In situ Structural Studies of the Underpotential Deposition of Copper onto anIodine Covered Platinum Surface Using X-ray Standing Waves

摘要

We present initial results of an in situ structural investigation of theunderpotential deposition of copper on an iodine platinum/carbon layered synthetic microstructure, using x ray standing waves generated by specular (total external) reflection and Bragg diffraction. We also compare the result of surface coverage isotherms derived from both electrochemical and x-ray measurements. The underpotential deposition (UPD) process 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. In this process, submonolayer to monolayer(s) amounts of a metal can be electrodeposited on a foreign metal substrate in a quantifiable and reproducible fashion prior to bulk deposition. Numerous electrochemical and spectroscopic techniques have been utilized to probe the mechanism(s) of formation, and the structural properties of UPD layers. Conventional electrochemical methods have been used to obtain thermodynamic and kinetic information about the UPD process. Cyclic voltammetry and current transient2 experiments are the methods of choice in these types of studies. Structural features of the UPD layer were first derived, indirectly, from equilibrium-coverage potential isotherms using single crystal substrates.