JP2009148653A - Photocatalyst device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocatalyst device which can display photocatalytic function under exposure to light and be properly manufactured. <P>SOLUTION: This photocatalyst device 100 comprises: a base member 40 which has a plurality of projections 44 formed on at least, one surface S1 of the first surface S1 and a second surface S2 which are opposed to each other, and a third surface S3 which forms a solid by almost crossing the first surface S1 and the second surface S2, and receives an incident light; and a photocatalytic layer 42 which is formed on at least, the one surface S1 having the projections 44 and allows diffraction for irradiation with the light coming into the third surface S3 to the layer 42 by the projections 44. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photocatalytic device.

Deodorization in living and working spaces (reduction of bad odors in living, VOC (Volatile Organic Compounds) gas decomposition from new building materials), antibacterial (antibacterial properties against Escherichia coli, Staphylococcus aureus, MRSA (Methicillin-resistant Staphylococcus Aureus), etc.) For the purpose of antifouling (reducing hand dirt, fingerprints, tobacco stains, etc.), a photocatalytic device composed of a photocatalytic substance is used. The photocatalytic device is an apparatus that induces active oxygen such as superoxide anion radical (O ₂ ⁻ ) or hydroxyl radical (OH ⁻ ) by irradiating light having energy higher than the band gap. This active oxygen decomposes organic matter that causes foul odors and dirt in living spaces and work spaces into water (H ₂ O) or carbon dioxide (CO ₂ ). Can be achieved.

  As the photocatalytic substance, an oxide semiconductor such as titanium oxide is generally used. This oxide semiconductor is an ultraviolet light that exhibits a photocatalytic function when irradiated with light in the ultraviolet region (wavelength 200 nm to wavelength 360 nm). Photoresponsive photocatalytic substance. For this reason, a UV (Ultraviolet) lamp is mainly used as a light source for irradiating ultraviolet rays so as to induce active oxygen toward the photocatalytic device.

For example, a fluorescent lamp, a photocatalyst device, a lighting device, and an article that can effectively obtain a photocatalytic action even in a low-temperature atmosphere have been proposed (see, for example, Patent Document 1).
On the other hand, among light sources for emitting ultraviolet rays such as UV lamps, there are many that emit light in the visible light region (for example, wavelength 380 nm to wavelength 770 nm), that is, visible light. When such a light source is used, effective use of visible light is desired from the viewpoint of energy use efficiency. Therefore, as in the photocatalyst device 500 shown in FIG. 7, the photocatalytic function can be achieved by irradiating not only ultraviolet rays but also natural light (sunlight) or visible light emitted from an inexpensive light source (general fluorescent lamp or incandescent lamp). A photocatalytic device using a visible light responsive photocatalytic substance that can be exhibited has been developed.
JP-A-9-129184 (page 1-2, FIG. 1-13)

  By the way, when a UV lamp is used as a light source for a photocatalyst device, the UV lamp is disadvantageous in terms of economy because it has a short life and a relatively high cost. In general, the photocatalyst apparatus is passively used in order to exhibit the photocatalytic function after waiting for light irradiation. On the other hand, when UV light is actively irradiated by a UV lamp and the photocatalytic function is exerted, since the conversion efficiency to light energy is low, unnecessary energy is consumed as long as the irradiation time of ultraviolet light continues. It will end up.

  On the other hand, when natural light is used as a light source for a photocatalyst device, uncertainties due to natural phenomena are steadily ceased. For example, natural light having an energy exceeding a band gap sufficient to exert a photocatalytic function cannot be obtained.

  As described above, even when a UV lamp is used or when natural light is used, it is difficult to use as a light source for a photocatalytic device.

  In the photocatalyst device of the present invention for solving the above-described problem, at least one of the first surface and the second surface facing each other has a plurality of protrusions, and the first surface and the first surface A base member on which light is incident on a third surface that forms a solid substantially orthogonal to the surface of 2, and is provided on at least one surface side having the plurality of protrusions and is incident on the third surface And a photocatalyst layer irradiated with the diffracted light diffracted by the plurality of protrusions.

  ADVANTAGE OF THE INVENTION According to this invention, the photocatalyst apparatus which exhibits a photocatalytic function by light irradiation is appropriately realizable.

