Underpotential deposition of silver polycrystalline platinum electrodes: Controlling phenomena derived from potentiostatic transients

Abstract

The electrodeposition of silver on polycrystalline platinum in 0.1 M HClO 4 at 30° C was studied using potentiostatic and potentiodynamic techniques. The electrodeposition of silver on platinum occurs within three well-defined regions (I, II and III). Region I (in the 0.9-0.8 V range) involves the formation of a upd silver monolayer. Region II is observed within a small potential window located on the positive potential side of the Ag/Ag + reversible electrode potential. It can be related to the two-dimensional (2-D) growth of the upd silver layer. Region III corresponds to the bulk deposition of silver. Potentiostatic current transients run in region II can be explained through simultaneous adsorption-desorption and nucleation and growth processes. The contribution of the latter increases as the applied potential approaches the Ag/Ag + reversible potential. The stripping of bulk silver differs from the stripping of silver electrodeposited in region II. The charge density of the latter derived from the current transients depends on both the electroformation time and potential, and can be represented through a 2-D nucleation and growth model applied to the stripping process.