JP7096743B2 - Photocatalyst composite material, manufacturing method of photocatalyst composite material and photocatalyst device - Google Patents

Description

Embodiments of the present invention relate to a photocatalyst composite material, a method for producing a photocatalyst composite material, and a photocatalyst apparatus.

Photocatalysts are known to generate light-excited holes and promote strong oxidation reactions. Various photocatalysts having such an action are known, and this promoting action is used for decomposition and removal of harmful organic molecules, sterilization, maintenance of hydrophilicity of a base material, and the like.

When a photocatalyst is to be applied to such an application, it may come into contact with a substance to be treated, for example, as a photocatalyst composite material in which a photocatalyst is supported on a substrate. In order to carry out the treatment efficiently by such a method, it is common to increase the amount of the photocatalyst supported on the substrate. However, increasing the amount of the photocatalyst directly leads to an increase in cost, and there is also a problem that the photocatalyst is easily peeled off from the substrate. Further, although a shape such as a fractal structure can be adopted in order to increase the surface area, the manufacturing method tends to be complicated and there is room for consideration.

Japanese Patent No. 4163374 Japanese Unexamined Patent Publication No. 2000-135755

In view of the above problems, the embodiment is intended to provide a photocatalyst composite material having high activity and being hard to peel off, a manufacturing method capable of easily producing the photocatalyst composite material, and a photocatalyst apparatus provided with the photocatalyst composite material. Is.

The photocatalyst composite material according to the embodiment includes a base material and a photocatalyst layer containing photocatalyst particles, and when the substrate side surface of the _{photocatalyst} layer is S _b and the opposite side surface is St, the photocatalyst particles in the vicinity of S _b . The average particle diameter r _b is smaller than the average particle diameter r _t of the photocatalytic particles in the vicinity of the _St.

Further, the method for producing a photocatalyst composite material according to an embodiment includes a step of applying a dispersion liquid containing the first photocatalyst particles on a substrate, and second photocatalyst particles having an average particle size larger than that of the first photocatalyst particles. It includes a step of applying a dispersion liquid.

Further, the photocatalyst device according to the embodiment is
With the photocatalyst composite material
A light irradiation member that causes photocatalytic activity on the substrate,
It is provided with a supply member for supplying the substance to be treated to the photocatalyst composite material.
The photocatalytic composite material whose catalytic activity is generated by the light promotes a chemical reaction for treating the substance.

It is a schematic diagram of the photocatalyst composite material which concerns on embodiment. It is a schematic diagram of the manufacturing method of the photocatalyst composite material which concerns on embodiment. It is a schematic diagram of the photocatalyst apparatus which concerns on embodiment.

Hereinafter, embodiments will be described with reference to the drawings.

It should be noted that the same reference numerals are given to common configurations throughout the embodiments, and duplicate description will be omitted. In addition, each figure is a schematic diagram for promoting the embodiment and its understanding, and there are some differences in shape, dimensions, ratio, etc. from the actual device, but these are based on the following explanation and known techniques. The design can be changed as appropriate.

(Embodiment 1)
As shown in FIG. 1, the photocatalyst composite material 10 according to an example of the embodiment includes a base material 11 and a photocatalyst layer 12. The _{photocatalyst} layer 12 has an interface S _b on the substrate side and an interface St on the opposite side. In the photocatalyst layer exemplified in FIG. 1, particles having a small particle size are localized on the S _b side, and particles having a large particle size are localized on the _St side. Therefore, when the average particle diameter r _{b of the photocatalyst particles in the vicinity of S b and} the average particle diameter r _t of the photocatalyst particles in the vicinity of _St are compared, r _b is smaller.

Here, the vicinity of S _b or the vicinity of _St can generally be a region in which the photocatalyst layer is divided into a region close to S _b and a region close to _St.

In FIG. 1, as a schematic diagram, a structure in which two types of “small particles” are arranged on the S _b side and “large particles” are arranged on the _St side is shown. When the particle size distribution of such photocatalytic particles is measured, the distribution curve has two peaks. However, the structure is not limited to this, and two or more types of particles having different sizes are laminated in a layered manner, or the particle size continuously changes from S _b to _St. May be good. In the former case, the particle size distribution curve has two or more peaks, but in the latter case, a clear peak may not appear in the particle size distribution.

Excellent effects can be obtained by arranging the photocatalytic particles in this way. First, if the photocatalytic particles are small, they tend to be easily peeled off by the action of water flow or air flow in water or air. However, since the particles located in the vicinity of _Sb and in contact with the surface of the base material are strongly adsorbed by the base material, they are difficult to peel off even if the average particle size is small. Further, if the photocatalyst particles in the vicinity of Sb are small, the surface area of the photocatalyst existing near the surface of the substrate increases, so that high catalytic activity can be easily obtained.

On the other hand, the photocatalytic particles existing in the vicinity of St are more difficult to peel off as the average particle size is larger. In addition, the larger the particle size, the wider the space between the particles, so that the substances and decomposition products treated by the photocatalyst tend to diffuse.

