkali-treated product. For example, there is a method in which a predetermined amount of titanium oxide is added to an alkaline aqueous solution and the whole volume is heated and reacted.

The concentration of the aqueous alkali solution used is usually 1 to 20 mol / liter, preferably 5 to 15 mol / liter.
The reaction temperature is usually 20 ° C. to 200 ° C., and the reaction time is usually 1 minute to 100 hours.

  After the titanium oxide is alkali-treated, the aqueous alkali solution is centrifuged to recover the solid content, washed with distilled water, and centrifuged again several times. The recovered solid content is then adjusted to 30 to 120 ° C. Then, the alkali-treated product can be isolated by drying for 10 minutes to 24 hours.

  A titanate can be obtained as described above. The titanate varies depending on the alkali used. For example, when sodium hydroxide is used, sodium titanate is obtained. The obtained titanate has ion exchange capacity (cation exchange capacity).

(2) Step (I)
Step (I) is a step of bringing a substance containing titanate into contact with at least one selected from a nitrogen-containing compound and a transition metal-containing compound.

The nitrogen-containing compound to be used is not particularly limited as long as it is a substance capable of obtaining a compound in which a part of oxygen atoms of titanium oxide is substituted with nitrogen atoms by contacting with the alkali-treated product. For example, ammonia water; ammonium salts such as ammonium chloride (NH ₄ Cl), ammonium nitrate (NH ₄ NO ₃ ), ammonium acetate, and ammonium sulfate;

  The transition metal-containing compound to be used is not particularly limited as long as it is a substance capable of obtaining a compound in which a part of the titanium atom of titanium oxide is substituted with a transition metal atom by contacting with the alkali-treated product. And transition metal salts.

As the transition metal of the transition metal salt, metals in Group 4 to Group 12, Group 5 to Group 12, and Period 6 of the Periodic Table (Long Period Type), and 6th Period Examples include metals of Group 3 to Group 12, and metals of Group 4 to Group 12 of the fourth period are preferable.
More specifically, scandium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc may be mentioned.

Examples of the transition metal salt include inorganic salts and organic salts of transition metals.
Examples of inorganic salts of transition metals include halides such as fluorides, chlorides, bromides, and iodides; salts of inorganic acids such as nitrates, sulfates, and phosphates. More specifically, ferric chloride (III) (FeCl ₃ ), ferric nitrate (Fe (NO ₃ ) ₃ ), copper sulfate (CuSO ₄ ), copper nitrate (Cu (NO ₃ ) ₂ ), nitric acid And chromium (Cr (NO ₃ ) ₃ ).
Examples of organic salts of transition metals include salts of organic acids such as acetates, oxalates, and citrates; chelate compounds such as acetylacetonate and acetoacetate.

  These nitrogen-containing compounds and transition metal-containing compounds can be used alone or in combination of two or more.

  For example, (a) an anion-doped visible light type in which a part of O (oxygen) of Ti—O is replaced with an anion such as N by contacting an alkali-treated product with a nitrogen-containing compound, or (b) an alkali A cation-doped visible light type in which a part of Ti in Ti—O is replaced with a transition metal cation such as Cu or Fe by bringing the treated product into contact with a transition metal-containing compound. Co-dope in which a part of Ti in Ti—O is replaced with a transition metal cation such as Cu and a part of O is replaced with an anion such as N by treatment with a containing compound and further with a transition metal containing compound. A (double doped) visible light type can be produced.

  The amount of the nitrogen-containing compound or transition metal-containing compound used is 0.0005 to 100 parts by mass, preferably 0.001 to 10 parts by mass with respect to 1 part by mass of the alkali-treated product. .

The nitrogen-containing compound or transition metal-containing compound is preferably used as an aqueous solution. The concentration of the nitrogen-containing compound in the aqueous solution to be used is 0.01 to 10 mol / liter, preferably 0.05 to 5 mol / liter, more preferably 0.5 to 3 mol / liter.
The concentration of the transition metal-containing compound is 0.0001 to 10 mol / liter, preferably 0.0005 to 5 mol / liter, and more preferably 0.003 to 1 mol / liter.

  As a method of bringing the alkali-treated product into contact with at least one selected from a nitrogen-containing compound and a transition metal-containing compound (hereinafter sometimes referred to as “nitrogen-containing compound”), an aqueous solution of a nitrogen-containing compound or the like is alkalinized. There is a method in which a predetermined amount of the processed product is added and the whole volume is stirred and shaken.

  The temperature when stirring and shaking the entire volume is usually 10 to 50 ° C. The time for stirring and shaking the whole volume is from several minutes to several hours.

  After contacting the alkali-treated product with a nitrogen-containing compound or the like, the whole volume is centrifuged to collect a solid content, washed with distilled water, and centrifuged again several times. Can be isolated by drying at 30-200 degreeC.

