Schottky junctions integrated with S-scheme heterojunctions in recyclable loaded ZnIn2S4/UiO-66/calcined graphite felt photocatalysts with enhanced carrier separation for photocatalytic degradation

Photocatalytic technology holds significant potential in the purification of antibiotic wastewater. However, efficient carrier separation and convenient recyclability are crucial for the practical application of photocatalysts. Herein, a loaded ZnIn₂S₄/UiO-66/calcined graphite felt (ZU/C-GF) composite photocatalyst was demonstrated to achieve efficient and stable removal of tetracycline hydrochloride (TCH) from water. Detailed characterization and theoretical calculations suggested that ZnIn₂S₄ could form a Schottky junction with C-GF and an S-scheme heterojunction with UiO-66. The internal electric field (IEF) at the interface could promote the migration of photoelectrons, while the Schottky barrier could inhibit electron backflow. This synergistic strategy maximized the separation of photogenerated electrons and holes, thereby enhancing the photocatalytic performance. The optimal composite material exhibited the highest removal efficiency (97.0 %) and reaction rate (0.02312 min⁻¹) while maintaining comparable degradation performance under solar irradiation. Additionally, this C-GF-based immobilization scheme allowed for rapid recovery and reuse of the photocatalyst, effectively addressing the challenge of recycling. ZU-10/C-CF demonstrated stable reusability after five consecutive cycles, revealing its significant potential for practical applications. This work presents novel insights for coupling Schottky junctions and S-scheme heterojunctions, and describes a more convenient approach for the continuous and stable treatment of antibiotic wastewater.