Preparation of core-shell heterojunction photocatalysts by coating CdS nanoparticles onto Bi4Ti3O12 hierarchical microspheres and their photocatalytic removal of organic pollutants and Cr(VI) ions

Herein we have assembled CdS nanoparticles onto the surface of Bi4Ti3O1 (BTO) hierarchical microspheres to construct core-shell BTO/CdS heterojunction photocatalysts. The as-prepared samples are systematically analyzed by various methods (e.g., XRD, SEM, TEM, XPS, UV–vis DR spectroscopy and FTIR spectroscopy), confirming the formation of core-shell structured BTO/CdS composites. Photocurrent response and EIS analyses demonstrate that enhanced separation of photogenerated electron-hole pairs is realized in the BTO/CdS heterojunctions. Simulated-sunlight driving photodegradation of methylene blue (MB) reveals that the optimal composite sample 20%BTO/CdS is endowed with a photocatalytic activity about 1.6 and 3.3 times higher than that of bare CdS and BTO, respectively. Moreover, the 20%BTO/CdS heterojunction photocatalyst also exhibits excellent photocatalytic elimination of methyl orange (MO)/rhodamine B (RhB)/MB mixture dyes, ciprofloxacin (CIP), sulfamethoxazole (SMX), tetrabromobisphenol A (TBBPA) and Cr(VI) ions. The enhanced photocatalytic mechanism of the BTO/CdS heterojunction photocatalysts was discussed based on a Z-scheme carrier transfer process.