Carbon Monoxide and Hydrogen Detection by Anatase Modification of Titanium Dioxide

Abstract

From the viewpoint of industrial and automobile exhaust pollution control, a sensor capable of detecting and measuring the concentration of harmful gases such as carbon monoxide and hydrogen in the ambient is desired. This paper describes the development and use of a titania (TiO 2 )‐based semiconducting oxide material as a reliable and rugged CO and H 2 gas sensor in the temperature range of 773 to 1073 K. Significant change in the sensing characteristic of the anatase modification of TiO 2 was observed when admixed with an insulating second phase, such as alumina or yttria. In the case of TiO 2 –10 wt% Al 2 O 3 , the sensor response was found to be exclusively dependent on the hydrogen concentration alone; the presence of CO or CO 2 did not affect the sensitivity. On the other hand, the sensor based on TiO 2 –10 wt% Y 2 O 3 showed increased sensitivity to CO and decreased sensitivity to H 2 , compared to that of the undoped TiO 2 . Addition of elemental iron, in small concentration, to the two‐phase mixture of titania and yttria seemed to further improve the sensitivity and selectivity of the latter to CO.