JP2008264758A - Visible light responsive type photocatalyst synthetic method, photocatalytic material, photocatalyst coating compositions, and photocatalyst body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a tungsten oxide visible light responsive type photocatalyst synthetic method enabling a remarkable improvement in photocatalytic performance, and a photocatalyst body. <P>SOLUTION: The visible light responsive type photocatalyst synthetic method comprises a step of sublimating or burning metal tungsten, and of synthesizing tungsten oxide particles having a crystal structure in which a peak intensity of (200) surface appears most strongly by an XRD analysis. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a visible light responsive photocatalyst synthesis method including tungsten oxide as a main component, a visible light responsive photocatalyst material, a visible light responsive photocatalyst coating material, and a visible light responsive photocatalyst.

  Currently, titanium oxide is mainly used as a photocatalytic material. Titanium oxide photocatalysts are widely used in antifouling, deodorant and other applied products, but they have the property of being excited by ultraviolet rays, so there is a problem that sufficient photocatalytic performance cannot be obtained for indoor applications where ultraviolet rays are low. is there. As a countermeasure, a so-called visible light responsive photocatalyst has been actively researched and developed. Specifically, a type in which titanium oxide is doped with nitrogen and a type in which platinum is supported on titanium oxide have been developed. However, since this type of photocatalyst has a wavelength range of 400 to 410 nm of main excitation light, the photocatalytic performance is insufficient for indoor illumination light.

Further, tungsten oxide and iron oxide have been studied as a visible light responsive photocatalyst. Tungsten oxide has a band gap of 2.5 eV and a yellow color, and is an advantageous material when applied to building materials. In addition, the material is less harmful and relatively inexpensive. In addition, the photocatalytic effect by visible light of tungsten oxide is recognized by the film | membrane produced by the reactive sputtering method (patent document 1 or nonpatent literature 1).
JP 2001-152130 A “Photocatalyst”, NT, S, May 27, 2005, p676).

  Tungsten oxide is stable in the atmosphere at room temperature, but this tungsten trioxide has a complicated crystal structure and is easily changed. Normally, tungsten trioxide made from para-tungsten ammonium, ammonium methanetungstate, and tungstic acid is monoclinic, but the crystal structure easily changes due to stress during processing of the powder and changes to triclinic. (J. Solid State Chemistry 143, 2432 (1999)). In the photocatalyst, electrons and holes excited by light need to move to the surface, and there are few defects that become recombination centers in the crystal, and it is necessary to make the particles small.

Conventionally, sufficient photocatalytic effect could not be obtained with tungsten oxide powder because the crystal change partially occurred during processing in the powder pretreatment, and different crystals were mixed. This is thought to be due to a defect that causes bonding. The commercially available WO ₃ fine particles have a large particle size of 1 to 100 μm, and it is necessary to carry out a dispersion treatment with a ball mill or a bead mill in order to make the WO ₃ photocatalyst powder into a paint. However, there is also a problem that when the dispersion treatment is performed, the catalytic activity is reduced and a highly active paint cannot be obtained.
The present invention has been made to solve these problems, and provides a visible light responsive photocatalyst synthesis method, a visible light responsive photocatalyst, and a visible light responsive photocatalyst coating that can greatly improve the photocatalytic performance. With the goal.

(1) The visible light responsive photocatalytic synthesis method (first invention) according to claim 1 is an oxidation having a crystal structure in which metal tungsten is sublimated or burned and the peak intensity of (200) plane is the strongest by XRD analysis. It is characterized by synthesizing tungsten fine particles.
(2) The visible light responsive photocatalytic synthesis method according to claim 2 is characterized in that, in the above (1), tungsten oxide fine particle fumes generated by sublimation or combustion of metallic tungsten are collected.
(3) The visible light responsive photocatalytic synthesis method according to claim 3 is characterized in that, in the above (2), the tungsten oxide fine particle fume is passed through an electric furnace of 600 to 1000 ° C. in an oxidizing atmosphere.
(4) The visible light responsive photocatalyst material according to claim 4 is characterized by comprising tungsten oxide fine particles having a crystal structure in which the peak intensity of the (200) plane is the strongest as measured by XRD analysis.

