A description of columnar structured platinum electrodes as an array of nm-sized thin cell electrodes

MARTINS, MAR¨ªA; RODRIGUEZ NIETO, FELIPE; SALVAREZZA, ROBERTO; ARVIA, ALEJANDRO; MARIA ELISA MARTINS

JOURNAL OF ELECTROANALYTICAL CHEMISTRY

ELSEVIER

Año: 1999 vol. 477 p. 14 - 24

0022-0728

Silver voltammetric anodic stripping from stabilized rough platinum electrodes in 1 M H2SO4+co Ag2SO4 (5x10-4 M¡Üco¡Ü10-3 M) and 1 M H2SO4 aqueous solutions, at 298 K, was investigated. The topography of these electrodes was determined by scanning tunneling microscopy (STM). The roughness factor, R, was varied from 10 to 71. The analysis of STM images showed that the rough structure consists of an array of nm-sized protrusions and voids as a columnar structured surface. For each value of R, the average size and volume of voids were determined. The voltammetric features of silver anodic stripping depend on R and the electrodeposited silver charge, QAg. The value of QAg(vs), the saturation value of QAg for voids, was estimated. The anodic stripping of underpotential deposited silver occurs in the potential range where oxygen electroadsorption on platinum takes place. By using data derived from STM imaging and equations that have been derived for the voltammetric anodic stripping reactions, in which the reactant is confined to nm-sized voids, the voltammetric behaviour of the system can be reproduced reasonably. Keywords : Rough platinum electrodes; Silver anodic stripping; Electrode topography influence; Reactions at nm-sized voids