SENSITIVE LAYER FOR ELECTROCHEMICAL DETECTION OF HYDROGEN-CYANIDE

Electrochemically polymerized polyaniline with metal clusters incorporated into the bulk of the film serves as a sensing layer for gaseous HCN in the concentration range 0.13-20 ppm. The interaction of the gas with this layer causes a reversible and reproducible change of its work function which is measured with a Kelvin probe. The response is logarithmic, suggesting a bulk mechanism. The slope of the concentration dependence is between 20 and 35 mV/decade of HCN. The major factor affecting the sensitivity is the total thickness of the layer and the thickness of the space charge inside the layer. The optimum performance was obtained from the films utilizing the polyaniline/Hg/phosphate system.