(5) In the visible light responsive photocatalytic material according to claim 5, in the above (4), the tungsten oxide fine particles contain a larger amount of cubic crystal structure particles than other crystal structure particles. It is characterized by being.
(6) The visible light responsive photocatalytic material according to claim 6 is characterized in that, in the above (4) or (5), the average particle diameter of the tungsten oxide fine particles is 0.01 to 0.1 μm or less. However, a preferable average particle diameter is 0.01 to 0.05 μm. Here, if the average particle diameter is less than 0.01 μm, the dispersibility of the fine particles is lowered, making it difficult to form a paint.

(7) The visible light responsive photocatalytic material according to claim 7 is characterized in that, in the above (6), at least a cubic crystal structure is included.
(8) The visible light responsive photocatalytic material according to claim 8 is characterized in that, in the above (7), in addition to cubic crystal structure particles, at least of monoclinic and triclinic crystal structure particles Any particle is included.
(9) The visible light responsive photocatalyst material according to claim 9 is characterized in that the visible light responsive photocatalyst material according to any one of (4) to (8) is dispersed in pure water. . Here, since tungsten oxide has a property of being dissolved in an alkaline solution, pure water is used as a neutral dispersion medium in order to obtain a stabilized coating material.

(10) The visible light responsive photocatalyst paint according to claim 10 is characterized in that, in the above (9), the photocatalyst material is subjected to a dispersion treatment with ultrasonic waves of 40 to 120 kHz. However, although it varies depending on the ultrasonic output conditions and time conditions, a frequency of 60 to 100 kHz is preferable. Here, if the frequency is less than 40 kHz, the agglomerated fine particles cannot be efficiently dispersed, and 120 kHz is a limit frequency of commercially available products.
(11) The visible light responsive photocatalyst material according to claim 11 includes the visible light responsive photocatalyst material according to any one of (4) to (8) above, and is a metal of any one of Al, Zr, and Si An oxide binder or a composite oxide binder of Al—Si is contained in an amount of 1 to 10% by mass with respect to the visible light responsive photocatalyst medium. Here, when the binder is less than 1% by mass, the strength as a coating film is insufficient, and when it exceeds 10% by mass, the photocatalytic activity is weakened.

  (12) The visible light responsive photocatalyst according to claim 12 is characterized in that a photocatalytic film is formed by applying the visible responsive photocatalyst paint according to any one of (9) to (11) above. . Examples of the photocatalyst of the present invention include those having a structure in which the photocatalyst coating is applied to the substrate surface to form a photocatalyst film. Here, examples of the photocatalyst include tube products such as fluorescent lamps, building materials such as window glass, mirrors, and tiles, sanitary products, filter parts for air conditioners and deodorizers, and optical devices. Applications and categories are not limited to these.

  According to the present invention, tungsten oxide particles obtained by sublimating or burning metallic tungsten are synthesized with tungsten oxide fine particles having a crystal structure in which the peak intensity of the (200) plane is the strongest by XRD analysis. The visible light responsive photocatalyst synthesis method, visible light responsive photocatalyst, and visible light responsive photocatalyst coating can be obtained.

Hereinafter, specific embodiments of the present invention will be described.
(First embodiment)
FIG. 1 shows a schematic view of an apparatus for synthesizing tungsten oxide. Reference numeral 1 in the drawing indicates a tungsten wire spool (hereinafter referred to as a spool) that feeds out a metal tungsten wire 2. The metal tungsten wire 2 is heated and burned by the gas burner 3 to become fumes 4 of tungsten oxide fine particles. The fume 4 is collected by a fume suction pipe 6 provided in an electric dust collector 5 as a collection device. A part of the fume suction pipe 6 is disposed in the electric furnace 7.

First, a metal tungsten wire is heated by a burner at about 1000 to 1700 ° C. for a short time (5 to 15 seconds per 1 cm). As a result, the metallic tungsten is sublimated by burning and rapidly oxidized to release fumes of tungsten trioxide (WO ₃ ) fine particles to the atmosphere. The generated fumes contain three or more types of cubic, triclinic and monoclinic, and contain triclinic rich ultrafine particles of 0.07 to 0.1 μm. Next, this fume is collected by an electric dust collector to obtain WO ₃ fine particles. Subsequently, in order to suppress the crystal grain growth of the WO ₃ fine particles and to change the crystal structure from the triclinic system to the cubic system or the monoclinic system, the fume was introduced into an electric furnace in an oxidizing atmosphere of 600 to 1000 ° C. Then, heat treatment is performed in a short time to synthesize highly active tungsten oxide fine particles.

