Novel hybrid Sr-doped TiO2/magnetic Ni0.6Zn0.4Fe2O4 for enhanced separation and photodegradation of organics under visible light

Titanium dioxide (TiO2) has been intensively used as a photocatalyst for the degradation of organic pollutants in water, but is typically obstacle by a low efficiency, costly separation, limited visible light response, and poor recyclability. Herein, we provided a reliable method to simultaneously tackle these four obstacles by developing an integrated and multifunctional hybrid photocatalyst/magnetic material, i.e., Sr–TiO2/Ni0.6Zn0.4Fe2O4. This novel hybrid not only demonstrated a high efficiency (90–100%) and a good cycling performance (90% maintenance) for photodegradation of bisphenol A (BPA) under both UV and visible light irradiation, but it can also efficiently work at a wide pH range (4–10) and can be easily separated from water for reuse only by introducing an external magnetic field. The materials structure-to-activity correlation has also been investigated. It was found that doping Sr2+ and a coupling magnetic material with TiO2 could extend the visible light response and create active defects in TiO2, which were responsible for the nearly three times higher activity than that of commercial TiO2(P25) under visible light. On the other hand, doping excessive Sr2+ lowered the surface area, enlarged the crystalline size and caused particle aggregation; thus, leading to a decrease in photocatalytic activity of the hybrid. These further modifications in the hybrid materials can provide a competitive alternative to control the organic pollutants in waste water.