Nucleation layers for enhancing photocatalytic activity of titanium dioxide (TiO2) coatings

• US 10,195,602 B2
• Filed: 12/01/2016
• Issued: 02/05/2019
• Est. Priority Date: 12/01/2016
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Dadheech, Gayatri Vyas, Seder, Thomas A., Carpenter, James A.
• Primary Examiner(s): Nguyen, Cam N.
• Application Number:
  US15/366,991
• Publication Number:
  US 20180154345A1
• Time in Patent Office: 796 Days
• CPC Class Codes: B01J 21/04 Alumina
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 35/40 characterised by dimensions, e.g. grain size in a colloidal state B01J35/23; crystallite size B01J35/77
• CPC Class Codes: B01J 37/349 making use of flames, plasmas or lasers
• CPC Class Codes: C07D 279/20 with hydrogen atoms directly attached to the ring nitrogen atom

Abstract

A photocatalytic system having enhanced photo efficiency/photonic efficacy is provided that includes a thin nucleation material coated on a substrate. The nucleation material enhances lattice matching for a subsequently deposited photocatalytic active material. Such a photocatalytic system may be used as a self-cleaning surface in an application where removal of fingerprints and other residue is desired. In certain aspects, the nucleation material comprises aluminum oxide (Al₂O₃) and the photocatalytic material comprises an anatase phase of titanium dioxide (TiO₂) deposited over the nucleation material. A photocatalytic activity of the system is ≥ about 50% above a comparative photocatalytic activity where the photocatalytic active material is disposed directly on the substrate. Methods of making such photocatalytic systems are also provided.

Claims

1. A photocatalytic system comprising:

a nucleation material coated on a substrate, wherein the nucleation material comprises a metal oxide compound, wherein the metal is selected from the group consisting of;

aluminum, zirconium, niobium, cerium, vanadium, lanthanum, titanium, silicon, iron, cobalt, nickel, molybdenum, tungsten, and combinations thereof, and wherein the nucleation material has an average thickness of less than or equal to about 10 nm; and

a photocatalytic active material comprising an anatase phase of titanium dioxide (TiO₂) deposited over the nucleation material, wherein a photocatalytic activity is greater than or equal to about 50% above a comparative photocatalytic activity where the photocatalytic active material is disposed directly on the substrate.

2. The photocatalytic system of claim 1, wherein the nucleation material is selected from the group consisting of:

aluminum oxide (Al₂O₃), SrTiO₃ (STO), LaAlO₃ (LAO), Y stabilized ZrO₂ (YSZ), and combinations thereof.

3. The photocatalytic system of claim 1, wherein the nucleation material comprises aluminum oxide (Al₂O₃).

4. The photocatalytic system of claim 3, wherein the aluminum oxide (Al₂O₃) comprises a θ

-Al₂O₃ phase having a monoclinic space group with lattice parameters of a=1.185 nm, b=0.295 nm and c=0.562 nm.

5. The photocatalytic system of claim 1, wherein a lattice mismatch is less than or equal to about 12% between the nucleation material and the photocatalytic active material.

6. The photocatalytic system of claim 1, wherein the active material comprises greater than or equal to about 50% by volume of anatase phase.

7. The photocatalytic system of claim 1, wherein the photocatalytic activity is greater than or equal to about 75% above the comparative photocatalytic activity where the active material is disposed directly on the substrate.

8. A self-cleaning photocatalytic system comprising:

a substrate;

a nucleation coating comprising aluminum oxide (Al₂O₃) disposed on the substrate having a thickness of less than or equal to about 10 nm; and

an exposed surface comprising a photocatalytic active material that comprises an anatase phase of titanium dioxide (TiO₂) deposited over the nucleation coating, wherein the photocatalytic active material facilitates a decomposition reaction of any oil or organic residue on the exposed surface when in the presence of water and ultraviolet radiation.

9. The self-cleaning photocatalytic system of claim 8, wherein a photocatalytic activity of the self-cleaning photocatalytic system is greater than or equal to about 50% above a comparative photocatalytic activity where the photocatalytic active material is disposed directly on the substrate.

10. The self-cleaning photocatalytic system of claim 8, wherein the nucleation coating has an average thickness of greater than or equal to about 3 nm to less than or equal to about 5 nm.

11. The self-cleaning photocatalytic system of claim 8, wherein the photocatalytic active material comprises greater than or equal to about 50% by volume of the anatase phase of titanium dioxide (TiO₂).

12. The self-cleaning photocatalytic system of claim 8, wherein the substrate comprises glass or an anti-reflection coating.

13. The self-cleaning photocatalytic system of claim 8, wherein the exposed surface defines a plurality of islands of the photocatalytic active material distributed within a low surface energy polymeric material, wherein the nucleation coating is disposed beneath the photocatalytic active material, but is absent in regions where the low surface energy polymeric material is present.

14. The self-cleaning photocatalytic system of claim 8, wherein a lattice mismatch is less than or equal to about 2% between the nucleation coating and the photocatalytic active material.

15. The self-cleaning photocatalytic system of claim 8, wherein the aluminum oxide (Al₂O₃) comprises a θ

-Al₂O₃ phase having a crystal structure having a monoclinic space group with lattice parameters of a=1.185 nm, b=0.295 nm and c=0.562 nm that enhances lattice matching and formation of the anatase phase of titanium dioxide (TiO₂).

16. A method of enhancing photocatalytic activity in a photocatalytic system comprising:

depositing a nucleation material coated on a substrate, wherein the nucleation material comprises a metal oxide compound, wherein the metal is selected from the group consisting of aluminum, zirconium, niobium, cerium, vanadium, lanthanum, titanium, silicon, iron, cobalt, nickel, molybdenum, tungsten, and combinations thereof, and wherein the nucleation material has an average thickness of less than or equal to about 10 nm; and

depositing a photocatalytic active material comprising an anatase phase of titanium dioxide (TiO₂) over the nucleation material, wherein the nucleation material provides lattice matching to enhance formation of the anatase phase of titanium dioxide (TiO₂), so that a photocatalytic activity is greater than or equal to about 50% above a comparative photocatalytic activity where the photocatalytic active material is disposed directly on the substrate.

17. The method of claim 16, wherein the depositing of the nucleation material is a process selected from the group consisting of:

atomic layer deposition (ALD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (CVD), physical vapor deposition (PVD), and combinations thereof.

18. The method of claim 16, wherein the depositing of the photocatalytic active material is a process selected from the group consisting of:

atomic layer deposition (ALD), chemical vapor deposition (CVD), atmospheric pressure chemical vapor deposition (APCVD), low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (CVD), physical vapor deposition (PVD), magnetron sputtering, wet chemistry, sol-gel processes, and combinations thereof.

19. The method of claim 16, wherein the depositing of the nucleation material is done by an atomic layer deposition process.