Synthesis of Au catalysts modified Zn-doped SnO2 nanorod clusters for low-temperature gas sensing applications
In the thesis, we mainly described the synthesis of novel Zn-doped SnO2 nanostructures, the surface decoration with tiny Au nanoparticles (NPs), and the CO gas sensing applications. With precisely controlled hydrothermal processes and unique Au decoration techniques, a series of highly CO-sensitive catalytic Au NPs decorated Zn-doped SnO2 nanorod clusters were successfully synthesized. Regarding the structural design and syntheis, doping of Zn into the SnO2 lattices is evidenced as a workable strategy not only for optimizing the CO sensitivity from the view point of defect chemistry, but for effectively varying the morphology and size of the prepared SnO2 nanorod clusters. From the observation using electron microscopes, the formed Zn-doped SnO2 nanorod clusters possess excellent urchin-like hierarchical nanostructures with an extremely high surface to volume ratio, which providing a great amount of channels for gas diffusion and large area for gas absorption. In addition, the diameter of each single nanorod is very close to the expected ideal size of nanosensors. For further enhancing the sensing performance, Au NPs synthesized by a one-step or two-step method successfully decorate the Zn-doped SnO2 nanorod clusters. It was also foud that differnt sample collecting techniques (a boiling or centrifugal method) would lead significant difference in the amount and dispersion of the Au NPs. From the analyses of CO sensing performance, remarkable response and recovery features with a highest sensitivity was found at a relatively low working tempeature for the Au NPs decorated Zn-doped SnO2 nanorod clusters prepared by a two-step hydrothermal method and collected by centrifugation. The structural investigations clearly evidence that the well-despersed Au NPs play as a very critical role for providing a great amount of catalytic sites for targeting gas. The present results conclude that the Au NPs decorated Zn-doped SnO2 nanorod cluster is one of the most promising nanomaterials for fabricating advanced low-temperature gas sensors.