Synthesis and Enhanced Microwave Absorption Performance of Co/MnO@C Composite Derived from Rod–like CoMn MOF–74

Microwave absorption materials have gained significant attention for their potential in electromagnetic interference shielding and stealth applications. However, single-component carbon materials often exhibit poor impedance matching and limited magnetism, necessitating the development of multifunctional composites. In this study, a facile and cost-effective synthesis route was employed to fabricate Co/MnO@C composites derived from CoMn MOF-74 precursors. The goal was to achieve a synergistic enhancement in microwave absorption by optimizing structural morphology, tailoring component composition, and reinforcing multiple loss mechanisms. Rod-like Mn@C nanostructures were synthesized initially, followed by Co ion doping to generate CoMn@C nanorods. The high-temperature pyrolysis process facilitated the in-situ reduction of Mn and Co species, leading to the formation of metallic Co and MnO embedded within a carbon matrix. X-ray diffraction (XRD) confirmed the successful phase transformation, while scanning electron microscopy (SEM) revealed well-defined nanorod structures with uniform morphology. Microwave absorption studies demonstrated that the molar ratio of Co to Mn played a crucial role in determining electromagnetic parameters, including dielectric and magnetic losses. Among the tested compositions, Co/MnO@C with a Co:Mn ratio of 0.6 exhibited the highest reflection loss of -30.7 dB at 12.0 GHz, with an effective absorption bandwidth of 4.5 GHz. The enhanced absorption was attributed to optimized impedance matching, effective attenuation mechanisms, and synergistic interactions between dielectric and magnetic components. This work provides a promising strategy for designing high-performance microwave absorbers through MOF-derived nanocomposite engineering.