Hydrothermal Synthesis Of Tin-based Oxides Nanomaterials And Their Gas Sensing And Electrochemical Properties

Tin-based oxides nanomaterials have many advantages in synthesis andapplication, this caused the researcher’s extensively attention, especially in gassensors, catalysts and lithium-ion batterries, etc. In this thesis, SnO₂hierarchicalnanostructures were successfully prepared via a simple and surfactant-freehydrothermal process starting from stannous sulfate （SnSO₄） and trisodium citratedihydrate （Na₃C₆H₅O₇·2H₂O） in a suitable ethanol-water mixture. TEM and HRTEMimages showed that the obtained SnO₂products are uniform, well-dispersed, andspherical architectures, composed of tiny primary nanocrystals, and the diameters areabout50nm. The influences of the precursor compositions, reaction time, andtemperature were extensively studied. It was found that the amounts ofNa₃C₆H₅O₇·2H₂O and the volume ratio of ethanol and water played important roles indetermining the final morphologies of the products. According to the experimentalresults, a possible formation mechanism of the SnO₂hierarchical nanostructures wasproposed and the gas sensing properties of a series of SnO₂products wereinvestigated. The gas sensing results indicated that the sensor made from porous SnO₂nanostructures calcined at400℃exhibited excellent gas sensing performance tobutanol at the low temperature compared with those under higher calcinationtemperature and commercial SnO₂, which was mainly attributed to their uniquestructure, large surface areas, and more surface active sites.SnO were successfully prepared via a simple hydrothermal process, using tindichloride dihydrate （SnCl2·2H₂O） as stannous source in the presence ofhexamethylenetetramine （HMT）. TEM images showed that the obtained SnO productsare uniform and ultrathin nanosheets. Further electrochemical properties tests resultsshowed that the as-synthesized SnO nanosheets could be potentially applied as goodanodes for high-capacity rechargeable lithium-ion rechargeable batteries. Thereversible capacity was559mAh·g^-1after20cycles, even at high discharge currentdensities, the performance was comparable to the reported results, which wasattributed to the unique structure of ultrathin SnO nanosheets. According to the experimental results, a possible Li+insertion/extraction mechanism of the SnO anodematerials was discussed.