Towards fluoride-based oxygen gas sensors operating at room temperature: Effects of the whisker materials incorporated in the sensing electrode on response time

This study is concerned with improvement of the response time of the amperometric oxygen sensors of the type, Ag\Ag6I4WO\PbSnF(4)sensing electrode, O-2, of which sensing electrode was a mixture of iron(II) phthalocyanine, PbSnF4 and a whisker material (one of 9Al(2)O(3) . 2B(2)O(3) and TiO2 whiskers different in length, aspect ratio and conductivity). A good linear relation was found between the short-circuit-current and the square root of oxygen partial pressure for all the sensing electrode mixtures. The response time was strongly influenced by the length and conductivity of the incorporated whisker materials. Incorporation of an whisker material with appropriate length (similar to 20 mu m), conductivity (similar to 10(-1) S cm(-1)) and aspect ratio (20) was found to allow fast response (20 s) at room temperature. The fast response results from formation of uniform reduction sites on the conductive whisker network in the sensing electrode.