Two-dimensional $Ti_2C$ monolayer (MXene): surface functionalization, induced metal, semiconductor transition

Abstract

Recently, two-dimensional (2D) transition metal carbides and nitrides known as MXenes, have gained a lotof attention because of their tunable electronic and magnetic properties depending on surface functionalization. In thepresent work, the structural, electronic, and magnetic properties of both T and H phases of bare Ti2 C and fully surfaceterminated Ti2 CT2 (T = -F, = O, -OH) are calculated using a set of first principles calculations. The ground statestructures of Ti2 CT2 are computed in two and four different configurations for both H and T phases, respectively. Wedemonstrate that while H phase of Ti2 C exhibits half-metallic behavior with magnetic moments of 2 ?B per formulaunit, it displays metallic behavior with magnetic moments of 1.27 ?B , 0.25 ?B per formula unit, and semiconductorbehavior with 0.35 eV band gap in -F, -OH, and =O surface functionalization, respectively. We also show that whileT phase of Ti2 C exhibits metallic behavior with magnetic moment of 1.89 ?B per formula unit, it stays in metallicnonmagnetic behavior in both -F and -OH. Meanwhile, it displays semiconductor behavior with 0.25 eV band gap in -Osurface functionalization. We expect that our results can advance the future applications of MXenes from energy storageto spintronic.