N,S-Codoped Hollow Carbon Nanofiber/Multicomponent Nanoparticle Composites for High-Efficiency Lightweight Microwave Absorbers

Lightweight materials are attracting increasing attention as practical electromagnetic wave absorbers in the frequency range of 2–18 GHz. In this paper, N,S-codoped hollow carbon nanofibers/multicomponent nanoparticles (N,S-CNFs/Fe 2 O 3 /Fe 3 C/NiC x ) were successfully fabricated via facile chemical oxidation and high-temperature carbonization. The introduction of hollow structures and multicomponent nanoparticles creates abundant heterogeneous interfaces. The introduction of heteroatoms (N and S) improved defect concentrations. The N,S-CNFs/Fe 2 O 3 /Fe 3 C/NiC x composites reveal a strong reflection loss (RL, −49.39 dB at only a thickness of 1.5 mm) and a wide effective absorption bandwidth [EAB, RL < −10 dB, 14.46 GHz (3.54–18 GHz) at a thickness of 1.0–5.5 mm], when the filler ratio is only 9 wt %. The excellent microwave absorption property is attributed to the abundant heterogeneous interfaces and carbon defects, which collectively increase polarization loss. This work demonstrates that creating heterogeneous interfaces and carbon defects through the construction of multicomponent electromagnetic composite materials with microstructures and multiheteroatom doping is an effective approach in designing efficient lightweight electromagnetic wave absorbers.