Tech Briefs

Use of Selective Oxidation Catalyst for Amperometric Sensing Electrode

Lyndon B. Johnson Space Center, Houston, Texas

A modified oxidation catalyst material can be used to build a carbon-monoxide-sensing electrode for amperometric sensors to overcome the typical cross-sensitivity of these sensors toward hydrogen. The technology will have applications in the emerging hydrogen fuel cell economy for monitoring traces of carbon monoxide in the fuel feed of hydrogen fuel cells.

Amperometric electrochemical sensors are a class of toxic gas sensors in which an electrochemical cell comprising an electrolyte solution and two or three electrodes is used to oxidize or reduce a target analyte. The resulting electrical current is a measure of the quantity of analyte being discharged. The quantity of analyte transported to the electrode is limited by a diffusion, or permeation, membrane so that the analyte flux to the electrode, and thus the electric current, is proportional to the analyte concentration in the air. A potentiostat circuit is used to poise the electrode potential at a level chosen to maximize selectivity for the target analyte. Nevertheless, cross-sensitivity toward non-target analytes is a chronic problem for these sensors.

This approach involves using an alternative catalytic material in the construction of the electrode. This disclosed design is suggesting that the manufacture of an electrochemical sensing electrode from a selective oxidation catalyst may result in a sensor with very high selectivity toward CO.

This work was done by Kenneth Carney of Hamilton Sunstrand Space Systems International for Johnson Space Center. For further information, contact the JSC Innovation Partnerships Office at (281) 483-3809.

Title to this invention has been waived under the provisions of the National Aeronautics and Space Act {42 U.S.C. 2457(f)} to Hamilton Sundstrand Space Systems International. Inquiries concerning licenses for its commercial development should be addressed to:

Hamilton Sundstrand Space Systems International
2771 North Garey Ave.
Pomona, CA 91767-1809
Phone No.: (909) 593 3581

Refer to MSC-24877-1.