Lightweight MXene-Based Hybrid Aerogels with Ultrabroadband Terahertz Absorption and Anisotropic Strain Sensitivity.

MXene aerogels with a three-dimensional (3D) network structure have attracted increasing attention for lightweight electromagnetic wave absorbers. It is intriguing to expand their absorption band, i.e., to the booming terahertz (THz) region, and explore multifunctionality. Herein, we assemble MXene (Ti3C2Tx)-based hybrid aerogels into an aligned lamellar architecture using a bidirectional freezing technique. With air pore size and lamellar layer spacing comparable to THz wavelengths, high porosity of the aerogels allows nearly isotropic absorption of 99% and electromagnetic interference (EMI) shielding effectiveness with a remarkable value of 57.5 dB, in the ultrabroad bandwidth ranging from 0.5 to 3.0 THz. Simultaneous, strain-sensing response reflects the macroscopic anisotropy of the network structure of the aerogels. The improved sensitivity is measured for the out-of-lamellar layer plane under 0-30% strain. The corresponding long-term stability and durability persist over 120 stretching-releasing cycles. Our findings thus not only expand multiple functions of MXene in an anisotropic 3D macroscopic form but also clarify its nearly isotropic absorption in the THz band.