A Green Sol–Gel Route to Fe ₃ O ₄ @TiO ₂ –CuO Photocatalysts with Structural Stability, Visible–Light Activity, and Magnetic Recoverability

In this work, we present the synthesis of a multifunctional Fe₃O₄@TiO₂-CuO photocatalyst, integrating <i>Magonia pubescens</i> plant extract and urea-assisted pH modulation. The as-prepared composite exhibits outstanding visible-light photocatalytic performance, achieving 75% degradation of rhodamine B (RhB, 15 ppm) after 5 h under 100 W LED irradiation and retaining more than 45% activity across four reuse cycles enabled by simple magnetic recovery. Notably, urea-assisted synthesis reduces iron leaching by ∼50%, preserving magnetic integrity and enabling efficient catalyst separation. Comprehensive structural, morphological, and surface analyses (TEM, XRD, XPS, XRF, VSM, ICP, GC-MS) confirm the formation of a robust, magnetically recoverable hybrid with a narrowed band gap of 1.65 eV and enhanced stability. GC-MS analysis revealed progressive mineralization of RhB into low-molecular-weight intermediates.