[Example 1]
<<< Configuration of photocatalyst device >>>
The photocatalyst device 100 according to an embodiment of the present invention is not passively used to exhibit the photocatalytic function after waiting for natural incident of visible light. It is used in such a way that it actively exerts the photocatalytic function. Specifically, active oxygen is induced in the photocatalyst layer 42 by laser light in the visible light region irradiated by the laser light source 10, and the organic matter floating in the airflow in the living space or the working space is water (H _2). The purpose of deodorizing, antibacterial, and antifouling can be achieved by decomposing into O) or carbon dioxide (CO ₂ ). Such a photocatalytic device 100 is suitable as a member mounted on an air cleaner, a humidifier, an air conditioner, or the like.

  As shown in the plan view shown in FIG. 1A and the side view shown in FIG. 1B, the configuration of the photocatalyst device 100 includes a laser light source 10, cylindrical lenses 20 and 30 for generating sheet light SL, and a photocatalyst layer. 42 is configured to include, for example, a base member 40 provided by being laminated or the like. Hereinafter, the configuration of the photocatalyst device 100 will be sequentially described with reference to FIG. 1 and FIG. 3 as appropriate. 2 is a diagram illustrating a manufacturing process of a base member 40 having an embossed structure, which will be described later, and FIG. 3 is a diagram illustrating an optical system that generates sheet light SL, which will be described later. The XYZ coordinate axes shown in FIGS. 1A and 1B have the normal direction of the lower surface S2 from the lower surface S2 toward the upper surface S1 as the positive direction of the Z axis, and the normal line of the side surface S3 from the side surface S3 toward the side surface S5. The direction is the positive direction of the X axis, and the normal direction of the side surface S4 from the side surface S4 to the side surface S6 is the positive direction of the Y axis. The same applies to the XYZ coordinate axes shown in FIG.

=== Photocatalyst layer ===
The photocatalyst layer 42 constituting a part of the photocatalyst device 100 will be described.
The photocatalyst layer 42 is composed of a visible light responsive photocatalytic substance having high photocatalytic activity in a visible light region (for example, a wavelength of 380 nm or more and less than 780 nm, a reference wavelength exceeding 400 nm and 770 nm or less). The visible light responsive photocatalytic substance is an anatase type, a rutile type, or an ultraviolet responsive photocatalytic substance mainly composed of titanium oxide (TiO ₂ ), which is a mixed crystal thereof, with an oxygen atom ( O) a part of which is substituted with a nitrogen atom (N), a nitrogen atom doped between lattices of the crystal, a nitrogen atom arranged at the grain boundary of the polycrystalline aggregate of the crystal, at least Consists of one or more types.

UV-responsive photocatalyst materials as the base material of the visible-light-responsive photocatalytic material, in addition to titanium oxide described above, tungsten oxide (WO _3), iron oxide (Fe 2 O _3), zinc oxide (ZnO), titanate Various oxides such as strontium (SrTiO ₃ ) and niobium oxide (Nb ₂ O ₃ , Nb ₂ O ₅ ), sulfides such as cadmium sulfide (CdS) and zinc sulfide (ZnS), or gallium phosphide (GaP), You may comprise at least 1 or more types of components among gallium arsenide (GaAs), cadmium selenide (CdSe), etc. Furthermore, noble metals such as platinum (Pt), palladium (Pd), gold (Au), transition metals such as nickel (Ni), chromium (Cr), copper (Cu), cobalt (Co), lanthanum (La), At least one kind of rare earth elements such as cerium (Ce), praseodymium (Pr), neodymium (Nd), dysprosium (Dy), holmium (Ho), erbium (Er), and lutetium (Lu) may be combined. This is known to further improve the photocatalytic activity.

  In this embodiment, as described above, a visible light responsive photocatalyst material such as an ultraviolet responsive photocatalyst material is composed of titanium oxide having a high photocatalytic activity as a main component. Since titanium oxide does not dissolve in water, the visible light responsive photocatalytic substance is mixed with alcohol or the like and heat treated to form the photocatalytic layer 42 on the base member 40. The photocatalyst layer 42 may be a single layer, for example, or may be a laminate having a plurality of layers.

