Enhancement of NH₃ sensing performance in flower-like ZnO nanostructures and their growth mechanism

ZnO nanostructures hold substantial promise for gas-sensing applications owing to their outstanding ethanol sensing performance, yet their sensing performance toward NH₃ has rarely been reported. Here, we report on a successful preparation of sunflower-like ZnO nanostructures and ZnO nanoparticle via a facile hydrothermal method, and demonstrate that the ZnO nanoflowers have high gas-sensing performances toward NH₃ under a low concentration of 10-50 ppm. Further structural characterization reveals that the sunflower-like nanostructure comprises six triangles-like and one sphere-like nanostructures, and the triangle-like nanostructure is single crystalline with {0 0 1} crystal face. As a consequence of their unique morphology, the nanoflowers show much improved NH₃ sensing performances than the nanoparticles with a high sensitivity of 49.5.