According to the first embodiment, it is possible to obtain a tungsten oxide visible light responsive photocatalyst body excellent in photocatalytic performance in which more fine particles having a cubic crystal structure are contained than fine particles having other crystal structures. Note that when collecting fumes of WO ₃ fine particles by the electrostatic precipitating method, there is no clogging of the filter or mixing of filter components, compared with the case of collecting using a HEPA filter or the like. It can be easily recovered, and the suction conditions, speed and amount of the recovery device can be easily adjusted, and desired WO ₃ ultrafine particles having stable activity can be obtained.

  FIG. 2 shows a schematic diagram of a measuring apparatus for an acetaldehyde gas decomposition test. Reference numeral 8 in the figure indicates a measuring container having a capacity of 3000 cc, in which a watch glass 9 containing photocatalyst powder (mass: 0.1 g) is arranged, and a fan 10 is arranged below it. In addition, a white LED (using NSPW500BS) as the light source 11 is disposed on the upper portion of the measurement container 8. A multi-gas monitor 12 as a measuring instrument is connected to the measurement container 8 via a pipe 13. Note that 10 ppm of acetaldehyde is used as the introduced gas.

  When the tungsten trioxide fine particles were subjected to the acetaldehyde gas decomposition test using the measurement apparatus of FIG. 2, the characteristic diagram shown in FIG. 3 was obtained. The line a in FIG. 3 is a monoclinic system rich tungsten oxide fine particle photocatalyst, the line b is a cubic type rich tungsten oxide fine particle photocatalyst according to the above embodiment, and the line c is a photocatalyst arranged in a measurement vessel. Indicates no case.

  Moreover, when the tungsten oxide microparticle photocatalyst according to the first embodiment was subjected to XRD (X-ray diffraction) analysis, a chart as shown in FIG. 4A was obtained. Here, FIG. 4A is a chart of measurement results based on XRD analysis, and shows the relationship between intensity (CPS) and angle 2θ (degrees). 4B shows monoclinic data, and FIG. 4C shows cubic data. From FIG. 4, it can be seen that the peak intensity of the (200) plane is the strongest as indicated by the arrow X.

Note that the peak intensity of the (200) plane was the strongest, as is apparent from the characteristic diagram of FIG. 5 in which the strength characteristics were measured by varying the sublimation temperature with a burner. In FIG. 5, line a shows an XRD chart of commercially available WO ₃ fine particles, and line b shows an XRD chart of WO ₃ fine particles without heating after fume recovery. According to FIG. 5, the heating temperature for suppressing the crystal grain growth of the WO ₃ fine particles and changing the crystal structure from the triclinic system to the cubic system or the monoclinic system was changed from 600 to 1000 ° C. It was clear that the peak intensity was strongest on the (200) plane, and photocatalytic activity was observed by irradiation with visible light.

(Second Embodiment)
First, a metal tungsten wire is heated by a burner at about 1000 to 1700 ° C. for a short time (5 to 15 seconds per 1 cm). As a result, the metallic tungsten is sublimated by burning and rapidly oxidized to release fumes of tungsten trioxide (WO ₃ ) fine particles to the atmosphere. The generated fumes contain three or more types of cubic, triclinic and monoclinic, and contain triclinic rich ultra fine particles of 0.03 to 0.1 μm. Next, this fume is collected by an electric dust collector to obtain WO ₃ fine particles. Subsequently, in order to suppress the crystal grain growth of the WO ₃ fine particles and to change the crystal structure from the triclinic system to the cubic system or the monoclinic system, the fume was introduced into an electric furnace in an oxidizing atmosphere of 600 to 1000 ° C. Then, heat treatment is performed in a short time to synthesize highly active WO ₃ fine particles.

