In situ Raman spectroscopy study of NO2 adsorption onto nanocrystalline tin(IV) oxide

Abstract

A study of the adsorption of NO 2 on a nanocrystalline tin(IV) oxide powder was carried out in situ by Raman spectroscopy. Heat treatment up to 300°C of the sample in NO 2 revealed the complexity of the surface reactions. Thus, numerous NO x adsorbed species were evidenced such as weakly adsorbed nitrates, NO 2 dimers, nitrites, bridging and various bidentate nitrates. The stability of these last species has been related to the N O bond strength. It has been proposed that the nitrite species are responsible for the SnO 2 response in the presence of NO 2 traces.

Application of Raman Spectroscopy to Working Gas Sensors: From in situ to operando Studies

“…Despite the potential of Raman spectroscopy for studying gas sensors at work, only a few In situ Raman studies on metal oxide gas sensors have been published [21,22,23,24,25,26,27,28,29,30,31,32], which in part were done with simultaneous recording of the resistance [22,23,24]. For nanocrystalline SnO 2 [22] and CuO/SnO 2 [23] at 100 °C, upon exposure to 300 ppm H 2 S, the reversible formation of sulfide species (SnS x , Cu 2 S) was reported, which was correlated with the simultaneously measured decrease in resistance ( operando -pellet approach).…”

“…Despite the potential of Raman spectroscopy for studying gas sensors, only a small number of studies have been published, compared with other characterization techniques (e.g., IR spectroscopy). Previous work published in the context of metal-oxide gas sensors ranges from the (ex situ) use of Raman characterization [13,14,15,16,17,18,19,20] to In situ Raman studies [21,22,23,24,25,26,27,28,29,30,31,32] and operando Raman studies [5,6,33,34,35,36], part of which were done in combination with operando UV-Vis spectroscopy [6,35]. In these studies typical gas sensor materials, such as SnO 2 , WO 3 , and In 2 O 3 were investigated towards a variety of target gases, e.g., H 2 S, CH 4 , H 2 , CO, NH 3 , NO 2 , ethanol (EtOH), and acetaldehyde (acetald.).…”

Gravity‐Driven Multiple Collision‐Enhanced Catalytic Soot Combustion over a Space‐Open Array Catalyst Consisting of Ultrathin Ceria Nanobelts

“…In the presence of 300 ppm NO, the soot oxidation is facilitated by the NO x species. The in situ Raman spectra of CeO 2 ‐NA clearly show a new band at 912 cm −1 (Figure D), which could be attributed to the adsorbed NO 2 dimers (ONONO 2 ) . In the coexistence of NO and O 2 , NO can be oxidized by both the gaseous oxygen and the active oxygen species on catalyst surface, forming NO 2 species, which can further transform to NO 2 dimers.…”

Nanopowders and nanostructured oxides: phase transitions and surface reactivity

“…SnO 2 nanocrystals 53 were subjected to cyles of dry air (1000 ppm NO 2 in dry air at various temperatures) from room temperature up to 300°C. 54 New bands were observed when NO 2 was present in the atmosphere (Fig. 5).…”