Oxygen Vacancies in the Single Layer of Ti₂CO₂ MXene: Effects of Gating Voltage, Mechanical Strain, and Atomic Impurities

Abstract

Herein, using first‐principles calculations the structural and electronic properties of the Ti2CO2 MXene monolayer with and without oxygen vacancies are systematically investigated with different defect concentrations and patterns, including partial, linear, local, and hexagonal types. The Ti2CO2 monolayer is found to be a semiconductor with a bandgap of 0.35 eV. The introduction of oxygen vacancies tends to increase the bandgap and leads to electronic phase transitions from nonmagnetic semiconductors to half‐metals. Moreover, the semiconducting characteristic of O‐vacancy Ti2CO2 can be adjusted via electric fields, strain, and F‐atom substitution. In particular, an electric field can be used to alter the nonmagnetic semiconductor of O‐vacancy Ti2CO2 into a magnetic one or into a half‐metal, whereas the electronic phase transition from a semiconductor to metal can be achieved by applying strain and F‐atom substitution. The results provide a useful guide for practical applications of O‐vacancy Ti2CO2 monolayers in nanoelectronic and spinstronic nanodevices.

Tunable electronic and magnetic properties of MoSi2N4 monolayer via vacancy defects, atomic adsorption and atomic doping

“…Common defects such as the monovacancy, divacancy, Stone Wales [24][25][26], antisite, substitution, adatom, heterostructures [27], charged impurities [28][29][30], and grain boundary have been observed in the 2DMs [31,32]. They have a larger impact on the electronic and optical properties of 2D materials [33][34][35]. Defects can play different roles such as carrier donors, scattering, trapping, and recombination centers [36][37][38][39].…”

Prospective advances in MXene inks: screen printable sediments for flexible micro-supercapacitor applications

“…Additionally, the T x or IC functionalities are capable of changing the nature of a MXene. For example, it has been illustrated that the full functionalization of Ti 2 C MXene nanosheets with O can convert the metallic nature of Ti 2 C to a semiconductor state with a bandgap of 0.34 eV and a great Seebeck coefficient of ∼1140 μV K −1 at 100 K. 41 This phenomenon is due to the strong hybridization of Ti-d and O-p orbitals. 41…”

Structure-activity correlation of Ti2CT2 MXenes for C–H activation

“…For instance, the O termination always increases the work function while the OH termination would decrease it [33]. Furthermore, the configuration and defects of termination groups including O-vacancy not only tune the electronic structure but also enhance the catalytic activity [34]. Therefore, it is crucial to study how termination groups influence the property of MXenes as well as to explore the correlation between the termination configuration and the catalytic performance of the catalyst.…”