Manipulation of microstructure of MXene aerogel via metal ions-initiated gelation for electromagnetic wave absorption.

[Display omitted] • MXene aerogels have been successfully fabricated by ions-initiated gelation. • MXene aerogels exhibit superior EMW absorption performance due to good impedance matching. • The broad EAB of 7.12 GHz can be attained for MXene aerogel. MXene aerogels with 3D network structure have gained much attention as lightweight electromagnetic wave (EMW) absorbers. It is still challenging to construct MXene aerogel monoliths with excellent EMW absorption capability in a simple way. Herein, the assembly of MXene aerogels was realized by gelation initiated by various metal ions in an aqueous dispersion, where metal ions link the MXene sheets together by bonding with OH groups on the MXene surface. It is found that metal ions have a great influence on the assembly microstructures of MXene aerogels, which are closely related with the complex permittivity of MXene aerogel absorbers. Versus divalent metal ions, MXene aerogels assembled with trivalent metal ions possess relative lower complex permittivity and deliver superior EMW absorption performance. Typically, a broadest EAB of 7.12 GHz can be achieved by MX-Fe3+, ascribing to its good impedance matching and multiple dissipation modes. Overall, this work provides an effective way to fabricate MXene-based aerogels to satisfy the lightweight requirement of future high-performance EMW absorption materials. [ABSTRACT FROM AUTHOR]