Self-Assembly And Properties Of Inorganic Oxide Mesoporous Materials

Mesoporous materials are playing the more and more important roles in catalysis, adsorption, seperation, nanoreactors, templates and photocontrolled devices etc., due to their unique pore structures and tunable properties on pore surface. Its syntheses and applications are paid more attentions. Facile and excellent synthesized routes to prepare controlled inorganic mesoporous materials, have become the key point to achieve their applications. The achievements have made in this thesis are summarized as follows:1. Fine control over the morphology and structure of mesoporous silica nanomaterials by a dual-templating approachMesoporous silica nanomaterials of different structures, including nanospheres, nanoellipsoids, helical nanorods and multi-lamellar nanovesicles, were synthesized finely-controlled, simply by taloring the weight ratio of two common surfactants (AOT and CTAB). N2 sorption analysis showed the prepared silica materials have high specific surface area, large pore volume, and uniform pore size distribution. TEM results showed ordered chrical mesopores run in the internal structure of the synthesized silica nanowires.2. Porous silica nanocapsules and nanospheres: dynamic self-assembly synthesis and application in encapsulation in situ and controlled releasePorous silica nanocapsules and silica nanospheres have been successfully fabricated by a novel combination of stabilizing condensation and dynamic self-assembly. When ethyl ether was used as the co-solvent, porous silica nanocapsules were obtained. Ethyl ether not only functioned as a dynamic template for the formation of the nanocapsule, but played a critical role in the formation of the porous shell by gasification as well. In contrast, when 2-ethoxyethanol was used, which only has a small difference in its molecular structure from ethyl ether, silica porous nanospheres were produced. The approach using ethyl ether allowed ready in situ encapsulation of organic molecules into silica nanocapsules, and the encapsulated molecules could be released in a controlled way into aqueous media.3. Self-assembly of novel mesoporous manganese oxide nanostructures and their application in oxidative decomposition of formaldehydeMesoporous nanostructures of birnessite-type MnO2 (KxMnO2) were synthesized at room temperature. It involves a redox reaction of KMnO4 and oleic acid at the O/W interface, followed by self-assembly of formed KxMnO2 nanoplatelets into KxMnO2 nanostructures. These new nanomaterials showed morphology-dependent catalytic activities for decomposition of formaldehyde with significant high activity. Complete conversion of HCHO to CO2 and H2O could be achieved at low temperatures.4. Facile synthesis of monodisperse manganese oxide nanostructures and their application in water treatmentPorous manganese oxide nanostructures with the same morphology were prepared. The phase structure of manganese oxide nanostructure was controlled by treating the precursor at different temperatures, transforming the precursor from layered manganese oxide to tetragonal hausmannite structure. Water treatment experiments indicated that the prepared manganese oxide nanomaterials exhibited higher removal capacity and rate of organic polluents in neutral solutions.5.Rapid evaporation-induced synthesis of monodisperse budded silica spheres Rapid evaporation-induced synthetic approach was used to fabricate budded silica spheres. The temperature of the sol-gel reaction and the following post-treatment were found to play crucial roles in determining the surface morphology of obtained silica spheres.6. One-step synthesis of functional chiral porous silica nanorods using a achiral surfactantUsing CTAB as surfactant, and organoalkoxysilane with functional group as the co-structure-directing agent, chiral porous silica nanorods were synthesized via an one-step process. The chiral nanorods could be used as a highly selective adsorbent for Hg2+ ions in wastewater.