Abstract: ZnO nano-powders were prepared by using microwave hydrolysis and constant temperature hydrolysis methods, using
Zn(CH₃COO)₂·2H₂O as the starting material. In order to improve gas sensitivities, ZnO nano-powders doped with Pt of Pd were also
prepared by using the microwave hydrolysis method. Their phase constitution and crystal structure were characterized by TEM and XRD analyses, and their
gas sensitivities were measured. results show that the microwave hydrolysis method is better than the canstant temperature hydrolysis method, for obtaining
ZnO nano-powders. The ZnO nanopowders prepared by using the two methods possess higher sensitivities to ethanol and gasoline, and the ZnO nanopowders doped
with Pt or Pd can enhance their selectivities to ethonal and gasoline, respectively.

Key words: microware hydrolysis, ZnO, nano-sized materials, gas-sensing properties, gas sensor