MOF-on-MOF-derived hollow tubular ZnFe2O4/Er-ZnO heterojunctions for the efficient degradation of tetracycline by visible light photocatalysis

Semiconductor photocatalytic technology is recognized as one of the effective technologies for using solar energy to solve current environmental problems. In this study, a Z-scheme heterojunction ZnFe 2 O 4 /Er-ZnO hollow nanotube composite was prepared by hydrothermal method. The results show that the degradation efficiency of tetracycline (TC) in ZnFe 2 O 4 is only 51 %, while the degradation efficiency of ZnFe 2 O 4 /2% Er-ZnO hollow tube composites is as high as 97 %. At the same time, ZnFe 2 O 4 /2% Er-ZnO has a larger specific surface area (specific surface area of 224.39 m 2  · g −1 ), which is 27 times that of ZnFe 2 O 4 (specific surface area of 8.30 m 2 ·g −1 ). Density functional theory (DFT) calculations and experimental analysis show that the doping of Er, the unique hollow structure and the formation of heterojunction make ZnFe 2 O 4 /2% Er-ZnO have a large specific surface area, efficient carrier separation ability and strong redox ability, so the Z-scheme heterojunction ZnFe 2 O 4 /2% Er-ZnO hollow tubular composites have strong degradation ability for tetracycline. In addition, the liquid chromatography-mass spectrometry (LC-MS) analysis technique was used to propose the possible degradation pathways of antibiotics, which provided ideas for the treatment of water pollution.