Photocatalyst

• US 6,743,749 B2
• Filed: 07/26/2002
• Issued: 06/01/2004
• Est. Priority Date: 01/27/2000
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation)
• Original Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation)
• Inventors: Asahi, Ryoji, Shiga, Takahiro, Morikawa, Takeshi, Ohwaki, Takeshi, Taga, Yasunori
• Primary Examiner(s): Bell, Mark L.
• Assistant Examiner(s): Hailey, Patricia L.
• Application Number:
  US10/181,918
• Publication Number:
  US 20030013607A1
• Time in Patent Office: 676 Days
• Field of Search: 502/349, 502/350, 502/326, 502/200, 502/216, 502/222, 502/223, 502/242, 423/239.1, 423/610
• US Class Current: 502/349
• 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 23/26 Chromium
• CPC Class Codes: B01J 27/24 Nitrogen compounds
• CPC Class Codes: B01J 35/30 characterised by their physical properties
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 37/347 Ionic or cathodic spraying; Electric discharge

Abstract

A Ti—O—N film is formed on an SiO₂ substrate by sputtering. For example, TiO₂ is used as a target and nitrogen gas is introduced into the atmosphere. Crystallization is carried out by a post-sputtering heat treatment. Then a charge separation material such as Pt is supported on the Ti—O—N film. With the fabricated TiO₂ crystals, the Ti—O—N film containing nitrogen exhibits a good catalytic reaction by using visible light as acting light. Since the charge separation material captures electrons or positive holes, recombination of electrons and positive holes is effectively prevented, and consequently more efficient photocatalytic reaction is performed. It is preferable to form a photocatalyst material film (Ti—Cr—O—N film) by sputtering the SiO₂ substrate by use of TiO₂ and Cr as the target in a nitrogen atmosphere. Crystallization is performed by a post-sputtering heat treatment.

Claims

1. A photocatalyst comprising:

a titanium compound in which a nitrogen atom or a sulfur atom is substituted for a portion of oxygen sites of a titanium oxide crystal, in which the same is doped at an interstitial site of the crystal lattices of titanium oxide, or, in which the same is placed at a grain boundary of a polycrystalline body of the titanium oxide crystals; and

a charge separation material partially supported on the surface of the titanium compound.

3. A photocatalyst according to claim 1 or 2, wherein

the charge separation material is at least one metal selected from the group consisting of Pt, Pd, and Ni.

4. A photocatalyst according to claim 1 or 2, wherein

the charge separation material is at least one oxide selected from the group consisting of RuO₂, NiO₂, SnO₂, Al₂O₃, ZnO, and SiO₂.

2. A photocatalyst comprising:

a titanium compound in which a nitrogen atom or a sulfur atom is substituted for a portion of oxygen sites of a titanium oxide crystal, in which the same is doped at an interstitial site of the crystal lattices of the titanium oxide, or, in which the same is placed at a grain boundary of the polycrystalline body of the titanium oxide crystals, and in which at least one of vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, ruthenium, rhodium, rhenium, osmium, palladium, platinum, and iridium is substituted for a metal site of the titanium oxide crystal, in which the same is doped at an interstitial site of the crystal lattices of titanium oxide, or, in which the same is placed at a grain boundary of the polycrystalline body of titanium oxide crystals; and

a charge separation material partially supported on the surface of the titanium compound.

5. A photocatalyst comprising:

a titanium compound in which a nitrogen atom is substituted for a portion of oxygen sites of titanium oxide crystal, in which the same is doped at an interstitial site of the crystal lattices of titanium oxide, or, in which the same is placed at a grain boundary of the polycrystalline body of titanium oxide crystals; and

at least one of Pt, Pd, Ni, RuO₂, NiO₂, SnO₂, Al₂O₃, ZnO, and SiO₂ is partially supported on the surface of the titanium compound.

6. A photocatalyst comprising:

an inner material comprising a titanium compound in which a nitrogen atom or a sulfur atom is substituted for a portion of oxygen sites of a titanium oxide crystal, in which the same is doped at an interstitial site of the crystal lattices of the titanium oxide crystal, or, in which the same is placed at a grain boundary of polycrystalline body of the titanium oxide crystal;

a titanium oxide layer formed on the surface of the inner material; and

a charge separation material partially supported on the surface of the titanium oxide layer.

8. A photocatalyst according to claim 6 or 7, wherein

the compositional ratios in the titanium oxide layer and in the inner material gradually change from the front surface towards the inside.

7. A photocatalyst comprising:

an inner material comprising a titanium compound in which a nitrogen atom or a sulfur atom is substituted for a portion of the oxygen sites of 2 titanium oxide crystal, in which the same is doped at an interstitial site of crystal lattices of the titanium oxide, or, in which the same is placed at a grain boundary of the polycrystalline body of titanium oxide crystal, and in which at least one of vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, ruthenium, rhodium, rhenium, osmium, palladium, platinum, and iridium substitutes for a portion of the metal sites of the titanium oxide crystal, in which the same is doped at an interstitial site of the crystal lattices of titanium oxide, or, in which the same is placed at a grain boundary of a polycrystalline body of the titanium oxide crystal;

a titanium oxide layer formed on the surface of the inner material; and

a charge separation material is partially supported on the titanium oxide layer.

9. A photocatalytic material comprising:

an oxide crystal of a metal element M1 having a photocatalytic function in which a nitrogen atom or a sulfur atom is substituted for a portion of oxygen sites, in which the same is doped at an interstitial site of the crystal lattices of an oxide, or, in which the same is placed at a grain boundary of a polycrystalline body of the oxide crystal; and

at least one metal element M2 of vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, ruthenium, rhodium, rhenium, osmium, palladium, platinum, iridium, niobium, and molybdenum which substitutes for a portion of the M1 sites of the oxide crystal, in which the same is doped at an interstitial site of the crystal lattices of the oxide, or, in which the same is placed at a grain boundary of a polycrystalline body of the oxide crystal.

10. A photocatalytic material according to claim 9, wherein

the metal element M1 is any one of titanium, zinc, and tin.

11. A photocatalyst comprising:

an inner material comprising a photocatalytic material according to either claim 9 or 10; and

an outer material formed on the surface of the inner material, the outer material comprising a titanium oxide layer or a titanium oxide layer containing nitrogen or sulfur.

12. A photocatalyst according to claim 11, wherein

the compositional ratios in the outer material and in the inner material gradually change according to the distance from the front surface.