Dissociative chemisorption pathways of oxygen on Nb(100) surface: A first-principles study

We investigate the dissociative chemisorption of O₂ on the Nb(100) surface using real-space density functional theory. We show that the adsorption process is governed by electrostatic interactions at large O₂-Nb separations, with a preference for the atop site before gradually moving toward the bridge or bridge/hollow site. As the separation decreases below 1.3 Å, O₂ fully shifts to the bridge/hollow site, triggering dissociation. We map the chemisorption channels, analyze the charge transfer, and assess the bond polarity, providing insights into Nb's oxidation mechanism. This understanding lays the foundation for studying oxidation processes and offers potential strategies to mitigate or enhance oxidation in Nb-based materials and devices.