Multifunctional, superhydrophobic and highly elastic MXene/bacterial cellulose hybrid aerogels enabled via silylation

Abstract

Endowing MXene-based electromagnetic wave-shielding aerogels with superior hydrophobicity and reversible compressibility is crucial, yet challenging to support their adaptability to humid surroundings and reliability. From an economic and environmental perspective, it is highly desired to devise a practical method to fabricate such aerogels derived from MXenes and biomass. Herein, methyltrimethoxysilane (MTMS)-treated bacterial cellulose (BC) and Ti₃C₂T_x MXene suspensions are unidirectionally freeze-dried to prepare silylated BC/MXene aerogels. The hybrid aerogel with 84 wt% MXene integrates superior hydrophobicity (water contact angle of 128°), high elasticity (residual height of 87.5% after 100 compression cycles), and high electrical conductivity of 132 S m⁻¹. Silylation treatment can boost electromagnetic interference (EMI) shielding efficiency (SE) by ∼25%. The specific electromagnetic interference (EMI) shielding effectiveness (SE) of the aerogel reaches 66 943.8 dB cm² g⁻¹, significantly outperforming that of other shielding materials. An increasing silylated BC (S@BC) content enables a significant enhancement in the hydrophobicity, aerogel elasticity, and compressive strength. When the S@BC loading was up to 50%, the mechanically robust and highly elastic aerogel exhibited superhydrophobic behavior while offering 99.6% shielding of electromagnetic waves (23 dB). The silylation treatment also enriches the diversity of the aerogel applications such as self-cleaning, strong adsorption of organic solvents and oils, efficient thermal insulation, and sensitive strain–electrical signal response.