Facile synthesis of fumarate-type iron-cobalt bimetallic MOFs and its application in photo-Fenton degradation of organic dyes

Abstract

Water contamination from organic contaminants like dyes has wreaked havoc on the ecosystem and jeopardized people's health. To this end, in this experiment, the low-crystalline bimetallic MIL-88ACo/Fe-x (Co/Fe-x represents the Co/Fe molar ratio) was synthesized under mild conditions with fumaric acid as ligand, the best performing MIL-88ACo/Fe-2 can completely degrade the MB solution within 20 ​min (100 ​mL, 20 ​mg/L). At lower synthesis temperature, the morphology and coordination structure of MIL-88A(Fe) were greatly changed by the incorporation of Co2+, so that the bimetallic MIL-88ACo/Fe-2 had abundant unsaturated metal sites and oxygen defects. The photoelectrical tests found that the change of structure made the bimetallic MIL-88ACo/Fe-2 have a narrow band gap, photoresponsivity and electron-hole separation efficiency were all improved. Under simulated sunlight, MIL-88ACo/Fe-2 has good universal degradability to a variety of dyes (methyl violet, methyl orange, methylene blue, rhodamine B). In addition, the main active specie of MIL-88ACo/Fe-2 degrading organic dyes was investigated in this experiment, and the possible degradation mechanism was proposed, which provided a feasible idea for the development of efficient photo-Fenton catalysts.