Two-dimensional Ti2 C monolayer (MXene): surface functionalization, induced metal, semiconductor transition

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