Abstract:

The fabrication of high-performance electromagnetic (EM) wave absorption (EMA) materials is an effective strategy to deal with ever-increasing EM pollution. In this work, a series of manganese oxides/porous carbon (Mn_xO_y@C) hybrid composites are obtained by a two-step process. It is revealed that different manganese oxides play various influence on the dielectric properties of absorbers. Owing to the moderate complex permittivity of MnO@C hybrid composites, the optimal reflection loss could reach as high as -76.0 dB at the matching thickness of 2.0 mm with 5.2 GHz of effective absorption bandwidth at thickness of 2.1 mm. We demonstrated that the addition of porous carbon is vital for enhancing EMA performance of composites, which not only coordinates impedance matching allowing more EM waves enter the absorber, but also provides the path for electron movement, thus profiting conductive loss. Besides, different heterogeneous interfaces including porous carbon, manganese oxide and so on, are conducive to contribution of interface polarization. The most noteworthy is ingenious design of composite materials and systematic research of EM energy attenuation mechanism in this work will provide the possibility to realize high-performance EMA.

Key words: Manganese oxide/carbon composites, Dielectric loss, Relaxation time, Electromagnetic wave absorption