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-μm 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 H₂ in air in a month, the sensor after aging treatment have detected 100 ppm H₂ 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.