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The 7:3LaCoO3/Bi2WO6 composite synthesized in this experiment had a significant effect on the degradation of TC in the solution under visible light (85.5% at 150min). The experimental results proved that the composite material not only had a high removal rate of TC in the water, but also could be recycled and met the requirements of environmental protection. XRD, SEM, FT-IR, XPS and other analysis showed that in the 7:3LaCoO3/Bi2WO6 composite, the two monomers LaCoO3 and Bi2WO6 were well combined together. The two active groups h+ and •O2- played an important role in the photocatalytic degradation process of the composite material. The electrons of the composite material moved from the conduction band of Bi2WO6 to the valence band of LaCoO3, which further enhanced the photocatalytic activity of the composite material. This research provided a new type of photocatalytic material for treating TC in water, also provided a certain theoretical support for the composite of lanthanide-based photocatalytic materials and bismuth-based photocatalytic materials.

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.