Pt loaded alumina ceramic catalysts for micro thermoelectric hydrogen sensors

The micro-thermoelectric hydrogen sensor (micro-THS) detects the hydrogen gas working with the thermoelectric effect of SiGe thin film and the Pt-catalyzed exothermic reaction of hydrogen oxidation. Integration of Pt/alumina ceramic catalyst on the membrane of the micro-THS was evitable to ensure the high sensitivity and long-term stability of the sensor. The various compositions of Pt/alumina ceramic catalysts were milled by a ball-mill technique to improve the dispersion of the catalyst, and were mixed with conventional organic vehicle like paste. The paste was deposited on micro-THS using dispenser method and the effects of the ball-mill technique and catalyst composition on the sensitivity, ΔV_s, of the micro-THS for the hydrogen/air mixture gas flow were investigated. The shape of ceramic catalyst became uniform, and agglomeration of catalyst powder could not be observed using ball-mill technique. The 10 mass% Pt/alumina ceramic catalyst was the optimized platinum content of the ball-milled powder paste, and the micro-THS with this catalyst produced the larger voltage signal of 12.2 mV at the operating temperature of 100°C.