Disk electrodes Koutecky-Levich equation

Figure 9 Use of the Koutecky-Levich equation to correct for diffusive transport effects on the anodic dissolution of Cu in 1 mol dm-3 NaCl recorded on a rotating disk electrode.

Typical examples discussed below can help us gain a better understanding of the application of RDEs. Jiang et al. [44] studied the ORR at a rotating disk electrode with multiple small potential steps. Figure 21.6 shows a serial of current-potential curves for the ORR at a HT-FeTPP/CoTPP/PG rotating disk electrode in an 02-saturated 0.5 M sulfuric acid electrolyte. With increasing rotation rate, the catalytic current increases. The kinetic analysis of the ORR at the catalyst coated RDE can be carried out by the Koutecky-Levich equation ... 

Kanzaki, Y., Tokuda, K., and Bruckenstein, S. (2014) Dissociation rates of weak acids using sinusoidal hydrodynamic modulated rotating disk electrode employing Koutecky-Levich equation. /. Electrochem. Soc., 161 (12), H770-H779. 

The mass transfer correction for a rotating disk electrode was obtained by rearranging the Koutecky-Levich equation (Eq. (9.46)), and is shown in the following equation ... 

Koutecky-Levich plot — The diffusion-limited current fiim> diff at a -> rotating disk electrode is given by the -> Levich equation based totally on mass-transfer-limited conditions. The disk current in the absence of diffusion control, i.e., in case of electron transfer control, would be... 

Schmidt et al. used RDE to study the impact of the Nafion film thiekness on the mass transport resistance for HOR (Figure 11.10) [48]). They first deposited a thin layer of Pt/C on the surface of a glassy carbon disk, and covered the Pt/C layer with a thin layer of Nafion. The purpose of the thin Nafion film was to improve the adhesion of the catalyst on the electrode surface. An additional mass transport resistance was encountered due to the presence of this thin Nafion film, and Equation 11.21 applies. Figures 11.10(a) and 11.10(b) show the limiting HOR current densities with 15 and 0.1 pm-thiek Nafion films, respectively. Figure 11.10(c) shows the Koutecky-Levich plot for Nafion films of 0.1, 2.4, 3.6, and 15 pm thickness. Figure 11.10(d) shows the inverse of the Levieh intercept (ca )... 

Sheng et al. [34] recently compared the rotating disk electrode (RDE) studies of the HOR in acid and alkaline and those for the carbon-supported Pt (Pt/C) for the first time. RDE studies are used to separate the current into its kinetic- and diffusion-based constituents, as shown by the Levich-Koutecky equation ... 

The rotating disk electrode measurements for the nanoparticle-deposited diamond film under identical experiments conditions revealed that there was no well-defined limiting current for oxygen reduction, which merges with hydrogen evolution at -0.46 V. From the Koutecky-Levich (K-L) equation, the number of electrons n involved in the reduction was calculated to between 2... 

The Nation coating must protect the underlying sensor elements from compounds in the body, selectively transport O2 relative to glucose, and should preferably inhibit interfering species such as ascorbic acid (2,7J-7J). The permeability of Nation to several compounds was determined using a Nafion-coated rotating disk electrode (79). From plots of the inverse of the observed disk current as a fiuiction of the inverse of the square root of the rotation rate (a Koutecky-Levich plot) the permeability. Pm, was obtained. This value was determined for a series of Nation thicknesses, measured by ellipsometry, and the effective diffusion coefficients were obtained, according to equation 1. 

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