Rational design of interwoven SiO2@Gr/N-CNT heterostructures from Fe–C–Si alloys for achieving superior electromagnetic wave absorption

Abstract

This study prepared SiO₂@graphite (Gr)/N-doped carbon nanotube (N-CNT) (SiO₂@Gr/N-CNT) composite materials with an Fe–C–Si alloy and melamine as raw materials using simple acid leaching, mechanical ball milling, and in situ pyrolysis. The composites feature a unique structural design in which three-dimensional N-CNTs are intertwined with SiO₂@Gr, forming a heterogeneous interface architecture. Owing to its structural advantages, the composite demonstrates outstanding electromagnetic-wave-absorption performance, achieving a minimum reflection loss of −66.05 dB at a matching thickness of 2.84 mm and an EAB of 4.84 GHz at a thickness of 1.77 mm. Additionally, a CST-based radar cross-section simulation analysis of the material further validates its practical application value. An analysis of the absorption mechanism of the composite indicates that its superior performance stems from the synergistic cooperation of multiple loss pathways, encompassing interfacial polarization, dipole polarization, and multiple scattering. This study offers new perspectives and a feasible technical route for constructing high-performance electromagnetic-wave absorbers.