Role of Gold Adatoms in the Adsorption of Sulfide Species on the Gold(001)-hex Surface

Abstract

We have studied the adsorption of reduced sulfur species on the Au(001)-hex surface from diluted ethanolic sulfide solutions by STM, XPS, electrochemical techniques and DFT calculations. Our results reveal the absence of S multilayers because all S species are bonded to Au surface atoms. Monomeric S adsorbs at hollow sites forming a (2×2) lattice, while S 2 species either capture the gold adatoms (Au ad) that result from the hex lifting or remove Au ad from the substrate forming well-ordered S 8-like structures. These are formed by four S 2 species coordinated by a central Au ad , with AuSS interatomic distances closely resembling those of a metal disulfide. Our results explain not only the predominant surface structures on the gold surface but also topographic features, like Au ad islands and Au vacancy islands, and also the chemical nature of adsorbed species from XPS S 2p spectra. In contrast to the S heads of small aromatic thiols, which exhibit a low affinity for Au ad , strongly reactive sulfide species react with the metal adatoms leading to well-ordered complexes.

New aspects of the surface chemistry of sulfur on Au(111): Surface structures formed by gold-sulfur complexes

“…These results, and those recently reported by our group [24], allow a deeper understanding of the sulfur-gold chemistry in 2D systems. Indeed, adsorbates include monomeric sulfur, monomeric sulfur-gold complexes, adsorbed disulfides and disulfide-gold complexes, and the substrate plays a significant role in the adsorbate geometry.…”

“…Similar quasi-rectangular polysulfide structures have been observed on the Au(001) surface, and the basic building blocks have been also assigned to S 2 species [23]. However, there are new evidences indicating that the disulfide species are stabilized by gold atoms forming well ordered disulfide-gold complexes [24].…”

Sulfur-driven switching of the Ullmann coupling on Au(111)

“…Secondly, on the terraces the herringbone reconstruction is completely lifted after the H2S exposure [33][34][35] . We attribute the protrusions to Au adatoms originating from the lifting of the herringbone, which are decorated with S to form S-Au complex 30,[36][37][38][39][40] . The STM images were acquired at 100 K. Even at this temperature, some of the S-Au are slightly mobile (circles in Fig.…”

Self-Assembled Decanethiolate Monolayers on Au(001): Expanding the Family of Known Phases

“…55 While for the Au(001) surface S can still deploy Au adatoms in sulfur−metal complexes, it seems that this is not always true for thiol molecules. 58,59 In fact, it was shown that the bridging thiolate motif (−RS−) is more preferred than the staple motif for the Au(001) surface. 3 When the hex reconstruction is lifted, generally monolayerhigh Au islands form, covered by a continuous molecular phase.…”