Synthesis of lightweight and flexible composite aerogel of mesoporous iron oxide threaded by carbon nanotubes for microwave absorption

Inorganic composites with mechanical flexibility are desired in synthesis of advanced materials for multifunctional applications. Here, we demonstrated the synthesis of a lightweight and flexible composite aerogel composed of carbon nanotubes (CNTs) and mesoporous iron oxide (Fe3O4) using an in-situ growth method. CNTs serve as frameworks for the growth of magnetic ferrite nanoparticles; while the growth of the magnetic nanoparticles crosslinks CNTs into an integrated structure. Therefore, mesoporous Fe3O4 particles are threaded by CNTs, leading to formation of the monolithic magnetic foam with a high particle loading of more than 88 wt%. This magnetic foam is highly porous, effective for microwave absorption. Based on the rational combination of Fe3O4 and CNTs, the composite material can offer excellent microwave absorbing performance, particularly in the low-frequency range of 3-5 GHz. Moreover, the porous composite aerogel can be compacted into a flexible magnetic nanopaper. Because of the structure properties, the composite may be used in many other applications such as energy storage, catalyst, and biochemistry.