P2.7.7 Detection of Reducing Gases in Air: Experiment and Theory

14th International Meeting on Chemical Sensors - IMCS 2012
2012-05-20 - 2012-05-23
Nürnberg/Nuremberg, Germany
P2.7 Nanostructured Metal Oxide-based Sensors
L. Trakhtenberg, G. Gerasimov, T. Belysheva, M. Kozhushner, V. Gromov - Semenov Institute of Chemical Physics RAS (Russia), O. Ilegbusi - University of Central Florida (USA)
1619 - 1622


The sensor responses (com) of SnO2 + In2O3 and ZnO + In2O3 nanocomposite films to H2 and CO in air are investigated for varying oxide compositions. Sensor properties of the In2O3 + SnO2 composite are determined by the interaction between components, which leads to the transfer of electrons from In2O3 to SnO2. The degree of electron transfer increases under the action of reducing gases that is the cause of an increase in com when added In2O3 to SnO2. Moreover SnO2 acts as a catalyst of H2-dissociation and the H-atoms formed on the surface of SnO2 react with more reactive O- on the In2O3 surface. This creates especially favorable conditions for hydrogen detection and the response of the composite sensor to hydrogen is higher than the response of pure SnO2 and In2O3. Small additions of ZnO (up to 3-5 wt%) alter the electronic structure of In2O3 and leads to the same increase in ?com both to H2 and CO. When further raised of ZnO content to 20 wt%, com to H2 is increased approximately 200%, whereas response to CO varies very slightly. As SnO2, ZnO effectively catalyzes the hydrogen dissociation and in contact with In2O3 it leads to chemical sensitization com to H2. A new model of sensor phenomena has been developed.