Hydrothermal synthesis of magnetic Fe₃O₄/graphene composites with good electromagnetic microwave absorbing performances

The Fe₃O₄ sub-microspheres have been embedded uniformly into the reduced graphene oxide (rGO) to form a new-type Fe₃O₄/rGO composites through a one-pot solvothermal method. The dielectric properties for these magnetic Fe₃O₄/rGO composites can be greatly tuned by their different rGO additions. A good impedance matching from the balanced dielectric and magnetic loss is achieved in the Fe₃O₄/rGO composites with 4 wt% rGO addition, which dominates their excellent microwave absorbing performances including the minimum reflection loss (RL) value of −45 dB at a frequency of 8.96 GHz with a sample thickness of 3.5 mm and an effective absorption bandwidth of 3.2 GHz (below −10 dB) superior to those of the most magnetic materials and carbon-based composites. The controlled Fe₃O₄/rGO composite structure also exhibits high chemical stability and low density, which shows great potential application in high-performance electromagnetic microwave-absorbing materials.