A study of the catalytic and vapour-sensing properties of zinc oxide and tin dioxide in relation to 1-butanol and dimethyldisulphide

Thick film sensors were produced from pastes of tin dioxide, zinc oxide and a mixture of the two materials. The sensors were operated at a temperature of 350 degrees C and their electrical responses to 1-butanol and DMDS in t he concentration range 1-100 vpm were monitored. Thin film tin dioxide sens ors were also fabricated by evaporating tin metal through an oxygen plasma and the resulting sensors tested for their responses to the vapours. A numb er of commercially available Figaro sensors were also tested against the sa me vapours for comparison. The sensors comprising tin dioxide and zinc oxid e combined gave the largest changes in electrical resistance when exposed t o the test vapours. The catalytic effect of tin dioxide, zinc oxide and a c omposite material of the two upon selected test vapours was elucidated usin g GC-MS and H-NMR spectroscopy. The results offer some insight into the mec hanisms by which metal oxide semiconductors catalytically break down organi c vapours at elevated temperatures. The results also show that these mechan isms differ in the case of tin dioxide and zinc oxide. (C) 1999 Elsevier Sc ience S.A. All rights reserved.