Two-dimensional MXenes

The family of two-dimensional (2D) transition-metal carbides, carbonitrides, and nitrides, known as MXenes, has grown from a single composition in 2011 to a ~50-composition family. With a large number of possible transition metals and their combinations, four possible 2D thickness ranges for a single 2D flake, tunable surface chemistry and the capability for hosting species between their 2D flakes, MXenes can be considered one of the most amendable families of materials in the 2D space. MXenes have a unique combination of properties complementary to other 2D materials, such as high electrical conductivity (up to 24,000 S/cm), high Young’s modulus (reaching ~380 GPa), combined with 2D flexibility, and tunable and hydrophilic surfaces. These set of properties as well as their simple and scalable synthesis qualified MXenes to be studied in a variety of different areas, including energy storage and conversion, electrocatalysis, sensing, electromagnetic interference shielding and wireless communications, structural materials, tribology, environmental remediation, and biomedical fields. This issue covers the various MXene synthesis routes and some of MXenes emerging areas in sensing, environmental, and biomedical applications. Additionally, the structure, stability, and properties of MXenes are discussed from the computational studies perspective.