Preparation of core-shell structured Fe3O4@Sn-MOF composite and photocatalytic performance

Highlights: • A hydrothermal synthesis was used to fabricate the Fe₃O₄@Sn-MOF composite. • The as-prepared Fe₃O₄@Sn-MOF had a core-shell structure. • The Fe₃O₄@Sn-MOF had strong photoresponse and effective charge separation. • Fe₃O₄ as the magnetic nucleus improved the recovery rate of the composite. -- Abstract: The magnetic metal-organic framework composite Fe₃O₄@Sn-MOF with core-shell structure was successfully prepared by hydrothermal synthesis. It was characterized by XRD, TEM, BET, DRS, FT-IR, XPS and VSM. The photocatalytic performance of the composite was evaluated by degradation of Acid Red 3R (AR3R) dye under simulated light source. Under the conditions that the additive amount of the catalyst was 6.7 g/L, the initial concentration of AR3R was 50 mg/L and the initial pH of AR3R was 3.0, Fe₃O₄@Sn-MOF revealed the optimized photocatalytic activity with 100% degradation efficiency of AR3R at 30 min. The excellent photocatalytic ability was mainly ascribed to the effective charge separation, strong photo-response and rich active sites. Besides, using Fe₃O₄ as the magnetic nucleus was conducive to improve the recovery rate of the catalyst. The EPR and free radical analysis indicate that • O₂⁻ and • OH played important roles in the photocatalytic reaction. Meanwhile, a possible degradation process and mechanism were proposed by the full band scanning of AR3R, 3D-EEM fluorescence analysis and electrochemical measurement.