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Rhodium oxide surface-loaded gas sensors

Staerz, A.; Boehme, I.; Degler, D.; Bahri, M.; Doronkin, D. E. ORCID iD icon 1,2; Zimina, A. 1,2; Brinkmann, H.; Herrmann, S.; Junker, B.; Ersen, O.; Grunwaldt, J.-D. ORCID iD icon 1,2; Weimar, U.; Barsan, N.
1 Institut für Katalyseforschung und -technologie (IKFT), Karlsruher Institut für Technologie (KIT)
2 Institut für Technische Chemie und Polymerchemie (ITCP), Karlsruher Institut für Technologie (KIT)


In order to increase their stability and tune-sensing characteristics, metal oxides are often surface-loaded with noble metals. Although a great deal of empirical work shows that surface-loading with noble metals drastically changes sensing characteristics, little information exists on the mechanism. Here, a systematic study of sensors based on rhodium-loaded WO₃, SnO₂, and In₂O₃—examined using X-ray diffraction, high-resolution scanning transmission electron microscopy, direct current (DC) resistance measurements, operando diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and operando X-ray absorption spectroscopy—is presented. Under normal sensing conditions, the rhodium clusters were oxidized. Significant evidence is provided that, in this case, the sensing is dominated by a Fermi-level pinning mechanism, i.e., the reaction with the target gas takes place on the noble-metal cluster, changing its oxidation state. As a result, the heterojunction between the oxidized rhodium clusters and the base metal oxide was altered and a change in the resistance was detected. Through measurements done in low-oxygen background, it was possible to induce a mechanism switch by reducing the clusters to their metallic state. ... mehr

Verlagsausgabe §
DOI: 10.5445/IR/1000087873
Veröffentlicht am 03.12.2018
DOI: 10.3390/nano8110892
Zitationen: 22
Web of Science
Zitationen: 21
Zitationen: 23
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Katalyseforschung und -technologie (IKFT)
Institut für Technische Chemie und Polymerchemie (ITCP)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2018
Sprache Englisch
Identifikator ISSN: 2079-4991
KITopen-ID: 1000087873
HGF-Programm 37.03.01 (POF III, LK 01) Catalysts and Mechanisms
Erschienen in Nanomaterials
Verlag MDPI
Band 8
Heft 11
Seiten Art. Nr.: 892
Schlagwörter gas sensors, surface-loading, DRIFT spectroscopy, X-ray absorption spectroscopy, Fermi-level pinning
Nachgewiesen in Dimensions
Web of Science
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