Recent progress in thermoelectric MXene-based structures versus other 2D materials

Thermoelectricity is a next-generation solution for efficient waste heat management. Although various thermoelectric materials exist, there is still a lot of scope for advancement, especially in room temperature applications. Recently, two-dimensional (2D) materials, including MXenes, showed promise as thermoelectric materials. On the other hand, MXenes generally exhibit metallic behavior that can hinder thermoelectric performance. Nevertheless, the variety of MXene's chemical composition and surface functionalization facilitate the research path based on energy band engineering, carrier concentration, and mobility. Multiple strategies to enhance the thermoelectric properties of layered MXenes materials, including structural modifications, defects, band gap engineering, etc. have been comprehensively demonstrated. In addition, advanced structural engineering such as nanostructuring MXenes with materials of different dimensions, creating van der Waals heterostructures, alloying, and utilizing MXenes as nanoinclusions or nanocomposites is presented. The thermoelectric efficiency of MXenes over the landscape of other 2D and conventional thermoelectric materials has been systematically compared. Meanwhile, a future approach has been proposed to enhance the thermoelectric properties of novel members of the flatland, MBenes exhibiting an incredible diversity of structures and crystal symmetries. Finally, potential applications in thermoelectrics and future prospects of MXenes are discussed. This article provides a timely and unique review of MXenes' advantages and limitations that have never been so well understood and established. This creates a comfort zone for rational tailoring of their structure-property-performance relationship, which is crucial concerning the thermoelectric performance, widely covered in this review.