New Sensing Model of (Mesoporous) In2O3

Recently indium oxide (In2O3) attracted attention as a material for sensing layers in semiconducting gas sensors. Compared to frequently investigated materials like tin dioxide (SnO2), tungsten trioxide (WO3), or gallium oxide (Ga2O3) indium oxide offers some unique properties. The most prominent one is its selectivity to oxidizing gases such as ozone (O3) or nitrogen dioxide (NO2)at low operating temperatures (<150C). Combined with the photoreduction properties of nanocast, porousIn2O3highly selective sensing layers with a fast response can be prepared. In some cases even room temperature measurements are possible; therefore this material allows for designing low-power sensors without the need for special sensor substrates (e.g.,μ-hotplates). Detailed analysis of the sensing mechanism reveals that known sensing models are not able to describe the observed effects. Therefore a new sensing model for ordered nanoporous In2O3is presented which will be applicable for nonstructured material too.