Microwave-assisted Solvothermal Synthesis of Bimetallic Metal-Organic Framework for Efficient Photodegradation of Organic Dyes

Iron metal-framework MIL-88B(Fe) (chemical formula: Fe3O [C6H4(CO2)2]3OH.nH2O) has received much attention as a promising catalyst for the degradation of organic dyes. Unfortunately, some MOFs suffer from a deficiency of stability; thus, limiting their range of applications. To handle this problem, we attempted to replace Fe3+ ions with other metal ions at different ratios to improve the photocatalytic performance. Briefly, M/ Fe-MOFs (M = Ni, Mg and Sn) with remarkably different properties were obtained using the microwave-assisted solvothermal method. The morphology of the synthesized bimetallic metal-organic frameworks was characterized by SEM and TEM; while their physical and chemical properties were defined by XRD, FT-IR, Raman, XPS, UV-vis DRS, and BET. The photocatalytic performance of the prepared materials was explored through the photocatalytic degradation of organic dyes (rhodamine B (RhB), crystal violet (CV), methyl orange (MO) and methylene blue (MB)) under irradiation of visible light was explored. The result showed that 10%Ni/Fe-MOF sample achieved above 96 % of RhB removal after 120 min of irradiation. The effects of pH solution, catalyst dosage and RhB concentration on RhB decomposition efficiency were carefully investigated. Furthermore, the present study has proposed a mechanism of RhB dye degradation reaction by bimetallic MOFs catalysts. Additionally, the free radical scavenging experiment has found that OH center dot and h+ radicals took the main responsibility for RhB decomposition. The stability and reliability of 10%Ni/Fe-MOF were also evaluated via the leaching and reusability tests. Interestingly, the photocatalyst performance experienced a negligible reduction after five consecutive usages. The results are expected to broaden the knowledge of bimetallic MOF synthesis and its applications.