Porous carbon composite nanosheets loaded with magnetic FeNi/NiFe2O4 and dielectric SiO2 nanoparticles for adjustable microwave absorption

Abstract

According to the escalating concern regarding the health hazards associated with electromagnetic radiation, the significance of absorbing materials underscores which could mitigate the healthy risks. While magnetic materials offer excellent absorption performance, their high density poses challenges to achieving optimal absorption efficiency. Conversely, carbon-based materials are known for their lightweight and versatile but face impedance matching issues. To address these obstacles, carbon/magnetic composite materials have been explored. However, their absorption performance has not fully met requirements due to weaker magnetic properties and increased density. Herein, we synthesized a porous carbon material embedded with magnetic FeNi/NiFe2O4 and dielectric SiO2 nanoparticles (FeNi-NiFe2O4-SiO2@PC) using carbonthermal method. By adjusting the ratio of polyvinylpyrrolidone to nitrates, the electromagnetic wave (EMW) absorption performance is adjusted. The FeNi-NiFe2O4-SiO2@PC composites display remarkable EMW absorption properties, achieving a minimum reflection loss of −69.9 dB at a thin thickness of 1.495 mm and a maximum effective absorption bandwidth of 5.68 GHz, covering the range from 12.32 to 18.0 GHz at a thickness of 1.92 mm. This outstanding performance can be attributed to the favorable impedance matching and the three-dimensional porous structure, which facilitates a 3D transmission network for multiple reflections. Additionally, the presence of FeNi, NiFe2O4, and SiO2 nanoparticles enhances magnetic loss, conductive loss, interface polarization, and dipolar polarization, leading to excellent ab. Hence, this work offers insights into the composition design of high-performance absorbing materials.