| Nanomaterials show some unique properties that bulk materials do not have, such as quantum-size, surface and macroscopic tunnel effects. When the particle size is on the nanoscale, electric, magnetic, optical, thermodynamic, and mechanical properties change as a function of the size of the particle. These special physical and chemical properties endow them wide potential applications in many fields, such as electronics, chemistry, chemical engineering, life science and so on. However, the properties of nanomaterials are relevant with their size, shape and structure which make it important to research into the relationship between the structure and property in the field of fundamental research and practical application. The main contents of this thesis are summarized as follows:1. Flower-like Bi2MoO6 microstructures:solvothermal synthesis and visible-light-driven photocatalytic activitiesThe flower-like Bi2MoO6 microstructures have been prepared via a facile solvothermal approach, employing ethylene glycol as the reaction medium in the presence of ethylenediamine. Comparisions of three Bi2MoO6 microstructures with different morphologies suggest that the morphologies of the products have a great effect on the photocatalytic activities and the hierarchical flower-like Bi2MoO6 were found to exhibit best visible-light driven photocatalytic activities for the degradation of rhodamine B (RhB).2. Microwave-assisted synthesis and photocatalytic properties of flower-like Bi2WO6 and Bi2O3-Bi2WO6 compositeFlower-like Bi2W06 and Bi2O3-Bi2WO6 composite microstructures have been synthesized via a facile and rapid microwave-assisted hydrothermal method through controlling the experimental parameters. Photocatalytic experiments indicate that such Bi2O3-Bi2WO6 composite possesses higher photocatalytic activity for RhB degradation under visible light irradiation in comparison to pure Bi2O3 and Bi2WO6.3. Preparation and photocatalytic property of Ag-loaded Bi2GeO5 nanoflakesBi2GeO5 nanoflakes have been successfully prepared via a simple, rapid microwave-assisted hydrothermal process. Ag nanoparticles have subsequently been deposited on the Bi2GeO5 nanoflakes by facile photoreduction. Catalytic activity of the Ag/Bi2GeO5 nanocomposite in the photo-degradation of rhodamine B (RhB) is much higher than that of pure Bi2GeO5. The amount of Ag in the nanocomposite affects the catalytic activity, and 3 wt% Ag showed the highest photodegradation efficiency.4. Microwave-assisted hydrothermal synthesis and characterization of flower-like Bi4Ge3O12 microstructuresFlower-like Bi4Ge3O12 microstructures have been successfully prepared via a simple, rapid microwave-assisted hydrothermal process. Some control experiments have been carried out to reveal the influencing factors involved in the formation, which suggested that reaction time, reaction temperature, the volume of ammonia and glycerol play crucial roles in the formation of the flower-like Bi4Ge3O12. The optical absorption property of the product has also been investigated.5. Microwave-assisted hydrothermal synthesis and characterization of flower-like PbGeO3 microstructuresFlower-like PbGeO3 microstructures were successfully synthesized via a facile and rapid microwave-assisted hydrothermal process. Experimental results revealed that the entire structure of the architecture is composed of a large quantity of individual nanorods. The optical absorption property of the product has also been investigated.6. Synthesis and magnetic properties of various sized CuGeO3 nanorodsMagnetoelastic coupling refers to the spin-lattice interactions that take place in magnetic solids.CuGeO3 is a quasi-one-dimensional S=1/2 antiferromagnet that has attracted attention as the first inorganic material to display a spin-Peierls transition (SP). SP transition, a magnetoelastic process driven by the combination of spin singlet formation and lattice distortion, appears at 14 K in single crystals of CuGeO3. Recent measurements have revealed that magnetoelastic coupling may be sensitive to finite length scale effects, although it is not yet clear how confinement manifests itself in CuGeO3 or on the SP mechanism in general. In this study, we find that the SP transition in crystalline CuGeO3 nanorods (ca.<600 nm length) is quenched, demonstrating that the magnetoelastic coupling is blocked in the small nanorods. By contrast, longer CuGeO3 nanorods (-600 nm->2 ?m length) show a weak SP transition. These findings demonstrate that size is an effective tuning parameter for controlling the ground state properties of CuGeO3 and other magnetic materials where spin-lattice interactions are important.7. Microwave-assisted hydrothermal synthesis and photocatalytic property of cube-like Ag-Ag2MoO4Cube-like Ag-Ag2MoO4 composite has been successfully prepared in the presence of PVP (polyvinylpyrrolidone) via a facile microwave-assisted hydrothermal process. Studies of its photocatalytic performance in the decomposition of RhB indicate that the cube-like Ag-Ag2MoO4 composite exhibits good catalytic activities under visible light irradiation. The presence of Ag promoting the absorption of visible light may be attributed to the surface plasmon resonance. Reaction temperature, reaction time and the amount of PVP have also been studied and found to play crucial roles in the formation of the cube-like microstructures.8. Microwave-assisted hydrothermal synthesis and photocatalytic property of pancake-like Cd(OH)2 superstructuresPancake-like Cd(OH)2 superstructures were prepared via a facile and rapid microwave-assisted hydrothermal method, employing cadmium acetate and hydrazine hydrate as starting materials in the mixed medium of water and glycerol. Several influencing factors, such as the volume of hydrazine hydrate and glycerol, reaction time, temperature and cadmium source, were found to play important roles in the formation of the Cd(OH)2 multilayer stacked structures. The as-obtained Cd(OH)2 superstructures show an enhanced photocatalytic activity for the decomposition of rhodamine B (RhB) under basic condition. |
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