THE MECHANISM OF OPERATION OF TIN(IV) OXIDE CARBON-MONOXIDE SENSORS

The electrical properties of tin(IV) oxide render it an excellent material for the detection of very low levels of carbon monoxide. In this paper, the authors describe experiments in which the nature of the surface species adsorbed into tin(IV) oxide from atmospheres containing low levels of carbon monoxide is monitored using transmission infrared spectroscopy while simultaneously measuring the electrical changes produced in the bulk oxide. The data demonstrate the effect of heat treatment on the formation of adsorbate species and the mutual interdependence of adsorbate species and bulk oxide electrical conductance. This relationship is important both for sensor operation and heterogeneous catalysis.