2006 AIChE Annual Meeting
(512e) Synthesis and Crystallization of Titania Films with Orthogonally Aligned Hexagonal Close Packed Cylindrical Nanopores
Non-interconnected 2D hexagonally close packed (HCP) cylindrical channels would be ideal pores for many applications because of the non-tortuous, non-intersecting path that they would offer for transport of gases, solvents, solutes, and electrons. However, the cylindrical nanopores of HCP films usually align parallel to the substrate surface because of preferential interactions between the substrate surface and the surfactant molecules. This orientation makes the pores mostly inaccessible. We have developed a straightforward method of aligned cylindrical pores in HCP silica films normal to the substrate by dip coating the films onto chemically neutral substrates. Here we extend this idea to create crystalline titania films with orthogonally oriented HCP cylindrical mesopores. Titania presents the additional challenge that crystallization, if not carefully controlled, can destroy the long range pore order introduced by the surfactant template. Controlling processing factors like humidity, curing time, and calcination temperature allows us to preserve orthogonally oriented HCP pores in crystalline titania films. Titania films with orthogonally aligned HCP nanopores have an ideal structure for organic-inorganic hybrid photovoltaics.