Study On Chemical Synthesis Of Binary Transition-Metal Compound Hollow Structures

Owing to their unique physical properties, binary transition-metal compound micro/nanomaterials have exhibited promising applications in energy storage, sensing, catalysis, etc. Chemical synthesis of novel structures, investigation of formation mechanisms and control of crystallization sizes and dimensionalities are hot topics in this research area. These studies will promote the research work on investigation of the relationship between structures and properties, designed fabrication of materials, efficient utilization of micro/nanostructures and their industrialization. In this dissertation, systematic explorations have been carried out on new synthetic strategies of metal oxide and sulfide hollow structures, their formation mechanisms and electrochemical properties (e.g. energy storage and electrochemical sensing). The main points can be summarized as follows:With SnCl4 and vanadium (Ⅳ) acetylacetonate as the reactant, V2O5-SnO2 double-shelled nanocapsules were synthesized by a solvothermal treatment at 190-220℃and final heat treatment in air at 400-500℃. The formation mechanism of the current double-shelled nanocapsules is a combination of two types of Ostwald ripening (both inward and outward ripening cases). Anisotropic Co3O4 porous nanocapsules were also synthesized via this similar solvothermal route and final heat treatment in air. These hollow structured V2O5-SnO2 double-shelled nanocapsules and Co3O4 anisotropic nanocapsules are high-performance electrode materials for Li-ion batteries, which exhibit high reversible capacity and good cycle performance. These results indicate that these metal oxide nanocapsules are promising electrode candidates for Li-ion batteries.High-porosity hollow doughnut-shaped and spherical CuO structures were synthesized by thermal oxidation of the corresponding CuS and Cu2S precursors at 700-800℃, respectively. With CoS and NiS as precursors, the corresponding Co3O4 and NiO porous and hollow structures were achieved. The combination of non-equilibrium interdiffusion, volume loss, and gas release has been proposed to explain the formation of these porous hollow structures. SnO2 porous nanotubes and Sn@C one-dimensional nanocomposites were also obtained with one-dimensional SnS nanobelts as precursors. As anode materials for Li-ion batteries, the first discharge capacities of these SnO2 porous nanotubes and Sn@C one-dimensional nanocomposites are 910 and 1050 mAhg-1,respectively. CuS nanotubes with rectangular cross-section were rapidly synthesized at 75-85℃through a microwave-assisted chemical transformation route with Cu-complex nanowires (obtained at room temperature) as reaction precursors. The Cu-complex nanowires were facilely synthesized with different diameters, which can determine the diameter of final CuS nanotube products. The as-prepared CuS nanotube-modified electrode exhibits a detection limit of 0.25μmol L-1 and a sensitivity of 9.9μAμmol L-1 when applied as the electrochemical sensors for glucose.