MXenes and their composites for energy storage and conversion

Abstract

After graphene, transition metals carbides, transition metal nitrides, and carbonitrides of two-dimensional family is also known as "MXene" gained more and more attention in the past few years especially because of their chemical and physical properties. Not only are MXenes and MXene-based composites used as energy storage devices and efficient conversion but they are very useful in environmental applications, water-splitting, photocatalysis, CO2 reduction, and sensors. This brief review provides complete details of MXene and MXene-based composites' behavior for various applications. This review provides details of hybrid MXene composite's progress such as energy storage and energy conservation. Because of electric double-layering and their mechanism of pseudocapacitive charge storage, MXenes are widely used in batteries and supercapacitors. MXenes can charge and discharge rapidly because of their unique chemistry and interlayer spacing. Moreover, MXenes have outstanding properties such as layered structures and the highest electrical conductivity. MXenes shows their ability far beyond any other kind of batteries and capacitors, even micro-supercapacitors. This chapter reviews fresh research on MXenes and MXene-based composites with small molecules; MXene mechanisms and thermoelectric properties, and electrochemical properties with various structural and fabrication methods are also described. MXenes' energy density and high mobility of two-dimensional materials are attributed to the internal surface of areas and large surface-area-to-volume ratio; thus these 2DMs can be used widely as electrodes in Li-ion batteries and supercapacitors. The energy storage application of MXenes depends on two-dimensional structures. MXenes and MXene-based composites are the best alternatives for this because of their excellent properties. For energy conservation and storage, various types of MXenes are synthesized because of their 2D structure and their higher absorption capacity amid a large surface area. This review helps us to understand the concept of MXenes as to why it has been used in conservation, storage, and environmental applications.