AVS 63rd International Symposium & Exhibition
    Fundamental Discoveries in Heterogeneous Catalysis Focus Topic Wednesday Sessions
       Session HC+NS+SS-WeA

Invited Paper HC+NS+SS-WeA7
Sulfur-Metal Complexes on Surfaces of Copper, Silver, and Gold

Wednesday, November 9, 2016, 4:20 pm, Room 103A

Session: Nanoscale Surface Structures in Heterogeneously Catalyzed Reactions
Presenter: Patricia A. Thiel, Iowa State University
Authors: P.A. Thiel, Iowa State University
H. Walen, RIKEN Surface and Interface Science Laboratory, Wako, Saitama, Japan
D.-J. Liu, Ames Laboratory, Ames, IA
J. Oh, RIKEN Surface and Interface Science Laboratory, Wako, Saitama, Japan
H.J. Yang, University College London, UK
Y. Kim, RIKEN Surface and Interface Science Laboratory, Wako, Saitama, Japan
Correspondent: Click to Email
The nature of sulfur interaction with surfaces of coinage metals (M=Cu, Ag, Au) is relevant to aspects of heterogeneous catalysis, corrosion, and self-assembled monolayers. We have discovered a number of unexpected complexes—independent, molecule-like MxSy species—that form on low-index M surfaces. In a sense, these complexes are iidway between the well-known phenomena of chemisorption and adsorbate-induced reconstruction. Our primary experimental tool is scanning tunneling microscopy (STM) used in ultrahigh vacuum. We tailor our experimental conditions to isolate the complexes, by working at ultra-low sulfur coverage to avoid competition from surface reconstructions. Furthermore, we prepare the surface at 300 K, but image at 5 K, in order to immobilize these small species. Density fucntional theory (DFT) is used to interpret the experimental results. For instance, application of DFT is essential to identify the complexes that form on Cu(111), Ag(111), and Au(100), and this identification is made both on the basis of their physical characteristics in real vs. stiimulated STM images (size, orientation, shape) as well as their calculated stability. On other surfaces, including Au(111), Cu(10o0), and Au(110), MxSy complexes do not form under comparable conditions. This broad database and extensive analysis provides insights into factors that favor complexation in this class of systems.