SnO₂ Nano-materials Preparation And Characterization By Hydrothermal

SnO₂ is a kind of n-type broadband semiconductor(3.6eV),with a regular tetrahedron rutile structure,has been widely used in gas sensors,transparent electrodes of solar cells,optical technology,and catalytic oxidation of organic matter.In this work, SnO₂ nano-materials,including nano-powders,nano-microspheres,micro-rods and some other morphology of SnO₂ nano-materials were prepared by hydrothermal methods and were characterized by field emission scanning electron microscope(SEM),transmission electron microscopy(TEM) and X-ray diffraction(XRD),the main results as follows:(1) SnO₂ nano-particles were prepared by hydrothermal under different reaction time (2h,6h,24h),and gas-sensing properties were also measured.The results show that the hydrothermal powders for 6 hours has a uniform particle size distribution and the best dispersion,with an average grain size of 6nm.Longer or shorter time is not conducive to the preparation of powders.If reaction time is too short,the small-sized pariticles aggregation seriously;on the other hand.the particles continue to grow.At the same time, the gas-sensing properties to alcohol of the as-prepared SnO₂ nano-powders are better than that of commercial gas-sensing SnO₂,the particles obtained for 6 hours have the best gas-sensing properties.The too short or too long reaction time will reduce the gas-sensing properties of the materials.(2) SnO₂ nano-spheres,which size is about 0.4μm～1.5μm and crytal structure are polycrystalline,were prepared by hydrothermal.The effects of CTAB,hydrothermal reaction time,reaction temperature and the amount of tartaric acid on the morphology and structures of the products were studied.The results show that CTAB and the reaction temperature is important to the size and crystal structure.At last,a possible self-assembled formation mechanism was given.(3) One-dimensional micro-SnO₂ rods were prepared,SEM,TEM and XRD analysises were used to characterize the products.The results show that the micro-rods have a diameter of 1μm and a length about 30-80μm.A brief analysis of the micro-rods formation mechanism was proposed,and molten salt medium plays the key role to the growth of one-dimensional structure. (4) A number of other shapes products,for example,leaves,ear-shaped,flower-like and cubic-like and so on are occasionally obtained.SEM and XRD analysis are used to characterize their morphology and composition,their formation mechnisem are under studies.