MOFs derived Co@C@MnO nanorods with enhanced interfacial polarization for boosting the electromagnetic wave absorption.

In our work, CoMn-MOF-74 precursors are prepared with rough surface by etching method, and a large number of Co@C@MnO heterogeneous interfaces are engineered via a facile calcination process. By adjusting the etching time, the microstructures of the precursors can be tuned, resulting in a different number of heterogeneous interfaces between Co, carbon and MnO in the Co@C@MnO nanorods. Therefore, the Co@C@MnO nanorods achieve excellent EMW absorption performance, which can be attributed to the enhancement of dielectric loss induced by the enhanced interfacial polarization loss. Besides, the conduction loss and the multiple reflection induced by the porous carbon can enhance the dissipation of electromagnetic wave. The existence of Co nanoparticles is also conducive to the dissipation of electromagnetic wave by enhancing magnetic loss. The MnO@C nanorods with porous structures exhibit significantly enhanced electromagnetic wave absorption properties with the filler loading of 20 wt%, and a maximum reflection loss (RL) of -64.4 dB, and the bandwidth of RL less than -10 dB (90% absorption) is 6.7 GHz. Our work is expected to improve the specific surface area of MOFs precursors by etching method, thus making their derivatives have complex compositions and novel structures to achieve excellent electromagnetic wave absorption properties.