MOF-derived La/ZnO–TiO2 composite with enhanced photocatalytic ability for degradation of tetracycline

Abstract

Developing effective and stable photocatalysts for organic pollutants degradation are still a big challenge in practical water treatment now. In this work, La doped ZnO–TiO2 composite (La/ZnO–TiO2) were successfully fabricated by using PVP modified ZIF-8/TiO2 as template via the absorption and pyrolysis routes. All as-fabricated materials were analyzed by XRD, SEM, TEM, BET, XPS, UV–vis absorption spectra and ESR spectra. PVP modified ZIF-8/TiO2 was fully transferred into ZnO–TiO2 after being pyrolyzed at high temperature under air atmosphere. The doping of La can make ZnO–TiO2 exhibiting red-shifted, which is attributed to the capture of photo-generated electrons by La, leading to the effective separation between photo-generated electrons and holes. Furthermore, the photocatalytic performance of all as-fabricated materials were explored by degradation of tetracycline (TC) solution under UV light irradiation. La/ZnO–TiO2 exhibits excellent stability. And the photocatalytic degradation rate of La/ZnO–TiO2 is 99.2%, which is even higher than ZnO (87.4%), ZnO–TiO2 (87.4%), P25 (TiO2) (92.7%). More than that, the effect of catalyst's dose, effect of TC concentration and effect of pH for TC degradation have been well explored. The excellent photocatalytic performance of La/ZnO–TiO2 makes it possible to be applied for degradation of organic pollutants in practice.