Method for manufacturing photocatalytic components

Abstract

To provide a method for producing photocatalysts with high industrial productivity. [Solution] The method for manufacturing a photocatalytic member comprises the steps of forming a base layer having at least cerium oxide on a substrate and forming a photocatalytic layer having at least titanium oxide, wherein the steps of forming the base layer and forming the photocatalytic layer are performed by sputtering.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a photocatalyst member.

Background Art

[0002] Photocatalysts that exhibit a catalytic action under light such as ultraviolet rays and visible light are currently attracting attention due to their various effects. As effects of photocatalysts, in particular, as seen in the Honda-Fujishima effect, hydrogen / oxygen generation by photocatalytic decomposition of water, strong oxidizing properties due to the generation of active oxygen on the surface, and super hydrophilicity due to the generation of a large number of hydroxyl groups on the surface are known. Photocatalysts have various applications, such as sterilizing viruses and pathogenic bacteria such as the novel coronavirus, which has been particularly popular in recent years, by light irradiation, decomposing formaldehyde, which is the cause of sick houses, and applying anti-fog films using super hydrophilicity.

[0003] In addition, when a photocatalyst is applied to an antireflection film, it is expected to be effective in decomposing fingerprint marks adhering to the surface of the antireflection film. In particular, an antireflection film made of a dielectric multilayer film in which inorganic substances having different refractive indices and a thickness of 1 μm or less are alternately laminated uses light interference. Therefore, even if a transparent foreign substance such as a slight fingerprint mark adheres to the surface, the interference effect is disrupted and the transparent foreign substance is easily visible. Conventionally, the antireflection film has been covered with a substance having a low surface energy such as a fluorine compound to suppress the adhesion of transparent foreign substances such as fingerprint marks, but the effect is not sufficient, and cleaning such as wiping is also required. If the transparent foreign substance, which is an organic substance, can be decomposed by the photocatalyst for such problems, cleaning will not be required, so the photocatalyst is highly expected.

[0004] Titanium dioxide is known as a material with photocatalytic properties. Vacuum thin-film formation techniques such as sputtering are known methods for forming titanium dioxide on the surface of a substrate. However, for titanium dioxide to exhibit photocatalytic properties, crystallization into anatase or rutile type is necessary, and crystallization requires heat treatment of 300°C or higher during or after film formation. For this reason, it is difficult to apply photocatalysts to materials such as plastics that have low heat resistance. Another method has been proposed in which crystallized titanium dioxide fine powder is coated onto a substrate with a binder and immobilized. This coating method does not require heating or other treatments and can be used for large-area treatment, so it is used very widely, and most photocatalysts currently on the market are produced using this coating method. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-308729 [Patent Document 2] Japanese Patent Publication No. 2007-314835 [Patent Document 3] Patent No. 5217023 [Patent Document 4] Japanese Patent Publication No. 2000-345320 [Patent Document 5] Patent No. 4460537 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the binders used to fix the photocatalyst to the substrate are often organic, and when they come into contact with the photocatalyst, a phenomenon called chalking occurs, which causes the binder to decompose and the photocatalyst itself to fall off. In addition, if the ratio of binder is increased to strengthen the bond between the substrate and the photocatalyst, the ratio of photocatalyst decreases relatively, resulting in reduced catalytic performance.

[0007] Therefore, it is desirable to form titanium oxide thin films using a vacuum thin-film formation method that does not include binders, but the challenge is how to achieve photocatalytic performance by forming films at room temperature.

[0008] Patent Document 1 discloses a method for obtaining titanium oxide crystallized at room temperature, which involves using a single cathode or dual cathode and setting the duty cycle of the applied voltage to a certain value or less. Although Patent Document 1 states that titanium oxide crystallized can be obtained using this method, the inventors conducted reproduction experiments and could not confirm crystallization, suggesting that it may depend on the equipment configuration and other factors.

[0009] Furthermore, Patent Documents 2 and 3 disclose a method for promoting crystallization by separating the deposition and oxidation treatment of a titanium metal film into two separate processes. However, this requires a complex equipment configuration and is difficult to implement with general-purpose sputtering equipment.

[0010] As an example using a general-purpose sputtering apparatus, as shown in Patent Document 4, a method has been attempted in which water is added during film formation and crystallization is achieved by heat treatment at a relatively low temperature (200°C or higher). However, even though it is low-temperature crystallization, heating to 200°C or higher is required, which deforms many plastic substrates. Therefore, it has the problem of lacking versatility.

