  Atom controlled sub-nanometer MoS$_2$ pores have been recently fabricated.
Oxidative environments are of particular interest for MoS$_2$ applications in
electronics, sensing and energy storage. In this work we carried out
first-principles calculations of oxygen adsorption in plain and sub-nanometer
MoS$_2$ nanopores. The chemical stability of the layers and pores towards
oxygen was verified using density-functional theory. Dissociation and diffusion
barriers have been calculated in order to understand surface and pore oxidation
and its electronic properties at the atomic scale, which opens the path for
future investigations of MoS$_2$ pores in a realistic environment.
