Rapid oxygen exchange between hematite and water vapor

Abstract

Oxygen exchange at oxide/liquid and oxide/gas interfaces is important in technology and environmental studies, as it is closely linked to both catalytic activity and material degradation. The atomic-scale details are mostly unknown, however, and are often ascribed to poorly defined defects in the crystal lattice. Here we show that even thermodynamically stable, well-ordered surfaces can be surprisingly reactive. Specifically, we show that all the 3-fold coordinated lattice oxygen atoms on a defect-free single-crystalline r-cut (1-102) surface of hematite (α-Fe2O3) are exchanged with oxygen from surrounding water vapor within minutes at temperatures below 70 °C, while the atomic-scale surface structure is unperturbed by the process. A similar behavior is observed after liquid water exposure, but the experimental data clearly show most of the exchange happens during desorption of the final monolayer, not during immersion. Density functional theory computations show that the exchange can happen during on-surface diffusion, where the cost of the lattice oxygen extraction is compensated by the stability of an HO-HOH-OH complex. Such insights into lattice oxygen stability are highly relevant for many research fields ranging from catalysis and hydrogen production to geochemistry and paleoclimatology.

References in corpus (10)

• Van der Waals Density Functional for General Geometries
• Efficient implementation of a van der Waals density functional: Application to double-wall carbon nanotubes
• Phonon-phonon interactions in transition metals
• Subsurface Cation Vacancy Stabilization of the Magnetite (001) Surface
• Water Agglomerates on Fe3O4(001)
• An Atomic-Scale View of CO and H2 Oxidation on a Pt-Fe3O4 Model Catalyst
• A Multi-Technique Study of $C{O}_2$ Adsorption on $F{e}_3$$O_4$ Magnetite
• Self-limited Growth of an Oxyhydroxide Phase at the Fe3O4(001) Surface in Liquid and Ambient Pressure Water
• Apparatus for dosing liquid water in ultrahigh vacuum
• Insight into the interface between Fe${}_3$O${}_4$(001) surface and water overlayers through multiscale molecular dynamics simulations

Cited by in corpus (1)

• Digging its own Site: Linear Coordination Stabilizes a Pt1/Fe2O3 Single-Atom Catalyst