In situ formation of Fe3O4/N-doped carbon coating on the surface of carbon fiber with improved electromagnetic wave-absorption property

Carbon fiber is an absorbing material with high strength, acid and alkali resistance, high temperature resistance, flexibility, and processability and plays an important role in the electromagnetic (EM) wave absorption of civil buildings and military equipment. However, its EM wave-absorption performance is poor because of its large complex permittivity and no magnetic loss ability. In this study, dopamine hydrochloride and FeCl3 were used as precursors, and the Fe3O4/N-doped carbon coating was successfully grown in situ on the surface of short carbon fiber (SCF) via dopamine deposition, autopolymerization, FeCl3 solution immersion, and calcination at high temperature to improve its EM wave-absorption property. The obtained Fe3O4/N-doped carbon particles were uniformly attached to the SCF in the form of a thin layer to constitute a unique hierarchical structure. The Fe3O4/N-doped carbon coating/SCF displayed an excellent EM wave-absorption performance. An effective bandwidth of 8.64 GHz and lowest reflection loss of −31.38 dB at 3 mm were achieved because of the significant reduction in complex permittivity and improvement in complex permeability, wave impedance, and EM loss ability of the SCF. The Fe3O4/N-doped carbon coating is expected to show great potential in EM wave-absorption fields.