Chemisorption and electrochemical reactions of SO2 on modified SnO2 electrodes

Molybdenum and tungsten oxide based gas sensors for high temperature detection of environmentally hazardous sulfur species

“…The sites that are exposed to SO 2 do not form any compound with the cations, and thus, the possibility of further oxidation of SO 3 to SO 2− 4 may be ruled out. It is assumed that the final product (SO 3 ) is released from the surface immediately at these testing temperatures, in accordance with that discussed in previous literature and the post-mortem XPS analysis completed in this work [18,71,73,[83][84][85][86][87] It may be noticed in Fig. 5 that all the responses show a quick change in resistance followed by a slower exponential decrease in the response to the equilibrium level, which representative of a diffusion-controlled process.…”

“…It has been shown that these oxygen vacancies not only facilitate adsorption of molecular oxygen, but also SO 2 gas at high temperature. This aspect is important since thermal desorption of the SO 2 from metal oxide surfaces has been shown to increase at temperatures >500 • C and most oxide surfaces are typically free of O 2− and SO 2 by 1000 • C [18,83,84] The redox reaction is initiated with the SO 2 interaction with the surface. As discussed above, it is assumed that the nano-SrMoO 4 surface vacancy sites assist in trapping the sulfur species.…”

Ultrasensitive NO2 Sensor Based on Ohmic Metal–Semiconductor Interfaces of Electrolytically Exfoliated Graphene/Flame-Spray-Made SnO2 Nanoparticles Composite Operating at Low Temperatures

“…Since the inception of metal oxide gas sensors decades ago, tin oxide (SnO 2 ) has been the most widely used material in commercial gas-sensing applications despite wide availability of other metal oxides due to its moderate conductivity, diverse gas sensitivity, low cost, and good stability. − Much research in gas-sensing fields is thus still focusing on further enhancing the gas-sensing performances of SnO 2 -based gas sensors by fabrication of SnO 2 nanostructures and incorporation of effective additive materials. Many types of additives including transition metals, semiconducting or semimetal elements, light elements, noble metals, rare-earth elements, as well as organic materials have been included in SnO 2 host and extensively studied for sensing of various oxidizing and reducing gases. − Among these, graphitic nanocarbon, particularly graphene, has recently earned much attention due to its large specific surface area, strong interaction with electron donating or accepting gas molecules adsorbed on its surface, high conductivity, and low cost. − The addition of graphene into semiconducting metal oxide, particularly SnO 2 , has been shown to be an effective means to improve gas response, selectivity, response/recovery times, as well as working temperature. − Table reports the gas response of graphene-based composite prepared by various chemical and physical routes. The gas response is defined in the footnotes to Table .…”

H2 Sensing Response of Flame-spray-made Ru/SnO2 Thick Films Fabricated from Spin-Coated Nanoparticles

“…Semiconducting metal oxides in general, and SnO 2 in particular, have been investigated extensively for the purpose of practical applications such as gas leak detecting and environmental monitoring. It is a wide band gap (3.6 eV) n-type semiconductor and the best-understood prototype of oxide-based gas sensors for the detection of reducing gases (like CO [ 1 - 6 ], H 2 [ 6 - 12 ], SO 2 [ 13 , 14 ], NH 3 [ 15 , 16 ], H 2 S [ 11 , 17 ], C 2 H 5 OH [ 18 ]) or oxidizing gases (like NO 2 [ 1 , 5 , 12 ], O 2 [ 19 , 20 ]) in air. The detection of H 2 gas in different industrial applications is especially important for safety reasons.…”