Theoretical Studies on the Modulation of the Electronic Property of Ti2CO2 by Electric Field, Strain, and Charge States

As a new two-dimensional transition metal carbides, MXene has various potential applications, such as energy storage, catalyst, composite material, and luminescent materials for their excellent physical and chemical properties. The element doping, geometrical defect, surficial functionalization, external electric field, and external strain can be used as effective methods for modulation of their properties. Ti2CO2, the thinnest Ti-based MXene, exhibits semiconducting character. The effects of electric field on the band structure of perfect primitive Ti2CO2 were explored in this work. The results revealed that the band gap of perfect primitive Ti2CO2 decreased with the increasing electric field. Carbon (C) vacancy in Ti(2)CO(2 )MXene was easily produced during the preparation process. Further investigation showed that the tensile strain could be used to regulate the conductivity of this system as the bands around the Fermi energy become smoother with increasing tensile strain. The investigation of charged C vacancy doped 2x2x1 Ti2CO2 indicated that its Fermi energy decreased with the increase of charge state. When it was +2 charged, the C vacancy doped 2x2x1 Ti2CO2 exhibited semiconducting character and owned a direct band gap of 0.489 eV.