Photocatalyst cell, hydrogen gas generation system, and photocatalyst sheet

Abstract

To provide a photocatalyst cell from which an electrolyte containing no photocatalyst particles can be easily taken out.SOLUTION: The photocatalytic cell of the present invention is a photocatalytic cell containing a photocatalytic sheet and an electrolytic solution, wherein the photocatalytic sheet includes a support sheet having a plurality of fibers bonded to each other, and a plurality of photocatalytic particles supported or fixed on the support sheet, the photocatalytic particles include tungsten oxide particles, and a mass of the photocatalytic particles per unit area of the photocatalytic sheet is 20g / m2 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photocatalytic cell, a hydrogen gas generation system, and a photocatalytic sheet. [Background technology]

[0002] Hydrogen gas is expected to be a next-generation energy source because it does not emit CO2 when used. In particular, "green hydrogen," produced by electrolyzing water using electricity from solar or wind power, is expected to be a promising energy source because it does not emit CO2 even during the production process. However, green hydrogen has the problem of high production costs. The electrolysis voltage of industrially used water electrolyzers is 1.5 to 2.1 V, which means it consumes a lot of power. A known device that can generate hydrogen gas from water at a low electrolysis voltage is one that combines a photocatalyst that reduces iron ions in an electrolyte with an electrolytic cell that generates hydrogen gas (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-157801 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional devices, iron ions are reduced by irradiating light onto photocatalyst particles dispersed in an electrolyte solution, which requires a filtration process to separate the photocatalyst particles from the electrolyte solution before it can be extracted. The present invention has been made in view of the above circumstances, and provides a photocatalytic cell from which an electrolyte solution that does not contain photocatalytic particles can be easily taken out. [Means for solving the problem]

[0005] The present invention provides a photocatalytic cell containing a photocatalyst sheet and an electrolyte solution, wherein the photocatalyst sheet comprises a carrier sheet having a plurality of fibers bonded thereto, and a plurality of photocatalyst particles supported or fixed on the carrier sheet, the photocatalyst particles comprising tungsten oxide particles, and the mass of the photocatalyst particles per unit area of ​​the photocatalyst sheet is 20 g / m 2 The present invention provides a photocatalytic cell characterized by the above. [Effects of the Invention]

[0006] In the photocatalyst sheet, photocatalyst particles containing tungsten oxide particles are supported or fixed on a carrier sheet having fibers. Therefore, the mass of photocatalyst particles per unit area of ​​the photocatalyst sheet is set to 20 g / m 2 As a result, light incident on the photocatalyst cell can be efficiently utilized for the photocatalytic reaction. Furthermore, the mass per unit volume of the photocatalyst sheet can be increased, allowing the photocatalyst sheet to be submerged in the electrolyte. Therefore, a photocatalyst sheet carrying or immobilizing photocatalyst particles can be placed in the photocatalyst cell, and the electrolyte solution not containing photocatalyst particles can be easily removed from the photocatalyst cell. Furthermore, the photocatalyst sheet can be prevented from floating, moving, bending, etc., and a reduction in the light-receiving area of ​​the photocatalyst sheet in the photocatalyst cell can be prevented. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view of a photocatalytic cell according to one embodiment of the present invention. [Figure 2] 1 is a schematic cross-sectional view of a hydrogen gas generation system according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] The photocatalyst cell of the present invention contains a photocatalyst sheet and an electrolyte. The photocatalyst sheet includes a carrier sheet having a plurality of fibers bonded thereto, and a plurality of photocatalyst particles supported or fixed on the carrier sheet. The photocatalyst particles include tungsten oxide particles, and the mass of the photocatalyst particles per unit area of ​​the photocatalyst sheet is 20 g / m. 2 That's all.

[0009] The average particle diameter D50 of the photocatalyst particles contained in the photocatalyst sheet is preferably 150 nm or more. At least a portion of the plurality of photocatalyst particles is preferably embedded in the carrier sheet having a plurality of fibrillated plant fibers. At least a portion of the plurality of photocatalyst particles is preferably embedded in the carrier sheet having a plurality of inorganic fibers. The pH of the electrolyte is preferably less than 2. Preferably, the electrolyte solution contains first cations, and the electrolyte solution and the photocatalyst particles are arranged so that the first cations are reduced to second cations by photocatalytic activity caused by the photocatalyst particles receiving light. The photocatalytic cell preferably has an inlet for supplying an electrolyte solution containing a first cation into the photocatalytic cell, and an outlet for discharging an electrolyte solution containing a second cation from the photocatalytic cell.

