Preparation of tungsten oxide-tin oxide nanocomposites and their ethylene sensing characteristics

A novel method for preparation Of WO3-SnO2 nanocomposite was described. 0.3-10.0 wt.% WO3 was incorporated into the SnO2 powder by precipitation of hydrated WO3 from ammonium tungstate precursor solution containing SnO2 powder. This preparation method resulted to uniform mixing of similar to 35 nm WO3 and similar to 100 nm SnO2 nanoparticles as revealed by direct observation using a transmission electron microscope, and by performing elemental dot mapping. Upon calcination to 500 degrees C, both cassiterite SnO2 and monoclinic WO3 were stable, and no other crystalline phase was observed. To evaluate gas sensing performance, the powders were formed into thick-film sensors using a screen printing technique. It was found that the gas sensitivity of the SnO2 base was enhanced when very small amount of the WO3 (0.3 wt.%) was incorporated. The 0.3 wt.% WO3-SnO2 sensor was very sensitive to 2-8 ppm ethylene at optimum operating temperature of 300 degrees C. The sensitivity decreased with increasing amount of the WO3. (c) 2006 Elsevier B.V All rights reserved.