Atomic-Scale View of Redox-Induced Reversible Changes to a Metal-Oxide Catalytic Surface: VOx/α-Fe2O3(0001)

Abstract

X-ray standing wave (XSW) analysis and X-ray photoelectron spectroscopy are used to trace the electronic and atomic-scale structural changes of a supported vanadium oxide system at different stages of its oxidation−reduction cycle. Both the oxidation state and adsorption geometry of the vanadium oxide and its α-Fe2O3(0001) single crystal support show reversible changes through the oxidation−reduction cycle characteristic of catalytic behavior. The 3D V atomic distribution maps, derived from the summation of the XSW measured Fourier components, reveal that the V undergoes adsorption site exchange during the oxidation and reduction cycle.