  According to the second embodiment, the same effect as in the first embodiment can be obtained. Further, when the tungsten oxide fine particles are further advanced, the particles progress to a particle diameter of 10 to 20 nm, but the ultrafine particles have a cubic structure. Further, the further micronization improves the specific surface area of the photocatalyst powder and improves the photocatalytic decomposition activity.

(Third embodiment)
The WO ₃ fine particles synthesized in the second embodiment are mixed with pure water, and ZrO ₂ as a metal oxide binder is added as a solid component in an amount of about 10 to 20% by mass with respect to the WO ₃ fine particles. Dispersion treatment was performed with ultrasonic waves to obtain a visible light responsive photocatalytic coating.
According to the third embodiment, the agglomerated WO ₃ fine particles can be efficiently dispersed by performing dispersion treatment with ultrasonic waves of a specific frequency. In fact, when the dispersion state was examined when the frequency was changed to 100 kHz and 60 kHz with the same time, the result shown in FIG. 6 was obtained. It can be seen from FIG. 6 that the dispersion state also changes depending on the ultrasonic frequency. In particular, it is clear that the higher the frequency, the better the dispersion situation than the lower frequency. In addition, although the test by the physical dispersion process was also performed in the meaning compared with the dispersion process by ultrasonic waves, it was confirmed that the physical dispersion process changed from a highly active state to a worse one.

(Fourth embodiment)
The photocatalyst powder according to the fourth embodiment was prepared as follows.
First, it was pulverized with a paratungsten ammonium salt (APT) bead mill or a planetary mill, and classified by centrifugation. Next, this fine particle is heat-treated in the atmosphere at 400 to 600 ° C., whereby a photocatalyst powder having an average particle diameter of 0.01 to 0.1 μm and comprising tungsten trioxide fine particles can be purified. In the present embodiment, by performing heat treatment at about 500 ° C. in the atmosphere, tungsten trioxide fine particles having strong peaks of (002) plane and (100) plane can be obtained by XRD analysis with an average particle diameter of 0.05 μm. did it. It has been found that the heat treatment causes a slight crystal growth to increase the grain size.

That is, when XRD data of WO ₃ photocatalyst fine particles (average particle diameter: 0.01 to 0.1 μm) was examined, characteristic diagrams as shown in FIGS. 7A and 7B, for example, were obtained. (A) in FIG. 7 is synthesized by the same method as in this embodiment except that heat treatment is not sufficiently performed, and a monoclinic crystal (002) in the vicinity of a predetermined angle 2θ (degrees). ) Plane and monoclinic (200) plane have high peak intensity. FIG. 7B shows the WO ₃ photocatalyst fine particles of the present embodiment. The monoclinic (002) plane has a high peak intensity in the vicinity of the same angle 2θ as in FIG. 7A, and is higher than this plane. It has a peak intensity of cubic (100) plane of peak intensity.

Further, various samples were prepared, and the gas decomposition activity of WO ₃ fine particle photocatalysts having different intensity ratios of the cubic (100) plane and the monoclinic (002) plane was compared, and the characteristic diagram shown in FIG. 8 was obtained. It was. From FIG. 8, it is clear that when the intensity ratio of the cubic (100) plane is increased, the acetaldehyde gas decomposition activity after 1 hour is improved.

In the fourth embodiment, the visible light responsive photocatalyst is a WO ₃ fine particle having an average particle diameter of 0.01 to 0.1 μm and includes cubic and monoclinic WO ₃ fine particles, and By setting the strength ratio of the cubic (100) plane to be stronger than that of the monoclinic (002) plane, high acetaldehyde gas decomposition activity can be obtained.

(Fifth embodiment)
FIG. 9 shows a production apparatus for producing photocatalyst fine particles. This manufacturing apparatus includes a spray dryer main body A, a gas / liquid mixing unit B, a pressurized air introducing unit C, a solution introducing unit D, and a granular material collecting unit E. Reference numeral 21 in the drawing indicates a drying chamber provided with a distributor 22 at the top. Here, the distributor 22 functions as an air inlet for heating the drying chamber 21 to 200 ° C. In the drying chamber 21, a spray nozzle 23 and a pipe 25 a interposed with a solenoid valve 24 are arranged so as to penetrate the distributor 22. The pipe 25a functions as an air inlet that pressurizes and atomizes the aqueous solution. The upper part of the drying chamber 21 is supplied with air by a pipe 25b. The pipe 25b functions as a hot air supply port for heating the aqueous solution and air. The pipe 25a is branched into a pipe 25c with a needle valve 26 interposed on the way.