[0010] The present invention also provides a hydrogen gas generation system including the photocatalytic cell of the present invention and an electrolyzer having a cathode and an anode. The electrolyzer is configured to generate hydrogen gas from water or hydrogen ions at the cathode and to oxidize second cations to first cations at the anode. The photocatalytic cell and the electrolyzer are configured to supply an electrolyte containing the second cations generated in the photocatalytic cell to the electrolyzer, and to supply an electrolyte containing the first cations generated at the anode to the photocatalytic cell.

[0011] The present invention also provides a photocatalyst sheet for use in applications where at least a portion of the sheet is placed in a liquid. The photocatalyst sheet includes a carrier sheet having a plurality of fibers bonded thereto, and a plurality of photocatalyst particles supported or fixed on the carrier sheet. The photocatalyst particles include tungsten oxide particles. The mass of the photocatalyst particles per unit area of ​​the photocatalyst sheet is 20 g / m. 2 That's all.

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The configurations shown in the drawings and the following description are merely examples, and the scope of the present invention is not limited to those shown in the drawings and the following description.

[0013] Photocatalytic Cell FIG. 1 is a schematic cross-sectional view of a photocatalytic cell of this embodiment. The photocatalytic cell 13 of this embodiment contains a photocatalyst sheet 3 and an electrolyte solution 2a. The photocatalyst sheet 3 includes a carrier sheet having a plurality of fibers bonded thereto, and a plurality of photocatalyst particles supported or fixed on the carrier sheet. The photocatalyst particles include tungsten oxide particles, and the mass of the photocatalyst particles per unit area of ​​the photocatalyst sheet 3 is 20 g / m. 2 That's all.

[0014] The photocatalytic cell 13 is a cell that contains the electrolytic solution 2a and the photocatalytic sheet 3. The photocatalytic cell 13 may be included in a cation reduction device that reduces first cations contained in the electrolytic solution 2a to second cations by photocatalytic activity. The photocatalytic cell 13 may also be included in a device that generates hydrogen gas or oxygen gas from the electrolytic solution 2a by photocatalytic activity.

[0015] The photocatalyst cell 13 can have a light-transmitting member 5. This allows light transmitted through the light-transmitting member 5 to be irradiated onto the photocatalyst particles contained in the photocatalyst sheet 3, allowing the photocatalyst particles to have photocatalytic activity. 1, the photocatalytic cell 13 has a container 4 and a light-transmitting member 5 that closes the opening of the container 4. The light-transmitting member 5 is fixed to the container 4 by a cover 8 and a bolt 9. In addition, a buffer material 7 is provided between the light-transmitting member 5 and the cover 8, and a sealing member 6 is provided between the container 4 and the light-transmitting member 5. The photocatalytic cell 13 can have a flat shape, and the light-transmitting member 5 that serves as the light-receiving surface can be disposed on the wide surface of this flat shape.

[0016] The photocatalyst sheet 3 includes a carrier sheet and a plurality of photocatalyst particles. The photocatalyst sheet 3 can also be used in applications where at least a portion of the sheet is placed in a liquid. The photocatalyst particles are particles that become photocatalytically active when exposed to light, and are supported or fixed on a carrier sheet. The photocatalyst particles include tungsten oxide particles (WO3 particles). Tungsten oxide has a wider light absorption band than titanium oxide, and becomes photocatalytically active even when it absorbs visible light that does not contain ultraviolet light. Therefore, photocatalytic activity can be generated even when light incident on the photocatalyst cell 13 passes through the electrolyte solution 2a and then irradiates the tungsten oxide particles (photocatalyst particles). Furthermore, tungsten oxide has a larger specific gravity than titanium oxide. This allows the mass per unit area of ​​the photocatalyst sheet 3 to be increased.

