Theoretical aspects of 2D electrochemical phase formation
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ORIGINAL PAPER
Theoretical aspects of 2D electrochemical phase formation Vladimir A. Isaev 1
&
Olga V. Grishenkova 1
&
Yury P. Zaikov 1,2
Received: 27 August 2020 / Revised: 5 October 2020 / Accepted: 14 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Two-dimensional electrochemical phase formation as a result of nucleation, growth, and overlap of disk-shaped nuclei of a new phase on the electrode surface is analyzed. This problem is considered based on the Kolmogorov-Johnson-Mehl-Avrami (KJMA) theory. General formulae applicable for any type of two-dimensional crystallization are derived. The theory of the double-pulse potentiostatic method is considered. Theoretical expressions are obtained for potentiostatic current density transients in the case of two-dimensional electrocrystallization at different durations and magnitudes of the first and second pulses (nucleation and growth pulses, respectively). The maxima of the current density transients are analyzed to obtain information about the mechanisms and parameters of nucleation and growth. The morphology of a continuous deposit layer is discussed in terms of Voronoi cells. Keywords Electrodeposition . Nucleation . Growth . 2D deposit layer
Introduction The processes of nucleation and growth largely determine the kinetics of electrodeposition, and therefore, they are the subject of numerous studies, e.g. [1–6]. The two-dimensional (2D) case will be considered in this paper. Nowadays, 2D phase transitions on surfaces or in adlayers attract special attention because they are associated with some important aspects of nanotechnologies, surface, interfacial, and material sciences, for example, ordered adsorption, surface reconstruction, nucleation, and growth phenomena [7–12]. 2D nucleation and growth processes play a significant role in cases of electrocrystallization on quasi-perfect (screw dislocation-free) own substrate, underpotential deposition of metals on foreign substrates, and the formation of thin films [7, 9, 13–18]. Electrodeposition under potentiostatic conditions is a convenient way to study the mechanism and kinetics of the 2D phase formation since the process can be directly controlled through the applied electrode potential and the interpretation of the current density transients is quite simple.
* Vladimir A. Isaev [email protected]; [email protected] 1
Institute of High Temperature Electrochemistry, Ural Branch of the Russian Academy of Sciences, Ekaterinburg 620137, Russia
2
Ural Federal University, Ekaterinburg 620002, Russia
Fleischmann and Thirsk [15–17] investigated the kinetics of the successive formation of several calomel monolayers upon a mercury electrode and were the first to derive expressions describing the dependences of current density on time for instantaneous and progressive nucleation with growth controlled by the incorporation of new material into the lattice at the edge of the growing circular nuclei (for a monolayer). In the FT model, the overlap of 2D nuclei was considered bas
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