Synthesis, Characterization And Property Study Of Several Functional Micro/nano Materials Based On Glucose

Manipulated synthesis of nanostructures is one of the hot areas in nanoscience and nanotechnology, and also the base and precondition to investigate distinctive properties and applications of nanostructural materials. Spherical hollow structures materials possess low densities, high surface areas, high stability, thermal insulativity, surface permeability and unique optical properties, all of which make them attractive for many applications. For instance, they might be used for catalyst supports, biochemical reaction, drug delivery, lightweight materials, catalysts, energy storage, and gas sensors, disease diagnosis materials, and so on. Template method is the most effective way to fabrication the hollow structures. And the monodispersed carbonaceous microspheres based on glucose hydrothermal reaction are ideal templates for the formation of hollow spheres because of hydrophilicity and containing a large amount of OH and C= O groups, the removal of carbon cores via calcination at low temperature, the synthesis no polluted.This thesis focuses on the preparation of several functional materials, including hollow LaCoO3 spheres, hollow La2O2CO3spheres, Ag@ CeO2 rattle structures, with glucose as the starting materials, through template techonology. The obtained products were characterized by scanning electron microscopy (SEM), the electronic transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetic (TG), Ultraviolet-visible (UV-vis), infrared spectroscopy (FT-IR) and Fluorescence spectrometry (PL). The photocatalytic activity of part products was studied. The main results are summarized as follows:1. Preparation, characterization and photocatalytic activity of hollow LaCoO3 spheresLaCoO3 hollow spheres have been prepared with the glucose-based carbon spheres as template through surface absorption. Firstly, hydrophilic carbon microspheres could bind La3+ and Co2+ into their hydrophilic shell and formed LaCo/C composite microspheres. Then, the sequential removal of carbon core via calcination resulted in the formation of LaCoO3 hollow spheres. By TEM and XRD analysis, it was found that the almost purity phase LaCoO3 hollow spheres with diameters about 80 nm, and the shell thickness about 5nm. We also studied the effect of calcination temperature and time for the crystal phase and morphology of the final products. In addition, by photodegradating methylene blue under sun light, it was found that LaCoO3 hollow spheres had a high photocatalytic activity.2. Preparation, characterization and Optical Properties of Hollow La2O2CO3 MicrospheresLanthanum oxycarbonate (La2O2CO3) hollow microspheres with novel cage-like architectures were successfully fabricated by a simple glucose catalytic polymerization-surface cation sorption one-pot hydrothermal treatment of an aqueous solution containing glucose, Lanthanum nitrate hexahydrate [La(NO3)3·6H2O], and subsequent calcination at 500℃for 4h. The experiment results indicate that the crystalline phases, crystallite size are much related to calcination temperature. Calcinated at 700℃for 4h, the products decompose mostly from La2O2CO3 to La2O3 phase. The results also revealed that the additive Co(NO3)2·6H2O exerted effects on the crystalline phases of the final product. Interestingly, the La2O2CO3 hollow spheres show a green emission band under UV excitation.3. Preparation of Ag@ CeO2 rattle structuresCoupling the reduction of noble metal salts and carbonization of glucose through hydrothermal treatment of an aqueous solution containing glucose and Ag(NO3)3, Ag@C core/shell structures were synthesized. Using these Ag@C core/shells structures as template, by chemical deposition method, precursor Ce3+ were first precipitated on the template surface in the form of CeOHCO3 and hydroxide through controlled hydrolysis under basic conditions. Then, the sequential removal of carbon core by calcination in air resulted in the formation of Ag@ CeO2 rattle structures. The obtained products were characterized by SEM, TEM, XRD and UV-vis. The experiment results indicated that as-prepared products were Ag@ CeO2 rattle structures with hexagonal Ag nanoparticles inside and cubic CeO2 outside. The samples were relatively uniform and exhibited diameters of around 200nm with the thickness of the shell around 20nm, and the core was around 100nm. And the samples showed UV-vis absorption of both Ag and CeO2. 4. Preparation of bifunctional Fe3O4@C@Ag materialsIn addition, magnetic-optical bifunctional Fe3O4@C@Ag materials were also successfully fabricated by post-capped route and ion-absorbed-reduced method. First, monodispersed Fe3O4 microspheres were capped with carbon shell through hydrothermal treatment of glucose, and resulted in Fe3O4@C core-shell microspheres. Then, Fe3O4@C core-shell microspheres were dispersed in AgNO3 solution with the aid of ultrasonication, Ag+ were absorbed and reduced to Ag on the carbon shell. The obtained products were characterized by TEM, XRD, IR and UV-vis. The results indicated that the Ag nanoparticles decorating the Fe3O4@C core-shell microspheres were about 40nm, and the samples showed good optical properties and magnetism.