In-Plane heterogeneous Structure-Boosted interfacial polarization in graphene for wide-band and wide-temperature microwave absorption

Theoretically, the strong permittivity dispersion characteristic of materials is essential for achieving broadband electromagnetic wave (EMW) absorption, which can be realized via amplified interfacial polarization effects between a dielectric phase and a lossy phase, such as by increasing the accumulated charge density in their interface area. Herein, we propose a novel strategy to boost interfacial polarization based on heterogeneous structure design in in-plane graphene (Gr) since the in-plane conductivity of Gr is significantly higher than its out-of-plane conductivity. To this end, Gr is grown on Si₃N₄ nanowires skeleton using chemical vapor deposition (CVD). Subsequently, Gr is controllably etched by Ni nanoparticles, and then, open graphite nanosteps are formed, which help construct in-plane heterogeneous interfaces between Gr and a dielectric phase. Such interfaces also help improve the impedance matching performance by disrupting the long-range conductive network of CVD-grown Gr. Notably, an effective absorption bandwidth of 8.48 GHz is achieved with a thickness of 2.85 mm, which is significantly wider than the EAB (5 GHz) of the out-of-plane heterogeneous structure. In addition, the in-plane heterogeneous structure also endows the EMW absorption material with excellent high-temperature insensitivity, realizing full-frequency absorption in the X-band in the 298–873 K range. This strategy to boost interfacial polarization via novel in-plane heterogeneous structure construction in Gr provides an alternative approach to explore the potential of Gr-based hybrids with planified structures to achieve wide-band and wide-temperature EMW absorption.