[0017] The tungsten oxide particles (WO3 particles) contained in the photocatalyst particles may have a composition that deviates from the stoichiometric composition as long as they have photocatalytic activity. Furthermore, the tungsten oxide particles may contain impurity atoms or additive atoms to the extent that the photocatalytic activity is not lost. Furthermore, the photocatalyst particles may have a co-catalyst on their surface. Examples of the co-catalyst include platinum group metals such as Pt, Pd, Rh, Ru, Os, and Ir. The average particle diameter D50 of the photocatalyst particles (primary particles) contained in the photocatalyst sheet 3 is 150 nm or more, preferably 200 nm or more and 50 μm or less, and more preferably 500 nm or more and 30 μm or less.

[0018] The carrier sheet is a sheet having a plurality of fibers bonded together. The carrier sheet is, for example, paper. The fibers are plant fibers, inorganic fibers, etc. The plant fibers may be pulp fibers or cellulose. The plant fibers may also be wood pulp fibers or wood cellulose, or non-wood pulp fibers or non-wood cellulose. The inorganic fibers are glass fibers (e.g., SiO2 fibers), ceramic fibers, etc. A carrier sheet containing plant fibers can be produced, for example, as follows: Pulp extracted from a plant or the like is dispersed in water and stirred to separate it into individual plant fibers (defibration), and the defibrated plant fibers are subjected to mechanical shearing force to fluff the plant fibers (beating, fibrillation of plant fibers). The beaten plant fibers are dispersed in water, and the resulting dispersion is spread on a mesh to remove the water and form a sheet (papermaking). The papermade sheet is then pressed and dried to produce a carrier sheet. Beating the plant fibers can soften the fibers and cause fluffing (fibrillation) of the fibers, thereby strengthening the bonds between the fibers contained in the carrier sheet. A carrier sheet containing inorganic fibers can be produced, for example, by dispersing inorganic fibers in water, spreading the dispersion on a mesh, removing the water, forming a sheet (papermaking), and pressing and drying the papermade sheet. A binder can be added to the dispersion as needed.

[0019] The photocatalyst particles are supported or fixed on a carrier sheet. The photocatalyst particles may be supported or fixed on the surface of the carrier sheet, or may be supported or fixed inside the carrier sheet. Alternatively, the photocatalyst particles may be embedded in a carrier sheet having a plurality of fibrillated plant fibers (the photocatalyst particles are located between a plurality of adhered fibrillated plant fibers). This allows a large number of photocatalyst particles to be supported or fixed on the carrier sheet. Furthermore, it is possible to prevent the photocatalyst particles from detaching from the photocatalyst sheet. For example, a dispersion of beaten plant fibers and photocatalyst particles in water is spread on a mesh, the water is removed, and the resulting sheet is made into a sheet (papermaking), and the paper-made sheet is pressed and dried to produce a photocatalyst sheet 3 in which the photocatalyst particles are supported or fixed on a carrier sheet. The photocatalyst particles may also be incorporated into a carrier sheet having a plurality of inorganic fibers. For example, a dispersion of inorganic fibers and photocatalyst particles in water is spread on a mesh, the water is removed, and the sheet is formed into a sheet (papermaking), and the sheet after papermaking is pressed and dried to produce a photocatalyst sheet 3 in which the photocatalyst particles are supported or fixed on the carrier sheet. A binder can be added to the dispersion liquid as needed.

[0020] The mass of photocatalyst particles per unit area of ​​the photocatalyst sheet 3 is 20 g / m 2 or more, preferably 20 g / m 2 More than 200g / m 2 More preferably, it is 30 g / m or less. 2 More than 150g / m 2 The following is an explanation of the structure. This allows light incident on the photocatalyst cell 13 to be efficiently utilized in the photocatalytic reaction. Furthermore, the mass per unit volume of the photocatalyst sheet 3 can be increased, allowing the photocatalyst sheet 3 to be submerged in the electrolyte solution 2a. This allows the photocatalyst sheet 3, on which photocatalyst particles are supported or fixed, to be placed in the photocatalyst cell, and the electrolyte solution 2a not containing photocatalyst particles can be easily removed from the photocatalyst cell 13. Furthermore, the photocatalyst sheet 3 can be prevented from floating, moving, bending, etc., and a decrease in the light-receiving area of ​​the photocatalyst sheet 3 in the photocatalyst cell 13 can be prevented.

