Preparation of graphene oxide based on microcrystalline graphite: the study of microwave absorption properties

Electromagnetic wave absorption materials play an increasingly important role in modern society for military stealth technology and 5G smart era. Microcrystalline graphene oxide (MGO) absorption materials have prepared by chemical oxidation method using microcrystalline graphite as raw material. The lamellar structure, functional groups, defects, and microwave absorption properties of MGO have characterized by X-ray diffractometer (XRD), Raman Spectrometer (Raman), Fourier Transform Infrared Spectrometer (FT-IR), Atomic Force Microscope (AFM), and Vector Network Analyzer (VNA). It is elucidated that the electromagnetic wave absorption mechanism of MGO. The results show that when the dosage of microcrystalline graphite is 1.0 g, the overall layer number of the MGO-1.0 is 1-2 layers, layer spacing is 0.900 nm, which exhibits the best microwave absorption properties, with its minimum reflection loss (RL_min) reaching -18.39 dB and its effective absorption band (EAB) is 3.06 GHz (7.97-11.03 GHz) at the microwave absorption layer thickness of 3.6 mm and the frequency of 9.42 GHz. This excellent microwave absorption properties is attributed to dipole polarization, defect polarization, and conductive loss. It is worth noting that the high conductivity, polar group, and edge defect density will cause the impedance mismatch of MGO and affect the microwave absorption properties.