Electronic and Optical Properties of 2D Transition Metal Carbides and Nitrides (MXenes)

2D transition metal carbides, carbonitrides, and nitrides, known as MXenes, are a rapidly growing family of 2D materials with close to 30 members experimentally synthesized, and dozens more studied theoretically. The discovery of 2D titanium carbide in 2011 added a new family of materials known as MXenes to the 2D world. MXenes produced from chemical etching are always terminated by O, OH, F or more likely, a combination of all species. For electronic and optical studies, large lateral-size and high-quality MXene flakes are preferable. Electronic properties of MXenes such as metal-to-insulator transition, ultralow work function, topological insulator, large electronic anisotropy, and massless Dirac dispersion near the Fermi level have been extensively investigated computationally. High electronic conductivity of MXenes makes them promising in many applications, such as EMI shielding, electrode materials in batteries and supercapacitors, transparent conductors, and conductive fillers.