Nanosheet-assembled hierarchical SnO2 nanostructures for efficient gas-sensing applications

[Display omitted] In this paper, blooming, semi-blooming and porous semi-blooming SnO2 nanoflowers were applied to test the gas-sensing performance towards ethanol. •Blooming, semi-blooming and porous semi-blooming SnO2 nanoflowers were prepared via facile hydrothermal conditions.•The three nanosheet-assembled hierarchical SnO2 nanostructures were applied to test the ethanol gas-sensing performances.•It is found that the sufficient amount of gas diffusion matters for the gas sensing rather than the fast gas diffusion speed.•Gas-sensing mechanism was discussed in detail.•The mesoporous semi-blooming nanoflowers based sensor was applied to monitor the existence of beer by using a simple integrated device. The manner how nano building blocks assemble into hierarchical architectures exerts a tremendous influence on gas-sensing performance of the metal oxides. Here, we focus on tuning the 2D SnO2 nanosheets into 3D hierarchical nanoflowers by manipulating the presence of NaOH, and investigate their gas-sensing functionalities. We find that the blooming SnO2 nanoflowers assembled by ultrathin nanosheets (∼50nm) are shrunk into semi-blooming state, and that the semi-blooming nanoflowers based sensor shows enhanced gas-sensing performance towards the ethanol, which is attributed mainly to the confined effect due to numerous nano or micro reaction rooms by keeping oxygen and ethanol molecules to complete gas-sensing reactions. While the semi-blooming nanoflowers turn into ordered mesoporous via thermally removing the periodically arranged polyvinyl pyrrolidone micelles, their gas-sensing performance is found to be improved dramatically, indicating that sufficient amount of gas diffusion is crucial to gas-sensing properties rather than the fast gas diffusion speed. As a final verification, we fabricate the sensors using the mesoporous semi-blooming SnO2 nanoflowers and successfully monitor the existence of beer by a simple integrated device, making it a promising candidate in detecting drunk driving.