=== Embossed structure (uneven structure) ===
As shown in FIGS. 1A and 1B, the base member 40 is substantially orthogonal to the upper surface S1 (first surface) and the lower surface S2 (second surface) facing each other and parallel to the upper surface S1 and the lower surface S2. It has a plurality of (four) side surfaces S3 to S6 (third surface) surrounding the upper surface S1 and the lower surface S2, and includes a substantially plate-like main body having a rectangular parallelepiped shape, for example. In addition, although the transparent glass material is employ | adopted as a raw material of the base member 40 in this embodiment, what is necessary is just a material which permeate | transmits light, such as an acrylic material.

  The upper surface S1 of the base member 40 is provided with, for example, an embossed structure (concave / convex structure) having a plurality of protrusions 44 disposed over the entire surface. In this case, in view of the strength in the thickness direction (Z-axis direction) of the base member 40, the lower surface S2 of the base member 40 is fixed with a hard plate-like material, thereby increasing the strength in the thickness direction. It is preferable to do this. The protruding portion 44 is formed as a protruding portion 44 having a substantially cylindrical shape, for example. As described above, the surface area of the base member 40 that forms the photocatalyst layer 42 is increased by the unevenness of the plurality of protrusions 44 by, for example, the embossed structure having the plurality of protrusions 44 provided on the upper surface S1 of the base member 40. The photocatalytic activity per unit area can be improved. Of course, even if the photocatalyst layer 42 is formed by providing the plurality of protrusions 44 on the lower surface S2 instead of the upper surface S1 of the base member 40, the same effect as described above can be obtained.

  For example, the embossed structure can be realized by a so-called electroforming technique capable of high-precision fine processing. FIG. 2 is a diagram for explaining a manufacturing process of, for example, an embossed structure by the electroforming technique. As shown in the figure, first, a prototype model 142 of the base member 40 having an uneven structure such as an embossed structure is manufactured, and further, a basin model 144 serving as an electroforming mother mold is manufactured based on the prototype model 142. Then, after pretreatment such as applying a conductive member 146 to the surface of the tank model 144, it is placed in the electroforming tank 150 containing the electrolyte solution and subjected to electroforming. The electroforming process is a process in which a current is passed through an electrolyte solution containing ions of a target metal (in this case, a glass material) to deposit the target metal on the surface of the bathing model 144. . As a result of executing this electroforming process, the base member 40 is formed by being assembled into the tank model 144. And the base member 40 of an embossed structure is obtained by separating the base member 40 from the tank model 144, for example.

=== Light source ===
In the case of a method in which the photocatalytic device 100 is positively irradiated with UV lamp light, useless energy is lost due to poor efficiency. Therefore, in the present embodiment, in order to compensate for this drawback, laser light (LASER: light amplification by stimulated emission of radiation) and / or low cost, long life, and high energy conversion efficiency compared with the conventional UV lamp and / or Or the light source 10 of LED light (LED: light emitting diode) is employ | adopted as a light source which irradiates the photocatalyst apparatus 100. FIG. From the viewpoint of energy conversion efficiency, blue-violet laser light (for example, a wavelength of 380 nm to 450 nm, which is adopted in the “HD DVD” (registered trademark) standard and the “Blu-ray Disc” (registered trademark) standard of next-generation optical disks, A blue-violet semiconductor laser element emitting a reference wavelength of 405 nm is preferable. Alternatively, in consideration of the balance between energy conversion efficiency and cost, a red semiconductor laser element that emits red laser light (wavelength 630 nm to wavelength 685 nm) used in the “DVD” (registered trademark) standard, or “CD” ( An infrared semiconductor laser element that emits infrared laser light (wavelength 765 nm to wavelength 830 nm) used in the “Compact Disc” (registered trademark) standard may be used. Further, for example, it may be an LED light emitting element that emits any region wavelength in the wavelength band of 380 nm to 830 nm, or an LED light emitting element that emits any region wavelength in the band exceeding the reference wavelength of 400 nm and not more than 770 nm. .

