Ternary Fe3O4/MoS2/BiVO4 nanocomposites: novel magnetically separable visible light-driven photocatalyst for efficiently degradation of antibiotic wastewater through p–n heterojunction

The noble metal-free ternary Fe3O4/MoS2/BiVO4 p–n heterojunctions photocatalyst were prepared via a simply hydrothermal method, which possessed the unique nanospheres-on-microspheres heterostructure. The Fe3O4/MoS2/BiVO4 composite photocatalyst exhibited higher photocatalytic degradation of tetracycline hydrochloride (TCH) than those of MoS2, BiVO4 under visible light irradiation (λ > 420 nm). Especially, when the Bi/Mo molar ratio reached 30:1 (FMB3), the FMB3 displayed the highest photocatalytic activity, which can degrade 83% TCH (20 mg/L) within 90 min. The enhanced photocatalytic activity of the ternary photocatalyst could be attributed to the energy band matching and reduction of the charge transfer resistance to promote the spatial separation and reduce the recombination of photogenerated charge carriers due to the formation of built-in electric field by p–n heterojunctions between MoS2 and BiVO4. Additionally, MoS2 can be used as cocatalyst to enhance the separation efficiency of BiVO4 catalyst carrier and thereby improving the photocatalytic activity. Furthermore, the photocatalyst displayed highly stable recycling performances, which can be separated rapidly with an external magnetic field and be reused for five cycles and remain 91.8% of the first time.