Operando Investigations of Differently Prepared In 2 O 3 - Gas Sensors

In this study, the electrical characteristics and surface reactions of three different kinds of In2O3 based gas sensors were investigated under CO exposure in dry and humid air by using DC electrical resistance measurements and Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). For the first time one gains insight into the surface reactions during the exposure to CO and humidity. The sensors show different behavior on the baseline in humidity depending on the material which is due to different kinds of OH-groups. The resistance change under CO and humidity exposure are additive and the molecules compete for the same reaction partner confirmed by the spectroscopy results. Through isotopic exchange experiments, different adsorbates could be identified.