Two-dimensional Ti₂C monolayer (MXene): surface functionalization, induced metal, semiconductor transition

Authors: BERNA AKGENC

Abstract: 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 Ti₂C and fully surface terminated Ti₂ CT₂ (T = -F, = O, -OH) are calculated using a set of first principles calculations. The ground state structures of Ti₂ CT₂ are computed in two and four different configurations for both H and T phases, respectively. We demonstrate that while H phase of Ti₂C exhibits half-metallic behavior with magnetic moments of 2 μB per formula unit, it displays metallic behavior with magnetic moments of 1.27 μB , 0.25 ?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 Ti₂C exhibits metallic behavior with magnetic moment of 1.89 μB 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.

Keywords: 2D materials, density functional theory, MXenes, Ti₂C, electronic and magnetic properties, surface functionalization

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