In situ electrochemical, electrochemical quartz crystal microbalance, scanning tunneling microscopy, and surface X-ray scattering studies on Ag/AgCl reaction at the underpotentially deposited Ag bilayer on the Au(111) electrode surface

Uosaki, Kohei*; Morita, Jun*; Katsuzaki, Tomoko*; Takakusagi, Satoru*; Tamura, Kazuhisa   ; Takahashi, Masamitsu; Mizuki, Junichiro; Kondo, Toshihiro*

Ag/AgCl reaction at the Ag bilayer, which was underpotentially prepared on a Au(111) surface, was investigated using electrochemical quartz crystal microbalance (EQCM), scanning tunneling microscopy (STM), surface X-ray scattering (SXS), and electrochemical techniques. When the potential was scanned positively from -200 mV, the Cl ion was adsorbed on the Au(111) electrode surface around 0 mV, and then the phase transition of the adsorbed Cl ion layer from random orientation to ( ) structure took place at around +130 mV. The Ag bilayer and Cl ions were oxidatively reacted to form the AgCl monolayer with ( ) 13.9 structure around +200 mV, accompanied with the formation of AgCl monocrystalline clusters on the AgCl monolayer surface. The structure of the AgCl monolayer on the Au(111) surface was changed from ( )R13.9 structure to (44) structure around +500 mV.