Photocatalytic degradation of oxytetracycline by UiO-66 doped three-dimensional flower-like MoS2 heterojunction: DFT, degradation pathways, mechanism

Background: MoS2 has potential in the photocatalytic degradation. The combination of UiO-66 (University of Oslo) and MoS2 not only accelerates the electron transfer efficiency but also increases active sites, thereby further improves the photocatalytic activity.Methods: The three-dimensional flower-like MoS2/UiO-66 heterojunctions were prepared by in-situ hydrothermal method, which took advantage of metal-organic framework and semiconductor material. Oxytetracycline degradation was used to assess the photocatalytic performance, and the effects of catalyst dosage and solution pH on the performance were looked into. Significant findings: MoS2 nanosheets formed three-dimensional flower-like spheres on the surface of UiO-66 particles as they expanded in all directions. The unique structure exposed more active sites and provided sufficient surface reaction sites for the reactants. The composite had a broad-spectrum light response, and the oxytetracycline degradation efficiency reached 86.6 % after 120 min' irradiation. The band structure and density of states of MoS2 were calculated. The possible degradation paths were deduced by theoretical calculation and experimental detection. This excellent photodegradation can be attributed to the fact that Z-type heterojunction promoted the separation of photogenerated electron-hole pairs, prolonged the carrier lifetime, and generated more active substances. In addition, the cyclic test showed that the composite material had good repeatability and potential application prospect.