The Schottky junction between Ti3C2 MXene quantum dots and Bi2WO6 with oxygen vacancies accelerates charge separation and improves the photocatalytic degradation efficiency of tetracycline

Photocatalytic technology is widely used to solve environmental pollution problems, while most photocatalysts have a weak response to visible light, photogenerated charges are easy to recombine, and catalytic activity is limited. Herein, we used electrostatic self-assembly to tightly load Ti 3 C 2 MXene quantum dots (MQDs) onto Bi 2 WO 6 with oxygen vacancies (BWO) to obtain BWO@MQDs composite photocatalytic materials for the degradation of tetracycline (TC). The presence of oxygen vacancies in BWO provided more active sites, facilitating the reduction of O 2 to ·O 2 - by electrons. Moreover, MQDs and BWO could form a Schottky junction at the contact interface, and then the electrons on the BWO conduction band were transferred to MQDs, reducing the photogenerated electron-hole recombination. Under the optimal experimental conditions, the TC degradation efficiency of the BWO@MQDs photocatalyst was 88.12 %, which was 1.61 times that of original Bi 2 WO 6 , and the catalytic activity was well preserved after cycle stability testing. The possible photocatalytic mechanism and photodegradation pathway were revealed by UV–vis, XPS, ESR and LC-MS, the results indicated that ·O 2 - played the most dominant role in TC degradation and the final degradation products were mainly CO 2 and H 2 O. This study has important implications in oxygen vacancies and quantum dots co-modified bismuth-based materials for photocatalysis to solve water pollution problems.