Two-dimensional MXene-based flexible nanostructures for functional nanodevices: a review

Abstract

Two-dimensional MXenes have been extensively investigated in recent years and have resulted in the discovery of more than 30 compositions. The metallic conductivity and pseudocapacitive behavior of MXenes have demonstrated their exciting potential in electrochemical energy storage and conversion, electromagnetic shielding, wearable sensors, and personal thermotherapy. Driven by the surface termination functional groups, versatile chemistry, and outstanding solubility, MXenes have been integrated with various flexible and nanoporous substrates for wearable nanodevice applications. However, the available review mostly focuses on different substrates for multifunctional applications. No review intended for wearable nanodevices with a special focus on the breathability and comfort has been reported to date. In this review, we summarized the synthesis processes and their impact on MXene properties, and the structure–property relationship of MXenes. The current progress in MXene integration processes is comprehensively summarized and analyzed. We explored and evaluated the energy harvesting and storage, electromagnetic shielding, joule heating, as well as strain and pressure sensing applications. A brief overview of humidity and gas sensing of the MXene-based nanostructure is provided. Besides, the current challenges and perspectives in these burgeoning fields are highlighted for the development of wearable nanodevices.