Boosting photocatalytic mineralization of polystyrene microplastics with a TiO₂@UiO-66 advanced semiconductor...

Photocatalysis is a promising technology for the removal of microplastics from aquatic environments. A current research focus lies in developing photocatalytic materials capable of efficiently degrading microplastics under visible or ultraviolet (UV) light irradiation. In this study, a TiO₂@UiO-66 heterostructured nanocomposite was synthesized and employed for the photocatalytic degradation of polystyrene (PS) microplastics under UV illumination at room temperature. The synthesized materials were characterized by XRD, SEM, UV-Vis/DRS, PL spectroscopy, XPS, and EDX mapping. The TiO₂@UiO-66 composite exhibited significantly higher photocatalytic activity toward PS microplastic degradation compared with pristine TiO₂ and UiO-66 under UV light irradiation. Approximately 63% of PS microplastics (150 ppm) were degraded after 30 h of irradiation at an intensity of 4 mW·cm^-2 under natural pH conditions. The analysis of total organic carbon indicated a decline in the removal efficiency of PS microplastics with increasing concentration. Liquid chromatography-mass spectrometry and Fourier transform infrared analyses revealed the formation of soluble organic intermediates such as aldehydes and carboxylic acids during the degradation process. These results demonstrate that the TiO₂@UiO-66 photocatalyst is a promising material for the removal of PS microplastics in aqueous environments, where the ^•OH, O₂^{• -} play a dominant role in the degradation mechanism.