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.