Synthesis Of Hierarchical And Hollow Micro/Nanostructures Of Transitional Metal Compounds And Their Properties

The objective of this dissertation is to explore the facile, mild, easily-controlled synthesis of transition metal compounds hierarchical and hollow micro-/nanostructures in solution by hydrothermal route via complex precursor method, which developing the effective methodology to control both the phase and morphology of the final products. Moreover, morphologies on their properties have also been investigated. The main points are summarized as follows:1. We report a low-temperature hydrothermal route without a preformed template to prepare Cu2O crystallites with controlled morphologies, including porous hollow microspheres, octahedral microcages and microcrystals with truncated corners and edges and octahedral microcrystals. To the best of our knowledge, this is the fist time for the one-step solution-based synthesis of novel octahedral microcages with truncated corners and edges. In particular, a process mechanism has been revealed for the growth of these kinds of Cu2O microcrystals. Cu2O microparticles, whose photocorrosion rate is very slow, have a higher photocatalytic activity than Cu2O nanoparticles, although Cu2O microparticles have much lower adsorption capacity than Cu2O nanoparticles. As a result, the photocatalytic properties of the Cu2O microcrystals are also presented.2. Various3D MnV2O6nanostructures, including pompon-like MnV2O6spheres, nanobundles and hierarchical urchin-like MnV2O6spheres with oxygen-containing surface groups, have been prepared using a simple two-step procedure, involving the preparation of vanadyl ethylene glycolate (VEG) as the precursor. A process mechanism has been revealed for the self-assembly of the3D architectures of MnV2O6. In particular, as an example of potential applications, the as-obtained3D architectures of MnV2O6with surface functionalization were used as adsorbent in waste-water treatment, which showed better performance to remove various water pollutants.3. We have demonstrated a simple chemical route to the large-scale synthesis of low-valent VO2(A) nanostructures. The difference in the concentration of carboxyacetic acid and temperature can be easily used to control the crystal morphology, such as flower-like V02(A) microspheres, cactus-like VO2(A) microcrystals, micrometer-sized V02(A) arrays, and VO2(A) nanorods. Carboxyacetic acid, as a structure directing agent, play a very important role in an alternative preparation of the VO2(A), which may be of much significance in the alternative synthesis of other Low-valent vanadium oxide. Furthermore, electrochemical behaviour of the as-prepared VO2(A) have been reported. VO2(A) nanorods deliver a higher capacity to store charge than the other structure V02(A) cycled under the same conditions, which mainly depends on the crystallinity and size.4. Pure phase V02(A) have been synthesized via a facile hydrothermal method by hydrolysis of vanadyl ethylene glycolate in carboxyacetic acid solution. Furthermore, the doping of molybdenum in VO2(A) was carried out tentatively for the first time on the best of our knowledge. The doping of molybdenum led to the destabilization of V02(A) phase. Based on our experiment, with doping of molybdenum, VO2(A) nanorods transformed to VO2(B), and then the star-like V02(R) was obtained. the doping of molybdenum could decrease phase transition temperature and the hysteresis of this phase transition was confirmed by DSC measurement.