Synthesis Of Metallic Oxide Nanostructures And Investigation Of Their Properties

Nanomaterials science is a discipline which has been extensively studied by scientists during the last twenty years. Nanomaterials is below 100 nm in size, with size effect, surface effect, quantum size effect, macroscopical quantum tunneling effect, and have extensive applications and potential value in optics, electrics, mechanics, magnetics, acoustics, and so on. Metal oxide nanomaterials have been a hot topic in recent years, which hold broad application prospect in photoelectricity, catalysis, gas sensor, magnetism, pollutant removal, lithium-ion battery, and so on. Howerver, the size, morphology, dimensionality, and so forth, have important impacts on such applications of metal oxide nanomaterials. In this dissertation, several metal oxide nanostructures were synthesized with different size, morphology, dimensionality by various preparation methods, and their properties and applications were also researched. The work mainly includes the following aspects:1. The synthesis and property of titanium oxide-based nanostructures(1) H2Ti3O7 nanotubes and Na2Ti3O7 nanowires were synthesized through hydrothermal method, and the morphology, crystalline phase, chemical component were analyzed by XRD, SEM and TEM. UV-vis absorption, photocatalysis, photoluminescence and TG-DTA experiments showed that the nanotubes had better optical properties and higher photocatalysis efficiency, whereas the nanowires had stronger fluorescence-emission and better thermal stability. Electrochemical cyclic voltammetry curves revealed that the nanotubes and nanowires could electro-catalyze cysteine, but could not electro-catalyze H2O2 in the voltage range of 0-1.0v. Moreover, by adding transition metal ions (Zn2+, Co2+) into primary hydro-thermal reaction solution, nanotubes were doped with zinc and Cobalt. And Uv-vis absorption test showed that the light absorption ranges of titanic acid nanotubes were broadened in a certain extent after doping transition metals, from ultraviolet region to visible region or infraredlight region.(2) Through a synthetic method at low temperature and atmospheric pressure, namely composite-hydroxide-mediated method (CHM), multilayer TiO2(B) nanosheets were synthesized. Post-treatments of the multilayer TiO2(B) nanosheets were also carried out:multilayer TiO2(B) nanosheets changed into quadrate TiO2(B) grains after calcining for 2h at 450℃; multilayer TiO2(B) nanosheets turned into anatase titania nanosheets after hydrothermal treatment for 3 days at 130℃. For the three samples, the transformations of the morphology, size, structural component and crystalline phase were characterized and compared by XRD, SEM and TEM. The crystal structures and surface absorptions were observed and studied by FT-IR and Raman tests, and thermal stability was mensurated and contrasted by TG-DTA: multilayer TiO2(B) nanosheets held change of the morphology over 400℃, quadrate TiO2(B) grains got better thermal stability after calcining for 2h at 450℃, anatase titania nanosheets maybe had transformation of crystalline phase above 650℃. Then multilayer TiO2(B) nanosheets have definite effect in removal of Cr(VI), and anatase titania nanosheets have preferable optical properties such as light absorption and photocatalysis.2. The synthesis and property of cerium oxide nanostructuresCeO2 nanospheres were synthesized through simple solvothermal method, high resolution TEM shows the as-prepared CeO2 consists of plenty of highly aggregated spheres of 3-5 nm, and is porous as a result of interspace between aggregated spheres. Porous CeO2 nanospheres have nicer optical performance in UV-vis light absorption with a optical band of 2.70 ev, which is smaller than that of the bulk CeO2(3.19 ev); they exhibited red and blue PL emission, and photocatalysis degrading efficency of 44.55% of 50 mg/L methyl orange. Porous CeO2 nanospheres showed predominant adsorbability in the removals of Cr(VI) and RhB in simulated waste water, and the adsorbent efficiency reached over 94% and 85%, respectively. Moreover, electrochemical experiments revealed that the porous CeO2 nanospheres could electro-catalyze cysteine but could not electro-catalyze H2O2 in the voltage range of 0-1.0 v.3. The synthesis and property of cupric oxide nanostructuresThrough nonaqueous synthetic method in low temperature and atmospheric pressure, namely composite-hydroxide-mediated method, flowerlike cupric oxide were synthesized with aquiferous cupric nitrate as raw materials after reacting for 24 h under 200℃. Cupric oxide nanostructures look like blooms composed of stromatolithic leafages which are acuate on two sides and wide in the middle with a thickness of below 50 nm, a width of 200-500 nm and a length of 2μm. The leaf surfaces is harsh because of some particulates on the surfaces. Optical experiments proved that the flowerlike cupric oxides have light absorption in infrared region. The cupric oxide undergoed a slow chemical process during adsorbing RhB in waste water, with an adsorbent efficiency of 53%.