Encapsulation of high specific surface area red blood cell-like mesoporous carbon spheres by magnetic nanoparticles: A new strategy to realize multiple electromagnetic wave loss mechanism

Abstract

Accompanied by the increasingly serious disordered electromagnetic radiation to trigger electromagnetic pollution become a new generation source which is harmful and difficult to protect, it is still a enormous challenge to develop a novel microwave absorbing materials (MAM) with low-density and wide absorption band. Here, we propose an advanced strategy to encapsulate red blood cell-like mesoporous carbon spheres with magnetic nanoparticles in terms of the problems of poor impedance matching, narrow absorption band of single dielectric loss material or high density of single magnetic loss material. A novel microwave absorber (MRBC), exhibited with the characteristics of ultra-high specific surface area (BET specific surface area: >500 m2/g), uniform mesoporous properties (Pore diameter: 7–8 nm) and special hollow structure and composed of carbon spheres with intact red blood cell morphology and magnetic nanoparticles, was obtained by the combination of double vacuum sintering processes and glycolate pyrolysis process. The unique microstructure and the synergistic effect of multiple dielectric loss and magnetic loss capability make MRBC-3 achieve an effective bandwidth of 5.77 GHz at a low filling rate (15 wt%) and an ultra-thin thickness (1.74 mm). Meanwhile, the minimum reflection loss of MRBC-4 is −64.26 dB. Furthermore, we use normalized input impedance to discuss the special properties of quarter wavelength matching layer, and verify the location of minimum reflection loss.