Fabrication of p–n MoS2/BiOBr heterojunction with few-layered structure for enhanced photocatalytic activity toward tetracycline degradation

The MoS 2 /BiOBr heterojunction photocatalyst was successfully prepared by simple solvothermal process and used to remove tetracycline (TC) from water. The morphology, crystal structure, composition, and properties of the prepared samples were investigated by means of X-ray diffraction, scanning electron microscopy (SEM), Brunner–Emmet–Teller, UV-visible spectrophotometer, and X-ray photoelectron spectroscopy. SEM analysis showed that lamellar MoS 2 interspersed in the gap of BiOBr microspheres and formed spheroidal heterojunction structure. Among all the MoS 2 /BiOBr with different mass ratios, 5 wt.% MoS 2 /BiOBr displayed the highest photocatalytic activity, which can degrade 80.2% TC (40 mg/L) in 90 min and the rate constant is 0.01802 min –1 . It is 2.55 and 1.82 times higher than pure MoS 2 and BiOBr, respectively. It indicated the introduction of MoS 2 can not only promote the absorption band become broader, but also form the p–n MoS 2 /BiOBr heterojunction derives from the energy band matching and the formation of the built-in electric field which could improve the separation efficiency of photogenerated carriers. The study on photocat- alytic mechanism by active species capturing and electron spin resonance experiments proved that h + and • O 2 – were the predominant species in photocatalytic system. This research provides a strong practical support to construct highly efficient BiOBr-based p–n heterojunction photocatalysts for photocatalytic applications of degradation on organic pollutants in aqueous environment.