Results on light-enhanced NO2 sensing utilizing ordered mesoporous In2O3 are presented and interpreted by means of a new sensing model for ordered mesoporous indium oxide (In2O3). This model aims to explain the drop in electronic resistance of n-type semiconducting In2O3 under UV light exposure as well as the light-enhanced sensing properties to oxidizing gases. Compared to the conventional double Schottky model the dominating factor for the resistance change is a change of oxygen vacancy donor states in the bulk phase due to photoreduction. Comparison of conductivity measurements with varying oxygen partial pressure for ordered mesoporous and non-structured material shows an accumulative behavior in the case of the mesoporous material which can be related to faster photo reduction caused by the nanostructure. IR measurements reveal a donor level of 0.18 eV below the conduction band attributed to oxygen vacancies. The unique properties resulting from the structure allow low-temperature sensing of NO2; especially the recovery times are significantly shorter for the mesoporous material.
Mechanistic Model for UV light-enhanced NO2 Sensing utilizing Ordered Mesoporous In2O3
MALAGU', Cesare;
2012
Abstract
Results on light-enhanced NO2 sensing utilizing ordered mesoporous In2O3 are presented and interpreted by means of a new sensing model for ordered mesoporous indium oxide (In2O3). This model aims to explain the drop in electronic resistance of n-type semiconducting In2O3 under UV light exposure as well as the light-enhanced sensing properties to oxidizing gases. Compared to the conventional double Schottky model the dominating factor for the resistance change is a change of oxygen vacancy donor states in the bulk phase due to photoreduction. Comparison of conductivity measurements with varying oxygen partial pressure for ordered mesoporous and non-structured material shows an accumulative behavior in the case of the mesoporous material which can be related to faster photo reduction caused by the nanostructure. IR measurements reveal a donor level of 0.18 eV below the conduction band attributed to oxygen vacancies. The unique properties resulting from the structure allow low-temperature sensing of NO2; especially the recovery times are significantly shorter for the mesoporous material.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
