In situ diffuse reflectance infrared spectroscopy (DRIFTS) study of the reversibility of CdGeON sensors towards oxygen

In Situ and Operando Spectroscopy for Assessing Mechanisms of Gas Sensing

“…Moreover, sometimes the spectroscopy as well as on-line gas analysis seems to represent only secondary processes that are not responsible for the sensing. We will give two examples, one for operando XAS data and the other 2) propane in dry/wet air 1) water dissociation mediated by ionosorbed oxygen; 2) reaction of propane with ionosorbed oxygen Pd/SnO 2 [168] CO/dry and humid air role of surface hydroxy groups in CO oxidation; CO reaction with ionosorbed oxygen CdGeON [28,166] O 2 in N 2 filling of oxygen vacancies; change of the Ge coordination number XAS SnO 2 and Pd/SnO 2 [176,194] CO Reviews a typical problem with on-line gas analysis. Figure 16 a, b [176] shows the correlation between the electrical conductance and the oxidation states of Pd and Sn during cycling of a Pd-SnO 2 film in H 2 and O 2 gas mixtures.…”

“…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). …”

Influence of annealing temperature on the CO sensing mechanism for tin dioxide based sensors–Operando studies

“…Recently, having catalytic and sensing application in mind, Amalric-Popescu and Bozon-Verduraz [4] after thoroughly reviewing the available literature made an attempt to establish the present state of the art in the field of the influence of the pre-treatment (temperature, oxygen background) on the properties of tin dioxide powders. However, experiments have always been performed under static conditions (exposure) or after outgassing/evacuation, which mismatches with the optimal conditions for measuring sensors performance.DRIFT experiments have been already performed in the past for the characterisation in real conditions of powders [5][6][7][8] and of real sensors; the latter were even performed at sensors' working temperatures [9][10][11][12]. Generally, during the gas sensing process with metal oxide based sensors the determining factors are the different ways by which charge carriers are exchanged with the conduction band of the sensing material because of the usual manner in which the effects are recorded, id est by measuring the resistance changes upon gas exposure [13].…”

SiC-based MIS gas sensor for high water vapor environments

“…Nevertheless, the sensing mechanism of these two small hydrocarbons might be a combination of both adsorption mechanisms or the result of quite complicated one and, so, it is difficult to be deduced by only one type of measurement. Thus, additional studies with analytical techniques for atmospheric pressures, such as mass spectrometry [37] and/or in situ DRIFT (diffuse reflection infrared Fourier transform) spectroscopy [38,39], which have already provided very useful information to better understand the detection mechanism of MIS devices to hydrogen and carbon monoxide, are needed to elucidate the sensing mechanism toward these gases.…”