Hierarchically mesoporous SnO2 nanosheets: Hydrothermal synthesis and highly ethanol-sensitive properties operated at low temperature

In this contribution, hierarchical tin dioxide (SnO2) nanosheets were successfully synthesized via a simple, cost-effective and environment-friendly hydrothermal method at a relatively low temperature (90 °C) after calcination in air. The post-heat treatment not only improved the crystallinity, but also increased the visible emission (refer to intrinsic crystal defects) of the hydrothermal products, which were proved by X-ray diffraction and room temperature photoluminescence, respectively. Electronmicroscopy analysis and nitrogen adsorption-desorption results confirmed the mesoporous feature of these nanosheets. Gas sensors based on these SnO2 nanosheets exhibited high response, fast response-recovery and good selectivity to 1-1000 ppm ethanol vapor at a relatively low operating temperature (165 °C). The excellent ethanol-sensing property, especially high response value can be mainly attributed to the mesoporous texture, characteristically small grain size, abundant surface defects, and the plane-contact feature between the neighboring SnO2 nanosheets.