# Mechanistic insights on the phosphorene degradation

## TL;DR

This study provides detailed mechanistic insights into the structural and chemical degradation processes of phosphorene, using first-principles calculations to develop a comprehensive degradation phase diagram and identify key atomic-level mechanisms.

## Contribution

It introduces a first-principles based phase diagram for phosphorene degradation, elucidating microscopic kinetic pathways and temperature effects on structural and chemical stability.

## Key findings

- Degradation involves vacancy merger and annihilation at 400 K.
- Structural degradation occurs via atom emission and sublimation above 650 K.
- Chemical degradation is driven by oxygen dissociation at defect sites.

## Abstract

The structural and chemical degradations of phosphorene severely limit its practical applications despite the enormous promise. In this regard, we investigate a plethora of microscopic kinetic mechanisms and develop a degradation phase diagram within the first-principles calculations. At 400 K, the degradation and the competing self-annealing proceeds through the merger and annihilation of vacancies, respectively, which are triggered via itinerant vacancy and adatom. A further increase in temperature beyond 650 K, the structural degradation results through the emission of the undercoordinated atoms from the defect and the concurrent pair-wise sublimation. The role of inter-layer vacancy diffusion is discarded in the context of structural degradation. The chemical degradation is routed through the dissociation of oxygen molecule that is either activated at the room-temperature on the pristine surface or spontaneous at the single-vacancy site. The present results are in agreement with the few available experimental conjectures and will motivate further efforts.