Synthesis, characterization and visible-light photocatalytic activity of TiO2–SiO2 composite modified with zinc porphyrins

Three types of silica gel supported titanium dioxide particles immobilizing Zn(II) carboxylphenyl porphyrins appending p-CH 3 , p-H and p-Cl phenyl substituents (designated as ZnMP–TiO 2 –SiO 2 , ZnPP–TiO 2 –SiO 2 and ZnCP–TiO 2 –SiO 2 , respectively) have been synthesized and characterized using SEM, XRD, IR, AFS, DRS, UV–Vis, XPS and TG. The photodegradation of α -terpinene in aqueous suspension was used to determine the photocatalytic activity of TiO 2 –SiO 2 samples which had been impregnated with Zn(II) porphyrins, as sensitizers. The experimental results confirmed that the photocatalytic activitys of these composites are much higher than those of the nonmodified TiO 2 –SiO 2 under visible light irradiation and follow the order of ZnMP–TiO 2 –SiO 2 > ZnPP–TiO 2 –SiO 2 > ZnCP–TiO 2 –SiO 2 .