Synthesis And Application Of Low Dimensional Oxide Nano Materials

In recent years, research on the preparation and properties oflow-dimensional nanomaterials are one of the most exciting areas in materialsscience. Not only the synthesis of low dimensional materials with novelmicrocosmic structures which determines plenty of characteristic, but also thedesign of their morphology which are of much interest, especially in the fieldsof catalyst, light absorption, medicine and transmission.In this study, hydrothermal method were developed to fabricate a seriesof oxide nano-materials with low dimensional including vanadium oxidenanotubes(VO_x-NTs), titanium oxde nanotubes(TiO₂-NTs), molybdenumoxide microsphere, molybdenum oxide nanoflake and nanorod. Differentanalysis and characterization technologier were utilized to study theircomponents, structure and growth mechanism. And then study the applicationof heterogeneous chiral catalysts prepared using VO_x-NTs and TiO₂-NTs assupport coating with chitosan (CS) ad Pd in acetophenone transferhydrogenation reaction. Now sum up as fellows.1．Vanadium oxide nanotubes (VO_x-NTs) have been synthesized by usingn-butylamine as structure-directing template and V₂O₅ as precursor under the optimize conditions (hydrothermal temperature: 150～160℃, hydrothermaltime: 5～7days, the molar ratio of V₂O₅ to n-butylamine is 1:1) with innerdiameters ranging from about 20 nm, outer diameters about 100nm andseveral micrometers in length. The formation of VO_x-NTs is controlled by the'rolling' mechanism and temperature is primary driving force for rolling.Butylamine remain between the wall sheets of vanadium oxide to support theframework of nanotubes. Heterogeneous chiral catalysts Pd-CS/VO_x-NTspossess higher catalytic activity and enantioselectivity which were preparedthough sedimentation and dipping method with 30ml NaOH, 0．1ml PdCl₂ Fortransfer hydrogenation of acetophenone, at 50℃reaction for 8 h, the ee valueto (R)-1-phenylethanol obtained 62．4%.2．TiO₂ nanotubes with high specific surface area (169．62 m²?g^-1 )weresynthesized by hydrothermal method using commercial TiO₂ and 10mol/LNaOH. The nanotubes are in an amorphous state with diameters between 2and 10nm. Heterogeneous chiral catalysts Pd-CS/TiO₂-NTs possess highercatalytic activity and enantioselectivity than Pd-CS/VO_x-NTs which wereprepared though sedimentation and dipping method with 30ml NaOH, 0．1mlPdCl₂ For transfer hydrogenation of acetophenone, at 50℃reaction for 8 h,the ee value to (R)-1-phenylethanol obtained 81．7%. Through six hours'acrylic acid (300 mg/L) degradation tests, TiO₂-NTs calcined at 600℃showed a activity about 45．9%.3．MoO_x nanoflake and nanorod mixed system were prepared by (NH₄) ₆MoO₂₄·4H₂O and CTAB under the hydrothermal conditions (100℃,3days). MoO_x microsphere diameters from 2．79 to 13μm have beensynthesized under hydrothermal treatment (hydrothermal condition:130℃,3days) by using n-butylamine and MoO₃．These microspheres were composedof nano dimensional particles. They are in an amorphous state.