Lightweight, Superelastic, and Hydrophobic Polyimide Nanofiber /MXene Composite Aerogel for Wearable Piezoresistive Sensor and Oil/Water Separation Applications

Abstract Inspired by the ultralight and structurally robust spider webs, flexible nanofibril‐assembled aerogels with intriguing attributes have been designed for achieving promising performances in various applications. Here, conductive polyimide nanofiber (PINF)/MXene composite aerogel with typical “layer‐strut” bracing hierarchical nanofibrous cellular structure has been developed via the freeze‐drying and thermal imidization process. Benefiting from the porous architecture and robust bonding between PINF and MXene, the PINF/MXene composite aerogel exhibits an ultralow density (9.98 mg cm −3 ), intriguing temperature tolerance from ‐50 to 250 °C, superior compressibility and recoverability (up to 90% strain), and excellent fatigue resistance over 1000 cycles. The composite aerogel can be used as a piezoresistive sensor, with an outstanding sensing capacity up to 90% strain (corresponding 85.21 kPa), ultralow detection limit of 0.5% strain (corresponding 0.01 kPa), robust fatigue resistance over 1000 cycles, excellent piezoresistive stability and reproductivity in extremely harsh environments. Furthermore, the composite aerogel also exhibits superior oil/water separation properties such as high adsorption capacity (55.85 to 135.29 g g −1 ) and stable recyclability due to its hydrophobicity and robust hierarchical porous structure. It is expected that the designed PINF/MXene composite aerogel can supply a new multifunctional platform for human bodily motion/physical signals detection and high‐efficient oil/water separation.