(799c) Ultra-Thin Porous Metal Oxide Films Prepared By Molecular Layer Deposition

Porous thin films/coatings have wide applications in separations, corrosion protective coatings, gas storage, controlled drug delivery, and catalyst encapsulation for controlling reaction selectivity and maintaining catalytic activity. Ultra-thin porous films/coatings are especially important for some applications. This paper demonstrates a general method to create porous metal oxide films with well-defined porous structures and precisely controlled thickness down to several angstroms from dense organic/inorganic hybrid metal alkoxide films grown by molecular layer deposition (MLD). The organic constituents in the film can be removed either by mild water etching at room temperature, or calcination in air at elevated temperatures. Because of the layer by layer growth process for MLD, the deposited polymer films have regular structure and the removal of MLD polymer films produces uniform interconnected highly porous structures with high surface area. Porous alumina and titania can be prepared by this method. For example, the porous alumina films have both micropores and mesopores with BET surface area as high as 1000 m²/g.