First Principles Calculations of the Relative Stability, Structure and Electronic Properties of Two Dimensional Metal Carbides and Nitrides

Recently, a number of graphene-like early transition metal carbides and nitrides named asMXenes were fabricated by exfoliating MAX phases in hydrofluoric acid at room temperature. From experiments results and theory calculations, MXenes are promising anode materials in batteries as well as in metal-ion capacitors. To the best of our knowledge, experimental or calculated evidence has been supported the existence of more than 70 MAX phases members. Therefore, many counterparts MXene may be exist. Herein, employing density functional theory (DFT) computations, we have systematically examined the relative stability, structure and electronic properties of a series of two-dimensional metal carbides and nitrides including M2C (M= Sc, Ti, V, Cr, Zr, Nb, Hf, Mo and Ta), M2N (M= Ti, V, Cr, Zr, Hf), M3C2 (M= Ti, V, Nb, Ta), Ti3N2, M4C3 (M= Ti, V, Nb, Ta) and Ti4N3. The results demonstrate that all MXenes are metallic and have the similarly electronic structure with bulk transition metal carbides and nitrides, indicating that MXene may have superior catalysisand adsorption instead of expensive pure transition metal.