  The pipe 25 c is connected to the upper part of the spray nozzle 23. A tube 29 for supplying the sample 27 into the spray nozzle 23 by a pump 28 is connected to the upper part of the spray nozzle 23. The amount of the sample 27 supplied into the spray nozzle 23 can be appropriately adjusted by a pump 28. A cyclone 30 for taking out the sprayed product from the spray nozzle 23 is connected to the side of the drying chamber 21. Further, a product container 31 that collects photocatalyst fine particles and an aspirator 32 for exhaust are connected to the cyclone 30.

  Temperature sensors (not shown) are arranged on the inlet side and the outlet side of the drying chamber 21 so that the temperature of the air supplied to the drying chamber 21 and the atmospheric temperature of the photocatalyst fine particles sent to the cyclone 30 are measured. . Further, the air supplied into the pipe 25 c is mixed with the sample 27 supplied into the tube 29 on the upper side of the spray nozzle 23, and ejected in a mist form from the lower part of the spray nozzle 23.

Next, the case where photocatalyst fine particles are produced using the production apparatus of FIG. 9 will be described.
First, for example, a 4 mass% ammonium paratungstate aqueous solution (sample) is sent into the spray nozzle 23 of FIG. 9 together with pressurized air, and sprayed from the tip of the spray nozzle 23 in a 200 ° C. hot air atmosphere to obtain a particle size of 1 to Spray to 10 μm to produce a granular material. At this time, pressurized air is sent from the pipe 25 a to the vicinity of the tip of the spray nozzle 23, and oxygen is supplied to the photocatalyst fine particles sprayed from the spray nozzle 23. If the concentration of the aqueous solution is 4% by mass, a granular raw material of 40 to 400 nm of ammonium paratungstate can be obtained. Next, the raw material is forcibly dried and recrystallized by performing a heat treatment for a short period of time in the drying chamber 21 at 800 ° C. for 1 to 10 minutes. Thus, tungsten trioxide photocatalyst particles having tungsten trioxide fine particles as the main component, the average particle diameter of the fine particles being 0.5 μm or less, preferably 0.1 μm or less, and the crystal structure of which is monoclinic are formed. Subsequently, the photocatalyst fine particles in the drying chamber 21 are collected in the product container 31 from the cyclone 30 while the aspirator 32 evacuates the drying chamber 21.

According to the fifth embodiment, it is possible to obtain WO ₃ crystal photocatalyst particles with few oxygen defects by sending pressurized air from the pipe 25a to the vicinity of the tip of the spray nozzle 23 and supplying oxygen to the photocatalyst particles. . Further, by performing a heat treatment for a short period of time in the drying chamber 21 at 800 ° C. for 1 to 10 minutes, the XRD analysis is performed on the (001) plane and the (200) plane as in the fourth embodiment. Monoclinic and cubic composite WO ₃ photocatalyst fine particles having a strong peak can be obtained.

(Sixth embodiment)
The fine particles of the present embodiment are tungsten trioxide fine particles produced by dissolving a commercially available ammonium paratungstate in an aqueous solvent and then heating and firing the raw material obtained by recrystallization at high temperature in the atmosphere for 1 minute. is there.
Also for the WO ₃ photocatalyst fine particles of this embodiment, by adjusting the heating and firing conditions, monoclinic crystals having strong peaks on the (001) plane and the (200) plane by XRD analysis as in the fourth embodiment It can be synthesized into WO ₃ photocatalyst fine particles of cubic composite form.

(Seventh embodiment)
FIG. 10 is a cross-sectional view schematically showing the configuration of a fluorescent lamp as a photocatalyst according to the present invention. FIG. 10 (A) is a cross-sectional view including a cut-out cross section, and FIG. 10 (B) is a configuration of the fluorescent lamp. The typical sectional view of the photocatalyst film which is is shown.
Reference numeral 40 in the figure denotes a fluorescent lamp as a photocatalyst body, which is composed of a fluorescent lamp body 50 and a photocatalyst film 60 formed on the surface of the fluorescent lamp body 50. The fluorescent lamp body 50 includes a translucent discharge vessel 51, a phosphor layer 52, a pair of electrodes 53, 53, a discharge medium (not shown), and a base 54.