[0021] In the photocatalytic cell 13, the photocatalytic sheet 3 and photocatalytic particles are in contact with the electrolyte solution 2a. This allows the first cations contained in the electrolyte solution 2a to be reduced to second cations through photocatalytic activity, or the photocatalytic cell 13 can generate hydrogen gas or oxygen gas from the electrolyte solution 2a through photocatalytic activity. For example, when the photocatalytic particles are exposed to light, the first cations in the electrolyte solution 2a are reduced to second cations, and oxygen gas is generated from the electrolyte solution 2a. This can be explained as follows: Light excites electrons in the valence band of the photocatalytic particles to the conduction band, forming holes in the valence band. The electrons in the conduction band move to the surface of the photocatalytic particles, adding electrons to the first cations and reducing them to second cations (first reaction). The holes in the valence band also move to the surface of the photocatalytic particles and react with HO to generate oxygen gas (second reaction). The generated oxygen gas moves into the gas phase in the photocatalytic cell 13 and is discharged to the outside of the photocatalytic cell 13 through the oxygen gas discharge hole 12 . For example, if the primary cation is a trivalent iron ion (Fe 3+ ), and the second cation is divalent iron ion (Fe 2+ ), the following reaction is thought to proceed: 1st reaction: Fe 3+ + e - → Fe 2+ Second reaction: 2H2O → O2+ 4H + + 4e - The generated hydrogen ions (H + ) can be used in the electrolysis device 30 described below.

[0022] In the photocatalyst cell 13, the photocatalyst particles or the photocatalyst sheet 3 may be immersed in the electrolytic solution 2a. In addition, in the photocatalyst cell 13, the photocatalyst sheet 3 may be permeated with the electrolytic solution 2a. In addition, the photocatalyst sheet 3 may be placed at the bottom of the container 4.

[0023] The electrolytic solution 2a may be an aqueous solution containing first cations, which are reduced to second cations by photocatalytic activity caused by the photocatalytic particles receiving light. When the electrolytic solution 2a contains iron sulfate (FeSO4, Fe2(SO4)3), the first cation is a trivalent iron ion, and the second cation is a divalent iron ion. When the electrolyte 2a contains iron perchlorate (Fe(ClO4)3, Fe(ClO4)2), the first cation is a trivalent iron ion and the second cation is a divalent iron ion. The first and second cations may be metal complex ions, and the metal contained in the metal complex ions may be, for example, iron or cobalt.

[0024] The pH of the electrolytic solution 2a may be within a pH range in which the zeta potential of the photocatalytic particles is 0 V or higher. This generates an electrostatic attraction force that increases the probability of contact between the photocatalytic particles and the first cations, thereby increasing the probability that the first cations are reduced to second cations through photocatalytic activity. This makes it possible to produce an electrolytic solution containing a larger amount of second cations. Furthermore, by using this electrolytic solution to generate hydrogen gas in a hydrogen gas generation system described below, the efficiency of hydrogen gas generation can be improved.

[0025] When the photocatalytic particles contain tungsten oxide particles, the pH of the electrolyte 2a can be made lower than 2 (to the acidic side). This allows the zeta potential of the photocatalytic particles to be 0 V or higher, and also allows divalent iron ions and trivalent iron ions to exist stably in the electrolyte 2a. This makes it possible to prevent divalent iron ions from being oxidized to trivalent iron ions by oxygen dissolved in the electrolyte 2a, oxygen gas in the gas phase, oxygen gas generated by photocatalytic activity, and the like. For example, the pH of the electrolytic solution 2a may be adjusted by adjusting the iron sulfate concentration, iron perchlorate concentration, or the like of the electrolytic solution 2a, or the pH of the electrolytic solution 2a may be adjusted by adding an acidic substance such as sulfuric acid or perchloric acid to the electrolytic solution 2a. Furthermore, when an electrolyte solution is prepared by dissolving approximately 50 g of iron perchlorate n-hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.: n=approximately 8) in 10 L of water, the pH of the electrolyte solution will be approximately 2. The iron ion concentration of the electrolyte solution 2a is preferably, for example, 10 mmol / L to 1 mol / L. This is a concentration at which the iron ions can stably maintain their respective valence states. More preferably, the iron ion concentration of the electrolyte solution 2a is 10 mmol / L to 100 mmol / L. A lower iron ion concentration reduces the effect of iron ions on the coloring of the electrolyte solution, and can suppress a decrease in the amount of light received by the photocatalyst.

