Template-free hydrothermal synthesis of ZnO microrods for gas sensor application

Zinc oxide microrods with controlled diameter were prepared without the addition of template and additive by a simple hydrothermal route only using Zn(CH3COO)(2)center dot 2H(2)O as a precursor. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and electron diffraction (ED). The crystal structure of prepared ZnO microrods is hexagonal phase polycrystalline with zincite structure. With the increase of the precursor concentration from 0.05 M to 0.6 M, the diameter of the ZnO microrods increased from 1 mu m to 5 mu m. A localized oriented attachment mechanism was prepared to account for the formation of ZnO microrods. The gas-sensing performance experiments indicated that the prepared ZnO microrods exhibited highly sensitive, selective gas-sensing properties, and good stability to acetone vapor. The response and recovery time of ZnO-based gas sensor to 100 ppm acetone vapor are 12 s and 18 s, respectively. The mechanism of the ZnO-based sensor was investigated.