Nanotube-shaped titania and process for producing the same
View Patent ↗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.
1. A nanotube-shaped titania with a diameter of 30 to 500 nm, a length of 0.9 to 100 μm 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 μm, 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.