Synthesis of a hierarchical carbon fiber@cobalt ferrite@manganese dioxide composite and its application as a microwave absorber

In this study, a novel hierarchical carbon fiber@cobalt ferrite@manganese dioxide (CF@CoFe₂O₄@MnO₂) composite was facilely prepared via a sol-gel method and hydrothermal reaction. The morphology, structure, chemical and element composition, crystal form, elemental binding energy, magnetic behavior and microwave absorbing performance of the composite were carefully investigated. According to its hysteresis loops, the composite exhibits a typical soft magnetic behavior, with a M _s value of 30.2 emu g^-1. Besides, the as-synthesized CF@CoFe₂O₄@MnO₂ composite exhibits superior microwave absorption performance mainly due to reasonable electromagnetic matching, and its minimum reflection loss value can reach -34 dB with a sample thickness of just 1.5 mm. The composite can be regarded as an ideal microwave absorber.