Harvesting yolk-shell nanocomposites from Fe-MIL-101 self-template in NaCl/KCl molten salt environment for high-performance microwave absorber

Abstract

• The molten salt environment facilitates the construction of yolk-shell structure. • The resulting nanocomposite presents remarkable microwave absorption performance. • The effective absorption bandwidth covers the whole X band. • The synthesis strategy integrates the dielectric-magnetic dual-loss effect. The widespread exposure to electromagnetic radiation makes the development of electromagnetic absorber materials an important research topic. While most of the research effort is devoted to the optimization of material compositions, the construction of microstructures is equally indispensable for the enhancement of microwave absorption performance. In this work, we demonstrate how the microwave absorption performance of Fe@C composites can be improved by adopting Fe-MIL-101 as a precursor and being subsequently converted in a unique yolk-shell microstructure by the one-step carbonization process with the help of the NaCl/KCl molten salt environment. Contributed by both the compositions and the construction, the minimum intensity of reflection loss can be achieved at −45.53 dB at 9.85 GHz at a thickness of 2.5 mm, signifying an absorption ability of more than 99.99% incident microwave. Besides, the effective absorption bandwidth covers the whole X band at this thickness, ranging from 8.2 to 12.5 GHz, demonstrating that the microwave absorber could be applied in protecting objects from military radar detection. By integrating the advancement between the microstructure and the components, we propose a promising strategy catering to improving the microwave absorption performance.