A new potentiometric NO sensor based on a NO+ cation conducting ceramic membrane

A potentiometric NO sensor principle based on NO+ cation conducting β″-alumina is presented. Main part of the sensor is a nitrosyl (NO+) cation conducting membrane generating a potential difference between two different NO partial pressures by the reaction NO↔NO++e−. If the membrane is situated as a separator between a reference gas and a measuring gas, a Nernstian behavior with a slope close to n=1 in a semi-logarithmic plot (n is the number of electrons involved in the reaction) can be found. The Nernstian behavior was verified in a NO partial pressure range of 10–1000 Pa (100–10,000 ppm NO) with several reference partial pressures. The cross sensitivity to oxygen, water, carbon monoxide and carbon dioxide was determined and found, with the exception of oxygen, to be as low as expected from a NO+ selective ion conducting membrane.