Rotating disk electrode measured with

Figure 8.17 Activities of Pt(l 1 l)-wML Pd electrodes from rotating disk electrode measurements, with corresponding ball models (a) electro-oxidation of formic acid in 0.1 M HCIO4 ...

This value is based on Cu2+ diffusivities calculated Arvia et al. (A5) from limiting-current measurements at a rotating-disk electrode by, with CuS04 concentrations below 0.1 M. In practical applications (e.g., copper refining or electrowinning) higher Cu2+ concentrations are often required, as is also the case in free-convection limiting-current measurements. 

Electrocatalysts with a 1/8 of monolayer Pt loading on Ru nanoparticles have been synthesized by spontaneous deposition of Pt on a Ru surface, each of which have at least three times larger mass-specific activity for H2 oxidation than two commercial catalysts and a larger CO tolerance, as determined by thin film rotating disk electrode measurements. 

C03M03N was, however, used as a precursor to C0M0N2 via reaction with NH3 at 400 °C. The actual formula reported was C006M02 4N2 with a small Co(M) component. Rotating disk electrode measurements in acidic media under H2 atmosphere demonstrated that currents for the HER reaction were achieved at overpotentials of around 0.2 V, which indicates promising catalytic activity in the C02M0N sample. 

In fact the ring-disk electrode is a combination of an ordinary rotating disk electrode (RDE) with a ring electrode. (The term ring electrode usually refers to the case where the region r-2 < r < rs is active with respect to the smface process r is the radius measured from the center of the cylindrical tip). This means that the regions 0 < r < a-2 and essential feature of this system is that there is an inactive region at the center of the disk.)... 

Fig. 44 NaCl increases the permeability of polyelectrolyte multilayers for the redox-active ferricyanide, as seen by rotating disk electrode measurements (reprinted with permission from [471], Cop)right 2011 American Chemical Society)...

Shigehara K, Oyama N, Anson FC (1981) Evaluation of rate constants for redox selfexchange reactions fi om electrochemical measurements with rotating-disk electrodes coated with polyelectrolydes. Inorg Chem 20 518-522... 

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... 

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.)...

Figure 14.12 CO bulk electro-oxidation at PtRu alloys, (a, b) PcRui j /Ru(0001) (x = 0.07, 0.25, 0.47) surface alloys measured in a flow cell with a CO-saturated electrolyte, (c) Freshly sputtered Pto.sRuo.s bulk alloy in a rotating disk electrode setup (data from Gasteiger et al. [1995]), compared with a Pto.53Ruo,47/Ru((X)01) surface alloy.

Electrode processes are often studied under steady-state conditions, for example at a rotating disk electrode or at a ultramicroelectrode. Polarog-raphy with dropping electrode where average currents during the droptime are often measured shows similar features as steady-state methods. The distribution of the concentrations of the oxidized and reduced forms at the surface of the electrode under steady-state conditions is shown in Fig. 5.12. For the current density we have (cf. Eq. (2.7.13))... 

Mass-transfer rates from limiting-current measurements in well-supported solutions should invariably be correlated with ionic and not with molecular diffusivities. The former can be calculated from limiting-current measurements, for example, at a rotating-disk electrode. 

Shuman and Michael [326,327] introduced a technique that has sufficient sensitivity for kinetic measurement at very dilute solutions. It combines anodic scanning voltammetry with the rotating-disk electrode and provides a method for measuring kinetic dissociation rates in situ, along with a method for distinguishing labile and non-labile complexes kinetically, consistent with the way they are defined. 

Two types of cell have been described. In Fig. 1 a cell with a rotating disk electrode is shown. Connections to a pH-stat and to the interface are indicated simultaneously with recording CMT measurements, the metal and reference electrode and a counter electrode (not shown in Fig. 1) can be connected to a potentiostat, so that electrochemical measurements can be recorded intermittently. The volume of solution in the cell is ca. 400 ml. What matters for safe and reliable conditions of measurement is that the disk electrode rotating at a speed of no less than 1000 rpm ensures efficient stirring, so that the effect of alkali formed at the corroding metal (or sometimes at the counter electrode located ca. 1 cm below and parallel to the metal electrode) is immediately sensed effectively by the glass electrode and also the effect of acid supplied from the autoburet is quickly detected. 

Data from Ref. 137, measured at 2 mM in CH3CN with 100 mM tetraethylammonium perchlorate, with a platinum or glassy carbon rotating disk electrode and a scan speed of 250 mV s. ... 

Are Rotating Disk with Ring Electrodes Still Useful in the Twenty-first Century When the rotating disk electrode was first used, it was the 1960s since that time, many new methods for measuring electrode reactions (above all, spectroscopic ones, e.g., those in Section 7.5.15), have been invented. Furthermore, microelectrodes have made it possible, in effect, to reduce 5 by as much as 1000 times compared with that in a still solution, so that one of the uses of the rotating disk... 

The measurement of a molecular diffusion coefficient D by electrochemical techniques is generally done with a rotating disk electrode in the limiting diffusion current condition and application of the Levich s equation [8]. 

The application of surface-enhanced Raman spectroscopy (SERS) for monitoring redox and other processes at metal-solution interfaces is illustrated by means of some recent results obtained in our laboratory. The detection of adsorbed species present at outer- as well as inner-sphere reaction sites is noted. The influence of surface interaction effects on the SER spectra of adsorbed redox couples is discussed with a view towards utilizing the frequency-potential dependence of oxidation-state sensitive vibrational modes as a criterion of reactant-surface electronic coupling effects. Illustrative data are presented for Ru(NH3)63+/2+ adsorbed electrostatically to chloride-coated silver, and Fe(CN)63 /" bound to gold electrodes the latter couple appears to be valence delocalized under some conditions. The use of coupled SERS-rotating disk voltammetry measurements to examine the kinetics and mechanisms of irreversible and multistep electrochemical reactions is also discussed. Examples given are the outer- and inner-sphere one-electron reductions of Co(III) and Cr(III) complexes at silver, and the oxidation of carbon monoxide and iodide at gold electrodes. 

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