Bimetallic MgFe2O4@BiBTC hybrids for efficient photocatalytic degradation of rhodamine B

Abstract

This study involved the incorporation of magnesium ferrite (MgFe₂O₄) nanoparticles into a bismuth-based metal–organic framework (BiBTC) to develop a novel magnetic photocatalyst, MgFe₂O₄@BiBTC, via a solvothermal approach. The MgFe₂O₄@BiBTC structural, optical, magnetic, and surface characteristics were thoroughly examined using XRD, FT-IR, SEM-EDS, TEM, XPS, UV-vis DRS, and VSM techniques. The findings indicated that MgFe₂O₄ in conjunction with BiBTC at a mass ratio of 20% (MFB20) exhibited the highest efficiency in Rhodamine B (RhB) decomposition, achieving 97.98%, under the parameters of catalyst mass 10 mg, RhB concentration 20 mg L⁻¹, volume 50 mL, adsorption duration 60 min, and LED illumination time 120 min. The degradation rate of RhB of MFB20 (k = 0.03458 min⁻¹) was about 1.5-fold higher than that of pristine BiBTC (k = 0.02334 min⁻¹). The enhanced activity is attributed to a type-II heterojunction between MgFe₂O₄ and BiBTC that drives electron transfer and photogenerated hole formation at the interface of the two phases, therefore enhancing charge separation and minimizing recombination, which improves the degradation efficiency of RhB. Radical scavenging tests found superoxide radicals (˙O₂⁻) as the most reactive species. Although MFB20 shows a reduced saturation magnetization relative to MgFe₂O₄, the coercivity remains essentially unchanged, indicating that the ferrite phase maintains its magnetic integrity within the composite.