Structure of rhenium surfaces in an oxygen environment

Abstract

Using density functional theory in conjunction with thermodynamic considerations, we studied different clean and oxygen-covered Re surfaces: low-index Re(0001), Re(10$\overline{1}$0), Re(10$\overline{1}$1), and Re(11$\overline{2}$1) as well as high-index Re(13$\overline{4}$2), all surfaces that were found to be relevant in oxygen-induced surface faceting of rhenium. We found that on more open surfaces oxygen adsorption begins at lower oxygen chemical potentials, which can be correlated to the stronger O--surface interaction. Furthermore, at high-oxygen coverages close-packed Re(0001) becomes significantly more stable than the other Re surfaces that have been investigated. In addition to the stability of surface structures, we also provide quantitative information on the geometries and binding energies, which are of relevance for understanding the properties and catalytic behavior of Re-based catalysts operating under oxygen-rich conditions.