Visible light activatable photocatalyst

• US 8,551,909 B2
• Filed: 03/09/2009
• Issued: 10/08/2013
• Est. Priority Date: 03/10/2008
• Status: Active Grant

• Current Assignee: Kastus Technologies Designated Activity Company
• Original Assignee: Dublin Institute of Technology
• Inventors: Etacheri, Vinodkumar, Pillai, Surresh C., Colreavy, John
• Primary Examiner(s): Hailey, Patricia L
• Application Number:
  US12/736,118
• Publication Number:
  US 20110028311A1
• Time in Patent Office: 1,674 Days
• Field of Search: 502/5, 502/350, 423610-612
• US Class Current: 502/350
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 23/745 Iron
• CPC Class Codes: B01J 27/12 Fluorides
• CPC Class Codes: B01J 27/16 containing oxygen , i.e. acids, anhydrides and their derivates with N, S, B or halogens without carriers or on carriers based on C, Si, Al or Zr; also salts of Si, Al and Zr
• CPC Class Codes: B01J 27/24 Nitrogen compounds
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 35/615 100-500 m2/g
• CPC Class Codes: B01J 35/647 2-50 nm
• CPC Class Codes: B01J 37/0215 Coating
• CPC Class Codes: B01J 37/346 of microwave energy
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 23/047 Titanium dioxide
• CPC Class Codes: C01G 23/053 Producing by wet processes, e.g. hydrolysing titanium salts
• CPC Class Codes: C01P 2002/52 containing elements as dopants
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2002/82 by IR- or Raman-data
• CPC Class Codes: C01P 2002/84 by UV- or VIS- data
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/16 Pore diameter

Abstract

A visible light activatable mesoporous titanium dioxide photocatalyst having a surface area of from 100 m²/g to 400 m²/g. The photocatalyst may have a rate of decomposition greater than 0.005 min⁻¹. The photocatalyst may have a band gap width less than 2.95 eV. The photocatalyst may comprise undoped titanium dioxide or doped titanium dioxide. A hydrothermal process for synthesising a photocatalyst is also described.

Claims

1. A visible light activatable mesoporous anatase phase titanium dioxide photocatalyst having a surface area of from 200 m²/g to 300 m²/g, and a band gap width of less than 2.95 eV and a rate of decomposition greater than 0.007 min⁻

1 at a wavelength of 450 nm.

2. The photocatalyst as claimed in claim 1 wherein the photocatalyst has a band gap width of 2.9 eV or less.

3. The photocatalyst as claimed in claim 1 comprising undoped titanium dioxide.

4. The photocatalyst as claimed in claim 1 comprising doped titanium dioxide.

5. The photocatalyst as claimed in claim 4 wherein the dopant is selected from any one or more of the group comprising:

fluorine, iron, nitrogen, phosphorus, and sulphur.

6. The photocatalyst as claimed in claim 5 wherein the dopant is nitrogen.

7. The photocatalyst as claimed in claim 4 wherein the dopant comprises between about 1:

0.0001 and about 1;

0.5 molar ratio titanium dioxide;

dopant.

8. The photocatalyst as claimed in claim 4 wherein the dopant comprises between about 1:

0.05 to about 1;

0.25 molar ration titanium dioxide;

dopant.

9. The photocatalyst as claimed in claim 1 wherein the photocatalyst has a crystalline structure.

10. The photocatalyst as claimed in claim 9 wherein the photocatalyst has a crystallite size range of between about 5 nm to about 50 nm.

11. The photocatalyst as claimed in claim 9 wherein the photocatalyst has a crystalline size range of between about 10 nm to about 30 nm.

12. An antimicrobial composition comprising a photocatalyst as claimed in claim 1.

13. A film or coating comprising a photocatalyst as claimed in claim 1.

14. An antimicrobial film or coating comprising the photocatalyst as claimed in claim 1.

15. The photocatalyst as claimed in claim 1 wherein the photocatalyst has a band gap width of 2.82 eV or less.

16. A photocatalyst comprising undoped mesoporous titanium dioxide with a band gap width of 2.9 eV and a surface area of between 100 m²/g and 400 m²/g.

17. A process for forming a nanoporous crystalline material from an inorganic or organic precursor thereof comprising the steps of:

i) preparing a suspension from the inorganic or organic precursor; and

ii) utilising microwave irradiation, under non-pressurised conditions suitable to crystallise the material from the suspension, to crystallise the material from the suspension;

wherein the process takes place at a temperature of about 100°

C.

18. A process for the formation of a nanoporous crystalline material with a low energy band gap comprising the step of utilising microwave irradiation under non-pressurised conditions to crystallise a suspension of an inorganic or organic precursor of a nanoporous crystalline material under suitable conditions to form a nanoporous crystalline material with a low energy band gap, wherein the process takes place at a temperature of about 100°

C.