Formation of two-dimensional (2D) lead dendrites by application of different regimes of electrolysis

Electrodeposition of lead from nitrate electrolyte in constant regimes of electrolysis was analyzed and the obtained powder lead deposits were examined by scanning electron microscopy. Polarization curve for lead electrodeposition consisted of two parts separated by an inflection point. The first part of the polarization curve was characterized by a linear dependence of the current density on overpotential. The linear part of the polarization curve corresponded to ohmic-controlled electrodeposition and single lead crystals were formed in this range of overpotentials. A rapid increase in the current density with increasing overpotential was observed after the inflection point (the second part of the polarization curve). Two-dimensional dendrites were the dominant morphological forms obtained at overpotentials and current densities belonging to the second part of the polarization curve, indicating that the rapid increase of the current density with increasing overpotential corresponded to activation controlled electrodeposition at the tips of the formed dendrites. Comparing the morphologies of the obtained lead deposits with those belonging to the same group of metals (metals characterized by a high exchange current density), such as silver, cadmium, and tin, a strong dependence between the nucleation type and the shape of dendrites for the metals belonging to the same group was established.