Figure 1.

Experiment (solid) and simulated voltammetry for Ni deposition in electrolyte containing the indicated PEI concentrations; the Levich inverse square root dependence of the boundary layer thickness on the rotation rate of the rotating disk electrode is assumed. Details regarding the voltammetry, experiment and simulations are contained in earlier work.²³ Simulations are shown both for the parameters found in Table I of this work, corresponding to 20% deposition efficiency on the passivated surface (dot), and the 10% de deposition efficiency used previously²³ (dash). Some simulations superimpose because the shift of suppression breakdown due to a 2 × increase of adsorbate consumption arising from the increased deposition current efficiency is identical to that associated with a 4 × decrease of rotation rate (doubling the boundary layer thickness and thus halving the transport limit of the adsorbing suppressor flux).²³ Data and simulations are plotted against the applied potential, with cathodic currents positive.