Preparation And Properties Of Zinc Hydroxystannate And Its Composites

Zinc hydroxystannate (ZnSn(OH)6), a class of perovskite-structured hydroxide material, is well-documented as efficient photocatalysts, nontoxic flameretardants and smoke suppressants and therefore it is also considered as one of the most promising functional materials to solve the energy and environmental problems. In this paper, ZnSn(OH)6and micro/nanostructured ZnSn(OH)6/ZnO composite architectures were synthesized through simple hydrothermal route and low-temperature aqueous solution route, respectively. Parameters in the preparation process were discussed and growth mechanism of the samples was explored and controllable synthesis of the products was realized. The main conclusions are as follows:Firstly, the effect of preparation parameters on the morphology of ZnSn(OH)6regular octahedrons and growth mechanism of the regular octahedrons were studied in hydrothermal solution using SnCV·5H2O, NaOH and ZnO flower-like structures as raw materials.1) The ratios of Sn4+/OH", molar ratio of Zn/Sn and hydrothermal reaction time play important role in the morphology of the products. With the increase of the concentration of OH-, the ZnSn(OH)6urchins-like structures disappear. When the molar ratio of Zn/Sn changes to1:2or2:1, the edges and corners of ZnSn(OH)6regular octahedrons become coarse and ZnSn(OH)6urchins-like structures disappear, too. Hydrothermal reaction time determines the size and distribution of ZnSn(OH)6urchins-like structures.2) Growth of the ZnSn(OH)6regular octahedrons follow the principle of dissolution-recrystallization mechanism. Dissolution and recrystallization process of ZnO flower-like structures determines the morphology of the products.3) ZnSn(OH)6regular octahedrons have an excellent property for rhodamine B degradation and degradation percentage can get up to86%in100minutes.Secondly, the effect of preparation parameters on the morphology of ZnSn(OH)6cubes was studied in low-temperature aqueous solution using zinc acetate, stannous chloride, NaOH and hexamethylene tetramine as raw materials. The photocatalytic activity of the products was also investigated.1) Results show that the concentration of OH-and reaction temperature play important role in the morphology of the products. With the increase of the concentration of OH", the edges and corners of ZnSn(OH)6cubes are coarse and unconspicuous. When the reaction temperature is above60℃, ZnSn(OH)6cubes are partly dissolved and a lot of small ZnSn(OH)6cubes appear by secondary nucleation and growth.2) ZnSn(OH)6cubes have an excellent property for rhodamine B degradation and degradation percentage can get up to85.3%in100minutes.Thirdly, the effect of parameters on the morphology of micro/nanostructured ZnSn(OH)6/ZnO composite architectures and growth mechanism of the architectures were studied in hydrothermal solution using SnCl4·5H2O, zinc acetate and NaOH as raw materials.1) Micro/nanostructured ZnSn(OH)6/ZnO composite architectures are comprised of ZnSn(OH)6microcubes and ZnO nanorods. The concentration of the reactants plays an important role in the morphology of the products.2) Co-nucleation process determines the morphology of the products. When the temperature is below200℃, stability of micro/nanostructured ZnSn(OH)6/ZnO composite architectures is excellent.3) ZnSn(OH)6/ZnO composite architectures have an excellent property for rhodamine B degradation and degradation percentage can get up to100%in80minutes.Finally, micro/nanostructured ZnSn(OH)6/ZnO composites have been prepared in situ growth in the low-temperature aqueous solution based on previous research. Results show that ZnSn(OH)6/ZnO composites are comprised of ZnSn(OH)6cubes and spindle-like ZnO nanostructures. The ZnO nanostructures are well-distributed on the surfaces of ZnSn(OH)6microcubes. ZnO content and the concentration of OH" have great influence on the morphology of the products. Compared with ZnSn(OH)6microcubes, ZnSn(OH)6/ZnO composites have a better property for rhodamine B degradation and degradation percentage can get up to92.5%in100minutes.