1D-3D mixed-dimensional MnO2@nanoporous carbon composites derived from Mn-metal organic framework with full-band ultra-strong microwave absorption response

Nano-porous carbon (NPC) composites derived from metal-organic frameworks (MOFs) possess effective microwave absorption (MA) properties. However, the fabrication of MOF-derived NPC composites with full-band MA performance is challenging. In this work, the effect of the bandgap on the microwave dielectric behavior of Mn-MOF derivatives was investigated. The results demonstrated that a narrower MnO2 bandgap resulted in higher conductivity and a larger dielectric constant of the corresponding materials. The three-dimensional (3D) MnO@NPC composites achieved excellent low-frequency MA ability. The maximum reflection loss (RL) of MnO@NPC carbonized at 800 degrees C reached 54.38 dB at 5.12 GHz. The 1D-3D mixed-dimensional MnO2@NPC composites with the ultra-strong MA response in the full band were obtained by oxidizing MnO@NPC to MnO2@NPC. MnO2@NPC-800 showed superior MA capacity with the maximum RL value equal to -63.21 dB at 12.48 GHz and 2.05 mm thickness. The maximum RL values in S, C, X, Ku bands also exceeded -50 dB. Such an outstanding MA performance of MnO2@NPC-800 composite was attributed to the MnO2 presence and its multidimensional structure. This work provides the foundation for the fabrication of MOF-derived materials capable of full-band MA.