Here, the particle size and the average particle size of the photocatalyst particles can be measured by observing the surface and cross section of the photocatalyst layer photographed by TEM (Transmission Electron Microscope). Specifically, the cross section of the photocatalyst layer is observed by TEM at a magnification of 1 million, and the diameter when the projected area of the particles is converted into a circle having the same area by image processing is defined as the particle diameter. Further, the average particle size _{r b} of the photocatalyst particles in the vicinity of _Sb or the average particle size _rt of the photocatalyst particles in the vicinity of St is, for example, at least 100 particles of the photocatalyst particles arranged in the vicinity of Sb or St. Obtained from the average diameter.

In the embodiment, r _b is preferably 2 to 50 nm. When r _b is 2 nm or more, the stability of the dispersion liquid of the photocatalytic particles in the manufacturing process is high, and the possibility of dissolution or aggregation is low. On the other hand, when r _b is 50 nm or less, the photocatalytic particles can be sufficiently adhered to the surface of the substrate, the total surface area of the photocatalyst particles is further increased, and high catalytic activity can be obtained. Further, it is preferable that the _rt is 40 to 500 nm. When _rt is 40 nm or more, the space between the particles becomes wide, so that the substance to be treated is sufficiently diffused in the photocatalyst layer to obtain high catalytic activity, and the photocatalyst layer is peeled off by air flow or water flow. Is difficult to place. On the other hand, when _rt is 500 nm or less, the dispersibility of the dispersion liquid in the manufacturing process tends to be high, and the catalytic activity tends to be high.

The average particle size of all the photocatalyst particles contained in the photocatalyst layer shall be 2 to 500 nm from the viewpoint of the stability of the dispersion, the processability when applied to the substrate, and the viewpoint of exerting the photocatalyst function. It is preferably 10 to 400 nm, more preferably 20 to 200 nm, and particularly preferably 20 to 200 nm.

As the photocatalyst particles, those containing metal oxides such as tungsten oxide, titanium oxide, zinc oxide, niobium oxide and tin oxide are used. Two or more kinds of these photocatalytic particles can be used in combination. Among these, a photocatalyst containing tungsten oxide is preferable because it has visible light responsiveness. In particular, it is preferable that the tungsten oxide crystal contains a monoclinic or triclinic crystal structure because the activity of the catalyst tends to be high.

In addition, photocatalytic particles having different chemical compositions can be used in combination. This not only makes it possible to combine photocatalysts having different functions, but also improves the robustness of the photocatalyst layer and makes it possible to more effectively utilize the light energy applied to the catalyst. For example, when a material that is easily charged positively is used as the base material, if tungsten oxide that is easily negatively charged is placed in the vicinity of _Sb and titanium oxide is placed in the vicinity of _St , the adhesion of the photocatalyst layer to the base material is improved. And the robustness is improved. In this case, the average particle size of tungsten oxide is smaller than the average particle size of titanium oxide. Further, by combining photocatalysts having a large difference in light absorption spectra, each photocatalyst particle can efficiently absorb light and exhibit catalytic activity. For example, by arranging tungsten oxide having an absorption end of light absorption of about 470 nm in the vicinity of St and titanium oxide having an absorption end of light absorption of about 400 nm in the vicinity of Sb, the position is far from the light absorption surface. Tungsten oxide can absorb light efficiently.

The photocatalyst layer preferably contains 20 to 100% by mass of photocatalyst particles in order to obtain high catalytic activity based on the total mass of the photocatalyst layer. The photocatalyst layer may be composed of only photocatalyst particles, but may include an auxiliary catalyst, silver nanowires, a binder and the like, which will be described later.

The photocatalyst layer of the present embodiment may further contain a co-catalyst. This co-catalyst is often contained in the form of nanoparticles. As the material of the co-catalyst, a metal element compound is preferable. For example, the co-catalyst for the tungsten oxide photocatalyst can contain at least one metal element selected from Ti, Sn, Zr, Mn, Fe, Ni, Pd, Pt, Cu, Ag, Zn, Al, Ru and Ce. Of these, metal oxides of Cu, Fe, and Ni or composite oxides thereof are preferable. The content of the metal element such as the transition metal element with respect to the total amount of the photocatalyst particles and the co-catalyst particles can be in the range of 0.01 to 50% by mass. When the content of the transition metal element exceeds 50% by mass, the light transmittance tends to decrease and the activity of the catalyst tends to decrease. The content of the transition metal element is more preferably 10% by mass or less, still more preferably 2% by mass or less. The lower limit of the content of the transition metal element is not particularly limited, but the content is preferably 0.01% by mass or more in order to more effectively exhibit the effect of adding the co-catalyst. The oxides of the above transition metals tend to be positively charged. Precious metal co-catalyst particles such as Pt and Pd are also preferable, and these are preferable because they can be protected by an organic polymer and easily charged positively.

In embodiments, the zeta potential can be measured by electrophoretic light scattering. Specifically, it can be measured by combining a capillary cell with Zetasizer Nano ZS (trade name) manufactured by Malvern. The pH of the dispersion is adjusted by adding dilute hydrochloric acid and dilute potassium hydroxide aqueous solution to pure water in which photocatalyst-containing substances and co-catalyst particles are dispersed.

