Enhanced Nanostructure Dynamics on Au(111) with Adsorbed Sulfur due to Au−S Complex Formation

Abstract

Chemisorbed species can enhance the fluxional dynamics of nanostructured metal surfaces which has implications for applications such as catalysis. Scanning tunneling microscopy studies at room temperature reveal that the presence of adsorbed sulfur (S) greatly enhances the decay rate of 2D Au islands in the vicinity of extended step edges on Au(111). This enhancement is already significant at S coverages, θS, of a few hundredths of a monolayer (ML), and is most pronounced for 0.1–0.3 ML where the decay rate is increased by a factor of around 30. For θS close to saturation at about 0.6 ML, sulfur induces pitting and reconstruction of the entire surface, and Au islands are stabilized. Enhanced coarsening at lower θS is attributed to the formation and diffusion across terraces of Au−S complexes, particularly AuS2 and Au4S4, with some lesser contribution from Au3S4. This picture is supported by density functional theory analysis of complex formation energies and diffusion barriers.

Electrocatalytic Reduction of Nitrogen to Ammonia: the Roles of Lattice O and N in Reduction at Vanadium Oxynitride Surfaces

“…In probing gas/surface interactions, surface-sensitive probes such as X-ray photoelectron spectroscopy (XPS) have been, for some time, a critical tool for understanding heterogeneous catalysis reaction mechanisms and for optimizing catalyst activity and selectivity. The corresponding studies at the electrolyte/solid interface are, however, a still-developing area of research. − With respect to vanadium oxynitrides, recent ex situ photoemission studies on vanadium nitride nanoparticles have shown that vanadium oxynitrides formed in situ are the active species and that an N surface state with an N 1s binding energy of 396.5 eV is associated with NRR activity. Moreover, the relative photoemission intensity of this feature correlated with the NRR activity of the nanoparticle .…”