The Fabrication And Application Of Inorganic Hollow Micro/Nano Structure

The goal of this dissertation is to explore facile chemistry principle and approach to synthesize inorganic hollow nano/micro materials and study the application of these materials. This dissertation develops a new route to systematically fabricate MoS2 hierarchical hollow cages with various well-defined, novel geometrical morphologies. Electrochemical hydrogen storage properties of these materials are also investigated. This dissertation also studies the scaling properties in transistors that use aligned arrays of single walled carbon nanotubes produced by CVD. Theoretical and experimental studies of Schottky diodes that use aligned arrays of single walled carbon nanotubes are present too. The details are summarized briefly as follows:1. Micrometer scaled MoS2 hierarchical hollow cubic cages assembled by bilayers can be synthesized via a one-step selfassembly coupled with intermediate crystal templating process without any surfactant, in which the intermediate K2NaMoO3F3 crystal formed in-situ and then served as the self-sacrificed template based on the Kirkendall Effect; The MoS2 hierarchical hollow cubic cages were employed for electrochemical hydrogen storage with a high capacity of 375 mAh g-1 due to the more active edges exposing on the upright-standing nanoplates.2. We proposed a general route to MoS2 hierarchical hollow cages, in which abundant hollow cages with various well-defined, novel geometrical morphologies were fabricated via a self-assembly coupled with surfactant/molybdate composite precursor crystal templating process based on the Kirkendall Effect. The in situ formed surfactant/molybdate composite precursor crystals with cubic structures, which are cooperatively assembled by periodic Mo oxo anion and tetrabutylammonium cation, play crucial roles as both the Mo source and the template in the formation of MoS2 hierarchical hollow cages. Various morphologies of the surfactant/molybdate composite precursor crystals were controllably synthesized through a methodical tuning of the habit and the degree of branching of precursor crystals by varying the SCN- concentration and surfactant concentration.3. We systematically study the scaling properties in transistors that use aligned arrays of single walled carbon nanotubes produced by CVD, present the results of systematic investigations of the dependence of device properties on channel length, to reveal the role of channel and contact resistance in the operation. The results indicate that, for the range of channel lengths and SWNT diameters studied here, source and drain contacts of Pd yield transistors with effectively ohmic contacts that exhibit negligible dependence of their resistances on gate voltage. For devices that use Au, modulation of the resistance of the contacts represents a significant contribution to the response. Extracted values of the mobilities of the semiconducting SWNTs and the contact resistances associated with metallic and semiconducting SWNTs are consistent with previous reports on single tube test structures.4. We present theoretical and experimental studies of Schottky diodes that use aligned arrays of single walled carbon nanotubes. A simple physical model, taking into account the basic physics of current rectification, can adequately describe the single-tube and array devices. We show that for as grown array diodes, the rectification ratio, defined by the maximum-to-minimum-current-ratio, is low due to the presence of m-SWNT shunts. These tubes can be eliminated in a single voltage sweep resulting in a high rectification array device. Further analysis also shows that the channel resistance, and not the intrinsic nanotube diode properties, limits the rectification in devices with channel length up to ten micrometer.