Here, the cocatalyst means a catalyst that further enhances the photocatalytic action of the photocatalytic particles. More specifically, for example, it is preferable to use copper oxide, which is a p-type semiconductor, as an auxiliary catalyst for tungsten oxide, which is an n-type semiconductor. Since the energy level of the conduction band of tungsten oxide is slightly higher than that of the valence band of the cocatalyst, the electrons excited by the valence band when the tungsten oxide is irradiated with light move to the valence band of the cocatalyst. Furthermore, the so-called Z scheme, which is excited by light and excited by the transmission zone of the co-catalyst, raises the energy level of electrons even by visible light and reduces oxygen in the air to generate oxygen radicals and hydrogen peroxide. can do. Holes are generated in the valence band of tungsten oxide to decompose organic molecules and the like. Oxygen radicals and hydrogen peroxide also decompose organic molecules.

Further, the metal oxide co-catalyst has a positive zeta potential. On the other hand, photocatalytic particles such as tungsten oxide have a negative zeta potential. Therefore, the photocatalyst particles and the co-catalyst particles are easily adsorbed, and the catalytic activity is likely to be further enhanced.

The photocatalyst layer of the present embodiment may further contain silver nanowires. Tungsten oxide is difficult to form a uniform composite with spherical silver particles that are easily negatively charged, but it is easy to form a uniform composite structure because the photocatalytic particles are easily held between the network structures composed of silver nanowires. ..

In general, silver nanowires tend to agglomerate easily, but the photocatalytic dispersion according to the embodiment has less agglomeration. It is considered that this is because the coexisting photocatalytic particles also have a function of a dispersant and make it difficult for aggregation to occur.

In addition, the photocatalyst layer also tends to be mechanically stable due to the network structure formed by the silver nanowires, and the outflow of the silver nanowires is unlikely to occur. Furthermore, antibacterial properties are generated by a very small amount of silver ions and are maintained for a long time. Further, the silver nanowire has a photoelectric field enhancing action by plasmon resonance, and has an action of enhancing the activity of the photocatalytic particles around the silver nanowire.

The shape of the silver nanowires is not particularly limited, and is selected so as to optimize the expected plasmon effect and the dispersed state in the dispersion liquid. For example, in embodiments, the silver nanowires preferably have an average diameter of 10 to 200 nm, an average length of 1 to 50 μm, and an average aspect ratio of 100 to 1000. More preferably, the average diameter is 20 to 100 nm, the average length is 4 to 30 μm, and the average aspect ratio is 200 to 500. Here, the average diameter and average length of the silver nanowires can be measured by observing the surface and cross section of the photocatalyst layer photographed at 200,000 times by SEM (Scanning Electron Microscope). The diameter of the silver nanowire corresponds to the length of the width of the silver nanowire planar image. The length of the silver nanowire corresponds to the length in the longitudinal direction of the silver nanowire planar image. Here, when the silver nanowire is curved, the length when the shape is formed into a straight line is adopted. When the width of one silver nanowire changes in the longitudinal direction, the width is measured at three different points, and the average thereof is taken as the width of the nanowire. The average value of these values is obtained from the measured values of 50 randomly selected nanowires.

When the silver nanowires are combined, the blending ratio of the photocatalyst particles and the silver nanowires is preferably 1/10000 to 1/10 times the mass of the silver nanowires based on the mass of the photocatalyst particles, and 1/1000 to 1 It is more preferable that it is / 10 times. When the compounding ratio of the silver nanowires is large, the photoexcitation of the photocatalyst tends to be hindered by the light absorption of the silver nanowires, and when the compounding ratio of the silver nanowires is small, the effect of improving the catalytic activity by the silver nanowires tends to be small.

The photocatalyst layer of the present embodiment may further contain alumina hydrate. Alumina hydrate is a hydrate represented by Al ₂ O ₃ · (H ₂ O) _x (0 <x ≦ 3). Alumina hydrate particles (hereinafter, simply referred to as alumina particles) are excellent as binders and prevent aggregation of catalyst particles, thereby stabilizing a photocatalytic dispersion. When applied on a substrate, it tends to form a uniform and robust film.

Alumina particles have various forms, but boehmite (x = 1) or pseudo-boehmite (1 <x <2) is preferable. Boehmite and pseudo-boehmite are stable in a polar solvent such as water, and a robust coating film can be easily formed by coating and drying. In particular, alumina particles having a fibrous or plate-like shape have a great effect of preventing agglomeration of catalyst particles.

When the alumina particles are used, the blending ratio of the photocatalyst particles and the alumina particles is preferably 0.005 to 0.1 times, preferably 0.01 to 0, based on the mass of the photocatalyst particles. It is preferably 0.03 times. If the amount of alumina hydrate is too large, the photocatalytic activity of the photocatalytic layer may decrease, and if it is too small, the stability of the photocatalytic layer may decrease.

