Synthesis, crystal structure of a iron-manganese bimetal MOF and its graphene composites with enhanced microwave absorption properties

FeMn-MOF (namely 35pFeMn) and FeMn-MOF/G composites (G: graphene; namely 35pFeMn/G-5 and 35pFeMn/G-10) were synthesized by facile one-pot solvothermal reactions. The structures and morphologies of the as-prepared samples were characterized by scanning electronic microscope (SEM), X-ray diffractometry (XRD),X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The structure of 35pFeMn was determined via the single crystal diffraction data and the XRD data indicate that the other composites have the identical structure to 35pFeMn. The experimental results show that graphene adhere entirely to the surface of the FeMn-MOF consisting of lamellar layer, moreover, the unique structure effectively decreases the density of the composites. Microwave absorption (MWA) properties of paraffin containing 40 wt% samples were investigated at room temperature in the frequency region of 1–18 GHz. The results indicated 35pFeMn/G-10 shows the most excellent MWA properties as its reflection loss is below −10 dB (90% absorption) at 12.59–16.17 GHz, and the minimal RL is almost −34.47 dB at 14.1 GHz with a sample thickness of only 1.5 mm. The intrinsic physical and chemical properties of the materials, the synergy of 35pFeMn and graphene, and particularly the interfacial polarization between 35pFeMn and graphene are fundamental to the enhancement of MWA properties. The as-prepared 35pFeMn/G-10 exhibits a promising designable approach to lightweight, strong-absorbed MWA materials.