Carbon monoxide sensor having mercury doped electrodes

• US 5,635,627 A
• Filed: 05/25/1995
• Issued: 06/03/1997
• Est. Priority Date: 05/26/1994
• Status: Expired due to Fees

• Current Assignee: Endress+Hauser GmbH+Co (ENDRESS)
• Original Assignee: Endress+Hauser GmbH+Co (ENDRESS)
• Inventors: Bytyn, Wilfried
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): LARKIN, DANIEL SEAN
• Application Number:
  US08/450,278
• Time in Patent Office: 740 Days
• Field of Search: 73/23.2, 73/23.31, 73/31.01, 73/31.05, 73/31.07, 204/412, 204/415, 204/431, 204/432
• US Class Current: 73/31.05
• CPC Class Codes: G01N 27/4045 for gases other than oxygen
• CPC Class Codes: G01N 33/004 CO or CO2

Abstract

In this carbon monoxide sensor, particularly for measuring carbon monoxide in flue gases, which must be operated in a controlled-potential bias circuit and which comprises a working electrode, a counter electrode, and a reference electrode, all of platinum black, as well as an electrolyte connected with these three electrodes, the hydrogen cross-sensitivity is drastically reduced by providing two layers enriched by mercury and/or mercury ions, one on a surface of the working electrode and one of a surface of the reference electrode. These two electrodes are treated with mercury or a mercury compound before or after incorporation into the sensor.

Claims

1. A carbon monoxide sensor, for measuring carbon monoxide in flue gases, the carbon monoxide sensor comprising:

a working electrode of platinum black;

a counter electrode of platinum black;

a reference electrode of platinum black;

each of the working electrode, and reference electrode including a carbon monoxide contacting surface;

an electrolyte connected with the working electrode, the counter electrode and the reference electrode; and

two layers enriched by mercury and/or mercury ions, one on the carbon monoxide contacting surface of the working electrode and one on the carbon monoxide contacting surface of the reference electrode.

2. A carbon monoxide sensor as claimed in claim 1 wherein each of the layers enriched by mercury and/or mercury ions is few atomic layers thick.

3. A method of manufacturing a carbon monoxide sensor, for measuring carbon monoxide in flue gases, the carbon monoxide sensor comprising

a working electrode of platinum black;

a counter electrode of platinum black;

a reference electrode of platinum black;

each of the working electrode, counter electrode and reference electrode including a carbon monoxide contacting surface, and

an electrolyte connected with the working electrode, the counter electrode, and the reference electrode;

said method comprising the step of treating the carbon monoxide contacting surfaces of the working electrode and the reference electrode with mercury or a mercury compound.

4. A method as claimed in claim 3 wherein the surfaces treated with mercury or a mercury compound are reduced for amalgamation.

5. The method as claimed in claim 3 wherein at least one of the working electrode and reference electrode are treated with mercury or a mercury compound before incorporation into the carbon monoxide sensor.

6. The method as claimed in claim 3 wherein at least one of the working electrode and reference electrode are treated with mercury or a mercury compound after incorporation into the carbon monoxide sensor.