Layered mesoporous SnO2 for effective ethanol detection at reduced working temperature

Tin oxide is widely studied for ethanol sensing because of its high sensitivity and environmental benignity; yet its operating temperatures generally exceed 200 degrees C to achieve an acceptable overall sensing performance. In this study, we report a layered mesoporous aggregate of SnO2 nanocrystals 3-5 nm in size, which is synthesized by oxidizing metallic tin particles in a mixed aqueous solution of HNO3 and H2O2 at 80 degrees C. The aggregate calcinated at 300 degrees C possesses a high specific surface area of 135 m(2) g(-1), and 0.182 cm(3) g(-1) mesopores ca. 2.5 nm in size. At an operating temperature of 180 degrees C, the SnO2 aggregate exhibits a response of 110 towards 100 ppm ethanol in air. At an even lower working temperature of 140 degrees C, an ideal overall sensing performance is achieved: a response of 37, a response/recovery time of 26/21 s, together with high selectivity and stability. The layered mesoporous architecture with a high specific surface area contributes to the high response at low operating temperatures. Besides, with increasing operating temperatures from below to beyond 150 degrees C, it takes much a longer time to achieve a total recovery in resistance. The ethanol sensing mechanism is thus believed to change accordingly from the direct adsorption one to the oxygen ionosorption model.

Automated summary

In this study, a layered mesoporous aggregate of tin oxide nanocrystals with high specific surface area and mesoporous structure was synthesized. The tin oxide showed high ethanol sensing performance at low temperatures, with high selectivity and stability. The ethanol sensing mechanism changed with increasing operating temperature.