Visible-light-driven photocatalytic activity of kaolinite: Sensitized by in situ growth of Cu-TiO2

Sensitized kaolinite with improved visible-light catalytic activity was prepared via a facile in-situ growth of nanosized Cu-TiO 2 on the surface of the sulfated kaolinite impregnated in Cu-TiO 2 sol. The as-prepared photocatalysts were characterized in terms of various techniques. The transmission electron microscope and energy dispersive spectrometer results revealed that Cu-TiO 2 could grow on the surface of the pretreated kaolinite and the aggregation of Cu-TiO 2 was successfully inhibited. The X-ray photoelectron spectrum confirmed the formation of Al  O  Ti bonds between Cu-TiO 2 and sulfated kaolinite in the sensitized kaolinite composite. The sensitized kaolinite composite exhibited significantly improved performance in the degradation of Rhodamine B (RhB), leading to about 87% of RhB degradation in 180 min, which is superior to that of the kaolinite, calcined kaolin, and sulfated calcined kaolin under visible-light irradiation. The superior photodegradation activity of the sensitized kaolinite composite was primarily attributed to the synergetic effect of Cu-TiO 2 sensitization and sulfation, resulting from the efficient transfer and separation of the photo-induced charge carriers between Cu-TiO 2 and kaolinite.