=== Sheet light ===
The light emitted from the light source 10 is incident on any one of the plurality (four) side surfaces S3 to S6 of the base member 40. In the case of the present embodiment, the side surface S3 of the base member 40 is used as the light incident surface, and the light emitted from the light source 10 is deformed (shaped) into the sheet light SL (band-shaped light flux), and then the side surface S3 of the base member 40 is used. It is necessary to make it incident on. Therefore, as shown in FIGS. 1A, 1B, and 3, a plurality of (two) cylindrical lenses 20 and 30 (first lens and second lens) are combined to transform light into sheet light SL. The optical system is provided between the light source 10 and the base member 40. FIG. 3 shows a case where a space exists between the light source 10, the two cylindrical lenses 20 and 30, and the base member 40 for the convenience of explaining the generation of the sheet light. In order to make the photocatalytic device compact and to effectively use light, as shown in FIGS. 1A and 1B, the light source 10, the two cylindrical lenses 20, 30 and the base member 40 are each fixed by an adhesive or It is integrated using auxiliary parts.

  More specifically, the cylindrical lenses 20 and 30 are lenses having a shape obtained by dividing a cylinder into two in the direction of the cylinder axis and having a curvature only in one direction. In the case of this embodiment, as shown in FIG. 3, light from the light source 10 is incident on the cross section (plane) of the cylindrical lens 20. With this arrangement, the cylindrical lens 20 has a function of expanding the laser light emitted from the light source 10. On the other hand, the cylindrical lens 30 is arranged so that its curved surface faces the curved surface of the cylindrical lens 20. With this arrangement, the cylindrical lens 30 has a function of deforming the light expanded by the cylindrical lens 20 into the sheet light SL. Note that the width H and the thickness T of the sheet light SL can be adjusted to any length according to the side surface S3 of the base member 40 by changing the focal lengths and the arrangement of the cylindrical lenses 20 and 30. .

  As described above, according to the present embodiment, by adopting the sheet light SL, a simple optical system and a minimum focal length can be realized, and the photocatalytic device 100 can be made compact. As an optical system for generating the sheet light SL, in addition to the method using the cylindrical lenses 20 and 30 as described above, for example, a polygon mirror or a galvano mirror is used to shake the light with the mirror, and the space is made. A method of scanning and generating the sheet light SL in a pseudo manner may be employed.

=== Fresnel diffraction ===
When the sheet light SL is incident on the side surface S3 of the base member 40, the sheet light SL travels from the side surface S3 of the photocatalyst device 100 toward the side surface S5 (the positive direction of the X axis). In the course of this sheet light SL, Fresnel diffraction is induced when the light SL passes through the vicinity of the base portion on the lower surface S2 side of each protrusion 44 of the embossed structure provided on the upper surface S1. For example, the sheet light SL traveling from the side surface S3 toward the side surface S5 is diffracted by the plurality of protrusions 44, for example, from the lower surface S2 side to the upper surface S1 side of the base member 40. As a result, for example, diffracted light (planar light flux) by the plurality of protrusions 44 is irradiated to the photocatalyst layer 42 covering the plurality of protrusions 44, and active oxygen is induced in the photocatalyst layer 42. For example, the base member 40 functions as a surface light emitter that irradiates the planar light beam from the upper surface S <b> 1 toward the photocatalytic layer 42.

  Further, in the progress of the sheet light SL traveling from the side surface S3 to the side surface S5 (the positive direction of the X axis) of the photocatalyst device 100, the vicinity of the root portion of each projection 44 of, for example, the embossed structure provided on the upper surface S1 When the light SL passes, for example, Fresnel diffraction is induced. For example, the sheet light SL traveling from the side surface S3 toward the side surface S5 is diffracted in the direction on the upper surface S1 side (substantially the positive direction of the Z axis) by the root portions of the plurality of protrusions 44. As a result, for example, diffracted light from the plurality of protrusions 44 is irradiated to the photocatalyst layer 42 covering the plurality of protrusions 44, and active oxygen is induced in the photocatalyst layer 42.

  As described above, for example, by using Fresnel diffraction due to an uneven structure such as an embossed structure, it is not necessary to provide a special optical system when irradiating the photocatalyst layer 42 with light, and the photocatalytic device 100 can be made compact. can do.