The shape of the alumina particles is not particularly limited, but may be fibrous, for example. When the alumina particles have a fibrous shape, the diameter is preferably 1 to 10 nm and the length is preferably 500 to 10000 nm. More preferably, the diameter is 2 to 8 nm and the length is 800 to 60,000 nm, and more preferably the diameter is 3 to 6 nm and the length is 1000 to 3000 nm.

The photocatalyst layer may further contain other oxides. For example, silicon oxide has the function of increasing the hydrophilicity of the photocatalytic layer. In addition, tin oxide increases the conductivity of the photocatalyst layer to prevent charging and make it difficult for stains to adhere.

The photocatalytic layer may contain graphene oxide or graphite oxide. This prevents the catalyst particles from aggregating with each other and maintains stability and photocatalytic activity for a long period of time. The blending ratio of the photocatalyst particles with graphene oxide or graphite oxide contained in the photocatalyst layer is that the mass of graphene oxide or graphite oxide based on the mass of the photocatalyst particles is 1 / 200,000 to 1/100 times. It is preferably 1 / 100,000 to 1/1000 times, more preferably 1 / 50,000 to 1 / 10,000 times, and particularly preferably 1 / 50,000 to 1 / 10,000 times. When this compounding ratio is small, the effect of improving stability tends to be small, and when it is large, the effect of improving photocatalytic activity tends to be small.

In the embodiment, the base layer can be installed between the base material and the photocatalyst layer. As the base layer, a layer containing an inorganic oxide is preferable because it can prevent deterioration of the base material due to the photocatalyst and prevent peeling from the photocatalyst layer. Examples of the inorganic oxide include silica, alumina, and zirconia. It is more preferable that the inorganic oxide is an aluminum oxide. Many base materials have a negative zeta potential, and aluminum oxide, which tends to have a positive zeta potential, tends to stably coat the base material. In addition, it is easy to stably carry photocatalytic particles and silver nanowires having a negative zeta potential.

In the embodiment, the coverage of the base layer with respect to the surface area of the base material is preferably 80% or more. Here, the coverage is the ratio of the area covered by the base layer to the surface area of the base material. When the coverage is in such a range, the effect of adhering the catalyst of the base layer and protecting the base material can be obtained. The coverage can be observed at 25 times by SEM, the area of the surface of the base material and the area of the portion covered with the base layer are measured, and can be obtained from the ratio.

The zeta potential of the base material and the base layer can be measured as tracer particles using a flat plate zeta potential measuring cell using a zeta potential nano-ZS manufactured by Malvern Co., Ltd. by an electrophoretic light scattering method. The pH is adjusted by adding dilute hydrochloric acid and dilute potassium hydroxide aqueous solution to pure water.

The substrate can be selected from any material, such as organic and metallic materials, including, for example, metals, ceramics, paper, and polymer films. The base material may be a material having a smooth surface or a porous body. A porous body is preferable because it can increase the surface area and easily increase the amount of the photocatalyst carried. Further, it is preferable that the material of the base material contains an organic substance because coloring and surface modification are facilitated.

Since the polymer film can be a flexible transparent film, the range of applications of the photocatalytic composite material can be expanded. As the polymer material, those having high visible light transparency such as polyethylene terephthalate, polycarbonate, polyethylene naphthalate, and acrylic resin can be preferably used. It is also preferable that it is a curable resin that forms a strong surface. In particular, polyethylene terephthalate is highly flexible, and when graphene oxide is used, it is preferable because it has good adhesion to it. It is also preferable that it is a curable resin that forms a strong surface.

The substrate preferably has a negative zeta potential in water at 20 ° C. and pH 6. By using such a base material, the association of the catalyst particles is suppressed, and a uniform film can be easily obtained.

The surface of the base material may be smooth, but may be uneven. When the surface roughness of the base material is increased, the surface area of the base material surface is increased, and more photocatalytic particles of the photocatalyst layer on the base material can be supported.

For example, the absolute value of the arithmetic mean roughness Ra of the surface of the base material is preferably 0.2 μm to 20 μm. The arithmetic mean roughness Ra can be measured according to the JIS standard. When the arithmetic mean roughness Ra is smaller than 0.2 μm, the contact area between the photocatalyst and the base material becomes small and tends to be easily peeled off. When the arithmetic mean roughness Ra is larger than 20 μm, the photocatalyst particles are accumulated only in the recesses of the base material, and the film thickness of the photocatalyst layer becomes too large, so that activation of the lower photocatalyst by light tends to be difficult to occur.

The "photocatalytic action" in the embodiment means decomposition of harmful substances such as ammonia and aldehydes, elimination of unpleasant odors of tobacco and pet odors, antibacterial action and antiviral action against Staphylococcus aureus, Escherichia coli and the like. Also, it has an antifouling effect that makes it difficult for dirt to adhere.

(Second Embodiment)
The photocatalytic composite material according to the embodiment can be produced by any method, and can be produced, for example, by the method as described below.

2 (A) to 2 (C) show schematic views showing an example of a method for producing a photocatalyst composite material according to a second embodiment.

