Facile preparation of GNS/PyC@SiBCN aerogels with heterogeneous interfaces for broadband and tunable electromagnetic wave absorption

Carbon-based porous materials have been widely utilized for broadband electromagnetic wave absorption due to the versatility of carbon allotropes. In this study, a three-dimensional (3D) porous GNS/PyC@SiBCN aerogel has been innovatively developed with a unique heterogeneous structure, where the conductive network backbone composed of graphene nanosheets (GNS) and pyrolytic carbon (PyC) derived from cellulose is uniformly coated with the amorphous SiBCN ceramic. The dielectric and electromagnetic wave absorption properties of the aerogel can be precisely controlled by accurately regulating the content of GNS and the heat treatment temperature. Experimental results demonstrate that the aerogel exhibits broadband electromagnetic wave absorption performance in X band within a minimal thickness range of 3.27-3.5 mm, achieving a minimum reflection loss of -67 dB. The superior microwave absorption performance of the GNS/PyC@SiBCN aerogel composite is mainly attributed to the multiple electromagnetic wave loss mechanisms induced by its multi-scale structure. Notably, the enhanced interfacial polarization loss stemming from the heterogeneous structure offers novel perspectives for the advancement of high-performance electromagnetic wave absorption materials.