Charged Nanowires Directed The Growth Of Inorganic Nanomaterials And Its Properties

Recently, biominerals in various organism has received much attention not only for its hierarchical structures but also for its predominant properties. Based on the mechanism underlying biomineralization process how to synthesize new advanced functional materials with excellent properties have been one of the most important challenges in chemical and material science. Furthermore, one-dimensional nanostructures are analogous to bio-macromolecule or assembly aggregates of supermolecules in organism that can induce the growth of biominerals because of many charges or functional groups existed on the surface of nanowires. According to the discussion above, the present dissertation will focus on how the control the growth of biominerals or advanced functional materials under the inducing of charged inorganic nanowires. The main results can be summarized as followed.1.A synthesis system that using ultrathin inorganic nanowires as inducer to direct the growth and assembly of amorphous calcium carbonate (ACC) have been successfullybuilt to produce ACC@Te nanowires and ACC nanotablets. In such system, Te nanowires stabilized by polyvinyl pyrrolidone (PVP) were used as inducer to direct the assembly of ACC nanoparticles by gas diffusion or solvothermal based method. Remarkably, charges on the surface of nanowires are crucial for forming ACC@Te nanowires and ACC nanotables with uniform size.The role of the concentration of Te nanowires, mixed solvent and the diameter of Te nanowires is discussed deeply to draw conclusion on how ACC assembly around Te NWs to form ACC@Te nanowires and ACC nanotablets.Furthermore,using ACC nanostables as building blocks and sodium alginate as glues, freestanding ACC films with remarkabletoughness have been produced. Additionally, functional magnetic nanoparticles can be loaded on the ACC nanotables because of the existence of PVP molecules on the surface of ACC nanotables.The synthesis reported here can be applied to the assembly of other carbonate salt nanostructures systems and can give some useful clues for comprehensive understanding the mechanism of biomineralization.2. Developing a general strategy to produce amorphous metal hydroxide nanofibers by using xonotlite nanowires as inducer. Applying such a simple method, amorphous bimetal hydroxide nanofibers have been synthesized. Moreover, metal oxide nanofibers can be obtained by the treatment of metal hydroxide mentioned above. Such strategy can also been applied to synthesize other metal hydroxide and the metal hydroxide synthesized by such method have many potential applications including electrical catalysis and energy storage.3. Establishing a new strategy to prepare hematite microsphere mesocrystals by a simple hydrothermal process under the directing of xonotlite nanowires. Nanowires as templates were mixed with ferric chloride and the reaction system was heated to 160 degree centigrade. In such process, the primary crystal building blocks would form and assembly into mesocrystals. Finally, uniformhighly crystallized hematite mesocrystals can be obtained. In such biomineralization system, the morphology and size of the products can be tuned by the concentration of xonotlite nanowires and ferric chloride respectively. Moreover, we have discussed the forming mechanism of hematite mesocrystals. This strategy features highly tuned, low-cost and high efficiency and establish a new avenue for obtaining new novel functional materials with hierarchical structures for various potential applications.4. We have further investigated an environmentally friendly and effective process for phase transformation of Mg-ACC in binary solvent of ethanol and water without adding any organic additives under mild conditions. By this strategy, the kinetic and thermodynamic control can be regulated by simply tuning the volume ratio of ethanol to water, the temperature and the concentration of Mg-ACC. Specially, aragonite microellipsoids constituted with aragonite nanofibers have been obtained after 24 h biomineralization in ethanol-water mixed solvent (the volume ratio of ethanol to water is 3/2) when the initial concentration of Mg-ACC is 4.5 mM. Such research can offer some useful clues for deep understanding the biomineralization process of calcium carbonate.