Nanotube-shaped titania and process for producing the same

• US 7,687,431 B2
• Filed: 09/15/2006
• Issued: 03/30/2010
• Est. Priority Date: 03/19/2004
• Status: Active Grant

• Current Assignee: Nano Precision Medical, Inc.
• Original Assignee: Nippon Oil Corporation (ENEOS Holdings, Inc.), Kanagawa Academy of Science and Technology
• Inventors: Nakayama, Keisuke, Masuda, Hideki, Kubo, Takaya, Nishikitani, Yoshinori
• Primary Examiner(s): Hailey; Patricia L
• Application Number:
  US11/532,263
• Publication Number:
  US 20100006134A1
• Time in Patent Office: 1,292 Days
• Field of Search: 502/355, 977/810, 977/811, 977/823, 977/832, 977/948, 428/34.1, 428/34.4, 428/34.5, 423610-612
• US Class Current: 502/355
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 35/50 characterised by their shape or configuration
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 23/053 Producing by wet processes, e.g. hydrolysing titanium salts
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2004/13 Nanotubes
• CPC Class Codes: C01P 2004/54 Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
• CPC Class Codes: C25D 11/34 of metals or alloys not provided for in groups C25D11/04 - C25D11/32
• CPC Class Codes: H01G 9/2031 comprising titanium oxide, e.g. TiO2 H01G9/2036 takes precedence
• CPC Class Codes: Y02E 10/542 Dye sensitized solar cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10S 977/81 Of specified metal or metal alloy composition
• CPC Class Codes: Y10S 977/811 Of specified metal oxide composition, e.g. conducting or semiconducting compositions such as ITO, ZnOx
• CPC Class Codes: Y10S 977/813 Of specified inorganic semiconductor composition, e.g. periodic table group IV-VI compositions
• CPC Class Codes: Y10S 977/832 having specified property, e.g. lattice-constant, thermal expansion coefficient
• CPC Class Codes: Y10S 977/948 Energy storage/generating using nanostructure, e.g. fuel cell, battery
• CPC Class Codes: Y10T 428/13 Hollow or container type article [e.g., tube, vase, etc.]
• CPC Class Codes: Y10T 428/131 Glass, ceramic, or sintered, fused, fired, or calcined metal oxide or metal carbide containing [e.g., porcelain, brick, cement, etc.]
• CPC Class Codes: Y10T 428/1314 Contains fabric, fiber particle, or filament made of glass, ceramic, or sintered, fused, fired, or calcined metal oxide, or metal carbide or other inorganic compound [e.g., fiber glass, mineral fiber, sand, etc.]
• CPC Class Codes: Y10T 428/298 Physical dimension

Abstract

A nanotube-shaped titania having an aspect ratio of 6 or greater can be produced by anodizing a titanium metal or an alloy containing mainly titanium in an electrolyte solution containing a halogen atom-containing ion, such as a perchloric acid aqueous solution.

Claims

1. A nanotube-shaped titania with a diameter of 30 to 500 nm, a length of 0.9 to 100 μ

m and an aspect ratio of 30 or greater, obtained by anodizing a titanium metal or an alloy mainly containing titanium.

2. A catalyst comprising the nanotube-shaped titania according to claim 1 as a catalyst or a catalyst support.

3. The catalyst according to claim 2 wherein it is a photocatalyst.

4. A photoelectric conversion device wherein the nanotube-shaped titania according to claim 1 is used as an electrode material.

5. The photoelectric conversion device according to claim 4 wherein a dye is adsorbed on the surface of the titania.

6. A process for producing a nanotube-shaped titania with an aspect ratio of 6 or greater and a length of 0.9 to 100 μ

m, wherein a titanium metal or an alloy containing mainly titanium is anodized in an electrolyte solution containing a halogen atom-containing ion.

7. The process according to claim 6 wherein the anodization is carried out in the coexistence of a water-soluble titanium compound in the electrolyte solution containing a halogen atom-containing ion.

8. The process according to claim 6 wherein the anodization is carried out in the coexistence of an acid compound different from an acid or salt forming the halogen atom-containing ion, in the electrolyte solution containing a halogen atom-containing ion.

9. The process according to claim 6 wherein the anodization is carried out in the coexistence of titania fine particles in the electrolyte solution containing a halogen atom-containing ion.

10. The process according to claim 6 wherein the electrolyte solution is a perchloric acid aqueous solution.

11. A process of producing titania with improved crystallinity, wherein the titania produced by the process according to claim 6 is heated at a temperature of 100 to 1200°

C. for 10 to 500 minutes.