MXene-assisted construction of versatile cellulose-based aerogels with multilayered structure for piezoresistive sensing and contaminant adsorption

Developing a compressible, ultralight, conductive, and hydrophobic biomass-based aerogel with multifunctional characteristics is greatly desirable nowadays. Herein, cellulose nanofiber (CNF)/Ti₃C₂T_x (MXene)/polyvinyl alcohol (PVA) composite aerogels have been designed via a facile bidirectional freezing process, followed by chemical vapor deposition treatment. Benefiting from the porous architecture, chemical crosslinking and hydrogen-bonding between CNF, PVA and MXene, the aerogels exhibited oriented lamellar texture, endowing it with ultralow density, excellent compressibility, conductivity and recoverability. The polysiloxane coating imparted the aerogels outstanding hydrophobicity, contributing to an excellent capability for organic contaminants (e.g. N-hexane, cyclohexane, dichloromethane, chloroform, acetone, pump oil and edible oil) from water, including high adsorption capacity (30.43 to 167.00 g g^-1) and stable recyclability. Utilized as pressure sensors, these aerogels showed excellent sensing properties, including high sensitivity (2.41 kPa^-1), rapid response time (78 ms) and recovery time (83 ms), as well as exceptional detection ability for different human body movement information. It is expected that the fabricated composite aerogels will provide a new versatile platform for pressure signals detection and high-efficient organic contaminants adsorption.