Effect of thickness and microstructure of TiO2 shell on photocatalytic performance of magnetic separable Fe3O4/SiO2/mTiO2 core-shell composites

Here, unique Fe3O4/SiO2/mTiO(2) (FST) composites were fabricated, which are composed of a Fe3O4 core with a strong response to magnetic field, an intermediate SiO2 layer as an electronic barrier, and an outer mesoporous TiO2 (mTiO(2)) as the active layer for degradation of organic contaminants. The distinctive approach involved TiO2 shell coating on the surface of Fe3O4/SiO2 (FS) particle using a sol-gel method, followed by the crystallization and mesopore-formation of TiO2 through solvothermal treatment. By changing the dosage of tetrabutyl titanate (TBOT), the thickness and microstructure of TiO2 layer were regulated. Among all as-prepared FST composites, the FST composite that was prepared with 0.6ml TBOT (FST-0.6) possessed a good microstructure and a large specific surface area, and exhibited superior photocatalytic activity toward the degradation of methylene blue (MB) solution. Moreover, recovered FST-0.6 composite with the help of an appropriate magnetic field maintained the activity without significant decline during multiple photocatalytic tests. Accordingly, a rational mechanism was proposed to explain why the FST-0.6 composite showed excellent photocatalytic performance.