Fabrication of flower-like ZnO nanosheet and nanorod-assembled hierarchical structures and their enhanced performance in gas sensors

Nanosheet-assembled hierarchical flower-like ZnO nanostructures formed from closely packed nanosheets have been fabricated from an ethanol-assisted hydrothermal route at a temperature of 140 degrees C. It was found that the solvent played a key role in the formation process of the hierarchical ZnO nanostructures in this reaction system. Most importantly, the as-prepared nanosheet-assembled flower-like ZnO (S-1) nanostructures exhibited excellent sensing properties towards acetone, up to 35.1 within 0.5 s towards 500 ppm acetone, which were much better than those of nanorod-assembled flower ZnO nanostructures (S-2) and ZnO microspheres (S-3). A detailed investigation revealed that a large number of almost invisible pores existed in the ZnO superstructures, which play a key role in the transport pathways of small molecules, resulting in nanosheets with a high level of sensing activity.