MXenes-Based Functional Fibers and Their Applications in the Intelligent Wearable Field

Abstract: Technological advances such as electronic information and the Internet of Things have increased the daily use and demand for wearable electronic devices and intelligent fabrics. This has led to an unprecedented development of functional fibers, the properties of which are largely determined by their basic building blocks. Transitional metal carbon/nitrogen compounds (MXenes) are an emerging class of two-dimensional materials that have been widely used in many wearable devices owing to their high electrical conductivity, excellent processability, tunable surface properties, and outstanding mechanical strength. In this paper, we summarize the various synthetic methods for MXenes materials. Moreover, we also compare the characteristics of the different preparation techniques and elaborate the mechanical, electrical, optical, and chemical stability properties of the materials. This paper primarily focuses on the surface terminal groups of MXenes and the effect they have on different properties. At present, various methods have been developed for the preparation of MXenes-functionalized fibers, including pasting MXenes on the surface of matrix fibers by coating and producing solid fibers from a slurry containing MXenes by wet spinning or electrospinning. Among them, wet spinning has been the most widely adopted method, and is very promising for the large-scale production of MXenes-functionalized fibers. This paper also summarizes the properties of functional fibers obtained by various preparation methods. Furthermore, functional fibers prepared by different processes have been applied several fields, including flexible energy storage devices, wearable sensors, wires for electrical signal transmission and conversion, and integration of multifunctional intelligent fabrics. Great progress has been made in the research of supercapacitors and sensors with MXenes-functionalized fibers as electrodes which are anticipated to be integrated into intelligent textiles. This paper summarizes the potential applications of MXenes-functionalized fibers and reports on the challenges that must be addressed before practical applications can be realized. Firstly, a fluorine-free preparation of MXenes materials must be achieved whilst improving yields. Secondly, tunability of the functional groups on the surface of MXenes materials must be attained. Lastly, an improvement to the long-term chemical stability of MXenes in the environment should be accomplished. While efficiently obtaining high-quality MXenes materials, it is equally important to develop new MXenes-functionalized fiber preparation techniques. Furthermore, the potential applications of MXenes-functionalized fibers could be broadened by developing new fiber weaving processes. We finally summarize the potential applications of intelligent fabrics based on MXenes-functionalized fibers. Whilst challenges remain, MXenes are an emerging family of two-dimensional materials with many attractive properties and many potential applications worth exploring.