(3) Process (II)
Step (II) is a step in which the contact product obtained in step (I) is heated to 300 to 700 ° C. in an oxidizing atmosphere or subjected to an acid treatment.

As a method of heating the contact product obtained in the step (I) to 300 to 700 ° C. in an oxidative atmosphere, a method of heating to 300 to 700 ° C. in air, or a mixture of oxygen gas and inert gas. The method of heating to 300-700 degreeC in gas is mentioned.
The heating time is usually several minutes to several tens of hours, preferably 30 minutes to 10 hours.

  As a method of treating the contact product obtained in step (I) with an acid, the contact product obtained in step (I) is suspended in water, a predetermined amount of acid is added thereto, and the entire volume is determined in advance. The method of stirring at temperature is mentioned. Moreover, a predetermined amount of acid can be added and the whole volume can be stirred at predetermined temperature, without isolating a contact thing from the reaction liquid obtained at process (I).

Examples of the acid used here include inorganic acids such as hydrochloric acid (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), and phosphoric acid; and organic acids such as formic acid and acetic acid. The acid used is preferably one diluted with water. The acid concentration is 0.01 to 10 mol / liter, preferably 0.1 to 3 mol / liter.

  The temperature when the contact is treated with an acid is usually 10 to 200 ° C., and the treatment time is several minutes to 50 hours, preferably several minutes to 12 hours.

  In addition, you may perform the acid treatment of this process (II) simultaneously with the process of said (I). That is, the nitrogen-containing compound and the acid may be brought into contact with the alkali-treated product.

After the contact product is treated with an acid, the whole volume is centrifuged to collect a solid content, washed with distilled water, and centrifuged again several times. After that, the collected solid content is reduced to 30 to 120. The desired visible light responsive photocatalyst can be obtained by drying at 0 ° C.
The object can be identified by elemental analysis, X-ray diffraction measurement, or the like.

  As described above, in the present invention, crystalline titanium oxide having high photocatalytic activity with respect to ultraviolet rays is used as a starting material, a part of the crystalline titanium oxide is alkali-treated, and the resulting alkali-treated product is treated with nitrogen. By contacting with at least one selected from the containing compound and the transition metal-containing compound, and then heating the obtained contact product to 300 to 700 ° C. in an oxidative atmosphere or acid treatment, A visible light responsive photocatalyst can be produced.

  A method of alkali-treating a part of crystalline titanium oxide having a high photocatalytic activity with respect to ultraviolet rays, a method of contacting the obtained alkali-treated product with at least one selected from a nitrogen-containing compound and a transition metal-containing compound, and The method for heating the obtained contact product to 300 to 700 ° C. in an oxidative atmosphere or performing an acid treatment is the same as the method described in the section for producing the visible light responsive photocatalyst of the present invention described above. .

2) Photocatalyst carrying structure The photocatalyst carrying structure of the present invention has a base and a photocatalyst layer containing a visible light responsive photocatalyst obtained by the production method of the present invention on the surface of the base.

The substrate used in the present invention is not particularly limited as long as it can support the photocatalyst of the present invention.
Examples of the base material include inorganic materials such as ceramics, glass, ceramics, enamel, and concrete; organic materials such as synthetic resins, fibers, papers, and wood materials; and metallic materials such as iron, aluminum, copper, and stainless steel And the like.

The shape of the substrate may be any shape such as a film shape, a sheet shape, a plate shape, a tubular shape, a fiber shape, and a net shape.
The thickness of the substrate is not particularly limited, but is preferably 10 μm or more because the adhesive layer and the photocatalyst layer can be firmly supported on the surface.
The substrate may be a single layer or a laminate.

  The photocatalyst layer may be formed directly on the substrate or may be formed via another layer. Other layers are not particularly limited as long as they can be formed between the substrate and the photocatalyst layer. For example, the adhesive layer mentioned later is mentioned.

  The adhesive layer is formed to improve the adhesion between the substrate and the photocatalyst layer and to prevent the substrate material from being deteriorated or decomposed by the photocatalyst.

  The adhesive layer can be formed by applying and drying the composition for forming an adhesive layer on the substrate surface directly or via another layer.

  The composition for forming an adhesive layer includes at least (a) silicon-modified resin such as acrylic-silicon resin and epoxy-silicon resin; (b) resin containing colloidal silica or polysiloxane (acrylic resin, acrylic-silicon resin, epoxy- 1 type or 2 or more types of resins selected from (c) hydrolyzate of silicon alkoxide or product from the hydrolyzate; silicon resin, urethane resin, epoxy resin, polyester resin, alkyd resin, etc.) If necessary, it can be prepared by dissolving in an appropriate solvent.

  Examples of the solvent used in the composition for forming an adhesive layer include aromatic hydrocarbons such as benzene, toluene, and xylene; methanol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, Examples thereof include alcohols such as t-butyl alcohol; esters such as ethyl acetate; and mixed solvents thereof.

