Use of solid state protonic conductors for oxygen potentiometric sensor at room temperature

Abstract

The use of oxygen sensors based on oxygen conductors such as stabilized zirconia is restricted at temperatures 300°C. Oxygen sensors operating at room temperature are however required for many purposes, especially in environmental and biological analyses. We have therefore studied the realization of a simple solid state sensor for oxygen at room temperature, which utilizes a thin film of pellicular zirconium phosphate or NAFION as protonic conductor, a titanium hydride plate as solid state reference electrode and a sensing catalytic electrode of Pt. Such a sensor is based on the H 2-O 2 mixed potential which is produced at the sensing electrode when short pulses of current are applied. Potential measurements are periodically performed after a suitable delay time forms the end of each pulse. The potential is a linear function over a large range of log P o 2 , while, in the most favourable conditions, the sensitivity limit is of a few parts per millions.