ROMJIST Volume 20, No. 4, 2017, pp. 415-425
C.E. Simion, O.G. Florea, A. Stanoiu Gas sensing mechanism involved in H2S detection with NiO loaded SnO2 gas sensors
ABSTRACT: SnO2 loaded with 1 wt.% NiO based gas sensors, have been tested under humid background towards different H2S concentrations when operated at 350 °C. Knowing that water dissociation takes place, leading to the formation of strongly bonded surface hydroxyl groups, usually hindering the subsequent gas detection, it is of highly importance to understand the role of NiO as “OH groups trapper” element. By using complementary phenomenological investigations (simultaneous electrical resistance and work function measurements) we could emphasize the role of loading element in mitigating the water effects, further reflected through the different H2S interaction mechanisms. As such, the exposure of the SnO2 - 1 wt.% NiO sensors to different relative humidity levels was mirrored through a decrease in surface band bending due to the water donor effect and to a minor increase in the electronic affinity explained by the low adsorption of surface OH groups.KEYWORDS: NiO loaded SnO2, H2S detection, gas sensing mechanismRead full text (pdf)