Current transient and in situ AFM studies of initial growth stages of electrochemically deposited nickel cobalt hydroxide nanosheet films.

Current transient evolution and in situ electrochemical AFM were used to study the initial stages of growth of electrochemically deposited nickel cobalt hydroxide films for energy storage applications. Current transients were taken at constant potentials, from -700 mV to -1000 mV, with a step of 50 mV. The current transients were fitted with three different nucleation models: Scharifker-Hill, Scharifker-Mostany and Mirkin-Nilov-Heerman-Tarallo and the results revealed that film growth was governed by a 3D instantaneous nucleation mechanism. In situ electrochemical AFM studies confirmed the instantaneous nucleation mechanism and revealed the early stage formation of nanosheets. The in situ AFM results were supported by the ex situ FEG-SEM results, showing the formation of nanoneedles at the first stages of nucleation and the growth into nanosheets with the increasing deposition time.