First, the dispersion liquid 21 containing the first photocatalyst particles is applied to the surface of the base material 11 to form the first photocatalyst particle layer 21a (FIG. 2A). The first photocatalyst particles can be selected from the above-mentioned photocatalyst particles. The average particle size of the first photocatalyst particles is preferably 2 to 50 nm. This dispersion may contain co-catalyst particles, silver nanoparticles and the like, if necessary. Water is generally used as the dispersion medium. However, alcohol can be mixed if necessary. When the dispersion medium contains alcohol, the surface tension of the dispersion liquid decreases and it becomes easy to apply it to the substrate. As the alcohol, ethanol, methanol, isopropanol and the like are preferable, and ethanol is more preferable from the viewpoint of safety. The alcohol content is preferably 1 to 95% by mass, more preferably 5 to 93% by mass, still more preferably 10 to 90% by mass, based on the total mass of the dispersion.

Further, the content of the photocatalyst particles contained in the dispersion liquid is preferably 0.1 to 20% by mass based on the total mass of the dispersion liquid from the viewpoint of ease of coating and the like.

As the coating method, any method such as spray coating, die coating, bar coating, spin coating, screen printing and the like can be used. The batch method may be used, or the roll-to-roll method may be used to continuously apply to a large area.

After coating, if necessary, a part or all of the dispersion medium contained in the layer 21a is dried and removed. As a drying method, there are methods such as warm air heating, infrared heating, hot plate heating, and microwave heating. Of these, infrared heating and warm air heating are preferable because they are simple and can be used for the roll-to-roll method.

Then, a dispersion liquid containing the second photocatalyst particles 22 is applied to form the second photocatalyst particle layer 22a (FIG. 2B). As the dispersion liquid to be used, a second photocatalyst having a larger average particle diameter than the first photocatalyst particles is used as the photocatalyst particles, and the dispersion liquid is arbitrarily selected from the materials and adjustment conditions described for the dispersion liquid of the first photocatalyst. be able to. The average particle size of the second photocatalyst particles is preferably 40 to 500 nm. Further, the coating method and the drying conditions can be arbitrarily selected from the above. Here, when the first photocatalyst particle layer is not completely dried and the second photocatalyst particle layer is formed, some mixing may occur at the interface between them, but at the interface _Sb and the interface _St. Has little effect, and the subject 1 photocatalyst particles are _localized in the vicinity of _Sb , and the second photocatalyst particles are localized in the vicinity of St.

Further, if necessary, the dispersion medium is dried and removed to obtain the photocatalyst composite material 10 according to the embodiment (FIG. 2 (C)).

By such a method, the photocatalyst composite material according to the embodiment can be obtained. It is also possible to apply a dispersion liquid containing the second photocatalyst particles, dry and remove a part or all of the dispersion medium, and then stack photocatalyst particles having a larger average particle diameter.

In general, when a mixed dispersion of large particles and small particles is applied, it is affected by gravity, and small particles are affected by the liquid flow generated in the dispersion during drying. That is, it is easy to _gather in the vicinity of St. Therefore, the structure is different from that of the photocatalytic particles according to the embodiment. Therefore, the photocatalytic particles according to the embodiment can be obtained by sequentially stacking the small particles first and the large particles later.

Prior to the application of the first photocatalyst, the base layer can be formed in advance. The base layer can also be formed by dispersing an inorganic oxide or the like as a material of the base layer in a dispersion medium, and then applying and drying by the same method as described above.

The total weight of the first photocatalyst particles deposited on the substrate is preferably less than the total weight of the second photocatalyst particles deposited on the substrate. Since the surface area of the particles is inversely proportional to the particle diameter, sufficient catalytic activity can be obtained even if the amount of the first photocatalytic particles deposited is small. On the other hand, if the amount of the first photocatalyst particles deposited is too large, the photocatalyst layer tends to peel off, the space between the particles becomes small, and the diffusion of the substance to be treated tends to be hindered.

Further, it is preferable to select an appropriate zeta potential for the first photocatalyst particles, the second photocatalyst particles, and the base layer material to be used. By selecting the first photocatalyst particles and the second photocatalyst particles having different zeta potential codes, and by selecting the underlayer material and the first photocatalyst particles having different zeta potential codes. The stability of the photocatalyst layer can be improved.

(Third embodiment)
FIG. 3 shows a schematic view showing an example of the configuration of the photocatalyst device according to the third embodiment.

As shown in the figure, the photocatalyst device 30 according to the first embodiment includes a photocatalyst composite material 31 according to the first embodiment, a light irradiation member 32 that causes photocatalytic activity on a substrate, and a supply member that supplies a substance to the photocatalyst composite material. 33 is provided. A chamber 34 containing these members may be further provided. Further, it is also possible to provide an introduction unit 35a for introducing the substance to be treated and a discharge port 35b for discharging the treated substance.

Here, the substance to be treated is a substance to be changed by a chemical reaction promoted by the photocatalytic action of the photocatalytic composite material. Specific examples thereof include a gas containing a toxic component for which harmful components are desired to be removed, a gas containing an odor for which deodorization is desired, and a waste liquid containing a pollutant.

