Lifting of the Au(100) surface reconstruction by Pt, Cr, Fe, and Cu adsorption

Abstract

The adsorption and growth of metals on the surfaces of other metals is an important topic for studies of heterogeneous catalysis and bimetallic nanoparticles. The surface structure of these systems impacts nanoparticle growth, catalytic activity, and reaction selectivity. In these experiments, platinum, chromium, iron, or copper were vapor deposited on the reconstructed Au(100) surface. The initial growth of each metal was studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Each of the four metals form anisotropic rectangular islands oriented in the direction of the gold reconstruction rows. The gradual lifting of the surface reconstruction by increased metal coverage is observed, and the reconstruction is fully lifted after 0.5 ML of Pt, Cr, or Fe, or by 3.3 ML of Cu. After the reconstruction is lifted, the island shape changes from rectangular to square, illustrating the effect of surface structure on growth. Second layer islands begin to form before the completion of the first full layer.

Redox-active ligand controlled selectivity of vanadium oxidation on Au(100)

“… 57 – 59 One effect of this well-characterized reconstruction is a periodic variation in the heights of the Au atoms or “rows”, which lead to anisotropy in the growth of metal islands on this surface. 58 Vanadium grows on Au(100) at submonolayer coverages as flat, rectangular nanoislands that are oriented in the direction of the row features created by the surface reconstruction ( Fig. 1d ), similar to the growth of other metals on the same surface.…”

“…1d ), similar to the growth of other metals on the same surface. 58 The average height of these islands is 2.3 ± 0.2 Å. XPS shows that the V in these islands is in a zero oxidation state ( Fig. 1a ).…”

Redox Isomeric Surface Structures Are Preferred over Odd‐Electron Pt1+

“…Before discussing the coordination structure of Pt and BMTZ on the Au(100) surface, it is necessary to first consider the structures of Pt and BMTZ individually on the surface. As discussed in previous works, Pt forms two‐dimensional rectangular islands where the long axis of the islands is parallel to rows formed on the surface as a result of the hexagonal c(26×68) surface reconstruction of the Au(100) (Figure a). On the other hand, at submonolayer coverages, BMTZ does not form a stable, self‐assembled structure that we could image by STM, indicating a weakly bound state that is either mobile on the timescale of STM or easily displaced by the scanning probe.…”

“…[15,21] This is well below the binding energy of 75.7-76.0 eV reportedf or Pt 4 + complexes. [22] We note that the Pt 4f 7/2 positionf or as ub-monolayer quantity of Pt (no ligand present) on the Au(100) surface (70.6 eV) [18] was used as ar eference point for Pt 0 herea st his shows as light shift from the BE for bulk Pt (71.2 eV) [23] due to final state effects in proximity to the Au surface. [24] The Pt II chemical state indicated by as hift in the Pt 4f XPS peak positionr esults from on-surface charge transfer with the electron-acceptingt etrazine ring.…”

Protection of one-dimensional Si chains embedded in Pt(111) and protected by a hexagonal boron-nitride monolayer

“…On the other hand, the driving force of the densification can be mitigated by adsorbates on top, which provide additional electron density. Indeed, lifting of surface dislocation networks has been observed for several adsorbates [10][11][12][13]. Consequently, the created 1D structures are typically quite fragile even under ultrahigh vacuum (UHV) conditions.…”