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Cerium oxide, or ceria (CeOx: x = 1.5 to 2), has been widely used as a heterogeneous catalyst. Ceria has several properties make it high catalytic active: the fluctuating valence of cerium, the high oxygen storage capacity and high oxygen mobility in the nonstoichiometric ceria. With the high abundance of cerium on earth crust, ceria is a highly effective alternative of the noble metal catalysts. Research has been focused on designing nanostructured ceria and ceria related materials in recent years. The catalytic activity of ceria can be enhanced by the nanoscale effect which can be applied for various designs of catalysts with unique properties.
In this thesis, I report two types of ceria-based nanomaterials fabricated by the electrochemical and dispersion-precipitation methods and our study of their physical and chemical properties. First, I discuss the fabrication of a ceria nanoporous membrane using a two-step method of anodization and subsequent calcination. A proposed anodization model involving the oxygen bubbles generation during the process for the growth of the nanoporous membranes is discussed. Second, I illustrate a new type of ceria-titania hybrid nanocomposites for oxidative catalysis. A dispersion-precipitation synthetic method for these catalysts and the evaluation of their oxidative catalytic activity are presented. Finally, I discuss other potential synthetic methods to produce and further enhance the catalytic activity of these hybrid nanocomposite catalysts.
Supervisor: Chin Li Cheung