Acrylate photopolymerization on heterostructured TiO2 photocatalysts

Heterostructured TiO2 samples were prepared by precipitation of Al2O3, Fe2O3 hydrate, AgCl and Ag2O, respectively, onto the surface of a commercial anatase type pigment. The photopolymerization of an ethoxylated trisacrylate was used as a test reaction to check the photocatalytic activity of the heterostructured TiO2 samples. The TiO2 sample coated with Al2O3 showed no noticeable photocatalytic activity; the untreated TiO2 was also not a good photocatalyst; in contrast, the TiO2 samples which had been coated with Fe2O3 or AgCl showed enhanced polymerization rate as well as monomer conversion after 120 s illumination. The results of the photopolymerization experiments are explained on the basis of the thermodynamics of the charge transfer between the photoexcited TiO2 samples and the acrylate. The photoelectric properties of the TiO2 samples which were characterized using transient Photo-EMF measurements also play an important role in their photocatalytic activity.