Exploring oxygen dissociation on hexagonal boron nitride: Insight from high-temperature molecular dynamics simulation

Hexagonal boron nitride (h-BN), known for its exceptional thermal and chemical stability, is widely used in high-temperature applications and as an encapsulation layer for other two-dimensional materials. This study examines the dissociation mechanisms of O₂ molecules on the h-BN surface, focusing on activation energies and minimum energy pathways at different adsorption sites using climbing-image nudged elastic band (CI-NEB) calculations. The results reveal several dissociation pathways with significant variations in activation barriers depending on site and configuration, including one low-barrier route favorable for surface reactions. Reactive molecular dynamics (RMD) simulations with the ReaxFF force field are employed to investigate oxidation behavior in multilayer h-BN at 900 K, 1200 K, and 1500 K. At 900 K, O₂ adsorbs without penetrating beneath the surface, while higher temperatures enhance dissociation and promote deeper oxygen incorporation. Charge analysis at elevated temperatures shows stronger chemisorption and electron transfer, forming a more uniform, chemically bonded oxygen layer.