  The translucent discharge vessel 51 includes an elongated glass bulb 51a and a pair of flare stems 51b. The glass bulb 51a is made of soda lime glass. The flare stem 51b includes an exhaust pipe, a flare, an internal introduction line, and an external introduction line. The exhaust pipe is used to communicate the inside and outside of the translucent discharge vessel 51 to exhaust the inside of the translucent discharge vessel 51 and enclose a discharge medium. The exhaust pipe is sealed after the discharge medium is sealed. The flare is sealed at both ends of the glass bulb 51a to form a translucent discharge vessel 51.

  The phosphor layer 52 is made of a three-wavelength light emitting phosphor and is formed on the inner surface of the translucent discharge vessel 51. The pair of electrodes 53, 53 are connected between the distal end portions of the pair of internal lead-in wires facing each other inside the both ends of the translucent discharge vessel 51. The electrode 53 is made of a tungsten coil filament and an electron-emitting material deposited on the coil filament.

  The discharge medium is made of mercury and argon, and is enclosed in the translucent discharge vessel 51. An appropriate amount of mercury is sealed through an exhaust pipe. The base 54 includes a base body 54a and a pair of base pins 54b and 54b. The base body 54 a has a cap shape and is bonded to both ends of the translucent discharge vessel 51. The pair of base pins 54b, 54b are supported by the base body 54a in an insulative relationship with each other and are connected to external lead-in wires, respectively.

  The photocatalyst film 60 is a film made of a photocatalyst paint mainly composed of tungsten trioxide fine particles (average particle diameter: 0.1 μm), and has a film thickness of about 0.5 to 3 μm. The tungsten trioxide fine particles maintain the crystal structure of the above embodiment even after the coating is completed. The photocatalyst film 60 is formed of photocatalyst fine particles 61 and a binder 52 having a good ultraviolet or visible light transmission property such as alumina fine particles, silica fine particles, or zirconia fine particles. The photocatalyst fine particles 51 are composed of tungsten trioxide fine particles 51a and calcium carbonate fine particles 51b attached to the surfaces of the tungsten trioxide fine particles 51a. The binder 52 is added in a range of 10 to 50% by mass with respect to the tungsten trioxide fine particles 51a. Moreover, when acrylic modified silicone or silicone resin is used for the binder 52, it can be set as the photocatalyst film | membrane hardened | cured at 20-200 degreeC. The calcium carbonate fine particles 51b function as a substance that adsorbs NOx (nitrogen oxide) or SOx (sulfur oxide). If it is not necessary to suppress the deterioration of the tungsten trioxide fine particles 51a by NOx or SOx, the calcium carbonate is obtained. The attachment of the fine particles 51b is not essential.

FIG. 11 is an explanatory view schematically showing a configuration of a deodorizing unit as a photocatalyst body according to the invention, FIG. 11 (A) is a schematic perspective view of the deodorizing unit, and FIG. 11 (B) is FIG. ) Is a schematic side view. In FIG. 11B, the tungsten trioxide fine particles are not shown for convenience.
Reference numeral 61 in the figure denotes a deodorizing unit as a photocatalyst, which has a corrugated plate-like cross section arranged between upper and lower flat mesh-like first and second filters 62a and 62b and these filters 62a and 62b. And a third filter 63. Each filter 62a, 62b, 63 carries tungsten trioxide fine particles (average particle size: 0.1 μm) 64 according to the present invention. A plurality of GaN blue light emitting diodes 65 are disposed below the second filter 62b. Instead of the diode 65, a white light emitting diode using a phosphor excited by blue light may be arranged. In the deodorizing unit having such a configuration, when the air passes through the third filter 63 between the first and second filters 62a and 62, for example, from the left side to the right side, the air touches the trioxide fine particles carried on each filter. The deodorization is performed.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the components without departing from the gist of the invention in the stage of implementation. Furthermore, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine the component covering different embodiment suitably.

