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

Abstract

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/Ni_0.6Zn_0.4Fe₂O₄. 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.