In-situ formation of low-dimensional, magnetic core-shell nanocrystal for electromagnetic dissipation

Rational design of low-dimensional, core-shell nanocrystals with superior synergistic dimensional-interfacial effect is promising to address the growing electromagnetic (EM) pollution challenge. Particularly, the monodispersed and core/shell component-controllable nanocrystal is highly desirable but remains challenging. Herein, a monodispersed core-shell nanocrystal consisting of a magnetic iron-based core and graphitized carbon (g-C) shell is synthesized via the in-situ pyrolysis of bamboo-derived lignin modified Fe3O4 (Fe3O4-lignin). The component of core can be controllably manipulated by altering the amount of lignin and a variety of iron-based cores, such as Fe3O4/Fe3C, Fe3C/Fe, Fe3O4/Fe3C/Fe and so forth, can be obtained using this in-situ pyrolysis approach. The result revealed that the optimized sub-13-nm-sized Fe–C nanocrystal displayed an ultra-wide EM absorption range (8.4–18.0 GHz) and the minimum reflection loss (RLmin) value was even reached as low as −47.11 dB at 8.0 GHz. The correlation of component-structure-dielectric or magnetic loss was further well investigated to reveal the EM dissipation mechanism. This novel method for sub-13-nm-sized magnetic nanocrystals is of great significance for the synthesis and design of nanocrystals and the mechanism study shed new sights for future high-performance electromagnetic absorbers.