Novel Electronic and Magnetic Properties of Two‐Dimensional Transition Metal Carbides and Nitrides

Abstract

Layered MAX phases are exfoliated into 2D single layers and multilayers, so‐called MXenes. Using first‐principles calculations, the formation and electronic properties of various MXene systems, M₂C (M = Sc, Ti, V, Cr, Zr, Nb, Ta) and M₂N (M = Ti, Cr, Zr) with surfaces chemically functionalized by F, OH, and O groups, are examined. Upon appropriate surface functionalization, Sc₂C, Ti₂C, Zr₂C, and Hf₂C MXenes are expected to become semiconductors. It is also derived theoretically that functionalized Cr₂C and Cr₂N MXenes are magnetic. Thermoelectric calculations based on the Boltzmann theory imply that semiconducting MXenes attain very large Seebeck coefficients at low temperatures.