3D Porous Graphene with Atomic Fe Coordinated by Pyrrole-N Dopants for Efficient Electromagnetic Wave Absorption with Low Filler Loading and Thin Thickness.

Achieving effective electromagnetic wave (EMW) absorption performance with less than 2 mm remains a significant challenge in developing EMW absorption materials. Herein, Fe atoms embedded into NH-treated 3D porous graphene (3DPG-NH-Fe) are synthesized via a simple method of Fe ion impregnation for efficient EMW absorption. The NH-treated process enables the formation of specific pyrrole-N dopants in 3DPG, which provide the anchoring sites for complexing Fe atoms to construct FeN moieties. Compared to pristine 3DPG, 3DPG-NH-Fe exhibits remarkable EMW absorption characteristics, achieving a minimum reflection loss (RL) of -56.35 dB and an effective absorption bandwidth (EAB) of 4.45 GHz at a low filler loading of 3 wt.% and a thin thickness of 1.4 mm, exceeding the most of reported graphene-based EMW absorption materials. The outstanding performance is critically attributed to the incorporation of the specific Fe coordinated by pyrrole-N dopants with a strong orbital hybridization of N-p and Fe-3d into graphene, which not only produces additional dipoles but also generates high spin Fe atomic magnetic moment, thus enhancing both dielectric loss and magnetic loss for EMW. This work demonstrates a new route for modulating the electromagnetic characteristics of graphene to achieve low filler loading and thin thickness of EMW absorption.