Rational design of efficient visible-light driven photocatalyst through 0D/2D structural assembly: Natural kaolinite supported monodispersed TiO2 with carbon regulation

In this work, kaolinite supported monodispersed TiO2 with carbon regulation was prepared through rational design and different dimensions' assembly, leading to generation of Ti-III species in carbon doped TiO2/kaolinite (C-TiO2/kaolinite) composite. The C-TiO2/kaolinite composite exhibited improved degradation performance towards ciprofloxacin under visible light, with a reaction rate constant of 0.00597 min(-1), which is about 3.24 and 24.88 times higher than that of 2.0C-T (2.0% carbon-doped TiO2) and pure TiO2, respectively. Based on various materials characterization methods and DFT calculations, it was indicated that the electronic structure was correlated with the changes in light absorption, charge carrier lifetime, and reactive oxygen species (ROS). The enhanced visible light responding ability could be attributed to the synergistic effect between natural kaolinite and nanosized TiO2, the formation of localized occupied states in the gap, and the formation of TiIII defects consisted of surface oxygen vacancies. All of them effectively increase the separation efficiency, migration velocity, and lifetime of the photoinduced charge carriers under visible-light irradiation. Overall, our study provides a promising candidate for effective degradation of trace amounts of pharmaceutical and personal care products and other highly toxic contaminants with the assistance of solar light.