Electrodeposition Real process

Generally, the process of nucleation in electrodeposition of metals can be considered as occuring on ideal or real substrates. Ideal substrates are considered free of ciystal imperfections and are characterized by an atomically smooth, homogeneous surface which does not exhibit preferred nucleation sites. On such substrates the number of nucleation sites, Zo, is equal to the number of adsorption sites Ns (cf. Section 8.3). 

Certain real systems seem to be described by OLA, notably electrodeposition on a sharp point (39) and dielectric breakdown (33,40). The second class involves cluster formation by the homogeneous aggregation of a collection of two clusters of comparable size (37, ) (cluster-cluster aggregation, CA) and the resultant aggregate has a more open structure and lower fractal dimension, D = 1.4 ( d = 2) and 1.8 (d = 3). Real smoke ( ) and colloids (41) seem to have D = 1.8 this is a satisfying verification of the model. A process that has not, however, been included in the simulations is rearrangement within the clusters. This would lead to denser structures with higher Hausdorff dimensions ( ). 

Comparing polarization curves (/tot) recorded onto GC and Co electrodes (Fig. 2.35) one can see that the electrodeposition process onto Co electrode commences at more positive potentials, while the current density of the second inflection point, as well as the current density at potentials more negative than that point, is smaller. Such behavior is reasonable to expect since the overvoltage for Co electrodeposition should be higher for GC than for Co electrodes, while at the same time the increase of the real surface area onto Co... 

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