Copper Electrodeposition on Alkanethiolate Covered Gold Electrodes* (original) (raw)
Related papers
Journal of Electroanalytical Chemistry, 1995
Voltammetric data for the reductive desorption of alkanethiolate monolayers from gold electrodes reveal the presence of different adsorbate binding sites. This conclusion is based on a series of characterizations of monolayers formed from butanethiol and octanethiol at annealed mica-supported gold (Au/mica) and at gold supported by both chromium-primed silicon (Au/Si) and glass (Au/glass). At Au/mica, a single wave is observed for the desorption induced by a linear voltage scan. The voltammetry at Au/Si and Au/glass is, however, comparatively more complex, as reflected by the presence of at least one additional desorption wave. Results from structural characterizations (IR and X-ray photoelectron spectroscopies and electrochemical capacitance measurements) of the monolayers formed at each type of substrate and from morphological assessments (X-ray diffraction, underpotential metal deposition, and scanning tunneling microscopy) of the underlying substrates reveal that the differences in the voltammetry originate from differences in the microscopic roughnesses of the two types of substrates. Importantly, the morphological data indicate that the bulk of the gold films on all three supports has a pronounced (111) crystallinity, that the surface at Au/Mica is strongly (111) terraced, but that the surfaces at Au/Si and Au/glass have a much higher density of steps. The voltammetry at Au/mica, therefore, represents desorption from sites at Au(111) terraces. On the contrary, the voltammetry at Au/glass or Au/Si reflects desorption from both terrace and step sites with the adsorbates at step sites bound by as much as 25 kJ mol−1 more strongly than at terrace sites. The implications of our findings for descriptions of the nucleation and growth of these systems are discussed.
Surface structure and interface dynamics of alkanethiol self-assembled monolayers on Au(111)
The journal of physical chemistry. B, 2006
Scanning tunneling microscopy (STM) and high-resolution electron energy loss spectroscopy (HREELS) were used to examine the structural transitions and interface dynamics of octanethiol (OT) self-assembled monolayers (SAMs) caused by long-term storage or annealing at an elevated temperature. We found that the structural transitions of OT SAMs from the c(4 x 2) superlattice to the (6 x square root 3) superlattice resulting from long-term storage were caused by both the dynamic movement of the adsorbed sulfur atoms on several adsorption sites of the Au(111) surface and the change of molecular orientation in the ordered layer. Moreover, it was found that the chemical structure of the sulfur headgroups does not change from monomer to dimer by the temporal change of SAMs at room temperature. Contrary to the results of the long-term-stored SAMs, it was found that the annealing process did not modify either the interfacial or chemical structures of the sulfur headgroups or the two-dimension...