  Moreover, a light stabilizer and / or an ultraviolet absorber can be blended with the composition for forming an adhesive layer for the purpose of suppressing deterioration due to photocatalytic action.

  Examples of the light stabilizer to be used include hindered amine light stabilizers, and examples of the ultraviolet absorber include triazole ultraviolet absorbers. The addition amount of the light stabilizer and / or ultraviolet absorber is preferably in the range of 0.005 wt% to 10 wt% with respect to the resin.

As a method for forming the adhesive layer on the substrate surface, the adhesive layer forming composition is coated on the substrate material surface by spraying by spray, roll coating method, dip coating method, etc., and then dried. Is mentioned.
The drying temperature of a coating film is 20-150 degreeC normally, Preferably it is 80-120 degreeC.

  Although there is no restriction | limiting in particular in the thickness of the contact bonding layer obtained, Usually, they are 0.1 micrometer-10 micrometers. When the thickness of the adhesive layer is 0.1 μm or more, the photocatalyst layer can be firmly adhered to form a highly durable photocatalyst carrying structure.

  The photocatalyst layer of the photocatalyst carrying structure of the present invention is formed from the composition for forming a photocatalyst layer containing the visible light responsive photocatalyst of the present invention. Examples of the method for forming the photocatalyst layer include a method in which a coating liquid containing the photocatalyst layer forming composition is applied to the substrate.

  The form of the visible light responsive photocatalyst in the composition for forming a photocatalyst layer may be any of powder, gel, and solution, but is preferably powder or gel. Among them, a gel-like one having an average particle diameter of 50 nm or less, preferably 20 nm or less improves the transparency of the photocatalyst layer and increases the linear transmittance. Therefore, a glass substrate or plastic molding that requires transparency is required. Particularly preferred when applied to the body.

  The content of the visible light responsive photocatalyst is preferably 5% by weight to 60% by weight in terms of oxide with respect to the entire solid content in the composition for forming a photocatalyst layer. When the amount is less than 5% by weight, the photocatalytic activity is remarkably lowered. On the other hand, when it exceeds 60% by weight, the photocatalytic activity is increased, but the adhesiveness with the adhesive layer is poor.

  The composition for forming a photocatalyst layer may contain a metal oxide gel or a metal hydroxide gel in addition to the visible light responsive photocatalyst of the present invention. Metal oxide gel or metal hydroxide gel is silicon oxide or silicon hydroxide gel and zirconium oxide or zirconium hydroxide gel and / or aluminum oxide or aluminum hydroxide gel Is preferred.

  The content of the metal oxide gel or metal hydroxide gel in the composition for forming a photocatalyst layer is not particularly limited, but from the viewpoint of obtaining excellent adhesion and weather resistance, 0 to 0 for the entire composition. It is preferably 50% by weight.

  The photocatalyst layer can be formed by applying the photocatalyst layer forming composition on the surface of the substrate or other layers and drying the resulting coating film.

  The composition for forming a photocatalyst layer can be prepared by dispersing or dissolving a visible light responsive photocatalyst and a metal oxide gel or metal hydroxide gel in an appropriate solvent.

  Examples of the solvent used for the preparation of the composition for forming a photocatalyst layer include water; alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, and t-butanol; acetone, methyl ethyl ketone, methyl isobutyl ketone, Ketones such as acetylacetone and cyclohexanone; ethers such as diethyl ether, methyl cellosolve and tetrahydrofuran; aromatic hydrocarbons such as benzene, toluene and xylene; halogenated hydrocarbons such as dichloromethane and chloroform; ethyl acetate, propyl acetate and acetic acid And esters such as butyl; saturated hydrocarbons such as n-pentane, n-hexane, and cyclohexane; and the like. These may be used alone or in combination of two or more. Among these, the use of a water-alcohol solvent is particularly preferable.

  The method for coating the photocatalyst layer forming composition is not particularly limited, and a known coating method can be employed. For example, a spraying method using a spray, a roll coating method, a dip coating method, and the like can be given.

A photocatalyst layer can be formed by drying the coating film obtained by coating the composition for forming a photocatalyst layer at a predetermined temperature.
The drying temperature of the coating film is usually in the range of room temperature to 150 ° C.

  The thickness after drying of the photocatalyst layer obtained as described above is 0.05 to 2 μm, preferably 0.5 to 1.5 μm. When the thickness of the photocatalyst layer is within this range, it is preferable because the surface of the coating film of the composition for forming a photocatalyst layer does not crack or peel off.

