Microwave-Driven Dielectric-Magnetic Regulation of Graphite@α-MnO2 Toward Enhanced Electromagnetic Wave Absorption.

Abstract

The advancement of wireless communication technologies necessitates materials that absorb electromagnetic waves and shield against electromagnetic interference. The research is propelled by the necessity to develop materials that possess both properties. Here, an electromagnetic wave-absorbing material that synergistically regulates dielectric and magnetic properties is developed. The material features a nanowire fabric/multilayer composite structure of expanded graphite@α-MnO₂ (EG@MO). The manganese oxide nanowires are prepared in situ on the surface of multilayer expanded graphite via microwave-assisted hydrothermal synthesis. A rapid microwave activation process is subsequently performed to convert manganese oxide-hydroxide, elevating its oxidation state, and transforming it from a non-magnetic form to the magnetic α-MnO₂. The EG@MO exhibits exceptional electromagnetic wave absorption capabilities, achieving a reflection loss value of -75.56 dB, with a low filler ratio of 7 wt.% and an ultrathin thickness of 1.48 mm. This high-performance electromagnetic absorption material, fabricated by integrating magnetic manganese dioxide nanowires with multilayer expanded graphite, shows excellent widespread applications.