[0011] As a method for obtaining photocatalytic performance by room temperature film deposition using a general-purpose sputtering apparatus, there is a method, as shown in Patent Document 5, in which zirconium oxide is deposited as an underlayer, and then titanium oxide is deposited. This method is an excellent method that can achieve photocatalytic performance without heat treatment.

[0012] However, the deposition rate of zirconium oxide is extremely slow, and the degree of crystallization of zirconium oxide is also low. Therefore, a certain film thickness is required for it to function as a sufficient underlayer, and this, combined with the low deposition rate, resulted in low productivity. This invention was made to solve the aforementioned problems, and its objective is to explore a different substrate layer from zirconium oxide and to provide a method for producing photocatalysts with high industrial productivity. [Means for solving the problem]

[0013] The inventors of this invention have diligently studied these issues and arrived at the present invention. Specifically, by using cerium oxide as a base layer, a cerium oxide layer crystallized with a high film deposition rate and an extremely thin film thickness was formed, and a titanium oxide layer deposited on top of it was given extremely high photocatalytic performance without heat treatment.

[0014] Specifically, a base layer is formed containing, for example, cerium oxide (CeO2) or other elements not exceeding 10 atomic percent relative to the cerium element of cerium oxide. Then, a photocatalytic layer is formed containing titanium oxide (TiO2) or titanium oxide, or other elements not exceeding 10 atomic percent relative to the titanium element of titanium oxide. It was found that the photocatalytic layer exhibits photocatalytic properties without heat treatment.

[0015] The underlying layer of the present invention is preferably composed solely of cerium oxide, but other elements may be included as long as the crystallinity of cerium oxide can be maintained. In particular, in sputtering, cerium oxide may be mixed with other metals to form a composite target in order to achieve a stable discharge. In this case, the metal may be incorporated into the film during deposition, but this is acceptable as long as the crystallinity of cerium oxide can be maintained. The thickness of the underlying layer is not particularly limited; for example, it has been shown to be effective even at 10 nm. However, if the substrate is a plastic film or the like, the surface may not be smooth, so it is desirable for the underlying layer to be 20 nm or thicker. A thickness of 20 nm or thicker ensures the continuity of the underlying layer and maintains sufficient crystallinity. However, if the thickness of the underlying layer exceeds 100 nm, it not only places a thermal load on the substrate but is also industrially inefficient, so it is preferable to keep it below 100 nm.

[0016] The photocatalytic layer of the present invention is composed of titanium oxide (TiO2), but other elements may be contained in addition to titanium oxide as long as photocatalytic performance is exhibited. For example, titanium oxide has a band gap in the ultraviolet region and requires ultraviolet light to operate as a photocatalyst. There is an example where nitrogen is added to make it responsive to visible light. In the present invention, nitrogen can also be added to make a visible-light-responsive photocatalyst. Further, a metal element, for example niobium, may be added to enhance the electrical conductivity of the photocatalytic layer. The thickness of the photocatalytic layer is not particularly limited, but it is preferably 20 nm or more where photocatalytic performance is clearly exhibited. Also, even if the thickness of the photocatalytic layer is large, the effects of the present invention can be obtained, but industrially it is desirable to be 200 nm or less.

[0017] Furthermore, in the present invention, there may be a layer other than the base layer and the photocatalytic layer. For example, silicon oxide may be formed on the surface of the photocatalytic layer for the purpose of maintaining the super hydrophilicity of the photocatalyst. Also, a conductive layer may be formed before forming the base layer in order to use the present invention as a photocatalytic electrode as seen in the Honda-Fujishima effect. In any case, the present invention is completed by forming a photocatalytic layer containing titanium oxide on the side opposite to the substrate with respect to the base layer containing cerium oxide. The gist of the present invention is as follows.

[0018] According to an aspect of the present invention, there is provided a photocatalytic member in which a photocatalytic layer is formed on a substrate via a base layer, the base layer having at least cerium oxide, and the photocatalytic layer having at least titanium oxide.

[0019] Here, the base layer may be composed of only cerium oxide or may be composed of cerium oxide and at least one or more other elements with a cerium element ratio of 10 atomic% or less.

[0020] Also, the photocatalytic layer may be composed of only titanium oxide or may be composed of titanium oxide and at least one or more other elements with a titanium element ratio of 10 atomic% or less.

