Modeling of single phase electrocrystallization processes: Growth of paraboloids with concurrent evolution of hydrogen

A generalized form of the current time transient (CTT) has been derived for the charge transfer controlled model of growth of paraboloids. The transient current is shown to pass through a single maximum before approaching a steady-state value. The maximum is estimated to be coincidental with 77% of the substrate coverage in the case of "instantaneous" nucleation and with 90% coverage for the "progressive" nucleation and growth of paraboloids. The dependence of the surface area of the paraboloidal growth forms on time is formulated and, consequently, the kinetics of the concurrent evolution of hydrogen has been incorporated in the formulation of the CTTs. A particular CTT equation is thereby derived for the growth of paraboloids that are "instantaneously" formed on a monolayer of deposit. It is shown that the exact shape of some of the CTTs recorded during the electrocrystallization of cobalt can be reproduced by the derived CTT.