Hollow engineering of Co/N-doped C@carbon aerogel with hierarchical structure boosting interfacial polarization for ultra-thin microwave absorption and thermal insulation

Rational manipulation of the composition and microstructure design of aerogel materials is considered to be an effective method for achieving the dual functions of microwave absorption and thermal insulation. Herein, hollow Co/N-doped C@carbon aerogel with hierarchical structures was designed and constructed via a synergistic strategy including directed freeze-drying, ZIF-67 in situ growth, chemical etching and calcination treatment. Co/N-doped hollow carbon nanocages derived from ZIF-67 with uniform heterojunctions and layered micro-mesopores were constructed using tannic acid and heat treatment process. After that, abundant macroporous structure from the carbon aerogel itself was further introduced to upgrade the impedance matching property, light weight and interfacial polarization loss capability. Remarkably, as-fabricated Co/N-doped C@carbon aerogel (ZTA@A-900) displays optimal MA performance with a minimum reflection loss (RL_min) value of −54.0 dB at 15.32 GHz and a broad effective absorption bandwidth (EAB) of 4.04 GHz (13.44–17.48 GHz) at a thickness of only 1.4 mm. Furthermore, the ideal CST simulation results and excellent thermal insulation property of ZTA@A-900 make it an outstanding candidate for microwave absorbers under extreme conditions. Thus, our work opens up a new avenue for the design and fabrication of multifunctional lightweight microwave absorbers.