Basic aspects regarding irregular metal surfaces and their application in electrochemistry

The topography and other properties related to disordered metal surfaces play an important role in deposition, corrosion and growth phenomena. Metal surfaces resulting from columnar or dendritic metal deposits can be taken as models of anisotropic and isotropic strong surface disorder, respectively. The topography of rough columnar surfaces can be determined by scanning tunneling microscopy at different scales and described by means of the dynamic scaling theory. Roughness relaxation kinetics can be followed by electrochemical techniques and interpreted through a coalescence-type mechanism. Typical examples of electrochemical reactions at this type of electrodes are presented. The study of the electrochemical formation of 3D or 2D metal dendrites provides basic information about the development of either diffusion limiting aggregation-type or dense radial patterns and the design and working condition ranges. In this case, the influence of convection and, particularly, that of the relative contribution of migration and diffusion on determining the topography of the object has been established. A generalized model based upon a Monte Carlo simulation has accounted for the experimental results.La topographie et les autres propriétés liées aux surfaces métalliques désordonnées jouent un rôle important dans la déposition, la corrosion et les phénomènes de croissance. Les surfaces métalliques provenant de dépôts métalliques dont les formes sont des colonnes ou dendrites peuvent être considérées comme des modèles d'un fort désordre superficiel, anisotropique et isotropique, respectivement. La topographie des surfaces avec des colonnes peut être déterminée par STM à des échelles différentes et décrite par la théorie de "dynamic scaling". La cinétique de relaxation de la rugosité peut être suivie par des techniques électrochimiques et interprétée par un mécanisme de coalescence. On présente des exemples caractéristiques de réactions électrochimiques à ce genre d'électrodes. L'étude de la formation électrochimique de dendrites métalliques de types 3D ou 2D donne des informations de base sur le développement soit d'agrégats limités par la diffusion, soit de structures radiales compactes, de même que des informations sur la forme et les conditions de travail. Dans ce cas, l'influence de la convection a été déterminée, et notamment, l'influence de la contribution relative de la migration et de la diffusion sur la topographie superficielle. Un modèle généralisé basé sur une simulation de type Monte Carlo a permis de rendre compte des résultats expérimentaux

An interdisciplinary approach to the electrochemistry at solid electrodes

An interdisciplinary approach to the electrochemistry at solid electrodes is presented here taking into account new basic interpretations for either phase growth or phase disruption under conditions far from equilibrium. For this purpose imaging data derived from scanning tunneling microscopy (STM) and atomic force microscopy (AFM) at different scale lengths are extremely useful. This approach provides new insights into roughness development, roughness decay and reactivity at solid electrodes. The study of mobile interfaces by the sequential application of in situ STM data and an interpretation based on the dynamic scaling theory furnish a qualitative and a quantitative description of surface irregularities, and provide information about the interface evolution mechanism under steady and non-steady roughness regimes. Various examples of electrochemical interest are discussed on the basis of this interdisciplinary approach

Interface dynamics for copper electrodeposition: The role of organic additives in the growth mode

An atomistic model for Cu electrodeposition under nonequilibrium conditions is presented. Cu electrodeposition takes place with a height-dependent deposition rate that accounts for fluctuations in the local [formula presented] ions concentration at the interface, followed by surface diffusion. This model leads to an unstable interface with the development of protrusions and grooves. Subsequently the model is extended to account for the presence of organic additives, which compete with [formula presented] for adsorption at protrusions, leading to a stable interface with scaling exponents consistent with those of the Edwards-Wilkinson equation. The model reproduces the interface evolution experimentally observed for Cu electrodeposition in the absence and in the presence of organic additives. © 2002 The American Physical Society.Fil:Solari, H.G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina