Rotating disk electrode properties

Figure 8.12 Relationships between the catalytic properties and electronic structure of Pt3M alloys correlation between the specific activity for the oxygen reduction reaction measured experimentally by a rotating disk electrode on Pt3M surfaces in 0.1 M HCIO4 at 333 K and 1600 lev/min versus the li-band center position for (a) Pt-skin and (b) Pt-skeleton surfaces. (Reprinted with permission from Stamenkovic et al. [2007b]. Copyright 2007. Nature Pubhshing Group.)...

Effective ionic diffusivities at a rotating-disk electrode are calculated from the Levich equation as derived for constant physical properties, used here in inverted form ... 

To further evaluate the electrocatal)4ic properties, rotating disk electrode (RDF) experiments were performed to characterize the number of electrons transferred in the... 

The electron affinity of 3-(iV-methylpiperazino)-5-nitroindazole, 3,5-dinitroindazole, and molecular complex of the last with water is discussed on the basis of their half-wave potentials and in connection with their eventual radiosensitizing properties [667], The mechanism of EC behavior of 2-substituted 5(6)-nitrobenzimidazoles in acetonitrile has been investigated by classical polarography, cyclic voltammetry, and platinum rotating disk electrode with a ring (RDER) [888,991], It is shown that... 

The current densities in KIO3 are lower than in K3pe(CN)6 solutions. The pH of minimum potential is also shifted to somewhat higher pH in KIO3 solution. The difference in their behavior may be attributed to ionic radii of IO3 and Fe(CN)6 ions. IO3 ions have much larger size and are thus may provide a hindrance to the anodic dissolution reactions. The value of 5ln(Iss)/8pH is about 1.45. This is lower than the value of 2.303 obtained by Macdonald et al. This study was carried out in static environment, unlike the rotating disk electrode set-up used by MacDonald et al. The differences in the value of this slope may probably be attributed to the differences in mass transfer properties in solution. 

Determine the catalytic properties of the new catalyst for hydrogen (H2) and H2 + CO oxidation and improve the thin layer rotating disk electrode method. 

Figure 8.4 shows the importance of the coordination mode around the metal ion for the electrochemical properties of the layer. In Fig. 8.4 the mediation of the Fe(II)/(III) oxidation is studied by using a rotating disk electrode. Initially a thin film of [Ru(bipy)2(PVP)5Cl] is used and with this coating the current potential curve I is obtained (see Fig. 8.4b). On photolysis of the coating and formation of the aquocomplex (according to Reaction 5) curve II is obtained. Rotating disk behavior very clearly shows that the redox potential of the modifying layer is of prime importance to the electrochemical properties of the modified electrode.

For electroanalysis, the working electrode can be a hanging wire of millimeter dimensions (a millielectrode), a flat disk of similar dimensions, or a disk of micron dimensions (microelectrode) which may also be rotated in the horizontal plane to give the "rotating disk electrode". All these systems have different transport properties. The use of microelectrodes has made a particular impact on electroanalytical applications. ... 

The redox properties of the sandwich complexes have been studied by cyclic-, rotating disk electrode voltammetry and electrolysis, in different solvents (CH202,DMF,DMSO,benzonitrile). The reference for the potentiel scale is the ferri/ferrocenium couple. 

The electrochemical properties of all of these bis-adducts have been studied in reasonable detail, using either cyclic voltammetry (CV) or steady-state voltammetry (SSV) at a rotating disk electrode [10]. While many interesting observations have been made about their electrochemical behavior, the most relevant to the present work concerns the cis-2 isomer, 3 [11]. The bis(methano)fullerenes with a cis-2 addition pattern exhibit a chemically irreversible second one-electron reduction, as determined by using CV and SSV on a rotating disk electrode. Of all the isomers studied, the cis-2 is the only one that exhibits such an irreversible second reduction step on the voltammetric time scales. This observation led to the initiation of a project that eventually culminated in the observations that are presented in this chapter. Most of the work reported here was... 

This approximate relationship is similar to those for centrifugal atomization of normal liquids in both Direct Droplet and Ligament regimes. However, it is uncertain how accurately the model for K developed for normal liquid atomization could be applied to the estimation of droplet sizes of liquid metals Tombergl486 derived a semi-empirical correlation for rotating disk atomization or REP of liquid metals with the proportionality between the mean droplet size, rotational speed, and electrode or disk diameter similar to the above equation. Tornberg also presented the values of the constants in the correlation for some given operation conditions and material properties. 

It is our belief that a full and detailed understanding of the electron-transfer properties of organometallic complexes can be achieved only by a combination of chemical and electrochemical studies the use of one alone can lead to erroneous conclusions. Because we have insufficient space to provide a discussion of the theory and practice of elementary electrochemical techniques we refer the reader to several excellent treatments which also include an explanation of commonly used terminology (25-30). The synthetic chemist should not be deterred from routinely using techniques such as cyclic voltametry (CV),1 voltametry at rotating metal disk electrodes, or controlled potential electrolysis (CPE), coulometry, and chronoamperometry. The proper employment of such techniques, for which instrumentation is readily available, should prove sufficient for all but the most detailed studies. 

---