Room-temperature hydrogen sensitive Pt-SnO2 composite nanoceramics: Dormancy and a practicable regeneration method

Dormancy has been suggested to be used for metal oxide gas sensors to specifically refer to their response decrease or disappearance after long periods of inactivity at room temperature. In this paper, 1 wt% Pt-SnO 2 composite nanoceramics with especially strong responses to hydrogen-containing atmospheres at room temperature, e.g. a response of 11170 to 1 % H 2 -20 % O 2 -N 2 , were successfully prepared through pressing and sintering. A clear dormancy has been observed for them as their responses decreased seriously with time when they were stored in ambient air at room temperature. Commercial ceramic heating plates (Metal Ceramics Heater, MCH) of 10 mm x 10 mm were attached to bars of 1 wt% Pt-SnO 2 composite nanoceramics. Dormant bars after 12 months of storage were completely regenerated through a heat-treatment of 200 degrees C for 10 min by attached MCH ceramic heating plates. According to X-ray photoelectron spectroscopy analyses, the formation of hydroxyl groups on SnO 2 in Pt-SnO 2 composite nanoceramics and deposition of impurity gases like H 2 S were proposed responsible for the dormancy, and their removal through mild heat-treatments result in the regeneration. It is suggested that heaters like commercial MCH ceramic heating plates should be included in future room-temperature gas sensors to provide a practicable regeneration from dormancy when needed.