Template-free synthesis of nanosheets-assembled SnO2 hollow spheres for enhanced ethanol gas sensing

The specific structure of hollow sphere with hierarchical structure is beneficial to facilitate the gas diffusion and supply more active sites for improving gas sensing performance. In this paper, we report the fabrication of hierarchical SnO2 hollow spheres assembled by ultrathin nanosheets (SnO2 NSHSs) via a template-free hydrothermal method. The formation mechanism and microstructures of the SnO2 NSHSs were discussed and characterized in detail. The SnO2 NSHSs sensor shows a high response and ultrafast response time (5 s) towards ethanol. Furthermore, the SnO2 NSHSs gas sensor also exhibits a low detection limit of ppb level. The enhanced sensing performance can be attributed to the unrestricted gas diffusion in the hierarchical hollow spheres and plenty of active sites on the ultrathin SnO2 nanosheets.