Impedancemetric Technique for NOx Sensing Using a YSZ-Based Electrochemical Cell
An impedancemetric technique for NO{sub x} sensing using a yttria-stabilized zirconia (YSZ) electrochemical cell is reported. The cell consists of a dense YSZ substrate disk with two YSZ/metal-oxide electrodes deposited on the same side. The cell is completely exposed to the test gas (no air reference). The NO{sub x} and O{sub 2} response of the cell were evaluated during constant-frequency operation at frequencies in the range from 1 to 1000 Hz. At 10 Hz, the NO{sub x} response (as measured by phase angle shift) is shown to be linear with concentration over the range from 8-50 ppm, with comparable response to both NO and NO{sub 2}. A method of operation is described which enables compensation for the O{sub 2} response at oxygen concentrations greater than approximately 4%. This mode of operation allows the sensor to provide sub-10 ppm detection of NO{sub x} irrespective of the O{sub 2} concentration. The sensor exhibits good stability during continuous operation for more than 150 hr. It was observed that the O{sub 2} response of the cell is too slow to be of practical use, taking several minutes to equilibrate after changing the concentration by a few percent. However, data will be presented which demonstrate that this response is related to the metal oxide used for the electrode; and more rapid response times can be achieved by modification of the electrode material.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 896579
- Report Number(s):
- UCRL-CONF-222247; TRN: US200703%%833
- Resource Relation:
- Journal Volume: 972; Conference: Presented at: Materials Research Society Meeting, Boston, MA, United States, Nov 27 - Dec 01, 2006
- Country of Publication:
- United States
- Language:
- English
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