Highly Efficient Fe 3 O 4 /TiO 2 Nanocomposites for UV‐assisted Degradation of Methylene Blue via KHSO 5 Activation

Abstract Fe 3 O 4 /TiO 2 nanocomposites were synthesized with varying Fe 3 O 4 loadings (0.5–2 wt%) to enhance photocatalytic degradation of methylene blue (MB) under UV light. Fe 3 O 4 was prepared via a polyvinylpyrrolidone‐assisted hydrothermal method and integrated with TiO 2 to form composites TF1‐TF4. The photocatalytic performance was evaluated in the presence of oxidants. Among them, TF4 (2 wt% Fe 3 O 4 ) activated with KHSO 5 exhibited superior performance, achieving 99% MB removal within 120 min and the highest degradation rate constant (28.27 ± 0.56 x 10 −3 min −1 ). The enhanced activity is attributed to the synergistic effect between Fe 3 O 4 and TiO 2 , promoting charge separation and facilitating SO 4 .− radical generation from KHSO 5 . TF4 also exhibited a reduced bandgap (1.9 eV), an improved surface area, and excellent structural integrity. Reusability studies confirmed its high stability over 5 cycles with negligible performance loss. This work demonstrates the effectiveness of KHSO 5 ‐activated Fe 3 O 4 /TiO 2 , particularly TF4, as a robust, recyclable photocatalyst for dye degradation and wastewater treatment.