Fe/Fe₃O₄@N-Doped Carbon Hexagonal Plates Decorated with Ag Nanoparticles for Microwave Absorption

Electromagnetic (EM) interference and radiation affecting human health and the operation of precision electronic devices have drawn considerable attention in recent years. Herein, a promising microwave-absorbing material, Ag nanoparticles (AgNPs)-decorated Fe/Fe3O4@N-doped carbon (NC) composite, was designed and fabricated with the Fe2O3@polydopamine@Ag hexagonal plates as the precursor. Crystalline structure, phase conversion, micromorphology, static magnetic properties, and EM characteristics of the samples were studied by various analytical techniques. The EM parameters of the obtained samples could be manipulated by increasing the pyrolysis temperature, exhibiting gradually enhanced dielectric and magnetic loss. Optimizing the coating thickness turns out to be a critical factor for regulating microwave absorption. The product obtained at 600 °C performs a maximum reflection loss (RL) value of −37.5 dB (10.64 GHz, 1.6 mm) and an effective absorption bandwidth (RL < −10 dB) up to 7.36 GHz (10.64–18 GHz) with a thickness of only 1.4 mm. In addition, the possible EM wave absorption mechanisms were further investigated in detail. In sum, it has been confirmed that the as-obtained AgNPs-decorated Fe/Fe3O4@NC composite with ultrabroad absorption bandwidths and strong absorption capacity would be an attractive candidate material for effective EM absorption materials in the future.