FIG. 1 shows a schematic view of an apparatus for synthesizing tungsten oxide according to the present invention. FIG. 2 shows a schematic diagram of a measuring apparatus for the acetaldehyde gas decomposition test. FIG. 3 shows the acetaldehyde gas decomposition effect of the tungsten oxide film according to the embodiment of the present invention. FIG. 4 shows an XRD chart when XRD analysis is performed on the tungsten oxide fine particle photocatalyst according to the embodiment of the present invention. FIG. 5 shows an XRD chart when the XRD analysis is performed on the tungsten oxide fine particle photocatalyst according to the present invention by variously changing the heating temperature by the burner. FIG. 6 is a characteristic diagram of the dispersion state when the frequency of the WO ₃ fine particles according to the _third embodiment is different from 100 kHz and 60 kHz. FIG. 7 shows a characteristic diagram of XRD data of a WO ₃ fine particle photocatalyst having different crystal planes. FIG. 8 is a characteristic diagram showing the relationship between the cubic (100) plane: monoclinic (002) plane intensity ratio of the WO ₃ fine particles according to the fourth embodiment and the acetaldehyde gas decomposition rate after 1 hour. FIG. 9 shows a schematic view of a production apparatus for forming photocatalyst fine particles according to the present invention. FIG. 10 is a schematic explanatory view of a fluorescent lamp as a photocatalyst according to the present invention. FIG. 11 is a schematic explanatory view of a deodorizing unit as a photocatalyst according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Measurement container, 2 ... Photocatalyst watch glass, 4 ... Light source, 5 ... Multi gas monitor, 40 ... Fluorescent lamp, 41 ... Translucent discharge container, 42 ... Phosphor layer, 43 ... Electrode, 50 ... Fluorescent lamp main body, 51 ... Photocatalyst fine particles, 51a ... Tungsten trioxide, 51b ... Carbonic acid or calcium fine particles, 52 ... Binder, 60 ... Photocatalyst film, 61 ... Deodorizing unit, 62a, 62b, 63 ... Filter, 64 ... Tungsten trioxide fine particles.

Claims (12)

A visible light responsive photocatalytic synthesis method characterized in that tungsten oxide fine particles having a crystal structure in which the peak intensity of the (200) plane is the strongest by XRD analysis are synthesized by sublimation or combustion of metallic tungsten. 2. The visible light responsive photocatalytic synthesis method according to claim 1, wherein tungsten oxide fine particle fumes generated by sublimation or combustion of metallic tungsten are collected. 3. The visible light responsive photocatalytic synthesis method according to claim 2, wherein the tungsten oxide fine particle fumes are passed through an electric furnace of 600 to 1000 [deg.] C. in an oxidizing atmosphere. A visible light responsive photocatalytic material comprising tungsten oxide fine particles having a crystal structure in which the peak intensity of the (200) plane is the strongest as measured by XRD analysis. 5. The visible light responsive photocatalytic material according to claim 4, wherein the tungsten oxide fine particles contain a larger number of cubic crystal structure particles than other crystal structure particles. 6. The visible light responsive photocatalytic material according to claim 4, wherein the tungsten oxide fine particles have an average particle diameter of 0.01 to 0.1 [mu] m. 7. The visible light responsive photocatalytic material according to claim 6, comprising at least particles having a cubic crystal structure. 8. The visible light responsive photocatalytic material according to claim 7, further comprising at least one of monoclinic and triclinic crystal structure particles in addition to the cubic crystal structure particles. . A visible light responsive photocatalyst coating material, wherein the visible light responsive photocatalyst material according to any one of claims 4 to 8 is dispersed in pure water. 10. The visible light responsive photocatalyst coating material according to claim 9, wherein the photocatalyst material is dispersed by an ultrasonic wave of 40 to 120 kHz. 9. The visible light responsive photocatalyst medium comprising the visible light responsive photocatalyst material according to claim 4 and a metal oxide binder of Al, Zr, or Si or a composite oxide binder of Al—Si. 1 to 10% by mass of the visible light responsive photocatalytic coating material. A visible light responsive photocatalyst body, wherein the visible light responsive photocatalyst paint according to claim 9 is applied to form a photocatalyst film.

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