An olive-shaped SnO2 nanocrystal-based low concentration H2S gas sensor with high sensitivity and selectivity.

Olive-shaped SnO2 nanocrystals were synthesized successfully via a facile hydrothermal route, using tin dichloride hydrate, oxalic acid dihydrate and polyvinylpyrrolidone as reaction precursors, and showed great potential in the large-scale preparation of SnO2 nanocrystals. The prepared SnO2 nanocrystals were characterized using XRD, XPS, SEM, TEM and HRTEM, and showed well-defined olive-shaped tetragonal single-crystals with irregular exposed facets. The growth mechanism of the olive-shaped SnO2 nanocrystals was considered after investigating the experimental conditions and reaction time. Due to the abundant active sites on the irregular surfaces, the gas sensing performance of the prepared SnO2 nanocrystals exhibited great gas sensing properties, including high sensitivity, selectivity and stability towards H2S with a very low detection limit (less than 0.5 ppm), revealing their great potential in commercial applications for H2S gas detection.