DRIFT studies of thick film un-doped and Pd-doped SnO2 sensors: temperature changes effect and CO detection mechanism in the presence of water vapour

Structure and chemistry of surface-doped Pt:SnO2 gas sensing materials

“…[23][24][25] Complementary to the structural evaluation the surface chemistry of gas sensing layers can be studied by operando diffuse reectance infrared Fouriertransform spectroscopy (DRIFTS), revealing surface species actively interacting with or caused by the atmosphere, such as carbonylic species on the noble metal surface, carbonates, hydroxyls or M-O overtones on SnO 2 , which are considered to be fundamental for understanding the gas reception mechanism. 9,22,[26][27][28] The potential of these methods was demonstrated when examining SnO 2 :Pt which was doped before the nal calcination steps. 20 The structural evaluation by XAS showed that Pt replaces Sn 4+ ions in the SnO 2 lattice and that it is atomically distributed on the surface and in the bulk of the whole material.…”

“…All samples were measured in diffuse reectance geometry using a mirror optic (Praying Mantis, Harrick) with a home-made operando cell placed inside, which allows simultaneous resistance and spectroscopic measurements. 9 Single channel spectra were recorded averaging 512 scans with a spectral resolution of 1 cm À1 . The as obtained single channel spectra were processed with Bruker's OPUS soware (version 7.2).…”

In Situ and Operando Spectroscopy for Assessing Mechanisms of Gas Sensing

“…These include infrared spectroscopy (transmission-absorption) on pellets and self-supporting disks of sensing material [142,161,162] , Raman spectroscopy on pressed pellets [163][164][165] , diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), [28,[166][167][168][169][170] and emission infrared spectroscopy (IRES) [99,171] on thick film sensors (Figure 11). …”

“…[172] DRIFTS and IRES provide a very important advantage over conventional FTIR spectroscopy in that they can be applied directly on the heated sensing element, and hence the spectroscopic and electrical data can be obtained simultaneously and directly (on the thick films of the sensing layer). DRIFTS also allows observation of the gaseous molecules in the pores of the sensor material, [168,170] which enables on-line (in situ) analysis of possible reaction products. The radiation emitted by the heated sensor is used as an IR source in IRES; the emitted radiation is collected from only a small area (ca.…”

Halbleitergassensoren: Trockensynthese und Anwendung

“…[14] A. Tricoli, A. Teleki, und M. Righettoni Aufsätze pelten Debye-Länge lagen, konnten die untere Nachweisgrenze und die Empfindlichkeit verbessert werden. [29][30][31][32] Fein auf der Oberfläche des Metalloxids dispergierte Katalysatornanopartikel wie Pt, [33][34][35] Pd, [33,36,37] Ag, [38,39] Ru [40] und Au [41,42] erhöhen die Empfindlichkeit noch weiter, hauptsächlich durch Spillover-Effekte. Die Langzeitstabilität dieses hochempfindlichen Materials aus Oxid [30,32,43] und Dotierstoff [41,44] bei Betriebstemperatur (gewöhnlich 250-600 8C) ist jedoch problematisch.…”