Magnetic composite photocatalyst ZnFe2O4/BiVO4: synthesis, characterization, and visible-light photocatalytic activity.

Magnetic composite ZnFe2O4/BiVO4 was successfully synthesized by the one-step chemical coprecipitation method. The photocatalytic activity of BiVO4 was improved by doping ZnFe2O4 that possessed a narrow band gap, which enabled the ZnFe2O4/BiVO4 composite to show increased visible-light absorption and further generate more photo-produced electrons than pure BiVO4. The experimental results showed that the photocatalytic ability of the composite was better than that of pure BiVO4 under visible light irradiation. The n-type ZnFe2O4 nanoparticles were uniformly distributed on the surface of n-type BiVO4, leading to the formation of n-n-type heterogeneous structures in the composite system. Since CB and VB potentials of ZnFe2O4 and BiVO4 were differential, the photo-produced electrons and holes would migrate to a position at a relatively positive potential and a relatively negative potential, respectively, which enhanced the separation efficiency between photo-produced electrons and holes and thus further contributed to the enhancement of photocatalytic activity.