A novel rod-like MnO2@Fe loading on graphene giving excellent electromagnetic absorption properties

Abstract

Impedance matching and the attenuation constant, α, are two key parameters in determining electromagnetic absorption properties. Although materials with single magnetic or dielectric loss properties have a high α value, they nonetheless suffer from poor impedance matching. The design of magnetic and dielectric composites might possibly be an effective method of solving this problem, but unfortunately the introduction of magnetic material may give a poor value of α. In order to obtain absorptive materials with high impedance matching and a high value of α, we have designed a novel ternary composite of MnO₂@Fe–graphene. A 30 nm wide rod-like strip of MnO₂ was first obtained by a simple liquid process. Liquid decomposition of Fe(CO)₅ was then carried out to deposit iron on the surface of the rod-like structure, and the MnO₂@Fe was finally loaded on graphene by a liquid deposition technique. The resulting ternary composite exhibited attractive electromagnetic absorption properties, in which the optimal reflection loss of up to −17.5 dB obtained with a thin coating thickness of 1.5 mm was able to satisfy the requirements of lightness of weight and a high degree of absorption. The effective bandwidth frequency of MnO₂@Fe–GNS is broader than that of pure MnO₂ or MnO₂@Fe, possibly due to its moderate impedance matching and attenuation ability. The possible attenuation mechanism will also be discussed.