Room temperature deposition of a TiO2 thin film from aqueous peroxotitanate solution

A transparent, high purity, amorphous titanium dioxide thin film composed of densely packed nanometer-sized grains has been successfully deposited on a glass substrate at room temperature from an aqueous peroxotitanate solution using a simple, inexpensive, reproducible, and environmentally friendly method. The as-deposited thin film was 117 nm thick and composed of closely packed particles of 10-15 nm in diameter, but they aggregated into large grains of 50-100 nm in diameter. The aqueous peroxotitanate solution was obtained by dissolving metatitanic acid (H2TiO3) in a mixture of concentrated H2O2 and NH3.H2O. An anatase TiO2 thin film was obtained by heating the as-deposited thin film at 500degreesC for 1 h in air. A chemical composition of TiO1.4(O-2)(0.5)(OH)(0.2).1.34H(2)O is proposed for the as-deposited thin film, based on XPS, FT-IR and TG-DTA data. Band gap energies of 3.20 eV for indirect transition and 3.63 eV for direct transition were obtained for the anatase TiO2 film.