  The photocatalyst carrying structure of the present invention obtained as described above has a photocatalyst layer having a transparent and uniform film quality on the surface. By irradiating the photocatalyst layer of the photocatalyst carrying structure of the present invention with visible light, a function to prevent malodorous substances from adsorbing to the surface (odor-preventing function) and preventing dust and dirt from adhering to the surface It exhibits various functions such as a function to prevent (contamination prevention function), a function to decompose malodorous substances such as aldehydes, ammonia, and amines (malodorous substance decomposition function).

  The photocatalyst carrying structure of the present invention includes, for example, interior members such as blinds, curtains, carpets, various furniture, and lighting equipment; building members such as doors, wallpaper, window glass, and wall materials; It can be used for outdoor parts such as lights, highway and Shinkansen sound insulation walls; agricultural parts such as agricultural bi-films and weedproof sheets; packaging materials, ship bottom / fishnet prevention paints, water treatment fillers, black lights, etc.

  Next, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to the examples.

  In addition, the X-ray-diffraction measurement, the ultraviolet and visible light absorption spectrum analysis, and the acetaldehyde decomposition | disassembly test of the sample obtained by the following Example and comparative example were done as follows.

(1) X-ray diffraction measurement (XRD analysis)
XRD analysis was performed using an X-ray diffraction tester (RINT2000, manufactured by Rigaku Corporation).

(2) UV / VIS absorption spectrum measurement (UV-VIS absorption spectrum analysis)
The UV-VIS absorption spectrum was performed using a spectrophotometer (U-3500, manufactured by Hitachi, Ltd.).
For comparison, the UV-VIS absorption spectrum of anatase titanium oxide for pigments was also measured (see FIG. 9).

(3) Acetaldehyde degradation test The acetaldehyde degradation test was performed under the following two conditions.
(A) Acetaldehyde decomposition test (1)
Fluorescent lamp: 27W fluorescent lamp (Matsushita Electric Industrial Co., Ltd., illuminance 1000 lux)
UV cut film: Trade name: ObicC, manufactured by King Seisakusho (things that shield 400nm or less)
Reaction container: Glass 200 ml container Reactant: Acetaldehyde gas

(Experimental conditions)
As shown in FIG. 1, 0.1 g of each of samples 1 to 4 obtained in Examples and Comparative Examples is placed in a reaction vessel, acetaldehyde gas is injected so that the concentration in the reaction vessel is 1000 ppm, and adsorption is performed. After reaching equilibrium, fluorescent light was irradiated through a UV cut film. The concentration of acetaldehyde in the reaction vessel 24 hours after irradiation was measured with a gas chromatograph (GC390B, manufactured by GL Sciences).

(B) Acetaldehyde decomposition test (2)
Fluorescent lamp: 4W fluorescent lamp (Toshiba, illuminance 400 lux)
UV cut film: Trade name: ObicC, manufactured by King Seisakusho (things that shield 400nm or less)
Reaction container: Glass 10 liter container Reactant: Acetaldehyde gas

(Experimental conditions)
As shown in FIG. 1, 0.5 g of each of the obtained samples 5, 9, 10, 12, 14 to 16 is put in a reaction vessel, and acetaldehyde gas is injected so that the concentration in the reaction vessel is 20 ppm. After reaching the adsorption equilibrium, fluorescent light was irradiated through a UV cut film. The concentration of acetaldehyde 24 hours after irradiation was measured with a gas chromatograph (GC390B, manufactured by GL Sciences).

(Synthesis Example 1)
Anatase-type titanium oxide for pigment (Furukawa Machine Metal Co., Ltd., FA55W) 10 g, sodium hydroxide (Kanto Chemical Co., Ltd.) 40 g, distilled water 100 g made of polytetrafluoroethylene (hereinafter referred to as “PTFE”) having a volume of 250 ml. It added to the Erlenmeyer flask (alkali concentration 10 mol / liter). A conical tube was attached to the Erlenmeyer flask and heated for 72 hours under the boiling point maintaining condition. After the reaction, the operation of washing and centrifuging with distilled water was repeated three times, followed by drying for 24 hours with a drier set at 50 ° C. to obtain a white powder (sample 1) as an alkali-treated product (step (I)) ). Sample 1 was subjected to XRD analysis and acetaldehyde decomposition test.
The XRD analysis result of Sample 1 is shown in FIG. 2 together with the analysis result of anatase-type titanium oxide for pigment (in the figure, described as “anatase for pigment”, the same applies hereinafter). Table 1 shows the acetaldehyde decomposition test results. From the XRD analysis result of Sample 1 shown in FIG. 2, it was confirmed that Sample 1 was sodium titanate.