The light irradiation member may be an optical system member that guides light to a photocatalytic composite material by using external light or indoor light, or may be a light source such as a lamp or an LED. When using external light or indoor light, the photocatalyst composite material may be a member installed or moved at a position where it is easily received. When using a light source, LEDs are preferable from the viewpoint of low power consumption and miniaturization.

As a member for supplying a substance to the photocatalyst composite material, if it is a gas, for example, a fan or a pump can be mentioned. Further, when a gas or liquid is introduced into a chamber containing a photocatalyst composite material, the chamber or a nozzle for introducing the gas or liquid into the chamber is also a supply member. Further, the gas or liquid may be naturally diffused in the chamber, but convection generated by a heater or the like can also be used. In this case, the heater is also a supply member. Further, when natural diffusion is used, the photocatalytic composite material may be a member installed or moved at a position where it easily comes into contact with a substance.

When the photocatalytic composite is in the form of a flat plate, the substance to be treated can flow along its surface. Further, when the photocatalyst composite material is a porous body and the substance can pass through the porous body, the contact area between the substance and the catalyst increases, and the treatment efficiency becomes high, which is preferable. Further, even when the substance to be treated flows along the surface of the photocatalyst composite material, if it is porous, the contact area becomes large. Therefore, the photocatalyst composite material is preferably porous, more preferably cloth-like.

In this embodiment, the photocatalyst layer can further contain an adsorbent for adsorbing the substance. When such an adsorbent is contained in the photocatalyst, the efficiency of catalytic action can be improved by increasing the concentration of the substance in the vicinity of the catalyst. Examples of such an adsorbent include activated carbon, alumina, zeolite, silica gel and the like.

(Example 1)
The surface of a 1 mm thick glass plate (10 cm × 10 cm) is rubbed with # 40 sandpaper, washed with isopropanol, and then washed with pure water. The arithmetic mean roughness of the surface is 4 μm. 1 g of a fibrous alumina hydrate dispersion having an average diameter of 4 nm and an average length of 1 μm was dropped onto this, spread over the entire surface, and then dried at room temperature for 1 hour to form an underlayer. ..

Next, 1 g of a 10% aqueous dispersion of tungsten oxide fine particles having an average particle diameter of 20 nm is added dropwise, spread over the entire surface, and then dried at 60 ° C. for 1 hour. Next, 4 g of a 10% aqueous dispersion of tungsten oxide fine particles having an average particle diameter of 100 nm was added dropwise, spread over the entire surface, and then dried at 60 ° C. for 1 hour to obtain a photocatalytic composite material.

(Photocatalytic activity test)
In the acetaldehyde decomposition test, when a light-shielded sample that becomes 0 ppm after 15 minutes of irradiation with a fluorescent lamp of 6000 lux with respect to the initial concentration of 10 ppm is used, the concentration after the same time elapses is 10 ppm.

In the E. coli antibacterial test, the initial bacterial concentration was 1 × ¹⁰⁵ / ml, and the number of bacterial cells after 2 hours of light irradiation with a fluorescent lamp was 0. When a shaded sample is used, the number of bacteria after the same time has passed is 1 × 10 ³ / ml.
The photocatalytic activity hardly changes even after 300 hours of light irradiation.

(Peeling resistance test)
The photocatalyst is left in water at 30 ° C. for 1 day. No peeling is seen, and the photocatalytic activity is almost unchanged.

(Example 2)
The surface of a 150 μm-thick PET film (10 cm × 10 cm) was treated with UV ozone, and 1 g of a fibrous alumina hydrate dispersion having an average diameter of 4 nm and an average length of 1 μm was dropped over the entire surface. After spreading to, it is dried at room temperature for 1 hour to form an underlayer.

Next, 1 g of a 10% aqueous dispersion of tungsten oxide fine particles having an average particle diameter of 20 nm is added dropwise, spread over the entire surface, and then dried at 60 ° C. for 1 hour. Next, 4 g of a 10% aqueous dispersion of anatase-type titanium oxide fine particles having an average particle diameter of 100 nm was added dropwise, spread over the entire surface, and then dried at 60 ° C. for 1 hour to form a photocatalytic composite material.

(Photocatalytic activity test)
In the acetaldehyde decomposition test, the initial concentration is 10 ppm, and the concentration becomes 0 ppm after 13 spectroscopic irradiation with an LED having a center wavelength of 395 nm. When a shaded sample is used, the concentration after the same time elapses is 10 ppm.

In the Escherichia coli antibacterial test, the initial bacterial concentration was 1 × 10 ⁵ / ml, and the bacterial count after 2 hours of light irradiation with an LED was 0. When a shaded sample is used, the number of bacteria after the same time has passed is 1 × 10 ³ / ml.

The photocatalytic activity hardly changes even after 300 hours of light irradiation.

(Peeling resistance test)
The photocatalyst is left in water at 30 ° C. for 1 day. No peeling is seen, and the photocatalytic activity is almost unchanged.

