Metal/N-Doped Carbon Nanoparticles Derived from Metal–Organic Frameworks for Electromagnetic Wave Absorption

Metal–organic frameworks (MOFs) have diverse structures and compositions, inspiring the boundless enthusiasm and creativity of researchers in the field of electromagnetism. The synthesis of MOF-derived nanomaterials for electromagnetic wave (EMW) absorption with ultrathin matching thickness (below 1.6 mm) is highly desired and challenging. Here, we demonstrate a general synthesis strategy for metal (Co, Ni, Fe)-based MOFs, which transformed into metal/metal-oxide nanoparticles (NPs) of being coated by nitrogen (N)-doped graphitized carbon. The obtained carbon-coated NPs show excellent EMW absorption properties. Specifically, Co-based MOFs are pyrolyzed into rhombic dodecahedrons with numerous ultrasmall Co NPs coated by N-doped carbon (Co-NC core–shell NPs). The synthesized Co-NC core–shell NPs possess a unique porous structure, abundant defects, and doped N heteroatoms, resulting in good magnetic loss (eddy current loss), dielectric loss (multiple reflections, interfacial polarization, conduction loss), and impedance matching. Therefore, the Co-NC core–shell NPs exhibit an excellent EMW absorption property with a very strong reflection loss of −56.5 dB at a matching thickness of only 1.58 mm. The effective absorption bandwidth (EAB) is 4.4 GHz. In addition, the EAB between 1 and 5 mm in thickness is up to 13.2 GHz, which already includes all C bands and X bands, even the absolute S bands and Ku bands. This work provides an avenue to design high-performance EMW absorption devices based on MOF-derived nanomaterials.