Gas sensor element and methods of making and using the same

• US 20070125664A1
• Filed: 12/05/2005
• Published: 06/07/2007
• Est. Priority Date: 12/05/2005
• Status: Abandoned Application

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Kupe, Joachim, Symons, Walter, LaBarge, William
• Application Number:
  US11/295,030
• Publication Number:
  US 20070125664A1
• Time in Patent Office: Days
• US Class Current: 205/780.500
• CPC Class Codes: G01N 27/4071 using sensor elements of laminated structure

Abstract

In one embodiment, a gas sensor element comprises: an electrolyte disposed between and in ionic communication with a first electrode and a second electrode; and a protective layer disposed adjacent to the first electrode. The protective layer comprises a catalytic coating comprising a reducible support material, a catalyst, and a water activator material. The catalyst coating is capable of converting an oxygen consuming species in a gas to an oxygen donating species.

Claims

1. A gas sensor element, comprising:

an electrolyte disposed between and in ionic communication with a first electrode and a second electrode; and

a protective layer disposed adjacent to the first electrode, wherein the protective layer comprises a catalytic coating comprising a reducible support material, a catalyst, and a water activator material;

wherein the catalyst coating is capable of converting an oxygen consuming species in a gas to an oxygen donating species.

2. The gas sensor element of claim 1, wherein the oxygen consuming species is selected from the group consisting of ammonia, nitrogen oxide, nitrous oxide, carbon monoxide, and combinations comprising at least one of the foregoing.

3. The gas sensor element of claim 2, wherein the oxygen donating species is selected from the group consisting of nitrogen dioxide, carbon dioxide, and combinations comprising at least one of the foregoing.

4. The gas sensor element of claim 2, wherein the oxygen consuming species is selected from the group consisting of nitrogen oxide, nitrous oxide, and combinations comprising at least one of the foregoing.

5. The gas sensor element of claim 1, wherein the reducible support material comprises a nanocrystalline material.

6. The gas sensor element of claim 5, wherein the reducible support material is selected from the group consisting of titanium suboxides, gallium suboxides, tin suboxides, silicon suboxides, and combinations comprising at least one of the foregoing.

7. The gas sensor element of claim 5, wherein the reducible support material comprises a titanium suboxide selected from the group consisting of Ti₄O₇, Ti₃O₅, Ti₂O₃, TiO, and combinations comprising at least one of the foregoing.

8. The gas sensor element of claim 1, wherein the catalyst has a particle size, measured along a major axis, of less than or equal to about 25 nm.

9. The gas sensor element of claim 8, wherein the particle size is about 0.1 to about 10 mn.

10. The gas sensor element of claim 9, wherein the particle size is about 2 nm to about 5 nm.

11. The gas sensor element of claim 1, wherein the water activator material can be in the form of a layer on the catalyst having a thickness of less than or equal to about 10 nm.

12. The gas sensor element of claim 1, wherein the water activator material comprises a zirconium compound.

13. The gas sensor element of claim 12, wherein the zirconium compound is selected from the group consisting of zirconium ethoxide, zirconium oxychloride, zirconium tert-butoxide, zirconium isopropoxide, colloidal zirconium oxide, zirconium dioxide, as well as combinations comprising at least one of the foregoing.

14. The gas sensor element of claim 1, wherein the water activator material is present in the coating in an amount of about 0.5 wt. % to about 2 wt % , based upon a total weight of the coating.

15. The gas sensor element of claim 1, wherein the catalytic coating has a porosity of about 5 vol % to about 15 vol %, based upon a total volume of the catalyst coating.

16. The gas sensor of claim 15, wherein pores in the catalytic coating have an average size, measured along a major axis, of about 0.01 nm to about 10 nm.

17. The gas sensor element of claim 1, wherein the catalytic coating has a thickness of less than or equal to about 200 μ

m.

18. The gas sensor element of claim 1, wherein the a reducible support material comprises a titanium suboxide, the catalyst comprises gold, and the water activator material comprises a zirconium oxide.

19. A method of sensing NOx in a gas stream, comprising:

contacting a gas sensor element with the gas stream, wherein the gas sensor element comprises

an electrolyte disposed between and in ionic communication with a first electrode and a second electrode; and

a protective layer disposed adjacent to the first electrode, wherein the protective layer comprises a catalytic coating comprising a reducible support material, a catalyst, and a water activator material;

converting oxygen consuming species in the gas to oxygen donating species to form a converted gas;

contacting the first electrode with the converted gas; and

measuring a concentration of NOx in the gas stream.

20. The method of claim 19, wherein the a reducible support material comprises a titanium suboxide, the catalyst comprises gold, and the water activator material comprises a zirconium oxide.