[0021] Also, the thickness of the base layer may be 10 nm or more.

[0022] Also, the thickness of the photocatalyst layer may be 20 nm or more.

[0023] Also, a hydrophilic retention layer using silicon oxide or a composite oxide of silicon oxide and another metal may be provided on the photocatalyst layer.

[0024] Also, the substrate may be transparent.

[0025] Also, the substrate may be a polymer film.

Advantages of the Invention

[0026] According to the present invention, a method for manufacturing a photocatalyst with high industrial productivity can be provided.

Brief Description of the Drawings

[0027] [Figure 1] It is a graph showing an example of an XRD spectrum. [Figure 2] It is a cross-sectional view showing an outline of the photocatalyst member according to the present invention.

Embodiments for Carrying Out the Invention

[0028] <1. Comparison between cerium oxide and zirconium oxide> The cerium oxide used in the present invention is compared with the zirconium oxide used in Patent Document 5. First, the crystallinity when forming a film on each material is compared.

[0029] An RF sputtering apparatus was used for film formation. The exhaust system is composed of a turbo molecular pump and a rotary pump, and 5×10 , [Figure 2] , [Figure 1] , ,

[0027] , , , , , ,

[0029] , , , ,

[0028] , -4 , , , The vacuum chamber can be evacuated to below Pa. The chamber has four cathodes, each capable of holding a 2-inch diameter target material. A shutter mechanism is installed between each cathode, and its opening and closing time can be controlled by a timer. Therefore, if the deposition rate is known in advance, the film thickness can be precisely controlled by controlling the shutter opening time. Gas supply piping is connected to the vacuum chamber, allowing for the supply of argon, oxygen, and nitrogen gases. The flow rate of each gas can be precisely controlled by a mass flow meter installed between the gas cylinder and the vacuum chamber. A conductance valve is installed between the turbomolecular pump and the vacuum chamber, allowing for adjustment of the deposition pressure to any desired level by adjusting the pumping speed. The substrate can be placed on a stage facing the target. The stage can rotate to ensure uniform film thickness and can be heated up to 300°C. Furthermore, the distance between the stage and the target is also adjustable.

[0030] After placing the silicon substrate on the stage inside the RF sputtering apparatus as described above, 5 × 10 -4 The system was evacuated until the pressure dropped below Pa, and then argon and oxygen gases were introduced. The ratio of argon to oxygen gases was determined by investigating conditions that would not cause absorption in the visible light region.

[0031] For cerium oxide film deposition, a target was used that was formed by sintering cerium oxide and shaping it into a target form. For zirconium oxide, metallic zirconium was used as the target. It is generally known that metal targets result in faster film deposition rates than oxide targets.

[0032] A 2-inch target was subjected to 200W of RF power, and a film was deposited on a silicon substrate for a certain period of time. The film thickness was evaluated using spectroscopic ellipsometry (M-2000 JAWoollam). Ellipsometry provides the amplitude ratio Ψ and phase difference Δ of p-polarized and s-polarized light for each wavelength. By applying an appropriate optical model to these values ​​and fitting it, including the film thickness as a parameter, the film thickness can be obtained along with the optical constants. The film thickness was determined based on the measurement results at the center of the silicon substrate. Table 1 shows the film thickness divided by the deposition time.

[0033] [Table 1]

[0034] As is clear from Table 1, cerium oxide has more than twice the film deposition rate compared to zirconium oxide.

[0035] Furthermore, to compare the crystallinity of each material, films were deposited on glass substrates and evaluated by XRD. To avoid the influence of the substrate on the crystallization of the thin films, alkali-free glass (OA-10G, manufactured by Nippon Electric Glass) was used. The substrates were washed with water using a neutral detergent, then ultrasonically cleaned in ethanol solution for 10 minutes. After removing them from the solution, droplets were immediately removed with an air gun to prevent drying stains.

[0036] The cleaned alkali-free glass was placed on the stage in the RF sputtering apparatus described above, and the deposition time was adjusted based on the deposition rates in Table 1 to achieve a film thickness of 50 nm. Crystallinity was then evaluated by XRD. XRD was performed using an X'Pert PRO MPD (PANalytical) with Cuα as the radiation source and an incidence angle of 1°. The XRD results are shown in Figure 1.