[0026] The photocatalytic cell 13 may have an inlet 10a provided to supply the electrolytic solution 2a containing the first cations into the photocatalytic cell 13, and an outlet 11a provided to discharge the electrolytic solution 2a containing the second cations from the photocatalytic cell 13. The inlet 10a and the outlet 11a may be provided so that the electrolytic solution 2a flows through the photocatalytic cell 13. This allows the first cations contained in the electrolytic solution 2a injected into the photocatalytic cell 13 from the inlet 10a to come into contact with the photocatalytic particles, and the first cations can be reduced and converted to second cations by photocatalytic activity. Furthermore, the electrolytic solution 2a containing the second cations generated by photocatalytic activity can be extracted from the photocatalytic cell 13, making it possible to utilize the electrolytic solution 2a containing the second cations.

[0027] Hydrogen Gas Generation System FIG. 2 is a schematic cross-sectional view of the hydrogen gas generation system of this embodiment. The hydrogen gas generation system 40 of this embodiment includes a photocatalytic cell 13 and an electrolyzer 30 having a cathode 16 and an anode 17. The electrolyzer 30 is configured to generate hydrogen gas from water or hydrogen ions at the cathode 16 and to oxidize second cations to first cations at the anode 17. The photocatalytic cell 13 and the electrolyzer 30 are configured to supply the electrolytic solution 2a containing the second cations generated by the photocatalytic cell 13 to the electrolyzer 30, and to supply the electrolytic solution 2a containing the first cations generated at the anode 17 to the photocatalytic cell 13.

[0028] The electrolyzer 30 may have a power supply unit configured to apply a voltage between the anode 17 and the cathode 16. The electrolyzer 30 may also have an anode chamber 22 and a cathode chamber 21 separated by an ion exchange membrane 18. The electrolytic solution 2a containing the second cations generated by the photocatalytic cell 13 is supplied to the electrolyzer 30, the anode chamber 22 is filled with the electrolytic solution 2a, and the cathode chamber 21 is filled with the electrolytic solution 2b. Then, when a voltage is applied between the anode 17 and the cathode 16 using the power supply, an anodic reaction proceeds on the surface of the anode 17, and a cathodic reaction proceeds on the surface of the cathode 16. In addition, hydrogen ions (H + ) moves through the ion exchange membrane 18 to the electrolyte 2b in the cathode chamber 21. The electrolyte 2b can be an acidic electrolyte.

[0029] At the anode 17, a reaction proceeds in which the second cations contained in the electrolyte 2a in the anode chamber 22 donate electrons to the anode 17 and are oxidized to the first cations (anode reaction). For example, if the primary cation is a trivalent iron ion (Fe 3+ ), and the second cation is divalent iron ion (Fe 2+ ), the following anodic reaction is thought to occur: Anode reaction: Fe 2+ → Fe 3+ + e -

[0030] The anode chamber 22 may have an inlet 10b provided to supply the electrolyte solution 2a containing the second cations generated in the photocatalytic cell 13 into the anode chamber 22, and an outlet 11b provided to discharge the electrolyte solution 2a containing the first cations generated from the second cations in the anode 17 from the anode chamber 22. The inlet 10b and the outlet 11b may be provided so that the electrolyte solution 2a injected from the inlet 10b passes through the anode chamber 22 and then is discharged from the outlet 11b. By circulating the electrolyte solution 2a in this manner, the anode reaction can proceed continuously and stably.

[0031] The electrolyte solution 2a containing the second cations produced in the photocatalytic cell 13 may be supplied to the anode chamber 22 of the electrolyzer 30 through a liquid supply pipe or a pump. Alternatively, the electrolyte solution 2a containing the second cations produced in the photocatalytic cell 13 may be stored in a storage tank. The electrolyte solution 2a may then be transported together with the storage tank, and the electrolyte solution 2a stored in the storage tank at the transport destination may be supplied to the anode chamber 22 of the electrolyzer 30.

