In situ X-ray Standing Wave Study of Cu UPD on an Iodine Covered Platinum Surface

摘要

In situ structural investigations of the underpotential deposition of copper onan iodine covered platinum surface have been carried out using x ray standing waves generated by specular (total external) reflection and Bragg diffraction. Surface coverage isotherms derived from both electrochemical and x-ray measurements are also compared. The growth mode of the copper ad-layer appears to be strongly influenced by the electrode's surface morphology. The process of underpotential deposition (UPD) of metals has been extensively studied during the past two decades due to its theoretical and practical importance in fields such as electrocrystallization, catalysis, and surface chemistry. Numerous electrochemical and spectroscopic techniques have been utilized to probe the mechanism(s) of formation, and the structural properties of UPD layers. Conventional electrochemical techniques have been used to obtain thermodynamic and kinetic information about the UPD process. Although electrochemical methods are invaluable in controlling and measuring thermodynamic parameters such as applied potential, charge, and coverage, any structural inferences are always indirect and often model dependent.