[Example 2]
=== Double-sided type ===
FIG. 4 is a side view of the double-sided photocatalyst device 102 in which the protrusions 44 are provided on both the upper surface S1 and the lower surface S2 of the base member 40 to form the photocatalyst layer 42. The XYZ coordinate axes shown in FIG. 4 have the same definition as the XYZ coordinate axes shown in FIGS. 1A and 1B. By adopting the double-sided photocatalyst device 102, the single-sided surface on which the protrusion 44 is provided only on one surface (one surface) of the upper surface S1 or the lower surface S2 of the base member 40 as shown in FIG. Compared with the mold, the photocatalytic activity per unit area can be further improved.

[Example 3]
=== Hexagonal column type ===
FIG. 5 is a diagram showing a configuration of a hexagonal column type photocatalyst device 200. The XYZ coordinate axes shown in FIG. 5 are defined as the Z axis positive direction on the paper surface in FIG. 5 and the X axis positive direction on the paper right direction in FIG. Is the positive direction of the Y-axis.

  The photocatalyst device 200 includes a light source 205 similar to the light source 10, a hexagonal cylinder outer wall surface having a fine embossed structure, a hexagonal cylinder inner wall surface, an upper surface and a lower surface substantially orthogonal to the wall surfaces, and a hexagonal cylinder. The base member 210 having a mold structure, the photocatalyst layer 220 formed on the outer wall surface of the hexagonal column of the base member 210, and the photocatalyst layer 230 formed on the inner wall surface of the hexagonal column of the base member 210 are configured. Note that the fine embossed structure may be provided on only one of the outer wall surface of the hexagonal column or the inner wall surface of the hexagonal column, but the photocatalytic activity per unit area can be improved by providing it on both wall surfaces.

  When using the photocatalyst device 200, in order to obtain natural convection, the prismatic axis of the base member 210 is disposed so as to be perpendicular to the horizontal plane (a plane parallel to the X axis). The light source 205 is arranged so that light emitted from the light source 205 is incident from the upper surface (surface in the positive direction of the Z axis) or the lower surface (surface in the negative direction of the Z axis) of the base member 210. With such an arrangement, light incident from the light source 205 on one of the upper surface and the lower surface of the base member 210 via an optical system (not shown) travels while being totally reflected inside the base member 210. In this progressing process, for example, a fine emboss structure is formed on the inner wall surface of the hexagonal column and the outer wall surface of the hexagonal column of the base member 210, so that Fresnel diffraction is induced. Then, light is irradiated from the base member 210 toward the photocatalyst layer 220 on the outer wall surface side and the photocatalyst layer 230 on the inner wall surface side, and active oxygen is induced in the photocatalyst layer 230.

  As described above, the photocatalyst device 200 according to the third embodiment that exhibits the photocatalytic function by light, as in the photocatalyst devices 100 and 102 described above, is simple and includes the light source 205, the base member 210, and the photocatalyst layers 220 and 230. In addition, it can be realized with a compact configuration. Moreover, since the natural convection which circulates through the cavity is obtained by the cavity which exists in the hexagonal column inner wall surface side of the base member 210, the photocatalyst apparatus 200 can improve the utilization efficiency of a photocatalyst function more.

[Example 4]
=== Cylindrical type ===
FIG. 6 is a diagram showing a configuration of a cylindrical photocatalytic device 300. Note that the XYZ coordinate axes shown in FIG. 6 have the same definition as the XYZ coordinate axes shown in FIG.

  The photocatalyst device 300 has basically the same mechanism as the hexagonal column type photocatalyst device 200 except for a cylindrical structure. For example, light incident from the light source 305 to one of the upper surface and the lower surface of the columnar base member 310 through an optical system (not shown) travels while being totally reflected inside the base member 310. In this progression, Fresnel diffraction is induced because, for example, a fine emboss structure is formed on the inner wall surface and the outer wall surface of the cylinder of the base member 310. Then, light is irradiated from the base member 310 toward the photocatalyst layer 320 on the outer wall surface side and the photocatalyst layer 330 on the inner wall surface side, and active oxygen is induced in the photocatalyst layer 320. As with the hexagonal column type photocatalyst device 200, the fine embossed structure may be provided on only one of the outer wall surface of the cylinder or the inner wall surface of the cylinder, but the photocatalyst per unit area is provided on both wall surfaces. The activity can be improved.

