In situ growth of hollow Cu2O nanosoheres on BiOBr nanosheets and its synergistic photocatalysis-persulfate activation activity

In this work, uniform hollow Cu₂O nanospheres are in situ grown on BiOBr nanosheets (Cu₂O@BiOBr, CB). The synergistic photocatalysis‑sodium persulfate (PS) activation was utilized to degrade tetracycline (TC) and rhodamine B (RhB). The RhB degradation efficiency of Vis/Cu₂O@BiOBr/PS system was 3.16 and 7.97 times higher than that of Vis/BiOBr/PS system and Vis/BiOBr system, respectively. Theoretical calculations showed that the Cu₂O@BiOBr heterojunction could effectively promote the charge separation of photogenerated electron-hole pairs. For TC, the degradation efficiency reached 90 % at 180 min by Vis/Cu₂O@BiOBr/PS. Furthermore, the toxicity of the degradation products for TC were evaluated by quantitative structure-effect relationship (QSAR), showing that compared to TC, some products have a higher acute toxicity and a higher bioaccumulation factor. As a result, the degraded solution had a higher toxicity to bacteria. This work warns us that the analysis of degradation products is crucial, otherwise, secondary pollution will pose a greater danger to the ecosystem. It is an urgent and crucial need to develop truly safe technology and it is highly desirable to get a complete mineralization technology for environmental sustainability.