Sol-gel processed MoO_3 and WO_3 thin films for use as selective chemo- sensors

摘要

Selective detection of small amounts of toxic gases, such as ammonia and CO is very important to environmental monitoring as well as for medical diagnoses. MoO_3 and WO_3 have been identified as suitable materials for detecting these gases with high sensitivity. Sol-gel processed thin films of MoO_3, WO_3 and their combination have been prepared at SUNY Stony Brook by the hydrolysis of metal alkoxide precursors followed by spin coating and were deposited on alumina heater/electrode containing substrates that were produced by the Brescia group. Sensing tests were carried out in the state-of-the-art gas sensor testing facilities available in Brescia, where the electrical resistance of sensor arrays was recorded as a function of gas concentration, for various combinations of gases (including ammonia, CO, NO_2, Methanol, isoprene, etc) at 10% relative humidity and at temperatures ranging from 400-500°C. The MoO_3-WO_3 composite system showed the best stability at the highest testing temperature. The sensing results obtained are correlated with the structural characteristics of the sensing films. This work has been carried out as a joint collaboration between the Advanced Materials Characterization Laboratory of SUNY Stony Brook (USA) and the Sensor Lab at the University of Brescia (Italy) and was funded by a NSF-AAAS (WISC) grant awarded to Perena Gouma.