Microwave absorption performance of 2D Iron-Quinoid MOF

The excellent properties including high porosity, large specific surface area, low density, and strong controllability of metal-organic frameworks (MOFs) make them one of the preferred materials for a plethora of applications. One particular intriguing application, among others, is microwave absorption, to which majority of research has been devoted by using MOF as templates to prepare porous carbon via carbonization. Contrary to such approach, in this study we propose a novel strategy based on leveraging the intrinsic attributes of MOF. Through a simple and rapid microwave solvothermal method, lamellar redox-active iron-quinoid MOFs were synthesized and their morphology and crystallinity are modulated as a function of reaction temperature. The conductivity of the prepared MOF reached up to 2 x 10(-3) S/m, which is comparable to that of semiconductors. In addition, magnetic hysteresis was observed at 300 K. The reaction temperature proved pivotal to attain maximum microwave absorption of -73.5 dB at 13.8 GHz with a matching thickness of 3.3 mm. Effective absorbing bandwidth with a reflection loss below -10 dB can be also gained in a wide frequency range of 9.8-15.9 GHz. The optimal microwave absorbing performance was mainly attributed to the simultaneous implementation of magnetic and electrical loss in a single iron-quinoid MOF resulting in adequate impedance matching through modulable magnetic and electric properties. The developed iron-quinoid MOF material opens up new opportunities to achieve high-efficiency, lightweight and tunable microwave absorbers. The material-structure coupling strategy here is instrumental to developing next-generation high-performance microwave absorbing materials.

Automated summary

In this study, a new strategy was proposed to synthesize lamellar redox-active iron-quinoid MOFs with excellent conductivity and magnetic properties for optimal microwave absorption performance. By modulating the morphology and crystallinity of MOF, adequate impedance matching was achieved through the simultaneous implementation of magnetic and electrical loss, opening up new opportunities to develop high-efficiency, lightweight, and tunable microwave absorbers.