(Example 3)
The photocatalyst is the same as in Example 2 except that the melamine resin film (10 cm × 10 cm) formed on the aluminum plate instead of the PET film is untreated and the photocatalyst-containing liquid is used without forming the base layer. Form a composite material.

(Photocatalytic activity test)
In the acetaldehyde decomposition test, the initial concentration is 10 ppm, but it becomes 0 ppm 20 minutes after the LED light irradiation. When a shaded sample is used, the concentration after the same time elapses is 10 ppm.

In the Escherichia coli antibacterial test, the initial bacterial concentration was 1 × 10 ⁵ / ml, and the bacterial count after 2 hours of light irradiation with an LED was 0. When a shaded sample is used, the number of bacteria after the same time has passed is 2 × 10 ³ / ml.

The photocatalytic activity hardly changes even after 300 hours of light irradiation.

(Peeling resistance test)
The photocatalyst is left in water at 30 ° C. for 1 day. No peeling is seen, and the photocatalytic activity is almost unchanged.

(Example 4)
A photocatalyst composite material is obtained in the same manner as in Example 1 except that copper oxide nanoparticles having an average particle diameter of 20 nm are added to the coating liquid in an amount of 0.05% by mass as a co-catalyst.

(Photocatalytic activity test)
In the acetaldehyde decomposition test, the initial concentration is 10 ppm, but it becomes 0 ppm 12 minutes after irradiation with fluorescent light. When a shaded sample is used, the concentration after the same time elapses is 10 ppm.

In the E. coli antibacterial test, the initial bacterial concentration was 1 × ¹⁰⁵ / ml, and the number of bacterial cells after 1.5 hours of light irradiation with a fluorescent lamp was 0. When a shaded sample is used, the number of bacteria after the same time has passed is 1 × 10 ³ / ml.

The photocatalytic activity hardly changes even after 300 hours of light irradiation.

(Peeling resistance test)
The photocatalyst is left in water at 30 ° C for one day. No peeling is seen, and the photocatalytic activity is almost unchanged.

(Example 5)
The surface of a 1 mm thick aluminum plate (10 cm × 10 cm) is rubbed with # 100 sandpaper, washed with isopropanol, and then washed with pure water. The arithmetic mean roughness of the surface is 1 μm.

Next, 1 g of a 10% aqueous dispersion of tungsten oxide fine particles having an average particle diameter of 20 nm is added dropwise, spread over the entire surface, and then dried at 60 ° C. for 1 hour. Next, 4 g of a 10% aqueous dispersion of tungsten oxide fine particles having an average particle diameter of 100 nm is added dropwise, spread over the entire surface, and then dried at 60 ° C. for 1 hour. Next, the photocatalytic composite material is obtained by heating at 600 ° C. for 3 hours in the atmosphere.

(Photocatalytic activity test)
In the acetaldehyde decomposition test, when a light-shielded sample that becomes 0 ppm 12 minutes after irradiation with a fluorescent lamp of 6000 lux with respect to the initial concentration of 10 ppm is used, the concentration after the same time elapses is 10 ppm.

In the E. coli antibacterial test, the initial bacterial concentration was 1 × ¹⁰⁵ / ml, and the number of bacterial cells after 1.5 hours of light irradiation with a fluorescent lamp was 0. When a shaded sample is used, the number of bacteria after the same time has passed is 1 × 10 ³ / ml.

The photocatalytic activity hardly changes even after 300 hours of light irradiation.

(Peeling resistance test)
The photocatalyst is left in water at 30 ° C. for 1 day. No peeling is seen, and the photocatalytic activity is almost unchanged.

(Example 6)
The photocatalyst composite material obtained in Example 2, a photocatalyst device having a 395 nm LED and a small fan is installed in a refrigerator. The power supply and control device will be installed outside the refrigerator.

(Activity test of photocatalyst device)
The photocatalyst device is driven while irradiating with light by the LED, and the initial concentration of 10 ppm of methyl mercaptan becomes 0 after 30 minutes.

The photocatalytic activity hardly changes even after 300 hours of light irradiation.

(Comparative Example 1)
The surface of a 1 mm thick glass plate (10 cm × 10 cm) is rubbed with # 40 sandpaper, washed with isopropanol, and then washed with pure water. The arithmetic mean roughness of the surface is 4 μm. 1 g of a fibrous alumina hydrate dispersion having an average diameter of 4 nm and an average length of 1 μm was dropped onto this, spread over the entire surface, and then dried at room temperature for 1 hour to form an underlayer. ..

Next, 5 g of a 10% aqueous dispersion of tungsten oxide fine particles having an average particle diameter of 20 nm is added dropwise, spread over the entire surface, and then dried at 60 ° C. for 1 hour to form a photocatalytic composite material.

(Photocatalytic activity test)
In the acetaldehyde decomposition test, the initial concentration is 10 ppm, but it becomes 0 ppm 20 minutes after irradiation with a fluorescent lamp of 6000 lux. When a shaded sample is used, the concentration after the same time elapses is 10 ppm.

