| New approaches to the synthesis of magnesium, aluminum and nickel oxides with three-dimensionally ordered macroporous (3DOM) structure by colloidal crystal templating were explored. Such metal oxides were characterized by powder X-ray diffraction, scanning and transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry and nitrogen gas adsorption. Interconnected macropores, either organized in periodic arrays or positioned randomly, varied in diameter from 275 to 950 nm. The effect of the pore size on sintering behavior of the material was studied on macroporous α-Al2O3. Having a free diffusion path inherent to 3DOM structure, such morphology offers the advantage of highly accessible surfaces, which makes it an interesting candidate for catalyst supports. A silver catalyst supported on 3DOM α-Al 2O3 was tested in epoxidation of ethylene and its performance was compared to that of the catalyst prepared on commercial alumina support. The procedure successfully used for the preparation of macroporous α-Al 2O3 was adopted for the synthesis of 3DOM lithium aluminates. Namely, a mixture of LiAl5O8 and γ-LiAlO 2, as well as pure β- and γ-LiAlO2 phases were obtained. Correlations between the manner in which the lithium precursor was introduced, the molar ratio between lithium and aluminum precursors, the heat treatment conditions and the morphology and phase composition of the product were established. With their open pore structures and thin walls, these materials may have potential applications as breeder materials for fusion reactors or as ceramic matrixes in molten carbonate fuel cells. As a part of a related project targeting a nano-assembled lithium solid state battery, proposed cathode material, LiCoO2, was obtained in a form of macroporous thin films prepared by electrostatic spray deposition on Pt-coated quartz substrates and electrochemical measurements were performed on these films. |
