Transition metal nanoparticles are of considerable interest as heterogeneous catalysts in numerous industrial processes. Recently, mesoporous silica materials have attracted much attention as excellent supports of bifunctional catalysts with high surface area. Bifunctional structures combining active metal particles and metal oxide supports are known to be the most effective form of heterogeneous catalysts owing to their high stability and multiple functionalities. Rational design of the bifunctional catalyst structures using nanosynthetic technology can improve reaction performances including activity, selectivity, thermal stability, and recyclability.
In chapter I, we introduce unique features of the metal nanoparticles as good heterogeneous catalysts and the importance of controlling nanostructures for catalytic reactions. In chapter 2, we report gram scale synthesis of uniform $Cu_2O$ nanocubes and their subsequent transformation to polycrystalline CuO hollow nanostructures. These CuO nanostructures are used as lithium ion battery anode materials and are applied to organic catalytic reactions as good heterogeneous catalysts. In chapter 3, we introduce various metal@silica yolk-shell nanoreactor frameworks which consist of metal cores inside hollow silica shells for various gas- and solution-phase catalytic reactions. In chapter 4, we report hybridization of bifunctional elements by solution-phase chemical reactions. The final nanostructures are successfully employed as active nanocatalysts for organic catalytic reactions with excellent activity and recyclability.