Computational studies on structural and electronic properties of functionalized MXene monolayers and nanotubes†
Abstract
MXenes, two-dimensional (2D) layered early transition metal carbide, nitride and carbonitride materials, have been prepared by exfoliating MAX phases. In addition to 2D planar MXene, one-dimensional tubular forms are also expected to form. Herein, we design atomic models for Sc2C monolayers and nanotubes as well as their functionalized counterparts, and investigate their stability and electronic properties through the density functional theory tight-binding method. Dramatic distortion of Sc2C and Sc2CO2 tubular structures occurs, while Sc2CH2 and Sc2C(OH)2 nanotubes preserve their tubular morphology upon structural relaxation. Moreover, we reveal that the radii of nanotubes play an important role in the relative stability and band gaps of tubular forms. Sc2CH2 and Sc2C(OH)2 nanotubes are direct-band-gap semiconductors, while the electronic structure of their corresponding planar forms depends on the arrangement of the functional groups.