The compositional dependence of structural stability and resulting properties for Mn+1CnT2 (M = Sc, Ti, V; T = O, OH, F, Cl, Br and I; n = 1, 2): first-principle investigations

Abstract

As a new type of two-dimensional layered carbides, nitrides or carbonitrides, MXenes have attracted widespread attention due to their excellent physical/chemical properties and huge potential functions. This work theoretically investigates the compositional dependence of Mn+1XnT2 and their electronic properties; where the series of Mn+1XnT2 (M = Sc, Ti, V; X = C; n = 1, 2; T = O, OH, F, Cl, Br, I) is employed as a case study. It is found that the Sc-based MXenes have the largest lattice constants, illustrating the weak interactions between the surface functionalized groups and Sc atoms. According to the mechanical stability analysis, it is found that except for Ti3C2O2, all the others are stable. Mechanically, the halogen functionalized (F, Cl, Br, and I) M2CT2 series have relatively large c11 values; and the Ti3C2Br2 has the largest c11 value. It is also found that the band gaps of Sc2CCl2 and Sc2CBr2 are 0.8734 and 0.6976 eV, respectively; both of which show their potential applications as indirect band gaps semiconductors.