Concentration Dependence of the Underpotential Deposition of Silver on Pt(111):Electrochemical and UHV Studies

摘要

We report on a study of the underpotential deposition of silver on well-definedPt(111) electrodes with emphasis on its concentration dependence. Electrochemical as well as ultrahigh vacuum surface techniques have been employed. The voltammetry for deposition of silver on Pt(111) depends on the silver ion concentration but it does not follow the Nernstian behavior of 6omV shift per decade change in concentration. We also find that when the silver ion concentration is 1.00mM the electrodeposition is via adsorption in a well-defined manner, whereas at a concentration of 0.005 mM the mechanism involves three-dimensional nucleation and island formation. In addition, two monolayers of silver are deposited at underpotentials but the stability of the second layer is a strong function of the silver ion concentration in solution. When the silver ion concentration is 1.00mM, rinsing the electrode at controlled potential (with supporting electrolyte containing no silver in solution) results in essentially complete removal of the second layer of silver. However, when the deposition is from a solution containing silver at a concentration of 0.10mM, the layer is stable to the same rinsing procedure.... Silver, Underpotential deposition, Pt(111).