Morphology metal oxide nanoparticles

The aerogel-prepared metal oxide nanoparticles constitute a new class of porous inorganic materials because of their unique morphological features such as crystal shape, pore structure, high pore volume, and surface areas. Also, it is possible to load catalytic metals such as Fe or Cu at very high dispersions on these oxide supports and hence the nanocrystalline oxide materials can also function as unusual catalyst supports. Furthermore, these oxides can be tailored for desired Lewis base/Lewis acid strengths by incorporation of thin layers of other oxide materials or by preparation of mixed metal oxides. 

Using a dynamic collection of droplets in a gas medium is also a well-known procedure to restrict the reaction volumes and obtain nanoparticulate materials by a thermally promoted reaction (spray pyrolysis]. Chidembo et al. [112] used an in situ spray pyrolysis approach to fabricate metal oxide-graphene composites with highly porous morphologies. The materials exhibited unique globular structures comprising metal oxide nanoparticles intercalated between graphene sheets. 

Besides the conducting polymer-based nanostructured materials, organic hybrid nanocomposites, especially chitosan and Nafion, metal/metal oxide nanoparticles are being explored for effective and efficient biosensor fabrication. Such hybrid nanocomposites show properties different from their parent constituent precursors and are dependent on concentration of precursors, their morphology, and novel interfacial characteristics. 

The fundamental goal of nanoparticle research is to assemble atoms in a controllable way and design nanostructured materials with the desired physical and chemical properties. A major part of the research in the field of nanoscience is dedicated to the development of synthesis routes to nanoparticles and nanostructures. Conventionally, solid-state reactions between powders have successfully been employed for the low-cost production of bulk metal oxides. However, to obtain metal oxide nanoparticles with well-defined shape, size, and composition, these solid-state routes are unsuitable. In contrast to these high-temperature processes, liquid-phase synthesis routes, and in particular sol-gel routes, offer better possibility to control the variation of structural, compositional, and morphological features of the final nanomaterials [1,2]. 

Within this project, experimental results and theoretical models were combined to describe and predict the stabilization of metal oxide nanoparticles using small molecules. For the synthesis of well-defined highly crystalline metal oxide nanoparticles as model systems, the non-aqueous sol-gel synthesis was employed. This synthesis is an easily reproducible method that enables the control of the particle size as well as the morphology of the particles. To describe and model the stabilization with short molecules, such as amines or carboxylic acids, ITO and Zr02 nanoparticles were selected as model systems. To prevent influences of the in situ stabilization... 

The main focus of the project was the elucidation of particle-stabilizer-solvent interactions as a function of the binding strength, the chain length, the concentration of the stabilizers, the polarity of the solvents, and the surface configuration as well as the size and morphology of the metal oxide nanoparticles. Therefore, to characterize the stabilization kinetics, a number of analytical methods, such as thermogravimetric analysis, isothermal titration calorimetry, and spectroscopic methods, were combined. 

It was also found that the presence of some metal ions and borates can effectively accelerate the hydrothermal carbonization of starch, which shortens the reaction time to some hours. Thus, iron ions and iron oxide nanoparticles were shown to effectively catalyze the hydrothermal carbonization of starch (< 200 °C) and also had a significant influence on the morphology of the formed carbon nanomaterials [10]. In the presence of Fe2+ ions, both hollow and massive carbon microspheres could be obtained. In contrast, the presence of Fe203 nanoparticles leads to very fine, rope-like carbon nanostructures, reminding one of disordered carbon nanotubes. 

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