11 October 2007 Hunting the active species in gas sensing processes: operando studies on tin dioxide-based sensors
Author Affiliations +
Abstract
The understanding of the gas sensing mechanism at a fundamental level implies the knowledge of the state of preadsorbed surface species. Some question marks on the commonly accepted ideas were raised by the recorded higher sensitivity of sensors to CO in nitrogen and by the fact that the combustion of CO was observed in air and in humid nitrogen. These facts question the monopoly of oxygen ions as the reaction partners for CO and they were the driving force for thereby presented investigations. DRIFT Spectroscopy and resistance measurements have been simultaneously applied to discriminate between the species that are actively taking part in the sensing processes and spectators. The comparison between the different sensors has been focused on verifying whether the observed phenomena are general or whether they depend on the technology. It was observed that for SnO2 sensors, the reaction of oxygen, with water results in the formation of terminal hydroxyls and the release of an electron to the conduction band. It indicates that water compete with reducing gases for the oxygen ions. This phenomenon was independent of the technology and thus it could be SnO2 characteristic. It was shown that CO reacts preferentially with ionosorbed oxygen at the surface of tin dioxide. In the case of lack of oxygen different scenarios are possibly dependent on hydration state of the surface.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
D. Koziej, N. Barsan, U. Weimar, "Hunting the active species in gas sensing processes: operando studies on tin dioxide-based sensors", Proc. SPIE 6769, Nanosensing: Materials, Devices, and Systems III, 676906 (11 October 2007); doi: 10.1117/12.731222; https://doi.org/10.1117/12.731222
PROCEEDINGS
10 PAGES


SHARE
RELATED CONTENT

H2O D2O exchange in the presence of CO over SnO2...
Proceedings of SPIE (September 16 2013)
MEMS device for mass market gas and chemical sensors
Proceedings of SPIE (August 15 2000)
Sensors in air and gas monitoring
Proceedings of SPIE (July 22 2002)
Chemical gas sensors on silicon
Proceedings of SPIE (September 15 1995)

Back to Top