MOF-Derived Porous Co/C Nanocomposites with Excellent Electromagnetic Wave Absorption Properties

Composites incorporating ferromagnetic metal nanopartices into a highly porous carbon matrix are promising as electromagnetic wave absorption materials. Such special composite nanomaterials are potentially prepared by the thermal decomposition of metal–organic framework (MOF) materials under controlled atmospheres. In this study, using Co-based MOFs (Co-MOF, ZIF-67) as an example, the feasibility of this synthetic strategy was demonstrated by the successful fabrication of porous Co/C composite nanomaterials. The atmosphere and temperature for the thermal decomposition of MOF precursors were crucial factors for the formation of the ferromagnetic metal nanopartices and carbon matrix in the porous Co/C composites. Among the three Co/C composites obtained at different temperatures, Co/C-500 obtained at 500 °C exhibited the best performance for electromagnetic wave absorption. In particular, the maximum reflection loss (RL) of Co/C-500 reached −35.3 dB, and the effective absorption bandwidth (RL ≤ −10 dB) was 5.80 GHz (8.40 GHz–14.20 GHz) corresponding to an absorber thickness of 2.5 mm. Such excellent electromagnetic wave absorption properties are ascribed to the synergetic effects between the highly porous structure and multiple components, which significantly improved impedance matching.