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Atomistic theory of electrochemical

Electrocrystallization was certainly among Kaischev s favorite subjects, and I suppose that this is the reason why he directed to this scientific field his first Bulgarian co-workers and later also eminent scientists E. Budevski, J. Malinovski, A. Scheludko, G. Bliznakov, and B. Mutaftchiev. They all started their most successful scientific careers, namely, in the field of electrochemical science [31-33], In 1974, R. Kaischev participated also in the development of the atomistic theory of electrochemical phase formation [34, 35], which accounts for the specific properties of small clusters of atoms and molecules (see also [10,12]). [Pg.412]

In Chapter 1.3.3 we have already defined the frequencies of direct attachment and detachment, W+i and W.i, of single atoms to and from the /th site of the crystal surface in the case of electrocrystaUization. In equation (2.9) the quantities co+ and fii represent the frequencies of direct attachment and detachment of single atoms to and from an n-atomic cluster and were defined by Milchev, Stoyanov and Kaischew in the framework of the atomistic theory of electrochemical nucleation [2.10-2.12], Here we shall clarify the meaning of this definition as follows. [Pg.86]

The readers who are already acquainted with Chapter 2.1.2 should have a fairly good idea of the physical significance of equation (2.80). However, in the early seventies the exact meaning of this expression was still obscure. Though, one thing was clear an atomistic expression for the stationaiy nucleation rate could be obtained in any particular case of phase formation if the frequencies 6>+ and o). were presented as functions of the supersaturation A/i. The first result ofthis finding was the atomistic theory of electrochemical nucleation developed by Milchev, Stoyanov and Kaischew in 1974 [2.10-2.12] (see also [2.5, 2.62-2.65]). The next Section presents the basic theoretical results obtained by these authors. [Pg.112]

Figure 2.7 Data for the stationary nucleation rate of silver on platinum from Figure 2.4 plotted in the coordinates of the atomistic theory of electrochemical nucleation [2.63].(With... Figure 2.7 Data for the stationary nucleation rate of silver on platinum from Figure 2.4 plotted in the coordinates of the atomistic theory of electrochemical nucleation [2.63].(With...
Under the specific conditions of electrochemical metal deposition, the critically sized clusters of the new phase have been found to consist of only a few atoms, where classical thermodynamic bulk quantities cannot be applied. Therefore, the original kinetic theory of Becker and Doering was further developed to an atomistic theory of nucleation. [Pg.200]

The striking quantitative contradiction between the classical nucleation theory and the experimental data accompanies the studies of electrochemical nucleation since the time of Thomfor and Volmer [2.29] who were the first to obtain a surprisingly low value for the size of a critical mercury nucleus on a platinum substrate. The problem has been successfully solved by the atomistic theory of the nucleation rate [2.10-2.12, 2.33, 2.62-2.66], which answers the question how to interpret the experimental data on electrochemical nucleation The next Section contains a survey of these theoretical considerations. [Pg.106]

In the last section, we discussed the use of QC calculations to elucidate reaction mechanisms. First-principle atomistic calculations offer valuable information on how reactions happen by providing detailed PES for various reaction pathways. Potential energy surfaces can also be obtained as a function of electrode potential (for example see Refs. [16, 18, 33, 38]). However, these calculations do not provide information on the complex reaction kinetics that occur on timescales and lengthscales of electrochemical experiments. Mesoscale lattice models can be used to address this issue. For example, in Refs. [25, 51, 52] kinetic Monte Carlo (KMC) simulations were used to simulate voltammetry transients in the timescale of seconds to model Pt(l 11) and Pt(lOO) surfaces containing up to 256x256 atoms. These models can be developed based on insights obtained from first-principle QC calculations and experiments. Theory and/or experiments can be used to parameterize these models. For example, rate theories [22, 24, 53, 54] can be applied on detailed potential energy surfaces from accurate QC calculations to calculate electrochemical rate constants. On the other hand, approximate rate constants for some reactions can be obtained from experiments (for example see Refs. [25, 26]). This chapter describes the later approach. [Pg.538]


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