Example 1
Add 1 g of sample 1 and 30 ml of NH ₄ Cl aqueous solution (1 mol / liter) as a nitrogen-containing compound to a 50 ml centrifuge tube, shake for 1 hour and then centrifuge twice. Wash and centrifuge with 30 ml distilled water. Repeated twice (step (I)).
The supernatant liquid was discarded, and the white substance that was a contact product with the obtained nitrogen-containing compound was heated (fired) in air at 500 ° C. for 2 hours to obtain a yellow powder (sample 2) (step (II )).
Sample 2 was subjected to XRD analysis, UV-VIS absorption spectrum analysis, and acetaldehyde decomposition test.
The XRD analysis results are shown in FIG. 2, the acetaldehyde decomposition test results are shown in Table 1, and the UV-VIS absorption spectrum analysis results are shown in FIG.

  From the XRD analysis result of Sample 2 shown in FIG. 2, it was confirmed that Sample 2 was a compound having a structure of anatase-type titanium oxide. Moreover, as shown in FIG. 9, absorption was recognized by the sample 2 at 350 nm-550 nm vicinity.

(Example 2)
Add 1 g of sample 1 and 30 ml of NH ₄ Cl aqueous solution (1 mol / liter) as a nitrogen-containing compound to a 50 ml centrifuge tube, shake for 1 hour, and then centrifuge twice. Wash and centrifuge with 30 ml distilled water. Went. Furthermore, 10 ml of FeCl ₃ aqueous solution (0.001 mol / liter) is added as a transition metal-containing compound, shaken for 10 minutes, centrifuged, discarded the supernatant, washed with 30 ml distilled water and centrifuged. Thus, an ocherous substance was obtained (step (I)).
The obtained ocherous material was heated (baked) at 500 ° C. for 2 hours to obtain a brown powder (sample 3) (step (II)). Sample 3 was subjected to XRD analysis, UV-VIS absorption spectrum analysis and acetaldehyde decomposition test.

The XRD analysis results are shown in FIG. 2, the acetaldehyde decomposition test results are shown in Table 1, and the UV-VIS absorption spectrum analysis results are shown in FIG.
From the XRD analysis result of Sample 3 shown in FIG. 2, it was confirmed that Sample 3 was a compound having a structure of anatase-type titanium oxide. Moreover, as shown in FIG. 9, absorption was recognized by the sample 3 at 350 nm-700 nm vicinity.

(Example 3)
Add 1 g of sample 1 and 30 ml of NH ₄ Cl aqueous solution (1 mol / liter) as a nitrogen-containing compound to a 50 ml centrifuge tube, shake for 1 hour and then centrifuge twice. Discard the supernatant and wash with 30 ml distilled water. Work to centrifuge.
Further, add 10 ml of CuSO ₄ aqueous solution (0.001 mol / liter) as a transition metal-containing compound, shake for 10 minutes, perform centrifugation, discard the supernatant, wash with 30 ml distilled water, and perform centrifugation. Thus, a blue substance was obtained (step (I)). The obtained blue substance was heated (baked) at 500 ° C. for 2 hours to obtain a yellow-green powder (sample 4) (step (II)). Sample 4 was subjected to XRD analysis and acetaldehyde decomposition test.
The XRD analysis results are shown in FIG. Table 1 shows the acetaldehyde decomposition test results.
From the XRD analysis result of Sample 4 shown in FIG. 2, it was confirmed that Sample 4 was a compound having a structure of anatase-type titanium oxide. Moreover, as shown in FIG. 10, absorption was recognized by the sample 4 at 350 nm-650 nm vicinity.

Example 4
In a PTFE container with a volume of 50 ml, 1 g of sample 1, 20 ml of NH ₄ NO ₃ aqueous solution (1 mol / liter) as a nitrogen-containing compound, 10 ml of Fe (NO ₃ ) ₃ aqueous solution (0.01 mol / liter) as a transition metal-containing compound, HNO ₃ Aqueous solution (1 mol / liter) (50 ml) was added, the lid made of PTFE was covered, and the mixture was allowed to stand at 100 ° C. for 6 hours (step (I) and step (II)). After the reaction, it was washed twice with 50 ml distilled water and then dried for 24 hours with a dryer set at 50 ° C. to obtain a yellow powder (Sample 5). Sample 5 was subjected to XRD analysis and acetaldehyde decomposition test.
The XRD analysis results are shown in FIG. Table 1 shows the acetaldehyde decomposition test results.
From the XRD analysis result of Sample 5 shown in FIG. 3, it was confirmed that Sample 5 is a mixture of a compound having an anatase-type titanium oxide structure and a compound having a rutile-type titanium oxide structure. Moreover, as shown in FIG. 10, absorption was recognized by the sample 5 at 350 nm-460 nm vicinity.

