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Issue 38, 2012
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An Au clusters related spill-over sensitization mechanism in SnO2-based gas sensors identified by operando HERFD-XAS, work function changes, DC resistance and catalytic conversion studies

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Abstract

The role of Au additives in SnO2-based thick film gas sensors was investigated by a combination of operando investigation techniques, namely spectroscopic high energy resolved fluorescence detected X-ray absorption spectroscopy (HERFD-XAS) and simultaneous DC resistance and work function change measurements. The results have shown that the Au is present in the form of small metallic particles at the surface of the host metal oxide without changing its bulk or surface electronic properties. The sensitization effect of Au can therefore be attributed to the “spill-over effect”, meaning that the Au particles enrich the surface of the active metal oxide with oxygen species which consequently react with reducing gases such as CO and H2. This is in contrast to the effect of Pd and Pt promoters which were found to be distributed at an atomic level on the surface and in the bulk of the supporting sensing material and therefore have a tremendous effect on its bulk and surface electronic properties.

Graphical abstract: An Au clusters related spill-over sensitization mechanism in SnO2-based gas sensors identified by operando HERFD-XAS, work function changes, DC resistance and catalytic conversion studies

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Article information


Submitted
27 Apr 2012
Accepted
08 Aug 2012
First published
08 Aug 2012

Phys. Chem. Chem. Phys., 2012,14, 13249-13254
Article type
Paper

An Au clusters related spill-over sensitization mechanism in SnO2-based gas sensors identified by operando HERFD-XAS, work function changes, DC resistance and catalytic conversion studies

M. Hübner, D. Koziej, J. Grunwaldt, U. Weimar and N. Barsan, Phys. Chem. Chem. Phys., 2012, 14, 13249
DOI: 10.1039/C2CP41349C

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