Preparation of Porous Titania Film from Precursor Solution Containing Titanium Alkoxide and Stearic Acid

A porous titania film was prepared on a glass substrate by a spin-coating technique from the precursor solution containing titanium tetraisopropoxide and stearic acid. Stearic acid formed a 2:2 complex with titanium in the dried film, and the complex melted before decomposition. Before the coating of the precursor solution, methylsilane precoating on the hydrophilic glass surface was effective in preparing a uniform film because of hydrophobicity of the complex melt. The resultant film was transparent and composed of anatase after heating at 500°C. Micrometer-scale rough surface with aggregates of secondary particles composed of primary crystallites was observed in the film, and mesopores seem to be located at the inter-crystallites. It is probable that decomposition of stearic acid and aggregation of anatase crystallites occur simultaneously to provide the porous structure during heating.