Synthesis of lightweight, hierarchical cabbage-like composites as superior electromagnetic wave absorbent

Three-dimensional (3D) hierarchical cabbage-like carbonaceous materials (Fe/CCMs- X , X means treating temperature) have been successfully prepared employing combinatorial processes of cobalt-assisted hydrothermal carbonization (HTC) of furfural and subsequent iron salt impregnation and thermal treatment. This new absorbent was characterized using powder X-ray diffraction (XRD), N 2 adsorption–desorption isotherms, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM) techniques. The maximum reflection loss (RL) of Fe/CCMs-500 reached −22.9   dB, and the effective absorption bandwidth (RL   ⩽   −10   dB) was 4.32   GHz (7.76–9.84   GHz and 11.20–13.44   GHz) corresponding to an absorber thickness of 2.5   mm, a low loading amount of iron (6.83%) component and high carbon content (69.8%), clearly demonstrating its wide absorption frequency range and strong absorption ability. It is thus believed that the newly synthesized Fe/CCMs-500 can serve as light-weight electromagnetic wave absorbent and can be potentially used in practice.