  As described above, the photocatalyst device 300 according to the fourth embodiment that exhibits the photocatalytic function by light as in the above-described photocatalyst devices 100 and 102 is simple and includes the light source 305, the base member 310, and the photocatalyst layers 320 and 330. In addition, it can be realized with a compact configuration. Moreover, since the photocatalytic device 300 can obtain natural convection circulating through the cavity by the cavity existing on the cylindrical inner wall surface side of the base member 310, like the hexagonal column type photocatalytic device 200, the utilization efficiency of the photocatalytic function is further improved. Can be improved.

=== Other three-dimensional structure ===
In addition to the hexagonal column type and the cylindrical type described above, for example, a polygonal column type other than a hexagonal column such as a triangular column type and a quadrangular column type, and various types that allow natural convection by penetrating a sphere or cone vertically. These three-dimensional structures can be employed as the base member of the photocatalytic device.

<<< Other Embodiments of Photocatalyst Apparatus >>>
As mentioned above, although embodiment of this invention was described, embodiment mentioned above is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. The present invention can be changed / improved without departing from the gist thereof, and the present invention includes equivalents thereof.

It is a top view of the photocatalyst device concerning a first embodiment of the present invention. It is a side view of the photocatalyst device concerning a first embodiment of the present invention. It is a figure which shows the manufacturing process of the base | substrate member with the embossing structure which concerns on 1st embodiment of this invention. It is a figure which shows the optical system for producing | generating the sheet | seat light concerning 1st embodiment of this invention. It is a side view of the photocatalyst device concerning a second embodiment of the present invention. It is a figure which shows the structure of the photocatalyst apparatus which concerns on 3rd embodiment of this invention. It is a figure which shows the structure of the photocatalyst apparatus which concerns on 4th embodiment of this invention. It is a figure for demonstrating the function of the conventional photocatalyst apparatus.

Explanation of symbols

10, 205, 305 Light source 20 Cylindrical lens (first lens)
30 Cylindrical lens (second lens)
40, 210, 310 Base member 42, 220, 230, 320, 330 Photocatalyst layer 44 Projection (projection)
100, 102, 200, 300, 500 Photocatalyst device 142 Prototype model 144 Entrance tank model 146 Conductive member 150 Electroforming tank S1 Upper surface (first surface)
S2 Lower surface (second surface)
S3, S4, S5, S6 Side surface (third surface)
SL sheet light (light)

Claims (6)

A third surface on which at least one of the first surface and the second surface facing each other has a plurality of protrusions and forms a solid substantially orthogonal to the first surface and the second surface. A base member on which light is incident,
A photocatalyst layer that is provided on at least the one surface side having the plurality of protrusions, and is irradiated with the light incident on the third surface diffracted by the plurality of protrusions;
A photocatalytic device comprising:   2. The photocatalytic device according to claim 1, wherein the plurality of protrusions are provided on both the first surface and the second surface. 3.   3. The photocatalytic device according to claim 1, wherein the light is laser light and / or LED light. 4. In the photocatalyst device according to any one of claims 1 to 3,
A first lens that expands the light emitted from the light source between the light source that emits the light and the base member, and a second lens that transforms the light expanded by the first lens into sheet light. A lens, and
The base member includes a substantially plate-shaped main body having the first surface, the second surface, and the plurality of third surfaces, and one of the plurality of third surfaces. The sheet light is incident;
A photocatalytic device characterized by the above. In the photocatalyst device according to any one of claims 1 to 3,
The base member has two outer surfaces substantially orthogonal to the polygonal column outer wall surface, the second surface to the polygonal column inner wall surface, the third surface to the polygonal column outer wall surface, and the polygonal column inner wall surface. A photocatalytic device having a polygonal cylindrical structure as a surface, wherein the light is incident on at least one of the two surfaces. In the photocatalyst device according to any one of claims 1 to 3,
The base member is a cylinder having the first surface as a cylindrical outer wall surface, the second surface as a cylindrical inner wall surface, and the third surface as two surfaces substantially orthogonal to the cylindrical outer wall surface and the cylindrical inner wall surface. The photocatalytic device is characterized in that the light is incident on at least one of the two surfaces.

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