Lightweight N-Doped Carbon Aerogels Decorated with Magnetic CoNi Alloy Particles for Broadband Electromagnetic Wave Absorption and Thermal Insulation

The development of lightweight, multi-functional, broadband and high-efficiency electromagnetic wave absorption (EWA) materials remains a major challenge at present. In this work, chitosan-derived N-doped magnetic CoNi-decorated carbon aerogels were successfully fabricated by directional freezing and subsequent carbonization process. The constructed directional porous structure and the CoNi-decorated N-doped carbon hetero-interface optimize the impedance matching by regulating polarization, conductivity and magnetic loss. This is achieved by precisely controlling the degree of graphitization and the loading amount of CoNi alloy particles. Meanwhile, the directional porous framework is benefit for improving multiple reflections and scattering of electromagnetic wave. Remarkably, the fabricated N-Doped carbon aerogels decorated with CoNi alloy particles (CsCN-2) displays optimal EWA performance at low density (0.067 g/cm 3 ) with a minimum reflection loss (RL min ) value of -58.81 dB at 12.80 GHz, and a broad effective absorption bandwidth (EAB) could reach 6.96 GHz with thickness of only 3.09 mm. Moreover, when the thickness is reduced to 2.85 mm, the maximum EAB can expand to 7.52 GHz (from 10.48 GHz to 18 GHz). In addition, the CsCN-2 carbon aerogels also achieve excellent CST simulation results and outstanding thermal insulation. This work presents a novel insight for designing multifunctional carbon aerogels with high-performance of EWA.