Atomic Scale Insights into Reversible Oxygen Storage in Vanadium Oxide Thin Films

Abstract

Monolayer vanadium oxide films grown on Pt(111) supports can be reversibly switched between an oxygen‐poor and an oxygen‐rich composition, equivalent to V2O3 and V2O4.5, respectively. While the overall oxygen storage capacity of the film is quantified by X‐ray photoelectron spectroscopy, the atomic‐scale binding sites of the excess O species are determined by low‐temperature scanning tunneling microscopy and electron diffraction. In the O‐poor phase, the oxide takes the form of a honeycomb lattice that gets partially covered with vanadyl (V=O) groups at higher O exposure. Upon transition to the O‐rich phase, isolated V6O12 rings emerge first in the film, which then evolves gradually towards a disordered O‐V‐O trilayer on the Pt(111) surface. Our works thus unravels the microscopic nature of reversible oxygen storage in a model system for heterogeneous catalysis.