[0037] As shown in Figure 1, zirconium oxide shows a slight peak around 28°. In contrast, cerium oxide has a sharp peak at the same position, as well as peaks at 33°, 47°, and 56°. Therefore, cerium oxide is superior in terms of crystallinity. Figure 1 also shows the results for hafnium oxide for comparison. Hafnium is located directly below zirconium in the periodic table, and its properties are expected to be similar to zirconium, but it does not crystallize.

[0038] Partial heteroepitaxial growth is considered a factor in the formation of a substrate layer that gives titanium dioxide photocatalytic properties. It is thought that the substrate layer forms a crystal lattice, and the titanium dioxide grows in accordance with its crystallites. Therefore, if the substrate layer undergoes clear crystallization with a thin film thickness, it is thought that this will promote the crystallization of the titanium dioxide in the photocatalytic layer that is subsequently deposited. Based on the above results, preferred embodiments of the present invention will be described in detail below with reference to the drawings.

[0039] <2. Photocatalytic component according to this embodiment> Figure 2 is a schematic cross-sectional view showing the configuration of the photocatalytic member 1 according to the present invention. The photocatalytic member 1 according to this embodiment is a photocatalytic member in which a photocatalytic layer 4 is formed on a substrate 2 via an underlayer 3, wherein the underlayer 3 has at least cerium oxide and the photocatalytic layer 4 has at least titanium oxide.

[0040] <3. Base material> The base material 2 of the present invention may be composed of any material. Examples of materials for the base material 2 include glass, metal, resin, and ceramics. In particular, resin films with a thin resin thickness have many advantages, such as being lightweight and being able to be laminated to various surfaces. Furthermore, for industrial reasons, they have the advantage of being able to be continuously deposited using a roll-to-roll sputtering device for mass production. In addition, transparent resin (polymer) films may be used when used in places where light transmission is required, such as window glass and displays.

[0041] While there are no particular limitations on the material used for the transparent resin film, examples include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyaramid, polyimide, polycarbonate, polyethylene, polypropylene, triacetylcellulose (TAC), and polycycloolefin (COC, COP). The thickness of the base material 2 is not particularly limited, but if the base material 2 is a resin film, it is desirable to set it to 20 μm or more and 200 μm or less, considering ease of handling during manufacturing and the thinning of the component. Furthermore, from the viewpoint of improving the abrasion resistance of the base material 2, a coating of, for example, acrylic resin may be formed on at least one surface of the base material 2, for example, by solution coating. Alternatively, an acrylic resin in which organic or inorganic particles are dispersed for the purpose of improving the degree of cloudiness and film running performance may be used.

[0042] <4. Base layer> The base layer 3 is a layer that promotes the crystallization of the photocatalytic layer 4, which is the objective of this embodiment. The base layer 3 contains cerium oxide. More specifically, the base layer 3 is composed solely of cerium oxide, or of cerium oxide and at least one other element in a total cerium element ratio of 10 atomic percent or less. However, this composition is merely an example, and it is sufficient that the base layer 3 contains cerium oxide. The elements contained in the base layer 3 can be measured, for example, by X-ray microanalyzer (XMA) or X-ray fluorescence analysis (XRF).

[0043] The manufacturing method for the base layer 3 can be any method. However, from the perspective of layering dissimilar materials to form a multilayer film, the sputtering method is effective. A thickness of at least 10 nm is desirable. Furthermore, considering the effects of surface roughness of the substrate 2, a thickness of 20 nm or more is desirable. The thickness of the base layer 3 can be measured, for example, by creating a cross-sectional section of the sample using the microtome method and measuring it with a transmission electron microscope. If the thickness of the base layer 3 is 20 nm or more, the continuity of the base layer 3 can be more reliably ensured even if the surface of the substrate 2 is rough. On the other hand, film deposition of 100 nm or more not only places a thermal load on the substrate 2 but is also industrially inefficient, so it is desirable to keep it below 100 nm. It is desirable that the base layer 3 be composed only of cerium oxide, but other elements may be included as long as its crystallinity can be maintained. In particular, when cerium oxide and other metals are mixed to create a composite target in order to achieve a stable discharge during sputtering, the metal may be incorporated into the film during deposition. Even in such cases, it is acceptable as long as the crystallinity of the base layer 3 can be maintained. Other examples of metals include zinc (Zn) and aluminum (Al).

