  In this work, density functional theory calculations were carried out to
explore the mechanical response, dynamical/thermal stability,
electronic/optical properties and photocatalytic features of monoclinic As2X3
(X=S, Se and Te) nanosheets. Acquired phonon dispersions and ab-initio
molecular dynamics results confirm the stability of studied nanomembranes.
Observation of relatively weak interlayer interactions suggests that the
exfoliation techniques can be potentially employed to fabricate nanomembranes
from their bulk counterparts. The studied nanosheets were found to show highly
anisotropic mechanical properties. Notably, new As2Te3 2D lattice predicted by
this study is found to exhibit unique superstretchability, which outperforms
other 2D materials. In addition, our results on the basis of HSE06 functional
reveal the indirect semiconducting electronic nature for the monolayer to
few-layer and bulk structures of As2X3, in which a moderate decreasing trend in
the band-gap by increasing the thickness can be established. The studied
nanomaterials were found to show remarkably high and anisotropic carrier
mobilities. Moreover, optical results show that these nanosheets can absorb the
visible light. In particular, the valence and conduction band edge positions,
high carrier mobilities and optical responses of As2Se3 nanosheets were found
to be highly desirable for the solar water splitting. The comprehensive vision
provided by this study not only confirm the stability and highly attractive
electronic and optical characteristics of As2S3, As2Se3 and As2Te3 nanosheets,
but also offer new possibilities to design superstretchable nanodevices.

Computational Physics;Materials Science