(Example 5)
In a PTFE container having a volume of 50 ml, 1 g of sample 1, 20 ml of NH ₄ NO ₃ aqueous solution (1 mol / liter) as a nitrogen-containing compound, 10 ml of Cu (NO ₃ ) ₂ aqueous solution (0.01 mol / liter) as a transition metal-containing compound, HNO ₃ Aqueous solution (1 mol / liter) (50 ml) was added, the lid made of PTFE was covered, and the mixture was allowed to stand at 100 ° C. for 6 hours (step (I) and step (II)). After the reaction, it was washed twice with 50 ml distilled water and then dried for 24 hours with a dryer set at 50 ° C. to obtain a yellow powder (Sample 6). Sample 6 was subjected to XRD analysis, UV-VIS absorption spectrum analysis, and acetaldehyde decomposition test.
The XRD analysis results are shown in FIG. 3, the acetaldehyde decomposition test results are shown in Table 1, and the UV-VIS absorption spectrum analysis results are shown in FIG.

  From the XRD analysis result of Sample 6 shown in FIG. 3, it was confirmed that Sample 6 was a mixture of a compound having an anatase-type titanium oxide structure and a compound having a rutile-type titanium oxide structure. Moreover, as shown in FIG. 9, absorption was recognized by the sample 6 near 350 nm -460 nm.

(Comparative Example 1)
Sample 1 was baked at 500 ° C. for 2 hours to obtain a white powder (Sample 7). Sample 7 was subjected to XRD analysis and acetaldehyde decomposition test.
The XRD analysis results are shown in FIG. Table 1 shows the acetaldehyde decomposition test results.
From the XRD analysis result of Sample 7 shown in FIG. 4, it was confirmed that Sample 7 was sodium titanate.

(Example 6)
Paper sludge incineration ash containing anatase-type titanium oxide (Al ₂ O ₃ : 70 wt%, TiO ₂ : 10 wt%, MgO: 20 wt%) 5 g, sodium hydroxide (Kanto Chemical Co., Ltd.) 6 g, distilled water 50 g , And 15 g of water glass No. 3 (sodium silicate, manufactured by Miwa Chemical Co., Ltd.) were added to a 300 ml Erlenmeyer flask. A conical tube was attached to the Erlenmeyer flask and heated for 4 hours under the boiling point maintaining condition. After the reaction, the operation of washing and centrifuging with distilled water was repeated three times and dried for 24 hours with a dryer set at 50 ° C. to obtain a white powder (Sample 8).
Sample 8 was subjected to XRD analysis. The XRD analysis results are shown in FIG.
As can be seen from FIG. 5, faujasite type zeolite was produced. Sample 8 also contained anatase-type titanium oxide contained in papermaking sludge incineration ash.

Add 1 g of sample 8 and 30 ml of NH ₄ Cl aqueous solution (1 mol / liter) as a nitrogen-containing compound to a 50 ml centrifuge tube, shake for 1 hour, and then centrifuge twice. Wash and centrifuge with 30 ml distilled water. Was repeated twice (step (I)). The supernatant was discarded, and the obtained white substance was baked at 500 ° C. for 2 hours to obtain a white powder (sample 9) (step (II)). Sample 9 was subjected to XRD analysis, acetaldehyde decomposition test and UV-VIS absorption spectrum analysis.
The XRD analysis result of Sample 9 is shown in FIG. 5 together with the XRD analysis result of paper sludge incineration ash. In addition, the acetaldehyde decomposition test results are shown in Table 1, and the UV-VIS absorption spectrum analysis results are shown in FIG.
FIG. 5 shows that an anatase-type titanium oxide contains a faujasite type zeolite.

(Example 7)
In a container made of polytetrafluoroethylene (PTFE) having a volume of 50 ml, Sample 1 (1 g), 20 ml of NH ₄ NO ₃ aqueous solution (1 mol / liter) as a nitrogen-containing compound, and Cr ₂ (NO ₃ ) ₃ aqueous solution as a transition metal-containing compound ( 10 ml of 0.01 mol / liter) and 50 ml of H ₂ SO ₄ aqueous solution (1 mol / liter) were added, covered with PTFE, and allowed to stand at 100 ° C. for 6 hours (step (I) and step (II)). ). After the reaction, it was washed twice with 50 ml distilled water and then dried for 24 hours with a dryer set at 50 ° C. to obtain a light yellow powder (sample 10). Sample 10 was subjected to XRD analysis, UV-VIS absorption spectrum analysis, and acetaldehyde decomposition test.
The XRD analysis result is shown in FIG. 6, the acetaldehyde decomposition test result is shown in Table 1, and the UV-VIS absorption spectrum analysis result is shown in FIG.

