Potential-Controlled Step Flow to 3D Step Decoration Transition: Ni Electrodeposition on Ag(111)

A novel growth effect, the potential-controlled transition from 2D step-flow growth (-0.690ex0exVAg/AgCl) to (i) selective growth of 3D admetal islands at substrate steps (-0.730ex0exV) and (ii) 3D island growth on steps and substrate terraces (-0.850ex0exV), is demonstrated for Ni electrodeposition on Ag(111). The nucleation and growth process apparently proceeds via direct deposition from the solution at step sites and can be rationalized by a kinetically controlled multilayer growth process, where the higher layer nucleation rate increases more with overpotential than does the 2D growth rate.