In situ structural study on underpotential deposition of Ag on Au(111) electrode using surface X-ray scattering technique

Abstract

In situ surface X-ray scattering (SXS) measurements were carried out to study the structure of a Ag layer on a Au(111) electrode formed by underpotential deposition (UPD) in sulfuric acid solution. Specular rod profiles showed that a monolayer of Ag was formed at a potential between the second and third UPD peaks, and a bilayer of Ag was formed at a potential between the third UPD peak and bulk deposition. Non-specular rod profiles demonstrated that electrochemically deposited Ag atoms both in the first and second layers were situated at the three-fold hollow cubic closest packing (ccp) site of the underlying Au and Ag layers, respectively.

Stability of underpotentially deposited Ag layers on a Au(111) surface studied by surface X-ray scattering

“…It was then transferred to an electrochemical cell with the surface being covered with a drop of ultrapure water to avoid any surface contamination. Upd Ag layers on the Au(111) electrode surface were prepared in a 50 mM H 2 SO 4 solution containing 1 mM Ag 2 SO 4 as previously reported [29] by scanning the potential from 650 mV (Ag/Ag + ) to 50 mV and 10 mV, where Ag upd pseudomorphic mono-and bi-layers, respectively, are known to be formed on a Au(111)-(11) surface [29]. The electrode was then washed with ultrapure water, dried by blowing ultrapure N 2 gas, and then transferred to an SXS cell through ambient atmosphere.…”

“…Underpotential deposition (upd) is one of the best techniques to prepare ultrathin metal films on single crystal electrode surfaces with well-defined atomic arrangements [1][2][3]. The potential dependent structures of upd metal films with atomic resolution have been studied in situ by scanning tunneling microscopy (STM) [1,[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], atomic force microscopy (AFM) [22,23], and surface X-ray scattering (SXS) [24][25][26][27][28][29][30][31][32].…”

“…Upd of Ag is one of the most studied systems and the structure of Ag upd layers prepared on Au(111) has been extensively studied with an atomic resolution [4][5][6]10,12,19,20,29]. We also have studied the structure of Ag upd layers on Au(111) using in situ SXS and found that pseudomorphic Ag monolayer and bilayer are formed on Au(111) surface at 50 mV (vs. Ag/Ag + ) and 10 mV, respectively [29]. Here we studied the structures of the Ag upd mono-and bi-layers on Au(111) surface as-prepared and those after the circuit was disconnected and the surface was exposed to ambient atmosphere with an atomic dimension by SXS.…”

Electrodeposition of Ag and Pd on a reconstructed Au(1 1 1) electrode surface studied by in situ scanning tunneling microscopy

“…Electrochemical deposition of Ag on Au(111) electrode surface is a good model system to study the morphology of the deposited layer because the interaction and the lattice misfit between a metal deposit and a substrate is very strong and negligibly small (0.4 %), respectively [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] and has been studied by a wide variety of techniques, including scanning tunneling microscopy (STM) [1,2,5,8,9,14,16], atomic force microscopy (AFM) [3,4,6], second harmonic generation (SHG) spectroscopy [13], quartz crystal microbalance (QCM) [7], X-ray diffraction [11,12] and extended X-ray absorption fine structure (EXAFS) [10]. In particular underpotential deposition (UPD) of Ag has received special attention and the structures of adsorbates, both metal and anion, and their dependencies on the potential and electrolyte composition have been well studied [2][3][4][5][6].…”

“…In particular underpotential deposition (UPD) of Ag has received special attention and the structures of adsorbates, both metal and anion, and their dependencies on the potential and electrolyte composition have been well studied [2][3][4][5][6]. It has been reported that UPD Ag layer of various coverage up to two monolayer is formed depending on the electrode potential [14,15]. Reports on the overpotential deposition (OPD) of Ag on a Au(111) surface are, however, very limited [9,14].…”