Mechanism of sensitivity promotion in CO sensor using indium oxide and cobalt oxide

The sensitivity, as well as selectivity of an In2O3-based element to CO over H2, was improved dramatically by the addition of 0.5 wt.% cobalt oxide and 0.04 wt.% Au. The doubly promoted element thus obtained gave excellent CO-sensing characteristics at 250°C. It was suggested from the measurements of catalytic oxidation activities of the In2O3-based materials that the remarkable promotion of CO-sensing properties originated from the proper enhancement of CO oxidation activity.