Titanium dioxide photocatalyst

• US 6,387,844 B1
• Filed: 03/17/1998
• Issued: 05/14/2002
• Est. Priority Date: 10/31/1994
• Status: Expired due to Term

• Current Assignee: Kanagawa Academy of Science and Technology, Nippon Soda Company Limited
• Original Assignee: Kanagawa Academy of Science and Technology, Nippon Soda Company Limited
• Inventors: Fujishima, Akira, Hashimoto, Kazuhito, Iyoda, Tomokazu, Yoshimoto, Tetsuo, Saitoh, Tokuyoshi, Fukayama, Shigemichi
• Primary Examiner(s): Bell, Mark L.
• Assistant Examiner(s): Hailey, Patricia L.
• Application Number:
  US09/042,609
• Time in Patent Office: 1,519 Days
• Field of Search: 502/349, 502/350, 502/232, 502/240, 502/242, 428/428, 428/432, 428/702, 427/235, 427/36, 427/255, 427/391, 427/376.2, 427/430.1
• US Class Current: 502/350
• CPC Class Codes: A61L 9/205 using a photocatalyst or photosensitiser
• CPC Class Codes: B01D 2255/20707 Titanium
• CPC Class Codes: B01D 2255/802 Photocatalytic
• CPC Class Codes: B01J 21/06 Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 21/066 Zirconium or hafnium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 35/30 characterised by their physical properties
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 37/0244 Coatings comprising several layers
• CPC Class Codes: C03C 17/2456 Coating containing TiO2
• CPC Class Codes: C03C 17/256 Coating containing TiO2
• CPC Class Codes: C03C 17/3417 all coatings being oxide coatings
• CPC Class Codes: C03C 2217/212 TiO2
• CPC Class Codes: C03C 2217/71 Photocatalytic coatings
• CPC Class Codes: H01J 61/35 provided with coatings on the walls thereof; Selection of materials for the coatings using coloured coatings H01J61/40; using luminescent coatings H01J61/42
• CPC Class Codes: H01J 61/42 by transforming the wavelength of the light by luminescence

Abstract

A titanium dioxide film having at least photocatalytic activity, whose light linear transmittance corresponding to light having a wavelength of 550 nm is not less than 50 % and whose thickness is 0.1 to 5 μm or so, is formed on a transparent substrate constituted by a glass plate or the like. Preferably, a precoat film, which has optical transmissivity and is constituted by a SiO₂ film having a thickness of 0.02 to 0.2 μm or so, is provided between the transparent substrate and the titanium dioxide film. Thereby, excellent photocatalytic action and optical transmissivity can be obtained. Moreover, members composing various structures such as a glass window, which are especially required to have optical transparency, can be further provided with photocatalytic activities.

Claims

1. A titanium dioxide photocatalyst structure comprising:

a transparent glass substrate having first and second opposing surfaces, said transparent glass substrate containing alkaline ingredients therein, the first surface of said substrate receiving light from an external light source;

a titanium dioxide film having first and second opposing surfaces, a light transmittance of said titanium dioxide film being at least 50% for light having a wavelength of 550 nm, the first surface of said titanium dioxide film being formed on the second surface of said substrate, whereby light transmitted from said external source through the first and second opposing surfaces of said substrate and through the first surface of said titanium dioxide film to the second surface thereof causes photocatalytic activity to be generated on the second surface of said titanium dioxide film; and

a transparent precoat film interposed between the second surface of said substrate and the first surface of said titanium dioxide film.

2. The titanium dioxide photocatalyst structure according to claim 1, wherein said transparent precoat film has a thickness of 0.02 μ

m to 0.2 μ

m.

3. The titanium dioxide photocatalyst structure according to claim 2, wherein said precoat film is composed of SiO₂.

4. A titanium dioxide photocatalyst structure comprising:

a transparent substrate;

a titanium dioxide film formed on said substrate, said titanium dioxide film having photocatalytic activity and a light transmittance of at least 50% for light having a wavelength of 550 nm; and

a transparent precoat film disposed between the transparent substrate and the titanium dioxide film.

5. The titanium dioxide photocatalyst structure according to claim 4 wherein the precoat film has a thickness of 0.02 μ

m to 0.2 μ

m.

6. The titanium dioxide photocatalyst structure according to claim 4 wherein the precoat film is composed of SiO₂.

7. A method for producing a titanium dioxide photocatalyst structure according to claim 4 comprising a producing process which includes the step of forming the titanium dioxide film on the transparent substrate by a method selected from the group consisting of a pyro-sol method, a dipping method, a printing method and a CVD method.

8. A titanium dioxide photocatalyst structure comprising:

a transparent substrate;

a titanium dioxide film formed on said substrate, said titanium dioxide film having a thickness of 0.1 μ

m to 5 μ

m, photocatalytic activity and a light transmittance of at least 50% for light having a wavelength of 550 nm; and

a transparent precoat film disposed between the transparent substrate and the titanium dioxide film.

9. The titanium dioxide photocatalyst structure according to claim 8 wherein the precoat film has a thickness of 0.02 μ

m to 0.2 μ

m.

10. The titanium dioxide photocatalyst structure according to claim 8 wherein the precoat film is composed of SiO₂.

11. A titanium dioxide photocatalyst structure comprising:

a transparent substrate;

a titanium dioxide film, containing an anatase crystal, formed on said substrate, said titanium dioxide film having photocatalytic activity and a light transmittance of at least 50% for light having a wavelength of 550 nm; and

a transparent precoat film disposed between the transparent substrate and the titanium dioxide film.

12. The titanium dioxide photocatalyst structure according to claim 11 wherein the precoat film has a thickness of 0.02 μ

m to 0.2 μ

m.

13. The titanium dioxide photocatalyst structure according to claim 11 wherein the precoat film is composed of SiO₂.