Visible-light-driven photocatalytic activity of WO3/ZIF-67 S-scheme heterojunction for upgrading degradation of oxytetracycline

The S-scheme heterojunction engineering has been regarded as a promising strategy for sufficiently using photogenerated charge carriers. Therefore, how to design a suitable nanostructure for efficient photogenerated carrier transfer/separation can be the key to upgrading the photocatalytic activity. The present study was planned for the design and fabrication new type of S-scheme WO3/ZIF-67 heterojunction for the degradation of oxytetracycline (OTC) under visible light irradiation. First, the WO3 nanostructure was fabricated with the hydrothermal method. Subsequently, microcrystals ZIF-67 were grown onto WO3 nanoplate with the sol-gel method for designing a new type of WO3/ZIF-67 nanocomposite. HA–XRD pattern revealed epitaxial growth of ZIF-67 on the monoclinic α-WO3 surface. According to FESEM and TEM images, WO3 had a plate-like nanostructure with a thickness of about 90 nm that was spread heterogeneously on the surface and core of ZIF-67. The results revealed that 91.5% of OTC is degraded in 60 min of 20 W LED light following pseudo-first-order kinetics. Investigating the reaction mechanism and quenching tests indicated hydroxyl and superoxide anion radicals play a vital role in OTC degradation. The reusable ability of the prepared WO3/ZIF-67 nanocomposite was tested up to six runs with 82% removal efficiency, confirming the suitable recyclability and stability of the proposed photocatalyst. The smart strategy of designing metal organic framework-based photocatalysts provides an innovative perspective for the development of S-scheme heterojunctions for organic contamination degradation.