Preparation And Properties Of Metal Oxides Gas-sensing Materials Prepared By Solid-state Chemical Reaction

Various flammable and toxic gases around us do harm to our health and safety. Thus, more and more attention has been focused on the study of gas sensors owning to their efficient detection for many gases. Metal oxide semiconductor gas sensors, which have simple structure, low cost, easy to transform detectable quantity into electrical signal, are widely employed in detecting toxic and inflammable gases and monitering atmospheric gases.Since 1960, the conventional semiconductor gas-sensing materials of SnO2 and ZnO have been extensively studied by many researchers, and the application of gas sensors based SnO2 and ZnO has been developed in domestic and industrial fields. But these two kinds of gas sensors still have some disadvantages up to the present, such as high power consumption, poor selectivity and shortage stability. In order to improve the gas-sensing properties of SnO2 and ZnO gas sensors, researchers prepared these two kinds of materials by various methods. In this paper, SnO2 and ZnO nano-materials have been prepared by solid-state chemical reaction using carbon microspheres and Ag/C cables as additive. The gas-sensing properties of as-prepared product have also been investigated in detail. The main content is as follows:1. Carbon microspheres were prepared by hydrothermal method employing the sucrose as the starting reagent. We report the synthesis of SnO2 and ZnO nanocrystallite from annealing precursors produced by solid-state chemical reaction using carbon microspheres as the additive. The compositions of samples were determined by XRD. The morphology of samples was observed by TEM and HRTEM. The effect of different sintering temperatures and different amounts of carbon microspheres additive on SnO2 and ZnO gas-sensing materials have studied. The results demonstrated that the microstructure of SnO2 and ZnO materials can be modified by the added carbon microspheres. The SnO2 and ZnO gas-sensors have good response to ethanol and petrol at low operating temperature. 2. We adopted the hydrothermal carbonization co-reduction process of AgNO3 and glucose to prepare Ag/C cables. Ag-doped SnO2 nanoparticles and ZnO nanorods were obtained by annealing precursor powders fabricated by solid-state chemical reaction using the as-prepared Ag/C cables as the additive. The compositions of samples were characterized by XRD. The morphology of samples was observed by TEM and HRTEM. The experimental results indicated that Ag-doped ZnO nanorods have been synthesized by oriented aggregation of single ZnO nanoparticles induced by Ag/C cables. The gas-sensing properties of sensors based on Ag-doped SnO2 nanoparticles and ZnO nanorods have been studied, the results demonstrated that Ag-doped SnO2 nanoparticles have good sensitivity to formaldehyde at low temperature and Ag-doped ZnO nanorods have good response to ethanol.