[0044] <5. Photocatalyst layer> The photocatalytic layer 4 is a layer that functions as a photocatalyst. The photocatalytic layer 4 contains titanium dioxide as a photocatalyst. More specifically, the photocatalytic layer 4 is composed solely of titanium dioxide, or of titanium dioxide and at least one other element in a total titanium element ratio of 10 atomic percent or less. However, this configuration is merely an example, and it is sufficient for the photocatalytic layer 4 to contain titanium dioxide to an extent that the effects of this embodiment can be obtained. The elements contained in the photocatalytic layer 4 can be measured, for example, by X-ray microanalyzer (XMA) or X-ray fluorescence analysis (XRF).

[0045] Any method may be used to manufacture the photocatalytic layer 4. However, sputtering is effective from the perspective of stacking dissimilar materials to form a multilayer film. The thickness of the photocatalytic layer 4 should preferably be at least 20 nm in order for the photocatalytic layer 4 to function as a photocatalyst. The thickness of the photocatalytic layer 4 can be measured, for example, by creating a cross-sectional section of the sample using a microtome and measuring it with a transmission electron microscope. There is no particular upper limit set for the thickness, but since titanium dioxide has a slow film deposition rate, it is desirable from an industrial productivity standpoint to keep it below 200 nm. The photocatalytic layer 4 may contain other elements as long as they exhibit photocatalytic performance. For example, titanium dioxide has a band gap in the ultraviolet region and requires ultraviolet light to function as a photocatalyst, but there are examples of adding nitrogen to make it responsive to visible light. In this invention as well, nitrogen can be added to create a visible-responsive photocatalyst. In addition, a metallic element, such as niobium, may be added to increase the electrical conductivity of the photocatalytic layer.

[0046] <6. Other Layers> Here, one or more layers of conductive material may be laminated between the substrate 2 and the underlayer 3 in order to give the photocatalytic member 1 conductivity. Examples of such conductive materials include indium-tin composite oxide (ITO) and aluminum-zinc composite oxide (AZO). Alternatively, a metal material may be laminated. Furthermore, a different oxide may be laminated on top of the metal material to suppress oxidation by plasma when forming the underlayer 3. In addition, an adhesion layer may be formed to ensure adhesion between the substrate 2 and the underlayer 3. Furthermore, if the substrate 2 is a transparent substrate, a transparent material may be formed to increase the transparency of the photocatalytic member 1. Furthermore, a smoothing layer may be formed to make the surface of the substrate 2 smooth.

[0047] Furthermore, a transparent material may be formed on the surface of the photocatalytic layer 4. In particular, a hydrophilic retention layer using silicon dioxide or a composite oxide of silicon dioxide and another metal may be formed on the photocatalytic layer 4 to maintain superhydrophilicity for a long time and in the dark. Also, since titanium dioxide used in the photocatalytic layer is a high refractive index material, a low refractive index material such as silicon dioxide may be laminated on the photocatalytic layer to reduce the surface reflectivity.

[0048] As explained above, according to this embodiment, since cerium oxide is used in the underlayer 3, the photocatalytic layer 4 can exhibit its photocatalytic function without heating the photocatalytic layer 4. Furthermore, cerium oxide has a fast film formation rate. Therefore, it is possible to manufacture photocatalysts with high industrial productivity. [Examples]

[0049] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. <Example 1> Alkali-free glass (OA-10G, manufactured by Nippon Electric Glass) was used as the substrate. The substrate was washed with water using a neutral detergent, then ultrasonically cleaned in ethanol solution for 10 minutes. After being removed from the solution, droplets were immediately removed with an air gun and the substrate was dried. The substrate was set in an RF sputtering apparatus, and after exhausting, film deposition was performed. A 50 nm thick layer of cerium oxide was deposited as the underlayer, and then a 50 nm thick layer of titanium oxide was laminated on top of it as a photocatalytic layer. The sample was then removed and prepared.

[0050] <Example 2> The sample was prepared under the same conditions as in Example 1, except that the thickness of the cerium oxide layer was set to 10 nm.

[0051] <Example 3> The sample was prepared under the same conditions as in Example 1, except that the thickness of the cerium oxide layer was set to 100 nm.

[0052] <Example 4> The sample was prepared under the same conditions as in Example 1, except that the thickness of the titanium dioxide layer was set to 20 nm.

