Photo electrodes

• US 8,673,810 B2
• Filed: 11/14/2008
• Issued: 03/18/2014
• Est. Priority Date: 11/16/2007
• Status: Active Grant

• Current Assignee: 579453 Ontario Incorporated
• Original Assignee: Aqua Diagnostic Pty., Ltd.
• Inventors: Zhao, Huijun, Imisides, Mark, Zhang, Shanqing
• Primary Examiner(s): Olsen, Kaj K
• Assistant Examiner(s): DARJI, PRITESH D
• Application Number:
  US12/743,078
• Publication Number:
  US 20120010068A1
• Time in Patent Office: 1,950 Days
• Field of Search: 516/90, 502/350, 423/610
• US Class Current: 502/350
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 37/0018 Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
• CPC Class Codes: B01J 37/10 in the presence of water, e.g. steam
• 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 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2004/04 obtained by TEM, STEM, STM or AFM
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C03C 17/3417 all coatings being oxide coatings
• CPC Class Codes: C03C 2217/71 Photocatalytic coatings
• CPC Class Codes: C03C 2217/948 Layers comprising indium tin oxide [ITO]
• CPC Class Codes: C03C 2218/11 from solutions or suspensions
• CPC Class Codes: C03C 2218/32 After-treatment
• 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

Abstract

Methods of fabricating nano particulate Titanium dioxide photocatalysts onto a conducting substrate are disclosed. The methods include hydrothermal fabrications with heat treatment steps to increase the crystallinity and photoactivity of the titanium dioxide layers.

Claims

1. A method of forming a titanium dioxide thin film photocatalyst in which,

a) titanium dioxide colloidal particles are formed in solution and then subjected to dialysis while maintaining the pH below 4,

b) the dialysed solution is then subjected to a hydrothermal treatment,

c) the colloid from step b) is then coated on a substrate of conducting glass and dried, and

d) the coated substrate from step c) is calcined from 700 C to 800 C to produce a titanium dioxide layer which contains from 0.1% to 3.5% rutile and the balance anatase.

2. A method of forming a titanium dioxide photocatalyst as claimed in claim 1 in which the colloid from step b) has an average particle size in the range of 8 to 35 nm.

3. A method as claimed in claim 1 in which the dialysis is concluded at a pH of about 3.8 and the calcination is at about 700 C for about two hours.

4. A method of forming a titanium dioxide photocatalyst as claimed in claim 1 which the substrate is conducting glass which is sequentially washed with detergent, chromic acid and alcohol.

5. A method as claimed in claim 4 in which the titanium dioxide layer has a thickness of from 0.5 to 20 microns.

6. A method as claimed in claim 1, in which step c) is repeated before proceeding to step d).

7. A method as claimed in claim 1, in which the colloidal particles are filtered prior to the dialysis treatment.