Oxygen-defected WO3-OVs@Bi2MoO6 S-scheme micro flowers heterojunctions with promoted photocatalytic degradation of tetracycline

The synergy between surface oxygen vacancies (OVs) and heterojunction engineering holds promising potential for substantially enhancing photoelectric conversion efficiency through the optimization of photogenerated charge carrier transport. Herein, novel WO3-OVs@Bi2MoO6 S-scheme heterostructures are synthesized via a simple route for degradation of tetracycline hydrochloride (TC) using visible light. The S-scheme charge transfer mode markedly enhances the spatial separation and preservation of high-energy electrons/holes on Bi2MoO6 (reduction) and WO3-OVs (oxidation), consequently providing WO3-OVs@Bi2MoO6 photocatalysts with an improved redox capability. The optimal WO3-OVs@Bi2MoO6 heterojunction demonstrates enhanced visible-light-driven photocatalytic degradation of tetracycline, exhibiting 4.86-fold and 4.17-fold higher efficiency compared to WO3-OVs and Bi2MoO6, respectively, with superior stability and reusability. Confirmation of the existence of the S-scheme charge transfer mechanism and oxygen vacancies (OVs) is achieved through a combination of density functional theory (DFT) calculations and in-situ X-ray photoelectron spectroscopy (XPS), substantiating the enhancement of charge separation and redox capability. Specifically, the presence of oxygen vacancies (OVs) on the surface of WO3 nanofibers results in a reduction of the band gap energy due to the defect levels, consequently promoting increased electron conduction. Furthermore, the abundance of oxygen vacancies (OVs) expands the photo response range and facilitates charge transfer at the interface. This research opens new avenues for the successful photocatalytic degradation of tetracycline (TC) by integrating hierarchical S-scheme heterojunction design and cutting-edge defect engineering in photocatalytic heterojunctions.