[0032] The electrolyte solution 2a containing the first cations discharged from the anode chamber 22 of the electrolyzer 30 may be supplied to the photocatalytic cell 13 through a liquid transfer pipe or a pump. Alternatively, the electrolyte solution 2a containing the first cations discharged from the anode chamber 22 of the electrolyzer 30 may be stored in a storage tank. The electrolyte solution 2a may then be transported together with the storage tank, and the electrolyte solution 2a stored in the storage tank at the transport destination may be supplied to the photocatalytic cell 13. Furthermore, such a circulation system for the electrolyte solution 2a may be provided so as to add water to the circulating electrolyte solution 2a, thereby making it possible to replenish the water consumed in the second reaction described above.

[0033] At the cathode 16, the following cathode reaction proceeds in which hydrogen ions contained in the electrolyte 2b in the cathode chamber 21 receive electrons to generate hydrogen gas. Cathodic reaction: 2H + + 2e - → H2 The generated hydrogen gas is discharged to the outside of the cathode chamber 21 through the hydrogen gas discharge hole 19 and stored in the hydrogen storage tank.

[0034] The above-described anode and cathode reactions proceed at a lower applied voltage (the voltage applied between the cathode 16 and the anode 17 by the power supply unit) than in conventional water electrolysis devices. This reduces the cost of hydrogen gas production. [Explanation of symbols]

[0035] 2a, 2b: Electrolyte 3: Photocatalytic sheet 4: Container 5: Light-transmitting member 6: Sealing member 7: Cushioning material 8: Cover 9: Bolt 10a, 10b: Inlet 11a, 11b: Outlet 12: Oxygen gas outlet 13: Photocatalytic cell 16: Cathode 17: Anode 18: Ion exchange membrane 19: Hydrogen gas outlet 21: Cathode chamber 22: Anode chamber 30: Electrolyzer 40: Hydrogen gas generation system

Claims

1. A photocatalytic cell containing a photocatalytic sheet and an electrolyte, The photocatalyst sheet includes a carrier sheet having a plurality of fibers adhered thereto, and a plurality of photocatalyst particles supported or fixed on the carrier sheet; the photocatalytic particles include tungsten oxide particles, The mass of the photocatalyst particles per unit area of ​​the photocatalyst sheet is 20 g / m 2 A photocatalytic cell characterized by the above.

2. The photocatalyst cell according to claim 1, wherein the average particle diameter D50 of the photocatalyst particles contained in the photocatalyst sheet is 150 nm or more.

3. 2. The photocatalyst cell according to claim 1, wherein at least a portion of the plurality of photocatalyst particles is embedded in the carrier sheet having a plurality of fibrillated plant fibers.

4. 2. The photocatalyst cell according to claim 1, wherein at least a portion of the plurality of photocatalyst particles is embedded in the carrier sheet having a plurality of inorganic fibers.

5. The photocatalytic cell of claim 1 , wherein the pH of the electrolyte is less than 2.

6. the electrolyte solution includes a first cation; 2. The photocatalytic cell according to claim 1, wherein the electrolytic solution and the photocatalytic particles are provided so that first cations are reduced to second cations by photocatalytic activity generated when the photocatalytic particles receive light.

7. The photocatalytic cell according to claim 6, further comprising an inlet configured to supply an electrolyte solution containing a first cation into the photocatalytic cell, and an outlet configured to discharge an electrolyte solution containing a second cation from the photocatalytic cell.

8. An electrolysis device comprising the photocatalytic cell according to claim 6 or 7, and a cathode and an anode, the electrolyzer is configured to produce hydrogen gas from water or hydrogen ions at a cathode and to oxidize second cations to first cations at an anode; The photocatalytic cell and the electrolysis device are arranged to supply an electrolyte containing second cations produced in the photocatalytic cell to the electrolysis device, and the hydrogen gas generation system is arranged to supply an electrolyte containing first cations produced at the anode to the photocatalytic cell.

9. A photocatalyst sheet used for applications in which at least a portion is placed in a liquid, The photocatalyst sheet includes a carrier sheet having a plurality of fibers adhered thereto, and a plurality of photocatalyst particles supported or fixed on the carrier sheet; the photocatalytic particles include tungsten oxide particles, The mass of the photocatalyst particles per unit area of ​​the photocatalyst sheet is 20 g / m 2 That's all about the photocatalytic sheet.

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