Study on the preparation of nanostructured ZnO/BiOCl0.8I0.2 composite and its photocatalytic behavior on the degradation of tetracycline

A nanostructured ZnO/BiOCl0.8I0.2 (The theoretical molar ratio of Bi, O, Cl, and I elements in the raw materials of BiOCl0.8I0.2 is 1:1:0.8:0.2) composite photocatalyst was synthesized using the hydrothermal method using ZnO hollow nanospheres prepared using a template method as the base material. Compared with pure ZnO hollow nanospheres and BiOCl0.8I0.2 nanosheet samples, the composite photocatalyst effectively separates photoexcited carriers through the formation of heterojunctions, thereby significantly enhancing the degradation performance in tetracycline (TC) solution. The impact of the BiOCl0.8I0.2 to ZnO mass ratio on the photocatalytic performance of the composite was explored. The sample with a mass ratio of 20% shows the best photocatalytic performance, which is attributed to its high solar light absorption and the formation of heterojunctions with an S-scheme carrier transfer mechanism within the sample. Under this photocatalysis, the degradation efficiency of a 30 mg/L TC solution reached 89.8% within 30 min, which is 2.07 and 1.82 times higher than that of pure ZnO and BiOCl0.8I0.2 samples, respectively. In addition, the composite photocatalyst exhibits excellent structural and performance stability during photocatalysis, thus exhibiting practical application potential in water pollution treatment.