Titanium dioxide films made from reverse micelles and their use for the photocatalytic degradation of adsorbed dyes

Titanium dioxide mesoporous films have been deposited on glass slides by dip-coating in reverse micellar gels containing titanium isopropoxide. Reverse micelles were first made in cyclohexane, and the alkoxide was added last. Hydrolysis and inorganic polymerization produced composite organic/inorganic gels that were deposited on glass slides giving uniform transparent films. Calcination at 450 degrees C gave TiO2, nanoparticle mesoporous films. The films possessed a high capacity for adsorption of several different dyes from aqueous or alcoholic solutions. Illumination of the colored films by visible light led to a rapid degradation of the adsorbed dyes. The phenomenon is explained by a photosensitisation process involving the semiconductor and the adsorbed dye itself [N. Chouhaid, K. Vinodgopal, L. Fisher, S. Hotchandani, A.K. Chattopadhyay, P. Kamat, J. Phys. Chem. 100 (1996) 8436]. The differences between films made by varying some parameters are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.