Controllable synthesis of porous Fe3O4@ZnO sphere decorated graphene for extraordinary electromagnetic wave absorption

Abstract

For the first time, mesoporous Fe₃O₄@ZnO sphere decorated graphene (GN–pFe₃O₄@ZnO) composites with uniform size, considerable porosity, high magnetization and extraordinary electromagnetic (EM) wave absorption properties were synthesized by a simple and efficient three-step method. Structure and morphology details were characterized by X-ray diffraction, transmission electron microscopy, high-resolution electron microscopy and field-emission scanning electron microscopy. Electron microscopy images reveal that pFe₃O₄@ZnO spheres with obvious porous and core–shell structures are uniformly coated on both sides of the GN sheets without significant numbers of vacancies or apparent aggregation. EM wave absorption properties of epoxy containing 30 wt% GN–pFe₃O₄@ZnO were investigated at room temperature in the frequency region of 0.2–18 GHz. The absorption bandwidth with reflection loss (RL) values less than −10 dB is up to 11.4 GHz, and the minimal RL is almost −40 dB. The intrinsic physical and chemical properties of the materials, the synergy of Fe₃O₄ and ZnO, and particularly the unique multi-interfaces are fundamental to the enhancement of EM absorption properties. The as-prepared GN–pFe₃O₄@ZnO composites are shown to be lightweight, have strong absorption, and broad frequency bandwidth EM absorbers.