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 t echnique 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 glas s surface was effective in preparing a uniform film because of hydrophobici ty of the complex melt. The resultant film was transparent and composed of anatase after heating at 500 degreesC. Micrometer-scale rough surface with aggregates of secondary particles composed of primary crystallites was obse rved in the film, and mesopores seem to be located at the inter-crystallite s. It is probable that decomposition of stearic acid and aggregation of ana tase crystallites occur simultaneously to provide the porous structure duri ng heating.