Surface Characterization and the Gas Response of a Mixed, Fe2O3Fe2(MoO4)3, Oxide to Low Concentrations of H2S in Air

✍ Scribed by Ülo Kersen; Lauri Holappa

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 537 KB
• Volume: 20
• Category: Article
• ISSN: 1040-0397
• DOI: 10.1002/elan.200804342

✦ Synopsis

Abstract

The preparation and H~2~S sensing potential of thick‐films of a mixed oxide, Fe~2~O~3~Fe~2~(MoO~4~)~3~, were investigated. A Fourier‐transform infrared (FTIR) study confirmed the existence of sulfur species at the surface after the interaction of H~2~S gas with the mixed oxide. The starting material, β‐FeMoO~4~, was synthesized by a solvothermal method, followed by supercritical drying. Heat treatment of this material (oxidation) above 500 °C resulted in the formation of Fe~2~O~3~Fe~2~(MoO~4~)~3~ mixed oxide, where Fe~2~O~3~ was a by‐product. An increase in the conductivity of the films in the presence of H~2~S gas (concentration range 1–20 ppm in air) was observed with the simultaneous formation of water and sulfide ions at 225 °C. An improvement of the H~2~S sensing potential is obtained, using an intermediate short heat treatment at higher temperature (500 °C) in the beginning of recovery (desorption) phase. This intermediate high temperature, used before every expected exposure to H~2~S gas, may contribute the formation of an initial surface coverage of O^2−^.