  Phosphorene is a promising two dimensional (2D) material with a direct band
gap, high carrier mobility, and anisotropic electronic properties.
Phosphorene-based electronic devices, however, are found to degrade upon
exposure to air. In this paper, we provide an atomic level understanding of
stability of phosphorene in terms of its interaction with O2 and H2O. The
results based on density functional theory together with first principles
molecular dynamics calculations show that O2 could spontaneously dissociate on
phosphorene at room temperature. H2O will not strongly interact with pristine
phosphorene, however, an exothermic reaction could occur if phosphorene is
first oxidized. The pathway of oxidation first followed by exothermic reaction
with water is the most likely route for the chemical degradation of the
phosphorene-based devices in air.
