▎ 摘　　要

The ZnO-doped magnetic graphene composite materials were prepared by a two-step hydrothermal method. The microstructures and compositions were characterized by scanning electron microscope, transmission electron microscope, X-ray diffractometer, and X-ray photoelectron spectroscopy. The electromagnetic properties were determined by vector network analyzer and vibrating sample magnetometer. The strengthening mechanism of absorbing properties was analyzed in combination with first-principles calculations. The results show that the ZnO sheets and Fe3O4 balls closely overlap under the ball-sheet and ball-ball interactions and form abundant micro-interfaces and cavity structures, enhancing the microwave absorbing property. The composite absorbing material reaches the minimum reflection loss of - 53.96 dB at 8.96 GHz with a thickness of 1.81 mm, and the effective absorbing band could be tun-able flexibly within the range of 5.2 - 18 GHz by adjusting the matching thickness within the range of 0.84 - 3.03 mm. First-principles calculations further demonstrate that the modification of ZnO greatly changes the electronic state and structure, reduces the energy barrier of electrons transferring, forms special charge transferring channels, increases the concentration of carriers, and improves the absorbing capacity of the material.