[0053] <Example 5> The sample was prepared under the same conditions as in Example 1, except that the thickness of the cerium oxide layer was set to 200 nm.

[0054] <Example 6> After preparing the sample under the same conditions as in Example 1, silicon oxide was deposited to a thickness of 5 nm using a sputtering apparatus.

[0055] <Example 7> Cycloolefin polymer (COP) was used as the substrate. Before placing the substrate in the sputtering apparatus, the surface of the COP was exposed to argon plasma at 5W for 60 seconds in a vacuum apparatus capable of plasma treatment to remove surface contamination, and then the substrate was immediately set in the sputtering apparatus. Subsequently, a sample was prepared under the same conditions as in Example 1.

[0056] <Comparative Example 1> Alkali-free glass (OA-10G, manufactured by Nippon Electric Glass) was used as the substrate. The substrate was washed with water using a neutral detergent, then ultrasonically cleaned in ethanol solution for 10 minutes. After removing it from the solution, droplets were immediately removed with an air gun and the sample was dried to prepare it.

[0057] <Comparative Example 2> Alkali-free glass (OA-10G, manufactured by Nippon Electric Glass) was used as the substrate. The substrate was washed with water using a neutral detergent, then ultrasonically cleaned in ethanol solution for 10 minutes. After removing it from the solution, droplets were immediately removed with an air gun and it was dried. The substrate was set in an RF sputtering apparatus, and after exhausting the system, a 50 nm titanium oxide film was deposited, and then the sample was removed to prepare the sample.

[0058] <Comparative Example 3> A sample prepared under the same conditions as in Comparative Example 2 was heated to 300°C in an electric furnace, held for 2 hours, then the heating of the electric furnace was stopped, and the sample was cooled in the furnace until it returned to room temperature before being removed and prepared.

[0059] <Comparative Example 4> The sample was prepared under the same conditions as in Example 1, except that cerium oxide was replaced with zirconium oxide.

[0060] <Comparative Example 5> The sample was prepared under the same conditions as in Comparative Example 4, except that the thickness of the zirconium oxide layer was set to 10 nm.

[0061] <Comparative Example 6> The sample was prepared under the same conditions as in Example 1, except that cerium oxide was replaced with hafnium oxide.

[0062] <Rating> <Superhydrophilicity evaluation> The prepared samples were left undisturbed in the dark for 48 hours to eliminate the effects of ambient light. Afterward, they were removed and placed in a xenon accelerated weathering tester, Q-SUN Xe-3 (manufactured by Q-Lab Corp.). Xenon light closely matches the spectrum of sunlight, and its intensity can be controlled, allowing for accurate verification of the photocatalytic effect. Irradiance: 64 W / m² 2 (0.55W / m 2 The samples were irradiated for 1 hour at a temperature of 47°C and relative humidity of 50% using a Daylight-B / B filter at a black panel temperature of 70°C. After removal, the water contact angle was evaluated within 30 minutes to assess the presence or absence of superhydrophilicity. The water contact angle was measured using a fully automatic contact angle meter DMo-702 (manufactured by Kyowa Interface Science Co., Ltd.) by dropping 1.5 μL of pure water. The measurement was repeated three times and the average value was taken as the post-irradiation contact angle.

[0063] <Evaluation Results> <Examples 1-3> As is clear from Table 2, when the thickness of cerium oxide is in the range of 10 to 100 nm and the thickness of titanium oxide is 50 nm, the contact angle after irradiation with xenon light is 10° or less in both cases, indicating that they are in a superhydrophilic state and functioning as photocatalysts.

[0064] <Examples 4-5> Compared to Examples 1-3, even with titanium dioxide thicknesses of 20 nm and 200 nm respectively, the contact angle after xenon light irradiation was 10° or less in all cases, indicating a superhydrophilic state and demonstrating its function as a photocatalyst.

[0065] <Example 6> Even when a silicon oxide layer, which acts as a hydrophilic retention layer, is formed on the surface, the contact angle after irradiation with xenon light is less than 10°, indicating a superhydrophilic state and demonstrating that it functions as a photocatalyst.

[0066] <Example 7> The glass transition temperature of COP is 150°C, but the sample after film formation shows no deformation, indicating that it was not exposed to high temperatures. The contact angle after xenon light irradiation is less than 10°, indicating a superhydrophilic state and demonstrating its function as a photocatalyst.

