From 3D to Thin 2D MIL-100(Fe) Photocatalyst Coupled with g-C 3 N 4 /Fe 3 O 4 : A Dimensional Innovation for Enhanced RhB Photodegradation

Two-dimensional metal–organic framework (2D-MOF) photocatalysts have gained significant attention for environmental remediation due to their improved mass transfer and photocatalytic activities. In this study, a photocatalyst based on the quasi-two-dimensional MIL-100(Fe), graphitic carbon nitride (g-C 3 N 4 ), and magnetite was synthesized. All materials were thoroughly characterized via SEM, TEM, XPS, VSM, and TGA analyses. Compared to 3D-MIL-100(Fe), the quasi- two-dimensional MIL-100(Fe)-based photocatalyst exhibited significantly enhanced performance in the photodegradation of Rhodamine B under visible light. Thanks to the photocatalyst’s 2D morphology and more accessible active sites, adsorption equilibrium was achieved in 60 min, compared to over 200 min for the 3D-MIL-100(Fe). Photodegradation of 99% was reached within 23 min, compared to less than 60% for the 3D-MIL-100(Fe) under the same conditions. The photodegradation mechanism proceeded via the formation of radical species, where the main active species were in the order of holes > hydroxyl radicals > superoxide radicals. Key parameters in photodegradation experiments were optimized via Box–Behnken design. The chemical and structural stability of the prepared photocatalyst was studied for up to 6 cycles, and the data showed a high performance of over 98% photodegradation. The proposed method was reproducible and yielded high amounts, showing great potential for sustainable environmental applications.