Preparation of Porous Titania Film by Modified Sol-Gel Method and its Application to Photocatalyst

Sol-Gel derived mesoporous titania films with controlled pore sizes were prepared by surfactant templating. The coating sol was obtained by hydrolysis of Ti(OC₄H₉)₄ in ethanol/HCl solution. The gel films, prepared by spin coating on glass substrate, were dried after immersion in surfactant solutions under an atmospheric pressure. The porous films of anatase with columnar and rectangular structure were obtained after annealing at 500°C. The annealed films are transparent and 80–140 nm in thickness. Refractive indices of the films with surfactant immersion were 10–20% lower than those of the films without immersion. The spacing between the columns or rectangular grains and the grain shape were found to depend on the surfactant species. The pohoto-catalytic activity of the films for the oxidation of NO_x was improved by the surfactant modification.