(Example 8)
5 g of anatase-type titanium oxide for photocatalyst (trade name “ST-01”, manufactured by Ishihara Sangyo Co., Ltd.), 40 g of sodium hydroxide (manufactured by Kanto Chemical Co., Ltd.) and 100 g of distilled water were added to a 250 ml PTFE Erlenmeyer flask. A conical tube was attached to the Erlenmeyer flask and heated for 10 minutes under the boiling point maintaining condition. After the reaction, the operation of washing and centrifuging with distilled water was repeated three times and dried for 24 hours with a dryer set at 50 ° C. to obtain a white powder (Sample 11). Sample 11 was subjected to XRD analysis and UV-VIS absorption spectrum analysis. The XRD analysis result is shown in FIG. 7 together with the analysis result of the anatase type titanium oxide for photocatalyst (denoted as “ST-01” in the figure). The results of UV-VIS absorption spectrum analysis are shown in FIG.
As a result of XRD analysis of Sample 11, sodium titanate and anatase-type titanium oxide were confirmed, and a part of the raw material anatase titanium oxide particles was changed to sodium titanate.

Next, in a PTFE container having a volume of 50 ml, 1 g of sample 11, 20 ml of NH ₄ NO ₃ aqueous solution (1 mol / liter) as a nitrogen-containing compound, and Fe (NO ₃ ) ₃ aqueous solution (0.1 mol / liter) as a transition metal-containing compound ) 10 ml, H ₂ SO ₄ aqueous solution (1 mol / liter) 50 ml was added, the lid made of PTFE was added, and the mixture was allowed to stand at 100 ° C. for 6 hours (step (I) and step (II)). Then, after washing twice with 50 ml distilled water, it was dried with a dryer set at 50 ° C. for 24 hours to obtain a yellow powder (sample 12). Sample 12 was subjected to XRD analysis, acetaldehyde decomposition test and UV-VIS absorption spectrum analysis.
The XRD analysis results are shown in FIG. 7, the acetaldehyde decomposition test results are shown in Table 1, and the UV-VIS absorption spectrum analysis results are shown in FIG.

  From the XRD analysis result of the sample 12 shown in FIG. 7, since the peak indicating sodium titanate disappeared and only anatase was obtained, and a yellow powder was obtained, sodium titanate was oxidized by visible light responsive anatase type oxidation. It is thought that it changed to titanium.

Example 9
10 g of rutile titanium oxide (manufactured by Kanto Chemical Co., Inc.), 40 g of sodium hydroxide (manufactured by Kanto Chemical Co., Ltd.) and 100 g of distilled water were added to a 250 ml PTFE Erlenmeyer flask. A conical tube was attached to the Erlenmeyer flask and heated for 72 hours under the boiling point maintaining condition. After the reaction, the operation of washing and centrifuging with distilled water was repeated three times, and dried for 24 hours with a dryer set at 50 ° C. to obtain a white powder (Sample 13). The XRD analysis result of Sample 13 is shown in FIG. 8 together with the analysis result of rutile-type titanium oxide (denoted as “rutile” in the figure, the same applies hereinafter). From the XRD analysis results, it was confirmed that in sample 13, a part of the rutile titanium oxide was changed to sodium titanate.

The work of adding 1 g of sample 13 and 30 ml of NH ₄ Cl aqueous solution (1 mol / liter) to a 50 ml centrifuge tube, shaking for 1 hour and then centrifuging was repeated twice, and washing and centrifuging with 30 ml distilled water was repeated twice. (Step (I)). The supernatant liquid was discarded, and the obtained white substance was baked at 500 ° C. for 2 hours to obtain a yellow powder (sample 14) (step (II)).
Sample 14 was subjected to XRD analysis, UV-VIS absorption spectrum analysis, and acetaldehyde decomposition test. The XRD analysis results are shown in FIG. 8, the acetaldehyde decomposition test results are shown in Table 1, and the UV-VIS absorption spectrum analysis results are shown in FIG.

(Example 10)
In a PTFE container having a volume of 50 ml, 1 g of sample 13, 20 ml of NH ₄ NO ₃ aqueous solution (1 mol / liter), 10 ml of Fe (NO ₃ ) ₃ aqueous solution (0.01 mol / liter), 50 ml of HNO ₃ aqueous solution (1 mol / liter) In addition, it was covered with PTFE and allowed to stand at 100 ° C. for 6 hours (step (I) and step (II)). Then, after washing twice with 50 ml distilled water, it was dried with a dryer set at 50 ° C. for 24 hours to obtain a yellow powder (sample 15). Sample 15 was subjected to XRD analysis, acetaldehyde decomposition test and UV-VIS absorption spectrum analysis. The XRD analysis results are shown in FIG. 8, the acetaldehyde decomposition test results are shown in Table 1, and the UV-VIS absorption spectrum analysis results are shown in FIG.

