C and S induces changes in the electronic and geometric structure of Pd(533) and Pd(320)

TL;DR

This study uses ab initio calculations to analyze how carbon and sulfur adsorption alter the electronic and geometric structures of Pd(533) and Pd(320) surfaces, revealing significant perturbations and potential catalytic poisoning effects.

Contribution

It provides detailed insights into the atomic-level effects of C and S adsorption on specific Pd vicinal surfaces, highlighting the local nature of these modifications.

Findings

Adsorption energies range from 5.31eV to 8.58eV for C and 2.89eV to 5.40eV for S.

Adsorbates cause large band splitting and reduce electronic states at the Fermi level.

C can penetrate surface to form subsurface structures.

Abstract

We have performed ab initio electronic structure calculations of C and S adsorption on two vicinal surfaces of Pd with different terrace geometry and width. We find both adsorbates to induce a significant perturbation of the surface electronic and geometric structure of Pd(533) and Pd(320). In particular C adsorbed at the bridge site at the edge of a Pd chain in Pd(320) is found to penetrate the surface to form a sub-surface structure. The adsorption energies show almost linear dependence on the number of adsorbate-metal bonds, and lie in the ranges of 5.31eV to 8.58eV for C and 2.89eV to 5.40eV for S. A strong hybridization between adsorbate and surface electronic states causes a large splitting of the bands leading to a drastic decrease in the local densities of electronic states at the Fermi-level for Pd surface atoms neighboring the adsorbate which may poison catalytic activity of the surface. Comparison of the results for Pd(533) with those obtained earlier for Pd(211) suggests the local character of the impact of the adsorbate on the geometric and electronic structures of Pd surfaces.