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An amperometric solid‐state sensor for Nitrogen dioxide based on a solid polymer electrolyte
Author(s) -
Opekar František
Publication year - 1992
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140040202
Subject(s) - nitrogen dioxide , amperometry , solid state , electrolyte , polymer , polymer electrolytes , materials science , inorganic chemistry , chemistry , chemical engineering , electrode , electrochemistry , organic chemistry , ionic conductivity , engineering
A new sensor is described consisting of a Nafion membrane to which a very fine gold square grid indicator electrode is mechanically pressed. A platinum counter and a Pt/air reference electrode are prepared on the membrane using a chemical plating method. Nitrogen dioxide was determined in air by reduction at −0.3V vs. Pt/air electrode (0.75 V vs. SHE). The response dependence on the NO 2 concentration was linear, with a sensitivity of 59 nA.ppm −1 (42% rel. humidity). The time constant and the time required to attain 95% of the steady ‐state response were 2.2 and 10 s, respectively. The response was independent of the air flow rate, but increased linearly with increasing relative humidity. The sensor sensitivity decreased with time–the longer the sensor was in contact with NO 2 . The decrease amounted to ca. 5% per 24 hours during constant exposure to NO 2 . The indicator electrode can be reactivated by cyclic polarization. On the basis of the sensitivity attained, the indicator electrode can be considered as an array of microband electrodes.