Long-term stability of Pt/alumina catalyst combustors for micro-gas sensor application

Long-term stability of thick-film type Pt/alumina catalyst combustors integrated on the micro-thermoelectric hydrogen sensor (micro-THS) has been investigated. We prepared the catalyst thick films with three different thicknesses to investigate their combustion performance on the micro-device. To enhance the long-term stability, a self-heating treatment of the catalyst aging of the sensor with its micro-heater has been carried out. The performance of the sensor with the 15-mu m thick catalyst which was the thickest one in this study was less temperature dependent, and more stable for long-term operation. While the sensor without aging treatment failed to detect 100 ppm H-2 in air in a month, the sensor after aging treatment have detected 100 ppm H-2 in air over 3 months. The degradation of its signal level for 1 vol.% and 100 ppm was below 10% and 15%, respectively. Nano-level microstructure observation of the catalyst investigating the Pt nano-particle dispersion has been carried out to discuss with mechanism of the performance degradation and the role of aging treatment on the stability of the sensing performance of the sensor. (C) 2008 Elsevier Ltd. All rights reserved.