Flexible N-doped carbon fibers decorated with Cu/Cu₂O particles for excellent electromagnetic wave absorption

Flexible N-doped carbon fibers decorated with Cu/Cu₂O particles (NCF-Cu/Cu₂O) are synthesized through electrospinning, preoxidation and carbonization processes in this work. The characterization results indicate that HKUST-1 is embedded in polyacrylonitrile (PAN) fibers, and a special structure in which Cu/Cu₂O particles are strung together by carbon fibers is formed after preoxidation and carbonization. NCF-Cu/Cu₂O is mixed with paraffin in different mass ratios (5%, 10%, 15%, 20% and 25%) to study electromagnetic (EM) wave absorption performance at frequencies from 2.0 GHz to 18.0 GHz. When the filling ratio is 10%, the maximum reflection loss (RL) value is -50.54 dB at 14.16 GHz with a thickness of 2.4 mm, and the maximum effective absorption bandwidth (EAB) value reaches 7.2 GHz (10.8 ∼ 18.0 GHz) with a thickness of 2.6 mm. The NCF-Cu/Cu₂O composite fibers exhibit strong absorption, broad bandwidth, low filling ratio and thin thickness, and the corresponding absorption mechanism is analyzed in detail. The excellent EM wave absorption performance is attributed to a suitable attenuation ability, good impedance matching, conductive loss, interfacial polarization, dipole polarization, multiple reflections and scattering. This work provides a research reference for the application of flexible carbon-based composite fibers in the field of EM wave absorption.