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Cluster-Assembly-Directed Synthesis of Ultrathin Nanostructures at All Scales

Author: HuShi
Tutor: WangXun
School: Tsinghua University
Course: Chemistry
Keywords: single-walled nanotube inorganic fullerene ultrathin nanowire ultrathin nanoroll ultrathin nanobelt
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Type: PhD thesis
Year: 2012
Downloads: 197
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Abstract


Research in ultrathin nanostructure has emerged as a hot topic, due tospecial changes in its atomic arrangement, electronic structure, magnetic,electro-chemical and carrier transport properties. Fabrication of ultrathinnanostructure requires a deep understanding and further innovation beyondcurrent knowledge of inorganic nanomaterials. With a distinct structure andenergy diagram at the ultrathin dimension, cluster assembly and growth couldoccur, leading to possible novel nanostructures and properties. In this regard,the fabricating of new nanostructure from cluster-assembly routes bears greatsignificance.From this point, we have developed a series of ultrathin nanostructure froma few different systems, characterized their properties and analysed theformation mechanism behind the growth, hoping to establish a cornerstone forfuture discovery and application of new nanostructures.（1）.Our first work focused on the water-thiol interface assembly of aqueouspolyoxometalate ions, which facilitates the formation of MoO3single-wallednanotubes.（2）.Inorganic fullerne like structure takes a high curvature and its synthesisrequires harsh conditions with the yield and dispersibiliity usually poor. Here,an alcothermal reaction with oleic acid and oleylamine brings about oil-soluablefullerene-like colloid of nickel chlorohydroxide with a high yield. Timeevolution of product provides evidence for a mechasnism involving the"nucleation-assembly-growth-recrystallization" of small clusters.（3）.Similar system involving the hydrolysis/alcoholysis of of GdCl3giveslong ultra-thin nanowires of GdOOH with polymeric similarity and theirassembly in organic solvent is remarkable, with great variatiy intwo-dimensional pattern under Transimission electron microscopy andshear-thinning in rheological measurement. （4）.Ultrathin nanoroll of Y（OH）3fabricated with similar method displayeda counter-intuitive decoiling behavior while its high-aspect-ratio counterpartscoil from films. Furthermore, when the aspect ratio is low, nanobelt halfextended to form interesting structure including spirals. On the other hand,MoO3also forms such nanorolls provided with a interface between acidifiedmolybdate solution and oleylamine and change of the interface withcyclohexane gives out large-area ultrahin nanofilm ultrathin nanoribbons andnanoparticles of Uranium oxide（5）.Uranium Oxide contains a wide spectrum of semiconductors yet littleexplored outside the nuclear application. A controlled thermolysis method wasdeveloped to controll the growth of ultrathin nanoribbon of U3O8andsperical/multipod UO2nanoparticles and these may lead to more development inthe uranium nanochemistry.

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