Fe@CNx Nanocapsules for Microwave Absorption at Gigahertz Frequency

Abstract

In order to solve growing electromagnetic wave pollution issues, development of high-performance microwave absorption materials composed of dielectric loss and magnetic loss characteristics has been attracting considerable attention. Herein, we demonstrate an effective approach for the transformation of Fe@C into Fe@CNx nanocapsules by in situ microwave-assisted heating effect. Ascribed to the high effective microwave absorption capacity, the microwave energy could be localized around the nanoscale environment of Fe@C nanocapsules, resulting in the in situ chemical decomposition of urea precursor and the transformation of the initial graphitic shells to CNx shells. Microstructure characterizations coupled with complex permittivity spectra further reveal that the intrinsic dielectric enhancement for the Fe@CNx nanocapsules originates from the atomic-scale C–N complexes that induce the space charge separation and form the electric dipoles. The present study indicates a novel approach for in situ synthesizin...