[0067] <Comparative Example 1> The contact angle of the glass substrate alone does not fall below 10° after irradiation with xenon light, indicating that photocatalytic performance is not exhibited.

[0068] <Comparative Example 2> When titanium dioxide is deposited at room temperature without heat treatment, the contact angle after xenon light irradiation does not fall below 10°, indicating that photocatalytic performance is not exhibited. This clearly demonstrates that photocatalytic performance is not achieved simply by forming titanium dioxide.

[0069] <Comparative Example 3> When a film deposited under the same conditions as in Comparative Example 2 was heat-treated and irradiated with xenon light, the contact angle was less than 10°, indicating a superhydrophilic state and thus achieving photocatalytic performance. However, it is clear that a high-temperature heat treatment of 300°C is necessary.

[0070] <Comparative Example 4> When zirconium oxide was used as the underlayer instead of cerium oxide, irradiation with xenon light resulted in a contact angle of 10° or less, indicating a superhydrophilic state and thus achieving photocatalytic performance. However, as shown in Table 1, the deposition rate of zirconium oxide is slower than that of cerium oxide, resulting in lower productivity.

[0071] <Comparative Example 5> When the zirconium oxide film was thinned to 10 nm to mitigate the effects of the slow film deposition rate, the contact angle after xenon light irradiation did not fall below 10°, indicating that photocatalytic performance was not exhibited. In contrast, as shown in Example 2, cerium oxide exhibited photocatalytic performance even at a thin film thickness, demonstrating its superiority over zirconium oxide.

[0072] <Comparative Example 6> When hafnium oxide was used as the substrate instead of cerium oxide, the contact angle after xenon light irradiation did not fall below 10°, and photocatalytic performance was not exhibited. This indicates that the cerium oxide of the present invention is suitable as a substrate for exhibiting photocatalytic performance.

[0073] As described above, this embodiment provides a photocatalytic component that exhibits high productivity without heat treatment. This embodiment provides a photocatalytic component that can be used for sterilization of viruses and pathogens, decomposition of formaldehyde which causes sick building syndrome, and anti-fogging films.

[0074] Furthermore, by applying this embodiment to an optical film that utilizes the light interference effect, it is possible to impart a function to decompose organic substances such as sweat, thereby maintaining excellent optical properties at all times.

[0075] [Table 2]

[0076] Although preferred embodiments of the present invention have been described in detail above with reference to the attached drawings, the present invention is not limited to these examples. It is clear to any person with ordinary skill in the art to which the present invention belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these are also understood to fall within the technical scope of the present invention.

Claims

1. A method for manufacturing a photocatalytic component, A step of forming a base layer having at least cerium oxide on the substrate, The process includes forming a photocatalytic layer having at least titanium dioxide, A method for manufacturing a photocatalytic member, wherein the steps of forming the base layer and forming the photocatalytic layer are performed by sputtering.

2. A method for manufacturing a photocatalytic member according to claim 1, wherein no heat treatment is performed after the formation of the photocatalytic layer.

3. The method for producing a photocatalytic member according to claim 1 or 2, characterized in that the underlayer is composed solely of cerium oxide, or of cerium oxide and at least one other element in a cerium element ratio of 10 atomic percent or less.

4. A method for manufacturing a photocatalytic member according to any one of claims 1 to 3, characterized in that the photocatalytic layer is composed solely of titanium oxide, or of titanium oxide and at least one other element in a titanium element ratio of 10 atomic percent or less.

5. A method for manufacturing a photocatalytic member according to any one of claims 1 to 4, characterized in that the thickness of the underlying layer is 10 nm or more and 100 nm or less.

6. A method for manufacturing a photocatalytic member according to any one of claims 1 to 5, characterized in that the thickness of the photocatalytic layer is 20 nm or more and 200 nm or less.

7. A method for manufacturing a photocatalytic member according to any one of claims 1 to 6, comprising the step of forming a hydrophilic retaining layer on the photocatalytic layer using silicon dioxide or a composite oxide of silicon dioxide and another metal.

8. The method for manufacturing a photocatalytic member according to claim 7, wherein the step of forming the hydrophilic retaining layer is performed by sputtering.

9. A method for manufacturing a photocatalytic member according to any one of claims 1 to 8, characterized in that the substrate is transparent.

10. A method for producing a photocatalytic member according to any one of claims 1 to 9, characterized in that the substrate is a polymer film.

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