(Peeling resistance test)
The photocatalyst is left in water at 30 ° C. for 1 day. The photocatalytic particles are peeled off, and the photocatalytic activity is also reduced.

As is clear from the results of the above examples, according to the embodiment, it is possible to provide a photocatalytic composite material having excellent catalytic activity, a method for producing the same, and a photocatalytic apparatus including the photocatalytic composite material.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

10 ... Photocatalyst composite material, 11 ... Substrate, 12 ... Photocatalyst layer, 21 ... First photocatalyst particles, 22 ... Second photocatalyst particles, 30 ... Photocatalyst device, 31 ... Photocatalyst composite material, 32 ... Light irradiation member, 33 ... Group A member that supplies a photocatalytic substance to a material, 34 ... Reaction chamber

Claims (19)

When a base material and a photocatalyst layer containing photocatalyst particles are provided, and the substrate-side interface of the photocatalyst layer is S _b and the opposite interface is St, the average particle diameter _{r b} of the photocatalyst particles in the vicinity of S _b is , A photocatalyst composite material smaller than the average particle diameter _rt of the photocatalyst particles in the vicinity of _St.
A photocatalyst composite material in which the photocatalyst layer further contains silver nanowires of 1/10000 to 1/10 times the total mass of the photocatalyst particles . A base material and a photocatalyst layer containing photocatalyst particles are provided, and the substrate-side interface of the photocatalyst layer is S. _b , S on the opposite interface _t When, the above S _b Average particle size r of the photocatalytic particles in the vicinity _b However, the above S _t Average particle size r of the photocatalytic particles in the vicinity _t A photocatalytic composite that is smaller than
A photocatalytic composite material having an arithmetic mean roughness of the surface of the substrate of 0.2 to 20 μm. A base material and a photocatalyst layer containing photocatalyst particles are provided, and the substrate-side interface of the photocatalyst layer is S. _b , S on the opposite interface _t When, the above S _b Average particle size r of the photocatalytic particles in the vicinity _b However, the above S _t Average particle size r of the photocatalytic particles in the vicinity _t A photocatalytic composite that is smaller than
A photocatalyst composite material in which the photocatalyst layer contains photocatalyst particles having different chemical compositions. The photocatalyst composite material according to any one of claims 1 to 3, wherein the particle size distribution curves of all the photocatalyst particles contained in the photocatalyst layer have two or more peaks. The photocatalytic composite material according to any one of claims 1 to 4, wherein the _rb is 2 to 50 nm and the _rt is 40 to 500 nm. The photocatalytic composite material according to any one of claims 1 to 5, wherein the photocatalytic particles contain a metal oxide selected from the group consisting of tungsten oxide, titanium oxide, zinc oxide, niobium oxide, and tin oxide. The photocatalyst composite material according to any one of claims 1 to 6, wherein the photocatalyst layer contains 20 to 100% by mass of the photocatalyst particles based on the total mass of the photocatalyst layer. 13 . The photocatalyst composite material according to any one item. The photocatalyst composite material according to any one of claims 1 to 8, further comprising a base layer between the base material and the photocatalyst layer. The photocatalytic composite material according to claim 9, wherein the base layer contains an inorganic oxide. Claims 1 to 1 , which include a step of applying a dispersion liquid containing first photocatalyst particles on a substrate and a step of applying a dispersion liquid containing second photocatalyst particles having an average particle size larger than that of the first photocatalyst particles. 10. The method for producing a photocatalyst composite material according to any one of 10 . The method for producing a photocatalyst composite material according to claim 11, wherein the total weight of the first photocatalyst particles deposited on the substrate is less than the total weight of the second photocatalyst particles deposited on the substrate. .. The photocatalytic composite material according to claim 11 or 12, wherein the zeta potential of the first photocatalyst particle measured in water at pH 6 and the zeta potential of the first photocatalyst particle measured in the same manner have different reference numerals. Production method. Prior to applying the dispersion liquid containing the first photocatalyst particles, a step of forming an underlayer on the substrate is further provided, and the zeta potential of the material constituting the underlayer, measured in water at pH 6, is determined. The method for producing a photocatalyst composite material according to any one of claims 11 to 13, which has a code different from the zeta potential of the first photocatalyst particles measured in the same manner. The photocatalyst composite material according to any one of claims 1 to 10 and
A light irradiation member that causes photocatalytic activity on the substrate,
A photocatalyst device including a supply member that supplies a substance to be treated to the photocatalyst composite material.
The photocatalytic composite material, whose catalytic activity is generated by the light, promotes a chemical reaction for treating the substance.
Photocatalytic device. The photocatalyst device according to claim 15, wherein the light irradiation member is an LED. The photocatalytic device according to claim 15 or 16, wherein the supply member is a fan. The photocatalyst device according to any one of claims 15 to 17, wherein the substance is supplied to the front surface of the photocatalyst composite material, and the product produced by the chemical reaction is released from the back surface of the photocatalyst composite material. The photocatalyst device according to any one of claims 15 to 18, wherein the photocatalyst layer further contains an adsorbent for adsorbing the substance.

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