▎ 摘　　要

Unique covalently bonded cobalt ferrite (CoFe2O4)/graphene nanocomposites are successfully fabricated via an amino-ester-amide reaction process. The morphology, component, functional groups and electromagnetic properties are detected by Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectra (FTIR), Vibrating Sample Magnetometer (VSM) and Vector Network Analyzer (VNA). Compared to non-covalently bonded nanocomposites, the covalently bonded CoFe2O4/graphene nanocomposites have outstanding electromagnetic wave absorption properties. We found that the maximum reflection loss value reached at 55.2 dB and the absorption bandwidth with reflection loss below 10 dB was about 5.4 GHz at 1.7 mm of thickness. The efficiency is attributed to the introduction of amide bonds in the nanocomposites. As a stable carrier channel, amide bonds can promote the migration rate of electrons and binding degree between CoFe2O4 and graphene nanosheets, which provide a crucial impact on electromagnetic parameters and polarization modes of materials, thus improving the absorption capacity of electromagnetic waves. It can be inferred that the nanocomposites have a broad application prospect in the field of electronic instruments, aerospace, military radars and national defense security fields. (C) 2019 Elsevier Inc. All rights reserved.