ZIF-8-Derived ZnO and SnO2 Form ZnO@SnO2 Composites for Enhanced Photocatalysis under Visible Light

ZIF-8 was used as a precursor and was converted to ZnO by calcining at high temperature to remove the organic functional groups therein. Then ZnO@SnO2 composites were synthesized by hydrothermal method using ZnO as the carrier. All samples were characterized by XRD, SEM, EIS, Transient photocurrent test and Mott-schottky test. The photodegradation effects of pristine ZnO, SnO2 and ZnO@SnO2 composites on tetracycline (TC) were evaluated and the best results were obtained (ZnO@SnO2=2 : 1), which could remove 91.2 % of TC under visible light irradiation. The effects of pH, ionic strength, and TC concentration were researched in batch experiments. ZnO@SnO2=2 : 1 showed favorable photocatalytic activity and stability, including pH and resistance to ionic strength. The enhanced photocatalytic activity of the ZnO@SnO2=2 : 1 composite could be ascribed to the lower recombination probability of electron-hole pairs in the heterojunction and the enlarged surface area for TC adsorption during photodegradation. This study provided a reference for heterojunctions with excellent photocatalytic properties.