| Recently, with the growing attention to environmental problems and the increase of the standard of living, there are imperative needs for gas sensors with high sensitivity and excellent selectivity for monitoring toxic and combustible gas. Up to now, with the developing of the nanotechnology, the application of nano-materials to be design of gas sensors is one of the most active research fields. In this paper, ZnO, SnO2 and complex metal oxides nanomaterials have been synthesized by solid-state chemical reaction. The gas-sensing of prepared product have also been investigated.1. A series of one-dimension (1D) ZnO nanorods were prepared by one-step solid-state chemical reaction with zinc acetate, sodium hydroxide and different surfactants under the suitable experiment conditions. At the same time ZnO doped with rare earth oxides(REOs) were prepared by a similar approach as solid-state chemical reaction, except for addition of Nd(acac)3?3H2O, Ce(acac)3?2H2O, Nd(acac)3?3H2O into agate mortar with zinc acetate before the reaction, respectively. The compositions of samples were determined by XRD. The rod-like morphology of samples was observed by TEM and SEM. Sensitivity characteristics of the undoped and REOs-doped ZnO nanorods were investigated. The results show that the gas-sensing properties of ZnO were good for ethanol vapor. But the sensors of REOs-doped ZnO nanorods present much higher sensitivity and better selectivity as well as shorter response-recovery time to ethanol vapor than undoped ZnO nanorods.2. Semiconductor SnO2 nanoparticles were prepared by solid-state chemical reaction at ambient conditions in one step and two steps. Semiconductor SnO2 nanorods were prepared by low-heating solid-state chemical reaction in two steps with surfactant PEG-400. The compositions of samples were characterization by XRD. The morphology of samples was observed by SEM and TEM. The gas-sensing properties of samples were studied. .Results show all the SnO2-based gas sensors are realized the detection of ethanol with high sensitivity and good selectivity as well as short response-recovery time. But the SnO2 nanorods present better reproducibility.Therefore solid-state reaction technique at ambient conditions may be a new way to prepare gas-sensing materials with excellent properties.3. Semiconductor complex oxides of CdFe2O4, ZnFe2O4, Zn2SnO4 and Cd2SnO4 were synthesized by solid-state chemical reaction of metallic salts and the sodium hydroxide. The compositions of samples were characterization by XRD. The morphology of samples was observed by SEM. The gas-sensing properties of samples were investigated. The sensors based on the complex oxides nano-materials show good sensitivity to ethanol gas at different operating temperature. In order to improve the gas-sensing characteristics of gas sensors, complex oxides doped with noble metal Pd were synthesized by the simple dip-coating method. Sensitivity characteristics of the sensors were also investigated. The results show that the sensors doped with Pd present much higher sensitivity and better selectivity as well as shorter response-recovery time to ethanol vapor than undoped ones, indicating that the promoting effect of Pd is excellent in the case.
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