Koutecky-Levich theory

In electrochemical measurements using rotating electrode technique and data treatment using Koutecky—Levich theory, the most commonly used solution viscosity is kinematic viscosity. Therefore, in the following sections, we will only focus on this kinematic viscosity. 

These two equations have the form predicted by the Koutecky—Levich theory, which will be discussed more in Chapters 5 and 6. 

As discussed in Figure 5.5, Koutecky—Levich theory can be used to analyze the current—potential curves, and the equations used for this analysis are Equations (5.23) and (5.24). To obtain the ORR exchange current density (i°), the electron-transfer... 

Although, in theory, the Koutecky-Levich equation can be applied to estimate n y and k at any part of the voltammogram (provided that the conditions stated above are satisfied), for practical reasons only limiting (plateau) currents can be acquired with adequate reproducibility to yield suitable Koutecky-Levich plots. 

Oct. 14, 1922, Kromeriz, then Czechoslovakia - Aug. 10, 2005, Berlin, Germany) Koutecky was a theoretical electrochemist, quantum chemist, solid state physicist (surfaces and chemisorption), and expert in the theory of clusters. He received his PhD in theoretical physics, was later a co-worker of -> Brdicka in Prague, and since 1967 professor of physical chemistry at Charles University, Prague. Since 1973 he was professor of physical chemistry at Freie Universitat, Berlin, Germany. Koutecky solved differential equations relevant to spherical -> diffusion, slow electrode reaction, - kinetic currents, -> catalytic currents, to currents controlled by nonlinear chemical reactions, and to combinations of these [i-v]. For a comprehensive review of his work on spherical diffusion and kinetic currents see [vi]. See also Koutecky-Levich plot. 

RDE is a commonly used technique for investigating the ORR in terms of both the electron transfer process on electrode surface and diffusion—convection kinetics near the electrode. To make appropriate usage in the ORR study, fundamental understanding of both the electron transfer process on electrode surface and diffusion—convection kinetics near the electrode is necessary. In this chapter, two kinds of RDE are presented, one is the smooth electrode surface, and the other is the catalyst layer-coated electrode. Based on the electrochemical reaction 0 + ne R), the RDE theory, particularly those of the diffusion—convection kinetics, and its coupling with the electron-transfer process are presented. The famous Koutecky—Levich equation and its... 

Figure 7.14 (A) Current—potential curves for Co"HFPC adsorbed on a rotating graphite disk electrode at different rates of rotation as (marked on each curve), recorded in an air-saturated 0.1 M Na2S04 solution buffered to a pH 6. Temperature 20 °C. Potential scan rate 10 mV s (B) Koutecky—Levich plot, data from (B). The thinner solid line is calculated according to Levich theory for a 2-electron O2 reduction process. The thicker solid line and data points are the experimental data. Reprinted with permission from Ref. 47.

Figure 2.5. Koutecky-Levich plot using data from Figure 2.4. The theoretical line is calculated according to Levich theory for a 4-elecfron O2 reduction process [11]. (Reproduced by permission of ECS—The Electrochemical Society, from Zhang L, Song C, Zhang J, Wang El, Wilkinson DP. Temperature and pFl dependent oxygen reduction catalyzed by iron fluoro-porphyrin adsorbed on a graphite electrode.)...

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