Bi and Te adlayers on Pt(111), Pt(110), and Pt(100) surfaces: geometry and electronic structure

In this computational study the adsorption of bismuth and tellurium on platinum basal planes was studied by electronic structure calculations based on density functional theory. In a systematic approach the explicit interaction of Bi and Te with (111), (110), and (100) platinum surfaces was investigated, focusing on structural and electronic characteristics of the studied systems as a function of the adsorbate coverage. In case of more studied Bi/Pt systems, good agreement was found between calculated results and previously published data, both from experimental and theoretical studies. At lower coverages coadsorbed Bi and Te atoms interact repulsively with each. At the coverages close to half a monolayer, however, several factors affect the overlayers’ stability. On one hand, the downshift on the d-band centre of Pt atoms in contact to the adatom weakens the Pt-Bi(Te) bond; on the other hand, the depolarization of the contributes to their stabilization. As the result they remain stable in the whole range of coverages up to half a monolayer, maintaining a planar geometry. Overall, the obtained results evidence that Bi and Te adlayers supported on Pt cannot be treated as a mere combination of their parts and, instead, must be considered as unique materials with properties different from their parent systems. The results of present study were reviewed in the context of enhanced activity of Bi/Pt systems for the oxidation of organic molecules. It was proposed that, additionally to widely accepted third-body effects behind it, the electronic effects, such as Bi(Te)-induced work function lowering, charge redistribution and the d-band centre shift, play a significant role as well.