Carbon spheres@MnO core-shell nanocomposites with enhanced dielectric properties for electromagnetic shielding.

Carbon spheres (CS)@MnO core-shell nanocomposites, with MnO nanoflakes uniformly coating at the surface of CS cores, were successfully synthesized by a facile water-bathing method. MnO amounts is estimated to be 24.7 wt% in CS@MnO nanocomposites. A high dielectric loss value and an electromagnetic shielding effectiveness of 16‒23 dB were observed for the CS@MnO in the frequency range of 8‒18 GHz, which is mainly attributed to the enhanced absorption loss. The incorporation of the CS with MnO improves the electrical conductivity. Meanwhile, the electromagnetic impendence matching has been significantly ameliorated. Moreover, the increasing interfaces between the CS and MnO facilitate the microwave attenuation as well. Thus, the electromagnetic shielding performances were greatly enhanced. Our findings provide an effective methodology for the synthesis of the CS@MnO core-shell nanocomposite for potential electromagnetic applications.