(Example 11)
In a PTFE container having a capacity of 50 ml, 1 g of sample 13, 20 ml of NH ₄ NO ₃ aqueous solution (1 mol / liter), 10 ml of Cu (NO ₃ ) ₂ aqueous solution (0.01 mol / liter), 50 ml of HNO ₃ aqueous solution (1 mol / liter) In addition, it was covered with PTFE and allowed to stand at 100 ° C. for 6 hours (step (I) and step (II)). Then, after washing twice with 50 ml distilled water, it was dried for 24 hours with a drier set at 50 ° C. to obtain a yellow powder (sample 16). Sample 16 was subjected to XRD analysis, acetaldehyde decomposition test and UV-VIS absorption spectrum analysis. The XRD analysis results are shown in FIG. 8, the acetaldehyde decomposition test results are shown in Table 1, and the UV-VIS absorption spectrum analysis results are shown in FIG.

From Table 1, after 24 hours, in the case of Samples 2 to 6, 9, 10, 12, and 14 to 16 of Examples 1 to 11, the acetaldehyde gas concentration is compared with the adsorption equilibrium concentration. It was confirmed that these samples had photocatalytic activity for visible light.
On the other hand, Sample 1 (sodium titanate) of Synthesis Example 1 and Sample 7 of Comparative Example 1 obtained by firing Sample 1 showed no photocatalytic activity for visible light.

Example 12
In an automatic square sheet machine (No. 2557, manufactured by Kumagai Riki Kogyo Co., Ltd.), 2 g of softwood kraft pulp (NBKP) absolutely dried was mixed with 0.3 g of Sample 3 obtained in Example 2, and 25 cm × 25 cm. Three sheets were prepared. In order to measure the visible light photocatalytic ability of these sheets, a decomposition test of acetaldehyde was performed in the following manner.

(Acetaldehyde degradation test)
Fluorescent lamp: 4W fluorescent lamp (Toshiba)
UV cut film: Trade name: ObicC, manufactured by King Seisakusho (things that shield 400nm or less)
Reaction vessel: Glass 10L vessel Reactant: Acetaldehyde gas Experimental condition: 25cm x 25cm 3 sheets

Acetaldehyde gas was injected so that the concentration in the reaction vessel was 20 ppm, and after reaching adsorption equilibrium, a fluorescent lamp was irradiated, and the acetaldehyde concentration after 24 hours of irradiation was measured.
As a result, the adsorption equilibrium concentration of acetaldehyde before irradiation was 10 ppm, whereas the concentration of acetaldehyde after 24 hours irradiation was 2.6 ppm.
From this result, it was confirmed that the photocatalyst layer carrying sheet of Example 12 has photocatalytic activity with respect to visible light.

It is a figure which shows the outline | summary of an acetaldehyde decomposition test. It is a XRD spectrum figure of samples 1-4 and anatase type titanium oxide for pigments (in the figure, a vertical axis expresses intensity (cps) and a horizontal axis expresses deviation angle 2theta (degree) from an X-ray incidence direction. The same applies to the following). It is a XRD spectrum figure of sample 1, 5, 6 and the anatase type titanium oxide for pigments. It is a XRD spectrum figure of sample 1, 7 and the anatase type titanium oxide for pigments. It is a XRD spectrum figure of samples 8 and 9 and papermaking sludge incineration ash. 3 is an XRD spectrum diagram of Sample 10. FIG. It is a XRD spectrum figure of samples 11 and 12 and anatase type titanium oxide (ST-01) for photocatalysts. It is a XRD spectrum figure of samples 13-16 and a rutile type titanium oxide. It is a UV-VIS absorption spectrum figure of sample 2, sample 3, sample 6, and anatase type titanium oxide for pigments (in the figure, the vertical axis represents reflectance (%) and the horizontal axis represents wavelength (nm). The same). It is a UV-VIS absorption spectrum figure of sample 4, 5 and the anatase type titanium oxide for pigments. It is a UV-VIS absorption spectrum figure of samples 9-12. It is a UV-VIS absorption spectrum figure of samples 14-16 and rutile type titanium oxide.

Claims (6)

  The step (I) of bringing a substance containing a titanate into contact with at least one selected from a nitrogen-containing compound and a transition metal-containing compound, and the obtained contact product at 300 to 700 ° C. in an oxidative atmosphere A method for producing a visible light responsive photocatalyst comprising a step (II) of heating or acid treatment.   The method for producing a visible light responsive photocatalyst according to claim 1, wherein the titanate is obtained by subjecting titanium oxide to an alkali treatment.   The method for producing a visible light responsive photocatalyst according to claim 2, wherein anatase or rutile titanium oxide is used as the titanium oxide.   The method for producing a visible light responsive photocatalyst according to claim 2 or 3, wherein the alkali treatment is an alkali treatment on a mixture containing titanium oxide, a silicon compound, and an aluminum compound.   The method for producing a visible light responsive photocatalyst according to any one of claims 2 to 4, wherein the alkali treatment is an alkali treatment of paper sludge or paper sludge incinerated ash containing titanium oxide.   A photocatalyst-supporting structure having a substrate and a photocatalyst layer containing a visible light responsive photocatalyst obtained by the production method according to claim 1 on the surface of the substrate.

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